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Bharadwaj S, Groza Y, Mierzwicka JM, Malý P. Current understanding on TREM-2 molecular biology and physiopathological functions. Int Immunopharmacol 2024; 134:112042. [PMID: 38703564 DOI: 10.1016/j.intimp.2024.112042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/05/2024] [Accepted: 04/05/2024] [Indexed: 05/06/2024]
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM-2), a glycosylated receptor belonging to the immunoglobin superfamily and especially expressed in the myeloid cell lineage, is frequently explained as a reminiscent receptor for both adaptive and innate immunity regulation. TREM-2 is also acknowledged to influence NK cell differentiation via the PI3K and PLCγ signaling pathways, as well as the partial activation or direct inhibition of T cells. Additionally, TREM-2 overexpression is substantially linked to cell-specific functions, such as enhanced phagocytosis, reduced toll-like receptor (TLR)-mediated inflammatory cytokine production, increased transcription of anti-inflammatory cytokines, and reshaped T cell function. Whereas TREM-2-deficient cells exhibit diminished phagocytic function and enhanced proinflammatory cytokines production, proceeding to inflammatory injuries and an immunosuppressive environment for disease progression. Despite the growing literature supporting TREM-2+ cells in various diseases, such as neurodegenerative disorders and cancer, substantial facets of TREM-2-mediated signaling remain inadequately understood relevant to pathophysiology conditions. In this direction, herein, we have summarized the current knowledge on TREM-2 biology and cell-specific TREM-2 expression, particularly in the modulation of pivotal TREM-2-dependent functions under physiopathological conditions. Furthermore, molecular regulation and generic biological relevance of TREM-2 are also discussed, which might provide an alternative approach for preventing or reducing TREM-2-associated deformities. At last, we discussed the TREM-2 function in supporting an immunosuppressive cancer environment and as a potential drug target for cancer immunotherapy. Hence, summarized knowledge of TREM-2 might provide a window to overcome challenges in clinically effective therapies for TREM-2-induced diseases in humans.
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Affiliation(s)
- Shiv Bharadwaj
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV Research Center, Průmyslová 595, 252 50 Vestec, Czech Republic.
| | - Yaroslava Groza
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV Research Center, Průmyslová 595, 252 50 Vestec, Czech Republic
| | - Joanna M Mierzwicka
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV Research Center, Průmyslová 595, 252 50 Vestec, Czech Republic
| | - Petr Malý
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV Research Center, Průmyslová 595, 252 50 Vestec, Czech Republic.
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2
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Hwang M, Bergmann CC. Neurotropic murine coronavirus mediated demyelination: Factors dampening pathogenesis. J Neuroimmunol 2024; 393:578382. [PMID: 38850674 DOI: 10.1016/j.jneuroim.2024.578382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 05/12/2024] [Accepted: 05/31/2024] [Indexed: 06/10/2024]
Abstract
Virus infections and autoimmune responses are implicated as primary triggers of demyelinating diseases. Specifically, the association of Epstein-Barr virus (EBV) infection with development of multiple sclerosis (MS) has re-ignited an interest in virus induced autoimmune responses to CNS antigens. Nevertheless, demyelination may also be caused by immune mediated bystander pathology in an attempt to control direct infection in the CNS. Tissue damage as a result of anti-viral responses or low level viral persistence may lead to immune activation manifesting in demyelinating lesions, axonal damage and clinical symptoms. This review focuses on the neurotropic mouse coronavirus induced demyelination model to highlight how immune responses activated during the acute phase pave the way to dampen pathology and promote repair. We specifically discuss the role of immune dampening factors programmed cell death ligand 1 (PD-L1) and interleukin (IL)-10, as well as microglia and triggering receptor expressed on myeloid cells 2 (Trem2), in limiting demyelination independent of viral persistence.
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Affiliation(s)
- Mihyun Hwang
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, USA; Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Cornelia C Bergmann
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, USA; Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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3
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Matos ADO, Dantas PHDS, Queiroz HAGDB, Silva-Sales M, Sales-Campos H. TREM-2: friend or foe in infectious diseases? Crit Rev Microbiol 2024; 50:1-19. [PMID: 36403150 DOI: 10.1080/1040841x.2022.2146481] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 11/07/2022] [Indexed: 11/21/2022]
Abstract
The triggering receptor expressed on myeloid cells-2 (TREM-2) is an immune receptor expressed on immune and non-immune cells, more frequently investigated in neurodegenerative disorders and considered a marker for microglia activation. In infectious diseases, the receptor was initially believed to be an anti-inflammatory molecule, opposing the inflammation triggered by TREM-1. Currently, TREM-2 is associated with different aspects in response to infectious stimuli, including the induction of bacterial phagocytosis and clearance, containment of exacerbated pro-inflammatory responses, induction of M2 differentiation and activation of Th1 lymphocytes, besides of neurological damage after viral infection. Here, we present and discuss results published in the last two decades regarding the expression, activation and functions of TREM-2 during the course of bacterial, viral, fungal and parasitic infections. A surprisingly plasticity was observed regarding the roles of the receptor in the aforementioned contexts, which largely varied according to the cell/organ and pathogen type, besides influencing disease outcome. Therefore, our review aimed to critically overview the role of TREM-2 in infectious diseases, highlighting its potential to be used as a clinical biomarker or therapeutic target.
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Affiliation(s)
| | | | | | - Marcelle Silva-Sales
- Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, Brazil
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Wu Z, Yang S, Fang X, Shu Q, Chen Q. Function and mechanism of TREM2 in bacterial infection. PLoS Pathog 2024; 20:e1011895. [PMID: 38236825 PMCID: PMC10796033 DOI: 10.1371/journal.ppat.1011895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2024] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2), which is a lipid sensing and phagocytosis receptor, plays a key role in immunity and inflammation in response to pathogens. Here, we review the function and signaling of TREM2 in microbial binding, engulfment and removal, and describe TREM2-mediated inhibition of inflammation by negatively regulating the Toll-like receptor (TLR) response. We further illustrate the role of TREM2 in restoring organ homeostasis in sepsis and soluble TREM2 (sTREM2) as a diagnostic marker for sepsis-associated encephalopathy (SAE). Finally, we discuss the prospect of TREM2 as an interesting therapeutic target for sepsis.
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Affiliation(s)
- Zehua Wu
- Department of the Clinical Research Center, Children’s Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
| | - Shiyue Yang
- Department of Anesthesiology, First Affiliated Hospital of Soochow University, Soochow, People’s Republic of China
| | - Xiangming Fang
- Department of Anesthesiology and Intensive Care, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
| | - Qiang Shu
- Department of the Clinical Research Center, Children’s Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
- Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, Hangzhou, People’s Republic of China
| | - Qixing Chen
- Department of the Clinical Research Center, Children’s Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
- Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, Hangzhou, People’s Republic of China
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5
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Hosseinzadeh S, Afshari S, Molaei S, Rezaei N, Dadkhah M. The role of genetics and gender specific differences in neurodegenerative disorders: Insights from molecular and immune landscape. J Neuroimmunol 2023; 384:578206. [PMID: 37813041 DOI: 10.1016/j.jneuroim.2023.578206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/09/2023] [Accepted: 09/23/2023] [Indexed: 10/11/2023]
Abstract
Neurodegenerative disorders (NDDs) are the most common neurological disorders with high prevalence and have significant socioeconomic implications. Understanding the underlying cellular and molecular mechanisms associated with the immune system can be effective in disease etiology, leading to more effective therapeutic approaches for both females and males. The central nervous system (CNS) actively participates in immune responses, both within and outside the CNS. Immune system activation is a common feature in NDDs. Gender-specific factors play a significant role in the prevalence, progression, and manifestation of NDDs. Neuroinflammation, in both inflammatory neurological and neurodegenerative conditions, is defined by the triggering of microglia and astrocyte cell activation. This results in the secretion of pro-inflammatory cytokines and chemokines. Numerous studies have documented the role of neuroinflammation in neurological diseases, highlighting the involvement of immune signaling pathways in disease development. Converging evidence support immune system involvement during neurodegeneration in NDDs. In this review, we summarize emerging evidence that reveals gender-dependent differences in immune responses related to NDDs. Also, we highlight sex differences in immune responses and discuss how these sex-specific influences can increase the risk of NDDs. Understanding the role of gender-specific factors can aid in developing targeted therapeutic strategies and improving patient outcomes. Ultimately, the better understanding of these mechanisms contributed to sex-dependent immune response in NDDs, can be critically usful in targeting of immune signaling cascades in such disorders. In this regard, sex-related immune responses in NDDs may be promising and effective targets in therapeutic strategies.
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Affiliation(s)
- Shahnaz Hosseinzadeh
- Department of Microbiology & Immunology, School of Medicine, Ardabil University of Medical Sciences, Iran; Cancer Immunology and Immunotherapy Research Center, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Salva Afshari
- Students Research Committee, Pharmacy School, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Soheila Molaei
- Zoonoses Research Center, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Nima Rezaei
- Research Center for Immunodeficiencies, Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran 1419733151, Iran; Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education Research Network (USERN), Tehran, Iran
| | - Masoomeh Dadkhah
- Pharmaceutical Sciences Research Center, Ardabil University of Medical Sciences, Ardabil, Iran.
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Thom RE, Williamson ED, Casulli J, Butcher WA, Burgess G, Laws TR, Huxley P, Ashfield R, Travis MA, D’Elia RV. Assessment of CD200R Activation in Combination with Doxycycline in a Model of Melioidosis. Microbiol Spectr 2023; 11:e0401622. [PMID: 37199641 PMCID: PMC10269878 DOI: 10.1128/spectrum.04016-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 04/17/2023] [Indexed: 05/19/2023] Open
Abstract
Antimicrobial resistance continues to be a global issue. Pathogens, such as Burkholderia pseudomallei, have evolved mechanisms to efflux certain antibiotics and manipulate the host response. New treatment strategies are therefore required, such as a layered defense approach. Here, we demonstrate, using biosafety level 2 (BSL-2) and BSL-3 in vivo murine models, that combining the antibiotic doxycycline with an immunomodulatory drug that targets the CD200 axis is superior to antibiotic treatment in combination with an isotype control. CD200-Fc treatment alone significantly reduces bacterial burden in lung tissue in both the BSL-2 and BSL-3 models. When CD200-Fc treatment is combined with doxycycline to treat the acute BSL-3 model of melioidosis, there is a 50% increase in survival compared with relevant controls. This benefit is not due to increasing the area under the concentration-time curve (AUC) of the antibiotic, suggesting the immunomodulatory nature of CD200-Fc treatment is playing an important role by potentially controlling the overactive immune response seen with many lethal bacterial infections. IMPORTANCE Traditional treatments for infectious disease have focused on the use of antimicrobial compounds (e.g. antibiotics) that target the infecting organism. However, timely diagnosis and administration of antibiotics remain crucial to ensure efficacy of these treatments especially for the highly virulent biothreat organisms. The need for early antibiotic treatment, combined with the increasing emergence of antibiotic resistant bacteria, means that new therapeutic strategies are required for organisms that cause rapid, acute infections. Here, we show that a layered defense approach, where an immunomodulatory compound is combined with an antibiotic, is better than an antibiotic combined with a relevant isotype control following infection with the biothreat agent Burkholderia pseudomallei. This approach has the potential to be truly broad spectrum and since the strategy includes manipulation of the host response it's application could be used in the treatment of a wide range of diseases.
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Affiliation(s)
- R. E. Thom
- CBR Division Defence Science and Technology Laboratory Porton Down, Salisbury, United Kingdom
| | - E. D. Williamson
- CBR Division Defence Science and Technology Laboratory Porton Down, Salisbury, United Kingdom
| | - J. Casulli
- Lydia Becker Institute for Immunology and Inflammation, Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, United Kingdom
| | - W. A. Butcher
- CBR Division Defence Science and Technology Laboratory Porton Down, Salisbury, United Kingdom
| | - G. Burgess
- CBR Division Defence Science and Technology Laboratory Porton Down, Salisbury, United Kingdom
| | - T. R. Laws
- CBR Division Defence Science and Technology Laboratory Porton Down, Salisbury, United Kingdom
| | - P. Huxley
- Ducentis BioTherapeutics Ltd., Oxford, Oxfordshire, United Kingdom
| | - R. Ashfield
- Ducentis BioTherapeutics Ltd., Oxford, Oxfordshire, United Kingdom
| | - M. A. Travis
- Lydia Becker Institute for Immunology and Inflammation, Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, United Kingdom
| | - R. V. D’Elia
- CBR Division Defence Science and Technology Laboratory Porton Down, Salisbury, United Kingdom
- Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
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7
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Hwang M, Savarin C, Kim J, Powers J, Towne N, Oh H, Bergmann CC. Trem2 deficiency impairs recovery and phagocytosis and dysregulates myeloid gene expression during virus-induced demyelination. J Neuroinflammation 2022; 19:267. [PMID: 36333761 PMCID: PMC9635103 DOI: 10.1186/s12974-022-02629-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022] Open
Abstract
Background Triggering receptor expressed on myeloid cells 2 (Trem2) plays a protective role in neurodegenerative diseases. By contrast, Trem2 functions can exacerbate tissue damage during respiratory viral or liver infections. We, therefore, investigated the role of Trem2 in a viral encephalomyelitis model associated with prominent Th1 mediated antiviral immunity leading to demyelination. Methods Wild-type (WT) and Trem2 deficient (Trem2−/−) mice were infected with a sublethal glia tropic murine coronavirus (MHV–JHM) intracranially. Disease progression and survival were monitored daily. Leukocyte accumulation and pathological features including demyelination and axonal damage in spinal cords (SC) were determined by flow cytometry and tissue section immunofluorescence analysis. Expression of select inflammatory cytokines and chemokines was measured by RT-PCR and global myeloid cell gene expression in SC-derived microglia and infiltrated bone-marrow-derived macrophages (BMDM) were determined using the Nanostring nCounter platform. Results BMDM recruited to SCs in response to infection highly upregulated Trem2 mRNA compared to microglia coincident with viral control. Trem2 deficiency did not alter disease onset or severity, but impaired clinical recovery after onset of demyelination. Disease progression in Trem2−/− mice could not be attributed to altered virus control or an elevated proinflammatory response. A prominent difference was increased degenerated myelin not associated with the myeloid cell markers IBA1 and/or CD68. Gene expression profiles of SC-derived microglia and BMDM further revealed that Trem2 deficiency resulted in impaired upregulation of phagocytosis associated genes Lpl and Cd36 in microglia, but a more complex pattern in BMDM. Conclusions Trem2 deficiency during viral-induced demyelination dysregulates expression of other select genes regulating phagocytic pathways and lipid metabolism, with distinct effects on microglia and BMDM. The ultimate failure to remove damaged myelin is reminiscent of toxin or autoimmune cell-induced demyelination models and supports that Trem2 function is regulated by sensing tissue damage including a dysregulated lipid environment in very distinct inflammatory environments. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-022-02629-1.
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Wang Y, Cao C, Zhu Y, Fan H, Liu Q, Liu Y, Chen K, Wu Y, Liang S, Li M, Li L, Liu X, Zhang Y, Wu C, Lu G, Wu M. TREM2/β-catenin attenuates NLRP3 inflammasome-mediated macrophage pyroptosis to promote bacterial clearance of pyogenic bacteria. Cell Death Dis 2022; 13:771. [PMID: 36068223 PMCID: PMC9448748 DOI: 10.1038/s41419-022-05193-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/07/2022] [Accepted: 08/15/2022] [Indexed: 01/21/2023]
Abstract
Triggering receptors expressed on myeloid cells 2 (TREM2) is considered a protective factor to protect host from bacterial infection, while how it elicits this role is unclear. In the present study, we demonstrate that deficiency of triggering receptors expressed on myeloid cells 2 (TREM2) significantly enhanced macrophage pyroptosis induced by four common pyogenic bacteria including Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae, and Escherichia coli. TREM2 deficiency also decreased bacterial killing ratio of macrophage, while Caspase-1 or GSDMD inhibition promoted macrophage-mediated clearance to these bacteria. Further study demonstrated that the effect of TREM2 on macrophage pyroptosis and bacterial eradication mainly dependents on the activated status of NLRP3 inflammasome. Moreover, as the key downstream of TREM2, β-catenin phosphorylated at Ser675 by TREM2 signal and accumulated in nucleus and cytoplasm. β-catenin mediated the effect of TREM2 on NLRP3 inflammasome and macrophage pyroptosis by reducing NLRP3 expression, and inhibiting inflammasome complex assembly by interacting with ASC. Collectively, TREM2/β-catenin inhibits NLRP3 inflammasome to regulate macrophage pyroptosis, and enhances macrophage-mediated pyogenic bacterial clearance.
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Affiliation(s)
- Yi Wang
- grid.411866.c0000 0000 8848 7685Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, 510120 China
| | - Can Cao
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XKey Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080 China
| | - Yanting Zhu
- grid.411866.c0000 0000 8848 7685Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, 510120 China
| | - Huifeng Fan
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Qiaojuan Liu
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XKey Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080 China
| | - Yiting Liu
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XKey Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080 China
| | - Kang Chen
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XKey Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080 China
| | - Yongjian Wu
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XKey Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080 China
| | - Siping Liang
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XKey Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080 China
| | - Meiyu Li
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XKey Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080 China
| | - Lexi Li
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Xi Liu
- grid.12981.330000 0001 2360 039XKey Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080 China
| | - Yuanqing Zhang
- grid.12981.330000 0001 2360 039XSchool of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006 China
| | - Chenglin Wu
- grid.12981.330000 0001 2360 039XOrgan Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Gen Lu
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Minhao Wu
- grid.12981.330000 0001 2360 039XProgram of Infection and Immunity, Affiliated Guangzhou Women and Children’s Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XKey Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, 510080 China ,grid.12981.330000 0001 2360 039XGuangdong Engineering & Technology Research Center for Disease-Model Animals, Sun Yat-sen University, Guangzhou, 510006 China
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Huang L, Tang H, Hu J. METTL3 Attenuates Inflammation in Fusarium solani-Induced Keratitis via the PI3K/AKT Signaling Pathway. Invest Ophthalmol Vis Sci 2022; 63:20. [PMID: 36169946 PMCID: PMC9526359 DOI: 10.1167/iovs.63.10.20] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 09/12/2022] [Indexed: 12/03/2022] Open
Abstract
Purpose Our previous investigations revealed a significant role of methyltransferase-like 3 (METTL3)-mediated N6-methyladenosine (m6A) modification in the development of corneal inflammation in Fusarium infection, but the exact mechanism is unknown. Therefore, this research aimed to explore how METTL3 affects the inflammatory process of fungal keratitis (FK) in mice. Methods We established in vitro and in vivo models by inoculating mice and primary corneal stromal cells with F. solani. METTL3 expression was confirmed by real-time quantitative polymerase chain reaction, immunofluorescence, and western blotting. After that, siRNAMETTL3 and AAV-sh-METTL3 were transfected into cells and mice to explore the role of METTL3 in the PI3K/AKT signaling pathway and inflammation. PI3K, p-PI3K, AKT, and p-AKT expression was analyzed by western blotting. Viability of corneal stromal cells was measured using a Cell Counting Kit-8 (CCK-8). Additionally, we detected interleukin (IL)-6, IL-1β, and tumor necrosis factor alpha (TNF-α) levels in corneal tissues and analyzed the role of METTL3 in inflammation in FK using slit-lamp biomicroscopy and hematoxylin and eosin staining. Results Here, our results show that METTL3 increased in mouse FK, and the expression of p-PI3K and p-AKT decreased when METTL3 was downregulated. We also found that knockdown of METTL3 expression attenuated the inflammatory response and decreased TNF-α, IL-1β, and IL-6 expression in corneal-infected mice. Furthermore, inhibition of the PI3K/AKT pathway attenuated the inflammatory response of FK, decreased the expression of the above inflammatory factors, and enhanced the viability of corneal stromal cells. Conclusions Based on the study results, METTL3 downregulation attenuates Fusarium-induced corneal inflammation via the PI3K/AKT signaling pathway.
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Affiliation(s)
- Liwei Huang
- Department of Ophthalmology, Fujian Medical University Union Hospital, Fu Zhou, China
| | - Hanfeng Tang
- Department of Ophthalmology, Fujian Medical University Union Hospital, Fu Zhou, China
| | - Jianzhang Hu
- Department of Ophthalmology, Fujian Medical University Union Hospital, Fu Zhou, China
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10
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Tang H, Yang D, Zhu L, Shi F, Ye G, Guo H, Deng H, Zhao L, Xu Z, Li Y. Paeonol Interferes With Quorum-Sensing in Pseudomonas aeruginosa and Modulates Inflammatory Responses In Vitro and In Vivo. Front Immunol 2022; 13:896874. [PMID: 35686124 PMCID: PMC9170885 DOI: 10.3389/fimmu.2022.896874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 04/19/2022] [Indexed: 11/19/2022] Open
Abstract
Developing quorum-sensing (QS) based anti-infection drugs is one of the most powerful strategies to combat multidrug-resistant bacteria. Paeonol has been proven to attenuate the QS-controlled virulence factors of P. aeruginosa by down-regulating the transcription of QS signal molecules. This research aimed to assess the anti-virulence activity and mechanism of paeonol against P. aeruginosa infection in vitro and in vivo. In this study, paeonol was found to reduce the adhesion and invasion of P.aeruginosa to macrophages and resist the cytotoxicity induced by P.aeruginosa. Paeonol reduced the expression of virulence factors of P.aeruginosa by inhibiting QS, thereby reducing the LDH release and damage of P.aeruginosa-infected macrophages. Paeonol can inhibit bacterial virulence and enhance the ability of macrophages to clear P.aeruginosa. In addition, paeonol exerts anti-inflammatory activity by reducing the expression of inflammatory cytokines and increasing the production of anti-inflammatory cytokines. Paeonol treatment significantly inhibited the activation of TLR4/MyD88/NF-κB signaling pathway and decreased the inflammation response of P. aeruginosa-infected macrophages. Paeonol also significantly reduced the ability of P.aeruginosa to infect mice and reduced the inflammatory response. These data suggest that paeonol can inhibit the virulence of P.aeruginosa and decrease the inflammation response in P.aeruginosa-infected macrophages and mice, which can decrease the damage induced by P.aeruginosa infection and enhance the ability of macrophages to clear bacteria. This study supports the further development of new potential anti-infective drugs based on inhibition of QS and virulence factors.
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Affiliation(s)
- Huaqiao Tang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Dan Yang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhu
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Fei Shi
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Gang Ye
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Hongrui Guo
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Huidan Deng
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhao
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Zhiwen Xu
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yinglun Li
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
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11
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Lu L, Liu X, Fu J, Liang J, Hou Y, Dou H. sTREM-1 promotes the phagocytic function of microglia to induce hippocampus damage via the PI3K-AKT signaling pathway. Sci Rep 2022; 12:7047. [PMID: 35487953 PMCID: PMC9054830 DOI: 10.1038/s41598-022-10973-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 04/15/2022] [Indexed: 12/18/2022] Open
Abstract
Soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) is a soluble form of TREM-1 released during inflammation. Elevated sTREM-1 levels have been found in neuropsychiatric systemic lupus erythematosus (NPSLE) patients; yet, the exact mechanisms remain unclear. This study investigated the role of sTREM-1 in brain damage and its underlying mechanism. The sTREM-1 recombinant protein (2.5 μg/3 μL) was injected into the lateral ventricle of C57BL/6 female mice. After intracerebroventricular (ICV) injection, the damage in hippocampal neurons increased, and the loss of neuronal synapses and activation of microglia increased compared to the control mice (treated with saline). In vitro. after sTREM-1 stimulation, the apoptosis of BV2 cells decreased, the polarization of BV2 cells shifted to the M1 phenotype, the phagocytic function of BV2 cells significantly improved, while the PI3K-AKT signal pathway was activated in vivo and in vitro. PI3K-AKT pathway inhibitor LY294002 reversed the excessive activation and phagocytosis of microglia caused by sTREM-1 in vivo and in vitro, which in turn improved the hippocampus damage. These results indicated that sTREM-1 activated the microglial by the PI3K-AKT signal pathway, and promoted its excessive phagocytosis of the neuronal synapse, thus inducing hippocampal damage. sTREM-1 might be a potential target for inducing brain lesions.
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Affiliation(s)
- Li Lu
- The State Key Laboratory of Pharmaceutical Biotechnology, Division of Immunology, Medical School, Nanjing University, Nanjing, 210093, People's Republic of China.,Jiangsu Key Laboratory of Molecular Medicine, Nanjing, 210093, People's Republic of China
| | - Xuan Liu
- The State Key Laboratory of Pharmaceutical Biotechnology, Division of Immunology, Medical School, Nanjing University, Nanjing, 210093, People's Republic of China.,Jiangsu Key Laboratory of Molecular Medicine, Nanjing, 210093, People's Republic of China
| | - Juanhua Fu
- The State Key Laboratory of Pharmaceutical Biotechnology, Division of Immunology, Medical School, Nanjing University, Nanjing, 210093, People's Republic of China.,Jiangsu Key Laboratory of Molecular Medicine, Nanjing, 210093, People's Republic of China
| | - Jun Liang
- Department of Rheumatology and Immunology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, People's Republic of China.
| | - Yayi Hou
- The State Key Laboratory of Pharmaceutical Biotechnology, Division of Immunology, Medical School, Nanjing University, Nanjing, 210093, People's Republic of China. .,Jiangsu Key Laboratory of Molecular Medicine, Nanjing, 210093, People's Republic of China.
| | - Huan Dou
- The State Key Laboratory of Pharmaceutical Biotechnology, Division of Immunology, Medical School, Nanjing University, Nanjing, 210093, People's Republic of China. .,Jiangsu Key Laboratory of Molecular Medicine, Nanjing, 210093, People's Republic of China.
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12
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Okuzono Y, Sakuma H, Miyakawa S, Ifuku M, Lee J, Das D, Banerjee A, Zhao Y, Yamamoto K, Ando T, Sato S. Reduced TREM2 activation in microglia of patients with Alzheimer's disease. FEBS Open Bio 2021; 11:3063-3080. [PMID: 34523252 PMCID: PMC8564098 DOI: 10.1002/2211-5463.13300] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 08/27/2021] [Accepted: 09/13/2021] [Indexed: 12/13/2022] Open
Abstract
Loss-of-function variants of triggering receptor expressed on myeloid cells 2 (TREM2) increase the risk of developing Alzheimer's disease (AD). The mechanism through which TREM2 contributes to the disease (TREM2 activation vs inactivation) is largely unknown. Here, we analyzed changes in a gene set downstream of TREM2 to determine whether TREM2 signaling is modified by AD progression. We generated an anti-human TREM2 agonistic antibody and defined TREM2 activation in terms of the downstream expression changes induced by this antibody in microglia developed from human induced pluripotent stem cells (iPSC). Differentially expressed genes (DEGs) following TREM2 activation were compared with the gene set extracted from microglial single nuclear RNA sequencing data of patients with AD, using gene set enrichment analysis. We isolated an anti-TREM2-specific agonistic antibody, Hyb87, from anti-human TREM2 antibodies generated using binding and agonism assays, which helped us identify 300 upregulated and 251 downregulated DEGs. Pathway enrichment analysis suggested that TREM2 activation may be associated with Th2-related pathways. TREM2 activation was lower in AD microglia than in microglia from healthy subjects or patients with mild cognitive impairment. TREM2 activation also showed a significant negative correlation with disease progression. Pathway enrichment analysis of DEGs controlled by TREM2 activity indicated that TREM2 activation in AD may lead to anti-apoptotic signaling, immune response, and cytoskeletal changes in the microglia. We showed that TREM2 activation decreases with AD progression, in support of a protective role of TREM2 activation in AD. In addition, the agonistic anti-TREM2 antibody can be used to identify TREM2 activation state in AD microglia.
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Affiliation(s)
- Yuumi Okuzono
- Immune Cell Engineered TherapeuticsResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Hiroyuki Sakuma
- Neuroscience Drug Discovery UnitResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Shuuichi Miyakawa
- Immune Cell Engineered TherapeuticsResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Masataka Ifuku
- Immune Cell Engineered TherapeuticsResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Jonghun Lee
- Computational BiologyResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Debashree Das
- Early Target DiscoveryResearch, Takeda California, Inc.San DiegoCAUSA
| | - Antara Banerjee
- GI ImmunologyResearch, Takeda California, Inc.San DiegoCAUSA
| | - Yang Zhao
- Computational BiologyResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Koji Yamamoto
- Computational BiologyResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Tatsuya Ando
- Computational BiologyResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
| | - Shuji Sato
- Neuroscience Drug Discovery UnitResearch, Takeda Pharmaceutical Company LimitedFujisawaJapan
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13
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Qiu H, Shao Z, Wen X, Jiang J, Ma Q, Wang Y, Huang L, Ding X, Zhang L. TREM2: Keeping Pace With Immune Checkpoint Inhibitors in Cancer Immunotherapy. Front Immunol 2021; 12:716710. [PMID: 34539652 PMCID: PMC8446424 DOI: 10.3389/fimmu.2021.716710] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 08/18/2021] [Indexed: 01/21/2023] Open
Abstract
To date, immune checkpoint inhibitors have been successively approved and widely used in clinical cancer treatments, however, the overall response rates are very low and almost all cancer patients eventually progressed to drug resistance, this is mainly due to the intricate tumor microenvironment and immune escape mechanisms of cancer cells. One of the main key mechanisms leading to the evasion of immune attack is the presence of the immunosuppressive microenvironment within tumors. Recently, several studies illustrated that triggering receptor expressed on myeloid cells-2 (TREM2), a transmembrane receptor of the immunoglobulin superfamily, was a crucial pathology-induced immune signaling hub, and it played a vital negative role in antitumor immunity, such as inhibiting the proliferation of T cells. Here, we reviewed the recent advances in the study of TREM2, especially focused on its regulation of tumor-related immune signaling pathways and its role as a novel target in cancer immunotherapy.
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Affiliation(s)
- Hui Qiu
- Cancer Institute, Xuzhou Medical University, Xuzhou, China.,Department of Radiation Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Zhiying Shao
- Cancer Institute, Xuzhou Medical University, Xuzhou, China
| | - Xin Wen
- Cancer Institute, Xuzhou Medical University, Xuzhou, China.,Department of Radiation Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Jinghua Jiang
- Department of Radiation Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Qinggong Ma
- Department of Radiation Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Yan Wang
- Department of Radiation Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Long Huang
- Department of Radiation Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Xin Ding
- Cancer Institute, Xuzhou Medical University, Xuzhou, China.,Department of Radiation Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Longzhen Zhang
- Cancer Institute, Xuzhou Medical University, Xuzhou, China.,Department of Radiation Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
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14
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Regulation of TREM1-Mediated Inflammation in Hepatocellular Carcinoma Cells. REPORTS 2021. [DOI: 10.3390/reports4020017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Hepatocellular carcinoma (HCC), accounting for more than 90% of cases of primary liver cancer, is the third most common cause of cancer-related death worldwide. Chronic inflammation precedes the development of cirrhosis and HCC. TREM (triggering receptor expressed on myeloid cell)-1 is an inflammatory marker and amplifier of inflammation that signals through PI3K and ERK1/2 to activate transcription factors, resulting in increased secretion of pro-inflammatory cytokines, causing chronic inflammation and predisposing the liver to carcinogenesis. Thus, targeting TREM-1 in HCC might be a potential therapeutic target. A low level of vitamin D has been associated with chronic inflammation and poor prognosis in HCC. Thus, we evaluated the effect of vitamin D on TREM-1 expression in the HCC cell line. Additionally, the effects of high mobility group box-1, lipopolysaccharide, and transcription factor PU.1 on the expression of TREM-1 in normal liver cells and HCC cells have been investigated in the presence and absence of vitamin D. The results showed increased expression of TREM-1 in HCC cells and with IL-6, TNF-α, LPS, and rHMGB-1 and decreased expression with calcitriol. Calcitriol also attenuated the effect of IL-6, TNF-α, LPS, and rHMGB-1 on TREM-1. Calcitriol treatment attenuated the proliferation, migration, and invasion of HCC cells. These results (in vitro) provide molecular and biochemical evidence that calcitriol significantly attenuates the expression of mediators of inflammation, and thus might be used therapeutically together with conventional treatment to delay the progression of HCC. Additionally, the negative regulation of TREM-1 by PU.1 suggests PU.1 as a potential therapeutic target.
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15
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Shafi S, Singh A, Ibrahim AM, Alhajri N, Abu Izneid T, Pottoo FH. Role of triggering receptor expressed on myeloid cells 2 (TREM2) in neurodegenerative dementias. Eur J Neurosci 2021; 53:3294-3310. [PMID: 33786894 DOI: 10.1111/ejn.15215] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 03/22/2021] [Indexed: 01/04/2023]
Abstract
Neurodegeneration is a debilitating condition that causes nerve cell degeneration or death. Neurodegenerative diseases (NDDs) such as Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal dementia (FTD), and Lewy body dementia (LBD) are posing a larger population burden of dementia worldwide. Neurodegenerative dementia is one of the main challenges in public health with its main characteristics being permanent loss of memory, impairment in cognition, and impaired daily functions. The published literature about genetic studies of these disorders suggests genetic underpinning in the pathogenesis of neurodegenerative dementia. In the process of underlining the pathogenesis of NDD, growing evidence has related genetic variations in the triggering receptor expressed on myeloid cells 2 (TREM2). This review paper aims to provide a detailed information regarding the association of TREM2 and NDDs leading to dementia. A central consideration is AD that accounts for almost 50%-70% of all late-life dementias alone or in combination with other neurological disorders. Other prevalent neurodegenerative conditions that lead to dementia are also discussed. Such studies are important as they can give a comprehensive knowledge of TREM2's role in various NDDs, in order to maximize the potential for developing new therapeutic approaches.
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Affiliation(s)
- Sadat Shafi
- Pharmaceutical Medicine, Department of Pharmacology, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, India
| | - Archu Singh
- Department of Pharmaceutics, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, India
| | - Abdallah Mohammad Ibrahim
- Fundamentals of Nursing Department, College of Nursing, Imam Abdul Rahman Bin Faisal University, Dammam, Saudi Arabia
| | - Noora Alhajri
- Department of Epidemiology and Population Health, College of Medicine and Health Science, Khalifa University, Abu Dhabi, UAE
| | | | - Faheem Hyder Pottoo
- Department of Pharmacology, College of Clinical Pharmacy, Imam Abdulrahman Bin Faisal University, Damman, Saudi Arabia
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16
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Hu J, Lin Y. Fusarium infection alters the m 6A-modified transcript landscape in the cornea. Exp Eye Res 2020; 200:108216. [PMID: 32890482 DOI: 10.1016/j.exer.2020.108216] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 08/30/2020] [Accepted: 09/01/2020] [Indexed: 12/28/2022]
Abstract
N6-methyladenosine (m6A) is the most common post-transcriptional modification of RNA in eukaryotes that regulates the post-transcriptional expression level of genes without changing the base sequence. The role of m6A in fungal keratitis has not yet been elucidated. Here, we aimed to identify m6A modification changes and their potential roles in fungal keratitis. The murine model of fungal keratitis was established by inoculating mice with Fusarium solani (F. solani). The overall m6A level was detected via an m6A RNA methylation assay kit. The expression levels of key m6A modification-related genes were estimated by quantitative real-time polymerase chain reaction (PCR). The expression and localization of METTL (methyltransferase like)3, the key component of the m6A methyltransferase complex, was determined by immunostaining and Western blotting (WB). Immunoprecipitation methylation microarray was used to describe the changes in m6A modification in F. solani-infected corneal tissue. The overall m6A level in corneal tissue on the 5th day in the F. solani-treated group was upregulated compared with that in the control group. The demethylase levels were unaltered, but the level of the methylase METTL3 was increased significantly after fungal infection. Additionally, differences were found in m6A modifications in 1137 mRNAs, of which 780 were hypermethylated and 357 were hypomethylated. To the best of our knowledge, the present work is the first investigation on the m6A modification profiles in experimental fungal keratitis, and it may provide a potential therapeutic target.
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Affiliation(s)
- Jianzhang Hu
- Department of Ophthalmology, Fujian Medical University Union Hospital, Fu Zhou, China.
| | - Yi Lin
- Department of Ophthalmology, Fujian Medical University Union Hospital, Fu Zhou, China
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17
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Microglia Implicated in Tauopathy in the Striatum of Neurodegenerative Disease Patients from Genotype to Phenotype. Int J Mol Sci 2020; 21:ijms21176047. [PMID: 32842621 PMCID: PMC7503242 DOI: 10.3390/ijms21176047] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 08/19/2020] [Accepted: 08/20/2020] [Indexed: 12/12/2022] Open
Abstract
We found interactions between dopamine and oxidative damage in the striatum involved in advanced neurodegeneration, which probably change the microglial phenotype. We observed possible microglia dystrophy in the striatum of neurodegenerative brains. To investigate the interactions between oxidative damage and microglial phenotype, we quantified myeloperoxidase (MPO), poly (ADP-Ribose) (PAR), and triggering receptors expressed on myeloid cell 2 (TREM2) using enzyme-linked immunosorbent assay (ELISA). To test the correlations of microglia dystrophy and tauopathy, we quantified translocator protein (TSPO) and tau fibrils using autoradiography. We chose the caudate and putamen of Lewy body diseases (LBDs) (Parkinson’s disease, Parkinson’s disease dementia, and Dementia with Lewy body), Alzheimer’s disease (AD), and control brains and genotyped for TSPO, TREM2, and bridging integrator 1 (BIN1) genes using single nucleotide polymorphisms (SNP) assays. TREM2 gene variants were absent across all samples. However, associations between TSPO and BIN1 gene polymorphisms and TSPO, MPO, TREM2, and PAR level variations were found. PAR levels reduced significantly in the caudate of LBDs. TSPO density and tau fibrils decreased remarkably in the striatum of LBDs but increased in AD. Oxidative damage, induced by misfolded tau proteins and dopamine metabolism, causes microglia dystrophy or senescence during the late stage of LBDs. Consequently, microglia dysfunction conversely reduces tau propagation. The G allele of the BIN1 gene is a potential risk factor for tauopathy.
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18
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Zhu S, Chen Y, Lao J, Wu C, Zhan X, Wu Y, Shang Y, Zou Z, Zhou J, Ji X, Huang X, Shi X, Wu M. Signaling Lymphocytic Activation Molecule Family-7 Alleviates Corneal Inflammation by Promoting M2 Polarization. J Infect Dis 2020; 223:854-865. [PMID: 32702113 DOI: 10.1093/infdis/jiaa445] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/11/2020] [Accepted: 07/17/2020] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Signaling lymphocytic activation molecule family-7 (SLAMF7) functions as an immune checkpoint molecule on macrophages in antitumor immunity. However, its role in bacterial infection remains largely unknown. METHODS Bone marrow-derived macrophages (BMDMs) isolated from wild-type (WT) or SLAMF7 knockout (KO) mice were infected with bacteria or treated with lipopolysaccharide/interferon-γ to investigate the expression and function of SLAMF7 in macrophage polarization. A Pseudomonas aeruginosa keratitis murine model was established to explore the effect of SLAMF7 on P. aeruginosa keratitis using WT vs SLAMF7 KO mice, or recombinant SLAMF7 vs phosphate-buffered saline-treated mice, respectively. RESULTS SLAMF7 expression was enhanced on M1-polarized or bacterial-infected macrophages, and infiltrating macrophages in P. aeruginosa-infected mouse corneas. SLAMF7 promoted M2 polarization by inducing STAT6 activation. In vivo data showed that SLAMF7 KO aggravated, while treatment with recombinant SLAMF7 alleviated, corneal inflammation and disease severity. In addition, blockage of M2 polarization by Arg-1 inhibitor abrogated the effect of recombinant SLAMF7 in disease progression. CONCLUSIONS SLAMF7 expression in macrophages was induced upon M1 polarization or bacterial infection and alleviated corneal inflammation and disease progression of P. aeruginosa keratitis by promoting M2 polarization. These findings may provide a potential strategy for the treatment of P. aeruginosa keratitis.
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Affiliation(s)
- Siying Zhu
- Program of Infection and Immunology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Yu Chen
- Program of Infection and Immunology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Juanfeng Lao
- Program of Infection and Immunology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Chenglin Wu
- Organ Transplantation Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Xiaoxia Zhan
- Department of Laboratory Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Yongjian Wu
- Program of Infection and Immunology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Yuqi Shang
- Department of Infectious Diseases, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, China
| | - Zhengyu Zou
- Program of Infection and Immunology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Jinyu Zhou
- Program of Infection and Immunology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Xiang Ji
- Program of Infection and Immunology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Xi Huang
- Department of Infectious Diseases, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, China
| | - Xiaomin Shi
- Organ Transplantation Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Minhao Wu
- Program of Infection and Immunology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China.,Guangdong Engineering and Technology Research Center for Disease-Model Animals, Sun Yat-sen University, Guangzhou, China
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19
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Chen S, Peng J, Sherchan P, Ma Y, Xiang S, Yan F, Zhao H, Jiang Y, Wang N, Zhang JH, Zhang H. TREM2 activation attenuates neuroinflammation and neuronal apoptosis via PI3K/Akt pathway after intracerebral hemorrhage in mice. J Neuroinflammation 2020; 17:168. [PMID: 32466767 PMCID: PMC7257134 DOI: 10.1186/s12974-020-01853-x] [Citation(s) in RCA: 155] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 05/21/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Neuroinflammation is an important host defense response to secondary brain injury after intracerebral hemorrhage (ICH). Triggering receptor expressed on myeloid cells 2 (TREM2) confers strong neuroprotective effects by attenuating neuroinflammation in experimental ischemic stroke. Recent studies suggest that apolipoprotein E (apoE) is a novel, high-affinity ligand of TREM2. This study aimed to investigate the effects of TREM2 activation on neuroinflammation and neuronal apoptosis in a mouse model of ICH. METHODS Adult male CD1 mice (n = 216) were subjected to intrastriatal injection of bacterial collagenase. The TREM2 ligand, apoE-mimetic peptide COG1410 was administered intranasally at 1 h after ICH induction. To elucidate the underlying mechanism, TREM2 small interfering RNA (siRNA) and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 were administered intracerebroventricularly prior to COG1410 treatment. Neurobehavioral tests, brain water content, immunofluorescence, western blotting, and Fluoro-Jade C- and terminal deoxynucleotidyl transferase dUTP nick end labeling staining were performed. RESULTS Endogenous TREM2 expression was increased and peaked at 24 h after ICH. TREM2 was expressed on microglia, astrocytes, and neurons. COG1410 improved both short-term and long-term neurological functions, reduced brain edema, inhibited microglia/macrophage activation and neutrophil infiltration, and suppressed neuronal apoptotic cell death in perihematomal areas after ICH. Knockdown of endogenous TREM2 by TREM2 siRNA aggravated neurological deficits and decreased the expression of TREM2 in naïve and ICH mice. COG1410 was associated with upregulation of TREM2, PI3K, phosphorylated-Akt, and Bcl-2 and downregulation of TNF-α, IL-1β, and Bax after ICH. The neuroprotective effects of COG1410 were abolished by both TREM2 siRNA and PI3K inhibitor LY294002. CONCLUSIONS Our finding demonstrated that TREM2 activation improved neurological functions and attenuated neuroinflammation and neuronal apoptosis after ICH, which was, at least in part, mediated by activation of PI3K/Akt signaling pathway. Therefore, activation of TREM2 may be a potential therapeutic strategy for the management of ICH patients.
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Affiliation(s)
- Shengpan Chen
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
- Department of Physiology and Pharmacology, Department of Neurosurgery and Anesthesiology, School of Medicine, Loma Linda University, Risley Hall, Room 219, 11041 Campus Street, Loma Linda, CA, 92354, USA
| | - Jianhua Peng
- Department of Physiology and Pharmacology, Department of Neurosurgery and Anesthesiology, School of Medicine, Loma Linda University, Risley Hall, Room 219, 11041 Campus Street, Loma Linda, CA, 92354, USA
- Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, China
| | - Prativa Sherchan
- Department of Physiology and Pharmacology, Department of Neurosurgery and Anesthesiology, School of Medicine, Loma Linda University, Risley Hall, Room 219, 11041 Campus Street, Loma Linda, CA, 92354, USA
| | - Yongjie Ma
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - Sishi Xiang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - Feng Yan
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - Hao Zhao
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - Yong Jiang
- Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, China
- Laboratory of Neurological Diseases and Brain Functions, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Ning Wang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China
| | - John H Zhang
- Department of Physiology and Pharmacology, Department of Neurosurgery and Anesthesiology, School of Medicine, Loma Linda University, Risley Hall, Room 219, 11041 Campus Street, Loma Linda, CA, 92354, USA.
- Department of Neurosurgery, Loma Linda University Medical Center, Loma Linda, CA, 92354, USA.
| | - Hongqi Zhang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, China International Neuroscience Institute (China-INI), No. 45 Changchun Street, Xicheng District, Beijing, 10053, China.
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20
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Subbannayya Y, Pinto SM, Mohanty V, Dagamajalu S, Prasad TSK, Murthy KR. What Makes Cornea Immunologically Unique and Privileged? Mechanistic Clues from a High-Resolution Proteomic Landscape of the Human Cornea. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2020; 24:129-139. [PMID: 32125911 DOI: 10.1089/omi.2019.0190] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Success rates of corneal transplantation are particularly high owing to its unique, innate immune privilege derived from a phenomenon known as Anterior Chamber-Associated Immune Deviation (ACAID). Of note, cornea is a transparent, avascular structure that acts as a barrier along with sclera to protect the eye and contributes to optical power. Molecular and systems biology mechanisms underlying ACAID and the immunologically unique and privileged status of cornea are not well known. We report here a global unbiased proteomic profiling of the human cornea and the identification of 4824 proteins, the largest catalog of human corneal proteins identified to date. Moreover, signaling pathway analysis revealed enrichment of spliceosome, phagosome, lysosome, and focal adhesion pathways, thereby demonstrating the protective functions of corneal proteins. We observed an enrichment of neutrophil-mediated immune response processes in the cornea as well as proteins belonging to the complement and ER-Phagosome pathways that are suggestive of active immune and inflammatory surveillance response. This study provides a key expression map of the corneal proteome repertoire that should enable future translational medicine studies on the pathological conditions of the cornea and the mechanisms by which cornea immunology are governed. Molecular mechanisms of corneal immune privilege have broad relevance to understand and anticipate graft rejection in the field of organ transplantation.
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Affiliation(s)
- Yashwanth Subbannayya
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
| | - Sneha M Pinto
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
| | - Varshasnata Mohanty
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
| | - Shobha Dagamajalu
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
| | | | - Krishna R Murthy
- Vittala International Institute of Ophthalmology, Bangalore, India.,Prabha Eye Clinic and Research Centre, Bangalore, India.,Institute of Bioinformatics, International Technology Park, Bangalore, India.,Manipal Academy of Higher Education, Manipal, India
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21
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He GL, Luo Z, Shen TT, Wang ZZ, Li P, Luo X, Yang J, Tan YL, Wang Y, Gao P, Yang XS. TREM2 Regulates Heat Acclimation-Induced Microglial M2 Polarization Involving the PI3K-Akt Pathway Following EMF Exposure. Front Cell Neurosci 2020; 13:591. [PMID: 32009907 PMCID: PMC6974802 DOI: 10.3389/fncel.2019.00591] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 12/30/2019] [Indexed: 12/15/2022] Open
Abstract
The function of triggering receptor expressed on myeloid cells-2 (TREM2) has been described within microglia with a beneficial activated phenotype. However, the role of TREM2 underlying microglial phenotypic alterations in the cross-tolerance protection of heat acclimation (HA) against the inflammatory stimuli electromagnetic field (EMF) exposure is less well known. Here, we investigated the TREM2-related signaling mechanism induced by HA in EMF-stimulated N9 microglial cells (N9 cells). We found that EMF exposure significantly increased the production of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α, IL-1β, and IL-6), and the expression of M1 markers (CD11b and CD86); meanwhile, decreased the levels of anti-inflammatory cytokines (IL-4 and IL-10) and the expression of M2 markers (CD206 and Arg1) in N9 cells. Clearly, HA treatment decreased the secretion of TNF-α, IL-1β and IL-6 and the expression of CD11b and CD86, and enhanced the production of IL-4 and IL-10 and the expression of CD206 and Arg1. Moreover, TREM2 esiRNA and selective inhibitor of PI3K clearly decreased anti-inflammatory cytokines production, M2 markers expression, and phosphorylation of PI3K and Akt following HA plus EMF stimulation. These results indicate that TREM2 and PI3K-Akt pathway are involved in the cross-tolerance protective effect of HA in microglial polarization towards the EMF exposure. This finding inspires future studies that aim to explore the non-drug approaches underlying EMF stimulation and other central nervous system (CNS) inflammatory diseases.
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Affiliation(s)
- Gen-Lin He
- Department of Tropical Medicine, Army Medical University, Chongqing, China.,Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Army Medical University, Chongqing, China
| | - Zhen Luo
- Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Ting-Ting Shen
- Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Ze-Ze Wang
- Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Ping Li
- Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Xue Luo
- Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Ju Yang
- Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Yu-Long Tan
- Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Yuan Wang
- Department of Nuclear Medicine, Xi'nan Hospital, Army Medical University, Chongqing, China
| | - Peng Gao
- Key Laboratory of Medical Protection for Electromagnetic Radiation, Ministry of Education, Army Medical University, Chongqing, China
| | - Xue-Sen Yang
- Department of Tropical Medicine, Army Medical University, Chongqing, China.,Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Army Medical University, Chongqing, China
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22
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Zhang Y, He J, Zheng H, Huang S, Lu F. Association of TREM-1, IL-1β, IL-33/ST2, and TLR Expressions With the Pathogenesis of Ocular Toxoplasmosis in Mouse Models on Different Genetic Backgrounds. Front Microbiol 2019; 10:2264. [PMID: 31649630 PMCID: PMC6794992 DOI: 10.3389/fmicb.2019.02264] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 09/17/2019] [Indexed: 12/11/2022] Open
Abstract
Ocular toxoplasmosis (OT) is one of the most common causes of posterior uveitis. The signaling of triggering receptor expressed on myeloid cells (TREM)-1 amplifies inflammation, whereas TREM-2 signaling is anti-inflammatory. IL-1β is a major driver of inflammation during infection. Toll-like receptors (TLRs) play important roles in protective immune response during Toxoplasma gondii infection, and interleukin (IL)-33 receptor (T1/ST2) signaling prevents toxoplasmic encephalitis in mice. However, the pathogenic mechanisms of OT are not yet well elucidated. To investigate the role of TREM-1, TREM-2, IL-1β, IL-33/ST2, and TLRs in OT of susceptible C57BL/6 (B6) and resistant BALB/c mice, both strains of mice were intravitreally infected with 500 tachyzoites of the RH strain of T. gondii. Histopathological analysis showed that T. gondii-infected B6 mice had more severe ocular damage observed by light microscopy, higher number of neutrophil elastase-positive cells in the eyes detected by immunohistochemical staining, more T. gondii tachyzoites in the eyes observed by transmission electron microscopy, and higher mRNA expression levels of tachyzoite-specific surface antigen 1 detected by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) in comparison of T. gondii-infected BALB/c mice. Detected by using qRT-PCR, the mRNA expression levels of TREM-1, IL-1β, IL-33, ST2, TLR11, TLR12, and TLR13 were significantly higher in the eyes of T. gondii-infected B6 mice than those of T. gondii-infected BALB/c mice, whereas the mRNA expression levels of TLR3 and TLR9 were significantly higher in the eyes of T. gondii-infected BALB/c mice than those of T. gondii-infected B6 mice. Correlation analysis showed that significant positive correlations existed between TREM-1 and IL-1β/IL-33/ST2/TLR9/TLR11 in the eyes of B6 mice and existed between TREM-1 and IL-33/ST2/TLR3/TLR9/TLR13 in the eyes of BALB/c mice after ocular T. gondii infection. Our data revealed that, compared with T. gondii-resistant BALB/c mice, ocular T. gondii infection can stimulate higher production of TREM-1, IL-33, ST2, TLR11, TLR12, and TLR13 in the eyes of T. gondii-susceptible B6 mice, however, whether those lead to more severe ocular pathology in the susceptible B6 mice remain to be further studied.
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Affiliation(s)
- Yanxia Zhang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Jian He
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China.,Public Experimental Teaching Center, Sun Yat-sen University, Guangzhou, China
| | - Huanqin Zheng
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Shiguang Huang
- School of Stomatology, Jinan University, Guangzhou, China
| | - Fangli Lu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-sen University, Guangzhou, China
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23
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TREM2 acts as a tumor suppressor in hepatocellular carcinoma by targeting the PI3K/Akt/β-catenin pathway. Oncogenesis 2019; 8:9. [PMID: 30683932 PMCID: PMC6350080 DOI: 10.1038/s41389-018-0115-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 12/03/2018] [Accepted: 12/20/2018] [Indexed: 12/13/2022] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is involved in nonmalignant pathological processes. However, TREM2’s function in malignant diseases, especially in hepatocellular carcinoma (HCC) remains unknown. In the present study, we report that TREM2 is a novel tumor suppressor in HCC. TREM2 expression was obviously decreased in hepatoma cells (especially metastatic HCC cells), and in most human HCC tissues (especially extrahepatic metastatic tumors). Reduced tumor TREM2 expression was correlated with poor prognosis of HCC patients, and with aggressive pathological features (BCLC stage, tumor size, tumor encapsulation, vascular invasion, and tumor differentiation). TREM2 knockdown substantially promoted cell growth, migration, and invasion in vitro and in vivo, while TREM2 overexpression produced the opposite effect. TREM2 suppressed HCC metastasis by inhibiting epithelial-mesenchymal transition, accompanied by abnormal expression of epithelial and mesenchymal markers. Further study revealed that downregulation of TREM2 in HCC was regulated by miR-31-5p. Moreover, by directly interacting with β-catenin, TREM2 attenuated oncogenic and metastatic behaviors by inhibiting Akt and GSK3β phosphorylation, and activating β-catenin. TREM2 suppressed carcinogenesis and metastasis in HCC by targeting the PI3K/Akt/β-catenin pathway. Thus, we propose that TREM2 may be a candidate prognostic biomarker in malignant diseases and TREM2 restoration might be a prospective strategy for HCC therapy.
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24
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Qin XH, Ma X, Fang SF, Zhang ZZ, Lu JM. IL-17 produced by Th17 cells alleviates the severity of fungal keratitis by suppressing CX43 expression in corneal peripheral vascular endothelial cells. Cell Cycle 2019; 18:274-287. [PMID: 30661459 DOI: 10.1080/15384101.2018.1556059] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Fungal keratitis is a relatively common ocular disease requiring positive medical management combined with surgical intervention. Interleukin-17 (IL-17) was reported to promote the activation and mobilization of neutrophile granulocyte to foci of inflammation. This study investigated the effect of IL-17 production from Th17 cells on the progression of fungal keratitis. A mouse model of fungal keratitis induced by Candida albicans was successfully constructed to detect infiltration of inflammatory cells in corneal tissues by hematoxylin-eosin (HE) staining and immunohistochemistry. Fungal load capacity of mouse cornea was also detected. The regulatory role of IL-17 in fungal keratitis with the involvement of CX43 was investigated with the relevant expression of inflammatory factors detected and activation of vascular endothelial cells assessed. Furthermore, in vivo experiment was also performed to confirm the role of CX43 in keratitis. Mice with fungal keratitis showed increased level of inflammatory cytokines and infiltration of inflammatory cells. Silencing IL-17 in Th17 cells and overexpressing CX43 could inhibit the activation of vascular endothelial cells. Besides, CX43 knockdown in vivo alleviated fungal keratitis in mice. The possible mechanism of the above findings could be IL-17 inhibiting the level of CX43 through the AKT signaling pathway. Taken together, IL-17 could inhibit the occurrence and development of fungal keratitis by suppressing CX43 expression through the AKT signaling pathway. Therefore, this study provides a potential target for the treatment of fungal keratitis.
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Affiliation(s)
- Xiu-Hong Qin
- a Department of Ophthalmology , The First Affiliated Hospital of Dalian Medical University , Dalian , P. R. China
| | - Xiang Ma
- a Department of Ophthalmology , The First Affiliated Hospital of Dalian Medical University , Dalian , P. R. China
| | - Shi-Feng Fang
- a Department of Ophthalmology , The First Affiliated Hospital of Dalian Medical University , Dalian , P. R. China
| | - Zhen-Zhen Zhang
- b Department of Ophthalmology , Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , P. R. China
| | - Jian-Min Lu
- a Department of Ophthalmology , The First Affiliated Hospital of Dalian Medical University , Dalian , P. R. China
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25
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Muraleedharan CK, McClellan SA, Ekanayaka SA, Francis R, Zmejkoski A, Hazlett LD, Xu S. The miR-183/96/182 Cluster Regulates Macrophage Functions in Response to Pseudomonas aeruginosa. J Innate Immun 2019; 11:347-358. [PMID: 30625496 DOI: 10.1159/000495472] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 11/01/2018] [Indexed: 12/13/2022] Open
Abstract
Macrophages (Mϕ) are an important component of the innate immune system; they play critical roles in the first line of defense to pathogen invasion and modulate adaptive immunity. MicroRNAs (miRNAs) are a newly recognized, important level of gene expression regulation. However, their roles in the regulation of Mϕ and the immune system are still not fully understood. In this report, we provide evidence that the conserved miR-183/96/182 cluster (miR-183/96/182) modulates Mϕ function in their production of reactive nitrogen (RNS) and oxygen species (ROS) and their inflammatory response to Pseudomonas aeruginosa (PA) infection and/or lipopolysaccharide (LPS) treatment. We show that knockdown of miR-183/96/182 results in decreased production of multiple proinflammatory cytokines in response to PA or LPS treatment in Mϕ-like Raw264.7 cells. Consistently, peritoneal Mϕ from miR-183/96/182-knockout versus wild-type mice are less responsive to PA or LPS, although their basal levels of proinflammatory cytokines are increased. In addition, overexpression of miR-183/96/182 results in decreased production of nitrite and ROS in Raw264.7 cells. We also provide evidence that DAP12 and Nox2 are downstream target genes of miR-183/96/182. These data suggest that miR-183/96/182 imposes global regulation on various aspects of Mϕ function through different downstream target genes.
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Affiliation(s)
- Chithra K Muraleedharan
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Sharon A McClellan
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Sandamali A Ekanayaka
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Rebecca Francis
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Alex Zmejkoski
- Irvin D. Reed Honors College, Wayne State University, Detroit, Michigan, USA
| | - Linda D Hazlett
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Shunbin Xu
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA,
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26
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Gratuze M, Leyns CEG, Holtzman DM. New insights into the role of TREM2 in Alzheimer's disease. Mol Neurodegener 2018; 13:66. [PMID: 30572908 PMCID: PMC6302500 DOI: 10.1186/s13024-018-0298-9] [Citation(s) in RCA: 258] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 11/28/2018] [Indexed: 12/22/2022] Open
Abstract
Alzheimer's disease (AD) is the leading cause of dementia. The two histopathological markers of AD are amyloid plaques composed of the amyloid-β (Aβ) peptide, and neurofibrillary tangles of aggregated, abnormally hyperphosphorylated tau protein. The majority of AD cases are late-onset, after the age of 65, where a clear cause is still unknown. However, there are likely different multifactorial contributors including age, enviornment, biology and genetics which can increase risk for the disease. Genetic predisposition is considerable, with heritability estimates of 60-80%. Genetic factors such as rare variants of TREM2 (triggering receptor expressed on myeloid cells-2) strongly increase the risk of developing AD, confirming the role of microglia in AD pathogenesis. In the last 5 years, several studies have dissected the mechanisms by which TREM2, as well as its rare variants affect amyloid and tau pathologies and their consequences in both animal models and in human studies. In this review, we summarize increases in our understanding of the involvement of TREM2 and microglia in AD development that may open new therapeutic strategies targeting the immune system to influence AD pathogenesis.
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Affiliation(s)
- Maud Gratuze
- Department of Neurology, St. Louis, USA
- Hope Center for Neurological Disorders, St. Louis, USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Cheryl E. G. Leyns
- Department of Neurology, St. Louis, USA
- Hope Center for Neurological Disorders, St. Louis, USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - David M. Holtzman
- Department of Neurology, St. Louis, USA
- Hope Center for Neurological Disorders, St. Louis, USA
- Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110 USA
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27
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Qu W, Wang Y, Wu Y, Liu Y, Chen K, Liu X, Zou Z, Huang X, Wu M. Triggering Receptors Expressed on Myeloid Cells 2 Promotes Corneal Resistance Against Pseudomonas aeruginosa by Inhibiting Caspase-1-Dependent Pyroptosis. Front Immunol 2018; 9:1121. [PMID: 29887864 PMCID: PMC5980993 DOI: 10.3389/fimmu.2018.01121] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 05/03/2018] [Indexed: 01/16/2023] Open
Abstract
Triggering receptors expressed on myeloid cells 2 (TREM2) is a novel cell surface receptor and functions as an immunomodulatory receptor in infectious diseases. In this study, we investigated the function and regulatory mechanism of TREM2 in Pseudomonas aeruginosa (P. aeruginosa) keratitis. We found that P. aeruginosa keratitis was more severe in Trem2−/− versus wild type C57BL/6 mice as indicated by the increased clinical scores, bacterial load, and cornea pathology. The exacerbated disease progression caused by TREM2 deficiency was associated with boosted activation of caspase-1 and subsequent pyroptosis as well as increased expression of IL-1β. In addition, blockage of pyroptosis by caspase-1 inhibitor not only recovered the severe cornea pathology developed in Trem2−/− mice but also restored the P. aeruginosa clearance suppressed by TREM2 deficiency. Our study demonstrated that TREM2 promotes host resistance against P. aeruginosa keratitis by inhibiting caspase-1-dependent pyroptosis, which provides new insights of TREM2-mediated anti-bacterial immunity.
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Affiliation(s)
- Wenting Qu
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Yi Wang
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Yongjian Wu
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Yiting Liu
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Kang Chen
- Department of Laboratory Medicine, Zhongshan Hospital of Sun Yat-sen University, Zhongshan, China
| | - Xi Liu
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Zhengyu Zou
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Xi Huang
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Minhao Wu
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Diseases Control, Ministry of Education, Sun Yat-sen University, Guangzhou, China.,Guangdong Engineering & Technology Research Center for Disease-Model Animals, Sun Yat-sen University, Guangzhou, China
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28
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Wu Y, Li D, Wang Y, Liu X, Zhang Y, Qu W, Chen K, Francisco NM, Feng L, Huang X, Wu M. Beta-Defensin 2 and 3 Promote Bacterial Clearance of Pseudomonas aeruginosa by Inhibiting Macrophage Autophagy through Downregulation of Early Growth Response Gene-1 and c-FOS. Front Immunol 2018; 9:211. [PMID: 29487594 PMCID: PMC5816924 DOI: 10.3389/fimmu.2018.00211] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 01/24/2018] [Indexed: 01/08/2023] Open
Abstract
Beta-defensins 2 and 3 (BD2 and BD3) are inducible peptides present at the sites of infection, and they are well characterized for their antimicrobial activities and immune-regulatory functions. However, no study has thoroughly investigated their immunomodulatory effects on macrophage-mediated immune responses against Pseudomonas aeruginosa (PA). Here, we use THP-1 and RAW264.7 cell lines and demonstrate that BD2 and BD3 suppressed macrophage autophagy but enhanced the engulfment of PA and Zymosan bioparticles as well as the formation of phagolysosomes, using immunofluorescence staining and confocal microscopy. Plate count assay showed that macrophage-mediated phagocytosis and intracellular killing of PA were promoted by BD2 and BD3. Furthermore, microarray and real-time PCR showed that the expression of two genes, early growth response gene-1 (EGR1) and c-FOS, was attenuated by BD2 and BD3. Western blot revealed that BD2 and BD3 inhibited the expression and nuclear translocation of EGR1 and c-FOS. Knockdown of EGR1 and c-FOS by siRNA transfection suppressed macrophage autophagy before and after PA infection; while overexpression of these two transcription factors enhanced autophagy but reversed the role of BD2 and BD3 on macrophage-mediated PA eradication. Together, these results demonstrate a novel immune defense activity of BD2 and BD3, which promotes clearance of PA by inhibiting macrophage autophagy through downregulation of EGR1 and c-FOS.
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Affiliation(s)
- Yongjian Wu
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Department of Gastroenterology, Guangzhou Women and Children's Medical Center, Guangzhou, China
| | - Dandan Li
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Diseases Control, Sun Yat-sen University, Ministry of Education, Guangzhou, China
| | - Yi Wang
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Diseases Control, Sun Yat-sen University, Ministry of Education, Guangzhou, China
| | - Xi Liu
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Yuanqing Zhang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wenting Qu
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Diseases Control, Sun Yat-sen University, Ministry of Education, Guangzhou, China
| | - Kang Chen
- Division of Clinical Laboratory, Zhongshan Hospital of Sun Yat-sen University, Zhongshan, China
| | - Ngiambudulu M Francisco
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Diseases Control, Sun Yat-sen University, Ministry of Education, Guangzhou, China
| | - Lianqiang Feng
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Diseases Control, Sun Yat-sen University, Ministry of Education, Guangzhou, China
| | - Xi Huang
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Department of Gastroenterology, Guangzhou Women and Children's Medical Center, Guangzhou, China.,Key Laboratory of Tropical Diseases Control, Sun Yat-sen University, Ministry of Education, Guangzhou, China
| | - Minhao Wu
- Program of Pathobiology and Immunology, Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Diseases Control, Sun Yat-sen University, Ministry of Education, Guangzhou, China
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29
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The lipid-sensor TREM2 aggravates disease in a model of LCMV-induced hepatitis. Sci Rep 2017; 7:11289. [PMID: 28900132 PMCID: PMC5595927 DOI: 10.1038/s41598-017-10637-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 08/14/2017] [Indexed: 12/20/2022] Open
Abstract
Lipid metabolism is increasingly being appreciated to affect immunoregulation, inflammation and pathology. In this study we found that mice infected with lymphocytic choriomeningitis virus (LCMV) exhibit global perturbations of circulating serum lipids. Mice lacking the lipid-sensing surface receptor triggering receptor expressed on myeloid cells 2 (Trem2 -/-) were protected from LCMV-induced hepatitis and showed improved virus control despite comparable virus-specific T cell responses. Non-hematopoietic expression of TREM2 was found to be responsible for aggravated hepatitis, indicating a novel role for TREM2 in the non-myeloid compartment. These results suggest a link between virus-perturbed lipids and TREM2 that modulates liver pathogenesis upon viral infection. Targeted interventions of this immunoregulatory axis may ameliorate tissue pathology in hepatitis.
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30
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Ye P, Xu D, Xu J, Liu G, Huang S, Zhang W, Zheng P, Li J, Huang J. TREM-2 negatively regulates LPS-mediated inflammatory response in rat bone marrow-derived MSCs. Mol Med Rep 2017; 16:4777-4783. [PMID: 28849042 PMCID: PMC5647029 DOI: 10.3892/mmr.2017.7212] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 07/27/2017] [Indexed: 12/19/2022] Open
Abstract
To the best of our knowledge, our previous study demonstrated the expression of triggering receptor expressed on myeloid cells 2 (TREM-2) in human bone marrow mesenchymal stem cells (MSCs) for the first time. However, the inflammation regulatory role of TREM-2 in MSCs remain elusive. The aim of the present study was to investigate the immune regulation and the underlying mechanism of TREM-2 in rat bone marrow MSCs. MSCs were divided into three groups: NullMSCs, TREM-2MSCs, and NormMSCs. TREM-2 was expressed in MSCs at the mRNA and protein level. Following stimulation by lipopolysaccharide (LPS), the gene transcription levels of TREM-2 and inflammatory cytokines were increased. The expression levels of inflammatory cytokines, including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), in the TREM-2MSCs lentiviral vector group were significantly downregulated, and the expression of IL-10 was significantly upregulated compared with the controls. Western blot analysis revealed that TREM-2 downregulated the LPS-induced inflammatory response in MSCs, which was probably associated with regulating AKT serine/threonine kinase and p38 mitogen-activated protein kinase downstream signaling proteins. The results of the current study demonstrated that TREM-2 negatively regulates the LPS-mediated inflammatory response in MSCs suggesting that TREM-2 is a potential target of immune regulation in rat MSCs.
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Affiliation(s)
- Pei Ye
- Department of Orthopedics, Sun Yat‑sen Memorial Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China
| | - Dawei Xu
- Department of Orthopedics, Sun Yat‑sen Memorial Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China
| | - Jinhuang Xu
- Department of Orthopedics, Zengcheng People's Hospital of Guangzhou, Guangzhou, Guangdong 511300, P.R. China
| | - Guiwang Liu
- Department of Orthopedics, Sun Yat‑sen Memorial Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China
| | - Shenghui Huang
- Department of Orthopedics, Sun Yat‑sen Memorial Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China
| | - Weiqiong Zhang
- Department of Orthopedics, Zengcheng People's Hospital of Guangzhou, Guangzhou, Guangdong 511300, P.R. China
| | - Peizhong Zheng
- Department of Orthopedics, Zengcheng People's Hospital of Guangzhou, Guangzhou, Guangdong 511300, P.R. China
| | - Jianhua Li
- Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong 510182, P.R. China
| | - Jianrong Huang
- Department of Orthopedics, Sun Yat‑sen Memorial Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510120, P.R. China
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Jay TR, von Saucken VE, Landreth GE. TREM2 in Neurodegenerative Diseases. Mol Neurodegener 2017; 12:56. [PMID: 28768545 PMCID: PMC5541421 DOI: 10.1186/s13024-017-0197-5] [Citation(s) in RCA: 252] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/20/2017] [Indexed: 12/12/2022] Open
Abstract
TREM2 variants have been identified as risk factors for Alzheimer's disease (AD) and other neurodegenerative diseases (NDDs). Because TREM2 encodes a receptor exclusively expressed on immune cells, identification of these variants conclusively demonstrates that the immune response can play an active role in the pathogenesis of NDDs. These TREM2 variants also confer the highest risk for developing Alzheimer's disease of any risk factor identified in nearly two decades, suggesting that understanding more about TREM2 function could provide key insights into NDD pathology and provide avenues for novel immune-related NDD biomarkers and therapeutics. The expression, signaling and function of TREM2 in NDDs have been extensively investigated in an effort to understand the role of immune function in disease pathogenesis and progression. We provide a comprehensive review of our current understanding of TREM2 biology, including new insights into the regulation of TREM2 expression, and TREM2 signaling and function across NDDs. While many open questions remain, the current body of literature provides clarity on several issues. While it is still often cited that TREM2 expression is decreased by pro-inflammatory stimuli, it is now clear that this is true in vitro, but inflammatory stimuli in vivo almost universally increase TREM2 expression. Likewise, while TREM2 function is classically described as promoting an anti-inflammatory phenotype, more than half of published studies demonstrate a pro-inflammatory role for TREM2, suggesting that its role in inflammation is much more complex. Finally, these components of TREM2 biology are applied to a discussion of how TREM2 impacts NDD pathologies and the latest assessment of how these findings might be applied to immune-directed clinical biomarkers and therapeutics.
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Affiliation(s)
- Taylor R. Jay
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA
| | - Victoria E. von Saucken
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W 15th Street, Indianapolis, IN 46202 USA
| | - Gary E. Landreth
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W 15th Street, Indianapolis, IN 46202 USA
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Kober DL, Brett TJ. TREM2-Ligand Interactions in Health and Disease. J Mol Biol 2017; 429:1607-1629. [PMID: 28432014 DOI: 10.1016/j.jmb.2017.04.004] [Citation(s) in RCA: 137] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 01/04/2023]
Abstract
The protein triggering receptor expressed on myeloid cells-2 (TREM2) is an immunomodulatory receptor with a central role in myeloid cell activation and survival. In recent years, the importance of TREM2 has been highlighted by the identification of coding variants that increase risk for Alzheimer's disease and other neurodegenerative diseases. Animal studies have further shown the importance of TREM2 in neurodegenerative and other inflammatory disease models including chronic obstructive pulmonary disease, multiple sclerosis, and stroke. A mechanistic understanding of TREM2 function remains elusive, however, due in part to the absence of conclusive information regarding the identity of endogenous TREM2 ligands. While many TREM2 ligands have been proposed, their physiological role and mechanism of engagement remain to be determined. In this review, we highlight the suggested roles of TREM2 in these diseases and the recent advances in our understanding of TREM2 and discuss putative TREM2-ligand interactions and their potential roles in signaling during health and disease. We develop a model based on the TREM2 structure to explain how different TREM2 ligands might interact with the receptor and how disease risk variants may alter ligand interactions. Finally, we propose future experimental directions to establish the role and importance of these different interactions on TREM2 function.
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Affiliation(s)
- Daniel L Kober
- Molecular Microbiology and Microbial Pathogenesis Program, Washington University School of Medicine, St. Louis, MO 63110, USA; Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tom J Brett
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Zhou X, Wang Y, Wang Y, Cipriano P, Xiao B, Zhou W. Inhibition of triggering receptor expressed on myeloid cells-1 ameliorates experimental autoimmune neuritis. Mol Med Rep 2017; 15:1565-1570. [PMID: 28260057 PMCID: PMC5365016 DOI: 10.3892/mmr.2017.6167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 12/15/2016] [Indexed: 12/30/2022] Open
Abstract
Experimental autoimmune neuritis (EAN) is a cluster of differentiation 4+ T helper 1 cell-mediated inflammatory demyelinating disease of the peripheral nervous system and serves as a useful animal model for Guillain‑Barré syndrome. Triggering receptor expressed on myeloid cells‑1 (TREM‑1) is an important receptor involved in sepsis and the innate inflammatory response. Linear plasmid 17 (LP 17) peptide is a competitive antagonist of TREM‑1. To investigate the role of TREM‑1 in EAN, 64 male Lewis rats were randomly divided into four groups: Normal saline, complete Freund's adjuvant, EAN and LP 17. The present study assessed the mRNA expression levels of TREM‑1, tumor necrosis factor‑α and interleukin‑1β in sciatic nerves and peripheral blood mononuclear cells. The results demonstrated that inhibiting TREM-1 by administering LP 17 ameliorated symptoms and reduced inflammation in EAN rats. The present study concluded that TREM‑1 may be involved in the pathogenesis of EAN, and that inhibition of TREM-1 may ameliorate EAN.
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Affiliation(s)
- Xiaoliang Zhou
- Department of Neurology, Xiangya Hospital, Central‑South University, Changsha, Hunan 410008, P.R. China
| | - Yanli Wang
- Department of Neurology, Jingzhou Central Hospital, Jingzhou, Hubei 434020, P.R. China
| | - Yuzhong Wang
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, Shandong 272000, P.R. China
| | - Peter Cipriano
- Department of Radiology, Stanford Medical Center, Stanford, CA 94305, USA
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central‑South University, Changsha, Hunan 410008, P.R. China
| | - Wenbin Zhou
- Department of Neurology, Xiangya Hospital, Central‑South University, Changsha, Hunan 410008, P.R. China
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TREM2 Promotes Microglial Survival by Activating Wnt/β-Catenin Pathway. J Neurosci 2017; 37:1772-1784. [PMID: 28077724 DOI: 10.1523/jneurosci.2459-16.2017] [Citation(s) in RCA: 199] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 12/26/2016] [Accepted: 01/05/2017] [Indexed: 11/21/2022] Open
Abstract
Triggering Receptor Expressed on Myeloid cells 2 (TREM2), which is expressed on myeloid cells including microglia in the CNS, has recently been identified as a risk factor for Alzheimer's disease (AD). TREM2 transmits intracellular signals through its transmembrane binding partner DNAX-activating protein 12 (DAP12). Homozygous mutations inactivating TREM2 or DAP12 lead to Nasu-Hakola disease; however, how AD risk-conferring variants increase AD risk is not clear. To elucidate the signaling pathways underlying reduced TREM2 expression or loss of function in microglia, we respectively knocked down and knocked out the expression of TREM2 in in vitro and in vivo models. We found that TREM2 deficiency reduced the viability and proliferation of primary microglia, reduced microgliosis in Trem2-/- mouse brains, induced cell cycle arrest at the G1/S checkpoint, and decreased the stability of β-catenin, a key component of the canonical Wnt signaling pathway responsible for maintaining many biological processes, including cell survival. TREM2 stabilized β-catenin by inhibiting its degradation via the Akt/GSK3β signaling pathway. More importantly, treatment with Wnt3a, LiCl, or TDZD-8, which activates the β-catenin-mediated Wnt signaling pathway, rescued microglia survival and microgliosis in Trem2-/- microglia and/or in Trem2-/- mouse brain. Together, our studies demonstrate a critical role of TREM2-mediated Wnt/β-catenin pathway in microglial viability and suggest that modulating this pathway therapeutically may help to combat the impaired microglial survival and microgliosis associated with AD.SIGNIFICANCE STATEMENT Mutations in the TREM2 (Triggering Receptor Expressed on Myeloid cells 2) gene are associated with increased risk for Alzheimer's disease (AD) with effective sizes comparable to that of the apolipoprotein E (APOE) ε4 allele, making it imperative to understand the molecular pathway(s) underlying TREM2 function in microglia. Our findings shed new light on the relationship between TREM2/DNAX-activating protein 12 (DAP12) signaling and Wnt/β-catenin signaling and provide clues as to how reduced TREM2 function might impair microglial survival in AD pathogenesis. We demonstrate that TREM2 promotes microglial survival by activating the Wnt/β-catenin signaling pathway and that it is possible to restore Wnt/β-catenin signaling when TREM2 activity is disrupted or reduced. Therefore, we demonstrate the potential for manipulating the TREM2/β-catenin signaling pathway for the treatment of AD.
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Guo L, Dong W, Fu X, Lin J, Dong Z, Tan X, Zhang T. Tripartite Motif 8 (TRIM8) Positively Regulates Pro-inflammatory Responses in Pseudomonas aeruginosa-Induced Keratitis Through Promoting K63-Linked Polyubiquitination of TAK1 Protein. Inflammation 2016; 40:454-463. [DOI: 10.1007/s10753-016-0491-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wang XC, Zhao GQ, Lin J, Li C, Jiang N, Zhang J. Effects of retinoic acid receptor-γ on the Aspergillus fumigatus induced innate immunity response in human corneal epithelial cells. Int J Ophthalmol 2016; 9:1713-1718. [PMID: 28003968 DOI: 10.18240/ijo.2016.12.02] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 07/28/2016] [Indexed: 11/23/2022] Open
Abstract
AIM To explore the effects of retinoic acid receptor-γ (RARγ) on innate immune responses against Aspergillus fumigatus (A. fumigatus) in cultured human corneal epithelial cells (HCECs). METHODS The HCECs were stimulated with A. fumigatus hyphae for 0, 2, 4, 8, 12 and 16h. RARγ mRNA and protein levels were tested by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Then HCECs were pretreated with or without BMS961 (RARγ agonist, 1 µg/mL). The mRNA and protein expression of Dectin-1 and the downstream cytokines (TNF-α and IL-6) were determined by qRT-PCR, Western blot and enzyme-linked immunosorbent assay (ELISA). RESULTS The expression of RARγ was upregulated after stimulation with A. fumigatus. RARγ mRNA began to rise at 4h and peaked at 8h (P<0.001). The protein of RARγ reached to the peak at 16h (P<0.001). Pretreated with BMS961 before A. fumigatus hyphae stimulation, expression of Dectin-1, TNF-α and IL-6 decreased dramatically at mRNA and protein levels. CONCLUSION HCECs can express RARγ and A. fumigatus hyphae infection can increase RARγ expression. BMS961 can inhibit the expression of Dectin-1 and pro-inflammatory cytokines, and play an anti-inflammatory role in innate immune responses against A. fumigatus.
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Affiliation(s)
- Xiao-Chen Wang
- Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Gui-Qiu Zhao
- Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Jing Lin
- Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Cui Li
- Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Nan Jiang
- Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Jie Zhang
- Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
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Jiang H, Si Y, Li Z, Huang X, Chen S, Zheng Y, Xu G, Chen X, Chen Y, Liu Y, Xiong H, Huang Q, Liang M, Zhang Z. TREM-2 promotes acquired cholesteatoma-induced bone destruction by modulating TLR4 signaling pathway and osteoclasts activation. Sci Rep 2016; 6:38761. [PMID: 27934908 PMCID: PMC5146948 DOI: 10.1038/srep38761] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 11/07/2016] [Indexed: 02/08/2023] Open
Abstract
Triggering receptor expressed on myeloid cells (TREM) has been broadly studied in inflammatory disease. However, the expression and function of TREM-2 remain undiscovered in acquired cholesteatoma. The expression of TREM-2 was significantly higher in human acquired cholesteatoma than in normal skin from the external auditory canal, and its expression level was positively correlated with the severity of bone destruction. Furthermore, TREM-2 was mainly expressed on dendritic cells (DCs). In human acquired cholesteatoma, the expression of proinflammatory cytokines (IL-1β, TNF-α and IL-6) and matrix metalloproteinases (MMP-2, MMP-8 and MMP-9) were up-regulated, and their expression levels were positively correlated with TREM-2 expression. Osteoclasts were activated in human acquired cholesteatoma. In an animal model, TREM-2 was up-regulated in mice with experimentally acquired cholesteatoma. TREM-2 deficiency impaired the maturation of experimentally acquired cholesteatoma and protected against bone destruction induced by experimentally acquired cholesteatoma. Additional data showed that TREM-2 up-regulated IL-1β and IL-6 expression via TLR4 instead of the TLR2 signaling pathway and promoted MMP-2 and MMP-8 secretion and osteoclast activation in experimentally acquired cholesteatoma. Therefore, TREM-2 might enhance acquired cholesteatoma-induced bone destruction by amplifying the inflammatory response via TLR4 signaling pathways and promoting MMP secretion and osteoclast activation.
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Affiliation(s)
- Huaili Jiang
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Yu Si
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Zhuohao Li
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Xi Huang
- Department of Immunology, Institute of Human Virology, Zhongshan School of Medicine and Key Laboratory of Tropical Diseases Control, Ministry of Education Sun Yat-sen University, Guangzhou, China
| | - Suijun Chen
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Yiqing Zheng
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Guo Xu
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Ximing Chen
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Yubin Chen
- Department of Otolaryngology Head and Neck Surgery, The third affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Yi Liu
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Hao Xiong
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Qiuhong Huang
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Maojin Liang
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
| | - Zhigang Zhang
- Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, China
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Zhang H, Sheng L, Tao J, Chen R, Li Y, Sun Z, Qian W. Depletion of the triggering receptor expressed on myeloid cells 2 inhibits progression of renal cell carcinoma via regulating related protein expression and PTEN-PI3K/Akt pathway. Int J Oncol 2016; 49:2498-2506. [PMID: 27779645 DOI: 10.3892/ijo.2016.3740] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 10/03/2016] [Indexed: 11/05/2022] Open
Abstract
The triggering receptor expressed on myeloid cells 2 (TREM-2) is suggested to be involved in the development of certain human malignancies. However, the functions of TREM-2 in renal cell carcinoma (RCC) are still less known. To reveal the effects of TREM-2 on the RCC progression, we examined the TREM-2 expression in RCC tumor tissues. Then, we analyzed the cell proliferation, cell apoptosis, cell cycle and expression of the relative factors in two selected RCC cell lines post RNA interference. We also analyzed the functions of TREM-2 in an in vivo nude mouse model. We found that, the expression of TREM-2 was abnormally elevated in RCC tumor tissues. Silencing TREM-2 inhibited cell growth, induced G1 phase arrest of cell cycle and cell apoptosis in RCC cells. In vivo, the results showed that depletion of TREM-2 significantly inhibited the ACHN tumor growth in the nude mouse model. The analysis of relative protein factors suggested that silencing TREM-2 downregulated the expression levels of Bcl2 and PCNA, and upregulated the expression levels of Bax and caspase-3 in RCC cell lines. Depletion of TREM-2 inactivated PI3K/Akt pathway through increasing the expression of PTEN. Taken together, TREM-2 acts as an oncogene in the development of RCC and can be considered as a novel therapeutic factor in the treatment of RCC.
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Affiliation(s)
- Haojie Zhang
- Department of Urology, Huadong Hospital, Fudan University, Shanghai, P.R. China
| | - Lu Sheng
- Department of Urology, Huadong Hospital, Fudan University, Shanghai, P.R. China
| | - Jing Tao
- Department of Urology, Huadong Hospital, Fudan University, Shanghai, P.R. China
| | - Ran Chen
- Department of Urology, Huadong Hospital, Fudan University, Shanghai, P.R. China
| | - Yang Li
- Department of Biology, School of Life Science, Anhui Medical University, Hefei, Anhui, P.R. China
| | - Zhongquan Sun
- Department of Urology, Huadong Hospital, Fudan University, Shanghai, P.R. China
| | - Weiqing Qian
- Department of Urology, Huadong Hospital, Fudan University, Shanghai, P.R. China
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Wu Y, Li D, Wang Y, Chen K, Yang K, Huang X, Zhang Y, Wu M. Pseudomonas aeruginosa promotes autophagy to suppress macrophage-mediated bacterial eradication. Int Immunopharmacol 2016; 38:214-22. [PMID: 27295610 DOI: 10.1016/j.intimp.2016.04.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/12/2016] [Accepted: 04/29/2016] [Indexed: 12/15/2022]
Abstract
OBJECTIVES To explore the role of autophagy on macrophage-mediated phagocytosis and intracellular killing of Pseudomonas aeruginosa (PA), a common extracellular bacterium which often causes various opportunistic infections. METHODS Macrophages were infected with PA or stimulated with zymosan bioparticles. Autophagy was tested by fluorescent microscopy and Western blot for LC3. Phagocytosis and killing efficiency were assessed by plate count assay, flow cytometry or immunofluorescent staining. Phagocytic receptor expression, ROS generation and NO production were examined by PCR, flow cytometry and Griess reaction, respectively. RESULTS PA infection induced autophagy activation in both mouse and human macrophages. Induction of autophagy by rapamycin or starvation significantly inhibited PA internalization by downregulating phagocytosis receptor expression, and suppressed intracellular killing of PA via reducing ROS and NO production in macrophages. While knockdown of autophagy molecules ATG7 or Beclin1 enhanced macrophage-mediated phagocytosis and intracellular killing of PA. Additionally, confocal microscopy data showed that induction of autophagy reduced the number of phagosomes and phagolysosomes in macrophages after stimulation with zymosan bioparticles. CONCLUSIONS Our study suggested that PA promotes autophagy to suppress macrophage-mediated bacterial phagocytosis and intracellular killing. These insights demonstrated a novel immune evasion mechanism employed by PA, which may provide potential therapeutic strategies of PA infectious diseases.
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Affiliation(s)
- Yongjian Wu
- Department of Immunology, Institute of Tuberculosis Control, Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Dandan Li
- Department of Clinical Laboratory, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 243000, China
| | - Yi Wang
- Department of Immunology, Institute of Tuberculosis Control, Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Kang Chen
- Department of Immunology, Institute of Tuberculosis Control, Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China; Division of Clinical Laboratory, Zhongshan Hospital of Sun Yat-sen University, Zhongshan 528403, China
| | - Kun Yang
- Department of Immunology, Institute of Tuberculosis Control, Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Xi Huang
- Department of Immunology, Institute of Tuberculosis Control, Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Yuanqing Zhang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China.
| | - Minhao Wu
- Department of Immunology, Institute of Tuberculosis Control, Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China.
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Weehuizen TAF, Hommes TJ, Lankelma JM, de Jong HK, Roelofs JJ, de Vos AF, Colonna M, van der Poll T, Wiersinga WJ. Triggering Receptor Expressed on Myeloid Cells (TREM)-2 Impairs Host Defense in Experimental Melioidosis. PLoS Negl Trop Dis 2016; 10:e0004747. [PMID: 27253382 PMCID: PMC4890812 DOI: 10.1371/journal.pntd.0004747] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 05/07/2016] [Indexed: 12/22/2022] Open
Abstract
Background Triggering receptor expressed on myeloid cells (TREM) -1 and TREM-2 are key regulators of the inflammatory response that are involved in the clearance of invading pathogens. Melioidosis, caused by the "Tier 1" biothreat agent Burkholderia pseudomallei, is a common form of community-acquired sepsis in Southeast-Asia. TREM-1 has been suggested as a biomarker for sepsis and melioidosis. We aimed to characterize the expression and function of TREM-1 and TREM-2 in melioidosis. Methodology/Principal Findings Wild-type, TREM-1/3 (Trem-1/3-/-) and TREM-2 (Trem-2-/-) deficient mice were intranasally infected with live B. pseudomallei and killed after 24, and/or 72 h for the harvesting of lungs, liver, spleen, and blood. Additionally, survival studies were performed. Cellular functions were further analyzed by stimulation and/or infection of isolated cells. TREM-1 and TREM-2 expression was increased both in the lung and liver of B. pseudomallei-infected mice. Strikingly, Trem-2-/-, but not Trem-1/3-/-, mice displayed a markedly improved host defense as reflected by a strong survival advantage together with decreased bacterial loads, less inflammation and reduced organ injury. Cellular responsiveness of TREM-2, but not TREM-1, deficient blood and bone-marrow derived macrophages (BMDM) was diminished upon exposure to B. pseudomallei. Phagocytosis and intracellular killing of B. pseudomallei by BMDM and alveolar macrophages were TREM-1 and TREM-2-independent. Conclusions/Significance We found that TREM-2, and to a lesser extent TREM-1, plays a remarkable detrimental role in the host defense against a clinically relevant Gram-negative pathogen in mice: TREM-2 deficiency restricts the inflammatory response, thereby decreasing organ damage and mortality. Triggering receptor expressed on myeloid cells (TREM)-1 and -2 are receptors on immune cells that act as mediators of the innate immune response. It is thought that TREM-1 amplifies the immune response, while TREM-2 acts as a negative regulator. Previously, we found that TREM-1 is upregulated in melioidosis patients. In contrast, nothing is known on TREM-2 expression and its role in melioidosis. In this study we examined the expression and functional role of both TREM-1 and -2 in a murine melioidosis model. We found that TREM-1 and-2 expression was upregulated during melioidosis. Using our experimental melioidosis model, we observed that Trem-2-/- mice were protected against B.pseudomallei-induced lethality. Trem-2-/- mice demonstrated reduced bacterial loads, inflammation and organ damage compared to wild-type mice in experimental melioidosis. Despite reduced bacterial dissemination of B.pseudomallei to distant organs in Trem-1/3-/ mice-, no differences in survival were found between Trem-1/3-/- and wild-type mice during melioidosis. Lastly, we investigated cellular functions of TREM-1 and TREM-2 and found that TREM-2 deficiency led to decreased cellular responsiveness to B. pseudomallei infection. In conclusion, we found that TREM-2 plays an important role during experimental murine melioidosis. TREM-2-deficiency reduces inflammation and organ damage, thereby improving survival.
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Affiliation(s)
- Tassili A. F. Weehuizen
- Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, the Netherlands
- Center for Experimental and Molecular Medicine (CEMM), Academic Medical Center, Amsterdam, the Netherlands
- * E-mail: ;
| | - Tijmen J. Hommes
- Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, the Netherlands
- Center for Experimental and Molecular Medicine (CEMM), Academic Medical Center, Amsterdam, the Netherlands
| | - Jacqueline M. Lankelma
- Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, the Netherlands
- Center for Experimental and Molecular Medicine (CEMM), Academic Medical Center, Amsterdam, the Netherlands
| | - Hanna K. de Jong
- Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, the Netherlands
- Center for Experimental and Molecular Medicine (CEMM), Academic Medical Center, Amsterdam, the Netherlands
| | | | - Alex F. de Vos
- Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, the Netherlands
- Center for Experimental and Molecular Medicine (CEMM), Academic Medical Center, Amsterdam, the Netherlands
| | - Marco Colonna
- Department of Pathology, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Tom van der Poll
- Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, the Netherlands
- Center for Experimental and Molecular Medicine (CEMM), Academic Medical Center, Amsterdam, the Netherlands
- Department of Medicine, Division of Infectious Diseases, Academic Medical Center, Amsterdam, the Netherlands
| | - W. Joost Wiersinga
- Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, the Netherlands
- Center for Experimental and Molecular Medicine (CEMM), Academic Medical Center, Amsterdam, the Netherlands
- Department of Medicine, Division of Infectious Diseases, Academic Medical Center, Amsterdam, the Netherlands
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Zheng H, Liu CC, Atagi Y, Chen XF, Jia L, Yang L, He W, Zhang X, Kang SS, Rosenberry TL, Fryer JD, Zhang YW, Xu H, Bu G. Opposing roles of the triggering receptor expressed on myeloid cells 2 and triggering receptor expressed on myeloid cells-like transcript 2 in microglia activation. Neurobiol Aging 2016; 42:132-41. [PMID: 27143430 DOI: 10.1016/j.neurobiolaging.2016.03.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 02/14/2016] [Accepted: 03/06/2016] [Indexed: 01/12/2023]
Abstract
Mutations in triggering receptor expressed on myeloid cells 2 (TREM2), which has been proposed to regulate the inflammatory responses and the clearance of apoptotic neurons and/or amyloid-β, are genetically linked to increased risk for late-onset Alzheimer's disease (AD). Interestingly, a missense variant in TREM-like transcript 2 (TREML2), a structurally similar protein encoded by the same gene cluster with TREM2 on chromosome 6, has been shown to protect against AD. However, the molecular mechanisms by which TREM2 and TREML2 regulate the pathogenesis of AD, and their functional relationship, if any, remain unclear. Here, we show that lipopolysaccharide (LPS) stimulation significantly suppressed TREM2 but increased TREML2 expression in mouse brain. Consistent with this in vivo result, LPS or oligomeric amyloid-β treatment down regulated TREM2 but up-regulated TREML2 expression in primary microglia. Most important, modulation of TREM2 or TREML2 levels had opposing effects on inflammatory responses with enhancement or suppression of LPS-induced proinflammatory cytokine gene expression observed on TREM2 or TREML2 down regulation, respectively. In addition, the proliferation of primary microglia was significantly decreased when TREM2 was down regulated, whereas it was increased on TREML2 knockdown. Together, our results suggest that several microglial functions are strictly regulated by TREM2 and TREML2, whose dysfunctions likely contribute to AD pathogenesis by impairing brain innate immunity. Our findings provide novel mechanistic insights into the functions of TREM2 and TREML2 in microglia and have implications on designing new therapeutic strategies to treat AD.
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Affiliation(s)
- Honghua Zheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Chia-Chen Liu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Yuka Atagi
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Xiao-Fen Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Lin Jia
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Longyu Yang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Wencan He
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Xilin Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Silvia S Kang
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | | | - John D Fryer
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA; Neurobiology of Disease Graduate Program, Mayo Clinic, Jacksonville, FL, USA
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China; Degenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China; Degenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
| | - Guojun Bu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China; Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA; Neurobiology of Disease Graduate Program, Mayo Clinic, Jacksonville, FL, USA.
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42
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Aging affects the responsiveness of rat peritoneal macrophages to GM-CSF and IL-4. Biogerontology 2015; 17:359-71. [PMID: 26463212 DOI: 10.1007/s10522-015-9620-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 10/09/2015] [Indexed: 12/21/2022]
Abstract
Macrophages undergo significant functional alterations during aging. The aim of the present study was to investigate changes of rat macrophage functions and response to M1/M2 polarization signals with age. Therefore, resident and thioglycollate-elicited peritoneal macrophages from young (3-month-old) and aged (18-19-month-old) rats were tested for phagocytic capacity and ability to secrete inflammatory mediators following in vitro stimulation with LPS and GM-CSF, and IL-4, prototypic stimulators for classically (M1) and alternatively activated (M2) macrophages, respectively. Aging increased the frequency of monocyte-derived (CCR7+ CD68+) and the most mature (CD163+ CD68+) macrophages within resident and thioglycollate-elicited peritoneal macrophages, respectively. The ability to phagocyte zymosan of none of these two cell subsets was affected by either LPS and GM-CSF or IL-4. The upregulated production of IL-1β, IL-6 and IL-10 and downregulated that of TGF-β was observed in response to LPS in resident and thioglycollate-elicited macrophages from rats of both ages. GM-CSF elevated production of IL-1β and IL-6 in resident macrophages from aged rats and in thioglycollate-elicited macrophages from young rats. Unexpectedly, IL-4 augmented production of proinflammatory mediators, IL-1β and IL-6, in resident macrophages from aged rats. In both resident and thioglycollate-elicited macrophages aging decreased NO/urea ratio, whereas LPS but not GM-SCF, shifted this ratio toward NO in the macrophages from animals of both ages. Conversely, IL-4 reduced NO/urea ratio in resident and thioglycollate-elicited macrophages from young rats only. In conclusion, our study showed that aging diminished GM-CSF-triggered polarization of elicited macrophages and caused paradoxical IL-4-driven polarization of resident macrophages toward proinflammatory M1 phenotype. This age-related deregulation of macrophage inflammatory mediator secretion and phagocytosis in response to M1/M2 activators may lead to the deficient control of infectious and/or inflammatory diseases in advanced age.
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Kaur A, Kumar V, Singh S, Singh J, Upadhyay N, Datta S, Singla S, Kumar V. Toll-like receptor-associated keratitis and strategies for its management. 3 Biotech 2015; 5:611-619. [PMID: 28324534 PMCID: PMC4569616 DOI: 10.1007/s13205-015-0280-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 01/27/2015] [Indexed: 11/16/2022] Open
Abstract
Keratitis is an inflammatory condition, characterized by involvement of corneal tissues. Most recurrent challenge of keratitis is infection. Bacteria, virus, fungus and parasitic organism have potential to cause infection. TLR are an important class of protein which has a major role in innate immune response to combat with pathogens. In last past years, extensive research efforts have provided considerable abundance information regarding the role of TLR in various types of keratitis. This paper focuses to review the recent literature illustrating amoebic, bacterial, fungal and viral keratitis associated with Toll-like receptor molecules and summarize existing thoughts on pathogenesis and treatment besides future probabilities for prevention against TLR-associated keratitis.
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Affiliation(s)
- Amandeep Kaur
- Department of Biotechnology, Lovely Professional University, Phagwara, 144411, Punjab, India
| | - Vijay Kumar
- Department of Chemistry, Lovely Professional University, Phagwara, 144411, Punjab, India
| | - Simranjeet Singh
- Department of Biotechnology, Lovely Professional University, Phagwara, 144411, Punjab, India
| | - Joginder Singh
- Department of Chemistry, Lovely Professional University, Phagwara, 144411, Punjab, India
| | - Niraj Upadhyay
- Department of Chemistry, Lovely Professional University, Phagwara, 144411, Punjab, India.
| | - Shivika Datta
- Department of Zoology, Lovely Professional University, Phagwara, 144411, Punjab, India
| | - Sourav Singla
- Department of Biotechnology, Lovely Professional University, Phagwara, 144411, Punjab, India
| | - Virender Kumar
- Department of Chemistry, Lovely Professional University, Phagwara, 144411, Punjab, India
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Taube MA, del Mar Cendra M, Elsahn A, Christodoulides M, Hossain P. Pattern recognition receptors in microbial keratitis. Eye (Lond) 2015; 29:1399-415. [PMID: 26160532 DOI: 10.1038/eye.2015.118] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 05/31/2015] [Indexed: 12/12/2022] Open
Abstract
Microbial keratitis is a significant cause of global visual impairment and blindness. Corneal infection can be caused by a wide variety of pathogens, each of which exhibits a range of mechanisms by which the immune system is activated. The complexity of the immune response to corneal infection is only now beginning to be elucidated. Crucial to the cornea's defences are the pattern-recognition receptors: Toll-like and Nod-like receptors and the subsequent activation of inflammatory pathways. These inflammatory pathways include the inflammasome and can lead to significant tissue destruction and corneal damage, with the potential for resultant blindness. Understanding the immune mechanisms behind this tissue destruction may enable improved identification of therapeutic targets to aid development of more specific therapies for reducing corneal damage in infectious keratitis. This review summarises current knowledge of pattern-recognition receptors and their downstream pathways in response to the major keratitis-causing organisms and alludes to potential therapeutic approaches that could alleviate corneal blindness.
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Affiliation(s)
- M-A Taube
- Division of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK.,University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - M del Mar Cendra
- Division of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - A Elsahn
- Division of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK.,University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - M Christodoulides
- Division of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - P Hossain
- Division of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK.,University Hospital Southampton NHS Foundation Trust, Southampton, UK
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Peng XD, Zhao GQ, Lin J, Jiang N, Xu Q, Zhu CC, Qu JQ, Cong L, Li H. Fungus induces the release of IL-8 in human corneal epithelial cells, via Dectin-1-mediated protein kinase C pathways. Int J Ophthalmol 2015; 8:441-7. [PMID: 26085988 DOI: 10.3980/j.issn.2222-3959.2015.03.02] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/05/2015] [Indexed: 12/11/2022] Open
Abstract
AIM To identify whether Aspergillus fumigatus (A. fumigatus) hyphae antigens induced the release of interleukin-8 (IL-8) in anti-fungal innate immunity of cultured human corneal epithelial cells (HCECs) and determine the involvement of intracellular signalling pathways. METHODS HCECs were treated with A. fumigatus hyphae antigens with different concentrations and time. The cytoplasmic calcium of HCECs were assessed by fluorescence imaging. Western blot was used to detect the expression of Ca(2+)-dependent protein kinase C (PKC). The IL-8 levels were determined by specific human IL-8 enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR). Using a series of pharmacological inhibitors, we examined the upstream signalling pathway responsible for IL-8 expression in response to A. fumigatus hyphae antigens. RESULTS Cells exposed to A. fumigatus hyphae antigens showed higher level of IL-8 mRNA expression and protein production. We demonstrated here that stimulation of HCECs with A. fumigatus hyphae triggers an intracellular Ca(2+) flux and results in the activation of Ca(2+)-dependent PKC (α, βI and βII) which can be attenuated by pre-treatment of cells with laminarin, suggesting that Dectin-1 signals pathway induced cytoplasmic calcium and influence the activation of PKC in HCECs. Inhibitors of Ca(2+)-dependent PKC (Ro-31-8220 and Go6976) significantly abolished hyphae-induced expression of IL-8. CONCLUSION Our findings suggest that A. fumigatus hyphae-induced IL-8 expression was regulated by the activation of Dectin-1-mediated Ca(2+)-dependent PKC in HCECs.
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Affiliation(s)
- Xu-Dong Peng
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Gui-Qiu Zhao
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Jing Lin
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Nan Jiang
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Qiang Xu
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Cheng-Cheng Zhu
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Jian-Qiu Qu
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Lin Cong
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
| | - Hui Li
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, Shandong Province, China
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The importance of the Pseudomonas aeruginosa type III secretion system in epithelium traversal depends upon conditions of host susceptibility. Infect Immun 2015; 83:1629-40. [PMID: 25667266 DOI: 10.1128/iai.02329-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Pseudomonas aeruginosa is invasive or cytotoxic to host cells, depending on the type III secretion system (T3SS) effectors encoded. While the T3SS is known to be involved in disease in vivo, how it participates remains to be clarified. Here, mouse models of superficial epithelial injury (tissue paper blotting with EGTA treatment) and immunocompromise (MyD88 deficiency) were used to study the contribution of the T3SS transcriptional activator ExsA to epithelial traversal. Corneas of excised eyeballs were inoculated with green fluorescent protein (GFP)-expressing PAO1 or isogenic exsA mutants for 6 h ex vivo before bacterial traversal and epithelial thickness were quantified by using imaging. In the blotting-EGTA model, exsA mutants were defective in capacity for traversal. Accordingly, an ∼16-fold variability in exsA expression among PAO1 isolates from three sources correlated with epithelial loss. In contrast, MyD88-/- epithelia remained susceptible to P. aeruginosa traversal despite exsA mutation. Epithelial lysates from MyD88-/- mice had reduced antimicrobial activity compared to those from wild-type mice with and without prior antigen challenge, particularly 30- to 100-kDa fractions, for which mass spectrometry revealed multiple differences, including (i) lower baseline levels of histones, tubulin, and lumican and (ii) reduced glutathione S-transferase, annexin, and dermatopontin, after antigen challenge. Thus, the importance of ExsA in epithelial traversal by invasive P. aeruginosa depends on the compromise enabling susceptibility, suggesting that strategies for preventing infection will need to extend beyond targeting the T3SS. The data also highlight the importance of mimicking conditions allowing susceptibility in animal models and the need to monitor variability among bacterial isolates from different sources, even for the same strain.
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Gawish R, Martins R, Böhm B, Wimberger T, Sharif O, Lakovits K, Schmidt M, Knapp S. Triggering receptor expressed on myeloid cells-2 fine-tunes inflammatory responses in murine Gram-negative sepsis. FASEB J 2014; 29:1247-57. [PMID: 25477281 DOI: 10.1096/fj.14-260067] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 11/13/2014] [Indexed: 12/18/2022]
Abstract
During infections, TLR-mediated responses require tight regulation to allow for pathogen removal, while preventing overwhelming inflammation and immunopathology. The triggering receptor expressed on myeloid cells (TREM)-2 negatively regulates inflammation by macrophages and impacts on phagocytosis, but the function of endogenous TREM-2 during infections is poorly understood. We investigated TREM-2's role in regulating TLR4-mediated inflammation by studying wild-type and TREM-2(-/-) mice challenged with LPS and found TREM-2 to dampen early inflammation. Augmented early inflammation in TREM-2(-/-) animals was followed by an accelerated resolution and ultimately improved survival, associated with the induction of the negative regulator A20. Upon infection with Escherichia coli, the otherwise beneficial effect of an exaggerated early immune response in TREM-2(-/-) animals was counteracted by a 50% reduction in bacterial phagocytosis. In line with this, TREM-2(-/-) peritoneal macrophages (PMs) exhibited augmented inflammation following TLR4 stimulation, demonstrating the presence and negative regulatory functionality of TREM-2 on primary PMs. Significantly, we identified a high turnover rate because TREM-2 RNA is 25-fold down-regulated and the protein proteasomally degraded upon LPS encounter, thus ensuring a tightly regulated and versatile system that modulates inflammation. Our results illustrate TREM-2's effects on infection-triggered inflammation and identify TREM-2 as a potential target to prevent overwhelming inflammation while preserving antibacterial-effector functions.
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Affiliation(s)
- Riem Gawish
- *Ce-M-M-, Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Medicine I, Laboratory of Infection Biology, Medical University of Vienna, Vienna, Austria; and National Food Institute, Division for Epidemiology and Microbial Genomics, Technical University of Denmark, Lyngby, Denmark
| | - Rui Martins
- *Ce-M-M-, Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Medicine I, Laboratory of Infection Biology, Medical University of Vienna, Vienna, Austria; and National Food Institute, Division for Epidemiology and Microbial Genomics, Technical University of Denmark, Lyngby, Denmark
| | - Benedikta Böhm
- *Ce-M-M-, Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Medicine I, Laboratory of Infection Biology, Medical University of Vienna, Vienna, Austria; and National Food Institute, Division for Epidemiology and Microbial Genomics, Technical University of Denmark, Lyngby, Denmark
| | - Terje Wimberger
- *Ce-M-M-, Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Medicine I, Laboratory of Infection Biology, Medical University of Vienna, Vienna, Austria; and National Food Institute, Division for Epidemiology and Microbial Genomics, Technical University of Denmark, Lyngby, Denmark
| | - Omar Sharif
- *Ce-M-M-, Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Medicine I, Laboratory of Infection Biology, Medical University of Vienna, Vienna, Austria; and National Food Institute, Division for Epidemiology and Microbial Genomics, Technical University of Denmark, Lyngby, Denmark
| | - Karin Lakovits
- *Ce-M-M-, Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Medicine I, Laboratory of Infection Biology, Medical University of Vienna, Vienna, Austria; and National Food Institute, Division for Epidemiology and Microbial Genomics, Technical University of Denmark, Lyngby, Denmark
| | - Mariane Schmidt
- *Ce-M-M-, Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Medicine I, Laboratory of Infection Biology, Medical University of Vienna, Vienna, Austria; and National Food Institute, Division for Epidemiology and Microbial Genomics, Technical University of Denmark, Lyngby, Denmark
| | - Sylvia Knapp
- *Ce-M-M-, Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Medicine I, Laboratory of Infection Biology, Medical University of Vienna, Vienna, Austria; and National Food Institute, Division for Epidemiology and Microbial Genomics, Technical University of Denmark, Lyngby, Denmark
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Huang FC. Differential regulation of interleukin-8 and human beta-defensin 2 in Pseudomonas aeruginosa-infected intestinal epithelial cells. BMC Microbiol 2014; 14:275. [PMID: 25433669 PMCID: PMC4261737 DOI: 10.1186/s12866-014-0275-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 10/24/2014] [Indexed: 01/05/2023] Open
Abstract
Background The human opportunistic pathogen, Pseudomonas aeruginosa (P. aeruginosa) carries the highest case fatality rate of all gram-negative infections. Unfortunately, antimicrobial therapy has not been demonstrated to improve clinical outcome and the emergence of multidrug resistant P. aeruginosa has become a major concern in the hospital setting. Fever and diarrhea are the two most common initial symptoms in P. aeruginosa sepsis in previously healthy infants and children. This implies that intestinal epithelial cells in first contact with the pathogen may play an important role in innate immunity to P. aeruginosa infection. Human beta–defensins-2 (hBD-2) and interleukin-8 (IL-8) are crucial for host defense at mucosa but IL-8 may give rise to characteristic pathology of colitis. Results Pseudomonas aeruginosa strain PAO1 was used to infect SW480, an intestinal epithelial cell. IL-8 and hBD-2 mRNA expression and protein secretion were then assessed in SW480 cells using RT-PCR and enzyme-linked immunosorbent assay (ELISA), respectively. Intracellular signaling pathways and nucleotide-binding oligomerization domain (NOD) 1 protein expression were analyzed by Western blot in SW480 cells in the presence or absence of inhibitors or transfected with siRNA. We demonstrate that prolonged infection by P. aeruginosa results in suppression of IL-8 but enhancement of hBD-2, either protein secretion and mRNA expression, in SW480 cells. Inhibitors of ERK suppressed but inhibitor of PI3K enhanced P. aeruginosa-induced IL-8 mRNA expression in SW480 cells while both signaling had no effect on P. aeruginosa-induced hBD-2 expression in SW480 cells. On the other hand, NOD 1 was illustrated to get involved in P. aeruginosa-induced hBD-2 mRNA expression and protein production in SW480 cells. Conclusions The P. aeruginosa-induced antimicrobial peptide in IECs continuously protect the host against prolonged infection, while modulation of proinflammatory responses prevents the host from the detrimental effects of overwhelming inflammation. Thus, P. aeruginosa-induced innate immunity in IECs represents a host protective mechanism, which may provide new insight into the pathogenesis of inflammatory bowel diseases. Electronic supplementary material The online version of this article (doi:10.1186/s12866-014-0275-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Fu-Chen Huang
- Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, 123, Ta-pei Road, Niao-sung District, Kaohsiung, Taiwan.
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Li X, Melief E, Postupna N, Montine KS, Keene CD, Montine TJ. Prostaglandin E2 receptor subtype 2 regulation of scavenger receptor CD36 modulates microglial Aβ42 phagocytosis. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 185:230-9. [PMID: 25452117 DOI: 10.1016/j.ajpath.2014.09.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 09/14/2014] [Accepted: 09/18/2014] [Indexed: 12/18/2022]
Abstract
Recent studies underline the potential relevance of microglial innate immune activation in Alzheimer disease. Primary mouse microglia that lack prostaglandin E2 receptor subtype 2 (EP2) show decreased innate immune-mediated neurotoxicity and increased amyloid β (Aβ) peptide phagocytosis, features that were replicated in vivo. Here, we tested the hypothesis that scavenger receptor CD36 is an effector of EP2-regulated Aβ phagocytosis. CD36 expression was 143-fold greater in mouse primary microglia than in primary astrocytes. Three different means of suppressing EP2 signaling increased and an agonist of EP2 decreased CD36 expression in primary wild-type microglia. Activation of Toll-like receptor (TLR) 3, TLR4, and TLR7, but not TLR2 or TLR9, reduced primary microglial CD36 transcription and cell surface CD36 protein and reduced Aβ42 phagocytosis as well. At each step, the effects of innate immune activation on CD36 were reversed by at least 50% by an EP2 antagonist, and this partial rescue of microglia Aβ42 phagocytosis was largely mediated by CD36 activity. Finally, we showed in hippocampus of wild-type mice that innate immune activation suppressed CD36 expression by an EP2-dependent mechanism. Taken together with results of others that found brain clearance of Aβ peptides and behavioral improvements mediated by CD36 in mice, regulation of CD36-mediated Aβ phagocytosis by suppression of EP2 signaling may provide a new approach to suppressing some aspects of Alzheimer disease pathogenesis.
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Affiliation(s)
- Xianwu Li
- Department of Pathology, University of Washington, Seattle, Washington.
| | - Erica Melief
- Department of Pathology, University of Washington, Seattle, Washington
| | - Nadia Postupna
- Department of Pathology, University of Washington, Seattle, Washington
| | | | - C Dirk Keene
- Department of Pathology, University of Washington, Seattle, Washington
| | - Thomas J Montine
- Department of Pathology, University of Washington, Seattle, Washington
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Zhang Y, Wu J, Xin Z, Wu X. Aspergillus fumigatus triggers innate immune response via NOD1 signaling in human corneal epithelial cells. Exp Eye Res 2014; 127:170-8. [PMID: 25108222 DOI: 10.1016/j.exer.2014.07.025] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 07/07/2014] [Accepted: 07/29/2014] [Indexed: 01/23/2023]
Abstract
Fungal keratitis is a serious vision-threatening disease caused by fungi after corneal epithelium damage. We have previously shown a role of cell surface TLRs in Aspergillus fumigatus (A. fumigatus) keratitis. In the present study we showed that Human telomerase-immortalized corneal epithelial cells (HCECs) exposed to A. fumigatus elicited an inflammatory response consisting in increased interleukin-6 (IL-6), IL-8 and tumor necrosis factor (TNF)-α expression and innate defense molecules hBD2 and LL37 in a time-dependent manner. In this study we further investigated the role of intracellular nucleotide-binding oligomerization domain-containing protein (NOD)-like receptors, NOD1 in innate immune and inflammatory response to A. fumigatus. We showed that NOD1 and its downstream signaling molecules RIP2 and NF-κB p65 are expressed in HCECs challenged with either NOD1 specific ligand iE-DAP or A. fumigatus. More importantly, NOD1 knockdown attenuated A. fumigatus-triggered the expression of NOD1, and downstream signaling effectors RIP2 and NF-κB p65, as well as the secretion of IL-6, IL-8 and TNF-α, and the production of hBD2 and LL37. In conclusion, our results demonstrated that NOD1 is a prominent factor of innate immune and inflammatory response in HCECs against A. fumigatus, suggesting that NOD1 might be a potential novel therapeutic target for the treatment of fungal keratitis.
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Affiliation(s)
- Yuting Zhang
- Department of Ophthalmology, Qilu Hospital of Shandong University, Wenhua Xi Road 107, Jinan, Shandong Province, 250012, PR China
| | - Jiayin Wu
- Department of Ophthalmology, Qilu Hospital of Shandong University, Wenhua Xi Road 107, Jinan, Shandong Province, 250012, PR China
| | - Zhaoting Xin
- Department of Ophthalmology, Qilu Hospital of Shandong University, Wenhua Xi Road 107, Jinan, Shandong Province, 250012, PR China
| | - Xinyi Wu
- Department of Ophthalmology, Qilu Hospital of Shandong University, Wenhua Xi Road 107, Jinan, Shandong Province, 250012, PR China.
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