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Ashenafi S, Brighenti S. Reinventing the human tuberculosis (TB) granuloma: Learning from the cancer field. Front Immunol 2022; 13:1059725. [PMID: 36591229 PMCID: PMC9797505 DOI: 10.3389/fimmu.2022.1059725] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022] Open
Abstract
Tuberculosis (TB) remains one of the deadliest infectious diseases in the world and every 20 seconds a person dies from TB. An important attribute of human TB is induction of a granulomatous inflammation that creates a dynamic range of local microenvironments in infected organs, where the immune responses may be considerably different compared to the systemic circulation. New and improved technologies for in situ quantification and multimodal imaging of mRNA transcripts and protein expression at the single-cell level have enabled significantly improved insights into the local TB granuloma microenvironment. Here, we review the most recent data on regulation of immunity in the TB granuloma with an enhanced focus on selected in situ studies that enable spatial mapping of immune cell phenotypes and functions. We take advantage of the conceptual framework of the cancer-immunity cycle to speculate how local T cell responses may be enhanced in the granuloma microenvironment at the site of Mycobacterium tuberculosis infection. This includes an exploratory definition of "hot", immune-inflamed, and "cold", immune-excluded TB granulomas that does not refer to the level of bacterial replication or metabolic activity, but to the relative infiltration of T cells into the infected lesions. Finally, we reflect on the current knowledge and controversy related to reactivation of active TB in cancer patients treated with immune checkpoint inhibitors such as PD-1/PD-L1 and CTLA-4. An understanding of the underlying mechanisms involved in the induction and maintenance or disruption of immunoregulation in the TB granuloma microenvironment may provide new avenues for host-directed therapies that can support standard antibiotic treatment of persistent TB disease.
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Affiliation(s)
- Senait Ashenafi
- Department of Medicine Huddinge, Center for Infectious Medicine (CIM), Karolinska Institutet, ANA Futura, Huddinge, Sweden,Department of Pathology, School of Medicine, College of Health Sciences, Tikur Anbessa Specialized Hospital and Addis Ababa University, Addis Ababa, Ethiopia
| | - Susanna Brighenti
- Department of Medicine Huddinge, Center for Infectious Medicine (CIM), Karolinska Institutet, ANA Futura, Huddinge, Sweden,*Correspondence: Susanna Brighenti,
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Gazi U, Ozkayalar H, Mujahed MIM, Tosun O, Dalkan C, Sanlidag B, Asım Safak M, Mocan G, Onder Bahceciler N. Altered tonsillar toll-like receptor (TLR)-1 and TLR-2 expression levels between periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis (PFAPA), and group A beta-hemolytic streptococcal (GAβHS) recurrent tonsillitis patients. Int J Pediatr Otorhinolaryngol 2021; 144:110674. [PMID: 33725589 DOI: 10.1016/j.ijporl.2021.110674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/16/2021] [Accepted: 03/07/2021] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Tonsillar microenvironment is thought to contribute to innate immune dysregulation responsible for the periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) because of beneficial effects of tonsillectomy on treatment of the syndrome. Accordingly previous studies reported altered lymphocyte frequency, cytokine level and microbial composition in PFAPA tonsils. The aim of our study is to monitor expression levels of pro-inflammatory cell surface Toll-like receptors (TLRs) which have important role in induction of inflammation and maintaining tissue haemostasis. MATERIALS AND METHODS Seven patients with PFAPA syndrome, and eight patients with group A beta-hemolytic streptococcal (GAβHS) recurrent tonsillitis were included in our study. Tonsillar expression levels of TLR-1, -2, -4, -5, and -6 were monitored by immunohistochemistry (IHC). Expression levels were scored using semi-quantitative analysis method and were statistically analyzed by Two-Way Repeated Measures Analysis of Variance test. RESULTS IHC analysis demonstrated expression of all TLRs in tonsillar surface epithelium (SE) and lymphoid interior (LI) except for TLR-6 which was not present in the former. There has not been any statistically significant difference in TLR expression levels between PFAPA and GAβHS tonsils, except for TLR-1 and TLR-2 which were higher on LI and lower on SE of PFAPA tonsils, respectively, than that of the GAβHS samples. CONCLUSIONS Altered TLR expression levels may be involved in PFAPA pathogenesis. Future studies with higher patient number, uninflamed tonsils and cellular markers are required to further enlighten the role of TLRs in the development of syndrome.
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Affiliation(s)
- Umut Gazi
- Department of Medical Microbiology and Clinical Microbiology, Faculty of Medicine, Near East University, Nicosia, Cyprus.
| | - Hanife Ozkayalar
- Department of Pathology, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Monjed I M Mujahed
- Department of Medical Microbiology and Clinical Microbiology, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Ozgur Tosun
- Department of Biostatistics, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Ceyhun Dalkan
- Department of Pediatrics, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Burcin Sanlidag
- Department of Pediatrics, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Mustafa Asım Safak
- Department of Otorhinolaryngology, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Gamze Mocan
- Department of Pathology, Faculty of Medicine, Near East University, Nicosia, Cyprus
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Gebremicael G, Kassa D, Alemayehu Y, Gebreegziaxier A, Kassahun Y, van Baarle D, H. M. Ottenhoff T, M. Cliff J, C. Haks M. Gene expression profiles classifying clinical stages of tuberculosis and monitoring treatment responses in Ethiopian HIV-negative and HIV-positive cohorts. PLoS One 2019; 14:e0226137. [PMID: 31821366 PMCID: PMC6903757 DOI: 10.1371/journal.pone.0226137] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 11/20/2019] [Indexed: 12/11/2022] Open
Abstract
Background Validation of previously identified candidate biomarkers and identification of additional candidate gene expression profiles to facilitate diagnosis of tuberculosis (TB) disease and monitoring treatment responses in the Ethiopian context is vital for improving TB control in the future. Methods Expression levels of 105 immune-related genes were determined in the blood of 80 HIV-negative study participants composed of 40 active TB cases, 20 latent TB infected individuals with positive tuberculin skin test (TST+), and 20 healthy controls with no Mycobacterium tuberculosis (Mtb) infection (TST-), using focused gene expression profiling by dual-color Reverse-Transcription Multiplex Ligation-dependent Probe Amplification assay. Gene expression levels were also measured six months after anti-TB treatment (ATT) and follow-up in 38 TB patients. Results The expression of 15 host genes in TB patients could accurately discriminate between TB cases versus both TST+ and TST- controls at baseline and thus holds promise as biomarker signature to classify active TB disease versus latent TB infection in an Ethiopian setting. Interestingly, the expression levels of most genes that markedly discriminated between TB cases versus TST+ or TST- controls did not normalize following completion of ATT therapy at 6 months (except for PTPRCv1, FCGR1A, GZMB, CASP8 and GNLY) but had only fully normalized at the 18 months follow-up time point. Of note, network analysis comparing TB-associated host genes identified in the current HIV-negative TB cohort to TB-associated genes identified in our previously published Ethiopian HIV-positive TB cohort, revealed an over-representation of pattern recognition receptors including TLR2 and TLR4 in the HIV-positive cohort which was not seen in the HIV-negative cohort. Moreover, using ROC cutoff ≥ 0.80, FCGR1A was the only marker with classifying potential between TB infection and TB disease regardless of HIV status. Conclusions Our data indicate that complex gene expression signatures are required to measure blood transcriptomic responses during and after successful ATT to fully diagnose TB disease and characterise drug-induced relapse-free cure, combining genes which resolve completely during the 6-months treatment phase of therapy with genes that only fully return to normal levels during the post-treatment resolution phase.
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Affiliation(s)
- Gebremedhin Gebremicael
- HIV and TB Diseases Research Directorate, Ethiopian Public Health Institute (EPHI), Addis Ababa, Ethiopia
- TB Centre and Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, England, United Kingdom
- * E-mail:
| | - Desta Kassa
- HIV and TB Diseases Research Directorate, Ethiopian Public Health Institute (EPHI), Addis Ababa, Ethiopia
| | - Yodit Alemayehu
- HIV and TB Diseases Research Directorate, Ethiopian Public Health Institute (EPHI), Addis Ababa, Ethiopia
| | - Atsbeha Gebreegziaxier
- HIV and TB Diseases Research Directorate, Ethiopian Public Health Institute (EPHI), Addis Ababa, Ethiopia
| | - Yonas Kassahun
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Debbie van Baarle
- Center for Immunology of Infectious Diseases and Vaccins (IIV), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - Tom H. M. Ottenhoff
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Jacqueline M. Cliff
- TB Centre and Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, England, United Kingdom
| | - Mariëlle C. Haks
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
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Nyúl-Tóth Á, Kozma M, Nagyőszi P, Nagy K, Fazakas C, Haskó J, Molnár K, Farkas AE, Végh AG, Váró G, Galajda P, Wilhelm I, Krizbai IA. Expression of pattern recognition receptors and activation of the non-canonical inflammasome pathway in brain pericytes. Brain Behav Immun 2017; 64:220-231. [PMID: 28432035 DOI: 10.1016/j.bbi.2017.04.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 03/31/2017] [Accepted: 04/12/2017] [Indexed: 12/27/2022] Open
Abstract
Cerebral pericytes are mural cells embedded in the basement membrane of capillaries. Increasing evidence suggests that they play important role in controlling neurovascular functions, i.e. cerebral blood flow, angiogenesis and permeability of the blood-brain barrier. These cells can also influence neuroinflammation which is highly regulated by the innate immune system. Therefore, we systematically tested the pattern recognition receptor expression of brain pericytes. We detected expression of NOD1, NOD2, NLRC5, NLRP1-3, NLRP5, NLRP9, NLRP10 and NLRX mRNA in non-treated cells. Among the ten known human TLRs, TLR2, TLR4, TLR5, TLR6 and TLR10 were found to be expressed. Inflammatory mediators induced the expression of NLRA, NLRC4 and TLR9 and increased the levels of NOD2, TLR2, inflammasome-forming caspases and inflammasome-cleaved interleukins. Oxidative stress, on the other hand, upregulated expression of TLR10 and NLRP9. Activation of selected pattern recognition receptors can lead to inflammasome assembly and caspase-dependent secretion of IL-1β. TNF-α and IFN-γ increased the levels of pro-IL-1β and pro-caspase-1 proteins; however, no canonical activation of NLRP1, NLRP2, NLRP3 or NLRC4 inflammasomes could be observed in human brain vascular pericytes. On the other hand, we could demonstrate secretion of active IL-1β in response to non-canonical inflammasome activation, i.e. intracellular LPS or infection with E. coli bacteria. Our in vitro results indicate that pericytes might have an important regulatory role in neuroinflammation.
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Affiliation(s)
- Ádám Nyúl-Tóth
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Mihály Kozma
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Péter Nagyőszi
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Krisztina Nagy
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Csilla Fazakas
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - János Haskó
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Kinga Molnár
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Attila E Farkas
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Attila G Végh
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - György Váró
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Péter Galajda
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Imola Wilhelm
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary; Institute of Life Sciences, Vasile Goldiş Western University of Arad, Str. Liviu Rebreanu 86, 310414 Arad, Romania.
| | - István A Krizbai
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary; Institute of Life Sciences, Vasile Goldiş Western University of Arad, Str. Liviu Rebreanu 86, 310414 Arad, Romania.
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Vu A, Calzadilla A, Gidfar S, Calderon-Candelario R, Mirsaeidi M. Toll-like receptors in mycobacterial infection. Eur J Pharmacol 2016; 808:1-7. [PMID: 27756604 DOI: 10.1016/j.ejphar.2016.10.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 10/04/2016] [Accepted: 10/14/2016] [Indexed: 10/20/2022]
Abstract
Toll-like receptors are transmembrane glycoproteins predominantly expressed in tissues with immune function. They are considered one of the most important pattern recognition receptor families discovered at the end of 20th century and a key aspect of the innate immune system response to infectious disease. Here we present a review of the current knowledge of individual Toll-like receptors, 1 through 13, with a focus on their role in the immune system response to mycobacterial infection. We present literature to date about the Toll-like receptors structure, localization and expression, signaling pathways, and function. The Toll-like receptor family may have proven an important role in the immune system response to mycobacterial infections, including M. tuberculosis and non-tuberculous (NTM) organisms.
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Affiliation(s)
- Ann Vu
- Department of Medicine, University of Miami, 1600 NW, Miami, FL 33136, USA.
| | - Andrew Calzadilla
- Department of Medicine, University of Miami, 1600 NW, Miami, FL 33136, USA.
| | - Sanaz Gidfar
- Department of Medicine, University of Miami, 1600 NW, Miami, FL 33136, USA.
| | - Rafael Calderon-Candelario
- Division of Pulmonary and Critical Care, University of Miami, 1600 NW, Miami, FL 33136, USA; Miami VA Medical Center, 1201 N.W. 16th St., Miami, FL 33125, USA.
| | - Mehdi Mirsaeidi
- Division of Pulmonary and Critical Care, University of Miami, 1600 NW, Miami, FL 33136, USA; Miami VA Medical Center, 1201 N.W. 16th St., Miami, FL 33125, USA.
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Mortaz E, Adcock IM, Tabarsi P, Masjedi MR, Mansouri D, Velayati AA, Casanova JL, Barnes PJ. Interaction of Pattern Recognition Receptors with Mycobacterium Tuberculosis. J Clin Immunol 2014; 35:1-10. [PMID: 25312698 PMCID: PMC4306732 DOI: 10.1007/s10875-014-0103-7] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 09/26/2014] [Indexed: 12/12/2022]
Abstract
Tuberculosis (TB) is considered a major worldwide health problem with 10 million new cases diagnosed each year. Our understanding of TB immunology has become greater and more refined since the identification of Mycobacterium tuberculosis (MTB) as an etiologic agent and the recognition of new signaling pathways modulating infection. Understanding the mechanisms through which the cells of the immune system recognize MTB can be an important step in designing novel therapeutic approaches, as well as improving the limited success of current vaccination strategies. A great challenge in chronic disease is to understand the complexities, mechanisms, and consequences of host interactions with pathogens. Innate immune responses along with the involvement of distinct inflammatory mediators and cells play an important role in the host defense against the MTB. Several classes of pattern recognition receptors (PRRs) are involved in the recognition of MTB including Toll-Like Receptors (TLRs), C-type lectin receptors (CLRs) and Nod-like receptors (NLRs) linked to inflammasome activation. Among the TLR family, TLR1, TLR2, TLR4, and TLR9 and their down-stream signaling proteins play critical roles in the initiation of the immune response in the pathogenesis of TB. The inflammasome pathway is associated with the coordinated release of cytokines such as IL-1β and IL-18 which also play a role in the pathogenesis of TB. Understanding the cross-talk between these signaling pathways will impact on the design of novel therapeutic strategies and in the development of vaccines and immunotherapy regimes. Abnormalities in PRR signaling pathways regulated by TB will affect disease pathogenesis and need to be elucidated. In this review we provide an update on PRR signaling during M. tuberculosis infection and indicate how greater knowledge of these pathways may lead to new therapeutic opportunities.
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Affiliation(s)
- Esmaeil Mortaz
- Division of Pharmacology and Pathophysiology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Sciences, Utrecht University, Utrecht, The Netherlands.,Cell and Molecular Biology Group, Airways Disease Section, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, Dovehouse Street, London, SW3 6LY, UK.,Clinical Tuberculosis and Epidemiology Research Center, National Research and Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ian M Adcock
- Cell and Molecular Biology Group, Airways Disease Section, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, Dovehouse Street, London, SW3 6LY, UK.
| | - Payam Tabarsi
- Clinical Tuberculosis and Epidemiology Research Center, National Research and Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza Masjedi
- Clinical Tuberculosis and Epidemiology Research Center, National Research and Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Davood Mansouri
- Chronic Respiratory Diseases Research Center and National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ali Akbar Velayati
- Clinical Tuberculosis and Epidemiology Research Center, National Research and Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Jean-Laurent Casanova
- Howard Hughes Medical Institute and St. Giles Laboratory of Human Genetics of Infectious Diseases, The Rockefeller University, New York, 10065, NY, USA.,Paris Descartes Sorbonne Paris Cité University, Imagine Institute, Paris, France.,Laboratory of Human Genetics of Infectious Diseases, INSERM UMR 1163, Imagine Institute, Necker Hospital for Sick Children, Paris, France.,Pediatric Hematology and Immunology Unit, Necker Hospital for Sick Children, AP-HP, Paris, France
| | - Peter J Barnes
- Cell and Molecular Biology Group, Airways Disease Section, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, Dovehouse Street, London, SW3 6LY, UK
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Yamashiro LH, Oliveira SC, Báfica A. Innate immune sensing of nucleic acids from mycobacteria. Microbes Infect 2014; 16:991-7. [PMID: 25284681 DOI: 10.1016/j.micinf.2014.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/03/2014] [Accepted: 09/04/2014] [Indexed: 01/16/2023]
Abstract
Endosomal and cytosolic receptors engage recognition of mycobacterial-derived nucleic acids (MyNAs). In contrast, virulent mycobacteria may utilize nucleic acid recognition pathways to escape the host immune system. This short review will summarize the mechanisms by which MyNAs are sensed and how they influence host protective responses.
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Affiliation(s)
- Lívia Harumi Yamashiro
- Laboratory of Immunobiology, Department of Microbiology, Immunology and Parasitology, Brazil; Pharmacology Graduate Program, Federal University of Santa Catarina, Brazil
| | - Sérgio Costa Oliveira
- Laboratory of Immunology and Infectious Diseases, Federal University of Minas Gerais, Brazil
| | - André Báfica
- Laboratory of Immunobiology, Department of Microbiology, Immunology and Parasitology, Brazil; Pharmacology Graduate Program, Federal University of Santa Catarina, Brazil.
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Promsudthi A, Poomsawat S, Limsricharoen W. The role of Toll-like receptor 2 and 4 in gingival tissues of chronic periodontitis subjects with type 2 diabetes. J Periodontal Res 2013; 49:346-54. [PMID: 23844856 DOI: 10.1111/jre.12112] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2013] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND OBJECTIVE Diabetes is one important risk factor of chronic periodontitis. However, the roles of toll-like receptor (TLR) 2 and TLR4, which are implicated in the inflammatory process in both chronic periodontitis and diabetes, have not been studied. This study aimed to determine whether TLR2 and TLR4 might be involved in the relationship between chronic periodontitis and diabetes by examining TLR2 and TLR4 expression in gingival tissues from subjects with chronic periodontitis without diabetes (CP) and with diabetes (CP+DM) and from periodontally healthy subjects without diabetes (PH) and with diabetes (PH+DM). MATERIAL AND METHODS Gingival tissues were collected from 23 CP subjects, 21 CP+DM subjects, 22 PH subjects and 20 PH+DM subjects. The expression of TLR2 and TLR4 in gingival tissues was determined using an immunohistochemical method. In gingival epithelium, staining patterns and intensity levels of TLR2 and TLR4 expression were studied. In connective tissues, the percentages of TLR2- and TLR4-positive cells were calculated. The intensity levels and the percentages of positive cells were statistically analyzed. RESULTS Chronic periodontitis or diabetes showed no significant effect on TLR2 expression in the oral epithelium. However, diabetes increased the expression of TLR2 in sulcular epithelium and changed the pattern of TLR2 expression in gingival epithelium. Chronic periodontitis decreased the expression of TLR4 in gingival epithelium. In connective tissue under sulcular epithelium, CP+DM subjects showed statistically significant higher percentages of TLR2- and TLR4-positive cells compared with PH and PH+DM subjects. CONCLUSION Our results suggest that hyperglycemia and chronic periodontitis had effects on TLR2 and TLR4 expression in gingival tissue. The differences in TLR2 and TLR4 expression could contribute to a greater inflammatory response, leading to periodontal disease initiation and progression.
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Affiliation(s)
- A Promsudthi
- Department of Oral Medicine and Periodontology, Faculty of Dentistry, Mahidol University, Bangkok, Thailand
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S. D, JA S, KPS K, LM T, DA F, T N, T N, S G, G K. Immunohistological characterization of spinal TB granulomas from HIV-negative and -positive patients. Tuberculosis (Edinb) 2013; 93:432-41. [PMID: 23541388 PMCID: PMC3681883 DOI: 10.1016/j.tube.2013.02.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 01/09/2013] [Accepted: 02/04/2013] [Indexed: 12/21/2022]
Abstract
Tuberculosis (TB) is mainly a disease of the lungs, but Mycobacterium tuberculosis (Mtb) can establish infection in virtually any organ in the body. Rising rates of extrapulmonary (EP) TB have been largely associated with the HIV epidemic, as patients co-infected with HIV show a four-fold higher risk of EPTB. Spinal TB (Pott's Disease), one of the most debilitating extrapulmonary forms of disease, is difficult to diagnose and can cause deformity and/or neurological deficits. This study examined the histopathology and distribution of immune cells within spinal TB lesions and the impact of HIV on pathogenesis. The overall structure of the spinal granulomas resembled that seen in lung lesions from patients with pulmonary TB. Evidence of efficient macrophage activation and differentiation were detectable within organized structures in the spinal tissue, irrespective of HIV status. Interestingly, the granulomatous architecture and macroscopic features were similar in all samples examined, despite a reversal in the ratio of infiltrating CD4 to CD8 T cells in the lesions from HIV-infected patients. This study provides a foundation to understand the mechanism of tissue destruction and disease progression in Spinal TB, enabling the future development of novel therapeutic strategies and diagnostic approaches for this devastating disease.
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Affiliation(s)
- Danaviah S.
- Virology Laboratory, Africa Centre for Health and Population Studies, Doris Duke Medical Research Institute (DDMRI) at the University of KwaZulu-Natal (UKZN), Durban, South Africa, 4013
| | - Sacks JA
- Laboratory of Mycobacterial Immunity and Pathogenesis, Public Health Research Institute (PHRI) at the University of Medicine and Dentistry of New Jersey (UMDNJ), Newark, NJ 07103 , ,
| | - Kumar KPS
- Department of Orthopedic Surgery, Nelson R. Mandela School of Medicine, UKZN, Durban, South Africa, 4013
- Optics and Imaging Centre, DDMRI, UKZN, Durban, South Africa, 4013
| | - Taylor LM
- Laboratory of Mycobacterial Immunity and Pathogenesis, Public Health Research Institute (PHRI) at the University of Medicine and Dentistry of New Jersey (UMDNJ), Newark, NJ 07103 , ,
| | - Fallows DA
- Laboratory of Mycobacterial Immunity and Pathogenesis, Public Health Research Institute (PHRI) at the University of Medicine and Dentistry of New Jersey (UMDNJ), Newark, NJ 07103 , ,
| | - Naicker T
- HIV Pathogenesis Programme, DDMRI, UKZN, Durban, South Africa, 4013
| | - Ndung'u T
- KwaZulu-Natal Research Institute for Tuberculosis and HIV (K-RITH), Nelson R. Mandela School of Medicine, UKZN, Durban, South Africa, 4013
| | - Govender S
- Department of Orthopedic Surgery, Nelson R. Mandela School of Medicine, UKZN, Durban, South Africa, 4013
- Optics and Imaging Centre, DDMRI, UKZN, Durban, South Africa, 4013
| | - Kaplan G
- Laboratory of Mycobacterial Immunity and Pathogenesis, Public Health Research Institute (PHRI) at the University of Medicine and Dentistry of New Jersey (UMDNJ), Newark, NJ 07103 , ,
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Abstract
Autoreactive B and T cells are present in healthy, autoimmunity-free individuals, but they are kept in check by various regulatory mechanisms. In systemic lupus erythematosus (SLE) patients, however, autoreactive cells are expanded, activated, and produce large quantities of autoantibodies, directed especially against nuclear antigens. These antibodies form immune complexes with self-nucleic acids present in SLE serum. Since self-DNA and self-RNA in the form of protein complexes can act as TLR9 and TLR7 ligands, respectively, TLR stimulation is suggested as an additional signal contributing to activation and/or modulation of the aberrant adaptive immune response. Data from mouse models suggest a pathogenic role for TLR7 and a protective role for TLR9 in the pathogenesis of SLE. Future investigations are needed to elucidate the underlying modulatory mechanisms and the role of TLR7 and TLR9 in the complex pathogenesis of human SLE.
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Affiliation(s)
- T Celhar
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, #03 Immunos, Singapore
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Kobayashi T, Kawamura H, Kanda Y, Matsumoto H, Saito S, Takeda K, Kawamura T, Abo T. Natural killer T cells suppress zymosan A-mediated granuloma formation in the liver by modulating interferon-γ and interleukin-10. Immunology 2012; 136:86-95. [PMID: 22268994 DOI: 10.1111/j.1365-2567.2012.03562.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Wild-type (WT) and CD1d(-/-) [without natural killer (NK) T cells] mice were treated with zymosan A to induce granuloma formation in the liver. Increased granuloma formation was seen in NKT-less mice on days 7 and 14 after administration. WT mice showed limited granuloma formation, and zymosan A eventually induced NKT cell accumulation as identified by their surface marker (e.g. CD1d-tetramer). Zymosan A augmented the expression of Toll-like receptor 2 on the cell surface of both macrophages and NKT cells. One possible reason for accelerated granuloma formation in NKT-less mice was increased production of interferon- γ (IFN-γ); a theory that was confirmed using IFN-γ(-/-) mice. Also, zymosan A increased interleukin-10 production in WT mice, which suppresses IFN-γ production. Taken together, these results suggest that NKT cells in the liver have the potential to suppress zymosan A-mediated granuloma formation.
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Affiliation(s)
- Takahiro Kobayashi
- Department of Immunology, Niigata University School of Medicine, Niigata, Japan
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12
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Mortaz E, Varahram M, Farnia P, Bahadori M, Masjedi MR. New Aspects in Immunopathology of Mycobacterium tuberculosis. ACTA ACUST UNITED AC 2012. [DOI: 10.5402/2012/963879] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Our understanding of tuberculosis (TB) pathology and immunology has become extensively deeper and more refined since the identification of Mycobacterium tuberculosis (MTB) as the etiologic agent of disease by Dr. Robert Koch in 1882. A great challenge in chronic disease is to understand the complexities, mechanisms, and consequences of host interactions with pathogens. TB, caused by MTB, is a major health problem in world, with 10 million new cases diagnosed each year. Innate immunity is shown playing an important role in the host defense against the MTB, and the first step in this process is recognition of MTB by cells of the innate immune system. Several classes of pattern recognition receptors (PPRs) are involved in the recognition of MTB, including toll-like receptors (TLRs), C-type lectin receptors (CLRs), and nod-like receptors (NLRs). Among the TLR family, TLR1, TLR2, TLR4, and TLR9 and their down streams, proteins play the most prominent roles in the initiation of the immune response against MTB. Beside of TLRs signaling, recently the activation of inflammasome pathway in the pathogenesis of TB much appreciated. Knowledge about these signaling pathways is crucial for understanding the pathophysiology of TB, on one hand, and for the development of novel strategies of vaccination and treatment such as immunotherapy on the other. Given the critical role of TLRs/inflammasome signaling in innate immunity and initiation of the appropriate adaptive response, the regulation of these pathways is likely to be an important determinant of the clinical outcome of MTB infection. In this review paper we focused on the immune response, which is the recognition of MTB by inflammatory innate immune cells following infection.
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Affiliation(s)
- E. Mortaz
- Chronic Respiratory Disease Research Center, National Research Institute of Tuberculosis and Lung Disease (NRITLD), Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Division of Pharmacology and Pathophysiology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Sciences, Utrecht University, Utrecht, The Netherlands
| | - M. Varahram
- Mycobacteriology Research Centre, National Research Institute of Tuberculosis and Lung Disease, Shahid Beheshti University, Tehran, Iran
| | - P. Farnia
- Mycobacteriology Research Centre, National Research Institute of Tuberculosis and Lung Disease, Shahid Beheshti University, Tehran, Iran
| | - M. Bahadori
- Chronic Respiratory Disease Research Center, National Research Institute of Tuberculosis and Lung Disease (NRITLD), Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - MR Masjedi
- Chronic Respiratory Disease Research Center, National Research Institute of Tuberculosis and Lung Disease (NRITLD), Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Brighenti S, Andersson J. Local immune responses in human tuberculosis: learning from the site of infection. J Infect Dis 2012; 205 Suppl 2:S316-24. [PMID: 22448014 DOI: 10.1093/infdis/jis043] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Host-pathogen interactions in tuberculosis should be studied at the disease site because Mycobacterium tuberculosis is predominately contained in local tissue lesions. Although M. tuberculosis infection involves different clinical forms of tuberculosis, such as pulmonary tuberculosis, pleural tuberculosis, and lymph node tuberculosis, most studies of human tuberculosis are performed using cells from the peripheral blood, which may not provide a proper reflection of the M. tuberculosis-specific immune responses induced at the local site of infection. A very low proportion of M. tuberculosis-specific effector T cells are found in the blood compared with the infected tissue, and thus there may be considerable differences in the cellular immune response and regulatory mechanisms induced in these diverse compartments. In this review, we discuss differences in the immune response at the local site of infection compared with the peripheral circulation. The cell types and immune reactions involved in granuloma formation and maintenance as well as the in situ technologies used to assess local tuberculosis pathogenesis are also described. We need to strengthen and improve the exploratory strategies used to dissect immunopathogenesis in human tuberculosis with the aim to accelerate the implementation of relevant research findings in clinical practice.
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Affiliation(s)
- Susanna Brighenti
- Department of Medicine, Center for Infectious Medicine (CIM), Karolinska Institutet, Karolinska University Hospital Huddinge, 141 86 Stockholm, Sweden.
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Mortaz E, Netea MG, Masjedi MR, Adcock IM. WITHDRAWN: The role of the inflammasome and toll-like receptor signaling the pathogenesis of infection with Mycobacterium tuberculosis. Int J Mycobacteriol 2012. [DOI: 10.1016/j.ijmyco.2012.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Hoppstädter J, Diesel B, Zarbock R, Breinig T, Monz D, Koch M, Meyerhans A, Gortner L, Lehr CM, Huwer H, Kiemer AK. Differential cell reaction upon Toll-like receptor 4 and 9 activation in human alveolar and lung interstitial macrophages. Respir Res 2010; 11:124. [PMID: 20843333 PMCID: PMC2949727 DOI: 10.1186/1465-9921-11-124] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Accepted: 09/15/2010] [Indexed: 01/03/2023] Open
Abstract
Background Investigations on pulmonary macrophages (MΦ) mostly focus on alveolar MΦ (AM) as a well-defined cell population. Characteristics of MΦ in the interstitium, referred to as lung interstitial MΦ (IM), are rather ill-defined. In this study we therefore aimed to elucidate differences between AM and IM obtained from human lung tissue. Methods Human AM and IM were isolated from human non-tumor lung tissue from patients undergoing lung resection. Cell morphology was visualized using either light, electron or confocal microscopy. Phagocytic activity was analyzed by flow cytometry as well as confocal microscopy. Surface marker expression was measured by flow cytometry. Toll-like receptor (TLR) expression patterns as well as cytokine expression upon TLR4 or TLR9 stimulation were assessed by real time RT-PCR and cytokine protein production was measured using a fluorescent bead-based immunoassay. Results IM were found to be smaller and morphologically more heterogeneous than AM, whereas phagocytic activity was similar in both cell types. HLA-DR expression was markedly higher in IM compared to AM. Although analysis of TLR expression profiles revealed no differences between the two cell populations, AM and IM clearly varied in cell reaction upon activation. Both MΦ populations were markedly activated by LPS as well as DNA isolated from attenuated mycobacterial strains (M. bovis H37Ra and BCG). Whereas AM expressed higher amounts of inflammatory cytokines upon activation, IM were more efficient in producing immunoregulatory cytokines, such as IL10, IL1ra, and IL6. Conclusion AM appear to be more effective as a non-specific first line of defence against inhaled pathogens, whereas IM show a more pronounced regulatory function. These dissimilarities should be taken into consideration in future studies on the role of human lung MΦ in the inflammatory response.
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Constantoulakis P, Filiou E, Rovina N, Chras G, Hamhougia A, Karabela S, Sotiriou A, Roussos C, Poulakis N. In vivo expression of innate immunity markers in patients with Mycobacterium tuberculosis infection. BMC Infect Dis 2010; 10:243. [PMID: 20718957 PMCID: PMC2931512 DOI: 10.1186/1471-2334-10-243] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2010] [Accepted: 08/18/2010] [Indexed: 01/04/2023] Open
Abstract
Background Toll-like receptors (TLRs), Coronin-1 and Sp110 are essential factors for the containment of Mycobacterium tuberculosis infection. The purpose of this study was to investigate the in vivo expression of these molecules at different stages of the infection and uncover possible relationships between these markers and the state of the disease. Methods Twenty-two patients with active tuberculosis, 15 close contacts of subjects with latent disease, 17 close contacts of subjects negative for mycobacterium antigens and 10 healthy, unrelated to patients, subjects were studied. Quantitative mRNA expression of Coronin-1, Sp110, TLRs-1,-2,-4 and -6 was analysed in total blood cells vs an endogenous house-keeping gene. Results The mRNA expression of Coronin-1, Sp110 and TLR-2 was significantly higher in patients with active tuberculosis and subjects with latent disease compared to the uninfected ones. Positive linear correlation for the expression of those factors was only found in the infected populations. Conclusions Our results suggest that the up-regulation of Coronin-1 and Sp110, through a pathway that also includes TLR-2 up-regulation may be involved in the process of tuberculous infection in humans. However, further studies are needed, in order to elucidate whether the selective upregulation of these factors in the infected patients could serve as a specific molecular marker of tuberculosis.
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17
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Oyama Y, Hashiguchi T, Taniguchi N, Tancharoen S, Uchimura T, Biswas KK, Kawahara KI, Nitanda T, Umekita Y, Lotz M, Maruyama I. High-mobility group box-1 protein promotes granulomatous nephritis in adenine-induced nephropathy. J Transl Med 2010; 90:853-66. [PMID: 20231821 PMCID: PMC3096665 DOI: 10.1038/labinvest.2010.64] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Granulomatous nephritis can be triggered by diverse factors and results in kidney failure. However, despite accumulating data about granulomatous inflammation, pathogenetic mechanisms in nephritis remain unclear. The DNA-binding high-mobility group box-1 protein (HMGB1) initiates and propagates inflammation when released by activated macrophages, and functions as an 'alarm cytokine' signaling tissue damage. In this study, we showed elevated HMGB1 expression in renal granulomas in rats with crystal-induced granulomatous nephritis caused by feeding an adenine-rich diet. HMGB1 levels were also raised in urine and serum, as well as in monocyte chemoattractant protein-1 (MCP-1), a mediator of granulomatous inflammation. Injection of HMGB1 worsened renal function and upregulated MCP-1 in rats with crystal-induced granulomatous nephritis. HMGB1 also induced MCP-1 secretion through mitogen-activated protein kinase (MAPK) and phosphoinositide-3-kinase (PI3K) pathways in rat renal tubular epithelial cells in vitro. Hmgb1(+/-) mice with crystal-induced nephritis displayed reduced MCP-1 expression in the kidneys and in urine and the number of macrophages in the kidneys was significantly decreased. We conclude that HMGB1 is a new mediator involved in crystal-induced nephritis that amplifies granulomatous inflammation in a cycle where MCP-1 attracts activated macrophages, resulting in excessive and sustained HMGB1 release. HMGB1 could be a novel target for inhibiting chronic granulomatous diseases.
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Affiliation(s)
- Yoko Oyama
- Department of Laboratory and Vascular Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Teruto Hashiguchi
- Department of Laboratory and Vascular Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Noboru Taniguchi
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California
| | - Salunya Tancharoen
- Pharmacology Department, Faculty of Dentistry, Mahidol University, Bangkok, Thailand
| | - Tomonori Uchimura
- Department of Laboratory and Vascular Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Kamal K. Biswas
- Department of Laboratory and Vascular Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Ko-ichi Kawahara
- Department of Laboratory and Vascular Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Takao Nitanda
- Division of Surgical Pathology, Kagoshima University Hospital, Kagoshima, Japan
| | - Yoshihisa Umekita
- Department of Tumor Pathology, Field of Oncology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Martin Lotz
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California
| | - Ikuro Maruyama
- Department of Laboratory and Vascular Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
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18
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Juarez E, Nuñez C, Sada E, Ellner JJ, Schwander SK, Torres M. Differential expression of Toll-like receptors on human alveolar macrophages and autologous peripheral monocytes. Respir Res 2010; 11:2. [PMID: 20051129 PMCID: PMC2817655 DOI: 10.1186/1465-9921-11-2] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2009] [Accepted: 01/05/2010] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Toll-like receptors (TLRs) are critical components in the regulation of pulmonary immune responses and the recognition of respiratory pathogens such as Mycobacterium Tuberculosis (M.tb). Through examination of human alveolar macrophages this study attempts to better define the expression profiles of TLR2, TLR4 and TLR9 in the human lung compartment which are as yet still poorly defined. METHODS Sixteen healthy subjects underwent venipuncture, and eleven subjects underwent additional bronchoalveolar lavage to obtain peripheral blood mononuclear and bronchoalveolar cells, respectively. Surface and intracellular expression of TLRs was assessed by fluorescence-activated cell sorting and qRT-PCR. Cells were stimulated with TLR-specific ligands and cytokine production assessed by ELISA and cytokine bead array. RESULTS Surface expression of TLR2 was significantly lower on alveolar macrophages than on blood monocytes (1.2 +/- 0.4% vs. 57 +/- 11.1%, relative mean fluorescence intensity [rMFI]: 0.9 +/- 0.1 vs. 3.2 +/- 0.1, p < 0.05). The proportion of TLR4 and TLR9-expressing cells and the rMFIs of TLR4 were comparable between alveolar macrophages and monocytes. The surface expression of TLR9 however, was higher on alveolar macrophages than on monocytes (rMFI, 218.4 +/- 187.3 vs. 4.4 +/- 1.4, p < 0.05) while the intracellular expression of the receptor and the proportion of TLR9 positive cells were similar in both cell types. TLR2, TLR4 and TLR9 mRNA expression was lower in bronchoalveolar cells than in monocytes.Pam3Cys, LPS, and M.tb DNA upregulated TLR2, TLR4 and TLR9 mRNA in both, bronchoalveolar cells and monocytes. Corresponding with the reduced surface and mRNA expression of TLR2, Pam3Cys induced lower production of TNF-alpha, IL-1beta and IL-6 in bronchoalveolar cells than in monocytes. Despite comparable expression of TLR4 on both cell types, LPS induced higher levels of IL-10 in monocytes than in alveolar macrophages. M.tb DNA, the ligand for TLR9, induced similar levels of cytokines in both cell types. CONCLUSION The TLR expression profile of autologous human alveolar macrophages and monocytes is not identical, therefore perhaps contributing to compartmentalized immune responses in the lungs and systemically. These dissimilarities may have important implications for the design and efficacy evaluation of vaccines with TLR-stimulating adjuvants that target the respiratory tract.
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Affiliation(s)
- Esmeralda Juarez
- Departamento de Microbiología, Instituto Nacional de Enfermedades Respiratorias, (Calzada de Tlalpan) México City, (14080), México
| | - Carlos Nuñez
- Servicio de Broncoscopia, Instituto Nacional de Enfermedades Respiratorias, (Calzada de Tlalpan) México City, (14080), México
| | - Eduardo Sada
- Departamento de Microbiología, Instituto Nacional de Enfermedades Respiratorias, (Calzada de Tlalpan) México City, (14080), México
| | - Jerrold J Ellner
- Center for Emerging & Reemerging Pathogens, University of Medicine and Dentistry New Jersey, (S Orange Ave), Newark, (07103), USA
- Department of Medicine, Section of Infectious Diseases, Boston Medical Center (Albany Street), Boston, (02118), USA
| | - Stephan K Schwander
- Center for Emerging & Reemerging Pathogens, University of Medicine and Dentistry New Jersey, (S Orange Ave), Newark, (07103), USA
- Department of Environmental and Occupational Health, University of Medicine and Dentistry New Jersey - School of Public Health (Hoes Lane) Piscataway, (08854), USA
- Center for Global Public Health, University of Medicine and Dentistry New Jersey - School of Public Health (Hoes Lane) Piscataway, (08854), USA
| | - Martha Torres
- Departamento de Microbiología, Instituto Nacional de Enfermedades Respiratorias, (Calzada de Tlalpan) México City, (14080), México
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Ito T, Schaller M, Raymond T, Joshi AD, Coelho AL, Frantz FG, Carson WF, Hogaboam CM, Lukacs NW, Standiford TJ, Phan SH, Chensue SW, Kunkel SL. Toll-like receptor 9 activation is a key mechanism for the maintenance of chronic lung inflammation. Am J Respir Crit Care Med 2009; 180:1227-38. [PMID: 19797157 DOI: 10.1164/rccm.200906-0892oc] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
RATIONALE Accumulating evidence supports the hypothesis that the continuous host response to a persistent challenge can polarize the cytokine environment toward a Th2 cytokine phenotype, but the mechanisms responsible for this skewing are not clear. OBJECTIVES We investigated the role of Toll-like receptor 9 (TLR9) in a Th2-driven pulmonary granulomatous response initiated via the embolization of Schistosoma mansoni eggs to the lungs of mice. METHODS Mice were intravenously injected with S. mansoni eggs. Histological and flow cytometric analysis, cytokine measurement, adoptive transfer of bone marrow (BM)-derived dendritic cells (DCs), and in vitro T-cell treatments with antigen-presenting cells were examined. MEASUREMENTS AND MAIN RESULTS In comparison to wild-type mice, TLR9(-/-) mice showed increased pulmonary granuloma size, augmented collagen deposition, increased Th2 cytokine phenotype, and impaired accumulation of DCs. BM-derived DCs, but not macrophages, recovered from animals with developed Th2-type lung granulomas promoted the production of type 2 cytokines from CD4(+) T cells. BM-derived DCs from TLR9(-/-) mice induced impaired Th1 cytokine and enhanced Th2 cytokine production by T cells, compared with DCs from WT mice. Macrophages from TLR9(-/-) mice expressed a significantly higher alternatively activated (M2) phenotype characterized by increased "found in inflammatory zone-1" (FIZZ1) and arginase-1 expression. The adoptive transfer of BM-derived DCs from syngeneic WT mice into TLR9(-/-) mice restored the granuloma phenotype seen in WT mice. CONCLUSIONS These studies suggest that TLR9 plays an important mechanistic role in the maintenance of the pulmonary granulomatous response.
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Affiliation(s)
- Toshihiro Ito
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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Meneghin A, Choi ES, Evanoff HL, Kunkel SL, Martinez FJ, Flaherty KR, Toews GB, Hogaboam CM. TLR9 is expressed in idiopathic interstitial pneumonia and its activation promotes in vitro myofibroblast differentiation. Histochem Cell Biol 2008; 130:979-92. [PMID: 18633634 DOI: 10.1007/s00418-008-0466-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2008] [Indexed: 12/28/2022]
Abstract
Infectious diseases can be cofactors in idiopathic interstitial pneumonias (IIP) pathogenesis; recent data suggests that toll-like receptors 9 (TLR9) ligands contribute to experimental chronic tissue remodeling. Real-time TAQMAN and immunohistochemical analysis of IIP normal surgical lung biopsies (SLBs), primary fibroblast lines grown from both IIP and normal SLBs indicate that TLR9 is prominently and differentially expressed in a disease-specific manner. TLR9 expression was increased in biopsies from patients with IIP compared with normal lung biopsies and its expression is localized to areas of marked interstitial fibrosis. TLR9 in fibroblasts appeared to be increased by profibrotic Th2 cytokines (IL-4 and IL-13) and this was true in fibroblasts cultured from the most severe form of IIP, idiopathic pulmonary fibrosis (IPF) SLBs, in non-specific interstitial pneumonia fibroblast lines, and in normal fibroblasts. Finally, confocal microscopy studies have shown that TLR9 activation by its synthetic agonist CpG-ODN significantly increased the expression of alpha smooth muscle actin, the main marker of myofibroblast differentiation. These data indicate that TLR9 expression may drive the abnormal tissue healing response in severe forms of IIP and its activation can have a key role in myofibroblast differentiation promoting the progression of disease during the terminal phase of IPF.
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Affiliation(s)
- A Meneghin
- Department of Pathology, University of Michigan Medical School, Room 4710, BSRB, 109 Zina Pitcher Pl, Ann Arbor, MI 48109-2200, USA.
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21
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Kiemer AK, Senaratne RH, Hoppstädter J, Diesel B, Riley LW, Tabeta K, Bauer S, Beutler B, Zuraw BL. Attenuated activation of macrophage TLR9 by DNA from virulent mycobacteria. J Innate Immun 2008; 1:29-45. [PMID: 20375564 DOI: 10.1159/000142731] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Accepted: 04/23/2008] [Indexed: 12/29/2022] Open
Abstract
Alveolar macrophages are the first line of host defence against mycobacteria, but an insufficient host response allows survival of bacteria within macrophages. We aimed to investigate the role of Toll-like receptor 9 (TLR9) activation in macrophage defence against mycobacteria. Human in vitro differentiated macrophages as well as human and mouse alveolar macrophages showed TLR9 mRNA and protein expression. The cells were markedly activated by DNA isolated from attenuated mycobacterial strains (H37Ra and Mycobacterium bovis BCG) as assessed by measuring cytokine expression by real-time PCR, whereas synthetic phosphorothioate-modified oligonucleotides had a much lower potency to activate human macrophages. Intracellular replication of H37Ra was higher in macrophages isolated from TLR9-deficient mice than in macrophages from wild-type mice, whereas H37Rv showed equal survival in cells from wild-type or mutant mice. Increased bacterial survival in mouse macrophages was accompanied by altered cytokine production as determined by Luminex bead assays. In vivo infection experiments also showed differential cytokine production in TLR9-deficient mice compared to wild-type animals. Both human monocyte-derived macrophages as well as human alveolar macrophages showed reduced activation upon treatment with DNA isolated from bacteria from virulent (M. bovis and H37Rv) compared to attenuated mycobacteria. We suggest attenuated TLR9 activation contributes to the insufficient host response against virulent mycobacteria.
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Prabha C, Rajashree P, Sulochana DD. TLR2 and TLR4 expression on the immune cells of tuberculous pleural fluid. Immunol Lett 2007; 117:26-34. [PMID: 18295348 DOI: 10.1016/j.imlet.2007.11.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 11/01/2007] [Accepted: 11/04/2007] [Indexed: 12/12/2022]
Abstract
Toll-like receptors (TLRs) play an important role in mediating the down stream signaling of immune response in tuberculosis. The predominance of Th1 response in tuberculous pleurisy prompted us to study the expression profiles of TLR2 and TLR4 on different immune cells and on subsets of T cells obtained from the site of infection. Our results showed that TLR2 was up-regulated on the monocytes from pleural fluid indicating a prominent role for this receptor in anti-tuberculous immunity. Notably, TLR2 and TLR4 expression were also enhanced on IFN-gamma secreting CD4(+)T cells. However, their expression was down-regulated on activated and IL-4 secreting CD4(+)T cells from the site of infection indicating that TLR expression is differentially modulated on the different subsets of T cells depending on their activation status and cytokine expression. The down-regulation of both TLRs on the natural regulatory T cells despite their higher number at the site of infection might be a mechanism to maintain their suppressive activity.
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Affiliation(s)
- C Prabha
- Department of Immunology, Tuberculosis Research Centre (ICMR), Mayor V.R. Ramanathan Road, Chetput, Chennai 600031, India
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Mueller T, Terada T, Rosenberg IM, Shibolet O, Podolsky DK. Th2 Cytokines Down-Regulate TLR Expression and Function in Human Intestinal Epithelial Cells. THE JOURNAL OF IMMUNOLOGY 2006; 176:5805-14. [PMID: 16670286 DOI: 10.4049/jimmunol.176.10.5805] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TLRs serve important immune and nonimmune functions in human intestinal epithelial cells (IECs). Proinflammatory Th1 cytokines have been shown to promote TLR expression and function in IECs, but the effect of key Th2 cytokines (IL-4, IL-5, IL-13) on TLR signaling in IECs has not been elucidated so far. We stimulated human model IECs with Th2 cytokines and examined TLR mRNA and protein expression by Northern blotting, RT-PCR, real-time RT-PCR, Western blotting, and flow cytometry. TLR function was determined by I-kappaBalpha phosphorylation assays, ELISA for IL-8 secretion after stimulation with TLR ligands and flow cytometry for LPS uptake. IL-4 and IL-13 significantly decreased TLR3 and TLR4 mRNA and protein expression including the requisite TLR4 coreceptor MD-2. TLR4/MD-2-mediated LPS uptake and TLR ligand-induced I-kappaBalpha phosphorylation and IL-8 secretion were significantly diminished in Th2 cytokine-primed IECs. The down-regulatory effect of Th2 cytokines on TLR expression and function in IECs also counteracted enhanced TLR signaling induced by stimulation with the hallmark Th1 cytokine IFN-gamma. In summary, Th2 cytokines appear to dampen TLR expression and function in resting and Th1 cytokine-primed human IECs. Diminished TLR function in IECs under the influence of Th2 cytokines may protect the host from excessive TLR signaling, but likely also impairs the host intestinal innate immune defense and increases IEC susceptibility to chronic inflammation in response to the intestinal microenvironment. Taken together, our data underscore the important role of Th2 cytokines in balancing TLR signaling in human IECs.
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Affiliation(s)
- Tobias Mueller
- Gastrointestinal Unit, Department of Medicine, Center for the Study of Inflammatory Bowel Disease, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA
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Chang JS, Huggett JF, Dheda K, Kim LU, Zumla A, Rook GAW. Myobacterium tuberculosis induces selective up-regulation of TLRs in the mononuclear leukocytes of patients with active pulmonary tuberculosis. THE JOURNAL OF IMMUNOLOGY 2006; 176:3010-8. [PMID: 16493059 DOI: 10.4049/jimmunol.176.5.3010] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Human and mouse studies indicate that TLRs are important in mycobacterial infections. We investigated TLR gene expression in fresh unstimulated blood and bronchoalveolar lavage from patients with pulmonary tuberculosis using a well-validated, real-time PCR. A human splice variant of TLR1, designated hsTLR1, was found in all donors tested. hsTLR1 mRNA lacks exon 2, which is a 77-bp region of the 5'-untranslated region, but contains the same coding sequence as TLR1. Compared with the matched controls, whole blood from patients had increased levels of mRNA encoding TLR2 (p = 0.0006), TLR1 (p = 0.004), hsTLR1 (p = 0.0003), TLR6 (p < 0.0001), and TLR4 (p = 0.0002). By contrast, expression of these TLRs was not increased in bronchoalveolar lavage. An increased level of hsTLR1 mRNA was found in both CD3- (p = 0.0078) and CD4+ cells (p = 0.028), resulting in an increased ratio of hsTLR1 mRNA to TLR1 and to TLR6 mRNA. An in vitro study in THP1 cells suggested that this relative increase in hsTLR1 might be attributable to a direct effect of mycobacterial components because it could be mimicked by mycobacterial preparations in the absence of IFN-gamma or T cells and by the TLR1/2 agonist Pam3CysK4. Half-life studies using blood from patients with pulmonary tuberculosis and THP1 cells exposed to Myobacterium tuberculosis in vitro showed p38 MAPK-independent stabilization of mRNAs encoding hsTLR1 and TLR1. We conclude that M. tuberculosis exerts direct effects on patterns of TLR expression, partly via changes in mRNA half-life. The significance of these changes in the pathogenesis of disease deserves further investigation.
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Affiliation(s)
- Jung-Su Chang
- Centre for Infectious Diseases and International Health, Royal Free and University College Medical School, London, United Kingdom
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Demedts IK, Bracke KR, Maes T, Joos GF, Brusselle GG. Different roles for human lung dendritic cell subsets in pulmonary immune defense mechanisms. Am J Respir Cell Mol Biol 2006; 35:387-93. [PMID: 16627825 DOI: 10.1165/rcmb.2005-0382oc] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Dendritic cells (DC) have a central role in the initiation of adequate immune responses. They recognize pathogens by means of Toll-like receptors (TLR) and link innate to adaptive immune responses by releasing proinflammatory cytokines and inducing T cell proliferation. We conducted this study to evaluate the expression and function of TLR on human lung DC subsets and to study their T cell stimulatory capacity. TLR gene expression by human pulmonary DC was evaluated by RT-PCR, while protein expression was analyzed by flow cytometry. We investigated cytokine release by DC in response to different TLR ligands. T cell stimulatory capacity was evaluated by mixed leukocyte reactions of purified lung DC with allogeneic T cells. Myeloid dendritic cells type 1 (mDC1) and myeloid dendritic cells type 2 (mDC2) express mRNA transcripts for TLR1, TLR2, TLR3, TLR4, TLR6, and TLR8. Flow cytometric analysis demonstrated high TLR2 protein expression for mDC1 and moderate TLR4 expression for mDC2. mDC1 and mDC2 release proinflammatory cytokines (TNF-alpha, IL-1beta, IL-6, and IL-8) in response to TLR2 and TLR4 ligands. TLR3 ligands induce cytokine release in mDC1, but not in mDC2. Plasmacytoid DC (pDC) express TLR7 and TLR9 and release proinflammatory cytokines in response to imiquimod and IFN-alpha in response to CpG oligonucleotides. mDC1 are strong inducers of T cell proliferation, while pDC hardly induce any T cell proliferation. mDC2 have an intermediate T cell-stimulatory capacity. Our results show divergent roles for the different human lung DC subsets, both in innate and adaptive immune responses.
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Affiliation(s)
- Ingel K Demedts
- Department of Respiratory Diseases, Ghent University Hospital 7K12IE, De Pintelaan 185, B-9000 Ghent, Belgium.
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Shan X, Hu A, Veler H, Fatma S, Grunstein JS, Chuang S, Grunstein MM. Regulation of Toll-like receptor 4-induced proasthmatic changes in airway smooth muscle function by opposing actions of ERK1/2 and p38 MAPK signaling. Am J Physiol Lung Cell Mol Physiol 2006; 291:L324-33. [PMID: 16581829 DOI: 10.1152/ajplung.00056.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Activation of Toll-like receptors (TLRs) on immune surveillance cells in the lung has been implicated in the pathobiology of allergic asthma, a condition associated with altered airway smooth muscle (ASM) contractility. Because ASM is known to directly respond to various proasthmatic stimuli, the potential role of TLR signaling in ASM in regulating airway expression of the proasthmatic phenotype was investigated. Cultured human ASM cells were found to express TLR4 and TLR9 mRNA transcripts and, whereas TLR9 stimulation had little effect, TLR4 activation with LPS elicited significant increases in IL-6 release and evoked proasthmatic-like changes in the constrictor and relaxation responsiveness of isolated rabbit ASM tissues. Complementary studies further demonstrated that the ASM responses to LPS were associated with activation of the ERK1/2 and p38 MAPK signaling pathways, IKK-mediated activation of NF-kappaB, and coupling of phosphorylated ERK1/2 with the p65 subunit of NF-kappaB. Moreover, the induced NF-kappaB activity and changes in ASM responsiveness were prevented in LPS-exposed ASM that were pretreated with inhibitors of ERK1/2 signaling, whereas inhibition of p38 MAPK augmented the proasthmatic responses to LPS. Finally, activation of p38 MAPK with anisomycin prevented both the LPS-induced stimulation of ERK1/2-mediated NF-kappaB activity and associated changes in ASM responsiveness. Collectively, these data support the novel concept that TLR4 activation in ASM elicits changes in ASM function that are regulated by opposing effects of MAPK signaling, wherein LPS-induced ERK1/2 activation mediates NF-kappaB-dependent proasthmatic-like changes in ASM function, whereas coactivation of p38 MAPK serves to homeostatically downregulate the proasthmatic effects of ERK1/2 activation.
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Affiliation(s)
- Xiaoyin Shan
- The Joseph Stokes Jr. Research Institute, Division of Pulmonary Medicine, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Pennsylvania, USA
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27
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Hewson CA, Jardine A, Edwards MR, Laza-Stanca V, Johnston SL. Toll-like receptor 3 is induced by and mediates antiviral activity against rhinovirus infection of human bronchial epithelial cells. J Virol 2005; 79:12273-9. [PMID: 16160153 PMCID: PMC1211516 DOI: 10.1128/jvi.79.19.12273-12279.2005] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Rhinoviruses (RV) are the major cause of the common cold and acute exacerbations of asthma and chronic obstructive pulmonary disease. Toll-like receptors (TLRs) are a conserved family of receptors that recognize and respond to a variety of pathogen-associated molecular patterns. TLR3 recognizes double-stranded RNA, an important intermediate of many viral life cycles (including RV). The importance of TLR3 in host responses to virus infection is not known. Using BEAS-2B (a human bronchial epithelial cell-line), we demonstrated that RV replication increased the expression of TLR3 mRNA and TLR3 protein on the cell surface. We observed that blocking TLR3 led to a decrease in interleukin-6, CXCL8, and CCL5 in response to poly(IC) but an increase following RV infection. Finally, we demonstrated that TLR3 mediated the antiviral response. This study demonstrates an important functional requirement for TLR3 in the host response against live virus infection and indicates that poly(IC) is not always a good model for studying the biology of live virus infection.
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Affiliation(s)
- Christopher A Hewson
- Department of Respiratory Medicine, National Heart and Lung Institute and Wright Fleming Institute of Infection and Immunity, Imperial College London, Norfolk Place, London W2 1PG, United Kingdom
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28
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Mariotti S, Teloni R, Iona E, Fattorini L, Romagnoli G, Gagliardi MC, Orefici G, Nisini R. Mycobacterium tuberculosis diverts alpha interferon-induced monocyte differentiation from dendritic cells into immunoprivileged macrophage-like host cells. Infect Immun 2004; 72:4385-92. [PMID: 15271894 PMCID: PMC470689 DOI: 10.1128/iai.72.8.4385-4392.2004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dendritic cells (DCs) are critical for initiating a pathogen-specific T-cell response. During chronic infections the pool of tissue DCs must be renewed by recruitment of both circulating DC progenitors and in loco differentiating monocytes. However, the interaction of monocytes with pathogens could affect their differentiation. Mycobacterium tuberculosis has been shown to variably interfere with the generation and function of antigen-presenting cells (APCs). In this study we found that when alpha interferon (IFN-alpha) is used as an inductor of monocyte differentiation, M. tuberculosis inhibits the generation of DCs, forcing the generation of immunoprivileged macrophage-like cells instead. Cells derived from M. tuberculosis-infected monocyte-derived macrophages (M. tuberculosis-infected MoMphi) retained CD14 without acquiring CD1 molecules and partially expressed B7.2 but did not up-regulate B7.1 and major histocompatibility complex (MHC) class I and II molecules. They synthesized tumor necrosis factor alpha and interleukin-10 (IL-10) but not IL-12. They also showed a reduced ability to induce proliferation and functional polarization of allogeneic T lymphocytes. Thus, in the presence of IFN-alpha, M. tuberculosis may hamper the renewal of potent APCs, such as DCs, generating a safe habitat for intracellular growth. M. tuberculosis-infected MoMphi, in fact, showed reduced expression of both signal 1 (CD1, MHC classes I and II) and signal 2 (B7.1 and B7.2), which are essential for mycobacterium-specific T-lymphocyte priming and/or activation. These data further suggest that M. tuberculosis has the ability to specifically interfere with monocyte differentiation. This ability may represent an effective M. tuberculosis strategy for eluding immune surveillance and persisting in the host.
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Affiliation(s)
- Sabrina Mariotti
- Dipartimento di Malattie Infettive, Parassitarie e Immunomediate, Istituto Superiore di Sanitá, Viale Regina Elena 299, 00161 Rome, Italy
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Basu S, Fenton MJ. Toll-like receptors: function and roles in lung disease. Am J Physiol Lung Cell Mol Physiol 2004; 286:L887-92. [PMID: 15064235 DOI: 10.1152/ajplung.00323.2003] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Toll-like receptor (TLR) proteins have been shown to play a pivotal role in both innate and adaptive immune responses in higher vertebrates. TLR proteins enable the host to recognize a large number of pathogen-associated molecular patterns such as bacterial lipopolysaccharides, viral RNA, CpG-containing DNA, and flagellin, among others. Engagement of TLR proteins leads to the upregulation of costimulatory molecules and proinflammatory cytokines, as well as reactive nitrogen and oxygen products. The role of TLR proteins in lung-associated pathologies such as airway hyperreactivity, allergic asthma, and tuberculosis is being intensively studied. This review summarizes many of the findings made to date on the roles of TLR proteins in a variety of lung diseases. Generally, TLR proteins serve a protective role in infectious diseases, such as tuberculosis. The progression of chronic inflammatory lung diseases, such as allergic asthma, can also be influenced by TLR-dependent responses.
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Affiliation(s)
- Subhendu Basu
- Division of Pulmonary and Critical Care Medicine, Univ. of Maryland School of Medicine, 685 W. Baltimore St., MSTF-800, Baltimore, MD 21201-1192, USA.
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Uronen-Hansson H, Allen J, Osman M, Squires G, Klein N, Callard RE. Toll-like receptor 2 (TLR2) and TLR4 are present inside human dendritic cells, associated with microtubules and the Golgi apparatus but are not detectable on the cell surface: integrity of microtubules is required for interleukin-12 production in response to internalized bacteria. Immunology 2004; 111:173-8. [PMID: 15027902 PMCID: PMC1782406 DOI: 10.1111/j.0019-2805.2003.01803.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The activation of dendritic cells (DCs) by microbes is mediated by pattern recognition receptors including the Toll-like receptors (TLR). Bacterial lipopolysaccharide acts via TLR4 whereas peptidoglycan and lipoprotein responses are mediated by TLR2. It is generally accepted that TLR binding to microbes occurs at the cell surface but this has not been directly demonstrated for human DCs. We show here that TLR2 and TLR4 are expressed inside DCs in an abundant tubulovesicular pattern with a focus of intense staining adjacent to the nucleus. In contrast, there was no detectable expression on the cell surface. TLR2 and TLR4 were readily found both intracellularly and on the surface of monocytes. They were shown to be closely associated with the Golgi complex and colocalized with alpha-tubulin, displaying a high focal concentration at the microtubule organizing centre. Alignment of TLR2 and TLR4 with microtubules was observed, suggesting that microtubules serve as transport tracks for TLR vesicles. Depolymerization of the microtubule network disrupted the intracellular expression of TLR2 and TLR4 and profoundly inhibited interleukin-12 (IL-12) production in response to Neisseria meningitidis but did not prevent phagocytosis. These data are consistent with the bacterial signalling through TLR2 and TLR4 required for IL-12 production occurring inside DCs after phagocytosis.
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