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Ikeogu N, Olayinka-Adefemi F, Edechi C, Onyilagha C, Jia P, Marshall A, Ode J, Uzonna J. Crosspteryx fibrifuga leaf extract enhances host resistance to Trypanosoma congolense infection in mice by regulating host immune response and disrupting the activity of parasite superoxide dismutase enzyme. Front Microbiol 2023; 14:1275365. [PMID: 37954253 PMCID: PMC10635443 DOI: 10.3389/fmicb.2023.1275365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 10/13/2023] [Indexed: 11/14/2023] Open
Abstract
African trypanosomiasis, a neglected tropical disease, is caused by diverse species of the protozoan parasite belonging to the genus Trypanosoma. Although anti-trypanosomal medications exist, the increase in drug resistance and persistent antigenic variation has necessitated the development of newer and more efficacious therapeutic agents which are selectively toxic to the parasite. In this study, we assessed the trypanocidal efficacy of Crosspteryx fibrifuga leaf extract (C.f/L-extract) in vitro. Following treatment of T. congolense parasites with C.f/L-extract, we observed a significant decrease in parasite number and an elevation in the expression of the apoptotic markers, Annexin V and 7-Aminoactinomycin D (7AAD). Interestingly, at the same concentration (50 μg/mL), C.f/L-extract was not cytotoxic to murine whole splenocytes. We also observed a significant increase in pro-inflammatory cytokines and nitric oxide secretion by bone marrow derived macrophages following treatment with C.f/L-extract (10 μg/mL and 50 μg/mL) compared to PBS treated controls, suggesting that the extract possesses an immune regulatory effect. Treatment of T. congolense infected mice with C.f/L-extract led to significant decrease in parasite numbers and a modest increase in mouse survival compared to PBS treated controls. In addition, there was a significant increase in CD4+IFN-γ+ T cells and a decrease in CD4+IL-10+ T cells in the spleens of T. congolense infected mice treated with C.f/L-extract. Interestingly, C.f/L-extract treatment decreased the activity of superoxide dismutase (an enzyme that protects unicellular organisms from oxidative stress) in T. congolense parasites but not in splenocytes. Collectively, our study has identified C.f/L-extract as a potential anti-trypanosomal agent that warrant further investigation and possibly explored as a treatment option for T. congolense infection.
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Affiliation(s)
- Nnamdi Ikeogu
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
| | | | - Chidalu Edechi
- Department of Pathology, University of Manitoba, Winnipeg, MB, Canada
| | - Chukwunonso Onyilagha
- National Centre for Foreign Animal Disease, Canadian Food Inspection Agency, Winnipeg, MB, Canada
| | - Ping Jia
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
| | - Aaron Marshall
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
| | - Julius Ode
- Department of Veterinary Pharmacology and Toxicology, University of Abuja, Abuja, Nigeria
| | - Jude Uzonna
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
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Hui Z, Fu Y, Chen Y, Yin J, Fang H, Tu Y, Gu Y, Zhang J. Loss of TRIM24 promotes IL-10 expression via CBP/p300-dependent IFNβ1 transcription during macrophage activation. Inflamm Res 2023:10.1007/s00011-023-01751-x. [PMID: 37326695 DOI: 10.1007/s00011-023-01751-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/25/2023] [Accepted: 05/03/2023] [Indexed: 06/17/2023] Open
Abstract
BACKGROUND As an anti-inflammatory cytokine, interleukin 10 (IL-10) plays a vital role in preventing inflammatory and autoimmune pathologies while also maintaining immune homeostasis. IL-10 production in macrophages is tightly regulated by multiple pathways. TRIM24, a member of the Transcriptional Intermediary Factor 1 (TIF1) family, contributes to antiviral immunity and macrophage M2 polarization. However, the role of TRIM24 in regulating IL-10 expression and its involvement in endotoxic shock remains unclear. METHODS In vitro, bone marrow derived macrophages cultured with GM-CSF or M-CSF were stimulated with LPS (100ng/ml). Murine models of endotoxic shock were established by challenging the mice with different dose of LPS (i.p). RTPCR, RNA sequencing, ELISA and hematoxylin and eosin staining were performed to elucidate the role and mechanisms of TRIM24 in endotoxic shock. RESULTS The expression of TRIM24 is downregulated in LPS-stimulated bone marrow-derived macrophages (BMDMs). Loss of TRIM24 boosted IL-10 expression during the late stage of LPS-stimulation in macrophages. RNA-seq analysis revealed the upregulation of IFNβ1, an upstream regulator of IL-10, in TRIM24 knockout macrophages. Treatment with C646, a CBP/p300 inhibitor, diminished the difference in both IFNβ1 and IL-10 expression between TRIM24 knockout and control macrophages. Loss of TRIM24 provided protection against LPS-induced endotoxic shock in mice. CONCLUSION Our results demonstrated that inhibiting TRIM24 promoted the expression of IFNβ1 and IL-10 during macrophage activation, therefore protecting mice from endotoxic shock. This study offers novel insights into the regulatory role of TRIM24 in IL-10 expression, making it a potentially attractive therapeutic target for inflammatory diseases.
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Affiliation(s)
- Zhaoyuan Hui
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, Zhejiang, China
- Department of Pathogenic Biology and Medical Immunology, School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, 750004, China
- Department of Genetics, Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou, 310058, China
- Ningxia Key Laboratory of Prevention and Control of Common Infectious Diseases, Yinchuan, 750004, China
| | - Yuanzheng Fu
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, Zhejiang, China
- Department of Genetics, Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Yunyun Chen
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, Zhejiang, China
- Department of Genetics, Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Jie Yin
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, Zhejiang, China
- Department of Genetics, Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Hui Fang
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, Zhejiang, China
- Department of Genetics, Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Yifan Tu
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, Zhejiang, China
- Department of Genetics, Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Ying Gu
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, Zhejiang, China.
- Department of Genetics, Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
- Zhejiang Provincial Key Lab of Genetic and Developmental Disorder, Hangzhou, 310058, Zhejiang, China.
- Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, 311121, China.
| | - Jiawei Zhang
- Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, Zhejiang, China.
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3
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Nguyen HTT, Radwanska M, Magez S. Tipping the balance between erythroid cell differentiation and induction of anemia in response to the inflammatory pathology associated with chronic trypanosome infections. Front Immunol 2022; 13:1051647. [PMID: 36420267 PMCID: PMC9676970 DOI: 10.3389/fimmu.2022.1051647] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 10/19/2022] [Indexed: 11/09/2022] Open
Abstract
Infection caused by extracellular single-celled trypanosomes triggers a lethal chronic wasting disease in livestock and game animals. Through screening of 10 Trypanosoma evansi field isolates, exhibiting different levels of virulence in mice, the current study identifies an experimental disease model in which infection can last well over 100 days, mimicking the major features of chronic animal trypanosomosis. In this model, despite the well-controlled parasitemia, infection is hallmarked by severe trypanosomosis-associated pathology. An in-depth scRNA-seq analysis of the latter revealed the complexity of the spleen macrophage activation status, highlighting the crucial role of tissue resident macrophages (TRMs) in regulating splenic extramedullary erythropoiesis. These new data show that in the field of experimental trypanosomosis, macrophage activation profiles have so far been oversimplified into a bi-polar paradigm (M1 vs M2). Interestingly, TRMs exert a double-sided effect on erythroid cells. On one hand, these cells express an erythrophagocytosis associated signature. On another hand, TRMs show high levels of Vcam1 expression, known to support their interaction with hematopoietic stem and progenitor cells (HSPCs). During chronic infection, the latter exhibit upregulated expression of Klf1, E2f8, and Gfi1b genes, involved in erythroid differentiation and extramedullary erythropoiesis. This process gives rise to differentiation of stem cells to BFU-e/CFU-e, Pro E, and Baso E subpopulations. However, infection truncates progressing differentiation at the orthochromatic erythrocytes level, as demonstrated by scRNAseq and flow cytometry. As such, these cells are unable to pass to the reticulocyte stage, resulting in reduced number of mature circulating RBCs and the occurrence of chronic anemia. The physiological consequence of these events is the prolonged poor delivery of oxygen to various tissues, triggering lactic acid acidosis and the catabolic breakdown of muscle tissue, reminiscent of the wasting syndrome that is characteristic for the lethal stage of animal trypanosomosis.
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Affiliation(s)
- Hang Thi Thu Nguyen
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Magdalena Radwanska
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Stefan Magez
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
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Kumar R, Gupta S, Bhutia WD, Vaid RK, Kumar S. Atypical human trypanosomosis: Potentially emerging disease with lack of understanding. Zoonoses Public Health 2022; 69:259-276. [PMID: 35355422 DOI: 10.1111/zph.12945] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 03/21/2022] [Accepted: 03/21/2022] [Indexed: 02/03/2023]
Abstract
Trypanosomes are the hemoflagellate kinetoplastid protozoan parasites affecting a wide range of vertebrate hosts having insufficient host specificity. Climatic change, deforestation, globalization, trade agreements, close association and genetic selection in links with environmental, vector, reservoir and potential susceptible hosts' parameters have led to emergence of atypical human trypanosomosis (a-HT). Poor recording of such neglected tropical disease, low awareness in health professions and farming community has approached a serious intimidation for mankind. Reports of animal Trypanosoma species are now gradually increasing in humans, and lack of any compiled literature has diluted the issue. In the present review, global reports of livestock and rodent trypanosomes reported from human beings are assembled and discrepancies with the available literature are discussed along with morphological features of Trypanosoma species. We have described 21 human cases from the published information. Majority of cases 10 (47%) are due to T. lewisi, followed by 5 (24%) cases of T. evansi, 4 (19%) cases of T. brucei and 1 (5%) case each of T. vivax and T. congolense. Indian subcontinent witnessed 13 cases of a-HT, of which 9 cases are reported from India, which includes 7 cases of T. lewisi and 2 cases of T. evansi. Apart from, a-HT case reports, epidemiological investigation and treatment aspects are also discussed. An attempt has been made to provide an overview of the current situation of atypical human trypanosomosis caused by salivarian animal Trypanosoma globally. The probable role of Trypanosoma lytic factors (TLF) present in normal human serum (NHS) in providing innate immunity against salivarian animal Trypanosoma species and the existing paradox in medical science after the finding on intact functional apolipoprotein L1 (ApoL1) in Vietnam T. evansi Type A case is also discussed to provide an update on all aspects of a-HT. Insufficient data and poor reporting in Asian and African countries are the major hurdle resulting in under-reporting of a-HT, which is a potential emerging threat. Therefore, concerted efforts must be directed to address attentiveness, preparedness and regular surveillance in suspected areas with training of field technicians, medical health professionals and veterinarians. Enhancing a one health approach is specifically important in case of trypanosomosis.
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Affiliation(s)
- Rajender Kumar
- Parasitology Lab, ICAR-National Research Centre on Equines, Hisar, India
| | - Snehil Gupta
- Department of Veterinary Parasitology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, India
| | | | | | - Sanjay Kumar
- Parasitology Lab, ICAR-National Research Centre on Equines, Hisar, India
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5
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Chulanetra M, Chaicumpa W. Revisiting the Mechanisms of Immune Evasion Employed by Human Parasites. Front Cell Infect Microbiol 2021; 11:702125. [PMID: 34395313 PMCID: PMC8358743 DOI: 10.3389/fcimb.2021.702125] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/25/2021] [Indexed: 12/14/2022] Open
Abstract
For the establishment of a successful infection, i.e., long-term parasitism and a complete life cycle, parasites use various diverse mechanisms and factors, which they may be inherently bestowed with, or may acquire from the natural vector biting the host at the infection prelude, or may take over from the infecting host, to outmaneuver, evade, overcome, and/or suppress the host immunity, both innately and adaptively. This narrative review summarizes the up-to-date strategies exploited by a number of representative human parasites (protozoa and helminths) to counteract the target host immune defense. The revisited information should be useful for designing diagnostics and therapeutics as well as vaccines against the respective parasitic infections.
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Affiliation(s)
- Monrat Chulanetra
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Wanpen Chaicumpa
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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6
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Chen JY, Zhou JK, Pan W. Immunometabolism: Towards a Better Understanding the Mechanism of Parasitic Infection and Immunity. Front Immunol 2021; 12:661241. [PMID: 34122419 PMCID: PMC8191844 DOI: 10.3389/fimmu.2021.661241] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/13/2021] [Indexed: 12/26/2022] Open
Abstract
As a relatively successful pathogen, several parasites can establish long-term infection in host. This “harmonious symbiosis” status relies on the “precise” manipulation of host immunity and metabolism, however, the underlying mechanism is still largely elusive. Immunometabolism is an emerging crossed subject in recent years. It mainly discusses the regulatory mechanism of metabolic changes on reprogramming the key transcriptional and post-transcriptional events related to immune cell activation and effect, which provides a novel insight for understanding how parasites regulate the infection and immunity in hosts. The present study reviewed the current research progress on metabolic reprogramming mechanism exploited by parasites to modulate the function in various immune cells, highlighting the future exploitation of key metabolites or metabolic events to clarify the underlying mechanism of anti-parasite immunity and design novel intervention strategies against parasitic infection.
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Affiliation(s)
- Jing-Yue Chen
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,The First Clinical Medicine, Xuzhou Medical University, Xuzhou, China
| | - Ji-Kai Zhou
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China.,The First Clinical Medicine, Xuzhou Medical University, Xuzhou, China
| | - Wei Pan
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogen Biology and Immunology, Xuzhou Medical University, Xuzhou, China
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7
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The potential therapeutic effect of adipose-derived mesenchymal stem cells in the treatment of cutaneous leishmaniasis caused by L. major in BALB/c mice. Exp Parasitol 2021; 222:108063. [PMID: 33412170 DOI: 10.1016/j.exppara.2020.108063] [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: 08/21/2020] [Revised: 12/12/2020] [Accepted: 12/23/2020] [Indexed: 12/14/2022]
Abstract
Leishmaniasis is one of the most neglected tropical infectious diseases in the world. The emergence of drug resistance and toxicity and the high cost of the available drugs with a lack of new anti-leishmanial drugs highlight the need to search for newer therapies with anti-leishmanial activities. Due to the mesenchymal stem cell (MSC) immunomodulatory capacity, they have been applied in a wide variety of disorders. In this study, the potential effects of adipose-derived MSC (AD-MSCs) therapy and its combination with glucantime were evaluated in a murine model of cutaneous leishmaniasis induced by L. major. The results showed that AD-MSCs improved wound healing and decreased parasite burden. The real-time PCR results obtained from mice treated with AD-MSCs showed that IL-12 and TNF-α genes were upregulated. IL-10, arginase, and FOXP3 genes were downregulated whereas no differences in expression of the IL-4 gene were found. Overall, it seems that AD-MSCs therapy enhances Th1 immune response in L. major infected BALB/c mice. Unexpectedly, our results showed that the association of glucantime to AD-MSCs treatments did not lead to an increment in the anti-leishmanial activity.
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8
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Gobert AP, Finley JL, Latour YL, Asim M, Smith TM, Verriere TG, Barry DP, Allaman MM, Delagado AG, Rose KL, Calcutt MW, Schey KL, Sierra JC, Piazuelo MB, Mirmira RG, Wilson KT. Hypusination Orchestrates the Antimicrobial Response of Macrophages. Cell Rep 2020; 33:108510. [PMID: 33326776 PMCID: PMC7812972 DOI: 10.1016/j.celrep.2020.108510] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 10/28/2020] [Accepted: 11/18/2020] [Indexed: 12/21/2022] Open
Abstract
Innate responses of myeloid cells defend against pathogenic bacteria via inducible effectors. Deoxyhypusine synthase (DHPS) catalyzes the transfer of the N-moiety of spermidine to the lysine-50 residue of eukaryotic translation initiation factor 5A (EIF5A) to form the amino acid hypusine. Hypusinated EIF5A (EIF5AHyp) transports specific mRNAs to ribosomes for translation. We show that DHPS is induced in macrophages by two gastrointestinal pathogens, Helicobacter pylori and Citrobacter rodentium, resulting in enhanced hypusination of EIF5A. EIF5AHyp was also increased in gastric macrophages from patients with H. pylori gastritis. Furthermore, we identify the bacteria-induced immune effectors regulated by hypusination. This set of proteins includes essential constituents of antimicrobial response and autophagy. Mice with myeloid cell-specific deletion of Dhps exhibit reduced EIF5AHyp in macrophages and increased bacterial burden and inflammation. Thus, regulation of translation through hypusination is a critical hallmark of the defense of eukaryotic hosts against pathogenic bacteria. Gobert et al. demonstrate that hypusination, a specific mechanism regulating translation, is induced in macrophages by bacteria. Hypusination is required for the translation of inducible antimicrobial effectors. Mice that specifically lack hypusination in macrophages are highly susceptible to Helicobacter pylori and Citrobacter rodentium, two pathogens of the gastrointestinal tract.
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Affiliation(s)
- Alain P Gobert
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
| | - Jordan L Finley
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Yvonne L Latour
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Mohammad Asim
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Thaddeus M Smith
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Thomas G Verriere
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Daniel P Barry
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Margaret M Allaman
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Alberto G Delagado
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kristie L Rose
- Department of Biochemistry, Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - M Wade Calcutt
- Department of Biochemistry, Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Kevin L Schey
- Department of Biochemistry, Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Johanna C Sierra
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - M Blanca Piazuelo
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Raghavendra G Mirmira
- Translational Research Center, Department of Medicine, The University of Chicago, Chicago, IL 60637, USA
| | - Keith T Wilson
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37232, USA.
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9
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Haydar D, Gonzalez R, Garvy BA, Garneau-Tsodikova S, Thamban Chandrika N, Bocklage TJ, Feola DJ. Myeloid arginase-1 controls excessive inflammation and modulates T cell responses in Pseudomonas aeruginosa pneumonia. Immunobiology 2020; 226:152034. [PMID: 33278710 DOI: 10.1016/j.imbio.2020.152034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/20/2020] [Accepted: 10/18/2020] [Indexed: 12/24/2022]
Abstract
Regulatory properties of macrophages associated with alternative activation serve to limit the exaggerated inflammatory response during pneumonia caused by Pseudomonas aeruginosa infection. Arginase-1 is an important effector of these macrophages believed to play an essential role in decreasing injury and promoting repair. We investigated the role of arginase-1 in the control of inflammatory immune responses to P. aeruginosa pneumonia in mice that exhibit different immunologic phenotypes. C57BL/6 mice with conditional knockout of the arginase-1 (Arg1) gene from myeloid cells (Arg1ΔM) or BALB/c mice treated with small molecule inhibitors of arginase were infected intratracheally with P. aeruginosa. Weight loss, mortality, bacterial clearance, and lung injury were assessed and compared, as were the characterization of immune cell populations over time post-infection. Myeloid arginase-1 deletion resulted in greater morbidity along with more severe inflammatory responses compared to littermate control mice. Arg1ΔM mice had greater numbers of neutrophils, macrophages, and lymphocytes in their airways and lymph nodes compared to littermate controls. Additionally, Arg1ΔM mice recovered from inflammatory lung injury at a significantly slower rate. Conversely, treatment of BALB/c mice with the arginase inhibitor S-(2-boronoethyl)-l-cysteine hydrochloride (BEC) did not change morbidity as defined by weight loss, but mice at day 10 post-infection treated with BEC had gained significantly more weight back than controls. Neutrophil and macrophage infiltration were similar between groups in the lung parenchyma, and neutrophil migration into the airways was reduced by BEC treatment. Differences seem to lie in the impact on T cell subset disposition. Arg1ΔM mice had increased total CD4+ T cell expansion in the lymph nodes, and increased T cell activation, IFNγ production, and IL-17 production in the lymph nodes, lung interstitium, and airways, while treatment with BEC had no impact on T cell activation or IL-17 production, but reduced the number of T cells producing IFNγ in the lungs. Lung injury scores were increased in the Arg1ΔM mice, but no differences were observed in the mice treated with pharmacologic arginase inhibitors. Overall, myeloid arginase production was demonstrated to be essential for control of damaging inflammatory responses associated with P. aeruginosa pneumonia in C57BL/6 mice, in contrast to a protective effect in the Th2-dominant BALB/c mice when arginase activity is globally inhibited.
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Affiliation(s)
- Dalia Haydar
- University of Kentucky, Department of Pharmacy Practice and Science, 789 S. Limestone Street, Lexington, KY 40536, USA.
| | - Rene Gonzalez
- University of Kentucky, Department of Pharmacy Practice and Science, 789 S. Limestone Street, Lexington, KY 40536, USA.
| | - Beth A Garvy
- University of Kentucky, College of Medicine, Department of Microbiology, Immunology and Molecular Genetics, 800 Rose Street, Lexington, KY 40536, USA.
| | - Sylvie Garneau-Tsodikova
- University of Kentucky, College of Pharmacy, Department of Pharmaceutical Sciences, 789 S. Limestone Street, Lexington, KY 40536, USA.
| | - Nishad Thamban Chandrika
- University of Kentucky, College of Pharmacy, Department of Pharmaceutical Sciences, 789 S. Limestone Street, Lexington, KY 40536, USA.
| | - Therese J Bocklage
- University of Kentucky Healthcare, Pathology and Laboratory Medicine, 800 Rose Street, Lexington, KY 40536, USA.
| | - David J Feola
- University of Kentucky, Department of Pharmacy Practice and Science, 789 S. Limestone Street, Lexington, KY 40536, USA.
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10
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Alfituri OA, Quintana JF, MacLeod A, Garside P, Benson RA, Brewer JM, Mabbott NA, Morrison LJ, Capewell P. To the Skin and Beyond: The Immune Response to African Trypanosomes as They Enter and Exit the Vertebrate Host. Front Immunol 2020; 11:1250. [PMID: 32595652 PMCID: PMC7304505 DOI: 10.3389/fimmu.2020.01250] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/18/2020] [Indexed: 12/14/2022] Open
Abstract
African trypanosomes are single-celled extracellular protozoan parasites transmitted by tsetse fly vectors across sub-Saharan Africa, causing serious disease in both humans and animals. Mammalian infections begin when the tsetse fly penetrates the skin in order to take a blood meal, depositing trypanosomes into the dermal layer. Similarly, onward transmission occurs when differentiated and insect pre-adapted forms are ingested by the fly during a blood meal. Between these transmission steps, trypanosomes access the systemic circulation of the vertebrate host via the skin-draining lymph nodes, disseminating into multiple tissues and organs, and establishing chronic, and long-lasting infections. However, most studies of the immunobiology of African trypanosomes have been conducted under experimental conditions that bypass the skin as a route for systemic dissemination (typically via intraperitoneal or intravenous routes). Therefore, the importance of these initial interactions between trypanosomes and the skin at the site of initial infection, and the implications for these processes in infection establishment, have largely been overlooked. Recent studies have also demonstrated active and complex interactions between the mammalian host and trypanosomes in the skin during initial infection and revealed the skin as an overlooked anatomical reservoir for transmission. This highlights the importance of this organ when investigating the biology of trypanosome infections and the associated immune responses at the initial site of infection. Here, we review the mechanisms involved in establishing African trypanosome infections and potential of the skin as a reservoir, the role of innate immune cells in the skin during initial infection, and the subsequent immune interactions as the parasites migrate from the skin. We suggest that a thorough identification of the mechanisms involved in establishing African trypanosome infections in the skin and their progression through the host is essential for the development of novel approaches to interrupt disease transmission and control these important diseases.
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Affiliation(s)
- Omar A. Alfituri
- Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Juan F. Quintana
- Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Annette MacLeod
- Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Paul Garside
- Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Robert A. Benson
- Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - James M. Brewer
- Wellcome Centre for Integrative Parasitology, College of Medical, Veterinary and Life Sciences, Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Neil A. Mabbott
- Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Liam J. Morrison
- Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Paul Capewell
- College of Medical, Veterinary and Life Sciences, Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
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11
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Williams JL, Paudyal A, Awad S, Nicholson J, Grzesik D, Botta J, Meimaridou E, Maharaj AV, Stewart M, Tinker A, Cox RD, Metherell LA. Mylk3 null C57BL/6N mice develop cardiomyopathy, whereas Nnt null C57BL/6J mice do not. Life Sci Alliance 2020; 3:3/4/e201900593. [PMID: 32213617 PMCID: PMC7103425 DOI: 10.26508/lsa.201900593] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 03/10/2020] [Accepted: 03/10/2020] [Indexed: 12/30/2022] Open
Abstract
The C57BL/6J and C57BL/6N mice have well-documented phenotypic and genotypic differences, including the infamous nicotinamide nucleotide transhydrogenase (Nnt) null mutation in the C57BL/6J substrain, which has been linked to cardiovascular traits in mice and cardiomyopathy in humans. To assess whether Nnt loss alone causes a cardiovascular phenotype, we investigated the C57BL/6N, C57BL/6J mice and a C57BL/6J-BAC transgenic rescuing NNT expression, at 3, 12, and 18 mo. We identified a modest dilated cardiomyopathy in the C57BL/6N mice, absent in the two B6J substrains. Immunofluorescent staining of cardiomyocytes revealed eccentric hypertrophy in these mice, with defects in sarcomere organisation. RNAseq analysis identified differential expression of a number of cardiac remodelling genes commonly associated with cardiac disease segregating with the phenotype. Variant calling from RNAseq data identified a myosin light chain kinase 3 (Mylk3) mutation in C57BL/6N mice, which abolishes MYLK3 protein expression. These results indicate the C57BL/6J Nnt-null mice do not develop cardiomyopathy; however, we identified a null mutation in Mylk3 as a credible cause of the cardiomyopathy phenotype in the C57BL/6N.
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Affiliation(s)
- Jack L Williams
- Centre for Endocrinology, William Harvey Research Institute, Charterhouse Square, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Anju Paudyal
- Medical Research Council Harwell Institute, Mary Lyon Centre, Harwell Campus, Oxfordshire, UK
| | - Sherine Awad
- Centre for Endocrinology, William Harvey Research Institute, Charterhouse Square, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - James Nicholson
- Centre for Endocrinology, William Harvey Research Institute, Charterhouse Square, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Dominika Grzesik
- Centre for Endocrinology, William Harvey Research Institute, Charterhouse Square, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Joaquin Botta
- Centre for Endocrinology, William Harvey Research Institute, Charterhouse Square, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Eirini Meimaridou
- School of Human Sciences, London Metropolitan University, London, UK
| | - Avinaash V Maharaj
- Centre for Endocrinology, William Harvey Research Institute, Charterhouse Square, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Michelle Stewart
- Medical Research Council Harwell Institute, Mary Lyon Centre, Harwell Campus, Oxfordshire, UK
| | - Andrew Tinker
- William Harvey Heart Centre, William Harvey Research Institute, Charterhouse Square, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Roger D Cox
- Medical Research Council Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Oxfordshire, UK
| | - Lou A Metherell
- Centre for Endocrinology, William Harvey Research Institute, Charterhouse Square, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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12
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Solaymani-Mohammadi S, Eckmann L, Singer SM. Interleukin (IL)-21 in Inflammation and Immunity During Parasitic Diseases. Front Cell Infect Microbiol 2019; 9:401. [PMID: 31867283 PMCID: PMC6904299 DOI: 10.3389/fcimb.2019.00401] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 11/11/2019] [Indexed: 12/30/2022] Open
Abstract
Parasitic diseases cause significant morbidity and mortality in the developing and underdeveloped countries. No efficacious vaccines are available against most parasitic diseases and there is a critical need for developing novel vaccine strategies for care. IL-21 is a pleiotropic cytokine whose functions in protection and immunopathology during parasitic diseases have been explored in limited ways. IL-21 and its cognate receptor, IL-21R, are highly expressed in parasitized organs of infected humans as well in murine models of the human parasitic diseases. Prior studies have indicated the ability of the IL-21/IL-21R signaling axis to regulate the effector functions (e.g., cytokine production) of T cell subsets by enhancing the expression of T-bet and STAT4 in human T cells, resulting in an augmented production of IFN-γ. Mice deficient for either IL-21 (Il21−/−) or IL-21R (Il21r−/−) showed significantly reduced inflammatory responses following parasitic infections as compared with their WT counterparts. Targeting the IL-21/IL-21R signaling axis may provide a novel approach for the development of new therapeutic agents for the prevention of parasite-induced immunopathology and tissue destruction.
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Affiliation(s)
- Shahram Solaymani-Mohammadi
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Lars Eckmann
- Department of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Steven M Singer
- Department of Biology, Georgetown University, Washington, DC, United States
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13
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Latour YL, Gobert AP, Wilson KT. The role of polyamines in the regulation of macrophage polarization and function. Amino Acids 2019; 52:151-160. [PMID: 31016375 DOI: 10.1007/s00726-019-02719-0] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 03/04/2019] [Indexed: 01/18/2023]
Abstract
Naturally occurring polyamines are ubiquitously distributed and play important roles in cell development, amino acid and protein synthesis, oxidative DNA damage, proliferation, and cellular differentiation. Macrophages are essential in the innate immune response, and contribute to tissue remodeling. Naïve macrophages have two major potential fates: polarization to (1) the classical pro-inflammatory M1 defense response to bacterial pathogens and tumor cells, and (2) the alternatively activated M2 response, induced in the presence of parasites and wounding, and also implicated in the development of tumor-associated macrophages. ODC, the rate-limiting enzyme in polyamine synthesis, leads to an increase in putrescine levels, which impairs M1 gene transcription. Additionally, spermidine and spermine can regulate translation of pro-inflammatory mediators in activated macrophages. In this review, we focus on polyamines in macrophage activation patterns in the context of gastrointestinal inflammation and carcinogenesis. We seek to clarify mechanisms of innate immune regulation by polyamine metabolism and potential novel therapeutic targets.
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Affiliation(s)
- Yvonne L Latour
- Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Vanderbilt University School of Medicine, 2215 Garland Avenue, Room 1030C Medical Research Building IV, Nashville, TN, 37232, USA.,Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alain P Gobert
- Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Vanderbilt University School of Medicine, 2215 Garland Avenue, Room 1030C Medical Research Building IV, Nashville, TN, 37232, USA.,Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, USA
| | - Keith T Wilson
- Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Vanderbilt University School of Medicine, 2215 Garland Avenue, Room 1030C Medical Research Building IV, Nashville, TN, 37232, USA. .,Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA. .,Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, USA. .,Program in Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN, USA. .,Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA.
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14
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Abad Dar M, Hölscher C. Arginase-1 Is Responsible for IL-13-Mediated Susceptibility to Trypanosoma cruzi Infection. Front Immunol 2018; 9:2790. [PMID: 30555475 PMCID: PMC6281981 DOI: 10.3389/fimmu.2018.02790] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 11/13/2018] [Indexed: 01/17/2023] Open
Abstract
Arginase-1 (Arg-1) is a marker for alternatively activated macrophages (AAM) and is mainly induced by the type 2 cytokines interleukin (IL)-4 and IL-13 through the common IL-4 receptor-alpha (Rα) subunit. Both, Arg-1 and AAM undermine macrophage effector functions against intracellular parasites and are therefore implicated in the susceptibility to infection with Trypanosoma cruzi, the causative agent of Chagas' disease. However, the involvement of Arg-1 in promoting intracellular replication of T. cruzi in AAM has not been proven so far in vivo. Because Arg-1 is only moderately expressed in T. cruzi-infected wildtype mice, we elucidated the role of Arg-1 and AAM during infection in IL-13-overexpressing (IL-13tg) mice, which are characterized by an inflammation-induced development of AAM and an accompanied elevated expression of Arg-1. In comparison to wildtype littermates, IL-13tg mice were highly susceptible to T. cruzi infection with enhanced parasitemia and impaired survival. Importantly, T. cruzi-infected IL-13tg mice developed an elevated alternative macrophage activation with increased arginase activity. To proof the hypothesis, that Arg-1 accounts for the increased susceptibility of IL-13tg mice, we blocked arginase activity in infected IL-13tg mice. Because this arginase inhibition resulted in a decreased susceptibility to experimental Chagas disease our study supports in summary the conclusion that IL-13/IL-4Rα-driven Arg-1 expression contributes to the permissiveness of the host to T. cruzi infection.
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Affiliation(s)
- Mahin Abad Dar
- Infection Immunology, Research Center Borstel, Borstel, Germany
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15
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Guo X, Chen Y, Seto CT. Rational design of novel irreversible inhibitors for human arginase. Bioorg Med Chem 2018; 26:3939-3946. [PMID: 29914772 DOI: 10.1016/j.bmc.2018.06.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/05/2018] [Accepted: 06/13/2018] [Indexed: 01/10/2023]
Abstract
Parasites have developed a variety of strategies for invading hosts and escaping their immune response. A common mechanism by which parasites escape nitric oxide (NO) toxicity is the activation of host arginase. This activation leads to a depletion of l-arginine, which is the substrate for NO synthase, resulting in lower levels of NO and increased production of polyamines that are necessary for parasite growth and differentiation. For this reason, small molecule inhibitors for arginase show promise as new anti-parasitic chemotherapeutics. However, few arginase inhibitors have been reported. Here, we describe the discovery of novel irreversible arginase inhibitors, and their characterization using biochemical, kinetic, and structural studies. Importantly, we determined the site on human arginase that is labeled by one of the small molecule inhibitors. The tandem mass spectra data show that the inhibitor occupies the enzyme active site and forms a covalent bond with Thr135 of arginase. These findings pave the way for the development of more potent and selective irreversible arginase inhibitors.
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Affiliation(s)
- Xuefeng Guo
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Yiming Chen
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Christopher T Seto
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.
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16
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Holzmuller P, Geiger A, Nzoumbou-Boko R, Pissarra J, Hamrouni S, Rodrigues V, Dauchy FA, Lemesre JL, Vincendeau P, Bras-Gonçalves R. Trypanosomatid Infections: How Do Parasites and Their Excreted-Secreted Factors Modulate the Inducible Metabolism of l-Arginine in Macrophages? Front Immunol 2018; 9:778. [PMID: 29731753 PMCID: PMC5921530 DOI: 10.3389/fimmu.2018.00778] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 03/28/2018] [Indexed: 12/20/2022] Open
Abstract
Mononuclear phagocytes (monocytes, dendritic cells, and macrophages) are among the first host cells to face intra- and extracellular protozoan parasites such as trypanosomatids, and significant expansion of macrophages has been observed in infected hosts. They play essential roles in the outcome of infections caused by trypanosomatids, as they can not only exert a powerful antimicrobial activity but also promote parasite proliferation. These varied functions, linked to their phenotypic and metabolic plasticity, are exerted via distinct activation states, in which l-arginine metabolism plays a pivotal role. Depending on the environmental factors and immune response elements, l-arginine metabolites contribute to parasite elimination, mainly through nitric oxide (NO) synthesis, or to parasite proliferation, through l-ornithine and polyamine production. To survive and adapt to their hosts, parasites such as trypanosomatids developed mechanisms of interaction to modulate macrophage activation in their favor, by manipulating several cellular metabolic pathways. Recent reports emphasize that some excreted-secreted (ES) molecules from parasites and sugar-binding host receptors play a major role in this dialog, particularly in the modulation of the macrophage's inducible l-arginine metabolism. Preventing l-arginine dysregulation by drugs or by immunization against trypanosomatid ES molecules or by blocking partner host molecules may control early infection and is a promising way to tackle neglected diseases including Chagas disease, leishmaniases, and African trypanosomiases. The present review summarizes recent knowledge on trypanosomatids and their ES factors with regard to their influence on macrophage activation pathways, mainly the NO synthase/arginase balance. The review ends with prospects for the use of biological knowledge to develop new strategies of interference in the infectious processes used by trypanosomatids, in particular for the development of vaccines or immunotherapeutic approaches.
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Affiliation(s)
- Philippe Holzmuller
- CIRAD, Montpellier, France.,UMR 117 ASTRE "Animal, Santé, Territoire, Risques et Ecosystèmes", Univ. Montpellier (I-MUSE), CIRAD, INRA, Montpellier, France
| | - Anne Geiger
- UMR 177 INTERTRYP "Interactions Hôte-Vecteur-Parasite-Environnement dans les maladies tropicales négligées dues aux Trypanosomatidae", Univ. Montpellier (I-MUSE), CIRAD, IRD, Univ. Bordeaux 2, Univ. Lyon 1, Montpellier, France
| | - Romaric Nzoumbou-Boko
- UMR 177 INTERTRYP "Interactions Hôte-Vecteur-Parasite-Environnement dans les maladies tropicales négligées dues aux Trypanosomatidae", Univ. Montpellier (I-MUSE), CIRAD, IRD, Univ. Bordeaux 2, Univ. Lyon 1, Montpellier, France.,Univ. Bordeaux, UMR 177 INTERTRYP, Bordeaux, France.,CHU Bordeaux, Laboratoire de Parasitologie-Mycologie, Bordeaux, France
| | - Joana Pissarra
- UMR 177 INTERTRYP "Interactions Hôte-Vecteur-Parasite-Environnement dans les maladies tropicales négligées dues aux Trypanosomatidae", Univ. Montpellier (I-MUSE), CIRAD, IRD, Univ. Bordeaux 2, Univ. Lyon 1, Montpellier, France
| | - Sarra Hamrouni
- UMR 177 INTERTRYP "Interactions Hôte-Vecteur-Parasite-Environnement dans les maladies tropicales négligées dues aux Trypanosomatidae", Univ. Montpellier (I-MUSE), CIRAD, IRD, Univ. Bordeaux 2, Univ. Lyon 1, Montpellier, France
| | - Valérie Rodrigues
- CIRAD, Montpellier, France.,UMR 117 ASTRE "Animal, Santé, Territoire, Risques et Ecosystèmes", Univ. Montpellier (I-MUSE), CIRAD, INRA, Montpellier, France
| | - Frédéric-Antoine Dauchy
- UMR 177 INTERTRYP "Interactions Hôte-Vecteur-Parasite-Environnement dans les maladies tropicales négligées dues aux Trypanosomatidae", Univ. Montpellier (I-MUSE), CIRAD, IRD, Univ. Bordeaux 2, Univ. Lyon 1, Montpellier, France.,Univ. Bordeaux, UMR 177 INTERTRYP, Bordeaux, France.,CHU Bordeaux, Département des Maladies Infectieuses et Tropicales, Bordeaux, France
| | - Jean-Loup Lemesre
- UMR 177 INTERTRYP "Interactions Hôte-Vecteur-Parasite-Environnement dans les maladies tropicales négligées dues aux Trypanosomatidae", Univ. Montpellier (I-MUSE), CIRAD, IRD, Univ. Bordeaux 2, Univ. Lyon 1, Montpellier, France
| | - Philippe Vincendeau
- UMR 177 INTERTRYP "Interactions Hôte-Vecteur-Parasite-Environnement dans les maladies tropicales négligées dues aux Trypanosomatidae", Univ. Montpellier (I-MUSE), CIRAD, IRD, Univ. Bordeaux 2, Univ. Lyon 1, Montpellier, France.,Univ. Bordeaux, UMR 177 INTERTRYP, Bordeaux, France.,CHU Bordeaux, Laboratoire de Parasitologie-Mycologie, Bordeaux, France
| | - Rachel Bras-Gonçalves
- UMR 177 INTERTRYP "Interactions Hôte-Vecteur-Parasite-Environnement dans les maladies tropicales négligées dues aux Trypanosomatidae", Univ. Montpellier (I-MUSE), CIRAD, IRD, Univ. Bordeaux 2, Univ. Lyon 1, Montpellier, France
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17
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Insights into the role of endonuclease V in RNA metabolism in Trypanosoma brucei. Sci Rep 2017; 7:8505. [PMID: 28819113 PMCID: PMC5561087 DOI: 10.1038/s41598-017-08910-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/14/2017] [Indexed: 01/05/2023] Open
Abstract
Inosine may arise in DNA as a result of oxidative deamination of adenine or misincorporation of deoxyinosine triphosphate during replication. On the other hand, the occurrence of inosine in RNA is considered a normal and essential modification induced by specific adenosine deaminases acting on mRNA and tRNA. In prokaryotes, endonuclease V (EndoV) can recognize and cleave inosine-containing DNA. In contrast, mammalian EndoVs preferentially cleave inosine-containing RNA, suggesting a role in RNA metabolism for the eukaryotic members of this protein family. We have performed a biochemical characterization of EndoV from the protozoan parasite Trypanosoma brucei. In vitro, TbEndoV efficiently processes single-stranded RNA oligonucleotides with inosine, including A to I-edited tRNA-like substrates but exhibits weak activity over DNA, except when a ribonucleotide is placed 3' to the inosine. Immunolocalization studies performed in procyclic forms indicate that TbEndoV is mainly cytosolic yet upon nutritional stress it redistributes and accumulates in stress granules colocalizing with the DEAD-box helicase TbDhh1. RNAi-mediated depletion of TbEndoV results in moderate growth defects in procyclic cells while the two EndoV alleles could be readily knocked out in bloodstream forms. Taken together, these observations suggest an important role of TbEndoV in RNA metabolism in procyclic forms of the parasite.
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18
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Nzoumbou-Boko R, De Muylder G, Semballa S, Lecordier L, Dauchy FA, Gobert AP, Holzmuller P, Lemesre JL, Bras-Gonçalves R, Barnabé C, Courtois P, Daulouède S, Beschin A, Pays E, Vincendeau P. Trypanosoma musculiInfection in Mice Critically Relies on Mannose Receptor–Mediated Arginase Induction by aTbKHC1 Kinesin H Chain Homolog. THE JOURNAL OF IMMUNOLOGY 2017; 199:1762-1771. [DOI: 10.4049/jimmunol.1700179] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 06/20/2017] [Indexed: 01/26/2023]
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19
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Macedo JP, Currier RB, Wirdnam C, Horn D, Alsford S, Rentsch D. Ornithine uptake and the modulation of drug sensitivity in Trypanosoma brucei. FASEB J 2017; 31:4649-4660. [PMID: 28679527 PMCID: PMC5602898 DOI: 10.1096/fj.201700311r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 06/27/2017] [Indexed: 12/02/2022]
Abstract
Trypanosoma brucei, protozoan parasites that cause human African trypanosomiasis (HAT), depend on ornithine uptake and metabolism by ornithine decarboxylase (ODC) for survival. Indeed, ODC is the target of the WHO “essential medicine” eflornithine, which is antagonistic to another anti-HAT drug, suramin. Thus, ornithine uptake has important consequences in T. brucei, but the transporters have not been identified. We describe these amino acid transporters (AATs). In a heterologous expression system, TbAAT10-1 is selective for ornithine, whereas TbAAT2-4 transports both ornithine and histidine. These AATs are also necessary to maintain intracellular ornithine and polyamine levels in T. brucei, thereby decreasing sensitivity to eflornithine and increasing sensitivity to suramin. Consistent with competition for histidine, high extracellular concentrations of this amino acid phenocopied a TbAAT2-4 genetic defect. Our findings established TbAAT10-1 and TbAAT2-4 as the parasite ornithine transporters, one of which can be modulated by histidine, but both of which affect sensitivity to important anti-HAT drugs.—Macedo, J. P., Currier, R. B., Wirdnam, C., Horn, D., Alsford, S., Rentsch, D. Ornithine uptake and the modulation of drug sensitivity in Trypanosoma brucei.
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Affiliation(s)
- Juan P Macedo
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Rachel B Currier
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Corina Wirdnam
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - David Horn
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Sam Alsford
- London School of Hygiene and Tropical Medicine, London, United Kingdom;
| | - Doris Rentsch
- Institute of Plant Sciences, University of Bern, Bern, Switzerland;
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20
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Geiger A, Bossard G, Sereno D, Pissarra J, Lemesre JL, Vincendeau P, Holzmuller P. Escaping Deleterious Immune Response in Their Hosts: Lessons from Trypanosomatids. Front Immunol 2016; 7:212. [PMID: 27303406 PMCID: PMC4885876 DOI: 10.3389/fimmu.2016.00212] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 05/17/2016] [Indexed: 12/21/2022] Open
Abstract
The Trypanosomatidae family includes the genera Trypanosoma and Leishmania, protozoan parasites displaying complex digenetic life cycles requiring a vertebrate host and an insect vector. Trypanosoma brucei gambiense, Trypanosoma cruzi, and Leishmania spp. are important human pathogens causing human African trypanosomiasis (HAT or sleeping sickness), Chagas' disease, and various clinical forms of Leishmaniasis, respectively. They are transmitted to humans by tsetse flies, triatomine bugs, or sandflies, and affect millions of people worldwide. In humans, extracellular African trypanosomes (T. brucei) evade the hosts' immune defenses, allowing their transmission to the next host, via the tsetse vector. By contrast, T. cruzi and Leishmania sp. have developed a complex intracellular lifestyle, also preventing several mechanisms to circumvent the host's immune response. This review seeks to set out the immune evasion strategies developed by the different trypanosomatids resulting from parasite-host interactions and will focus on: clinical and epidemiological importance of diseases; life cycles: parasites-hosts-vectors; innate immunity: key steps for trypanosomatids in invading hosts; deregulation of antigen-presenting cells; disruption of efficient specific immunity; and the immune responses used for parasite proliferation.
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Affiliation(s)
- Anne Geiger
- UMR INTERTRYP, IRD-CIRAD, CIRAD TA A-17/G, Montpellier, France
| | | | - Denis Sereno
- UMR INTERTRYP, IRD-CIRAD, CIRAD TA A-17/G, Montpellier, France
| | - Joana Pissarra
- UMR INTERTRYP, IRD-CIRAD, CIRAD TA A-17/G, Montpellier, France
| | | | - Philippe Vincendeau
- UMR 177, IRD-CIRAD Université de Bordeaux Laboratoire de Parasitologie, Bordeaux, France
| | - Philippe Holzmuller
- UMRCMAEE CIRAD-INRA TA-A15/G “Contrôle des maladies animales exotiques et émergentes”, Montpellier, France
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Van Vinh Chau N, Buu Chau L, Desquesnes M, Herder S, Phu Huong Lan N, Campbell JI, Van Cuong N, Yimming B, Chalermwong P, Jittapalapong S, Ramon Franco J, Tri Tue N, Rabaa MA, Carrique-Mas J, Pham Thi Thanh T, Tran Vu Thieu N, Berto A, Thi Hoa N, Van Minh Hoang N, Canh Tu N, Khac Chuyen N, Wills B, Tinh Hien T, Thwaites GE, Yacoub S, Baker S. A Clinical and Epidemiological Investigation of the First Reported Human Infection With the Zoonotic Parasite Trypanosoma evansi in Southeast Asia. Clin Infect Dis 2016; 62:1002-1008. [PMID: 26908809 PMCID: PMC4803109 DOI: 10.1093/cid/ciw052] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 01/27/2016] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Trypanosomais a genus of unicellular parasitic flagellate protozoa.Trypanosoma bruceispecies and Trypanosoma cruziare the major agents of human trypanosomiasis; other Trypanosomaspecies can cause human disease, but are rare. In March 2015, a 38-year-old woman presented to a healthcare facility in southern Vietnam with fever, headache, and arthralgia. Microscopic examination of blood revealed infection with Trypanosoma METHODS Microscopic observation, polymerase chain reaction (PCR) amplification of blood samples, and serological testing were performed to identify the infecting species. The patient's blood was screened for the trypanocidal protein apolipoprotein L1 (APOL1), and a field investigation was performed to identify the zoonotic source. RESULTS PCR amplification and serological testing identified the infecting species as Trypanosoma evansi.Despite relapsing 6 weeks after completing amphotericin B therapy, the patient made a complete recovery after 5 weeks of suramin. The patient was found to have 2 wild-type APOL1 alleles and a normal serum APOL1 concentration. After responsive animal sampling in the presumed location of exposure, cattle and/or buffalo were determined to be the most likely source of the infection, with 14 of 30 (47%) animal blood samples testing PCR positive forT. evansi. CONCLUSIONS We report the first laboratory-confirmed case ofT. evansiin a previously healthy individual without APOL1 deficiency, potentially contracted via a wound while butchering raw beef, and successfully treated with suramin. A linked epidemiological investigation revealed widespread and previously unidentified burden ofT. evansiin local cattle, highlighting the need for surveillance of this infection in animals and the possibility of further human cases.
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Affiliation(s)
| | - Le Buu Chau
- Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Marc Desquesnes
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), UMR Intertryp, Montpellier, France
- Department of Parasitology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand
| | - Stephane Herder
- Department of Parasitology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand
- UMR 177 Intertryp IRD/CIRAD, Montpellier, France
| | | | - James I Campbell
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Oxford University, United Kingdom
| | - Nguyen Van Cuong
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Benjarat Yimming
- Department of Parasitology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand
| | - Piangjai Chalermwong
- Department of Parasitology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand
| | - Sathaporn Jittapalapong
- Department of Parasitology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand
| | - Jose Ramon Franco
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Ngo Tri Tue
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Maia A Rabaa
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Oxford University, United Kingdom
| | - Juan Carrique-Mas
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Oxford University, United Kingdom
| | - Tam Pham Thi Thanh
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Nga Tran Vu Thieu
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Alessandra Berto
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Oxford University, United Kingdom
| | - Ngo Thi Hoa
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Oxford University, United Kingdom
| | - Nguyen Van Minh Hoang
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | | | | | - Bridget Wills
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Oxford University, United Kingdom
| | - Tran Tinh Hien
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Oxford University, United Kingdom
| | - Guy E Thwaites
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Oxford University, United Kingdom
| | - Sophie Yacoub
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Department of Medicine, Imperial College London, Hammersmith Campus
| | - Stephen Baker
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, Oxford University, United Kingdom
- Department of Pathogen and Molecular Biology, London School of Hygiene and Tropical Medicine, United Kingdom
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Amri M, Touil-Boukoffa C. A protective effect of the laminated layer on Echinococcus granulosus survival dependent on upregulation of host arginase. Acta Trop 2015; 149:186-94. [PMID: 26048557 DOI: 10.1016/j.actatropica.2015.05.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 05/26/2015] [Accepted: 05/29/2015] [Indexed: 12/11/2022]
Abstract
The role of nitric oxide (NO) in host defense against Echinococcus granulosus larvae was previously reported. However, NO production by NOS2 (inducible NO synthase) is counteracted by the expression of Arginase. In the present study, our aim is to evaluate the involvement of the laminated layer (external layer of parasitic cyst) in Arginase induction and the protoscoleces (living and infective part of the cyst) survival. Our in vitro results indicate that this cystic compound increases the Arginase activity in macrophages. Moreover, C-type lectin receptors (CLRs) with specificity for mannan and the TGF-β are implicated in this effect as shown after adding Mannan and Anti-TGFβ. Interestingly, the laminated layer increases protoscoleces survival in macrophages-parasite co-cultures. Our results indicate that the laminated layer protects E. granulosus against the NOS2 protective response through Arginase pathway, a hallmark of M2 macrophages.
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Macrophage arginase-1 controls bacterial growth and pathology in hypoxic tuberculosis granulomas. Proc Natl Acad Sci U S A 2014; 111:E4024-32. [PMID: 25201986 DOI: 10.1073/pnas.1408839111] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Lung granulomas develop upon Mycobacterium tuberculosis (Mtb) infection as a hallmark of human tuberculosis (TB). They are structured aggregates consisting mainly of Mtb-infected and -uninfected macrophages and Mtb-specific T cells. The production of NO by granuloma macrophages expressing nitric oxide synthase-2 (NOS2) via l-arginine and oxygen is a key protective mechanism against mycobacteria. Despite this protection, TB granulomas are often hypoxic, and bacterial killing via NOS2 in these conditions is likely suboptimal. Arginase-1 (Arg1) also metabolizes l-arginine but does not require oxygen as a substrate and has been shown to regulate NOS2 via substrate competition. However, in other infectious diseases in which granulomas occur, such as leishmaniasis and schistosomiasis, Arg1 plays additional roles such as T-cell regulation and tissue repair that are independent of NOS2 suppression. To address whether Arg1 could perform similar functions in hypoxic regions of TB granulomas, we used a TB murine granuloma model in which NOS2 is absent. Abrogation of Arg1 expression in macrophages in this setting resulted in exacerbated lung granuloma pathology and bacterial burden. Arg1 expression in hypoxic granuloma regions correlated with decreased T-cell proliferation, suggesting that Arg1 regulation of T-cell immunity is involved in disease control. Our data argue that Arg1 plays a central role in the control of TB when NOS2 is rendered ineffective by hypoxia.
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De Muylder G, Daulouède S, Lecordier L, Uzureau P, Morias Y, Van Den Abbeele J, Caljon G, Hérin M, Holzmuller P, Semballa S, Courtois P, Vanhamme L, Stijlemans B, De Baetselier P, Barrett MP, Barlow JL, McKenzie ANJ, Barron L, Wynn TA, Beschin A, Vincendeau P, Pays E. A Trypanosoma brucei kinesin heavy chain promotes parasite growth by triggering host arginase activity. PLoS Pathog 2013; 9:e1003731. [PMID: 24204274 PMCID: PMC3814429 DOI: 10.1371/journal.ppat.1003731] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 09/11/2013] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND In order to promote infection, the blood-borne parasite Trypanosoma brucei releases factors that upregulate arginase expression and activity in myeloid cells. METHODOLOGY/PRINCIPAL FINDINGS By screening a cDNA library of T. brucei with an antibody neutralizing the arginase-inducing activity of parasite released factors, we identified a Kinesin Heavy Chain isoform, termed TbKHC1, as responsible for this effect. Following interaction with mouse myeloid cells, natural or recombinant TbKHC1 triggered SIGN-R1 receptor-dependent induction of IL-10 production, resulting in arginase-1 activation concomitant with reduction of nitric oxide (NO) synthase activity. This TbKHC1 activity was IL-4Rα-independent and did not mirror M2 activation of myeloid cells. As compared to wild-type T. brucei, infection by TbKHC1 KO parasites was characterized by strongly reduced parasitaemia and prolonged host survival time. By treating infected mice with ornithine or with NO synthase inhibitor, we observed that during the first wave of parasitaemia the parasite growth-promoting effect of TbKHC1-mediated arginase activation resulted more from increased polyamine production than from reduction of NO synthesis. In late stage infection, TbKHC1-mediated reduction of NO synthesis appeared to contribute to liver damage linked to shortening of host survival time. CONCLUSION A kinesin heavy chain released by T. brucei induces IL-10 and arginase-1 through SIGN-R1 signaling in myeloid cells, which promotes early trypanosome growth and favors parasite settlement in the host. Moreover, in the late stage of infection, the inhibition of NO synthesis by TbKHC1 contributes to liver pathogenicity.
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Affiliation(s)
- Géraldine De Muylder
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Sylvie Daulouède
- Laboratoire de Parasitologie, UMR 177 IRD CIRAD Université de Bordeaux, Bordeaux, France
| | - Laurence Lecordier
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Pierrick Uzureau
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Yannick Morias
- Myeloid Cell Immunology Laboratory, VIB Brussels, Brussels, Belgium
- Cellular and Molecular Immunology Unit, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Jan Van Den Abbeele
- Department of Biomedical Sciences, Veterinary Protozoology Unit, Prins Leopold Institute of Tropical Medicine Antwerp, Antwerp, Belgium
| | - Guy Caljon
- Myeloid Cell Immunology Laboratory, VIB Brussels, Brussels, Belgium
- Cellular and Molecular Immunology Unit, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- Department of Biomedical Sciences, Veterinary Protozoology Unit, Prins Leopold Institute of Tropical Medicine Antwerp, Antwerp, Belgium
| | - Michel Hérin
- Department of Pathology, Institut de Pathologie et de Génétique, Gosselies, Belgium
| | - Philippe Holzmuller
- Laboratoire de Parasitologie, UMR 177 IRD CIRAD Université de Bordeaux, Bordeaux, France
| | - Silla Semballa
- Laboratoire de Parasitologie, UMR 177 IRD CIRAD Université de Bordeaux, Bordeaux, France
| | - Pierrette Courtois
- Laboratoire de Parasitologie, UMR 177 IRD CIRAD Université de Bordeaux, Bordeaux, France
| | - Luc Vanhamme
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Benoît Stijlemans
- Myeloid Cell Immunology Laboratory, VIB Brussels, Brussels, Belgium
- Cellular and Molecular Immunology Unit, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Patrick De Baetselier
- Myeloid Cell Immunology Laboratory, VIB Brussels, Brussels, Belgium
- Cellular and Molecular Immunology Unit, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Michael P. Barrett
- The Wellcome Trust Centre for Molecular Parasitology, Institute for Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- Glasgow Polyomics Facility, University of Glasgow, Glasgow, United Kingdom
| | - Jillian L. Barlow
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, United Kingdom
| | - Andrew N. J. McKenzie
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, United Kingdom
| | - Luke Barron
- Immunopathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Thomas A. Wynn
- Immunopathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Alain Beschin
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), Gosselies, Belgium
- Myeloid Cell Immunology Laboratory, VIB Brussels, Brussels, Belgium
- Cellular and Molecular Immunology Unit, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- * E-mail:
| | - Philippe Vincendeau
- Laboratoire de Parasitologie, UMR 177 IRD CIRAD Université de Bordeaux, Bordeaux, France
| | - Etienne Pays
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles (ULB), Gosselies, Belgium
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Bossard G, Cuny G, Geiger A. Secreted proteases of Trypanosoma brucei gambiense: possible targets for sleeping sickness control? Biofactors 2013; 39:407-14. [PMID: 23553721 DOI: 10.1002/biof.1100] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 02/01/2013] [Indexed: 01/09/2023]
Abstract
Human African trypanosomiasis (HAT) is caused by trypanosomes of the species Trypanosoma brucei and belongs to the neglected tropical diseases. Presently, WHO has listed 36 countries as being endemic for sleeping sickness. No vaccine is available, and disease treatment is difficult and has life-threatening side effects. Therefore, there is a crucial need to search for new therapeutic targets against the parasite. Trypanosome excreted-secreted proteins could be promising targets, as the total secretome was shown to inhibit, in vitro, host dendritic cell maturation and their ability to induce lymphocytic allogenic responses. The secretome was found surprisingly rich in various proteins and unexpectedly rich in diverse peptidases, covering more than ten peptidase families or subfamilies. Given their abundance, one may speculate that they would play a genuine role not only in classical "housekeeping" tasks but also in pathogenesis. The paper reviews the deleterious role of proteases from trypanosomes, owing to their capacity to degrade host circulating or structural proteins, as well as proteic hormones, causing severe damage and preventing host immune response. In addition, proteases account for a number of drug targets, such drugs being used to treat severe diseases such AIDS. This review underlines the importance of secreted proteins and especially of secreted proteases as potential targets in HAT-fighting strategies. It points out the need to conduct further investigations on the specific role of each of these various proteases in order to identify those playing a central role in sleeping sickness and would be suitable for drug targeting.
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Affiliation(s)
- Géraldine Bossard
- UMR 177, IRD-CIRAD, CIRAD TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
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The Trypanosoma brucei gambiense secretome impairs lipopolysaccharide-induced maturation, cytokine production, and allostimulatory capacity of dendritic cells. Infect Immun 2013; 81:3300-8. [PMID: 23798533 DOI: 10.1128/iai.00125-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Trypanosoma brucei gambiense, a parasitic protozoan belonging to kinetoplastids, is the main etiological agent of human African trypanosomiasis (HAT), or sleeping sickness. One major characteristic of this disease is the dysregulation of the host immune system. The present study demonstrates that the secretome (excreted-secreted proteins) of T. b. gambiense impairs the lipopolysaccharide (LPS)-induced maturation of murine dendritic cells (DCs). The upregulation of major histocompatibility complex class II, CD40, CD80, and CD86 molecules, as well as the secretion of cytokines such as tumor necrosis factor alpha, interleukin-10 (IL-10), and IL-6, which are normally released at high levels by LPS-stimulated DCs, is significantly reduced when these cells are cultured in the presence of the T. b. gambiense secretome. Moreover, the inhibition of DC maturation results in the loss of their allostimulatory capacity, leading to a dramatic decrease in Th1/Th2 cytokine production by cocultured lymphocytes. These results provide new insights into a novel efficient immunosuppressive mechanism directly involving the alteration of DC function which might be used by T. b. gambiense to interfere with the host immune responses in HAT and promote the infectious process.
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Serum arginase, a biomarker of treatment efficacy in human African trypanosomiasis. J Clin Microbiol 2013; 51:2379-81. [PMID: 23554207 DOI: 10.1128/jcm.03371-12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Arginase serum levels were increased in human African trypanosomiasis patients and returned to control values after treatment. Arginase hydrolyzes l-arginine to l-ornithine, which is essential for parasite growth. Moreover, l-arginine depletion impairs immune functions. Arginase may be considered as a biomarker for treatment efficacy.
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Tabel H, Wei G, Bull HJ. Immunosuppression: cause for failures of vaccines against African Trypanosomiases. PLoS Negl Trop Dis 2013; 7:e2090. [PMID: 23516643 PMCID: PMC3597477 DOI: 10.1371/journal.pntd.0002090] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Henry Tabel
- Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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Vinogradov SN, Bailly X, Smith DR, Tinajero-Trejo M, Poole RK, Hoogewijs D. Microbial eukaryote globins. Adv Microb Physiol 2013; 63:391-446. [PMID: 24054801 DOI: 10.1016/b978-0-12-407693-8.00009-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A bioinformatics survey of about 120 protist and 240 fungal genomes and transcriptomes revealed a broad array of globins, representing five of the eight subfamilies identified in bacteria. Most conspicuous is the absence of protoglobins and globin-coupled sensors, except for a two-domain globin in Leishmanias, that comprises a nucleotidyl cyclase domain, and the virtual absence of truncated group 3 globins. In contrast to bacteria, co-occurrence of more than two globin subfamilies appears to be rare in protists. Although globins were lacking in the Apicomplexa and the Microsporidia intracellular pathogens, they occurred in the pathogenic Trypanosomatidae, Stramenopiles and certain fungi. Flavohaemoglobins (FHbs) and related single-domain globins occur across the protist groups. Fungi are unique in having FHbs co-occurring with sensor single-domain globins (SSDgbs). Obligately biotrophic fungi covered in our analysis lack globins. Furthermore, SSDgbs occur only in a heterolobosean amoeba, Naegleria and the stramenopile Hyphochytrium. Of the three subfamilies of truncated Mb-fold globins, TrHb1s appear to be the most widespread, occurring as multiple copies in chlorophyte and ciliophora genomes, many as multidomain proteins. Although the ciliates appear to have only TrHb1s, the chlorophytes have Mb-like globins and TrHb2s, both closely related to the corresponding plant globins. The presently available number of protist genomes is inadequate to provide a definitive census of their globins. Bayesian molecular analyses of single-domain 3/3 Mb-fold globins suggest a close relationship of chlorophyte and haptophyte globins, including choanoflagellate and Capsaspora globins to land plant symbiotic and non-symbiotic haemoglobins and to vertebrate neuroglobins.
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Contribution of Innate Immune Responses towards Resistance to African Trypanosome Infections. Scand J Immunol 2011; 75:5-15. [DOI: 10.1111/j.1365-3083.2011.02619.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Oladiran A, Belosevic M. Immune evasion strategies of trypanosomes: a review. J Parasitol 2011; 98:284-92. [PMID: 22007969 DOI: 10.1645/ge-2925.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Trypanosomes are digenetic protozoans that infect domestic and wild animals, as well as humans. They cause important medical and veterinary diseases, making them a major public health concern. There are many species of trypanosomes that infect virtually all vertebrate taxa. They typically cycle between insect or leech vectors and vertebrate hosts, and they undergo biochemical and morphological changes in the process. Trypanosomes have received much attention in the last 4 decades because of the diseases they cause and their remarkable armamentarium of immune evasion mechanisms. The completed genome sequences of trypanosomes have revealed an extensive array of molecules that contribute to various immune evasion mechanisms. The different species interact uniquely with their vertebrate hosts with a wide range of evasion strategies and some of the most fascinating immune evasion mechanisms, including antigenic variation that was first described in the trypanosomes. This review focuses on the variety of strategies that these parasites have evolved to evade or modulate immunity of endothermic and ectothermic vertebrates.
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Affiliation(s)
- Ayoola Oladiran
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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Chaturvedi R, de Sablet T, Coburn LA, Gobert AP, Wilson KT. Arginine and polyamines in Helicobacter pylori-induced immune dysregulation and gastric carcinogenesis. Amino Acids 2011; 42:627-40. [PMID: 21874531 DOI: 10.1007/s00726-011-1038-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 06/13/2011] [Indexed: 02/07/2023]
Abstract
L-arginine (L-Arg) is metabolized by nitric oxide synthase and arginase enzymes. The gastric pathogen Helicobacter pylori causes peptic ulcer disease and gastric cancer. We have shown that alterations in L-Arg availability and metabolism into polyamines contribute significantly to the dysregulation of the host immune response to this infection. Nitric oxide (NO) derived from inducible NO synthase (iNOS) can kill H. pylori. There are multiple mechanisms leading to failure of this process, including competition for L-Arg substrate by H. pylori arginase, and induction of host macrophage arginase II (Arg2) and ornithine decarboxylase (ODC). Generation of spermine by ODC inhibits iNOS translation and NO-mediated H. pylori killing. Expression of ODC is dependent on formation of a unique AP-1 complex, leading to upregulation of c-Myc as a transcriptional enhancer. Macrophage apoptosis is mediated by oxidation of spermine via the enzyme spermine oxidase (SMO) that generates hydrogen peroxide (H(2)O(2)), and thus oxidative stress-induced mitochondrial membrane polarization. Our studies have demonstrated that apoptosis occurs through a pERK → pc-Fos/c-Jun → c-Myc → ODC → SMO pathway. In gastric epithelial cells, activation of oxidative stress by H. pylori is dependent on SMO induction and results in both apoptosis and DNA damage, such that inhibition or knockdown of SMO markedly attenuates these events. In summary, L-Arg metabolism by the arginase-ODC pathway and the activation of SMO leads to H. pylori-induced DNA damage and immune dysregulation through polyamine-mediated oxidative stress and impairment of antimicrobial NO synthesis. Our studies indicate novel targets for therapeutic intervention in H. pylori-associated diseases, including gastritis, ulcer disease, and gastric cancer.
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Affiliation(s)
- Rupesh Chaturvedi
- Division of Gastroenterology, Department of Medicine, Vanderbilt University School of Medicine, 1030C MRBIV, 2215 Garland Avenue, Nashville, TN 37232, USA
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Trypanosoma congolense Infections: Induced Nitric Oxide Inhibits Parasite Growth In Vivo. J Parasitol Res 2011; 2011:316067. [PMID: 21584233 PMCID: PMC3092548 DOI: 10.1155/2011/316067] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 02/07/2011] [Indexed: 11/17/2022] Open
Abstract
Wild-type (WT) C57BL/6 mice infected intraperitoneally with 5 × 10(6) Trypanosoma congolense survive for more than 30 days. C57BL/6 mice deficient in inducible nitric oxide synthase (iNOS(-/-)) and infected with 10(3) or 5 × 10(6) parasites do not control the parasitemia and survive for only 14 ± 7 or 6.8 ± 0.1 days, respectively. Bloodstream trypanosomes of iNOS(-/-) mice infected with 5 × 10(6)T. congolense had a significantly higher ratio of organisms in the S+G2+M phases of the cell cycle than trypanosomes in WT mice. We have reported that IgM anti-VSG-mediated phagocytosis of T. congolense by macrophages inhibits nitric oxide (NO) synthesis via CR3 (CD11b/CD18). Here, we show that during the first parasitemia, but not at later stages of infection, T. congolense-infected CD11b(-/-) mice produce more NO and have a significantly lower parasitemia than infected WT mice. We conclude that induced NO contributes to the control of parasitemia by inhibiting the growth of the trypanosomes.
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Amrouni D, Meiller A, Gautier-Sauvigné S, Piraud M, Bouteille B, Vincendeau P, Buguet A, Cespuglio R. Cerebral changes occurring in arginase and dimethylarginine dimethylaminohydrolase (DDAH) in a rat model of sleeping sickness. PLoS One 2011; 6:e16891. [PMID: 21408057 PMCID: PMC3052300 DOI: 10.1371/journal.pone.0016891] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 01/05/2011] [Indexed: 01/06/2023] Open
Abstract
Background Involvement of nitric oxide (NO) in the pathophysiology of human African trypanosomiasis (HAT) was analyzed in a HAT animal model (rat infected with Trypanosoma brucei brucei). With this model, it was previously reported that trypanosomes were capable of limiting trypanocidal properties carried by NO by decreasing its blood concentration. It was also observed that brain NO concentration, contrary to blood, increases throughout the infection process. The present approach analyses the brain impairments occurring in the regulations exerted by arginase and NG, NG–dimethylarginine dimethylaminohydrolase (DDAH) on NO Synthases (NOS). In this respect: (i) cerebral enzymatic activities, mRNA and protein expression of arginase and DDAH were determined; (ii) immunohistochemical distribution and morphometric parameters of cells expressing DDAH-1 and DDAH-2 isoforms were examined within the diencephalon; (iii) amino acid profiles relating to NOS/arginase/DDAH pathways were established. Methodology/Principal Findings Arginase and DDAH activities together with mRNA (RT-PCR) and protein (western-blot) expressions were determined in diencephalic brain structures of healthy or infected rats at various days post-infection (D5, D10, D16, D22). While arginase activity remained constant, that of DDAH increased at D10 (+65%) and D16 (+51%) in agreement with western-blot and amino acids data (liquid chromatography tandem-mass spectrometry). Only DDAH-2 isoform appeared to be up-regulated at the transcriptional level throughout the infection process. Immunohistochemical staining further revealed that DDAH-1 and DDAH-2 are contained within interneurons and neurons, respectively. Conclusion/Significance In the brain of infected animals, the lack of change observed in arginase activity indicates that polyamine production is not enhanced. Increases in DDAH-2 isoform may contribute to the overproduction of NO. These changes are at variance with those reported in the periphery. As a whole, the above processes may ensure additive protection against trypanosome entry into the brain, i.e., maintenance of NO trypanocidal pressure and limitation of polyamine production, necessary for trypanosome growth.
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MESH Headings
- Amidohydrolases/genetics
- Amidohydrolases/metabolism
- Amino Acids/blood
- Amino Acids/chemistry
- Animals
- Arginase/genetics
- Arginase/metabolism
- Biosynthetic Pathways
- Brain/enzymology
- Brain/parasitology
- Brain/pathology
- Disease Models, Animal
- Disease Progression
- Gene Expression Regulation, Enzymologic
- Humans
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Male
- Mass Spectrometry
- Models, Biological
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Trypanosoma brucei brucei
- Trypanosomiasis, African/blood
- Trypanosomiasis, African/enzymology
- Trypanosomiasis, African/parasitology
- Trypanosomiasis, African/pathology
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Affiliation(s)
- Donia Amrouni
- Université Claude Bernard Lyon 1, Université de Lyon, Faculté de Médecine, EA 4170 and Plateau NeuroChem, Lyon, France
| | - Anne Meiller
- Université Claude Bernard Lyon 1, Université de Lyon, Faculté de Médecine, EA 4170 and Plateau NeuroChem, Lyon, France
| | - Sabine Gautier-Sauvigné
- Université Claude Bernard Lyon 1, Université de Lyon, Faculté de Médecine, EA 4170 and Plateau NeuroChem, Lyon, France
| | - Monique Piraud
- Laboratoire des Maladies Héréditaires du Métabolisme, Centre de Biologie Est, Hospices Civils de Lyon, Lyon, France
| | - Bernard Bouteille
- Université de Limoges, Faculté de Médecine, EA 3174 and IFR 145 GEIST, Limoges, France
| | | | - Alain Buguet
- Université Claude Bernard Lyon 1, Université de Lyon, Faculté de Médecine, EA 4170 and Plateau NeuroChem, Lyon, France
| | - Raymond Cespuglio
- Université Claude Bernard Lyon 1, Université de Lyon, Faculté de Médecine, EA 4170 and Plateau NeuroChem, Lyon, France
- * E-mail:
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Lewis ND, Asim M, Barry DP, de Sablet T, Singh K, Piazuelo MB, Gobert AP, Chaturvedi R, Wilson KT. Immune evasion by Helicobacter pylori is mediated by induction of macrophage arginase II. THE JOURNAL OF IMMUNOLOGY 2011; 186:3632-41. [PMID: 21296975 DOI: 10.4049/jimmunol.1003431] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Helicobacter pylori infection persists for the life of the host due to the failure of the immune response to eradicate the bacterium. Determining how H. pylori escapes the immune response in its gastric niche is clinically important. We have demonstrated in vitro that macrophage NO production can kill H. pylori, but induction of macrophage arginase II (Arg2) inhibits inducible NO synthase (iNOS) translation, causes apoptosis, and restricts bacterial killing. Using a chronic H. pylori infection model, we determined whether Arg2 impairs host defense in vivo. In C57BL/6 mice, expression of Arg2, but not arginase I, was abundant and localized to gastric macrophages. Arg2(-/-) mice had increased histologic gastritis and decreased bacterial colonization compared with wild-type (WT) mice. Increased gastritis scores correlated with decreased colonization in individual Arg2(-/-) mice but not in WT mice. When mice infected with H. pylori were compared, Arg2(-/-) mice had more gastric macrophages, more of these cells were iNOS(+), and these cells expressed higher levels of iNOS protein, as determined by flow cytometry and immunofluorescence microscopy. There was enhanced nitrotyrosine staining in infected Arg2(-/-) versus WT mice, indicating increased NO generation. Infected Arg2(-/-) mice exhibited decreased macrophage apoptosis, as well as enhanced IFN-γ, IL-17a, and IL-12p40 expression, and reduced IL-10 levels consistent with a more vigorous Th1/Th17 response. These studies demonstrate that Arg2 contributes to the immune evasion of H. pylori by limiting macrophage iNOS protein expression and NO production, mediating macrophage apoptosis, and restraining proinflammatory cytokine responses.
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Affiliation(s)
- Nuruddeen D Lewis
- Division of Gastroenterology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Das P, Lahiri A, Lahiri A, Chakravortty D. Modulation of the arginase pathway in the context of microbial pathogenesis: a metabolic enzyme moonlighting as an immune modulator. PLoS Pathog 2010; 6:e1000899. [PMID: 20585552 PMCID: PMC2887468 DOI: 10.1371/journal.ppat.1000899] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Arginine is a crucial amino acid that serves to modulate the cellular immune response during infection. Arginine is also a common substrate for both inducible nitric oxide synthase (iNOS) and arginase. The generation of nitric oxide from arginine is responsible for efficient immune response and cytotoxicity of host cells to kill the invading pathogens. On the other hand, the conversion of arginine to ornithine and urea via the arginase pathway can support the growth of bacterial and parasitic pathogens. The competition between iNOS and arginase for arginine can thus contribute to the outcome of several parasitic and bacterial infections. There are two isoforms of vertebrate arginase, both of which catalyze the conversion of arginine to ornithine and urea, but they differ with regard to tissue distribution and subcellular localization. In the case of infection with Mycobacterium, Leishmania, Trypanosoma, Helicobacter, Schistosoma, and Salmonella spp., arginase isoforms have been shown to modulate the pathology of infection by various means. Despite the existence of a considerable body of evidence about mammalian arginine metabolism and its role in immunology, the critical choice to divert the host arginine pool by pathogenic organisms as a survival strategy is still a mystery in infection biology.
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Affiliation(s)
- Priyanka Das
- Center for Infectious Disease Research and Biosafety Laboratories, Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Amit Lahiri
- Center for Infectious Disease Research and Biosafety Laboratories, Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Ayan Lahiri
- Center for Infectious Disease Research and Biosafety Laboratories, Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Dipshikha Chakravortty
- Center for Infectious Disease Research and Biosafety Laboratories, Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
- * E-mail:
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Amrouni D, Gautier-Sauvigné S, Meiller A, Vincendeau P, Bouteille B, Buguet A, Cespuglio R. Cerebral and peripheral changes occurring in nitric oxide (NO) synthesis in a rat model of sleeping sickness: identification of brain iNOS expressing cells. PLoS One 2010; 5:e9211. [PMID: 20169057 PMCID: PMC2821905 DOI: 10.1371/journal.pone.0009211] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 01/26/2010] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The implication of nitric oxide (NO) in the development of human African trypanosomiasis (HAT) using an animal model, was examined. The manner by which the trypanocidal activity of NO is impaired in the periphery and in the brain of rats infected with Trypanosoma brucei brucei (T. b. brucei) was analyzed through: (i) the changes occurring in NO concentration in both peripheral (blood) and cerebral compartments; (ii) the activity of nNOS and iNOS enzymes; (iii) identification of the brain cell types in which the NO-pathways are particularly active during the time-course of the infection. METHODOLOGY/PRINCIPAL FINDINGS NO concentration (direct measures by voltammetry) was determined in central (brain) and peripheral (blood) compartments in healthy and infected animals at various days post-infection: D5, D10, D16 and D22. Opposite changes were observed in the two compartments. NO production increased in the brain (hypothalamus) from D10 (+32%) to D16 (+71%), but decreased in the blood from D10 (-22%) to D16 (-46%) and D22 (-60%). In parallel with NO measures, cerebral iNOS activity increased and peaked significantly at D16 (up to +700%). However, nNOS activity did not vary. Immunohistochemical staining confirmed iNOS activation in several brain regions, particularly in the hypothalamus. In peritoneal macrophages, iNOS activity decreased from D10 (-83%) to D16 (-65%) and D22 (-74%) similarly to circulating NO. CONCLUSION/SIGNIFICANCE The NO changes observed in our rat model were dependent on iNOS activity in both peripheral and central compartments. In the periphery, the NO production decrease may reflect an arginase-mediated synthesis of polyamines necessary to trypanosome growth. In the brain, the increased NO concentration may result from an enhanced activity of iNOS present in neurons and glial cells. It may be regarded as a marker of deleterious inflammatory reactions.
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Affiliation(s)
- Donia Amrouni
- University of Lyon, Faculty of Medicine, EA 4170 Laboratory of Free Radicals, Energy Substrates and Cerebral Physiopathology, & Neurochem platform, Lyon, France
| | - Sabine Gautier-Sauvigné
- University of Lyon, Faculty of Medicine, EA 4170 Laboratory of Free Radicals, Energy Substrates and Cerebral Physiopathology, & Neurochem platform, Lyon, France
| | - Anne Meiller
- University of Lyon, Faculty of Medicine, EA 4170 Laboratory of Free Radicals, Energy Substrates and Cerebral Physiopathology, & Neurochem platform, Lyon, France
| | - Philippe Vincendeau
- University of Bordeaux 2, EA 3677 Laboratory of Parasitology, Bordeaux, France
| | - Bernard Bouteille
- University of Limoges, EA 3174 Laboratory of Tropical and Compared Neuroepidemiology & IFR 145 GEIST, Faculty of Medicine, Limoges, France
| | - Alain Buguet
- University of Lyon, Faculty of Medicine, EA 4170 Laboratory of Free Radicals, Energy Substrates and Cerebral Physiopathology, & Neurochem platform, Lyon, France
| | - Raymond Cespuglio
- University of Lyon, Faculty of Medicine, EA 4170 Laboratory of Free Radicals, Energy Substrates and Cerebral Physiopathology, & Neurochem platform, Lyon, France
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Lewis ND, Asim M, Barry DP, Singh K, de Sablet T, Boucher JL, Gobert AP, Chaturvedi R, Wilson KT. Arginase II restricts host defense to Helicobacter pylori by attenuating inducible nitric oxide synthase translation in macrophages. THE JOURNAL OF IMMUNOLOGY 2010; 184:2572-82. [PMID: 20097867 DOI: 10.4049/jimmunol.0902436] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Helicobacter pylori infection of the stomach causes peptic ulcer disease and gastric cancer. Despite eliciting a vigorous immune response, the bacterium persists for the life of the host. An important antimicrobial mechanism is the production of NO derived from inducible NO synthase (iNOS). We have reported that macrophages can kill H. pylori in vitro by an NO-dependent mechanism, but supraphysiologic levels of the iNOS substrate l-arginine are required. Because H. pylori induces arginase activity in macrophages, we determined if this restricts NO generation by reducing l-arginine availability. Inhibition of arginase with S-(2-boronoethyl)-l-cysteine (BEC) significantly enhanced NO generation in H. pylori-stimulated RAW 264.7 macrophages by enhancing iNOS protein translation but not iNOS mRNA levels. This effect resulted in increased killing of H. pylori that was attenuated with an NO scavenger. In contrast, inhibition of arginase in macrophages activated by the colitis-inducing bacterium Citrobacter rodentium increased NO without affecting iNOS levels. H. pylori upregulated levels of arginase II (Arg2) mRNA and protein, which localized to mitochondria, whereas arginase I was not induced. Increased iNOS protein and NO levels were also demonstrated by small interfering RNA knockdown of Arg2 and in peritoneal macrophages from C57BL/6 Arg2(-/-) mice. In H. pylori-infected mice, treatment with BEC or deletion of Arg2 increased iNOS protein levels and NO generation in gastric macrophages, but treatment of Arg2(-/-) mice with BEC had no additional effect. These studies implicate Arg2 in the immune evasion of H. pylori by causing intracellular depletion of l-arginine and thus reduction of NO-dependent bactericidal activity.
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Affiliation(s)
- Nuruddeen D Lewis
- Division of Gastroenterology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37240, USA
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Nishimura K, Yanase T, Nakagawa H, Matsuo S, Ohnishi Y, Yamasaki S. Effect of polyamine-deficient chow on Trypanosoma brucei brucei infection in rats. J Parasitol 2010; 95:781-6. [PMID: 20049984 DOI: 10.1645/ge-1883.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Polyamines are essential for proliferation of Trypanosoma brucei brucei, and feeding rats polyamine-deficient chow (PDC) decreases their blood polyamine concentrations. Proliferation of T. b. brucei (IL-tat 1.4 strain) (IL) is not restrained within PDC-fed rats. However, symptoms of IL-infected rats such as anemia decrease by PDC feeding. We reported cytokine and nitric oxide (NO) production of T. b. gambiense (Wellcome strain [WS])-infected rats were affected by PDC feeding, and WS proliferation was restrained. Therefore, we investigated whether the change in production of cytokines and NO by PDC feeding affects IL proliferation and decreases symptoms in vivo. In IL-infected PDC-fed rats, NO, interleukin (IL)-12, and tumor necrosis factor-alpha production increased while interferon-gamma and IL-10 decreased compared to normal chow-fed rats. IL proliferation was restrained by NO production when it was co-cultured with spleen cells harvested from uninfected rats. In contrast, IL proliferation in infected rats was not changed by PDC feeding, although NO production was increased. The results suggest that changes in cytokines and NO production in IL-infected rats by PDC feeding have little influence on IL proliferation. However, they may serve to decrease symptoms.
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Affiliation(s)
- Kazuhiko Nishimura
- Laboratory of Infectious Diseases Control, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.
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Abstract
SUMMARYThe review addresses how infection withTrypanosoma bruceiaffects the development, survival and functions of B lymphocytes in mice. It discusses (1) the contributions of antibodies to trypanosome clearance from the bloodstream, (2) how B lymphocytes, the precursors of antibody producing plasma cells, interact with membrane form variable surface glycoprotein (VSG), i.e. with monovalent antigen that is free to diffuse within the lipid bilayer of the trypanosome plasma membrane and consequently can cross-link B cell antigen specific receptors by indirect processes only and (3) the extent and underlying causes of dysregulation of humoral immune responses in infected mice, focusing on the impact of wild type and GPI-PLC−/−trypanosomes on bone marrow and extramedullary B lymphopoiesis, B cell maturation and survival.
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Abstract
The enzyme arginase metabolizes L-arginine to L-ornithine and urea. Besides its fundamental role in the hepatic urea cycle, arginase is also expressed the immune system of mice and man. While significant interspecies differences exist regarding expression, subcellular localization and regulation of immune cell arginase, associated pathways of immunopathology are comparable between species. Arginase is induced in murine myeloid cells mainly by Th2 cytokines and inflammatory agents and participates in a variety of inflammatory diseases by down-regulation of nitric oxide synthesis, induction of fibrosis and tissue regeneration. In humans, arginase I is constitutively expressed in polymorphonuclear neutrophils and is liberated during inflammation. Myeloid cell arginase-mediated L-arginine depletion profoundly suppresses T cell immune responses and this has emerged as a fundamental mechanism of inflammation-associated immunosuppression. Pharmacological interference with L-arginine metabolism is a novel promising strategy in the treatment of cancer, autoimmunity or unwanted immune deviation.
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Affiliation(s)
- Markus Munder
- Department of Hematology, Oncology and Rheumatology, University Hospital Heidelberg, University of Heidelberg, Heidelberg, Germany.
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Gookin JL, Stauffer SH, Stone MR. Induction of arginase II by intestinal epithelium promotes the uptake of L-arginine from the lumen of Cryptosporidium parvum-infected porcine ileum. J Pediatr Gastroenterol Nutr 2008; 47:417-27. [PMID: 18852633 PMCID: PMC3685577 DOI: 10.1097/mpg.0b013e31816f6c02] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES To determine the specific transport system activities and expression of transporter genes responsible for uptake of L-arginine from the lumen of normal and Cryptosporidium parvum-infected neonatal porcine ileum and the influence of L-arginine catabolic pathways on L-arginine uptake. METHODS Intact sheets of ileal mucosa from control and C parvum-infected neonatal piglets were mounted in Ussing chambers and the uptake of 14C-L-arginine was determined under initial rate conditions and in the presence of transport system-selective inhibitors. Epithelial expression of L-arginine transporter genes was quantified by real-time reverse transcription polymerase chain reaction. L-Arginine catabolic enzyme expression was examined by immunoblotting epithelial lysates for arginase I and II. The role of intracellular catabolism in promoting the uptake of L-arginine was determined by pharmacological inhibition of nitric oxide synthase and arginase activities. RESULTS C parvum-infected ileum transported L-arginine at rates equivalent to uninfected epithelium despite profound villous atrophy. This was attributed to enhanced uptake of L-arginine by individual epithelial cells in the infection. There were no differences in L-arginine transport system activities (y(+) and B(0, +)) or level of transporter gene expression (CAT-1, CAT-2A, and ATB(0, +)) between uninfected and C parvum-infected epithelial cells. However, infected epithelia had induced expression of the L-arginine hydrolytic enzyme arginase II and lower concentrations of L-arginine. Furthermore, transport of L-arginine by the infected epithelium was significantly inhibited by pharmacological blockade of arginase. CONCLUSIONS Intracellular catabolism by arginase II, the induction of which has not been described previously for intestinal epithelium, facilitates uptake of L-arginine by infected epithelium using transport systems that do not differ from those of uninfected cells. Induction of arginase II may limit nitric oxide synthesis by competing with nitric oxide synthase for utilization of L-arginine or promote use of L-arginine for the synthesis of reparative polyamines.
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Affiliation(s)
- Jody L Gookin
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA.
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Nishimura K, Sakakibara S, Mitani K, Yamate J, Ohnishi Y, Yamasaki S. Inhibition of Interleukin-12 Production by Trypanosoma brucei in Rat Macrophages. J Parasitol 2008; 94:99-106. [DOI: 10.1645/ge-1322.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Nishimura K, Yagi M, Ohnishi Y, Yamasaki S. Cytokine and Nitric Oxide Production by Trypanosoma brucei Infection in Rats Fed Polyamine-Deficient Chow. J Parasitol 2008; 94:107-13. [DOI: 10.1645/ge-1267.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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45
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Mansfield JM, Paulnock DM. Genetic manipulation of African trypanosomes as a tool to dissect the immunobiology of infection. Parasite Immunol 2008; 30:245-53. [PMID: 18208450 DOI: 10.1111/j.1365-3024.2007.01003.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The variant surface glycoprotein (VSG) coat of African trypanosomes exhibits immunobiological functions distinct from its prominent role as a variant surface antigen. In order to address questions regarding immune stealth effects of VSG switch-variant coats, and the innate immune system activating effects of shed VSG substituents, several groups have genetically modified the ability of trypanosomes to express or release VSG during infection of the mammalian host. The role of mosaic surface coats expressed by VSG switch-variants (VSG double-expressors) in escaping early immune detection, and the role of VSG glycosylphosphatidylinositol (GPI) anchor substituents in regulating host immunity have been revealed, respectively, by stable co-expression of an exogenous VSG gene in trypanosomes expressing an endogenous VSG gene, and by knocking out the genetic locus for GPI-phospholipase C (PLC) that releases VSG from the membrane. Both approaches to genetic modification of African trypanosomes have suggested interesting and unexpected immunobiological effects associated with surface coat molecules.
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Affiliation(s)
- J M Mansfield
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Holzmuller P, Biron DG, Courtois P, Koffi M, Bras-Gonçalves R, Daulouède S, Solano P, Cuny G, Vincendeau P, Jamonneau V. Virulence and pathogenicity patterns of Trypanosoma brucei gambiense field isolates in experimentally infected mouse: differences in host immune response modulation by secretome and proteomics. Microbes Infect 2008; 10:79-86. [DOI: 10.1016/j.micinf.2007.10.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2007] [Revised: 09/19/2007] [Accepted: 10/11/2007] [Indexed: 10/22/2022]
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Storz JF, Baze M, Waite JL, Hoffmann FG, Opazo JC, Hayes JP. Complex signatures of selection and gene conversion in the duplicated globin genes of house mice. Genetics 2007; 177:481-500. [PMID: 17660536 PMCID: PMC2013706 DOI: 10.1534/genetics.107.078550] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Results of electrophoretic surveys have suggested that hemoglobin polymorphism may be maintained by balancing selection in natural populations of house mice, Mus musculus. Here we report a survey of nucleotide variation in the adult globin genes of house mice from South America. We surveyed nucleotide polymorphism in two closely linked alpha-globin paralogs and two closely linked beta-globin paralogs to test whether patterns of variation are consistent with a model of long-term balancing selection. Surprisingly high levels of nucleotide polymorphism at the two beta-globin paralogs were attributable to the segregation of two highly divergent haplotypes, Hbbs (which carries two identical beta-globin paralogs) and Hbbd (which carries two functionally divergent beta-globin paralogs). Interparalog gene conversion on the Hbbs haplotype has produced a highly unusual situation in which the two paralogs are more similar to one another than either one is to its allelic counterpart on the Hbbd haplotype. Levels of nucleotide polymorphism and linkage disequilibrium at the two beta-globin paralogs suggest a complex history of diversity-enhancing selection that may be responsible for long-term maintenance of alternative protein alleles. The alternative two-locus beta-globin haplotypes are associated with pronounced differences in intraerythrocyte glutathione and nitric oxide metabolism, suggesting a possible mechanism for selection on hemoglobin function.
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Affiliation(s)
- Jay F Storz
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA.
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Raes G, Beschin A, Ghassabeh GH, De Baetselier P. Alternatively activated macrophages in protozoan infections. Curr Opin Immunol 2007; 19:454-9. [PMID: 17628461 DOI: 10.1016/j.coi.2007.05.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Accepted: 05/21/2007] [Indexed: 11/25/2022]
Abstract
A type 1 cytokine-dependent pro-inflammatory response inducing classically activated macrophages is crucial for parasite control during protozoan infections but can also contribute to the development of immunopathological disease symptoms. Accumulating evidence indicates that interleukins 4, 13 and 10, transforming growth factor-beta, immune complexes and apoptotic cells elicited during these infections induce alternative activation states of macrophages, affecting disease outcome by, on the one hand, promoting parasite survival and proliferation and, on the other hand, limiting collateral tissue damage because of excessive type 1 inflammation. Thus, modulation of macrophage activation may be instrumental in allowing parasite persistence and long-term host survival.
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Affiliation(s)
- Geert Raes
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
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Villamil L, Gómez-León J, Gómez-Chiarri M. Role of nitric oxide in the defenses of Crassostrea virginica to experimental infection with the protozoan parasite Perkinsus marinus. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2007; 31:968-77. [PMID: 17368535 DOI: 10.1016/j.dci.2007.01.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2006] [Revised: 12/15/2006] [Accepted: 01/16/2007] [Indexed: 05/14/2023]
Abstract
We investigated the role of nitric oxide (NO) in the responses of the Eastern oyster, Crassostrea virginica, to the protozoan parasite Perkinsus marinus, causative agent of Dermo disease. P. marinus induced a slight but significant increase in NO production by oyster hemocytes in vitro, comparable to the increase induced by the immune stimulants phorbol myristrate acetate (PMA) and lipopolysaccharide (LPS). P. marinus also activated the NO response in oysters in vivo, as shown by induction of a protein reacting with a universal NO synthase (NOS) antibody in hemocytes and the presence of high levels of nitrite in plasma. Treatment of experimentally infected oysters with the NOS inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME) resulted in a transient decrease in NO levels in oyster plasma and a significant increase in the number of parasites at early time points after infection. The NO donor, S-nitroso-N-acetyl-penicillamine (SNAP) caused a significant inhibition in the proliferation of P. marinus cultured cells after 24 h of incubation. These results indicate that NO has a role in decreasing parasite loads at early time points after infection.
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Affiliation(s)
- Luisa Villamil
- Department of Fisheries, Animal, and Veterinary Science, University of Rhode Island, 23 Woodward Hall, Kingston, RI 02881, USA
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Vincendeau P, Bouteille B. Immunology and immunopathology of African trypanosomiasis. AN ACAD BRAS CIENC 2006; 78:645-65. [PMID: 17143404 DOI: 10.1590/s0001-37652006000400004] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2005] [Accepted: 10/05/2005] [Indexed: 11/21/2022] Open
Abstract
Major modifications of immune system have been observed in African trypanosomiasis. These immune reactions do not lead to protection and are also involved in immunopathology disorders. The major surface component (variable surface glycoprotein,VSG) is associated with escape to immune reactions, cytokine network dysfunctions and autoantibody production. Most of our knowledge result from experimental trypanosomiasis. Innate resistance elements have been characterised. In infected mice, VSG preferentially stimulates a Th 1-cell subset. A response of <FONT FACE=Symbol>gd</FONT> and CD8 T cells to trypanosome antigens was observed in trypanotolerant cattle. An increase in CD5 B cells, responsible for most serum IgM and production of autoantibodies has been noted in infected cattle. Macrophages play important roles in trypanosomiasis, in synergy with antibodies (phagocytosis) and by secreting various molecules (radicals, cytokines, prostaglandins,...). Trypanosomes are highly sensitive to TNF-alpha, reactive oxygen and nitrogen intermediates. TNF-alpha is also involved in cachexia. IFN-gamma acts as a parasite growth factor. These various elements contribute to immunosuppression. Trypanosomes have learnt to use immune mechanisms to its own profit. Recent data show the importance of alternative macrophage activation, including arginase induction. L-ornithine produced by host arginase is essential to parasite growth. All these data reflect the deep insight into the immune system realised by trypanosomes and might suggest interference therapeutic approaches.
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