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Palatella M, Guillaume SM, Linterman MA, Huehn J. The dark side of Tregs during aging. Front Immunol 2022; 13:940705. [PMID: 36016952 PMCID: PMC9398463 DOI: 10.3389/fimmu.2022.940705] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
In the last century, we have seen a dramatic rise in the number of older persons globally, a trend known as the grey (or silver) tsunami. People live markedly longer than their predecessors worldwide, due to remarkable changes in their lifestyle and in progresses made by modern medicine. However, the older we become, the more susceptible we are to a series of age-related pathologies, including infections, cancers, autoimmune diseases, and multi-morbidities. Therefore, a key challenge for our modern societies is how to cope with this fragile portion of the population, so that everybody could have the opportunity to live a long and healthy life. From a holistic point of view, aging results from the progressive decline of various systems. Among them, the distinctive age-dependent changes in the immune system contribute to the enhanced frailty of the elderly. One of these affects a population of lymphocytes, known as regulatory T cells (Tregs), as accumulating evidence suggest that there is a significant increase in the frequency of these cells in secondary lymphoid organs (SLOs) of aged animals. Although there are still discrepancies in the literature about modifications to their functional properties during aging, mounting evidence suggests a detrimental role for Tregs in the elderly in the context of bacterial and viral infections by suppressing immune responses against non-self-antigens. Interestingly, Tregs seem to also contribute to the reduced effectiveness of immunizations against many pathogens by limiting the production of vaccine-induced protective antibodies. In this review, we will analyze the current state of understandings about the role of Tregs in acute and chronic infections as well as in vaccination response in both humans and mice. Lastly, we provide an overview of current strategies for Treg modulation with potential future applications to improve the effectiveness of vaccines in older individuals.
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Affiliation(s)
- Martina Palatella
- Department Experimental Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | | | | | - Jochen Huehn
- Department Experimental Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
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2
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Chauhan R, Awasthi V, Thakur RS, Pande V, Chattopadhyay D, Das J. CD4 +ICOS +Foxp3 +: a sub-population of regulatory T cells contribute to malaria pathogenesis. Malar J 2022; 21:32. [PMID: 35109868 PMCID: PMC8812217 DOI: 10.1186/s12936-022-04055-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 01/19/2022] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Regulatory T cells are known to play a key role to counter balance the protective immune response and immune mediated pathology. However, the role of naturally occurring regulatory cells CD4+CD25+Foxp3+ in malaria infection during the disease pathogenesis is controversial. Beside this, ICOS molecule has been shown to be involved in the development and function of regulatory T cell enhance IL-10 production. Therefore, possible involvement of the ICOS dependent regulatory CD4+ICOS+Foxp3+ T cells in resistance/susceptibility during malaria parasite is explored in this study. METHODS 5 × 105 red blood cells infected with non-lethal and lethal parasites were inoculated in female Balb/c mice by intra-peritoneal injection. Infected or uninfected mice were sacrificed at early (3rd day post infection) and later stage (10th day post infection) of infection. Harvested cells were analysed by using flow cytometer and serum cytokine by Bioplex assay. RESULTS Thin blood films show that percentages of parasitaemia increases with disease progression in infections with the lethal malaria parasite and mice eventually die by day 14th post-infection. Whereas in case of non-lethal malaria parasite, parasitaemia goes down by 7th day post infection and gets cleared within 13th day. The number of CD4+ ICOS+ T cells increases in lethal infection with disease progression. Surprisingly, in non-lethal parasite, ICOS expression decreases after day 7th post infection as parasitaemia goes down. The frequency of CD4+ICOS+FoxP3+ Tregs was significantly higher in lethal parasitic infection as compared to the non-lethal parasite. The level of IL-12 cytokine was remarkably higher in non-lethal infection compared to the lethal infection. In contrast, the level of IL-10 cytokines was higher in lethal parasite infection compared to the non-lethal parasite. CONCLUSION Taken together, these data suggest that lethal parasite induce immunosuppressive environment, protecting from host immune responses and help the parasite to survive whereas non-lethal parasite leads to low frequencies of Treg cells seldom impede immune response that allow the parasite to get self-resolved.
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Affiliation(s)
- Rubika Chauhan
- Parasite-Host Biology, National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077, India
| | - Vikky Awasthi
- Parasite-Host Biology, National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077, India
| | - Reva Sharan Thakur
- Parasite-Host Biology, National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077, India
| | - Veena Pande
- Biotechnology Department, Kumaun University, Nainital, India
| | - Debprasad Chattopadhyay
- ICMR Virus Unit, ID and BG Hospital, Kolkata, 700010, India.,ICMR-National Institute of Traditional Medicine (NITM), Belagavi, 590010, India
| | - Jyoti Das
- Parasite-Host Biology, National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077, India.
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3
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Drewry LL, Harty JT. Balancing in a black box: Potential immunomodulatory roles for TGF-β signaling during blood-stage malaria. Virulence 2021; 11:159-169. [PMID: 32043415 PMCID: PMC7051139 DOI: 10.1080/21505594.2020.1726569] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Malarial disease caused by Plasmodium parasites challenges the mammalian immune system with a delicate balancing act. Robust inflammatory responses are required to control parasite replication within red blood cells, which if unchecked, can lead to severe anemia and fatality. However, the same inflammatory response that controls parasite replication is also associated with immunopathology and severe disease, as is exemplified by cerebral malaria. A robust literature has identified critical roles for innate, cellular, and humoral immune responses orchestrated by IFN-γ and TH1 type responses in controlling blood stage malarial disease. In contrast, TGF-β and IL-10 have been identified as important anti–inflammatory immunomodulators that help to limit inflammation and pathology during malaria. TGF-β is a pleiotropic cytokine, with the ability to exert a wide variety of context-dependent immunomodulatory roles. The specific mechanisms that allow TGF-β to protect against malarial pathology remain essentially unexplored and offer a promising avenue to dissect the most critical elements of immunomodulation in avoiding severe malaria. Here we discuss potential immunomodulatory roles for TGF-β during malaria in light of recent advances in our understanding of the role of Tregs during blood-stage malaria.
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Affiliation(s)
- Lisa L Drewry
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, USA
| | - John T Harty
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, USA.,Department of Pathology, University of Iowa, Iowa City, IA, USA.,Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, USA
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4
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Abstract
Immunity to malaria has been linked to the availability and function of helper CD4+ T cells, cytotoxic CD8+ T cells and γδ T cells that can respond to both the asymptomatic liver stage and the symptomatic blood stage of Plasmodium sp. infection. These T cell responses are also thought to be modulated by regulatory T cells. However, the precise mechanisms governing the development and function of Plasmodium-specific T cells and their capacity to form tissue-resident and long-lived memory populations are less well understood. The field has arrived at a point where the push for vaccines that exploit T cell-mediated immunity to malaria has made it imperative to define and reconcile the mechanisms that regulate the development and functions of Plasmodium-specific T cells. Here, we review our current understanding of the mechanisms by which T cell subsets orchestrate host resistance to Plasmodium infection on the basis of observational and mechanistic studies in humans, non-human primates and rodent models. We also examine the potential of new experimental strategies and human infection systems to inform a new generation of approaches to harness T cell responses against malaria.
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Fu Y, Ding Y, Wang Q, Zhu F, Tan Y, Lu X, Guo B, Zhang Q, Cao Y, Liu T, Cui L, Xu W. Blood-stage malaria parasites manipulate host innate immune responses through the induction of sFGL2. SCIENCE ADVANCES 2020; 6:eaay9269. [PMID: 32133407 PMCID: PMC7043914 DOI: 10.1126/sciadv.aay9269] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/05/2019] [Indexed: 06/10/2023]
Abstract
Malaria parasites suppress host immune responses to facilitate their survival, but the underlying mechanism remains elusive. Here, we found that blood-stage malaria parasites predominantly induced CD4+Foxp3+CD25+ regulatory T cells to release soluble fibrinogen-like protein 2 (sFGL2), which substantially enhanced the infection. This was attributed to the capacity of sFGL2 to inhibit macrophages from releasing monocyte chemoattractant protein-1 (MCP-1) and to sequentially reduce the recruitment of natural killer/natural killer T cells to the spleen and the production of interferon-γ. sFGL2 inhibited c-Jun N-terminal kinase phosphorylation in the Toll-like receptor 2 signaling pathway of macrophages dependent on FcγRIIB receptor to release MCP-1. Notably, sFGL2 were markedly elevated in the sera of patients with malaria, and recombinant FGL2 substantially suppressed Plasmodium falciparum from inducing macrophages to release MCP-1. Therefore, we highlight a previously unrecognized immune suppression strategy of malaria parasites and uncover the fundamental mechanism of sFGL2 to suppress host innate immune responses.
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Affiliation(s)
- Yong Fu
- Department of Pathogenic Biology, Army Medical University (The Third Military Medical University), Chongqing 400038, P.R. China
| | - Yan Ding
- Department of Pathogenic Biology, Army Medical University (The Third Military Medical University), Chongqing 400038, P.R. China
| | - Qinghui Wang
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, P.R. China
| | - Feng Zhu
- Department of Pathogenic Biology, Army Medical University (The Third Military Medical University), Chongqing 400038, P.R. China
| | - Yulong Tan
- Department of Tropical Medicine, Army Medical University (The Third Military Medical University), Chongqing 400038, P.R. China
| | - Xiao Lu
- Department of Pathogenic Biology, Army Medical University (The Third Military Medical University), Chongqing 400038, P.R. China
| | - Bo Guo
- Department of Pathogenic Biology, Army Medical University (The Third Military Medical University), Chongqing 400038, P.R. China
| | - Qingfeng Zhang
- Research Center for Translational Medicine, Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, P.R. China
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, P.R. China
| | - Taiping Liu
- Department of Pathogenic Biology, Army Medical University (The Third Military Medical University), Chongqing 400038, P.R. China
| | - Liwang Cui
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Wenyue Xu
- Department of Pathogenic Biology, Army Medical University (The Third Military Medical University), Chongqing 400038, P.R. China
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Hose M, Günther A, Abberger H, Begum S, Korencak M, Becker KA, Buer J, Westendorf AM, Hansen W. T Cell-Specific Overexpression of Acid Sphingomyelinase Results in Elevated T Cell Activation and Reduced Parasitemia During Plasmodium yoelii Infection. Front Immunol 2019; 10:1225. [PMID: 31214184 PMCID: PMC6554418 DOI: 10.3389/fimmu.2019.01225] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 05/14/2019] [Indexed: 12/31/2022] Open
Abstract
The enzyme acid sphingomyelinase (ASM) hydrolyzes sphingomyelin to ceramide and is thereby involved in several cellular processes such as differentiation, proliferation, and apoptosis in different cell types. However, the function of ASM in T cells is still not well characterized. Here, we used T cell-specific ASM overexpressing mice (t-ASM/CD4cre) to clarify the impact of cell-intrinsic ASM activity on T cell function in vitro and in vivo. We showed that t-ASM/CD4cre mice exhibit decreased frequencies of Foxp3+ T regulatory cells (Tregs) within the spleen. Enforced T cell-specific ASM expression resulted in less efficient induction of Tregs and promoted differentiation of CD4+CD25− naïve T cells into IFN-γ producing Th1 cells in vitro. Further analysis revealed that ASM-overexpressing T cells from t-ASM/CD4cre mice show elevated T cell receptor (TCR) signaling activity accompanied with increased proliferation upon stimulation in vitro. Plasmodium yoelii infection of t-ASM/CD4cre mice resulted in enhanced T cell activation and was associated with reduced parasitemia in comparison to infected control mice. Hence, our results provide evidence that ASM activity modulates T cell function in vitro and in vivo.
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Affiliation(s)
- Matthias Hose
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Anne Günther
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Hanna Abberger
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Salina Begum
- Institute of Molecular Biology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Marek Korencak
- Institute for HIV Research, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Katrin A Becker
- Institute of Molecular Biology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Jan Buer
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Astrid M Westendorf
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Wiebke Hansen
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
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Okeke EB, Uzonna JE. The Pivotal Role of Regulatory T Cells in the Regulation of Innate Immune Cells. Front Immunol 2019; 10:680. [PMID: 31024539 PMCID: PMC6465517 DOI: 10.3389/fimmu.2019.00680] [Citation(s) in RCA: 144] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 03/12/2019] [Indexed: 12/11/2022] Open
Abstract
The distinction between innate and adaptive immunity is one of the basic tenets of immunology. The co-operation between these two arms of the immune system is a major determinant of the resistance or susceptibility of the host following pathogen invasion. Hence, this interactive co-operation between cells of the innate and adaptive immunity is of significant interest to immunologists. The sub-population of CD4+ T cells with regulatory phenotype (regulatory T cells; Tregs), which constitute a part of the adaptive immune system, have been widely implicated in the regulation of the immune system and maintenance of immune homeostasis. In the last two decades, there has been an explosion in research describing the role of Tregs and their relevance in several immunopathologies ranging from inflammation to cancer. The majority of these studies focus on the role of Tregs on the cells of the adaptive immune system. Recently, there is significant interest in the role of Tregs on cells of the innate immune system. In this review, we examine the literature on the role of Tregs in immunology. Specifically, we focus on the emerging knowledge of Treg interaction with dendritic cells, macrophages, neutrophils, and γδ T cells. We highlight this interaction as an important link between innate and adaptive immune systems which also indicate the far-reaching role of Tregs in the regulation of immune responses and maintenance of self-tolerance and immune homeostasis.
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Affiliation(s)
- Emeka B Okeke
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Jude E Uzonna
- Department of Immunology, Faculty of Medicine, University of Manitoba, Winnipeg, MB, Canada
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8
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Ssemaganda A, Giddam AK, Zaman M, Skwarczynski M, Toth I, Stanisic DI, Good MF. Induction of Plasmodium-Specific Immune Responses Using Liposome-Based Vaccines. Front Immunol 2019; 10:135. [PMID: 30774635 PMCID: PMC6367261 DOI: 10.3389/fimmu.2019.00135] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 01/16/2019] [Indexed: 12/30/2022] Open
Abstract
In the development of vaccines, the ability to initiate both innate and subsequent adaptive immune responses need to be considered. Live attenuated vaccines achieve this naturally, while inactivated and sub-unit vaccines generally require additional help provided through delivery systems and/or adjuvants. Liposomes present an attractive adjuvant/delivery system for antigens. Here, we review the key aspects of immunity against Plasmodium parasites, liposome design considerations and their current application in the development of a malaria vaccine.
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Affiliation(s)
| | | | - Mehfuz Zaman
- Institute for Glycomics, Griffith University, Southport, QLD, Australia
| | - Mariusz Skwarczynski
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Istvan Toth
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
- School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | | | - Michael F. Good
- Institute for Glycomics, Griffith University, Southport, QLD, Australia
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9
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Frimpong A, Kusi KA, Tornyigah B, Ofori MF, Ndifon W. Characterization of T cell activation and regulation in children with asymptomatic Plasmodium falciparum infection. Malar J 2018; 17:263. [PMID: 30005684 PMCID: PMC6045887 DOI: 10.1186/s12936-018-2410-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/07/2018] [Indexed: 02/08/2023] Open
Abstract
Background Asymptomatic Plasmodium infections are characterized by the absence of clinical disease and the ability to restrict parasite replication. Increasing levels of regulatory T cells (Tregs) in Plasmodium falciparum infections have been associated with the risk of developing clinical disease, suggesting that individuals with asymptomatic infections may have reduced Treg frequency. However, the relationship between Tregs, cellular activation and parasite control in asymptomatic malaria remains unclear. Methods In a cross-sectional study, the levels of Tregs and other T cell activation phenotypes were compared using flow cytometry in symptomatic, asymptomatic and uninfected children before and after stimulation with infected red blood cell lysates (iRBCs). In addition, the association between these T cell phenotypes and parasitaemia were investigated. Results In children with asymptomatic infections, levels of Tregs and activated T cells were comparable to those in healthy controls but significantly lower than those in symptomatic children. After iRBC stimulation, levels of Tregs remained lower for asymptomatic versus symptomatic children. In contrast, levels of activated T cells were higher for asymptomatic children. Strikingly, the pre-stimulation levels of two T cell activation phenotypes (CD8+CD69+ and CD8+CD25+CD69+) and the post-stimulation levels of two regulatory phenotypes (CD4+CD25+Foxp3+ and CD8+CD25+Foxp3+) were significantly positively correlated with and explained 68% of the individual variation in parasitaemia. A machine-learning model based on levels of these four phenotypes accurately distinguished between asymptomatic and symptomatic children (sensitivity = 86%, specificity = 94%), suggesting that these phenotypes govern the observed variation in disease status. Conclusion Compared to symptomatic P. falciparum infections, in children asymptomatic infections are characterized by lower levels of Tregs and activated T cells, which are associated with lower parasitaemia. The results indicate that T cell regulatory and activation phenotypes govern both parasitaemia and disease status in paediatric malaria in the studied sub-Saharan African population. Electronic supplementary material The online version of this article (10.1186/s12936-018-2410-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Augustina Frimpong
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, P. O. Box LG 54, Accra, Ghana. .,Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O. Box LG 581, Accra, Ghana. .,African Institute for Mathematical Sciences, P.O. Box DL 676, Cape-Coast, Ghana.
| | - Kwadwo Asamoah Kusi
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, P. O. Box LG 54, Accra, Ghana.,Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O. Box LG 581, Accra, Ghana
| | - Bernard Tornyigah
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O. Box LG 581, Accra, Ghana
| | - Michael Fokuo Ofori
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, P. O. Box LG 54, Accra, Ghana.,Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O. Box LG 581, Accra, Ghana
| | - Wilfred Ndifon
- African Institute for Mathematical Sciences, P.O. Box DL 676, Cape-Coast, Ghana. .,African Institute for Mathematical Sciences, University of Stellenbosch, 7 Melrose Rd, Muizenberg, Cape Town, 7945, South Africa.
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Soon MSF, Haque A. Recent Insights into CD4+Th Cell Differentiation in Malaria. THE JOURNAL OF IMMUNOLOGY 2018; 200:1965-1975. [DOI: 10.4049/jimmunol.1701316] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/08/2018] [Indexed: 02/06/2023]
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Ueffing K, Abberger H, Westendorf AM, Matuschewski K, Buer J, Hansen W. Conventional CD11c high Dendritic Cells Are Important for T Cell Priming during the Initial Phase of Plasmodium yoelii Infection, but Are Dispensable at Later Time Points. Front Immunol 2017; 8:1333. [PMID: 29085373 PMCID: PMC5650681 DOI: 10.3389/fimmu.2017.01333] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 10/02/2017] [Indexed: 12/20/2022] Open
Abstract
Dendritic cells (DCs) are highly specialized antigen-presenting cells that orchestrate adaptive immune responses to pathogens. During malaria infection pro- and anti-inflammatory T cell responses have to be tightly balanced to ensure parasite clearance without induction of severe immune pathologies. However, the precise role of CD11chigh DCs in this process is still discussed controversially. Here, we demonstrate that long-term depletion of conventional CD11chigh DCs in Plasmodium yoelii (P. yoelii)-infected diphtheria toxin (DT)-treated RosaiDTR/CD11c-cre mice interferes with the activation of CD8+ and CD4+ T cells as well as CD4+Foxp3+ regulatory T cells at early time points during infection. Moreover, systemic levels of the pro-inflammatory cytokines IFN-γ and TNF-α were decreased in P. yoelii-infected mice deficient for CD11chigh DCs compared to infected RosaiDTR controls. To further elucidate the importance of CD11chigh DCs during the later phase of infection, we treated RosaiDTR/CD11c-cre and control mice with DT only from day 4 of P. yoelii infection onward. Strikingly, this approach had no impact on the activation and IFN-γ production of CD4+ and CD8+ effector T cells. These results indicate that CD11chigh DCs play a crucial role in eliciting effector T cell responses during the initial phase, but are dispensable during ongoing infection with P. yoelii.
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Affiliation(s)
- Kristina Ueffing
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Hanna Abberger
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Astrid M Westendorf
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Kai Matuschewski
- Molecular Parasitology, Institute of Biology, Humboldt University of Berlin, Berlin, Germany
| | - Jan Buer
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Wiebke Hansen
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
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12
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Regulatory T cells impede acute and long-term immunity to blood-stage malaria through CTLA-4. Nat Med 2017; 23:1220-1225. [PMID: 28892065 DOI: 10.1038/nm.4395] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/05/2017] [Indexed: 02/07/2023]
Abstract
Malaria, caused by the protozoan Plasmodium, is a devastating mosquito-borne disease with the potential to affect nearly half the world's population. Despite mounting substantial T and B cell responses, humans fail to efficiently control blood-stage malaria or develop sterilizing immunity to reinfections. Although forkhead box P3 (FOXP3)+CD4+ regulatory T (Treg) cells form a part of these responses, their influence remains disputed and their mode of action is unknown. Here we show that Treg cells expand in both humans and mice in blood-stage malaria and interfere with conventional T helper cell responses and follicular T helper (TFH)-B cell interactions in germinal centers. Mechanistically, Treg cells function in a critical temporal window to impede protective immunity through cytotoxic-T-lymphocyte-associated protein-4 (CTLA-4). Targeting Treg cells or CTLA-4 in this precise window accelerated parasite clearance and generated species-transcending immunity to blood-stage malaria in mice. Our study uncovers a critical mechanism of immunosuppression associated with blood-stage malaria that delays parasite clearance and prevents development of potent adaptive immunity to reinfection. These data also reveal a temporally discrete and potentially therapeutically amenable functional role for Treg cells and CTLA-4 in limiting antimalarial immunity.
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13
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Keswani T, Sarkar S, Sengupta A, Bhattacharyya A. Role of TGF-β and IL-6 in dendritic cells, Treg and Th17 mediated immune response during experimental cerebral malaria. Cytokine 2016; 88:154-166. [DOI: 10.1016/j.cyto.2016.08.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 07/31/2016] [Accepted: 08/30/2016] [Indexed: 12/14/2022]
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Abstract
Parasites of the genus Plasmodium have a complex life cycle. They alternate between their final mosquito host and their intermediate hosts. The parasite can be either extra- or intracellular, depending on the stage of development. By modifying their shape, motility, and metabolic requirements, the parasite adapts to the different environments in their different hosts. The parasite has evolved to escape the multiple immune mechanisms in the host that try to block parasite development at the different stages of their development. In this article, we describe the mechanisms reported thus far that allow the Plasmodium parasite to evade innate and adaptive immune responses.
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Affiliation(s)
- Laurent Rénia
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Yun Shan Goh
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
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15
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Kaewraemruaen C, Sermswan RW, Wongratanacheewin S. Induction of regulatory T cells by Opisthorchis viverrini. Parasite Immunol 2016; 38:688-697. [PMID: 27552546 DOI: 10.1111/pim.12358] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 08/19/2016] [Indexed: 01/04/2023]
Abstract
Opisthorchis viverrini causes public health problems in South-East Asia. Recently, TGF-β and IL-10 have been reported to increase in O. viverrini-infected hamsters but the sources of these cytokines are still unknown. In this study, the CD4+ T cells in infected hamsters were investigated. It was demonstrated that IL-4+ CD4+ T cells were significantly increased in hamster spleens and mesenteric lymph nodes (MLNs) during chronic infection. Interestingly, IL-10+ CD4+ T cells were also discovered at a significant level while Treg (T regulatory)-like TGF- β+ CD4+ T cells were in MLNs of infected hamsters. Moreover, the CD4+ CD25+ Foxp3+ Treg cell response was significantly found both in spleens and MLNs in infected hamsters. The findings were then confirmed by development of T-cell clones against crude somatic antigens (CSAg) in immunized BALB/c mice. Five clones named TCC21, TCC23, TCC35, TCC41 and TCC108 were established. The TCC21 was found to be the TGF-β+ CD4+ while TCC35, TCC41 and TCC108 were IL-4+ CD4+ and TCC23 was IFN-γ+ CD4+ . This TGF-β+ CD4+ T clone showed an inhibitory function in vitro in mononuclear cell proliferation via TGF-β-mediated mechanisms. This study indicated that O. viverrini-infected hamsters could induce TGF-β+ CD4+ Treg-like cells. The CSAg-specific Tregs secreted high TGF-β, and limited immune cell proliferation.
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Affiliation(s)
- C Kaewraemruaen
- Department of Microbiology, Khon Kaen University, Khon Kaen, Thailand.,Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand
| | - R W Sermswan
- Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand.,Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - S Wongratanacheewin
- Department of Microbiology, Khon Kaen University, Khon Kaen, Thailand. .,Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand.
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16
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Van Braeckel-Budimir N, Kurup SP, Harty JT. Regulatory issues in immunity to liver and blood-stage malaria. Curr Opin Immunol 2016; 42:91-97. [PMID: 27351448 DOI: 10.1016/j.coi.2016.06.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 06/10/2016] [Accepted: 06/15/2016] [Indexed: 02/01/2023]
Abstract
T cells play a major role in control of both blood and liver stage of plasmodium infection. While immunization with certain attenuated whole-parasite vaccines that are attenuated at the liver stage of the infection induces protective T cell responses, even multiple exposures to natural infection in endemic areas do not lead to stable T cell memory or humoral immunity and sterilizing protection. One of the key differences between vaccination and natural exposure is the absence of blood stage during vaccination. Here we will discuss possible immunoregulatory strategies employed by blood stage of malaria leading to generation of severely compromised T cell and humoral immune responses and subsequent lack of sterilizing immunity.
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Affiliation(s)
| | - Samarchith P Kurup
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
| | - John T Harty
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA; Department of Pathology, University of Iowa, Iowa City, IA 52242, USA; Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA 52242, USA.
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17
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Bijker EM, Schats R, Visser LG, Sauerwein RW, Scholzen A. Ex vivo lymphocyte phenotyping during Plasmodium falciparum sporozoite immunization in humans. Parasite Immunol 2016; 37:590-8. [PMID: 26363409 DOI: 10.1111/pim.12276] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 09/01/2015] [Indexed: 12/29/2022]
Abstract
Immunization of malaria-naïve volunteers under chemoprophylaxis with Plasmodium falciparum sporozoites (CPS) efficiently and reproducibly induces sterile protection and thus constitutes an excellent model to study protective immune responses against malaria. Here, we performed the first longitudinal assessment of lymphocyte activation and differentiation kinetics during sporozoite immunization in 15 volunteers by ex vivo lymphocyte flow cytometry analysis. Both CD4 and CD8 T cells as well as γδT cells, NK cells and CD3+ CD56+ cells showed increased activation and proliferation following immunization. Transient induction of the transcription factor T-bet and the cytotoxic molecule granzyme B indicated a role of Th1 responses and cytotoxic T cells in CPS-induced immunity. The absolute number of γδT cells as well as the proportion of granzyme B-containing γδT cells showed a significant and sustained increase. Regulatory T-cell (Treg) proliferation was significantly higher after the second immunization in subjects subsequently not protected against challenge infection. These findings indicate an important role for γδT cells, Th1 and cytotoxic responses in whole sporozoite immunization with a possibly suppressive role of Tregs.
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Affiliation(s)
- E M Bijker
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - R Schats
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - L G Visser
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - R W Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - A Scholzen
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
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18
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Okeke EB, Uzonna JE. In Search of a Cure for Sepsis: Taming the Monster in Critical Care Medicine. J Innate Immun 2016; 8:156-70. [PMID: 26771196 DOI: 10.1159/000442469] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 11/16/2015] [Indexed: 12/21/2022] Open
Abstract
In spite of over half a century of research, sepsis still constitutes a major problem in health care delivery. Although advances in research have significantly increased our knowledge of the pathogenesis of sepsis and resulted in better prognosis and improved survival outcome, sepsis still remains a major challenge in modern medicine with an increase in occurrence predicted and a huge socioeconomic burden. It is generally accepted that sepsis is due to an initial hyperinflammatory response. However, numerous efforts aimed at targeting the proinflammatory cytokine network have been largely unsuccessful and the search for novel potential therapeutic targets continues. Recent studies provide compelling evidence that dysregulated anti-inflammatory responses may also contribute to sepsis mortality. Our previous studies on the role of regulatory T cells and phosphoinositide 3-kinases in sepsis highlight immunological approaches that could be explored for sepsis therapy. In this article, we review the current and emerging concepts in sepsis, highlight novel potential therapeutic targets and immunological approaches for sepsis treatment and propose a biphasic treatment approach for management of the condition.
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Affiliation(s)
- Emeka B Okeke
- Department of Immunology, Faculty of Medicine, University of Manitoba, Winnipeg, Man., Canada
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19
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Abstract
Naturally acquired immunity to the blood-stage of the malaria parasite develops slowly in areas of high endemicity, but is not sterilizing. It manifests as a reduction in parasite density and clinical symptoms. Immunity as a result of blood-stage vaccination has not yet been achieved in humans, although there are many animal models where vaccination has been successful. The development of a blood-stage vaccine has been complicated by a number of factors including limited knowledge of human-parasite interactions and which antigens and immune responses are critical for protection. Opinion is divided as to whether this vaccine should aim to accelerate the acquisition of responses acquired following natural exposure, or whether it should induce a different response. Animal and experimental human models suggest that cell-mediated immune responses can control parasite growth, but these responses can also contribute to significant immunopathology if unregulated. They are largely ignored in most blood-stage malaria vaccine development strategies. Here, we discuss key observations relating to cell-mediated immune responses in the context of experimental human systems and field studies involving naturally exposed individuals and how this may inform the development of a blood-stage malaria vaccine.
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20
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Deroost K, Pham TT, Opdenakker G, Van den Steen PE. The immunological balance between host and parasite in malaria. FEMS Microbiol Rev 2015; 40:208-57. [PMID: 26657789 DOI: 10.1093/femsre/fuv046] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2015] [Indexed: 12/16/2022] Open
Abstract
Coevolution of humans and malaria parasites has generated an intricate balance between the immune system of the host and virulence factors of the parasite, equilibrating maximal parasite transmission with limited host damage. Focusing on the blood stage of the disease, we discuss how the balance between anti-parasite immunity versus immunomodulatory and evasion mechanisms of the parasite may result in parasite clearance or chronic infection without major symptoms, whereas imbalances characterized by excessive parasite growth, exaggerated immune reactions or a combination of both cause severe pathology and death, which is detrimental for both parasite and host. A thorough understanding of the immunological balance of malaria and its relation to other physiological balances in the body is of crucial importance for developing effective interventions to reduce malaria-related morbidity and to diminish fatal outcomes due to severe complications. Therefore, we discuss in this review the detailed mechanisms of anti-malarial immunity, parasite virulence factors including immune evasion mechanisms and pathogenesis. Furthermore, we propose a comprehensive classification of malaria complications according to the different types of imbalances.
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Affiliation(s)
- Katrien Deroost
- Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000 Leuven, Belgium The Francis Crick Institute, Mill Hill Laboratory, London, NW71AA, UK
| | - Thao-Thy Pham
- Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000 Leuven, Belgium
| | - Ghislain Opdenakker
- Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000 Leuven, Belgium
| | - Philippe E Van den Steen
- Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000 Leuven, Belgium
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21
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Howland SW, Claser C, Poh CM, Gun SY, Rénia L. Pathogenic CD8+ T cells in experimental cerebral malaria. Semin Immunopathol 2015; 37:221-31. [PMID: 25772948 DOI: 10.1007/s00281-015-0476-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 03/01/2015] [Indexed: 11/26/2022]
Abstract
Cerebral malaria (CM) is one the major complications occurring during malaria infection. The mechanisms leading to this syndrome are still not completely understood. Although it is clear that parasite sequestration is the key initiation factor, the downstream pathological processes are still highly debated. The experimental cerebral malaria (ECM) model, in which susceptible mice are infected with Plasmodium berghei ANKA, has led to the identification of CD8(+) T cells as the major mediator of ECM death. In this review, we discuss the recent advances and future developments in the understanding of the role of CD8(+) T cells in CM.
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Affiliation(s)
- Shanshan Wu Howland
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
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22
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An increase in CD3+CD4+CD25+ regulatory T cells after administration of umbilical cord-derived mesenchymal stem cells during sepsis. PLoS One 2014; 9:e110338. [PMID: 25337817 PMCID: PMC4206342 DOI: 10.1371/journal.pone.0110338] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 09/20/2014] [Indexed: 12/13/2022] Open
Abstract
Sepsis remains an important cause of death worldwide, and vigorous immune responses during sepsis could be beneficial for bacterial clearance but at the price of collateral damage to self tissues. Mesenchymal stem cells (MSCs) have been found to modulate the immune system and attenuate sepsis. In the present study, MSCs derived from bone marrow and umbilical cord were used and compared. With a cecal ligation and puncture (CLP) model, the mechanisms of MSC-mediated immunoregulation during sepsis were studied by determining the changes of circulating inflammation-associated cytokine profiles and peripheral blood mononuclear cells 18 hours after CLP-induced sepsis. In vitro, bone marrow-derived MSCs (BMMSCs) and umbilical cord-derived MSCs (UCMSCs) showed a similar morphology and surface marker expression. UCMSCs had stronger potential for osteogenesis but lower for adipogenesis than BMMSCs. Compared with rats receiving PBS only after CLP, the percentage of circulating CD3+CD4+CD25+ regulatory T (Treg) cells and the ratio of Treg cells/T cells were elevated significantly in rats receiving MSCs. Further experiment regarding Treg cell function demonstrated that the immunosuppressive capacity of Treg cells from rats with CLP-induced sepsis was decreased, but could be restored by administration of MSCs. Compared with rats receiving PBS only after CLP, serum levels of interleukin-6 and tumor necrosis factor-α were significantly lower in rats receiving MSCs after CLP. There were no differences between BMMSCs and UCMSCs. In summary, this work provides the first in vivo evidence that administering BMMSCs or UCMSCs to rats with CLP-induced sepsis could increase circulating CD3+CD4+CD25+ Treg cells and Treg cells/T cells ratio, enhance Treg cell suppressive function, and decrease serum levels of interleukin-6 and tumor necrosis factor-α, suggesting the immunomodulatory association of Treg cells and MSCs during sepsis.
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23
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Okeke EB, Okwor I, Uzonna JE. Regulatory T cells restrain CD4+ T cells from causing unregulated immune activation and hypersensitivity to lipopolysaccharide challenge. THE JOURNAL OF IMMUNOLOGY 2014; 193:655-62. [PMID: 24943218 DOI: 10.4049/jimmunol.1303064] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Regulatory T cells (Tregs) are essential for maintenance of peripheral tolerance, and defects in Treg function have been linked to several autoimmune diseases. We previously reported that depletion of Tregs resulted in mortality to an otherwise nonlethal dose of LPS or Escherichia coli challenge. In this study, we investigated the mechanism by which Treg depletion leads to enhanced susceptibility to LPS. Using different murine lymphocyte gene knockout models, we show that the enhanced sensitivity to LPS following Treg depletion is mediated by T cells. SCID or RAG1-deficient mice, which lack T and B cells, do not show enhanced susceptibility to LPS. However, reconstitution of SCID mice with wild-type CD4(+) T cells restored Treg depletion-induced sensitivity to LPS. This CD4(+) T cell-mediated hypersensitivity to LPS challenge in the absence of Tregs was also observed upon reconstitution of SCID mice with CD4(+) T cells from CD25 knockout mice (which lack functional Tregs). Additionally, depletion of Tregs leads to increased CD4(+) T cell proliferation and proinflammatory cytokine production in response to LPS challenge. Some CD4(+) T cells express TLR4, and pretreatment of CD4(+) T cells with LPS dramatically enhanced their ability to induce inflammatory cytokine production by macrophages. Collectively, our results indicate that in the absence of functional Tregs, CD4(+) T cells are pathologic and contribute to exaggerated immune activation that is detrimental for survival in LPS-induced acute inflammation. Our data also provide evidence for direct activation of CD4(+) T cells by LPS through TLR4.
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Affiliation(s)
- Emeka B Okeke
- Department of Immunology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba R3E 0T5, Canada; and
| | - Ifeoma Okwor
- Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba R3E 0T5, Canada
| | - Jude E Uzonna
- Department of Immunology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba R3E 0T5, Canada; and Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba R3E 0T5, Canada
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24
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Keswani T, Bhattacharyya A. Differential role of T regulatory and Th17 in Swiss mice infected with Plasmodium berghei ANKA and Plasmodium yoelii. Exp Parasitol 2014; 141:82-92. [PMID: 24675415 DOI: 10.1016/j.exppara.2014.03.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 01/21/2014] [Accepted: 03/04/2014] [Indexed: 12/31/2022]
Abstract
The outcome of malaria infection is determined, in part, by the balance of pro-inflammatory and regulatory immune responses. Host immune responses in disease including malaria are finely regulated by the opposing effects of Th17 and T regulatory (Treg) cells. Here we have examined the role of Treg cells and Th17 cells during malaria infection and find that low levels of Treg cells possibly influence the outcome of infections with the lethal strain of Plasmodium berghei ANKA (PbA). In contrast, high level of Treg cells may influence the outcome of nonlethal Plasmodium yoelii NXL (P. yoelii) infections. We observed decreased expressions of key regulators of Treg inductions-TGF-β, CD4IL-2 and IL-10 during PbA infection, whereas their expression remains high during P. yoelii infection. On the other hand TNF-α, IL-6, IFN-γ and IL-23 expression is high during PbA infection and lower during P. yoelii infection. Thus, results from this study suggest that the differential expression of Treg and Th17 might have a key role on host pathogenesis during malaria infection. The high level of IL-6 and low level of TGF-β may composite of the advantaged local microenvironment for the production of Th17 cells in the spleen of the PBA infected mice and vice verse during nonlethal P. yoelii.
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Affiliation(s)
- Tarun Keswani
- Immunology Laboratory, Department of Zoology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata 700019, West Bengal, India.
| | - Arindam Bhattacharyya
- Immunology Laboratory, Department of Zoology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata 700019, West Bengal, India.
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25
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Zhu YG, Hao Q, Monsel A, Feng XM, Lee JW. Adult stem cells for acute lung injury: remaining questions and concerns. Respirology 2014; 18:744-56. [PMID: 23578018 DOI: 10.1111/resp.12093] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 04/02/2013] [Indexed: 12/22/2022]
Abstract
Acute lung injury (ALI) or acute respiratory distress syndrome remains a major cause of morbidity and mortality in hospitalized patients. The pathophysiology of ALI involves complex interactions between the inciting event, such as pneumonia, sepsis or aspiration, and the host immune response resulting in lung protein permeability, impaired resolution of pulmonary oedema, an intense inflammatory response in the injured alveolus and hypoxemia. In multiple preclinical studies, adult stem cells have been shown to be therapeutic due to both the ability to mitigate injury and inflammation through paracrine mechanisms and perhaps to regenerate tissue by virtue of their multi-potency. These characteristics have stimulated intensive research efforts to explore the possibility of using stem or progenitor cells for the treatment of lung injury. A variety of stem or progenitor cells have been isolated, characterized and tested experimentally in preclinical animal models of ALI. However, questions remain concerning the optimal dose, route and the adult stem or progenitor cell to use. Here, the current mechanisms underlying the therapeutic effect of stem cells in ALI as well as the questions that will arise as clinical trials for ALI are planned are reviewed.
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Affiliation(s)
- Ying-Gang Zhu
- Department of Pulmonary Medicine, Huadong Hospital, Fudan University, Shanghai, China
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26
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Liver accumulation of Plasmodium chabaudi-infected red blood cells and modulation of regulatory T cell and dendritic cell responses. PLoS One 2013; 8:e81409. [PMID: 24312297 PMCID: PMC3842419 DOI: 10.1371/journal.pone.0081409] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 10/12/2013] [Indexed: 12/11/2022] Open
Abstract
It is postulated that accumulation of malaria-infected Red Blood Cells (iRBCs) in the liver could be a parasitic escape mechanism against full destruction by the host immune system. Therefore, we evaluated the in vivo mechanism of this accumulation and its potential immunological consequences. A massive liver accumulation of P. c. chabaudi AS-iRBCs (Pc-iRBCs) was observed by intravital microscopy along with an over expression of ICAM-1 on day 7 of the infection, as measured by qRT-PCR. Phenotypic changes were also observed in regulatory T cells (Tregs) and dendritic cells (DCs) that were isolated from infected livers, which indicate a functional role for Tregs in the regulation of the liver inflammatory immune response. In fact, the suppressive function of liver-Tregs was in vitro tested, which demonstrated the capacity of these cells to suppress naive T cell activation to the same extent as that observed for spleen-Tregs. On the other hand, it is already known that CD4+ T cells isolated from spleens of protozoan parasite-infected mice are refractory to proliferate in vivo. In our experiments, we observed a similar lack of in vitro proliferative capacity in liver CD4+ T cells that were isolated on day 7 of infection. It is also known that nitric oxide and IL-10 are partially involved in acute phase immunosuppression; we found high expression levels of IL-10 and iNOS mRNA in day 7-infected livers, which indicates a possible role for these molecules in the observed immune suppression. Taken together, these results indicate that malaria parasite accumulation within the liver could be an escape mechanism to avoid sterile immunity sponsored by a tolerogenic environment.
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27
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HLA class II (DR0401) molecules induce Foxp3+ regulatory T cell suppression of B cells in Plasmodium yoelii strain 17XNL malaria. Infect Immun 2013; 82:286-97. [PMID: 24166949 DOI: 10.1128/iai.00272-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Unlike human malaria parasites that induce persistent infection, some rodent malaria parasites, like Plasmodium yoelii strain 17XNL (Py17XNL), induce a transient (self-curing) malaria infection. Cooperation between CD4 T cells and B cells to produce antibodies is thought to be critical for clearance of Py17XNL parasites from the blood, with major histocompatibility complex (MHC) class II molecules being required for activation of CD4 T cells. In order to better understand the correspondence between murine malaria models and human malaria, and in particular the role of MHC (HLA) class II molecules, we studied the ability of humanized mice expressing human HLA class II molecules to clear Py17XNL infection. We showed that humanized mice expressing HLA-DR4 (DR0401) molecules and lacking mouse MHC class II molecules (EA(0)) have impaired production of specific antibodies to Py17XNL and cannot cure the infection. In contrast, mice expressing HLA-DR4 (DR0402), HLA-DQ6 (DQ0601), HLA-DQ8 (DQ0302), or HLA-DR3 (DR0301) molecules in an EA(0) background were able to elicit specific antibodies and self-cure the infection. In a series of experiments, we determined that the inability of humanized DR0401.EA(0) mice to elicit specific antibodies was due to expansion and activation of regulatory CD4(+) Foxp3(+) T cells (Tregs) that suppressed B cells to secrete antibodies through cell-cell interactions. Treg depletion allowed the DR0401.EA(0) mice to elicit specific antibodies and self-cure the infection. Our results demonstrated a differential role of MHC (HLA) class II molecules in supporting antibody responses to Py17XNL malaria and revealed a new mechanism by which malaria parasites stimulate B cell-suppressogenic Tregs that prevent clearance of infection.
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28
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Silva-Filho JL, Souza MC, Ferreira-DaSilva CT, Silva LS, Costa MFS, Padua TA, Henriques MDG, Morrot A, Savino W, Caruso-Neves C, Pinheiro AAS. Angiotensin II is a new component involved in splenic T lymphocyte responses during Plasmodium berghei ANKA infection. PLoS One 2013; 8:e62999. [PMID: 23646169 PMCID: PMC3639972 DOI: 10.1371/journal.pone.0062999] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 03/29/2013] [Indexed: 01/06/2023] Open
Abstract
The contribution of T cells in severe malaria pathogenesis has been described. Here, we provide evidence for the potential role of angiotensin II (Ang II) in modulating splenic T cell responses in a rodent model of cerebral malaria. T cell activation induced by infection, determined by 3 to 4-fold enhancement in CD69 expression, was reduced to control levels when mice were treated with 20 mg/kg losartan (IC₅₀ = 0.966 mg/kg/d), an AT₁ receptor antagonist, or captopril (IC₅₀ = 1.940 mg/kg/d), an inhibitor of angiotensin-converting enzyme (ACE). Moreover, the production of interferon-γ and interleukin-17 by CD4+ T cells diminished 67% and 70%, respectively, by both treatments. Losartan reduced perforin expression in CD8+ T cells by 33% while captopril completely blocked it. The upregulation in chemokine receptor expression (CCR2 and CCR5) observed during infection was abolished and CD11a expression was partially reduced when mice were treated with drugs. T cells activated by Plasmodium berghei ANKA antigens showed 6-fold enhance in AT₁ levels in comparison with naive cells. The upregulation of AT₁ expression was reduced by losartan (80%) but not by captopril. Our results suggest that the AT₁/Ang II axis has a role in the establishment of an efficient T cell response in the spleen and therefore could participate in a misbalanced parasite-induced T cell immune response during P. berghei ANKA infection.
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Affiliation(s)
- João Luiz Silva-Filho
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | | | | | - Leandro Souza Silva
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | | | - Tatiana Almeida Padua
- Instituto de Tecnologia em Fármacos, Fundação Oswaldo Cruz, Rio de Janeiro, RJ, Brazil
| | | | - Alexandre Morrot
- Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Wilson Savino
- Departamento de Imunologia, Fundação Oswaldo Cruz, Rio de Janeiro, RJ, Brazil
| | - Celso Caruso-Neves
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Instituto Nacional de Ciência e Tecnologia em Biologia e Bioimagem, Conselho Nacional de Desenvolvimento Científico e Tecnológico/MCT, Rio de Janeiro, RJ, Brazil
| | - Ana Acacia Sá Pinheiro
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Instituto Nacional para Pesquisa Translacional em Saúde e Ambiente na Região Amazônica, Conselho Nacional de Desenvolvimento Científico e Tecnológico/MCT, Rio de Janeiro, RJ, Brazil
- * E-mail:
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29
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Toxoplasma gondii infection induces suppression in a mouse model of allergic airway inflammation. PLoS One 2012; 7:e43420. [PMID: 22952678 PMCID: PMC3429463 DOI: 10.1371/journal.pone.0043420] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 07/20/2012] [Indexed: 11/19/2022] Open
Abstract
Allergic asthma is an inflammatory disorder characterized by infiltration of the airway wall with inflammatory cells driven mostly by activation of Th2-lymphocytes, eosinophils and mast cells. There is a link between increased allergy and a reduction of some infections in Western countries. Epidemiological data also show that respiratory allergy is less frequent in people exposed to orofecal and foodborne microbes such as Toxoplasma gondii. We previously showed that both acute and chronic parasite T. gondii infection substantially blocked development of airway inflammation in adult BALB/c mice. Based on the high levels of IFN-γ along with the reduction of Th2 phenotype, we hypothesized that the protective effect might be related to the strong Th1 immune response elicited against the parasite. However, other mechanisms could also be implicated. The possibility that regulatory T cells inhibit allergic diseases has received growing support from both animal and human studies. Here we investigated the cellular mechanisms involved in T. gondii induced protection against allergy. Our results show for the first time that thoracic lymph node cells from mice sensitized during chronic T. gondii infection have suppressor activity. Suppression was detected both in vitro, on allergen specific T cell proliferation and in vivo, on allergic lung inflammation after adoptive transference from infected/sensitized mice to previously sensitized animals. This ability was found to be contact- independent and correlated with high levels of TGF-β and CD4+FoxP3+ cells.
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Wang GG, Chen G, Feng H, Liu J, Jiang YJ, Shang H, Cao YM. Plasmodium chabaudi AS: distinct CD4(+)CD25(+)Foxp3(+) regulatory T cell responses during infection in DBA/2 and BALB/c mice. Parasitol Int 2012; 62:24-31. [PMID: 22971347 DOI: 10.1016/j.parint.2012.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 08/11/2012] [Accepted: 08/19/2012] [Indexed: 11/26/2022]
Abstract
Malaria infections display variation patterns of clinical course and outcome. Although CD4(+)CD25(+)Foxp3(+) regulatory T (Treg) cells play an essential role in immune homeostasis, the immune regulatory roles involved in malaria infection remains to be elucidated. Herein, we compared the disparity in Treg cells response during the course of blood stage Plasmodium chabaudi chabaudi AS (P. c chabaudi AS) infection in DBA/2 and BALB/c mice. BALB/c mice initiated a Th1/Th2 profile respond to P. c chabaudi AS infection, but DBA/2 mice failed to control P. c chabaudi AS infection and almost of them died post-peak parasitemia. At the peak parasitemia, we found that higher proportion of Treg cells with elevated Foxp3 expression in DBA/2 than in BALB/c mice. We used anti-CD25 mAb to deplete Treg cells and found that the survival time and rate were prolonged in DBA/2 mice treated with anti-CD25 mAb. Treatment with anti-CD25 mAb in vivo led to enhanced pro-inflammation responses and Foxp3 expression decline on Treg cells. In contrast, after DBA/2 was treatment with anti-IL-10R mAb, IL-10R blockade in vivo caused excessive pro-inflammation responses and Foxp3 expression loss on CD4(+)CD25(+) T cells. Earlier death was found in all of DBA/2 mice with anti-IL-10R mAb. It suggested that IL-2 and IL-10 signal involved in maintaining Foxp3 expression on Treg cells. In all, the moderate suppressive activity of Treg cells may facilitate resistance to P. c chabaudi AS infection.
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Affiliation(s)
- Ge-Ge Wang
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, China
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Feng Y, Zhu X, Wang Q, Jiang Y, Shang H, Cui L, Cao Y. Allicin enhances host pro-inflammatory immune responses and protects against acute murine malaria infection. Malar J 2012; 11:268. [PMID: 22873687 PMCID: PMC3472178 DOI: 10.1186/1475-2875-11-268] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Accepted: 07/22/2012] [Indexed: 12/19/2022] Open
Abstract
Background During malaria infection, multiple pro-inflammatory mediators including IFN-γ, TNF and nitric oxide (NO) play a crucial role in the protection against the parasites. Modulation of host immunity is an important strategy to improve the outcome of malaria infection. Allicin is the major biologically active component of garlic and shows anti-microbial activity. Allicin is also active against protozoan parasites including Plasmodium, which is thought to be mediated by inhibiting cysteine proteases. In this study, the immunomodulatory activities of allicin were assessed during acute malaria infection using a rodent malaria model Plasmodium yoelii 17XL. Methods To determine whether allicin modulates host immune responses against malaria infection, mice were treated with allicin after infection with P. yoelii 17XL. Mortality was checked daily and parasitaemia was determined every other day. Pro-inflammatory mediators and IL-4 were quantified by ELISA, while NO level was determined by the Griess method. The populations of dendritic cells (DCs), macrophages, CD4+ T and regulatory T cells (Treg) were assessed by FACS. Results Allicin reduced parasitaemia and prolonged survival of the host in a dose-dependent manner. This effect is at least partially due to improved host immune responses. Results showed that allicin treatment enhanced the production of pro-inflammatory mediators such as IFN-γ, TNF, IL-12p70 and NO. The absolute numbers of CD4+ T cells, DCs and macrophages were significantly higher in allicin-treated mice. In addition, allicin promoted the maturation of CD11c+ DCs, whereas it did not cause major changes in IL-4 and the level of anti-inflammatory cytokine IL-10. Conclusions Allicin could partially protect host against P. yoelii 17XL through enhancement of the host innate and adaptive immune responses.
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Affiliation(s)
- Yonghui Feng
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, China
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Abel S, Lückheide N, Westendorf AM, Geffers R, Roers A, Müller W, Sparwasser T, Matuschewski K, Buer J, Hansen W. Strong impact of CD4+ Foxp3+ regulatory T cells and limited effect of T cell-derived IL-10 on pathogen clearance during Plasmodium yoelii infection. THE JOURNAL OF IMMUNOLOGY 2012; 188:5467-77. [PMID: 22544931 DOI: 10.4049/jimmunol.1102223] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
It is well established that CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) play a crucial role in the course of different infectious diseases. However, contradictory results have been published regarding to malaria infection. In this study, we report that specific ablation of Foxp3(+) Tregs in Plasmodium yoelii-infected DEREG-BALB/c mice leads to an increase in T cell activation accompanied by a significant decrease in parasitemia. To better understand how Foxp3(+) Tregs orchestrate this phenotype, we used microarrays to analyze CD4(+)CD25(+)Foxp3(+) Tregs and CD4(+)CD25(-)Foxp3(-) T cells in the course of P. yoelii infection. Using this approach we identified genes specifically upregulated in CD4(+)CD25(+)Foxp3(+) Tregs in the course of infection, such as G-protein-coupled receptor 83 and Socs2. This analysis also revealed that both CD4(+)CD25(+)Foxp3(+) Tregs and CD4(+)CD25(-)Foxp3(-) T cells upregulate CTLA-4, granzyme B, and, more strikingly, IL-10 during acute blood infection. Therefore, we aimed to define the function of T cell-derived IL-10 in this context by Cre/loxP-mediated selective conditional inactivation of the IL-10 gene in T cells. Unexpectedly, IL-10 ablation in T cells exerts only a minor effect on parasite clearance, even though CD8(+) T cells are more strongly activated, the production of IFN-γ and TNF-α by CD4(+)CD25(-) T cells is increased, and the suppressive activity of CD4(+)CD25(+) Tregs is reduced upon infection. In summary, these results suggest that CD4(+)Foxp3(+) Tregs modulate the course of P. yoelii infection in BALB/c mice. Moreover, CD4(+) T cell-derived IL-10 affects T effector function and Treg activity, but has only a limited direct effect on parasite clearance in this model.
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Affiliation(s)
- Simone Abel
- Institute of Medical Microbiology, University Hospital Essen, University Duisburg-Essen, 45122 Essen, Germany
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Freitas do Rosario AP, Langhorne J. T cell-derived IL-10 and its impact on the regulation of host responses during malaria. Int J Parasitol 2012; 42:549-55. [PMID: 22549022 DOI: 10.1016/j.ijpara.2012.03.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Revised: 03/02/2012] [Accepted: 03/24/2012] [Indexed: 02/04/2023]
Abstract
Despite intense research, malaria still is the one of the most devastating diseases killing more people than any other parasitic infection. In an attempt to control the infection, the host immune system produces a potent pro-inflammatory response. However, this response is also associated with complications, such as severe anaemia, hypoglycaemia and cerebral malaria. This pronounced production of pro-inflammatory cytokines response is a common feature of malaria caused by parasites infecting humans as well as rodents and primates. A balance between pro- and anti-inflammatory responses may be fundamental to the elimination of the parasite without inducing excessive host pathology. IL-10 is a key cytokine that has been shown to have an important regulatory function in establishing this balance in malaria. Here we discuss which cells can produce IL-10 during infection, and present an overview of the evidence showing that T-cell derived IL-10 plays an important role in regulating malaria pathology. Many different subsets of T cells can produce IL-10, however, evidence is accumulating that it is effector Th1 CD4(+) T cells which provide the crucial source that down-regulates inflammatory pathology during blood-stage malaria infections.
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Zago CA, Bortoluci KR, Sardinha LR, Pretel FD, Castillo-Méndez SI, Freitas do Rosário AP, Hiyane MI, Muxel SM, Rodriguez-Málaga SM, Abrahamsohn IA, Álvarez JM, D'Império Lima MR. Anti-IL-2 treatment impairs the expansion of T(reg) cell population during acute malaria and enhances the Th1 cell response at the chronic disease. PLoS One 2012; 7:e29894. [PMID: 22272258 PMCID: PMC3260167 DOI: 10.1371/journal.pone.0029894] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 12/07/2011] [Indexed: 01/01/2023] Open
Abstract
Plasmodium chabaudi infection induces a rapid and intense splenic CD4(+) T cell response that contributes to both disease pathogenesis and the control of acute parasitemia. The subsequent development of clinical immunity to disease occurs concomitantly with the persistence of low levels of chronic parasitemia. The suppressive activity of regulatory T (T(reg)) cells has been implicated in both development of clinical immunity and parasite persistence. To evaluate whether IL-2 is required to induce and to sustain the suppressive activity of T(reg) cells in malaria, we examined in detail the effects of anti-IL-2 treatment with JES6-1 monoclonal antibody (mAb) on the splenic CD4(+) T cell response during acute and chronic P. chabaudi AS infection in C57BL/6 mice. JES6-1 treatment on days 0, 2 and 4 of infection partially inhibits the expansion of the CD4(+)CD25(+)Foxp3(+) cell population during acute malaria. Despite the concomitant secretion of IL-2 and expression of high affinity IL-2 receptor by large CD4(+) T cells, JES6-1 treatment does not impair effector CD4(+) T cell activation and IFN-γ production. However, at the chronic phase of the disease, an enhancement of cellular and humoral responses occurs in JES6-1-treated mice, with increased production of TNF-α and parasite-specific IgG2a antibodies. Furthermore, JES6-1 mAb completely blocked the in vitro proliferation of CD4(+) T cells from non-treated chronic mice, while it further increased the response of CD4(+) T cells from JES6-1-treated chronic mice. We conclude that JES6-1 treatment impairs the expansion of T(reg) cell population during early P. chabaudi malaria and enhances the Th1 cell response in the late phase of the disease.
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Affiliation(s)
- Cláudia A Zago
- Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, São Paulo, Brasil.
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Hamza E, Gerber V, Steinbach F, Marti E. Equine CD4(+) CD25(high) T cells exhibit regulatory activity by close contact and cytokine-dependent mechanisms in vitro. Immunology 2011; 134:292-304. [PMID: 21977999 DOI: 10.1111/j.1365-2567.2011.03489.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Horses are particularly prone to allergic and autoimmune diseases, but little information about equine regulatory T cells (Treg) is currently available. The aim of this study therefore was to investigate the existence of CD4(+) Treg cells in horses, determine their suppressive function as well as their mechanism of action. Freshly isolated peripheral blood mononuclear cells (PBMC) from healthy horses were examined for CD4, CD25 and forkhead box P3 (FoxP3) expression. We show that equine FoxP3 is expressed constitutively by a population of CD4(+) CD25(+) T cells, mainly in the CD4(+) CD25(high) subpopulation. Proliferation of CD4(+) CD25(-) sorted cells stimulated with irradiated allogenic PBMC was significantly suppressed in co-culture with CD4(+) CD25(high) sorted cells in a dose-dependent manner. The mechanism of suppression by the CD4(+) CD25(high) cell population is mediated by close contact as well as interleukin (IL)-10 and transforming growth factor-β1 (TGF-β1) and probably other factors. In addition, we studied the in vitro induction of CD4(+) Treg and their characteristics compared to those of freshly isolated CD4(+) Treg cells. Upon stimulation with a combination of concanavalin A, TGF-β1 and IL-2, CD4(+) CD25(+) T cells which express FoxP3 and have suppressive capability were induced from CD4(+) CD25(-) cells. The induced CD4(+) CD25(high) express higher levels of IL-10 and TGF-β1 mRNA compared to the freshly isolated ones. Thus, in horses as in man, the circulating CD4(+) CD25(high) subpopulation contains natural Treg cells and functional Treg can be induced in vitro upon appropriate stimulation. Our study provides the first evidence of the regulatory function of CD4(+) CD25(+) cells in horses and offers insights into ex vivo manipulation of Treg cells.
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Affiliation(s)
- Eman Hamza
- Department of Clinical Research and Veterinary Public Health, University of Bern, Bern, Switzerland.
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Feng H, Zhu XT, Qi ZM, Wang QH, Wang GG, Pan YY, Li Y, Zheng L, Jiang YJ, Shang H, Cui L, Cao YM. Transient Attenuated Foxp3 Expression on CD4+ T cells Treated with 7D4 mAb Contributes to the Control of Parasite Burden in DBA / 2 Mice Infected with Lethal Plasmodium chabaudi chabaudi AS. Scand J Immunol 2011; 75:46-53. [DOI: 10.1111/j.1365-3083.2011.02622.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Adalid-Peralta L, Fragoso G, Fleury A, Sciutto E. Mechanisms underlying the induction of regulatory T cells and its relevance in the adaptive immune response in parasitic infections. Int J Biol Sci 2011; 7:1412-26. [PMID: 22110392 PMCID: PMC3221948 DOI: 10.7150/ijbs.7.1412] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 10/01/2011] [Indexed: 12/22/2022] Open
Abstract
To fulfill its function, the immune system must detect and interpret a wide variety of signals and adjust the magnitude, duration, and specific traits of each response during the complex host-parasite relationships in parasitic infections. Inflammation must be tightly regulated since uncontrolled inflammation may be as destructive as the triggering stimulus and leads to immune-mediated tissue injury. During recent years, increasing evidence points to regulatory T cells (Tregs) as key anti-inflammatory cells, critically involved in limiting the inflammatory response. Herein, we review the published information on the induction of Tregs and summarize the most recent findings on Treg generation in parasitic diseases.
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Sun J, Han ZB, Liao W, Yang SG, Yang Z, Yu J, Meng L, Wu R, Han ZC. Intrapulmonary delivery of human umbilical cord mesenchymal stem cells attenuates acute lung injury by expanding CD4+CD25+ Forkhead Boxp3 (FOXP3)+ regulatory T cells and balancing anti- and pro-inflammatory factors. Cell Physiol Biochem 2011; 27:587-96. [PMID: 21691076 DOI: 10.1159/000329980] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/27/2011] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Systemic and local inflammatory processes play key, mainly detrimental roles in the pathophysiology of acute lung injury (ALI). The present study was designed to determine whether human umbilical cord mesenchymal stem cells (UCMSC) are able to act on CD4(+)CD25(+) Foxp3(+)Treg cells and lead to an improvement in ALI. METHODS Mice were administered intratracheally endotoxin (lipopolysaccharide [LPS]) and received intrapulmonary 1×10(6) UCMSC 4 hours after challenge. The CD4(+)CD25(+) Foxp3(+)Treg, survival time, body weight, histology and lung injury scores were assessed after transplantation of UCMSC. In addition, anti-inflammatory factor IL10 and pro-inflammatory mediators production including tumor necrosis factor-a (TNF-α), macrophage inflammatory protein-2(MIP-2) and interferon-γ (IFN-γ) were detected. RESULTS Transplantation of UCMSC resulted in significant increase in the level of CD4(+)CD25(+) Foxp3(+)Treg in ALI. Increased level of anti-inflammatory factor IL-10 and reduced levels of TNF-α, MIP-2 and IFN-γ were simultaneously observed in ALI in comparison with control mice. CONCLUSION Our data demonstrate for the first time that transplantation of UCMSC ameliorates ALI by enhancing the diminished levels of alveolar CD4(+)CD25(+) Foxp3(+)Treg and balancing anti- and pro-inflammatory factors in ALI mice.
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Affiliation(s)
- Jun Sun
- The State Key Laboratory of Experimental Hematology, National Engineering Technology Research Center of Stem Cells, Institute of Hematology and Hospital of Blood Diseases, Chinese Academy of Medical Sciences, 288 Nanjing Road, Tianjin, China.
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Sarfo BY, Wilson NO, Bond VC, Stiles JK. Plasmodium berghei ANKA infection increases Foxp3, IL-10 and IL-2 in CXCL-10 deficient C57BL/6 mice. Malar J 2011; 10:69. [PMID: 21439091 PMCID: PMC3078901 DOI: 10.1186/1475-2875-10-69] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 03/28/2011] [Indexed: 12/30/2022] Open
Abstract
Background Cerebral malaria (CM) is a major cause of malaria mortality. Sequestration of infected red blood cells and leukocytes in brain vessels coupled with the production of pro-inflammatory factors contribute to CM. CXCL-10 a chemokine that is chemotactic to T cells has been linked to fatal CM. Mice deficient for CXCL-10 gene are resistant to murine CM, while antibody ablation of CXCL-10 enhanced the production of regulatory T cells (CD4+Cd25+Foxp3+) and IL-10 which regulate the immune system. Interleukin-2 (IL-2), a pro-inflammatory cytokine implicated in malaria pathogenesis has also been shown to be a key regulator of Foxp3. However the role of Foxp3 in resistant murine CM is not well understood. Methods The hypothesis that resistance of CXCL-10-/- mice to murine CM may be due to enhanced expression of Foxp3 in concert with IL-10 and IL-2 was tested. CXCL-10-/- and WT C57BL/6 mice were infected with Plasmodium berghei ANKA and evaluated for CM symptoms. Brain, peripheral blood mononuclear cells (PBMCs) and plasma were harvested from infected and uninfected mice at days 2, 4 and 8. Regulatory T cells (CD4+CD25+) and non-T regs (CD4+CD25-) were isolated from PBMCs and cultured with P. berghei antigens in vitro with dendritic cells as antigen presenting cells. Regulatory T cell transcription and specific factor Foxp3, was evaluated in mouse brain and PBMCs by realtime-PCR and Western blots while IL-10, and IL-2 were evaluated in plasma and cultured supernatants by ELISA. Results Wild type mice exhibited severe murine CM symptoms compared with CXCL-10-/- mice. Foxp3 mRNA and protein in brain and PBMC's of CXCL-10-/- mice was significantly up-regulated (p < 0.05) by day 4 post-infection (p.i) compared with WT. Plasma levels of IL-10 and IL-2 in infected CXCL-10-/- were higher than in WT mice (p < 0.05) at days 2 and 4 p.i. Ex-vivo CD4+CD25+ T cells from CXCL-10-/- re-stimulated with P. berghei antigens produced more IL-10 than WT CD4+CD25+ T cells. Conclusion The results indicate that in the absence of CXCL-10, the resulting up-regulation of Foxp3, IL-10 and IL-2 may be involved in attenuating fatal murine CM.
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Affiliation(s)
- Bismark Y Sarfo
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, 720 Westview Drive, South West, Atlanta Georgia, GA 30310, USA
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Farias AS, Talaisys RL, Blanco YC, Lopes SCP, Longhini ALF, Pradella F, Santos LMB, Costa FTM. Regulatory T cell induction during Plasmodium chabaudi infection modifies the clinical course of experimental autoimmune encephalomyelitis. PLoS One 2011; 6:e17849. [PMID: 21464982 PMCID: PMC3064572 DOI: 10.1371/journal.pone.0017849] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 02/10/2011] [Indexed: 11/19/2022] Open
Abstract
Background Experimental autoimmune encephalomyelitis (EAE) is used as an animal model for human multiple sclerosis (MS), which is an inflammatory demyelinating autoimmune disease of the central nervous system characterized by activation of Th1 and/or Th17 cells. Human autoimmune diseases can be either exacerbated or suppressed by infectious agents. Recent studies have shown that regulatory T cells play a crucial role in the escape mechanism of Plasmodium spp. both in humans and in experimental models. These cells suppress the Th1 response against the parasite and prevent its elimination. Regulatory T cells have been largely associated with protection or amelioration in several autoimmune diseases, mainly by their capacity to suppress proinflammatory response. Methodology/Principal Findings In this study, we verified that CD4+CD25+ regulatory T cells (T regs) generated during malaria infection (6 days after EAE induction) interfere with the evolution of EAE. We observed a positive correlation between the reduction of EAE clinical symptoms and an increase of parasitemia levels. Suppression of the disease was also accompanied by a decrease in the expression of IL-17 and IFN-γ and increases in the expression of IL-10 and TGF-β1 relative to EAE control mice. The adoptive transfer of CD4+CD25+ cells from P. chabaudi-infected mice reduced the clinical evolution of EAE, confirming the role of these T regs. Conclusions/Significance These data corroborate previous findings showing that infections interfere with the prevalence and evolution of autoimmune diseases by inducing regulatory T cells, which regulate EAE in an apparently non-specific manner.
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MESH Headings
- Animals
- Autoimmunity/immunology
- Cell Survival
- Cytokines/genetics
- Cytokines/metabolism
- Disease Progression
- Encephalomyelitis, Autoimmune, Experimental/complications
- Encephalomyelitis, Autoimmune, Experimental/genetics
- Encephalomyelitis, Autoimmune, Experimental/immunology
- Encephalomyelitis, Autoimmune, Experimental/parasitology
- Gene Expression Regulation
- Humans
- Interleukin-2 Receptor alpha Subunit/metabolism
- Malaria/complications
- Malaria/genetics
- Malaria/immunology
- Malaria/parasitology
- Mice
- Mice, Inbred C57BL
- Plasmodium chabaudi/immunology
- T-Lymphocytes, Regulatory/immunology
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Affiliation(s)
- Alessandro S. Farias
- Departmento de Genética, Evolução e Bioagentes, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
- * E-mail: (ASF); (FTMC)
| | - Rafael L. Talaisys
- Departmento de Genética, Evolução e Bioagentes, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Yara C. Blanco
- Departmento de Genética, Evolução e Bioagentes, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Stefanie C. P. Lopes
- Departmento de Genética, Evolução e Bioagentes, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Ana Leda F. Longhini
- Departmento de Genética, Evolução e Bioagentes, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Fernando Pradella
- Departmento de Genética, Evolução e Bioagentes, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Leonilda M. B. Santos
- Departmento de Genética, Evolução e Bioagentes, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Fabio T. M. Costa
- Departmento de Genética, Evolução e Bioagentes, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil
- * E-mail: (ASF); (FTMC)
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Partial depletion of CD4(+)CD25(+)Foxp3(+) T regulatory cells significantly increases morbidity during acute phase Toxoplasma gondii infection in resistant BALB/c mice. Microbes Infect 2011; 13:394-404. [PMID: 21262371 DOI: 10.1016/j.micinf.2011.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 11/14/2010] [Accepted: 01/11/2011] [Indexed: 11/23/2022]
Abstract
CD4(+)CD25(+)Foxp3(+) T regulatory (Treg) cells, are known to regulate responses to infectious agents. Here we compared disease progression in BALB/c and C57BL/6(B6) mice infected perorally with Toxoplasma gondii for 7 days and examined the affect of partial depletion of Treg cells in these mice. BALB/c mice were seen to be resistant to peroral infection whereas B6 mice were susceptible in terms of mortality. Although the depletion of Treg cells before infection had no effect on the survival of B6 or BALB/c mice, it resulted in increased parasite burdens in BALB/c mice, especially in the lamina propria, but not in B6 mice. Pro-inflammatory cytokines were also increased in Treg cells depleted BALB/c mice as compared to B6 mice. In addition Treg cell depleted BALB/c mice displayed increased ileal histopathology compared to their non-treated counterparts. These findings provide evidence for the contribution of Treg cells, in the resistance of BALB/c mice against peroral T. gondii infection.
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Abstract
Infectious agents have intimately co-evolved with the host immune system, acquiring a portfolio of highly sophisticated mechanisms to modulate immunity. Among the common strategies developed by viruses, bacteria, protozoa, helminths, and fungi is the manipulation of the regulatory T cell network in order to favor pathogen survival and transmission. Treg activity also benefits the host in many circumstances by controlling immunopathogenic reactions to infection. Interestingly, some pathogens are able to directly induce the conversion of naive T cells into suppressive Foxp3-expressing Tregs, while others activate pre-existing natural Tregs, in both cases repressing pathogen-specific effector responses. However, Tregs can also act to promote immunity in certain settings, such as in initial stages of infection when effector cells must access the site of infection, and subsequently in ensuring generation of effector memory. Notably, there is little current information on whether infections selectively drive pathogen-specific Tregs, and if so whether these cells are also reactive to self-antigens. Further analysis of specificity, together with a clearer picture of the relative dynamics of Treg subsets over the course of disease, should lead to rational strategies for immune intervention to optimize immunity and eliminate infection.
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Abstract
Plasmodium falciparum malaria causes 500 million clinical cases with approximately one million deaths each year. After many years of exposure, individuals living in endemic areas develop a form of clinical immunity to disease known as premunition, which is characterised by low parasite burdens rather than sterilising immunity. The reason why malaria parasites persist under a state of premunition is unknown but it has been suggested that suppression of protective immunity might be a mechanism leading to parasite persistence. Although acquired immunity limits the clinical impact of infection and provides protection against parasite replication, experimental evidence indicates that cell-mediated immune responses also result in detrimental inflammation and contribute to the aetiology of severe disease. Thus, an appropriate regulatory balance between protective immune responses and immune-mediated pathology is required for a favourable outcome of infection. As natural regulatory T (Treg) cells are identified as an immunosuppressive lineage able to modulate the magnitude of effector responses, several studies have investigated whether this cell population plays a role in balancing protective immunity and pathogenesis during malaria. The main findings to date are summarised in this review and the implication for the induction of pathogenesis and immunity to malaria is discussed.
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Affiliation(s)
- Diana S Hansen
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.
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Zheng W, Wang QH, Feng H, Liu J, Meng HR, Cao YM. CD4+CD25+Foxp3+ regulatory T cells prevent the development of Th1 immune response by inhibition of dendritic cell function during the early stage of Plasmodium yoelii infection in susceptible BALB/c mice. Folia Parasitol (Praha) 2010; 56:242-50. [PMID: 20128236 DOI: 10.14411/fp.2009.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Protective immunity against murine malaria infection depends largely on the establishment of effective Th1 immune response during the early stages of infection. Experimental data suggest that the death of Plasmodium yoelii 17XL (Py 17XL) susceptible BALB/c mice results from the suppression of Th1 immune response mediated by CD4+CD25+Foxp3+ regulatory T cells (Tregs). However, the mechanism by which Tregs regulate Th1 immune response is poorly understood. Since immunity is initiated by dendritic cells (DCs), we analysed DC responses to Py 17XL in control and Treg-depleted BALB/c mice. Myeloid DC proliferation, phenotypic maturation and interleukin-12 (IL-12) production were strongly inhibited in control BALB/c mice. In contrast, plasmacytoid DC proliferation and IL-10 production were strongly enhanced in control BALB/c mice. In-vivo depletion of Tregs resulted in significantly reversed inhibition of DC response, which may contribute to the establishment of Th1 immune response, indicating that Tregs contribute to the suppression of Th1 immune response during malaria. These findings suggest Tregs contribute to prevent Th1 immune response establishment during the early stage of Py 17XL infection by inhibiting DC response.
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Affiliation(s)
- Wei Zheng
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China
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Bueno LL, Morais CG, Araújo FF, Gomes JAS, Corrêa-Oliveira R, Soares IS, Lacerda MV, Fujiwara RT, Braga ÉM. Plasmodium vivax: induction of CD4+CD25+FoxP3+ regulatory T cells during infection are directly associated with level of circulating parasites. PLoS One 2010; 5:e9623. [PMID: 20224778 PMCID: PMC2835751 DOI: 10.1371/journal.pone.0009623] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 02/19/2010] [Indexed: 11/29/2022] Open
Abstract
Circulation CD4+CD25+FoxP3+ regulatory T cells (Tregs) have been associated with the delicate balancing between control of overwhelming acute malaria infection and prevention of immune pathology due to disproportionate inflammatory responses to erythrocytic stage of the parasite. While the role of Tregs has been well-documented in murine models and P. falciparum infection, the phenotype and function of Tregs in P. vivax infection is still poorly characterized. In the current study, we demonstrated that patients with acute P. vivax infection presented a significant augmentation of circulating Tregs producing anti-inflammatory (IL-10 and TGF-β) as well as pro-inflammatory (IFN-γ, IL-17) cytokines, which was further positively correlated with parasite burden. Surface expression of GITR molecule and intracellular expression of CTLA-4 were significantly upregulated in Tregs from infected donors, presenting also a positive association between either absolute numbers of CD4+CD25+FoxP3+GITR+ or CD4+CD25+FoxP3+CTLA-4+ and parasite load. Finally, we demonstrate a suppressive effect of Treg cells in specific T cell proliferative responses of P. vivax infected subjects after antigen stimulation with Pv-AMA-1. Our findings indicate that malaria vivax infection lead to an increased number of activated Treg cells that are highly associated with parasite load, which probably exert an important contribution to the modulation of immune responses during P. vivax infection.
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Affiliation(s)
- Lilian Lacerda Bueno
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Cristiane Guimarães Morais
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Fernanda Fortes Araújo
- Laboratório de Imunologia Celular e Molecular, Instituto René Rachou, FIOCRUZ, Belo Horizonte, Brazil
| | - Juliana Assis Silva Gomes
- Laboratório de Imunologia Celular e Molecular, Instituto René Rachou, FIOCRUZ, Belo Horizonte, Brazil
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Rodrigo Corrêa-Oliveira
- Laboratório de Imunologia Celular e Molecular, Instituto René Rachou, FIOCRUZ, Belo Horizonte, Brazil
| | - Irene Silva Soares
- Departamento de Análises Clínicas e Toxicológicas, Universidade de São Paulo, São Paulo, Brazil
| | | | - Ricardo Toshio Fujiwara
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- Laboratório de Imunologia Celular e Molecular, Instituto René Rachou, FIOCRUZ, Belo Horizonte, Brazil
| | - Érika Martins Braga
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- * E-mail:
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Finney OC, Riley EM, Walther M. Regulatory T cells in malaria – friend or foe? Trends Immunol 2010; 31:63-70. [DOI: 10.1016/j.it.2009.12.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 12/06/2009] [Accepted: 12/08/2009] [Indexed: 10/20/2022]
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Scholzen A, Minigo G, Plebanski M. Heroes or villains? T regulatory cells in malaria infection. Trends Parasitol 2010; 26:16-25. [DOI: 10.1016/j.pt.2009.10.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 10/09/2009] [Accepted: 10/15/2009] [Indexed: 12/14/2022]
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Reduction of Foxp3+ cells by depletion with the PC61 mAb induces mortality in resistant BALB/c mice infected with Toxoplasma gondii. J Biomed Biotechnol 2009; 2010:786078. [PMID: 20037737 PMCID: PMC2796377 DOI: 10.1155/2010/786078] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 09/09/2009] [Accepted: 09/14/2009] [Indexed: 11/26/2022] Open
Abstract
Regulatory T cells (Tregs) are CD4+Foxp3+ cells that modulate autoimmune responses. Tregs have been shown to be also involved during the immune response against infectious agents. The aim of this work is to study the role of Tregs during the infection with the intracellular protozoan Toxoplasma gondii. Resistant BALB/c mice were injected with 200 μg of anti-CD25 mAb (clone PC61) and 2 days later they were infected with 20 cysts of the ME49 strain of T. gondii. We observed that depleted mice showed 50–60% mortality during the acute infection. When FACS analysis was carried out, we observed that although injection of PC61 mAb eliminated 50% of Tregs, infected-depleted mice showed a similar percentage of CD25+Foxp3− (activated T cells, Tact) to those observed in infected nondepleted animals, demonstrating that in our depletion/infection system, injection of PC61 mAb did not hamper T cell activation while percentage of Tregs was reduced by 75% 10 days post infection. We concluded that Tregs are essential during protection in the acute phase of T. gondii infection.
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O'Connor RA, Taams LS, Anderton SM. Translational mini-review series on Th17 cells: CD4 T helper cells: functional plasticity and differential sensitivity to regulatory T cell-mediated regulation. Clin Exp Immunol 2009; 159:137-47. [PMID: 19912249 DOI: 10.1111/j.1365-2249.2009.04040.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
CD4(+) T cells display considerable flexibility in their effector functions, allowing them to tackle most effectively the range of pathogenic infections with which we are challenged. The classical T helper (Th) 1 and Th2 subsets have been joined recently by the Th17 lineage. If not controlled, the potent effector functions (chiefly cytokine production) of which these different cells are capable can lead to (sometimes fatal) autoimmune and allergic inflammation. The primary cell population tasked with providing this control appears to be CD4(+) regulatory T (T(reg)) cells expressing the forkhead box P3 (FoxP3) transcription factor. Here we consider the comparative capacity of FoxP3(+) T(regs) to influence the polarization, expansion and effector function of Th1, Th2 and Th17 cells in vitro and in vivo as well as in relation to human disease. This remains a particularly challenging series of interactions to understand, especially given our evolving understanding of T(reg) and T effector interrelationships, as well as recent insights into functional plasticity that cast doubt upon the wisdom of a strict categorization of T effector cells based on cytokine production.
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Affiliation(s)
- R A O'Connor
- University of Edinburgh, Centre for Inflammation Research and Centre for Multiple Sclerosis Research, Queen's Medical Research Institute, Edinburgh, UK.
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Investigation of memory responses following Plasmodium chabaudi AS infection in mice distinct in susceptibility to clinical malaria. Parasitol Res 2009; 106:283-7. [DOI: 10.1007/s00436-009-1597-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 08/03/2009] [Indexed: 11/25/2022]
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