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Janakiraman Vani

Bio: Janakiraman Vani is an academic researcher from French Institute of Health and Medical Research. The author has contributed to research in topics: Antigen & Antigen-presenting cell. The author has an hindex of 11, co-authored 23 publications receiving 607 citations. Previous affiliations of Janakiraman Vani include Center for Infectious Disease Research and Policy & Paris Descartes University.

Papers
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Journal ArticleDOI
TL;DR: Results reveal a novel mechanism of action of IVIg in achieving a therapeutic effect in autoimmune and allergic diseases, in which T(H)17 cells play a key modulatory role in sustaining the chronic inflammatory response.
Abstract: Background T H 17 cells play a critical role in the pathogenesis of several autoimmune and allergic diseases. Intravenous immunoglobulin (IVIg), a therapeutic preparation of polyclonal IgG that is increasingly used in the treatment of diverse autoimmune and allergic diseases, might target T H 17 cells to exert therapeutic effects. Objective We sought to examine whether IVIg interferes with the development and function of human T H 17 cells. Methods T H 17 cells were differentiated from naive human CD4 + T cells in the presence of TGF-β and IL-21. T H 17 cells were amplified by stimulating memory CD4 + T cells in the presence of IL-1β and IL-6. The effect of IVIg was examined on the differentiation and amplification of T H 17 cells, expression of the T H 17 lineage-specific transcription factor retinoic acid-related orphan receptor C, secretion of T H 17 effector cytokines, and phosphorylation of signal transducer and activator of transcription 3, a transcription factor that plays an important role in T H 17 cell development and function. Results IVIg inhibits the differentiation and amplification of human T H 17 cells, as well as the production of their effector cytokines IL-17A, IL-17F, IL-21, and CCL20. The inhibitory effects of IVIg on T H 17 cells are F(ab′) 2 dependent and involve interference with the expression of retinoic acid-related orphan receptor C and activation of signal transducer and activator of transcription 3. Also, IVIg significantly enhanced forkhead box protein 3–positive regulatory T cells among the memory CD4 + T cells. Conclusion These results reveal a novel mechanism of action of IVIg in achieving a therapeutic effect in autoimmune and allergic diseases, in which T H 17 cells play a key modulatory role in sustaining the chronic inflammatory response. Our results also suggest a reciprocal regulation of T H 17 and regulatory T-cell populations by IVIg.

133 citations

Journal ArticleDOI
TL;DR: Modulation of Tregs by IVIG represents a novel mode of action that explains the therapeutic effects of IVIG in T cell-mediated autoimmune diseases, however, the molecular mechanisms involved in IVIG-mediated modulation of T Regs are unclear and need further investigation.
Abstract: An altered immune homeostasis as a result of deficiency or defective function of CD4+CD25+FoxP3+ regulatory T cells (Tregs) is common in several autoimmune diseases. Hence, therapeutic strategies to render Tregs functionally competent are being investigated. Intravenous immunoglobulin (IVIG) is being increasingly used for the treatment of a wide range of autoimmune and inflammatory diseases. Recent studies have demonstrated that IVIG induces the expansion of Tregs and enhances their suppressive functions. These effects of IVIG on Tregs correlate with the beneficial effects of IVIG in patients with autoimmune diseases. Thus, modulation of Tregs by IVIG represents a novel mode of action that explains the therapeutic effects of IVIG in T cell-mediated autoimmune diseases. However, the molecular mechanisms involved in IVIG-mediated modulation of Tregs are unclear and need further investigation.

73 citations

Journal ArticleDOI
TL;DR: It is demonstrated that IVIg at low doses induces proliferation and immunoglobulin synthesis from B cells of CVID patients, and has an active role in regulating autoimmune and inflammatory responses through modulating B cell functions and thus imposing dynamic equilibrium of the immune system.

60 citations

Journal ArticleDOI
30 Nov 2009-PLOS ONE
TL;DR: The authors' CCR4 antagonists act as adjuvants augmenting human T cell proliferation in an in vitro immune response model and compound SP50 increases T cell and antibody responses in vivo when combined with vaccine antigens of Mycobacterium tuberculosis and Plasmodium yoelii in mice.
Abstract: Background Adjuvants enhance or modify an immune response that is made to an antigen. An antagonist of the chemokine CCR4 receptor can display adjuvant-like properties by diminishing the ability of CD4+CD25+ regulatory T cells (Tregs) to down-regulate immune responses. Methodology Here, we have used protein modelling to create a plausible chemokine receptor model with the aim of using virtual screening to identify potential small molecule chemokine antagonists. A combination of homology modelling and molecular docking was used to create a model of the CCR4 receptor in order to investigate potential lead compounds that display antagonistic properties. Three-dimensional structure-based virtual screening of the CCR4 receptor identified 116 small molecules that were calculated to have a high affinity for the receptor; these were tested experimentally for CCR4 antagonism. Fifteen of these small molecules were shown to inhibit specifically CCR4-mediated cell migration, including that of CCR4+ Tregs. Significance Our CCR4 antagonists act as adjuvants augmenting human T cell proliferation in an in vitro immune response model and compound SP50 increases T cell and antibody responses in vivo when combined with vaccine antigens of Mycobacterium tuberculosis and Plasmodium yoelii in mice.

58 citations


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01 Jan 1999
Abstract: The natural killer T (NKT) cell ligand α-galactosylceramide (α-GalCer) exhibits profound antitumor activities in vivo that resemble interleukin (IL)-12–mediated antitumor activities. Because of these similarities between the activities of α-GalCer and IL-12, we investigated the involvement of IL-12 in the activation of NKT cells by α-GalCer. We first established, using purified subsets of various lymphocyte populations, that α-GalCer selectively activates NKT cells for production of interferon (IFN)-γ. Production of IFN-γ by NKT cells in response to α-GalCer required IL-12 produced by dendritic cells (DCs) and direct contact between NKT cells and DCs through CD40/CD40 ligand interactions. Moreover, α-GalCer strongly induced the expression of IL-12 receptor on NKT cells from wild-type but not CD1−/− or Vα14−/− mice. This effect of α-GalCer required the production of IFN-γ by NKT cells and production of IL-12 by DCs. Finally, we showed that treatment of mice with suboptimal doses of α-GalCer together with suboptimal doses of IL-12 resulted in strongly enhanced natural killing activity and IFN-γ production. Collectively, these findings indicate an important role for DC-produced IL-12 in the activation of NKT cells by α-GalCer and suggest that NKT cells may be able to condition DCs for subsequent immune responses. Our results also suggest a novel approach for immunotherapy of cancer.

591 citations

Journal ArticleDOI
TL;DR: Th17 cells are associated with the pathogenesis of several autoimmune and inflammatory diseases, such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, psoriasis, inflammatory bowel disease, and allergy and asthma and the various therapeutic strategies under investigation to target them are discussed.
Abstract: Th17 cells that secrete the cytokines IL-17A and IL-17F and express lineage-specific transcription factor RORC (RORγt in mice) represent a distinct lineage of CD4 + T cells. Transforming growth factor-β and inflammatory cytokines, such as IL-6, IL-21, IL-1β, and IL-23, play central roles in the generation of Th17 cells. Th17 cells are critical for the clearance of extracellular pathogens, including Candida and Klebsiella . However, under certain conditions, these cells and their effector molecules, such as IL-17, IL-21, IL-22, GM-CSF, and CCL20, are associated with the pathogenesis of several autoimmune and inflammatory diseases, such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, psoriasis, inflammatory bowel disease, and allergy and asthma. This review discusses these disease states and the various therapeutic strategies under investigation to target Th17 cells, which include blocking the differentiation and amplification of Th17 cells, inhibiting or neutralizing the cytokines of Th17 cells, and suppressing the transcription factors specific for Th17 cells.

542 citations

Journal ArticleDOI
TL;DR: Convalescent plasma constitutes the first option in the current situation, since it has been successfully used in other coronaviruses outbreaks, and the benefits of PC are expected to be better achieved if used in non-critically hospitalized patients, in the hope of reducing morbidity and mortality.

402 citations

Journal ArticleDOI
TL;DR: This work reviewed available information and recent advances about ROS in the main immune cell types and gave summary about functions of these highly reactive molecules both in innate immunity as conservative defense mechanisms and in essential immune cells involved in adaptive immunity, and particularly in immune suppression.
Abstract: Reactive oxygen species (ROS) are a group of highly reactive chemicals containing oxygen produced either exogenously or endogenously. ROS are related to a wide variety of human disorders, such as chronic inflammation, age-related diseases and cancers. Besides, ROS are also essential for various biological functions, including cell survival, cell growth, proliferation and differentiation, and immune response. At present there are a number of excellent publications including some reviews about functions of these molecules either in normal cell biology or in pathophysiology. In this work, we reviewed available information and recent advances about ROS in the main immune cell types and gave summary about functions of these highly reactive molecules both in innate immunity as conservative defense mechanisms and in essential immune cells involved in adaptive immunity, and particularly in immune suppression.

372 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss relevant work focusing on the establishment of the intratumor balance, the dynamic changes in the populations of effector and regulatory T cells within the tumor, and the role of the tumor vasculature and its activation state in the recruitment of different T-cell subsets.
Abstract: The continual interaction of the immune system with a developing tumor is thought to result in the establishment of a dynamic state of equilibrium. This equilibrium depends on the balance between effector and regulatory T-cell compartments. Whereas regulatory T cells can infiltrate and accumulate within tumors, effector T cells fail to efficiently do so. Furthermore, effector T cells that do infiltrate the tumor become tightly controlled by different regulatory cellular subsets and inhibitory molecules. The outcome of this balance is critical to survival, and whereas in some cases the equilibrium can rapidly result in the elimination of the transformed cells by the immune system, in many other cases the tumor manages to escape immune control. In this review, we discuss relevant work focusing on the establishment of the intratumor balance, the dynamic changes in the populations of effector and regulatory T cells within the tumor, and the role of the tumor vasculature and its activation state in the recruitment of different T-cell subsets. Finally, we also discuss work associated to the manipulation of the immune response to tumors and its impact on the infiltration, accumulation, and function of tumor-reactive lymphocytes within the tumor microenvironment.

246 citations