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Central nervous system destruction mediated by glutamic acid decarboxylase-specific CD4+ T cells.

ABSTRACT: High titers of autoantibodies against glutamic acid decarboxylase (GAD) 65 are commonly observed in patients suffering from type 1 diabetes as well as stiff-person syndrome (SPS), a disorder that affects the CNS, and a variant of SPS, progressive encephalomyelitis with rigidity and myoclonus. Although there is a considerable amount of data focusing on the role of GAD65-specific CD4(+) T cells in type 1 diabetes, little is known about their role in SPS. In this study, we show that mice possessing a monoclonal GAD65-specific CD4(+) T cell population (4B5, PA19.9G11, or PA17.9G7) develop a lethal encephalomyelitis-like disease in the absence of any other T cells or B cells. GAD65-reactive CD4(+) T cells were found throughout the CNS in direct concordance with GAD65 expression and activated microglia: proximal to the circumventricular organs at the interface between the brain parenchyma and the blood-brain barrier. In the presence of B cells, high titer anti-GAD65 autoantibodies were generated, but these had no effect on the incidence or severity of disease. In addition, GAD65-specific CD4(+) T cells isolated from the brain were activated and produced IFN-gamma. These findings suggest that GAD65-reactive CD4(+) T cells alone mediate a lethal encephalomyelitis-like disease that may serve as a useful model to study GAD65-mediated diseases of the CNS.

SUBMITTER: Burton AR

PROVIDER: S-EPMC2989406 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Central nervous system destruction mediated by glutamic acid decarboxylase-specific CD4+ T cells.

Burton Amanda R AR Baquet Zachary Z Eisenbarth George S GS Tisch Roland R Smeyne Richard R Workman Creg J CJ Vignali Dario A A DA

Journal of immunology (Baltimore, Md. : 1950) 20100326 9

High titers of autoantibodies against glutamic acid decarboxylase (GAD) 65 are commonly observed in patients suffering from type 1 diabetes as well as stiff-person syndrome (SPS), a disorder that affects the CNS, and a variant of SPS, progressive encephalomyelitis with rigidity and myoclonus. Although there is a considerable amount of data focusing on the role of GAD65-specific CD4(+) T cells in type 1 diabetes, little is known about their role in SPS. In this study, we show that mice possessing ...[more]

PMID: 20348424

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Project description:BACKGROUND:CD4(+)CD25(+) regulatory T cell (Treg)-based immunotherapy is considered a promising regimen for controlling the progression of autoimmune diabetes. In this study, we tested the hypothesis that the therapeutic effects of Tregs in response to the antigenic epitope stimulation depend on the structural properties of the epitopes used. METHODOLOGY/PRINCIPAL FINDINGS:Splenic lymphocytes from nonobese diabetic (NOD) mice were stimulated with different glutamic acid decarboxylase (GAD)-derived epitopes for 7-10 days and the frequency and function of Tregs was analyzed. We found that, although all expanded Tregs showed suppressive functions in vitro, only p524 (GAD524-538)-expanded CD4(+)CD25(+) T cells inhibited diabetes development in the co-transfer models, while p509 (GAD509-528)- or p530 (GAD530-543)-expanded CD4(+)CD25(+) T cells had no such effects. Using computer-guided molecular modeling and docking methods, the differences in structural characteristics of these epitopes and the interaction mode (including binding energy and identified domains in the epitopes) between the above-mentioned epitopes and MHC class II I-A(g7) were analyzed. The theoretical results showed that the epitope p524, which induced protective Tregs, possessed negative surface-electrostatic potential and bound two chains of MHC class II I-A(g7), while the epitopes p509 and p530 which had no such ability exhibited positive surface-electrostatic potential and bound one chain of I-A(g7). Furthermore, p524 bound to I-A(g7) more stably than p509 and p530. Of importance, we hypothesized and subsequently confirmed experimentally that the epitope (GAD570-585, p570), which displayed similar characteristics to p524, was a protective epitope by showing that p570-expanded CD4(+)CD25(+) T cells suppressed the onset of diabetes in NOD mice. CONCLUSIONS/SIGNIFICANCE:These data suggest that molecular modeling-based structural analysis of epitopes may be an instrumental tool for prediction of protective epitopes to expand functional Tregs.

Project description:Little is known of glutamic acid decarboxylase antibodies (GAD-abs) in the paraneoplastic context. Clinical recognition of such cases will lead to prompt tumor diagnosis and appropriate treatment.To report the clinical and immunological features of patients with paraneoplastic neurological syndromes (PNS) and GAD-abs.Retrospective case series study and immunological investigations conducted in February 2014 in a center for autoimmune neurological disorders. Fifteen cases with GAD65-abs evaluated between 1995 and 2013 who fulfilled criteria of definite or possible PNS without concomitant onconeural antibodies were included in this study.Analysis of the clinical records of 15 patients and review of 19 previously reported cases. Indirect immunofluorescence with rat hippocampal neuronal cultures and cell-based assays with known neuronal cell-surface antigens were used. One hundred six patients with GAD65-abs and no cancer served as control individuals.Eight of the 15 patients with cancer presented as classic paraneoplastic syndromes (5 limbic encephalitis, 1 paraneoplastic encephalomyelitis, 1 paraneoplastic cerebellar degeneration, and 1 opsoclonus-myoclonus syndrome). When compared with the 106 non-PNS cases, those with PNS were older (median age, 60 years vs 48 years; P?=?.03), more frequently male (60% vs 13%; P?<?.001), and had more often coexisting neuronal cell-surface antibodies, mainly against ?-aminobutyric acid receptors (53% vs 11%; P?<?.001). The tumors more frequently involved were lung (n?=?6) and thymic neoplasms (n?=?4). The risk for an underlying tumor was higher if the presentation was a classic PNS, if it was different from stiff-person syndrome or cerebellar ataxia (odds ratio, 10.5; 95% CI, 3.2-34.5), or if the patient had coexisting neuronal cell-surface antibodies (odds ratio, 6.8; 95% CI, 1.1-40.5). Compared with the current series, the 19 previously reported cases had more frequent stiff-person syndrome (74% vs 13%; P?=?.001) and better responses to treatment (79% vs 27%; P?=?.005). Predictors of improvement in the 34 patients (current and previously reported) included presentation with stiff-person syndrome and the presence of a thymic tumor.Patients with GAD-abs must be screened for an underlying cancer if they have clinical presentations different from those typically associated with this autoimmunity or develop classic PNS. The risk for cancer increases with age, male sex, and the presence of coexisting neuronal cell-surface antibodies.

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Central nervous system destruction mediated by glutamic acid decarboxylase-specific CD4+ T cells.

Publications

Central nervous system destruction mediated by glutamic acid decarboxylase-specific CD4+ T cells.

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