基于Exosome反应性B细胞过继免疫探讨边缘区B细胞在1型糖尿病发病机制中的作用

因B细胞免疫耐受的破坏而激活自身反应性T细胞是1型糖尿病的重要发病机制之一。前期研究发现兼有固有免疫细胞样特征的边缘区B细胞具有选择和放大致病性T细胞的效应。目前对其自身活化机制仍然不明。Exosomes （外吐小体，EXOs)是一种新型的细胞分泌囊泡，参与细胞间的信号传递和病理生理过程。EXOs不但能够激活边缘区B细胞释放IL-6、TNFα等炎症细胞因子，还因为携带自身抗原而特异性的激活引起糖尿病的自身反应性B和CD4+ T细胞，所以EXO反应性B细胞为研究1型糖尿病提供了新的靶点。我们拟采用细胞培养、流式细胞术、杂交瘤技术等方法对EXO反应性B细胞进行表型和抗原特异性鉴定；利用B细胞重建NOD.Ignull小鼠糖尿病模型，体内验证EXO反应性B细胞在糖尿病中的作用；同时借助转基因动物明确MDA5固有免疫通路在活化边缘区B细胞中不可或缺的作用。为1型糖尿病的诊断、预防和治疗开辟新途径。

The early breach of B cell tolerance and sequential induction of autoreactive T cells are major contributors to type 1 diabetes (T1D). Our prior data found that marginal zone B (MZ B) cells，with innate like lymphocyte function, were effective in activating and expanding the autoreactive T cells. Their antigen receptors are cross-reactive to many different self antigens but with low affinity. The mechanism how MZ B cells contribute to autoimmunity remains unclear. Exosomes (EXOs) are nano-sized vesicles secreted by different kinds of cells, whose function is mainly to act as a cell-to-cell messenger, but also believed to mediate pathophysiology. Upon EXO stimulation, MZ B cells can release proinflammatory cytokines such as IL-6, TNFα. Moreover, autoantigens carried by the EXOs can stimulate EXO-specific autoreactive B and T cells. Therefore, EXO reactive B cells provide us a novel tool for the investigation of type 1 diabetes. In this study, we attempt to adopt cell culture, flow cytometry, and hybridoma techniques to analyze the phenotype of the EXO-induced B cells, and study their antigenic specificity.To confirm the T1D-causative role of the B cells, we will perform cell adoptive transferring experiments via B cell reconstitution in NOD.Ignull mice. Meanwhile, we will study EXO-induced innate response in the activation of MZ B via MDA5 pathway by using knockout mice, which may shed new light on the diagnosis, prevention and therapy of T1D.