Bruton's Tyrosine Kinase and Immune Tolerance in Type 1 Diabetes

 描述(申请人提供)：1型糖尿病(T1D)是由一系列复杂的事件引起的，这些事件破坏了免疫耐受，最终导致胰岛细胞的破坏。B淋巴细胞(B细胞)在疾病中起关键作用。这个项目的重点是中央B细胞信号蛋白，布鲁顿的酪氨酸激酶(BTK)的作用。我们已经确定了BTK在支持向自身反应性T细胞递呈抗原的自身反应性B细胞中的作用，并表明BTK可以靶向保护T1D的发展。我们现在将这些发现扩展到粘膜免疫，并发现BTK缺陷的非肥胖糖尿病(NOD)小鼠大大减少了Peyer‘s Patch B细胞的数量，这是产生IgA的重要因素。相应地，IgA也降低了。因此，我们测试了肠道粘膜中的IgA选择驻留微生物的假设。肠道微生物区系的基因测序显示，与野生型NOD鼠相比，BTK-/-/NOD鼠的微生物种群发生了显著变化。此外，在BTK-/-/NOD小鼠中，在新生儿期暴露于不同的微生物取消了对疾病的保护。这一提议背后的假设是，通过BTK的B细胞信号支持IgA的产生，IgA形成一个微生物组，在遗传敏感的宿主中促进T1D。为了了解BTK对微生物组的贡献与T1D的关系，我们建议：1)确定BTK调节微生物组的机制，使用细胞特异性的靶向缺失来定义对肠道免疫结构的影响，包括Peyer氏斑。将研究BTK作用对IgA产生和肠道免疫反应的影响，并评估BTK抑制剂对粘膜免疫的影响；2)确定BTK靶向修饰微生物组的动力学。当微生物群对BTK的功能敏感时，将确定从新生儿到成人的发育阶段。定时切除BTK或给药将评估阻止NOD模型中T1D进展的可能性，并确定是否需要微生物组修饰才能获得成功的结果。实验还将确定PP B细胞的重组如何影响微生物修饰和疾病结果，以及3)确定BTK支持的微生物群对疾病的贡献。BTK-/-/NOD小鼠将被重新培养成无菌设施，以将BTK信号的自身免疫性疾病效应与微生物组的影响分开。粪便转移将用于直接测试微生物群对T1D的贡献。该项目对于了解BCR信号如何支持影响T1D结局的共生菌群的选择具有直接的临床意义，这是开发治疗干预措施的必要步骤。

 DESCRIPTION (provided by applicant): Type 1 diabetes (T1D) results from a complex cascade of events that breaks immune tolerance and culminates in the destruction of islet ß cells. B lymphocytes (B cells) play a critical role in disease. This project focuses on the role ofa central B cell signaling protein, Bruton's tyrosine kinase (BTK). We have defined the role of BTK in supporting autoreactive B cells that present antigen to autoreactive T cells, and shown that BTK can be targeted to protect against development of T1D. We now extend those findings to mucosal immunity, and have discovered that BTK-deficient nonobese diabetic (NOD) mice have greatly reduced numbers of Peyer's Patch B cells, important for production of IgA. Accordingly, IgA is also reduced. We therefore tested the hypothesis that IgA in gut mucosa selects the resident microbes. Genetic sequencing of intestinal microbiota showed that Btk-/-/NOD mice have strikingly altered microbial populations compared with wild type NOD mice. Furthermore, exposure to different microbes in the neonatal period abrogated disease protection in Btk-/-/NOD mice. The hypothesis underlying this proposal is that B cell signaling via BTK supports production of IgA, which shapes a microbiome that promotes T1D in genetically susceptible hosts. To understand BTK contributions to the microbiome in relationship to T1D, we propose to: 1) determine the mechanisms by which BTK regulates the microbiome, by using cell-specific targeted deletion to define the effects on gut immune structures including Peyer's Patches. The impact of BTK actions on IgA production and gut immune responses will be investigated and effects of BTK inhibitors on mucosal immunity assessed, 2) determine the kinetics of BTK-targeting in modifying the microbiome. The developmental stages from neonate to adult when the microbiome is sensitive to the functions of BTK will be identified. Timed excision of BTK or drug administration will assess the potential to halt the progression of T1D in the NOD model and determine if microbiome modification is required for a successful outcome. Experiments will also determine how reconstitution with PP B cells affects microbial modification and disease outcome, and 3) determine disease contributions of the microbiome that is supported by BTK. Btk-/-/NOD mice will be rederived into a germ-free facility to separate autoimmune disease effects of BTK-signaling from that of the microbiome. Fecal transfer will be used to directly test microbiome contributions to T1D. This project has direct clinical importance in understanding how BCR-signaling supports the selection of commensal flora that influences the outcome of T1D as a necessary step in developing therapeutic interventions.