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

 描述（由申请人提供）：1型糖尿病（T1 D）是由破坏免疫耐受并最终破坏胰岛β细胞的复杂级联事件引起的。B淋巴细胞（B细胞）在疾病中起关键作用。本项目的重点是中枢B细胞信号蛋白布鲁顿酪氨酸激酶（BTK）的作用。我们已经确定了BTK在支持将抗原呈递给自身反应性T细胞的自身反应性B细胞中的作用，并表明BTK可以被靶向以防止T1 D的发展。我们现在将这些发现扩展到粘膜免疫，并发现BTK缺陷型非肥胖糖尿病（NOD）小鼠的派伊尔集合淋巴结B细胞数量大大减少，这对伊加的产生很重要。因此，伊加也减少了。因此，我们测试的假设，伊加在肠道粘膜选择的居民微生物。肠道微生物群的基因测序显示，与野生型NOD小鼠相比，Btk-/-/NOD小鼠的微生物群发生了显著改变。此外，在新生儿期暴露于不同的微生物会消除Btk-/-/NOD小鼠的疾病保护作用。 这一提议背后的假设是，通过BTK的B细胞信号传导支持伊加的产生，IgA形成了在遗传易感宿主中促进T1 D的微生物组。为了了解BTK对与T1 D相关的微生物组的贡献，我们提出：1）通过使用细胞特异性靶向缺失来确定对肠道免疫结构（包括派尔集合淋巴结）的影响，确定BTK调节微生物组的机制。将研究BTK作用对伊加产生和肠道免疫应答的影响，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。将确定微生物组对BTK功能敏感的从新生儿到成人的发育阶段。BTK的定时切除或药物施用将评估在NOD模型中阻止T1 D进展的潜力，并确定是否需要微生物组修饰以获得成功的结果。实验还将确定用PP B细胞重建如何影响微生物修饰和疾病结果，以及3）确定由BTK支持的微生物组的疾病贡献。Btk-/-/NOD小鼠将被重新衍生到无菌设施中，以将BTK信号传导的自身免疫性疾病效应与微生物组的自身免疫性疾病效应分开。粪便转移将用于直接测试微生物组对T1 D的贡献。 该项目在理解BCR信号传导如何支持选择影响T1 D结局的植物植物群方面具有直接的临床重要性，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.