Regulation of normal human IEL by NKG2D and IL-15

描述（由申请人提供）：最新进展揭示了IL-15和NKG 2D/MIC相互作用在人肠道上皮内溶细胞性T淋巴细胞（IEL）水平上连接先天性和适应性免疫中的关键作用。NKG 2D识别肠上皮细胞（IEC）表面应激诱导的MHC编码的MIC A和B分子，并通过Dap 10衔接子发出信号，以介导直接细胞溶解功能并增强TCR介导的效应子功能和增殖。IL-15是IEC产生的一种细胞因子，可启动NKG 2D/Dap 10信号通路的多个步骤。最近的报告已经确定，NKG 2D激活失调参与了自身免疫性和炎症性疾病的发病机制，如乳糜泻、类风湿性关节炎和I型自身免疫性糖尿病，支持了该途径在非感染性免疫病理学中的重要性。这一建议扩展了我们早期对IEL中CD 94/NKG 2、NKG 2D和IL-15的研究，以在分子水平上剖析正常IEL中NKG 2D表达、运输和信号传导的潜在机制以及IL-15对其的协调调节。特定目的1将表征直接细胞溶解的NKG 2D信号传导。使用激酶特异性抑制剂、显性负性激酶和激酶缺陷细胞系，我们将研究参与细胞溶解的NKG 2D介导的信号通路。具体目标2将表征NKG 2D再循环和降解，因为配体结合后的表面NKG 2D下调严格控制NKG 2D活化。具体目标3将剖析IL-15和组蛋白脱乙酰酶（HDAC）调节NKG 2D的分子和生化基础。我们的初步数据表明，IL-15上调HDAC，HDAC在NKG 2D合成和降解中发挥作用。总的来说，这些研究将剖析IEL中的NKG 2D信号通路以及IL-15对NKG 2D表达和功能的显著生理效应的潜在机制。这些结果可以为使用例如HDAC抑制剂的新型治疗方法提供基础，用于自身免疫性和炎性疾病，例如乳糜泻，类风湿性关节炎和1型青少年糖尿病，其中NKG 2D和IL-15的表达失调起着重要的致病作用。

DESCRIPTION (provided by applicant): Recent advances have revealed the critical role of IL-15 and NKG2D/MIC interactions in linking innate and adaptive immunity at the level of intraepithelial cytolytic T lymphocytes (IEL) in the human intestine. NKG2D recognizes the MHC-encoded MIC A and B molecules induced upon stress at the surface of intestinal epithelial cells (IEC) and signals through the Dap 10 adaptor to mediate direct cytolytic functions and enhance TCR-mediated effector functions and proliferation. IL-15, a cytokine produced by IEC, primes multiple steps of the NKG2D/Dap10 signaling pathway. Recent reports have established that dysregulated activation of NKG2D is involved in the pathogenesis of autoimmune and inflammatory disorders, such as celiac disease, rheumatoid arthritis and type I autoimmune diabetes, supporting the importance of this pathway in noninfectious immunopathology. This proposal extends our earlier studies of CD94/NKG2, NKG2D and IL-15 in IEL to dissect at the molecular level the mechanisms underlying NKG2D expression, trafficking and signaling in normal IEL and their coordinated regulation by IL-15. Specific aim 1 will characterize NKG2D signaling for direct cytolysis. Using kinase specific inhibitors, dominant negative kinases, and kinase-deficient cell lines we will study the signaling pathways mediated by NKG2D that are involved in cytolysis. Specific aim 2 will characterize NKG2D recycling and degradation, as surface NKG2D downregulation upon ligand engagement tightly controls NKG2D activation. Specific aim 3 will dissect the molecular and biochemical basis for NKG2D regulation by IL-15 and Histone deacetylases (HDAC). Our preliminary data suggest that IL-15 upregulates HDACs and that HDACs play a role in NKG2D synthesis and degradation. Collectively, these studies will dissect the NKG2D signaling pathways in IEL and the mechanisms underlying the striking physiological effects of IL-15 on NKG2D expression and function. The results may provide the basis for novel therapeutic approaches, using for example HDAC inhibitors, for autoimmune and inflammatory diseases such as celiac disease, rheumatoid arthritis and type 1 juvenile diabetes, where dysregulated expression of NKG2D and IL-15 plays an important pathogenic role.