Regulation of normal human IEL by NKG2D and IL-15

描述(由申请人提供)：最近的进展揭示了IL-15和NKG2D/MIC相互作用在人体肠道上皮内细胞溶解T淋巴细胞(IEL)水平上连接先天免疫和获得性免疫的关键作用。NKG2D识别应激诱导的肠上皮细胞表面MHC编码的MICA和B分子，并通过Dap 10接头介导直接细胞溶解功能，增强TCR介导的效应功能和增殖。IL-15是IEC产生的一种细胞因子，启动了NKG2D/Dap10信号通路的多个步骤。最近的报道证实，NKG2D的异常激活参与了自身免疫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，支持了该通路在非感染性免疫病理学中的重要性。这一建议扩展了我们对CD94/NKG2、NKG2D和IL-15在IEL中的早期研究，在分子水平上剖析了正常IEL中NKG2D表达、转运和信号转导的机制以及IL-15对它们的协调调节。具体目标1将描述直接细胞溶解的NKG2D信号。我们将利用KK特异性抑制物、显性负性KK和缺乏KK的细胞系，研究NKG2D介导的参与细胞溶解的信号通路。特定目标2将表征NKG2D的循环和降解，因为表面NKG2D在配体结合时下调严格控制NKG2D的激活。具体目标3将剖析IL-15和组蛋白脱乙酰酶(HDAC)调节NKG2D的分子和生化基础。我们的初步数据表明，IL-15上调HDAC，HDAC在NKG2D的合成和降解中发挥作用。总之，这些研究将剖析IEL中的NKG2D信号通路，以及IL-15对NKG2D表达和功能的显著生理影响的机制。这些结果可能为新的治疗方法提供基础，例如使用HDAC抑制剂来治疗自身免疫性和炎症性疾病，如乳糜泻、类风湿性关节炎和1型青少年糖尿病，在这些疾病中，NKG2D和IL-15的异常表达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.