MicroRNA-155/SHIP-1通路在克罗恩病肠黏膜对肠腔共生菌群免疫耐受缺失中的角色

Crohn's disease, which presented as intestinal chronic inflammation, was considered as the results from uncontrolled immune response due to the lake of tolerance to luminal commensal microbiota. It was recently reported that SHIP-1, whose production was directly regulated by microRNA-155, played an important role in the immune tolerance, additionally, microRNA-155 was also found to be associated with autoimmune diseases. However, limited data about the microRNA-155/ SHIP-1 related to the pathogenesis of Crohn's disease. We previously found the decreased expression of SHIP-1 protein in the gut mucosa of Crohn's disease animal model. To further explore the pivotal role played by microRNA-155/SHIP-1 pathway in the loss of tolerance to commensal microbiota by gut mucosa with Crohn's disease, we hereby proposed a study focused on the microRNA-155/SHIP-1 pathway in CD mouse model and CD patients intestinal dendritic cells performed in vivo and in vitro, by molecular biology and immuno technology techniques. Further more,by regulation of the miRNA-155,the effects of microRNA-155/SHIP-1 pathway on the intestinal inflammation will also be explored. The result of our study may add some information for the understanding of the pathogenesis of CD and provide some therapeutic implications for the treatment of this an incurable intestinal disorder.

目前认为克罗恩病（CD）是由于肠黏膜免疫耐受缺失导致的黏膜-肠腔共生菌群异常作用而引起的肠道慢性炎症。研究发现SHIP-1在调节免疫耐受中起重要作用，作为SHIP-1调控因子的microRNA-155也参与多种免疫相关疾病，但microRNA-155/ SHIP-1通路在CD黏膜免疫中的作用尚不明确。我们前期研究发现CD模型小鼠出现SHIP-1蛋白的低表达，提示microRNA-155/ SHIP-1通路可能参与CD的病理生理过程，但具体机制尚需深入研究。在前期工作基础上，本课题以CD模型小鼠和CD患者肠组织为研究对象，通过分子生物学以及分子免疫学等技术，着眼于肠黏膜树突状细胞，以miR-155/SHIP-1为切入点，通过在体与离体调控miRNA-155的表达，探讨miR-155/SHIP-1通路在CD肠黏膜免疫耐受缺失中的角色，以期为揭示CD的发病机制提供依据、为CD临床防治提供靶点。

机体-细菌相互间的异常作用是克罗恩病肠道炎症的重要因素之一。肠黏膜对肠道共生菌免疫耐受缺失，表现为对肠道内微生物及外来抗原出现不可控制的、持续的炎症反应，从而导致肠道组织的损伤，是克罗恩病发病的核心机制。miR-155/SHIP-1通路在免疫耐受调控中起到重要的作用。我们推测miR-155/SHIP-1通路可能在克罗恩病肠黏膜免疫耐受缺失中起到重要的作用。为验证这一假设，本课题以克罗恩病模型小鼠和克罗恩病患者肠黏膜树突状细胞为研究对象，采用在体研究和离体实验相结合的手段，通过免疫组化、分子生物学以及分子免疫学等技术，探讨miR-155/SHIP-1通路在克罗恩病肠黏膜免疫耐受缺失中的角色，探索以miR-155为靶点调控miR-155/SHIP-1通路、抑制肠道炎症、治疗克罗恩病的意义，以期为克罗恩病的发病机制与临床防治提供实验依据及治疗靶点。..本课题研究结果表明：相对于无菌环境，饲养于共生菌存在的无特定病原菌（SPF）环境的克罗恩病模型小鼠（IL-10-/-小鼠）产生结肠炎时其miR-155表达显著增加，而SHIP-1的表达则相对降低。在克罗恩病模型小鼠中，外源性予以miR-155反义寡核苷酸能够抑制miR-155的表达，从而增加SHIP-1的表达，达到免疫耐受的作用，减轻肠道炎症。而过表达miR-155能够显著SHIP-1蛋白的表达，增加肠道炎症反应。取自克罗恩病患者的树突状细胞（DC）miR-155表达显著增加，而SHIP-1蛋白的表达则明显降低。基因沉默miR-155能够显著增加克罗恩病患者树突状细胞SHIP-1的表达，并显著抑制之炎因子的表达。而过表达miR-155则明显抑制SHIP-1的表达，增加之炎因子的表达。表明调节miR-155能够通过SHIP-1影响树突状细胞对克罗恩病肠黏膜免疫稳态起到调控作用。