炎症性肠病（IBD）是免疫相关的肠道炎症疾病，发病机制尚不清楚。研究表明microRNA155（miR155）表达变化可调控树突状细胞（DC）的功能，我们的预实验发现DC选择性miR155过表达转基因鼠（CD11c-miR155KI）与野生型小鼠相比，IBD发病时炎症明显加重。据此推测：DCmiR155的表达变化可使肠道DC亚群"重新编程"，内部信号分子发生改变，促使DC在IBD发病中介导T细胞应答类型发生变化，最终导致疾病发生。本项目以现代免疫学方法结合CD11c-miR155转基因和基因缺陷鼠模型为实验平台，深入探讨IBD发病中miR155调控肠道DC亚群的分子机理和信号通路，分析肠道DC亚群miR155表达变化对IBD发病的作用机制。本研究有助于深刻理解miR155调控的肠道DC亚群在IBD中的作用，以阐明炎症性肠病等自身免疫性疾病的发病机理，为开发出新型免疫调节药物提供理论依据。

Intestinal inflammation in inflammatory bowel disease(IBD)is characterized by a dysregulated intestinal immune response, initiation and perpetuation of inflammation in experimental colitis by mechanism has not been known. In our preliminary study, we found that bone marrow derived CD11c-miR155KI mice dendritic cell(DC) which cultured in vitro showed spontaneous maturation compared to WT, and increased ability to stimulate T cell activation and proliferation, the ratio of CD11bhiDC subset in the spleen and mesenteric lymphoid node was dramatically decreased. CD11c-miR155KI mice showed a substantial weight loss and its colitis inflammation was more servious in the process of IBD. Accordingly we made the scientific hypothesis as follows: Because of over-expression or deficient of miR155, intestinal DC can be reprogrammed a new DC subset, intracellular molecules in DC will be alterated, these reactions will result in that the ability of DC polarizing T cell response will be changed. In this study, we will do experiments with CD11c-miR155KI or miR155-deficient mice model to address the role of miR155 in the development and function of enteric DC by virtue of modern immunological techniques. Further study will confirm the effect of enteric DC subsets which are different with the change of miR155 expression on the development IBD as a colitis model. The study will contribute to understand deeply the role of intestinal DC which regulated by miR155 expression in IBD, to elucidate the underlying pathogenesis of autoimmue diseases such as IBD. It will provide a protential and theoretical basis for exploiting new immunoregulatory drug in the future.