microRNA15a/16-1对B细胞及其介导的炎症性肠病恶性转化的调控研究

Inflammatory bowel disease (IBD) increases the risk of colon cancer. Large amounts of cytokines and immune cells are enriched in intestine tissue, which is crucial in the non-resolving intestinal inflammation and it associated tumorigenesis. In our previous studies, we investigated the immune regulation by establishing the animal model of IBD associated cancer induced by azoxymethane (AOM) and dextran sulfate sodium salt (DSS), and found that the small non-coding RNAs--microRNA (miRNA), miR-15/16 functioned as important regulators. The results showed that deficiency of miR-15/16 in mice promoted the development of IBD associated cancer, with increased accumulation of B-lymphocytes in intestine tissue. Moreover, B-lymphocytes with miR-15/16 deficiency had increased cell activation and more TGF-beta secretion. These data indicates miR-15/16 may be function as a suppressor during IBD associated neoplastic transformation, and B cell was involved in this process. Therefore, this project is designed to investigate the key immune cells and molecules under the regulation of miR-15/16 on the transformation, and clarify the mechanism underlying by modulating the expression of miR-15/16 in B cell, performing B cell adoptive transfer, as well as using proteomics-and bioinformatics-associated techniques. This project may be provide the basics for controlling the inflammation and preventing IBD-associated colorectal cancer, and thereby improve the early diagnosis and prognosis of IBD transformation.

炎症性肠病是结肠癌的诱因之一，其中，免疫调节异常是介导炎症失控、进而诱导肿瘤发生的关键。为此，我们通过构建小鼠肠炎癌转化模型开展免疫调控研究，发现microRNA15a/16-1(miR-15/16)是一个关键调控分子，表现为：1) miR-15/16缺陷促进小鼠肠炎癌转化；2) miR-15/16缺失上调肠道B细胞的比例，促进其在肠道内富集；3) miR-15/16缺失后B细胞活力增强，TGF-β分泌增加。提示，miR-15/16在肠炎癌转化中具有负向调控作用，且与B细胞相关。因此，本项目拟利用miR-15/16和B细胞敲除鼠，联合miR-15/16体内外过表达，B细胞体内过继转输及功能检测，生物信息预测及蛋白质组学分析等技术方法，进一步明确miR-15/16调控的关键免疫细胞及分子，解析其在肠炎癌转化中的具体作用及机制，期望为有效控制炎症反应的强度、缓解肿瘤发生，提供理论和实验依据。

炎症性肠病是结肠癌的诱因之一，其中免疫调节异常是介导炎症失控、进而诱导肿瘤发生的关键。通过构建小鼠肠炎癌转化模型，开展免疫调控研究，我们首次发现microRNA15a/16-1（MIR15A/16-1）是一组调控炎症相关肿瘤进展的的关键分子。MIR15A/16-1簇在结肠炎相关的结直肠癌进展过程中持续下调表达，其下调可促进B细胞在肠组织局部富集，促进肿瘤发生进展。进一步对B细胞的分析证实，B细胞介导了MIR15A/16-1簇对肠炎向肠肿瘤转化的调控作用，局部富集的B细胞上调IgA，IgA+B 细胞具有免疫抑制性，其高表达抑制性分子PD-L1、IL-10、TGFB，可抑制 CD8+T 的杀伤效应，促进肠癌的发生发展。机制分析证实MIR15A/16-1通过靶向IKKs-STAT1/p65信号轴抑制恶性转变的肠上皮细胞分泌CXCL9/10, 从而抑制对免疫抑制性B细胞的招募，缓解肿瘤。此外，持续性肠道炎症导致IL-6、IL-17A等炎症因子在局部大量积累，是促使MIR15A/16-1簇失调表达的关键诱因。研究结果拓展了miRNA在免疫调节方面的基础理论，较为新颖性地提出B细胞的免疫抑制性及其介导肿瘤发生发展的重要作用，可能做为后期炎症相关肠肿瘤防治的重要靶细胞，后期我们将积极尝试基于MIR15A/16-1簇和B细胞的应用转化。