TL1A在炎症性肠病相关肠纤维化中的作用与机制研究

The intestinal stricture or obstruction resulting from intestinal fibrosis is a common complication of IBD. The central event of intestinal fibrosis is the activation and proliferation of intestinal fibroblasts caused by inflammatory factors from the inappropriate and exaggerated mucosal immune disorder with susceptibility gene, which can result in greater collagen deposition. The latest studies have proven that TL1A, a recruit of tumor necrosis factor super family, may mediate immune responses to promote intestinal inflammation while combined with its receptor DR3, which was the initial agent of intestinal fibrosis. Consequently, our hypothesis is that TL1A is correlated with intestinal fibrosis, intervening in TL1A by neutralizing anti-TL1A antibody may be a new target to reverse intestinal fibrosis. In this study, TNBS-induced chronic colitis intestinal fibrosis model will be established using LCK-CD2-TL1A-GFP Tg mice and wild type (WT) mice to investigate the effects of anti-TL1A antibody on intestinal fibrosis.The correlation of TL1A expression and intestinal fibrosis will be analyzed, the immunoregulatory role of TL1A in the pathogenesis of gut fibrosis will be observed by checking cytokines'expression of immune cells. Moreover, we will also study the influences of TL1A on activation, proliferation, apoptosis and collagen metabolism of both mouse primary intestinal fibroblasts (IFBs) and human CCD-18Co cell line to investigate the role of TL1A in signal transduction mechanism of gut fibrosis. This study may provide a new research evidence on the pathogenesis and the effective prevention and therapeutic strategy of IBD-associated intestinal fibrosis.

肠纤维化所致肠腔狭窄、肠梗阻是炎症性肠病（IBD）常见并发症。其发生是在易感基因基础上，出现肠黏膜免疫失调，释放炎症因子刺激肠成纤维细胞活化、增殖，从而导致大量胶原沉积所致。最新研究证实，肿瘤坏死因子超家族新成员TL1A，作为IBD易感基因，可通过与其受体DR3结合介导免疫反应促进肠道炎症发生。而炎症是肠纤维化发生的始动因素，因此，我们推测TL1A与肠纤维化有关，干预TL1A可能成为逆转肠纤维化的新靶点。本研究分别采用TL1A转基因和野生型小鼠，建立TNBS慢性结肠炎肠纤维化模型，并应用抗TL1A抗体进行干预，分析TL1A与肠纤维化发生的相关性；检测免疫细胞相关因子的变化，探讨TL1A调控肠纤维化的免疫机制；同时以小鼠原代肠成纤维细胞和人结肠CCD-18Co为研究对象，观察TL1A对细胞增殖、凋亡及胶原代谢的影响，为揭示IBD相关肠纤维化发病机制、寻求有效防治肠纤维化的新策略提供实验依据。

肠纤维化是IBD常见的严重并发症，可导致肠狭窄，甚至肠梗阻。肿瘤坏死因子1A是肿瘤坏死家族一员，研究证实TL1A作为IBD发病的易感基因通过激活T细胞发挥重要的促炎作用，据此推测对其阻断可能成为逆转IBD相关肠纤维化新靶点。本研究重点探索了TL1A在IBD及其并发肠纤维化中的作用。本研究应用LCK-CD2-TL1A-GFP转基因小鼠构建TNBS结肠炎模型和T细胞转移结肠炎模型，并给予预防性、治疗性抗TL1A抗体干预结肠炎小鼠，应用HE、天狼猩红、麻松染色检测肠道组织病理及纤维化改变，应用免疫组织化学、western、PCR检测肠道炎症因子、胶原蛋白表达、成纤维细胞活化，并进一步研究TGFβ/Smad3信号通路表达情况。结果显示，TL1A过表达通过增加白介素17、TNF-α、IFN-γ分泌从而促进了肠道炎症反应，进一步激活肠道成纤维细胞分泌胶原蛋白并影响胶原代谢进而导致肠纤维化形成，应用抗TL1A抗体阻断后则减轻肠道炎症反应，阻断肠道成纤维活化，减少胶原合成达到抑制肠炎后肠纤维化改变，，其发挥作用可能与TGFβ/Smad3的信号通路有关，并且预防性应用抗TL1A抗体效果优于治疗性应用。研究TIL1A在炎症性肠病相关肠纤维化中的作用可能为探索有效的治疗方法提供新的研究证据。