IL-23/Th17介导的微炎症通过损伤肠上皮屏障参与艰难梭菌感染复发的机制研究

Clostridium difficile (C.difficile) is the most common opportunistic pathogen in clinical practice, and approximately 30% of C.difficile infection (CDI) experience disease recurrence. However, the underlying mechanism has not been fully elucidated. Previous study demonstrated that micro-inflammation of mucosal mediated by IL-23/Th17 might associated with CDI recurrence. Our previous study also discovered that Inflammatory cytokines may induce the shedding of syndecan-1, and destroy the tight junction of intestinal epithelial cells by activating the Sdc1/Src-Stat3 pathway, leading to impairment of intestinal epithelial barrier. Therefore, we come up with a novel hypothesis that micro-inflammation mediated by IL-23/Th17 might contribute to CDI recurrence via Sdc1/Src-Stat3-TJ pathway. This study aims to test this hypothesis by establishing IL-23 gene knockout mice model and regulating Sdc1/Src-Stat3 pathway by specific inhibitors and renti-virus infection, to investigate whether micro-inflammation mediated by IL-23/Th17 contributes to CDI recurrence via Sdc1/Src-Stat3 pathway in vivo and in vitro, so as to elucidate potential mechanism for CDI recurrence and provide novel target for treatment of CDI reccurence.

艰难梭菌（C.difficile）是临床最常见的机会致病菌, 约30%的艰难梭菌感染（CDI）复发，其机制尚未明确。既往有研究认为：发生CDI后，低水平的IL-23可能通过Th17细胞介导微炎症反应，参与CDI复发。我们的前期研究发现：炎症因子可通过刺激Sdc1胞外段脱落，激活Sdc1/Src-Stat3通路，破坏上皮紧密连接（TJ），导致肠上皮屏障受损。因此我们推测： IL-23/Th17介导的微炎症可能通过激活Sdc1/Src-Stat3通路损伤肠上皮屏障，促进CDI复发。本项目旨在验证这一假说。拟采用IL-23基因敲除小鼠构建CDI恢复模型，进一步通过特异性抑制剂及慢病毒转染等技术调控Sdc1/Src-Stat3通路活化，在体内和体外探讨IL-23/Th17介导的微炎症是否通过Sdc1/Src-Stat3通路参与CDI复发，以阐明CDI复发机制，为防治CDI复发提供新思路及干预靶标。

艰难梭菌（Clostridium difficile）是临床最常见的机会致病菌, 约30%的艰难梭菌感染（Clostridium difficile infection，CDI）患者发生复发，但其机制尚未明确。既往有研究认为：发生CDI后，低水平的IL-23可能通过Th17细胞介导微炎症反应，参与CDI复发。基于以上背景，本项目科学假说为： IL-23/Th17介导的微炎症可能通过激活Sdc1/Src-Stat3通路损伤肠上皮屏障，促进CDI复发。本研究成功采用IL-23基因敲除小鼠，建立稳定的CDI复发（RCDI）小鼠模型，研究结果表明，与野生型C57小鼠发生RCDI相比，IL-23敲基因鼠发生RCDI时，疾病状态明显好转，肠上皮屏障受损情况明显减轻，Scd1表达水平升高，致炎因子水平明显下降。同时我们发现RCDI发生时Src/Stat3通路激活，给予小鼠STAT3特异性抑制剂AG490，可明显抑制艰难梭菌感染复发，而IL-23敲基因鼠发生RCDI时，该条通路激活水平较野生型小鼠发生RCDI时也有所下降。进一步给予RCDI小鼠Th17特异性转录因子RORrt抑制剂SR1001，结果发现，SR1001可提高肠上皮屏障蛋白表达，明显改善RCDI小鼠疾病状态。本研究结果表明IL-23/Th17介导的微炎症可通过Sdc1/Src-Stat3通路参与CDI复发，为防治CDI复发提供了新思路及干预靶标。