细胞外基质蛋白Tenascin C 在腹膜透析患者腹膜纤维化的作用及机制研究

Peritoneal fibrosis, which is characterized by interstitial fibrosis, is one of the important implications in long-term peritoneal dialysis. In our preliminary study, we generated a TNC-CreER-eGFP transgenic mouse and found that TNC and fibroblasts was induced remarkably in the glucose-induced peritoneal fibrosis. The tissue fibrosis was alleviated remarkably when the TNC gene was knocked out. Thus, we suppose that exposed to the high glucose, TNC secreted by the mesenchymal cells could bind to the EGFR of fibroblasts and induce cell proliferation, transdifferentiation and secretion, resulting in the peritoneal fibrosis. To validate the hypothesis, we will use the TNC knockout and report mouse, and then establish the high glucose-induced peritoneal fibrosis models. We will verified the role of TNC in peritoneal fibrosis using the cell tracing and molecular biology techniques, and further explore the potential mechanisms of TNC promoting peritoneal fibrosis. Our study is of great significance in understanding the mechanism of ECM impacting on fibroblasts in peritoneal fibrosis, and more importantly, these findings will be valuable for finding novel therapeutic targets of peritoneal fibrosis.

腹膜纤维化是长期腹膜透析患者所面临的重要并发症，目前对其发生发展的机制认识尚不完全，缺乏有效的预防、治疗手段。我们前期研究发现细胞外基质蛋白Tenascin C（TNC）在高糖诱导的腹膜纤维化中表达明显增加、表达TNC的成纤维细胞明显增加。TNC基因缺失可明显减轻组织纤维化程度。因此，我们假设在高糖刺激下，腹膜间质细胞转分化分泌TNC，TNC通过作用于成纤维细胞表面EGFR，进一步促进成纤维细胞增殖、转分化等介导腹膜纤维化。本研究将采用TNC敲除、TNC报告小鼠，建立高糖诱导腹膜纤维化模型，应用细胞跟踪等技术，探讨TNC在腹膜纤维化发生发展中的作用，并进一步探讨TNC在这一过程中可能的作用机制。该研究对探讨腹透患者腹膜纤维化中成纤维细胞转分化和增殖的机制、对探寻防治腹膜纤维化的新靶点具有重要价值。

在我国，慢性肾脏病患者人数已超1亿人，终末期肾脏并患病率亦逐年升高。在我国，腹膜透析是重要的肾脏替代治疗方案之一，然而，长期的腹膜透析过程中，高渗透析液反复刺激腹膜组织，导致腹膜纤维化增厚，可产生晚期糖基化产物等物质，导致腹膜间质纤维化、血管增生等生理病理过程的发生，引起超滤衰竭、毒素清除率降低、甚至包裹硬化性腹膜炎(EPS)等严重并发症，最终被迫退出腹膜透析治疗乃至威胁患者生命。.本课题应用TNC-CreER-eGFP 转基因小鼠及TNC-CreER-eGFP，td-Tamo双转基因小鼠，在高渗腹透液刺激下(4.25%PD4 连续腹腔注射4周），通过病理染色及免疫荧光发现小鼠腹膜组织明显增厚，同时伴有α-SMA及Col I表达增高,伴有TNC表达明显增加，表达TNC的细胞数量亦明显增多，而在敲除TNC小鼠腹膜纤维化模型中（TNC-cre+/-及TNC-cre+/+小鼠）水平较野生型小鼠明显减轻。同时在腹膜透析患者中，患者血清TNC水平在随访期间较基线水平亦有明显升高，提示在腹膜透析过程中，随着透析液对腹膜的持续刺激，患者体内表达TNC的水平亦有所增加，TNC血清水平情况可能间接反映腹膜组织损伤情况。然而，在血清TNC与总CCR、腹透CCR及残肾CCR的线性相关性分析中，未见明显统计学差异。.本研究结果提示，TNC在腹膜纤维化过程中发挥重要作用，阻断其表达，可减轻腹膜纤维化，为预防、治疗腹膜纤维化提供了新方向、新策略。