晚期氧化蛋白产物通过上调PTHrP诱导小肠上皮细胞EMT在肠纤维化的作用及机制研究

Intestinal fibrosis (IF), related to intestinal stricture and obstruction, is a common complication in chronic intestinal diseases including inflammatory bowel diseases (IBD). The pathological mechanism underlying fibrotic strictures remain elusive. It is currently in a broad agreement that accumulation of extracellular matrix, synthesized by myofibroblasts under the stimuli of inflammatory factors, contributes to the development of IF. Intestinal epithelial cells, with epithelial-mesenchymal transition (EMT), are a major origin of myofibroblasts. Recent studies including our study verified that advanced oxidation protein products (AOPP) aberrantly accumulated in plasma and diseased tissues of patients with IBD, and caused intestinal cell death and injury, which suggested that AOPPs may play a role in IBD. Preliminary experiment further demonstrated that AOPP can cause an accumulation of Collagen Ⅰ and upregulate the expression of parathyroid hormone related protein (PTHrP), the latter having an interaction with the introduction of EMT. Therefore, we speculate that AOPP can induce EMT through upregulating the PTHrP expression, and thus impact the development of IF. Following work: (1) indentify whether AOPP induce EMT in intestinal epithelial cells (IECs); (2) explore the molecular mechanism underlying the EMT triggered by AOPP. Our study will clarify the pathological mechanism of IF by treatment or blockade of AOPPs, thus providing a new way to prevention and treatment of IF and a new view of the pathogenic effect of oxidation protein products.

小肠纤维化（IF）所致肠狭窄、肠梗阻是炎症性肠病等疾病的常见并发症。其发病机制尚不明确，多认为是炎症因子的释放激活成肌纤维细胞，大量生成细胞外基质所致。小肠上皮细胞(IEC)上皮间质转化（EMT）是成肌纤维细胞的重要来源。本课题组及其他研究者证实晚期氧化蛋白产物（AOPP）在炎症性肠病患者血清中升高及病变组织中沉积，并促IEC凋亡和损伤，提示AOPP参与炎症性肠病的进展。预实验证明AOPP促进IEC合成I型胶原并上调甲状旁腺激素相关蛋白（PTHrP）的表达，而后者可促EMT发生。因此，我们推测AOPP通过上调PTHrP诱导小肠EMT，参与IF的发病，这可能是IF的新机制。我们将研究：①AOPP诱导小肠上皮细胞EMT的作用；②通过抗体封闭、siRNA等分析AOPP诱导小肠EMT的膜受体及信号转导机制。本课题将从新的视角阐明IF的发病机制及为其防治提供新思路，并为AOPP的致病作用提供新信息。

小肠纤维化(IF)所致肠狭窄、肠梗阻是炎症性肠病等疾病的常见并发症，其发病机制尚不明确，通常认为是炎症因子释放激活成肌纤维细胞并大量产生细胞外基质所致。小肠上皮细胞（IEC）间质转化(EMT)并活化为成肌纤维细胞，是小肠纤维化的关键重要事件。本课题组围绕IEC的EMT核心问题在临床病理及体内外实验多个层面分别开展了PTHrP的致病性以及AOPP、PTHrP对小肠上皮细胞EMT作用的研究并针对其中的分子机制进行了深入详实的探讨。证明了AOPP及PTHrP均具有诱导小肠上皮细胞EMT作用，继而促进IF的发生发展，即AOPPs通过活化PKC δ-NADPH氧化酶途径，诱导NADPH氧化酶依赖的ROS生成，激活下游的NF-κB p65信号通路，最终诱导小肠上皮细胞EMT的发生。PTHrP通过激活PKA-Runx2信号通路诱导小肠上皮细胞的EMT。此外我们的实验还证实了PTHrP经与PTH1R受体结合，激活肝内胆管癌细胞ERK/JNK-ATF2-CyclinD1信号通路，促进肝内胆管癌细胞的增殖分化作用。本研究进一步揭示了AOPPs及PTHrP的致病性，并从新的视角阐明了IF发生发展的机制，为IF的预防与治疗提供了新的理论基础、新的干预靶点及其可能的手段方式。