基于肠系膜脂肪细胞转变探讨脂联素在克罗恩病肠道纤维化的作用及机制研究

The intestinal fibrosis is one of challenging problems in clinical treatment of Crohn’s disease (CD), and there is no effective treatment nowadays. Mesenteric fat-wrapping is considered as one of the hallmarks of CD，with the change of adipocyte type. Our previous studies indicated that mesenteric fat-wrapping possess potential predicting ability to identify the site of inflammatory in intestine, while its role on inflammatory and fibrosis remains unclear. Moreover, we found that the expression of adiponectin (APN) decreased significantly in CD fibrosis intestine in our previous animal experiments. Most of APN originates from mesentery and acts as an anti-fibrosis factor which can influence the crinical pathway of fibrosis----TGF-beta/Smad signaling pathway. Therefore, we speculate that mesenteric fat wrapping can affect intestinal fibrosis through APN and this signaling pathway. Based on the previous work, we further validate the relationship between immune micro-environment mediated by ANP and TGF-beta/Smad signaling pathway, explore the mechanism that APN affect the occurrence and development of CD fibrosis and provide further theoretical evidence and experimental foundation for the treatment of CD fibrosis.

肠道纤维化是克罗恩病（CD）临床治疗的难题之一，目前尚无有效治疗手段。肠系膜脂肪增厚是CD的特征性表现之一，伴随着脂肪细胞类型的转变。前期研究发现，肠系膜脂肪增厚对肠道炎症部位具有良好的指示作用，但其在肠道炎症以及纤维化的作用及相关机制尚不明确。同时，我们前期在动物实验中发现CD纤维化肠道的脂联素（APN）表达水平显著下降。脂联素主要来源于肠系膜组织，并作为一种抗纤维化因子可作用于纤维化的主要通路——TGF-β/Smad信号通路。因此我们推测：肠系膜脂肪增厚通过APN调节TGF-β/Smad信号通路从而影响CD肠道纤维化。本研究将在前期工作的基础上，进一步验证APN调控的免疫微环境因子以及与TGF-β/Smad信号通路的作用，探索APN影响CD纤维化发生发展的机制，为CD纤维化的临床治疗提供进一步的理论依据和实验基础。

肠纤维化是克罗恩病 (CD) 的常见并发症。据报道，脂联素在各种疾病模型中发挥抗炎作用，包括结肠炎模型。在本研究中，我们旨在确定脂联素对肠纤维化的影响及其潜在机制。通过灌肠给予Balb/c小鼠递增剂量的2,4,6-三硝基苯磺酸7周，建立小鼠肠纤维化模型。从 CD 患者的结肠组织中分离出原代人成纤维细胞。将成纤维细胞与转化生长因子（TGF）-β1一起孵育以建立体外纤维化模型。通路抑制剂用于验证参与脂联素抗纤维化作用的潜在信号通路。与正常肠系膜相比，CD患者肥大肠系膜脂联素表达明显升高。腹腔注射脂联素显着降低了纤维化模型小鼠结肠髓过氧化物酶活性和促炎细胞因子（肿瘤坏死因子α和白细胞介素6）的表达，而抗炎细胞因子白细胞介素10的表达显着增加。此外，脂联素治疗可抑制模型小鼠的结肠缩短、结肠重量减少和纤维化蛋白沉积减少。脂联素降低了原代人肠成纤维细胞中 Smad2 的磷酸化和由 TGF-β1 诱导的胶原沉积，同时增加了 AMP 活化蛋白激酶 (AMPK) 的磷酸化。此外，这种现象被 AMPK 抑制剂逆转。脂联素可通过增强AMPK磷酸化和抑制TGF-β1/Smad信号通路活性来预防肠纤维化。