基于TSP1的线粒体调控作用探讨三七治疗溃疡性结肠炎大鼠肠黏膜微血管损伤的作用机制

Ulcerative colitis (UC) is characterized by chronic, recurrent ulcers and inflammation of the colonic mucosa. UC seriously influences the quality of life in patients. Moreover, people who have UC are at an increased risk of developing cancer. Although the pathogenesis of UC is not fully understood, the mucosal micro-vascular injuries(MVI) are considered as important initiating pathological changes in early UC.In the development of UC, the appearance of mucosal MVI is related to the up-regulation of TSP1 protein in colon tissue and the increasing abnormalities of mitochondrial structure and function in micro-vascular endothelial cell (mVEC). However, the mechanism that up-regulated TSP1 protein promotes MVI and the regulatory effect of mitochondrial disorders are still unclear. We suppose that the abnormalities of mitochondria induced by up-regulated TSP1 protein in mVEC is an important intermediate factor in the occurrence of colonic mucosal MVI in UC. In this study, we will observe the colonic MVI and mitochondrial abnormality in mVEC following up-regulated TSP1 protein, and explore the regulatory effect of TSP1 on mitochondrial structure and function，and the pathogenic role of mitochondrial disorders in the development of MVI in UC. Based on this, we will investigate the pharmacological effect of Panax Notoginseng(PN) on colonic mucosal MVI and the mechanisms involved.

溃疡性结肠炎（UC）以慢性、反复发作的结肠黏膜炎症与溃疡为特点，严重影响患者的生活质量，且有很高的癌变风险。尽管UC的发病机制尚不明确，但UC早期即出现的肠黏膜微血管损伤(MVI)被认为是UC的重要始发因素；且UC结肠黏膜MVI的发生与结肠细胞TSP1表达上调及微血管内皮细胞（mVEC）线粒体结构与功能异常密切相关。但TSP1表达上调导致MVI的作用机制及mVEC线粒体异常在MVI发生中的作用尚不清楚。我们推测：TSP1表达上调诱导mVEC线粒体异常可能是造成UC结肠黏膜MVI发生的重要中间因素。在本研究中，我们通过观测TSP1表达上调后UC结肠黏膜mVEC线粒体及微血管的改变，探索TSP1蛋白对mVEC线粒体结构和功能的调控作用及在诱导MVI发生中的作用，并在此基础上研究三七治疗UC结肠黏膜MVI的药理机制，进而阐释UC“瘀毒致病”学说以及中医“行血则便脓自愈”活血治法的现代生物学内涵。

溃疡性结肠炎（Ulcerative colitis，UC）以慢性、反复发作的结肠黏膜炎症与溃疡为特点，严重影响患者的生活质量，且有很高的癌变风险。尽管UC的发病机制尚不明确，但UC早期即出现的肠黏膜微血管损伤（Microvascular injuries, MVI）被认为是UC发病的重要始发因素；本研究中我们发现：UC大鼠肠黏膜微血管存在明显的损伤，且随着肠黏膜MVI的发生大鼠肠黏膜炎症损伤亦明显加重；且肠黏膜MVI严重程度与UC肠黏膜组织中TSP1蛋白水平密切相关。进一步研究发现：TSP1蛋白可以显著诱导血管内皮细胞凋亡，抑制血管管腔形成。且其作用机制与TSP1蛋白的表达升高显著增加肠黏膜血管内皮细胞内糖酵解有关。但可惜的是在本实验中并未发现TSP1蛋白可显著减少血管内皮细胞内线粒体数量。反而TSP1蛋白表达增加可显著增加大鼠肠黏膜血管周围巨噬细胞浸润，促进肠黏膜微血管周围炎症。其调控机制与TSP1蛋白抑制巨噬细胞内溶酶体活性及糖氧化，诱导巨噬细胞极化异常有关。中药三七可以有效促进UC大鼠结肠黏膜及MVI的修复，降低血清促炎因子水平，升高抑炎因子水平。深入研究发现：三七可通过显著下调结肠组织TSP1蛋白表达，改善肠黏膜微血管周围浸润巨噬细胞内溶酶体活性，减轻巨噬细胞极化异常，改善肠黏膜组织细胞内糖代谢，促进肠黏膜微血管损伤修复。肠黏膜MVI及巨噬细胞溶酶体功能异常可认为是UC“瘀毒”的微观体现之一，因而本研究结果从一定程度上阐释了UC“瘀毒致病”学说以及中医“行血则便脓自愈”活血治法的现代生物学内涵。