SRA介导胆囊粘膜下泡沫细胞形成在胆囊胆固醇沉积中的作用机制研究

30% of the cholesterol gallstone patients had cholesterolosis in the gallbladder, which is characterized as mucosal villous hyperplasia with excessive accumulation of cholesterol esters within epithelial macrophages. However，the underlying mechanism remains unclear. Our preliminary study found foam cells accumulation could be found in mucosa from patients with gallstone disease which was associated with high expression of inflammatory molecule scavenger receptor A (SRA) and pro-inflammatory cytokine IL-1β. Moreover, the formation of gallstone and cholesterolosis could be ameliorated in SRA knockout mice fed with lithogenic diet. We hypothesized that SRA mediated inflammatory response in the gallbladder mucosa in response to cholesterol supersaturated bile might be one of the key mechanism to induce formation of cholesterolosis. In this project, we will 1) to verify the inflammatory cell infiltration and molecular expression of inflammatory factors in gallbladder mucosa from patients with cholesterol gallstone disease; 2) to determine the role of inflammatory response in foam cell formation in mice fed with lithogenic diet under conditions of SRA knockout or SRA inhibitor treatment; 3) to study the interaction between gallbladder epithelium cell and macrophages in response to cholesterol supersaturated bile and the induction of cholesterol accumulation and foam cell formation. The results of our study will provide some important experimental evidences for the mechanism of cholesterolosis during gallstone formation as well as its prevention so as to protect of gallbladder function.

约30%胆囊胆固醇结石患者胆囊粘膜存在不同程度胆固醇沉积，表现为泡沫细胞形成，与大量脂质沉积有关，但其形成机制尚未明了。前期研究显示，胆石病人胆囊粘膜有不同程度的泡沫细胞集聚，与先天免疫相关受体-清道夫受体A（SRA）高表达和促炎症介质IL-1β增多相关。成石饲料喂养SRA基因敲除小鼠则延缓胆石形成和粘膜胆固醇沉积。据此假设胆固醇过饱和胆汁启动胆囊粘膜SRA介导的炎症反应是泡沫细胞形成及胆固醇沉积的关键机制。本项目拟研究：临床样本验证胆囊粘膜炎症细胞浸润和分子表达激活状态；分别利用SRA基因敲除小鼠以及抑制剂证明该分子介导的炎症反应对胆囊粘膜胆固醇沉积的影响；通过胆囊上皮细胞和巨噬细胞共培养，探讨过饱和胆固醇激活炎症反应引起巨噬细胞吞噬胆固醇并沉积形成泡沫细胞的机制。旨在通过抑制胆囊粘膜下炎症，防治胆固醇沉积，保护胆囊功能提供重要的理论和实验依据。

本项目首先研究了SRA在小鼠成石中的作用发现，成石过程中肝脏及胆囊上皮SRA表达增加，伴随肝脏胆固醇增加、胆汁胆固醇分泌增多以及胆囊内胆固醇沉积，对SRA参与成石提供了实验依据。进而研究阐明饮食节律改变导致的肝脏胆固醇、胆汁酸代谢节律变化具有促进结石形成的作用。采用植物甾醇通过抑制肠道胆固醇吸收对于胆结石形成具有较好的预防作用。最后还发现，胆囊切除后可影响肠道菌群谱以及肠壁通透性，在高脂饮食下，具有促进脂肪肝形成的影响。