非酒精性脂肪性肝病在动脉粥样硬化发生发展中的作用

目的探讨非酒精性脂肪性肝病在动脉粥样硬化发生发展中的作用。方法 64只SD大鼠随机分为正常对照组及高糖高脂组,每组再分3、6、9个月和12个月4个时段进行观察,每时段8只。对照组喂饲基础饲料,高糖高脂组喂饲高糖高脂饲料。放射免疫法及酶联免疫吸附实验测定外周血中丙氨酸氨基转移酶、游离脂肪酸、甘油三酯、总胆固醇、高密度脂蛋白、低密度脂蛋白、血糖、空腹胰岛素及内毒素、肿瘤坏死因子、C反应蛋白、单核细胞趋化蛋白1、一氧化氮、内皮素1的水平;摘取主动脉及肝脏组织观察病理形态学变化;CD68免疫组织化学染色单核巨噬细胞观察其在动脉壁的浸润情况;苏丹Ⅳ特殊染色观察脂质在动脉壁的异位沉积情况;Tunnel免疫组织化学染色观察内皮细胞及平滑肌细胞的凋亡情况。结果高糖高脂组大鼠甘油三酯、外周血总胆固醇、低密度脂蛋白、丙氨酸氨基转移酶及空腹血糖、空腹胰岛素水平均升高,且内毒素、C反应蛋白、肿瘤坏死因子α、单核细胞趋化蛋白1、内皮素1水平也明显升高,而高密度脂蛋白和一氧化氮水平明显降低;高糖高脂组大鼠3个月时即发生了脂肪肝、非酒精性脂肪性肝炎,此时动脉内皮表面出现单核细胞黏附,且内皮细胞出现散在凋亡现象;6个月时肝脏出现纤维化,动脉内皮下脂质明显沉积,单核细胞在斑块内浸润,粥样斑块形成;同时动脉内皮及平滑肌细胞的凋亡明显加重;9个月时肝脏纤维化进一步加重,动脉壁粥样斑块内大量单核细胞浸润,部分斑块出现钙盐沉积,大部分内皮及平滑肌细胞发生凋亡;12个月时肝脏发展为早期肝硬化,动脉壁粥样斑块大片钙盐沉积,内皮及平滑肌细胞发生广泛且弥漫凋亡。结论高糖高脂膳食可诱发非酒精性脂肪性肝病,并伴有肠源性内毒素血症及脂代谢紊乱和慢性炎症的发生。肠源性内毒素血症直接或间接引起内皮细胞受损及功能紊乱,启动动脉粥样硬化的发生,并随着脂质异位沉积及单核细胞浸润,加剧动脉粥样硬化的发展。

Role of Nonalcoholic Fatty Liver Disease in the Mechanism of Atherosclerosis

Aim To investigate the relationship between pathogenesis of atherosclerosis and nonalcoholic fatty liver disease(NFLD). Methods 64 SD rats were randomly divided into two groups: normal control group with normal basic diet and high-sucrose and high-fat diet group with high sucrose and high fat diet.Each group was divided into four phases: 3 months,6 months,9 months and 12 months.Each phase had eight rats.Alanine aminotrnsferase,free fatty acid(FFA),triglyceride(TG),total cholesterol(TC),high density lipoprotein(HDL),low density lipoprotein(LDL),fasting plasm glucose(FPG),fasting insulin(FIN),and endotoxin(LPS),tumor necrosis factor-α(TNF-α),C-reaction factor(CRP),macrophagocyte chemotaxis protein-1(MCP-1),nitrc oxide(NO),endothelin-1(ET-1) were measured by ELISA;All the rats were killed and their livers and arterial specimens were taken to carry on HE stain for observing their histopathologic and morphologic change.Tunnel was used to detect the endothelial cell and smooth muscle cells apoptosis by immunohistochemistry.The expression of CD68 protein were detected by immunohistochemistry for observing mononuclear cells expression in aortic wall.Sudan IV stain was used to show whether ectopic lipid have accumulated in aortic wall.Results The level of TG,Ach,FFA,LDL,ALT,FIN,LPS,CRP,TNF-α,MCP-1,ET-1 in HSHF group was significantly increased and the level of HDL and NO was decreased(P < 0.050).Three-month-old rats had nonalcoholic fatty liver disease and fatty liver,at the same time several mononuclear cells adhered to the endothelial cells some of which appeard apoptosis.Fibrosis occurred at six-months-old rats and there was lipids under the endothelial cells,meanwhile,the apoptosis exacerbated obviously.The fibrosis became gradually serious in liver in 12-month-old group.It can be observed that calcium deposited in a lot of mononuclear cells in atherosclerotic plague.Apoptosis existed in endothelial cells and smooth muscle cells.Conclusions High-fat high-sucrose diet induces non-alcoholic fatty liver disease(NAFLD),accompanied by Intestinal Endotoxemia(IETM),disturbance of lipids metabolism and chronic inflammation.IETM further results in continuous endothelial dysfunction,ectopic deposition of lipids and local infiltration of mononuclear macrophages.This finally leads to As.