Kupffer细胞极化和肝星状细胞活化在NAFLD相关炎症和纤维化中的作用

Roles of Kupffer Cell Polarization and Hepatic Stellate Cell Activation in Hepatic Inflammation and Fibrosis in NAFLD

背景:Kupffer细胞和肝星状细胞(HSC)在慢性肝损伤炎症和纤维化的始动和持续过程中发挥重要作用。目的:研究非酒精性脂肪性肝病(NAFLD)进展中Kupffer细胞极化和HSC活化对肝内炎症-纤维化发展的影响。方法:分别以高脂(HF)饮食和蛋氨酸胆碱缺乏(MCD)饮食诱导C57BL/6小鼠非酒精性脂肪肝(NAFL)和非酒精性脂肪性肝炎(NASH)模型。HE染色和Masson染色评估肝脏组织病理学改变,免疫组化染色检测Kupffer细胞表型和HSC活化状态,real-time PCR检测炎症、纤维化相关基因和PPAR-γ表达。结果:HF和MCD饮食诱导的小鼠NAFL和NASH模型肝内F4/80阳性Kupffer细胞、CD11c阳性M1型巨噬细胞和α-SMA阳性HSC均较对照组明显增加(P<0.05),MCD组增加更为显著(P<0.05)。NAFL和NASH时肝内TNF-α、TGF-β1 mRNA表达均显著增高(P<0.05),α-SMA、Col1 mRNA表达仅在NASH时显著增高(P<0.05)。肝内PPAR-γmRNA表达在NAFL时显著增高(P<0.05),在NASH时则显著降低(P<0.05)。结论:在NAFLD进展过程中,肝内Kupffer细胞呈现持续的M1型极化,HSC在疾病早期已出现活化并随疾病由NAFL向NASH进展而加剧。Kupffer细胞极化和HSC活化促进了NAFLD中肝脏炎症-纤维化的启动和进展。

Background:Kupffer cells and hepatic stellate cells(HSC)play important roles in the initiation and progression of hepatic inflammation and fibrosis in chronic liver injury.Aims:To investigate the roles of Kupffer cell polarization and HSC activation in the development of hepatic inflammation and fibrosis in progression of non-alcoholic fatty liver disease(NAFLD).Methods:C57BL/6 mice were fed with high fat(HF)diet and methionine-choline-deficient(MCD)diet to induce experimental non-alcoholic fatty liver(NAFL)and non-alcoholic steatohepatitis(NASH),respectively.Liver steatosis,inflammation and fibrosis were determined by histopathological examination through HE staining and Masson staining.Kupffer cell phenotypes and HSC activation were assessed by immunohistochemistry.Expressions of PPAR-γas well as inflammation-and fibrosis-related genes were measured by real-time PCR.Results:F4/80-positive Kupffer cells,CD11c-positive M1 polarized macrophages andα-SMA-positive HSC were significantly increased in liver tissue of mice with HF diet-induced NAFL and MCD diet-induced NASH(P<0.05),and was more apparent in MCD diet-induced NASH(P<0.05).Expressions of TNF-αand TGF-β1 mRNA in liver tissue were significantly increased in both groups(P<0.05),whereas expressions ofα-SMA and Col1 mRNA were significantly increased only in NASH(P<0.05).Hepatic PPAR-γmRNA expression was significantly increased in NAFL(P<0.05)but significantly decreased in NASH(P<0.05).Conclusions:Hepatic Kupffer cells exists a sustained M1 polarization in the development of NAFLD.Activation of HSC appears in the early stage of NAFLD,and accelerates in the progression of NAFL to NASH.Polarization of Kupffer cells and activation of HSC initiate and promote hepatic inflammation and fibrosis in NAFLD.