Discipline of Medicine and the Bosch Institute, NSW 2006, Australia.
J Hepatol. 2011 Aug;55(2):435-44. doi: 10.1016/j.jhep.2010.10.039. Epub 2010 Dec 22.
BACKGROUND & AIMS: While type 2 diabetes is an independent risk factor for worsening of human non-alcoholic steatohepatitis (NASH) in clinical studies, it has not been systematically reported in any model whether diabetes exacerbates NASH. The study aim was to determine if diabetes causes NASH progression in a mouse model of diet induced obesity.
C57BL/6 mice were fed a high fat diet (HFD: 45% kcal fat) or standard chow (CHOW: 12% kcal fat) for 20 weeks and some animals (HFD+DM or CHOW+DM) were also rendered diabetic by low dose streptozotocin for the final 5 weeks, to model type 2 diabetes. Serum assays included circulating insulin, triglyceride, ALT and AST, glucose, and ultrasensitive CRP and results of insulin tolerance tests. Intrahepatic lipid, triglyceride, macrophage infiltration, and fibrosis were determined. Fibrosis markers collagen-I, collagen-III, CTGF, TIMP-1, and FAP were assessed by qPCR and CTGF and collagen-I by immunostaining.
HFD mice were obese, insulin resistant and hyperinsulinaemic, with NASH features of elevated intrahepatic lipid and macrophages, but without fibrosis. In contrast, the HFD+DM mice exhibited fibrosis in addition to these NASH features. By ANOVA, Sirius red staining at perisinusoidal, portal tract and central vein sites, collagen-I, collagen-III, FAP, and TIMP-1 transcripts and collagen-I and CTGF protein were each significantly increased in HFD+DM, compared with CHOW alone. In a further experiment, insulin treatment protected against fibrosis and CRP increases in HFD+DM, showing that diabetes, not streptozotocin, causes the fibrosis.
This novel model indicates that diet-induced NASH fibrosis is exacerbated by diabetes and attenuated by insulin therapy.
在临床研究中，2 型糖尿病是人类非酒精性脂肪性肝炎（NASH）恶化的独立危险因素，但在任何模型中都没有系统报道糖尿病是否会加重 NASH。本研究旨在确定糖尿病是否会在饮食诱导肥胖的小鼠模型中导致 NASH 进展。
C57BL/6 小鼠喂食高脂肪饮食（HFD：45%卡路里脂肪）或标准饲料（CHOW：12%卡路里脂肪）20 周，一些动物（HFD+DM 或 CHOW+DM）在最后 5 周也通过低剂量链脲佐菌素诱导糖尿病，以模拟 2 型糖尿病。血清检测包括循环胰岛素、甘油三酯、ALT 和 AST、葡萄糖和超敏 CRP，以及胰岛素耐量试验的结果。测定肝内脂质、甘油三酯、巨噬细胞浸润和纤维化。通过 qPCR 评估纤维化标志物胶原-I、胶原-III、CTGF、TIMP-1 和 FAP，通过免疫染色评估 CTGF 和胶原-I。
HFD 小鼠肥胖、胰岛素抵抗和高胰岛素血症，伴有肝内脂质和巨噬细胞升高的 NASH 特征，但无纤维化。相比之下，HFD+DM 小鼠除了这些 NASH 特征外还出现了纤维化。通过方差分析，在窦周、门脉区和中央静脉区的天狼星红染色、胶原-I、胶原-III、FAP 和 TIMP-1 转录物以及胶原-I 和 CTGF 蛋白在 HFD+DM 中均显著高于 CHOW 单独组。在进一步的实验中，胰岛素治疗可预防 HFD+DM 中的纤维化和 CRP 升高，表明是糖尿病而不是链脲佐菌素导致了纤维化。
本新型模型表明，饮食诱导的 NASH 纤维化在糖尿病的作用下加重，并可通过胰岛素治疗减轻。
