Abstract: Objective To investigate the effect of 1-deoxynojirimycin (DNJ) for improving diabetic liver fibrosis and explore the underlying mechanism. Methods Mouse models of type 2 diabetes were established in 10 Kunming mice by high-fat diet feeding for 8 weeks and intraperitoneal injection of STZ, with 5 mice receiving intraperitoneal injection of citrate buffer solution with normal feeding as the control group. The mouse models were randomized into two groups (n=5) for further high-fat feeding (model group) and additional treatment with 10% DNJ in drinking water (200 mg · kg- 1 per day; DNJ group) for 8 weeks. The mice were monitored for changes in body weight (BW), blood glucose, serum total cholesterol (TC), triglyceride (TG) and superoxide dismutase (SOD) levels. The pathological changes in the liver tissue were observed using HE and Sirius Red staining, and the solubility of collagens in the liver tissues was determined. The expression levels of MCP-1, TNF-α, IL-1β and TGF-β1 mRNA were detected with real-time PCR, and the protein expressions of α-SMA and collagen2 (ColA2) were determined with Western blotting. In the in vitro experiment, mouse fibroblasts L929 cells were pretreated with DNJ (10 μg/ mL) or PBS for 30 min followed by culture in high-glucose medium for 24 h, and the level of ROS production was measured using dihydroethidium (DHE) staining. Results In the mouse model of type 2 diabetes, DNJ treatment significantly lowered serum level of glucose, TC, and TG (P<0.05) and increased serum SOD activity (P<0.05). DNJ obviously attenuated liver fibrosis in the diabetic mice, as shown by alleviated cross-linking of collagens and reduced contents of pepsin-solubilized collagen (PSC) and total collagen (P<0.05). DNJ treatment also significantly reduced the overexpression of the pro-inflammatory cytokines and fibrosis-related cytokines induced by diabetes (P<0.05). In L929 cells exposed to high glucose, pretreatment with DNJ significantly lowered the intensity of red fluorescence in DHE staining. Conclusion DNJ can attenuate type 2 diabetes-induced liver fibrosis in mice through its hypoglycemic, anti-inflammatory and anti-oxidative effects.

Key words: type2 diabetes; hepatic fibrosis; 1-deoxynojirimycin; collagen cross-linking; oxidative stress