Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, representing the hepatic component of metabolic syndrome. It comprises a wide spectrum of histological alterations, from simple steatosis to non-alcoholic steatohepatitis. Since the long-term consumption of sucrose rich diets (SRD) has been shown to induce damage to hepatic tissue attributed to the generation of oxidative stress, our main objective was to evaluate the effects of systemic hemin treatment, known to induce cytoprotective HO-1 activity, on hepatic parameters of insulin resistant (IR) animals. For this purpose, male Wistar rats were randomly distributed into control (C) or SRD groups (30% sucrose in the drinking water over 12 weeks). Hemin (15 mg/kg/48h, ip) was administered during the last two weeks of treatment (H and SRD+H groups). Our results indicate that, compared to controls, rats fed a SRD present higher levels of glycaemia and triglyceridemia. Neither glycaemia nor the TG/HDLc index or PEPCK protein levels (assessed by western blot) were modified by hemin treatment, suggesting that this treatment does not affect the IR state of the animals. Nevertheless, hemin administration attenuated the
increases in lipoperoxide levels (TBARS), in the activities of antioxidant enzymes (such as catalase and SOD) and in apoptosis, assessed by the number of TUNEL positive cells, and the measurement of cleaved caspase-3 levels by western blot. This treatment also normalized the serum activity of alanine transaminase (ALT), a marker of liver damage that was augmented in the SRD group (p<0,05 vs. SRD). Immunohistochemical analysis of hepatic tissues showed an increased expression of ED1 (marker of phagocytic activity)in both SRD groups (SRD and SRD+H) while no significant changes in Iba1, a monocyte-derived cell marker (by immunofluorescence) or F4/80 (by western blot) between groups. We also demonstrated the co-localization of ED1 with CLEC4f, a specific marker for Kupffer Cells (KC) by confocal microscopy. HO-1 induction by hemin treatment was confirmed in the liver by western blot and confocal microscopy, where the signal was co-localized with IBA-1, indicating that HO-1 is induced in inflammatory cells. In conclusion, long term consumption of a sucrose rich diet causes an increased
accumulation of lipids in the liver (hepatic steatosis) and generates oxidative stress (OS), tissue inflammation and also cell death (apoptosis). Treatment with hemin induces HO-1 expression mainly in Kupffer cells, and significantly attenuates these effects of diet on the liver. As these resident macrophage cells are the main producers of cytokines we hypothesize that HO-1 induction, due to its antioxidant effect , attenuates inflammation, and hence prevents the progression of the hepatic disease.