Nitro-fatty acids protect against steatosis and fibrosis during development of nonalcoholic fatty liver disease in mice

Lack of non-invasive diagnostic tools and effective therapies constitute two of the major hurdles for a bona fide treatment against non-alcoholic steatohepatitis (NASH) progression and/or regression of nonalcoholic fatty liver disease (NAFLD). Nitro-oleic acid (OA-NO2) has been proven effective in multiple experimental models of inflammation and fibrosis. Thus, the potential benefit of in vivo administration of OA-NO2 to treat advanced NAFLD was studied in a model of long-term NASH diet-induced liver damage. Non-invasive imaging (e.g. photoacustic-ultrasound (PA-US)) was pursued to establish advanced experimental NASH in mice in which both steatosis and fibrosis were diagnosed prior experimental OA-NO2 therapy. CLAMS and NMR-based analysis demonstrates that OA-NO2 improves body composition and energy metabolism and inhibits hepatic triglyceride accumulation. PA-US imaging revealed a robust inhibition of liver steatosis and fibrosis by OA-NO2. RNA-sequencing analysis uncovered inflammation and fibrosis as major pathways suppressed by OA-NO2 administration, as well as regulation of lipogenesis and lipolysis pathways, with a robust inhibition of SREBP1-dependent lipogenic gene expression by OA-NO2. Global liver transcriptome in response to OA-NO2 was confirmed in vivo and in isolated hepatocytes. These results were further supported by histological analysis and quantification of lipid accumulation, lobular inflammation (F4/80 staining) and fibrosis (collagen deposition, aSMA staining) as well as established parameters of liver damage (ALT). In vitro studies indicate that OA-NO2 inhibits TG biosynthesis and accumulation in hepatocytes and inhibits fibrogenesis in human stellate cells. Taken together, OA-NO2 improve steatohepatitis and fibrosis and may constitute an effective therapeutic approach against advanced NAFLD that warrants further clinical evaluation. Overall design: C57BL/6J mice were fed standard chow diet (CD) or NASH-diet rich in saturated fat, trans-fat, fructose and cholesterol (40% of calories from fat, Research Diets D17010103) for 24 weeks. All mice were maintained on a 12-hour light/dark cycle and had ad libitum access to food and water. Mice were subjected to subcutaneous implantation of osmotic minipumps for delivery of polyethylenglycol (PEG), PEG-solvated oleic acid (OA), or PEG-solvated OA-NO2 at an infusion rate of 5 mg/kg/day.

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Rom O, Xu G, Guo Y, Zhu Y, Wang H, Zhang J, Fan Y, Liang W, Lu H, Liu Y, Aviram M, Liu Z, Kim S, Liu W, Wang X, Chen YE, Villacorta L