Hepatoprotective effect of cinnabarinic acid in metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH) is an advanced form of metabolic dysfunction-associated steatotic liver disease (MASLD) characterized by accumulation of fats in liver, chronic inflammation, hepatocytic ballooning, and fibrosis. This study investigates role of endogenous Aryl hydrocarbon Receptor (AhR) agonist, cinnabarinic acid (CA) in protection against in vivo mouse model of MASH. To analyze the transcriptomic changes in response to CA treatment, male AhRfl/fl (AhR-floxed) mice were subjected to control diet (CD), high-fat high-fructose high-cholesterol diet (MASH diet, MD), and fed with MASH diet and treated with CA thrice a week for 20-week period. RNA sequencing revealed altered expression of multiple genes involved in fatty acid metabolism and inflammation in response to CA treatment. Gene set enrichment analysis indicated enrichment of AMPK among other kinases. Subsequent immunoblotting and immunofluorescence studies performed on CA-treated livers and primary hepatocytes confirmed activated AMPK signaling. Moreover, in a hepatocyte-specific AhR knockout mice livers (AhR-hKO, constructed by crossing AhRfl/fl with alb-Cre), CA failed to phosphorylate AMPK strongly indicating that CA-induced AMPK mediated protection against lipotoxicity in MASH is dependent on hepatic AhR signaling.