Obesity-Induced MASLD Is Reversed by Capsaicin via Hepatic TRPV1 Activation.

BACKGROUND AND OBJECTIVES: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive liver disorder associated with metabolic risk factors such as obesity, type 2 diabetes, and cardiovascular disease. If left untreated, the accumulation of excess hepatic fat can lead to inflammation, fibrosis, cirrhosis, hepatocellular carcinoma, and ultimately liver failure. Capsaicin (CAP), the primary pungent compound in chili peppers, has previously been shown to prevent weight gain in high-fat diet (HFD)-induced obesity models. In this study, we investigated the potential of dietary CAP to prevent HFD-induced MASLD. METHODS: C57BL/6 mice were fed an HFD (60% kcal from fat) with or without 0.01% CAP supplementation for 26 weeks. We evaluated CAP's effects on hepatic fat accumulation, inflammation, and mitochondrial function to determine its role in preventing MASLD. RESULTS: CAP acts as a potent and selective agonist of the transient receptor potential vanilloid 1 (TRPV1) channel. We confirmed TRPV1 expression in the liver and demonstrated that CAP activates hepatic TRPV1, thereby preventing steatosis, improving insulin sensitivity, reducing inflammation, and enhancing fatty acid oxidation. These beneficial effects were observed in wild-type but not in TRPV1 knockout mice. Mechanistically, CAP-induced TRPV1 activation promotes calcium influx and activates AMPK, which leads to SIRT1-dependent upregulation of PPARα and PGC-1α, enhancing mitochondrial biogenesis and lipid metabolism. CONCLUSIONS: Our findings suggest that dietary CAP prevents MASLD through TRPV1 activation. TRPV1 signaling represents a promising therapeutic target for the prevention and management of MASLD in individuals with metabolic disorders.