Bariatric surgery for metabolic dysfunction-associated steatotic liver disease (MASLD): Current knowledge of mechanisms

Metabolic dysfunction-associated steatotic liver diseases (MASLD) encompass a spectrum of liver disorders primarily defined by hepatic steatosis and cardiometabolic risk factors. MASLD affects over 30% of the global adult population, representing a substantial risk for public health. MASLD can progress from simple steatosis to steatohepatitis (termed MASH) marked by inflammation and fibrosis, potentially leading to cirrhosis and liver cancer. Obesity has been identified as one of the leading risk factors for MASLD, fueling the concept that efficient anti-obesity therapy will halt MASLD progression. Bariatric surgery (also termed metabolic and bariatric surgery, MBS) has become a well-established intervention for class III obesity and class II obesity with comorbidities, offering significant and sustained weight loss. The common MBS procedures (e.g., Roux-en-Y gastric bypass and sleeve gastrectomy) were indeed found to improve MASLD by ameliorating hepatic steatosis, inflammation, fibrosis, and reducing cancer risk in patients with MASLD/MASH. These effects may go beyond a simple consequence of restricted dietary intake, as illustrated by a growing body of studies showing MBS-induced transcriptional program changes in the liver. Given the mounting evidence from preclinical research, clinical trials and advanced biotechnologies emerging in recent years, refined histological and cellular in-depth characterization in MBS-treated MASLD is anticipated. This review summarizes the current knowledge on the pathogenic and therapeutic effects of MBS on MASLD, with the hope of inspiring further mechanistic and translational studies.