Breaking the barriers: the role of gut homeostasis in Metabolic-Associated Steatotic Liver Disease (MASLD)

Obesity, insulin resistance (IR), and the gut microbiome intricately interplay in Metabolic-associated Steatotic Liver Disease (MASLD), previously known as Non-Alcoholic Fatty Liver Disease (NAFLD), a growing health concern. The complex progression of MASLD extends beyond the liver, driven by "gut-liver axis," where diet, genetics, and gut-liver interactions influence disease development. The pathophysiology of MASLD involves excessive liver fat accumulation, hepatocyte dysfunction, inflammation, and fibrosis, with subsequent risk of hepatocellular carcinoma (HCC). The gut, a tripartite barrier, with mechanical, immune, and microbial components, engages in a constant communication with the liver. Recent evidence links dysbiosis and disrupted barriers to systemic inflammation and disease progression. Toll-like receptors (TLRs) mediate immunological crosstalk between the gut and liver, recognizing microbial structures and triggering immune responses. The "multiple hit model" of MASLD development involves factors like fat accumulation, insulin resistance, gut dysbiosis, and genetics/environmental elements disrupting the gut-liver axis, leading to impaired intestinal barrier function and increased gut permeability. Clinical management strategies encompass dietary interventions, physical exercise, pharmacotherapy targeting bile acid (BA) metabolism, and microbiome modulation approaches through prebiotics, probiotics, symbiotics, and fecal microbiota transplantation (FMT). This review underscores the complex interactions between diet, metabolism, microbiome, and their impact on MASLD pathophysiology and therapeutic prospects.