To determine whether IL-17 deficit-related gut dysbiosis influences the function of the intestinal barrier and explore the mechanism in the NAFLD/NASH process, we used a methionine choline-deficient (MCD) diet to induce a model of NAFLD/NASH, which results in severe NASH with significant hepatic inflammation and fibrosis. The gene discussed is IL17A; the disease is metabolic dysfunction-associated steatohepatitis.