In an experimental model using rats (Sprague Dawley) transplanted with fecal microbiota (FMT) from healthy and IBS-positive patients, as well as those administered with berberine (200 mg/kg), hyperplasia in the liver of Kupffer cells (liver macrophages) and hepatic sinusoid hypertrophy were observed, along with elevated levels of proinflammatory hepatic cytokines such as TNF-α and IFN-β. This evidence concerns the gene IFNB1 and irritable bowel syndrome.