AHR and fatty liver disease: In contrast, tryptophan-derived metabolites, tryptamine and indole-3-acetate (I3A), have shown anti-inflammatory effects on macrophages and hepatocytes via activation of the aryl hydrocarbon receptor (AhR), a key regulator of inflammation and lipid metabolism (24), which may inhibit hepatocyte lipogenesis and protect against the progression of liver steatosis.