TNFRSF9 and ulcerative colitis: AMK polysaccharide  • Inhibited body weight loss and colon length shortening• Restored colon tissue architecture• Normalized goblet cells• Increased fecal and plasma AhR ligands (Iald, ILA, PA, and Trp) and plasma Ser and 5-HTAAMechanism of AMK polysaccharide in treating ulcerative colitis is associated with increasing AhR ligands in the feces and plasma.