Figure 1.

Tryptophan metabolism is altered in murine and human colitis. A: Relative levels of indole metabolites in serum and whole colon tissue of mice receiving either water or 3% dextran sodium sulfate (DSS) for 7 days. Metabolites were measured by liquid chromatography–mass spectrometry and gas chromatography–mass spectrometry analysis. B: Condensed pathway of tryptophan metabolism to indole and indole derivatives. C: EC-HPLC analysis of indole metabolites in serum of mice receiving either water or 2.5% DSS for 9 days. D: Concentrations of indole metabolites in serum of mice receiving either water or 2.5% DSS for 9 days. E: Indole-3-propionic acid (IPA) levels in serum samples from healthy controls (Con), subjects with active ulcerative colitis (UC), and subjects with UC in remission (Rem) profiled by EC-HPLC. Data are expressed as means ± SEM (A, D, and E). n = 5 (A, mice per treatment group, and D, water treatment); n = 10 (D, DSS treatment); n = 20 (E, control and remission); n = 15 (E, UC). ^∗P < 0.05, ^∗∗P < 0.01, t-test and one-way analysis of variance. IAld, indole-3-aldehyde.