Kynurenine plays an immunosuppressive role in 2,4,6-trinitrobenzene sulfate-induced colitis in mice

Figure 5 Administration of Kyn improved TNBS-induced colitis. KMO^+/+ and KMO^−/− mice were treated with the indicated KP metabolites 12 h after TNBS injection, and the colons were collected on day 3. A: Histological inflammation scores for the colons of KP metabolite-treated mice or PBS-treated mice. B: Representative images of H&E-staining in the colon of indicated mice. C: The ratios of Foxp3⁺ Treg cells to total CD4⁺ T cells in the colons of mice. D: Serial sections of the colons of from indicated mice were stained for Foxp3 and counterstained with hematoxylin, allowing indication of Foxp3⁺ cells. E: The mRNA expression levels of TGF-β and IL-10 were determined by quantitative PCR. The data are represented as mean ± SE from at least four independent experiments: ^aP < 0.05 vs PBS-treated KMO^−/− mice group; ^bP < 0.01 vs PBS-treated KMO^+/+ mice group. KMO: Kynurenine 3-monooxygenase; TNBS: Trinitrobenzene sulfonic acid; Kyn: Kynurenine; KA: Kynurenic acid; AA: Anthranilic acid; 3-HK: 3-hydroxykynurenine; 3-HAA: 3-hydroxyanthranilic acid; TGF-β: Transforming growth factor-β; IL-10: Interleukin-10; Foxp3: Forkhead boxprotein P3.