To investigate the effects of tumor necrosis factor-related ligand-1A (TL1A) on activation of T helper 9 (Th9) cells of colonic tissues in chronic experimental colitis mice.

The chronic experimental colitis mice model was established with drinking dextran sulfate sodium salt (DSS). A total of 32 lymphocytes TL1A highly expressed mice and wild type (WT) mice were divided into WT control group, transgene control group, WT modeling group and transgene modeling group. The mice of control groups were administrated with distilled water. The mice of modeling groups received 3% DSS in drinking water discontinuously. The mice were sacrificed on 29 days after modeling. Body mass was measured, length of colon was recorded, scores of gross colon and the disease activity index (DAI) were calculated. The colonic morphological changes were observed by hematoxylin-eosin (H-E) staining. The lamina propria mononuclear cells (LPMC) were isolated and the number of Th9 cells was tested by flow cytometry. The levels of interleukin-9 (IL-9) in serum and LPMC were detected by enzyme-linked immunosorbent assay (ELISA). The expressions of IL-9 protein and mRNA of the colonic tissues were measured by Western blotting and real-time polymerase chain reaction (PCR), respectively. T test and single factor analysis of variance were performed for statistical analysis.

The percentage of body mass loss of WT modeling group was lower than that of transgene modeling group (16.2%±1.0% vs 18.9%±1.2%), and the difference was statistically significant (t=4.90, P<0.05). The scores of gross colon, DAI and pathology of transgene modeling group were all higher than those of WT modeling group (2.80±0.64 vs 1.60±0.31, 2.55±0.20 vs 1.58±0.17, and 11.85±0.86 vs 9.50±0.79), and the differences were statistically significant (t=4.77, 10.45 and 5.69, all P<0.05). The number of LPMC in transgene modeling group was higher than that of WT modeling group (3.70×10⁶±0.28×10⁶ vs 2.65×10⁶±0.32×10⁶) and the difference was statistically significant (t=6.98, P<0.05). The percentage of Th9 in total CD4⁺ T cells of LPMC in colonic tissues of transgene modeling group was higher than that of WT modeling group (0.54%±0.04% vs 0.23%±0.03%), and the difference was statistically significant (t=17.54, P<0.05). The serum IL-9 level of transgene modeling group was higher than that of WT modeling group ((170.23±5.69) pg/mL vs (150.62±6.45) pg/mL), and the difference was statistically significant (t=6.50, P<0.05). The level of IL-9 secreted by LMPC of transgene modeling group was higher than that of WT modeling group ((265.21±8.76) pg/mL vs (237.58±10.24) pg/mL), and the difference was statistically significant (t=5.80, P<0.05). The expressions of IL-9 protein and mRNA of transgene modeling group were higher than those of WT modeling group (1.31±0.09 vs 1.18±0.03, and 8.26±1.13 vs 2.25±0.29, respectively), and the differences were statistically significant (t=3.88 and 14.57, both P<0.05).

TL1A high expression in lymphocytes can promote Th9 cells differentiation and IL-9 secretion which involved in the genesis of chronic experimental colitis.

Inflammatory bowel diseases; Colitis, ulcerative; Interleukin-9; TL1A; T helper 9 cells; Mice