JIN Yingli,XIA Xuanping,CAO Shuguang, et al. Effect of TRAIL-R deficiency on apoptosis of Th17 cells in experimental colitis mice induced by dextran sodium sulfate[J]. JOURNAL OF WEZHOU MEDICAL UNIVERSITY, 2020, 50(12): 947-955.
Abstract：Objective: To investigate the effect of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene knockout (TRAIL-R-/-) on the severity of colitis and the apoptosis of Th17 cells in mice induced by 3.5% dextran sodium sulfate (DSS). Methods: C57BL/6 mice were assigned into 4 groups: TRAILR-/-colitis group, TRAIL-R-/- control group, wild type (WT) colitis group and WT control group, with 9 mice in each group. Colitis groups were orally administrated by 3.5% DSS. Control groups were fed with the same volume of water. After 7 days, the severity of colitis in mice was evaluated clinically and histopathologically.In peripheral blood mononuclear cells (PBMCs) and colonic lamina propria mononuclear cells (LPMCs), the proportion of Th17 cells in CD4+ T cells was detected by means of flow cytometry. The mRNA and protein expressions of retinoic acid-related orphan receptor-γt (ROR-γt) and IL-17A were measured using real-time quantitative polymerase chain reaction (RT-qPCR), western blot and enzyme linked immunosorbent assay (ELISA). The apoptosis rate of Th17 cells in colonic tissue was examined by TUNEL fluorescence staining technique and observed by laser confocal microscope. The activity of Caspase 3, Caspase 8, Caspase 9 in colonic tissue was assayed by colorimetric method. Results: After administration of 3.5% DSS, TRAIL-R-/- colitis mice exhibited more severe colitis than WT colitis group did. The proportion of Th17 cells in PBMCs of TRAIL-R-/- colitis group was shown to be significantly higher in TRAIL-R-/- colitis group than in WT colitis group (P<0.01).The same conclusions were also drawn for the mRNA and protein levels of ROR-γt and IL-17A in PBMCs when compared WT colitis group with TRAIL-R-/- colitis group (both P<0.05). In comparison with WT colitis group, the proportion of Th17 cells in colonic LPMCs of TRAIL-R-/- colitis group was significantly enhanced in TRAILR-/-colitis group (P<0.01). The mRNA and protein levels of ROR-γt and IL-17A were also found to be higher in TRAIL-R-/- colitis group than in WT colitis group (both P<0.05). In contrast to WT colitis group, the apoptosis rate of Th17 cells in colonic tissue of TRAIL-R-/- colitis group was significantly reduced in TRAIL-R-/- colitis group (P<0.01). Meanwhile, the activities of Caspase 3 and Caspase 8 were shown to be significantly lower in TRAIL-R-/- colitis group than in WT colitis group (both P<0.01). Conclusion: After administration with DSS,TRAIL-R-/- colitis mice manifested more severe colitis than WT colitis group did, which may result from the decrease in apoptosis of Th17 cells and the increase in number and activity of Th17 cells.
