Impact of TRAIL gene knockout on regulatory T cells in mice with dextran sodium sulphate-induced experimental colitis / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the impact of knocking out tumor necrosis factor-related ap-optosis-inducing ligand ( TRAIL) gene ( TRAIL-/-) on colonic inflammation and regulatory T cells ( Treg) in mice with dextran sulfate sodium (DSS)-induced experimental colitis. Methods C57BL/6 mice were ran-domly assigned into four groups with 10 in each groupwild-type ( WT) control, WT colitis, TRAIL-/- con-trol and TRAIL-/- colitis. The mouse model of colitis was induced by oral administration of 3. 5％ DSS and the severity of colonic inflammation was assessed. Peripheral blood mononuclear cells ( PBMCs) and mesen-teric lymph nodes ( MLNs) were collected. The ratios of Treg cells to CD4+T cells in PBMCs were detected by flow cytometry. Expression of Treg cell-associated transcription factor (Foxp3) and cytokine (IL-10) at mRNA level was measured by real-time fluorescent quantitative polymerase chain reaction. Western blot and enzyme-linked immunosorbent assay ( ELISA) were used to detect the expression of Foxp3 and IL-10 at pro-tein level, respectively. Results Compared with the WT control group, the WT colitis group showed signif-icantly decreased proportions of Treg cells in PBMCs [(1. 85±0. 38)％ vs (3. 12±0. 69)％, P<0. 05], but increased proportions in MLNs [(11. 79±1. 18)％ vs (6. 24±1. 04)％, P<0. 05]. Compared with the WT mice with colitis, the TRAIL-/- mice with colitis had more severe colonic inflammation and significantly in-creased proportions of Treg cells in PBMCs [(3. 15±0. 64)％ vs (1. 85±0. 38)％, P<0. 05], but de-creased Treg cells in MLNs [(9. 80±0. 50)％ vs (11. 79±1. 18)％, P<0. 05]. Expression of Foxp3 and IL-10 at mRNA and protein levels in PBMCs of the WT mice with colitis was significantly lower than that in the WT control mice [ Foxp3 mRNA 0. 48 ± 0. 21 vs 1. 06 ± 0. 31, IL-10 mRNA 0. 23 ± 0. 07 vs 1. 22 ± 0. 38;Foxp3 protein0. 68±0. 12 vs 1, IL-10 protein(4. 91± 0. 72) pg/ml vs (21. 86±2. 40) pg/ml;all P<0. 05], while in MLNs, the expression of Foxp3 and IL-10 at mRNA and protein levels was significantly higher than that of the WT control group [Foxp3 mRNA3. 71±0. 49 vs 1. 03±0. 15, IL-10 mRNA11. 98 ±6.10 vs 1. 01±0. 31; Foxp3 protein 1. 60±0. 03 vs 1, IL-10 protein (1260. 00±18. 02) pg/ml vs (1184. 00±38. 62) pg/ml;all P<0. 05]. Compared with the WT mice with colitis, the TRAIL-/-mice with colitis showed significantly increased expression of Foxp3 and IL-10 at mRNA and protein levels [ Foxp3 mRNA1. 80±0. 49 vs 0. 48±0. 21, IL-10 mRNA1. 67±0. 99 vs 0. 23±0. 07;Foxp3 protein1. 10±0. 01 vs 0. 68±0. 12, IL-10 protein(31. 33± 25. 02) pg/ml vs (4. 58±3. 73) pg/ml; all P<0. 05], while de-creased expression in MLNs [ Foxp3 mRNA 0. 49 ± 0. 21 vs 3. 71 ± 0. 49, IL-10 mRNA 2. 80 ± 1. 82 vs 11. 98±6. 10; Foxp3 protein 1. 21±0. 12 vs 1. 60±0. 03, IL-10 protein (1158. 00±26. 48) pg/ml vs (1190. 00±37. 19) pg/ml;all P<0. 05]. Conclusions Knocking out the expression of TRAIL might af-fect the ratios of Treg cells in peripheral blood and MLNs, thereby aggravating the colitis in mice.