| Ulcerative colitis (UC), one of the two types of inflammatory boweldisease (IBD) with unclear mechanism, is believed to be caused by intestinemucosal dysimmunity, persistent gut inflammation, genetics and environment,especially the first one. CD4+T cells, containing T helper (Th) cells and Tregulatory (Treg) cells, are the key effector cells in immune system byregulating immune responses and immune balance. One of the prominentfeatures of UC is the imbalance between pro-inflammation andanti-inflammation caused by the proliferation and differentiation of CD4+Tcells.Combination of transforming growth factor-β (TGF-β) and interleukin-4(IL-4) is newly found to generate IL-9-secreting cells from na ve CD4+T cells.With the presence of TGF-β, Th2cells can also be activated to produce IL-9.Those IL-9-producing cells were named Th9cells due to the uniquedifferentiation pathway. Th9cells have been well studied in autoimmunecerebrospinal meningitis, tuberculous pleurisy and atopicdermatitis. Additionally, murine colitis has been well established bytransferring Th9cells into recombination-activating gene1-deficient(RAG-1) mice.The tumor necrosis factor-like ligand1aberrance (TL1A) is a proteinmember of the tumor necrosis factor superfamily15(TNFSF15), mainlyexpressed in human endothelial cells, including human umbilical veinendothelial cells, adult skin microvascular endothelial cells and myometriumendothelial cells. TL1A was also found to be a susceptibility gene for IBD andplay a pro-inflammatory role in human intestinal inflammation. TL1A caninduce intestine mucosal dysimmunity by stimulating Th1, Th2and Th17cellsto contribute to tissue inflammation by combination with death receptor 3(DR3). However, the effect of TL1A on Th9cells is unclear. This study wasdesigned to investigate the role of TL1A on activation of Th9cells usingTL1A transgenic (Tg) mice and wide type (WT) mice.Objective: To investigate the essential function of TL1A on activation ofTh9cells in murine chronic experimental colitis model.Methods:(1)Tg mice with lymphocytes over-expressing TL1A andC57BL/6wide type(WT) mice were used in this study.(2)A total of12WTmice with the same genetic background (15-18g，6-8weeks) were randomlyassigned to the Control/WT group (n=6) and DSS/WT group (n=6); a total of12Tg mice (15-18g,6-8weeks) were randomly assigned to the Control/Tggroup (n=6) and DSS/Tg group (n=6). The Control/WT group and Control/Tggroup were administrated by distilled water; the DSS/WT and DSS/Tg groupreceived3%DSS drinking water on day1-5,8-12,15-19,22-26,27and28,distilled water was given during the remaining time. The mice were harvestedon day29.(3)Severity of colitis was evaluated by body weight (BW) changes,stool consistency, stool blood and the disease activity index (DAI).(4)Thechanges of colon morphology and colon length were measured in each groupto get the gross score.(5)Hematoxylin and eosin (H&E) staining was used toget The histopathology changes and pathology score of colitis weredetermined by.(6)MPO was measured in each group.(7)The lamina propriamononuclear cells (LPMC) were isolated and counted, and the percentage ofTh9cells (CD4+IL9+T) in CD4+T cells was measured by flow cytometry.Results:(1)BW changes: The BW increased in both Control/WT group(42.06%±6.41%) and Control/Tg group (35.26%±2.70%). DSS/WT groupmice got significant lower BW increase than Control/WT group(9.28%±5.70%vs42.06%±6.41%, P<0.05). The BW of DSS/Tg group wasdecreased significantly compared to Control/Tg group (-9.66%±2.50%vs35.26%±2.70%, P<0.05) and DSS/WT group (-9.66%±2.50%vs9.28%±5.70%, P<0.05).(2)DAI: The DAI score was0.00±0.00in both control groups.The DAI score was significantly increased in DSS/Tg group comparing toDSS/WT group (2.55±0.90vs1.58±0.70, P<0.05).(3)No morphological changes were found in the colon tissues of the Control/WT group andControl/Tg group. Compared to Control/WT group, the colon length ofDSS/WT group decreased significantly (6.38±0.47vs7.63±0.54, P<0.05), andthe gross score (1.60±0.31) and histopathology score (9.50±0.79) wereincreased significantly based on mucosal epithelial defects, inflammatory cellinfiltration and shallow ulcers generation comparing to control groups(0.00±0.00, P<0.05). Colon length of DSS/Tg group decreased significantlycompared with DSS/WT (5.30±0.18vs6.38±0.47, P<0.05), and themorphology score (2.80±0.64vs1.60±0.31, P<0.05) and histopathology score(11.85±0.86vs9.50±0.79, P<0.05) were significantly higher than DSS/WTgroups.(4)The MPO of DSS/WT group were significant higher than that ofthe Control/WT group (1.48±0.40vs0.65±0.26, P<0.05), and Tg/DSS groupincreased significantly compared with Control/Tg group (2.20±0.45vs0.93±0.25, P<0.05). The MPO activity of DSS/Tg group was higher thanDSS/WT group(2.20±0.45vs1.48±0.40, P>0.05), there was no statisticalsignificance between them.(5)LPMC were isolated and counted first, the totalnumber of LPMC in DSS/WT group was significantly higher than Control/WTgroup (2.65×106±0.32×106vs1.68×106±0.15×106, P<0.05); the total LPMCharvested from DSS/Tg groups were significantly higher than Control/Tggroup (3.70×106±0.28×106vs1.72×106±0.17×106, P<0.05) and DSS/WTgroup (3.70×106±0.28×106vs2.65×106±0.32×106, P<0.05). Flow cytometry:the percentage of Th9(CD4+IL9+T) cells in total CD4+T cells was0.10%±0.02%in Control/WT group, and0.12%±0.01%in Control/Tg group.The DSS/WT group was significantly higher than Control/WT group(0.23%±0.03%vs0.10%±0.02%, P<0.05), and the DSS/Tg group wassignificantly higher than Control/Tg group (0.54%±0.04%vs0.12%±0.01%,P<0.05) and DSS/WT group (0.54%±0.04%vs0.23%±0.03%, P<0.05).Conclusion: TL1A could aggravate the intestinal mucosa inflammation,probably through regulation of Th9cell activation. |
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