Study on the Effect and Mechanism of Bletillae Rhizoma on Repairing Intestinal Mucosal Barrier in Rats with Ulcerative Colitis by Regulating Neutrophil Extracellular Traps
Objective To investigate the repair effect of Bletillae Rhizoma on intestinal mucosal barrier in rats with ulcerative colitis(UC)based on neutrophil extracellular traps(NETs).Methods Forty-eight SD rats were randomly divided into normal group,model group,Sulfasalazine group(0.3 g·kg-1),Bletillae Rhizoma low-,medium-and high-dose groups(0.3,0.6,1.2 g·kg-1),with 8 rats in each group.The UC rat model was established by 2,4,6-trinitrobenzene sulfonic acid(TNBS)-ethanol enema.After successful modeling,the corresponding drugs were given by gavage for 21 days.The normal group and the model group were given equal volume of normal saline by gavage.The disease activity index(DAI)was evaluated on the first,eleventh and twenty-first day of administration.Hematoxylin-eosin(HE)staining was used to observe the colon pathology of rats in each group.The levels of tumor necrosis factor-α(TNF-α)and interleukin-1β(IL-1β)in serum were measured by enzyme-linked immunosorbent assay(ELISA).Immunohistochemistry(IHC)and Western Blot(WB)were used to detect the expressions of NETs-related proteins myeloperoxidase(MPO),neutrophil elastase(NE),vascular endothelial growth factor(VEGF),tight junction(TJs)-related proteins claudin-2(CLDN2)and zonula occludens-1(ZO-1)in colon tissue.Results Compared with the normal group,the DAI of rats in the model group was significantly up-regulated(P＜0.05),and the pathological conditions such as mucosal necrosis and inflammatory infiltration appeared in the colon tissue.The contents of TNF-α and IL-1β in serum were significantly increased(P＜0.05),and the protein expressions of MPO,NE,VEGF and CLDN2 in colon tissue were significantly increased(P＜0.05),and the protein expression of ZO-1 was significantly decreased(P＜0.05).Compared with the model group,the DAI of rats in each administration group was significantly decreased(P＜0.05).The colonic intestinal gland structure of rats in the Sulfasalazine group and the medium-and high-dose groups of Bletillae Rhizoma was complete and clear,there was no obvious degeneration and necrosis of the mucosa,a small amount of inflammatory cell infiltration was observed,and the pathological score was significantly decreased(P＜0.05).The levels of serum TNF-α and IL-1β were significantly decreased(P＜0.05).The protein expressions of MPO,NE,VEGF and CLDN2 in the colon were significantly decreased(P＜0.05),and the expression of ZO-1 was significantly increased(P＜0.05).Conclusion Bletillae Rhizoma may regulate the expression of TJs-related proteins by regulating the production of NETs,thereby improving the intestinal mucosal barrier injury and inflammatory infiltration in rats to play a therapeutic role in UC rats.
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