Effect And Mechanism Of Ursodeoxycholic Acid Combined With Bifid Triple Viable On Experimental Colitis In Mice

Objective:In order to investigate the effect and mechanism of ursodeoxycholic acid,bifid triple viable and the combination drugs in the treatment of experimental colitis induced by Dextran Sulfate Sodium(DSS)in mice,we detected the expression of Toll like Receptor 4(TLR4),Nuclear Factor-κB p65(NF-κB p65)and the Farnesoid X Receptor(FXR)proteins in the epithelial tissue,so as to provide experimental basis for the treatment of Inflammatory Bowel Disease(IBD).Methods:1.Forty-eight 8-9-weeks-old female BALB/c mices were randomly divided into eight groups:control group(Control),dss group(DSS),ursodeoxycholic acid groups(30mg/kg/d,UDCA1 and 60mg/kg/d,UDCA2),bifid triple viable group(2.0?10~7CFU/ml,Bifid),the combination groups(Bifid+UDCA1 and Bifid+UDCA2)and the positive drug control group,sulfasalazine group(200mg/kg/d,Sulfa);2.Except the control group,other groups were given 3.5%DSS solution for 7 days to establish the acute colitis model.The corresponding drugs were given to different groups,the percentage of body weight decreased,fecal properties,fecal occult blood or fecal blood were observed and recorded every day to evaluate the disease activity index(DAI);the colon length was measured after administration;HE staining was used to evaluate the histological changes of each experimental group.Western Blot was used to detect the expression of IL-17A and IL-10 proteins in colonic tissues and to evaluate the level of colitis;similarly,western blot was used to detect the expression of TLR4 and NF-κB p65 proteins in colon tissue to evaluate the intestinal barrier function and imbalance of intestinal microflora;as well as to detect the expression of FXR protein in colon tissue to evaluate the metabolism of bile acids.Results:1.DAI,colon length,histopathology scores of experimental colitis mice in each group:Compared with the Control group,DSS group showed that the weight of mice decreased,mucopurulent stools appeared,DAI increased,colon length shortened,colon histology showed mucosal epithelial damaged,inflammatory cell infiltration,crypt inflammation,crypt structure destruction,and histopathology score increased significantly(P<0.05);Compared with the DSS group,there was no significant difference in UDCA1 group;UDCA2 group,Bifid group,the combination groups(Bifid+UDCA1 and Bifid+UDCA2)and Sulfa group alleviated the above pathological changes significantly(P<0.05),the combination groups had better curative effect than the corresponding single UDCA group and Bifid group(P<0.05);Compared with Bifid+UDCA2 group and the Sulfa group;There was no significant difference in the improvement effect on the increase of DAI and the reduction of colon length.2.The expression of IL-17A and IL-10 in colon of experimental colitis mice in each group:Compared with the Control group,DSS group showed that the expression of pro-inflammatory factor IL-17A protein increased(P<0.05),and the expression of anti-inflammatory factor IL-10 protein decreased(P<0.05);Compared with the DSS group,there was no significant difference in UDCA1 group,the expression of IL-17A protein decreased(P<0.05),and the expression of IL-10 protein increased in UDCA2group,Bifid group,the combination groups(Bifid+UDCA1 and Bifid+UDCA2)and Sulfa group(P<0.05),moreover the combination groups had more significant effect on the decrease of IL-17A and on the increase of IL-10 than the corresponding single UDCA group and Bifid group(P<0.05);There was no significant difference between the Bifid+UDCA2 group and the Sulfa group.It prompted that the combination drugs had better effect on fighting inflammation than single drugs.3.The expression of TLR4,NF-κB p65,FXR in colon of experimental colitis mice in each group:Compared with the Control group,DSS group showed that the expression of pathogen-related molecule pattern recognition receptor TLR4 and cascade induced NF-κB p65 were up-regulated(P<0.05),the expression of bile acid receptor FXR protein was down-regulated(P<0.05);Compared with the DSS group,there was no significant difference in UDCA1 group;UDCA2 group,Bifid group,the combination groups(Bifid+UDCA1 and Bifid+UDCA2)and Sulfa group decreased the TLR4 and NF-κB p65 protein expression significantly(P<0.05),increased the FXR expression significantly(P<0.05);The combination groups had better effect than the corresponding single UDCA group and Bifid group on inhibiting the expression of TLR4 and NF-κB p65 protein(P<0.05),improving the expression of FXR protein(P<0.05);There was no significant difference in the reduction of TLR4 and NF-κB p65 protein expression between the Bifid+UDCA2 group and the Sulfa group.The results showed that the combination drugs could improve intestinal mucosal barrier function,intestinal flora imbalance and intestinal bile acid metabolism.Conclusions:1.High doses of ursodeoxycholic acid,bifid triple viable and the combined therapy can reduce DAI,colon length and histopathological injury;2.High doses of ursodeoxycholic acid,bifid triple viable and the combined therapy can regulate abnormal inflammatory responses by down-regulating colonic inflammatory factor IL-17A and up-regulating the expression of anti-inflammatory factor IL-10;3.High doses of ursodeoxycholic acid,bifid triple viable and the combined therapy could inhibit the expression of TLR4 and NF-κB p65,increase the expression of FXR,and regulate the function of intestinal mucosal barrier,intestinal flora balance and bile acid metabolism;4.The combination of drugs has better efficacy than single drug,and has better therapeutic effect on experimental colitis mice.