The Effect And Significance Of Vitamin D On Gut Microbiota In Mice With Ulcerative Colitis

Objective:To investigate the effect of different doses of vitamin D on Ulcerative colitis?UC?mice,by immunohistochemical detection of?-defensin-2 in the expression of the colon and RT-QPCR detection method of intestinal flora in mice,observed the number of intestinal flora in mice UC superiority strains and the change of the structure,to observe the effects of different concentrations of vitamin D on UC,provide evidences for the further research.Method:35 healthy mice aged 6-8 weeks,with body weight of 20-22g,were divided into:?1?Con group?2?Model con group?3?Mesalazine group?4?VitD-H group?5?VitD-H group.28 mice were given free drinking 2.5%dextran sulfate?DSS?for 7 days to establish acute UC mouse model,and 7 distilled water was given free drinking in Con group.After successful modeling in UC mice,drug intervention was given:50ng/kg VitD₃ gavage in VitD-L group;VitD-H:500ng/kg VitD3 gavage;Mesalazine group:Mesalazine?110mg/kg?was given by gavage.Model con group,Con group:same amount of peanut oil gavage.After7 days of intervention,mice were sacrificed and colon tissues were collected.Colon tissue of the lesion site was taken for hematoxylineosin staining,observed under microscope,and histopathological score was obtained.Immunohistochemical staining was performed to observe the expression of?-defensin-2 in colon lesions.Mouse feces were collected and genomic DNA of fecal flora was extracted.RT-QPCR technology was used to quantitatively detect the content and structure changes of bacteroides,bifidobacterium,E.coli and enterococcus in feces.Results:1.DAI score and histological score:DAI score decreased gradually after successful modeling.After 7 days of intervention,DAI changes of different intervention methods were observed.DAI scores of the Model con group were significantly different from those of the VitD group?P<0.05?;there was no significant difference between the VitD-H group and the mesalazine group?P>0.05?;there was significant difference between the VitD-H group and the VitD-L group?P<0.05?.Pathological damage in VitD group was reduced to different degrees compared with that in Model con group.The pathological score of VitD intervention group was significantly lower than that of Model con group?P<0.05?.There were also differences in pathological scores between VitD-H and VitD-L groups?P<0.05?.2.Expression of?-defensin-2:the expression of?-defensin-2 was weak in Con group,VitD group and mesalazine group,but strong in Model Con group.Compared with the Model con group,there were statistically significant differences in the expression of ?-defensin-2 after VitD intervention with different concentrations?P<0.05?.Compared with Con group and mesalamine group,there was no statistically significant difference in the expression of?-defensin-2 in VitD-H group?P>0.05?,while there were statistically significant differences in the expression of beta-defence-2 in VitD-L group and VitD-H group?P<0.05?.?-defensin-2 expression was positively correlated with histopathological grading?r=0.608,P<0.05?3.The change of intestinal flora:?1?Bacteroidetes:the content of bacteroidetes in VitD-H group was higher than that in Mesalazine group,VitD-L group and Model con group,while that in VitD-L group was lower than that in mesalazine group,VitD-H group and Con group,and that in Mesalazine group was lower than that in Con group and VitD-H group,and higher than that in VitD-L group and Model con group,with statistically significant differences?P<0.05?.?2?Bifidobacteria:there were significant differences between VitD-H group and VitD-L group,Mesalazine group,and Model con group?P<0.05?,and significant statistical significance was found between VitD-L group and Con group,Model con group,and VitD-H group?P<0.05?.?3?E.coli:the content of e.coli in VitD-H group was lower than that in Model con group and VitD-L group.The content of VitD-L group was relatively increased,showing little difference compared with Model con group?P>0.05?,but higher than Con group,Mesalazine group and VitD-H group,showing statistical significance ?P<0.05?.?4?Enterococcus:the enterococcus content of VitD-H group with Mesalazine is higher than that in Con group,lower than the Model Con,VitD-L group,the difference had statistical significance?P<0.05?,enterococcus VitD-L group belongs to the content is relatively higher,with the Model Con group no significant difference?P>0.05?,higher than the VitD-H group,Mesalazine,the difference is statistically significant?P<0.05?.4.The composition of intestinal flora in normal mice was dominated by the dominant bacteria bacteroides and bifidobacteria,while the content of conditional pathogenic bacteria escherichia coli and enterococci was relatively small.The composition of intestinal flora in the VitD-H group was dominated by dominant bacteria,showing no statistical difference compared with Con group?P>0.05?,and little difference compared with Mesalazine group?P>0.05?.The content of dominant bacteria in the intestinal tract of Vit-Lgroup was slightly higher than that of conditioned pathogens,and the structural composition was significantly different from that of VitD-H group and Con group?P<0.05?.5.Correlation between intestinal species and expression of?-defensin-2:the expression of intestinal?-defensin-2 was negatively correlated with bacteroides and bifidobacteria?r=-0.543,r=-0.662?,and positively correlated with e.coli and enterococcus?r=0.497,r=0.564?.Conclusion:VitD interferes with acute UC mice,affects the expression of?-defensin-2,changes the content and structure of intestinal flora through the expression of?-defensin-2,and improves the maintenance of intestinal microenvironment and intestinal gut Inflammation of the tract,and there is a dose-effect relationship.The application of VitD in the acute phase of UC can alleviate the acute phase symptoms of UC,improve intestinal mucosal damage,and is superior to mesalazine in regulating intestinal flora.