The Effect Of Vitamin D Deficiency On Chronic Alcoholic Liver Injury Based On Intestinal Flora-Gut-Liver Axis

Objective Based on the intestinal flora-intestinal-hepatic axis,the effects of vitamin D deficiency on intestinal flora and intestinal barrier function and the pathogenesis of inflammation of alcoholic liver injury were discussed.Methods The 4-week-old male C57BL/6Cnc mice were randomly divided into four groups: control group(Ctrl),vitamin D deficiency group(VDD),alcohol group(Et OH)and alcohol combined vitamin D deficiency group(Et OH+VDD).The four groups were fed with the corresponding diet: the control group was fed with the normal liquid diet,the VDD group was fed with the normal liquid diet lacking vitamin D,the Et OH group was fed with the Lieber-De Carli alcohol diet,and the Et OH+VDD group was fed with the non-vitamin D alcohol diet.Weekly monitoring of weight changes and collection of mice faeces during feeding.After 6 weeks of dissection,serum was collected to detect ALT and AST levels and 25(OH)D levels.After the liver was weighed,a square part of the large lobe of the liver was fixed with 4% paraformaldehyde,and paraffin sections were prepared to evaluate the degree of liver injury.The remaining part of the liver was stored in a-80℃ refrigerator,and the expressions of various inflammatory factors were detected by real-time quantitative PCR and western blot analysis.After the colon was removed,the length was measured and stored in a-80℃ refrigerator.Real-time quantitative PCR and western blot analysis were used to detect the expression levels of various inflammatory factors and the protein expression levels of intestinal compact junction proteins.Results The serum concentrations of 25(OH)D in the control group and the alcohol group were(57.64 ± 2.1 ng/m L)and(56.18 ± 2.94 ng/m L),respectively,which were significantly higher than that in the vitamin D deficiency group(12.82 ± 1.4 ng/m L)and the alcohol combined vitamin D deficiency group(10.36 ± 2.23 ng/m L),indicating the success of vitamin D deficiency modeling.Compared with the control group,the mice in the alcohol group lost weight,but the liver weight and liver coefficient increased,the length of colon shortened,and the serum ALT and AST content increased significantly.A large number of lipid droplets and inflammatory cells were observed in the pathological sections of the liver.The m RNA levels of the pro-inflammatory factor tnf-α,il-6,il-1β and the chemokine ccl2 were significantly increased in the liver.The expression of inflammatory proteins in liver tissues was significantly increased.The m RNA levels of the pro-inflammatory cytokines tnf-α,il-6,il-1β and the chemokine ccl2 in the intestinal tissues were also significantly increased.The expression levels of Occludin and E-cadherin in intestinal tissues were significantly decreased.Compared with the alcohol group,the weight loss and liver increase of the mice in the vitamin D deficiency group were not statistically significant.But on the basis of chronic alcohol intake,lack of vitamin D increases the coefficient of mice liver and serum ALT levels,further increase the liver and intestinal inflammation related genes m RNA level,raised related protein expression level of liver inflammation,significantly reduce the intestinal barrier function of protein expression levels,to further activate the NF-κB pathway.Four groups of mice in intestinal flora analysis found that the composition of flora has significant differences,on the level of the phylum,Firmicutes and cyanobacterium has a significant difference between the four groups,on the level of the family,leuconostocaceae,mogibacteriaceae,peptostreptocoaceae,responding to prevotellaceae,xanthomonadaceae has a significant difference between the four groups.Conclusions On the basis of chronic alcohol intake,vitamin D deficiency further affected the composition of intestinal flora in mice,down-regulated the expression of intestinal barrier tight junction protein,up-regulated the expression of intestinal inflammatory cytokines and liver inflammatory cytokines,and further activated the inflammatory NF-κB pathway in liver tissues to aggravate alcoholic liver injury.