ABSTRACT
AIM:To investigate the change of intestinal flora distribution and its relationship with interleukin -23(IL-23)/IL-17 axis in ulcerative colitis(UC)patients.METHODS:The fresh fecal samples from 20 patients with ac-tive UC and 20 healthy controls were collected.The distribution of the flora was analyzed by direct smear and traditional bacterial culture.The changes of bacteria were detected by real-time PCR.The hemoglobin,albumin,erythrocyte sedimen-tation,and C-reactive protein levels were tested routinely.Both normal and damaged mucosal tissues of UC patients were examined and obtained by colonoscopy,and further assessed by Mayo scoring,Baron grading and HE staining.The expres-sion of IL-17 and IL-23 was observed by immunohistochemistry and Western blot.RESULTS:(1)The degree of flora im-balance in active UC patients was higher than that in the healthy controls(P<0.05).(2)The results of aerobic culture showed that the number of Escherichia coli in the UC patients was significantly lower than that in the normal controls(P<0.01),while Enterococcus was increased obviously(P<0.01).The results of anaerobic culture revealed that the numbers of Bacteroidetes,Bifidobacterium bifidum and Lactobacilli in the UC patients were significantly decreased(P<0.01).(3) Quantitative analysis of target bacteria showed that the relative quantification of Escherichia coli,Bacteroidetes,Bifidobacte-rium bifidum and Lactobacilli in the UC patients was significantly lower than that in the normal subjects,and the number of Enterococcus was significantly increased(P<0.01).(4)Compared with control group,no significant change of hemoglo-bin in the UC patients was ovserved,albumin was significantly decreased(P<0.05), but erythrocyte sedimentation and C-reactive protein levels were elevated obviously(P<0.01).(5)The Mayo score, Baron grade, and histopathological score were all increased(P<0.01).(6)High IL-17 and IL-23 expression levels were detected in the UC patients(P<0.01).(7)Correlation analysis showed that the average absorbance values of IL -17 and IL-23 expression were positively correlated with Baron grade(r=0.717,P=0.02;r=0.849,P=0.016)and pathological score(r=0.660, P=0.03;r=0.675,P=0.032).Meanwhile, the average absorbance value of IL-23 expression was negatively correlated with the number of Escherichia coli(r =-0.699, P =0.025), and positively correlated with Enterococcus(r =0.872, P =0.010).Furthermore,the average absorbance value of IL-17 expression was positively correlated with Enterococcus(r=0.764,P=0.046),and both of them were not correlated with other bacteria.CONCLUSION: Obvious flora imbalance exists in active UC patients,changed intestinal microflora is closely related with the degree of inflammation.IL-23/IL-17 axis,as a key factor in the development of UC,may be related to the changes of intestinal microflora.The interaction be-tween intestinal microflora and IL-23/IL-17 axis plays an important role in the pathogenesis of UC.