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.
ABSTRACT
The present study is designed to explore the role of plasma cells in the change of protein C system (PCS) in ulcerative colitis (UC). Dextran sulfate sodium (DSS, 4% in concentration) was used to induce mouse UC model. The plasma cells and the type of immune complex in colon were observed by immunofluorescence. The amount and type of plasma cells separated from colonic mucosal lamina propria were detected by flow cytometry using anti-CD54CD38and IgA/M/G antibodies, respectively. After stimulation of macrophages by IgG type immune complex, TNF-α and IL-6 levels were evaluated by ELISA. After co-incubation of microvascular endothelial cells with TNF-α or IL-6, the expressions of endothelial protein C receptor (EPCR) and thrombomodulin (TM), and the activity of activated protein C (APC) were examined. As the results showed, the IgG type plasma cells infiltration and the quantity of IgG type immune complex were increased in DSS group in comparison with control group. After incubation with IgG type immune complex, the levels of TNF-α and IL-6 in the supernatant of macrophages were increased (P < 0.01) in a concentration-dependent manner. Meanwhile, after incubation with TNF-α or IL-6, the expressions of EPCR and TM in the microvascular endothelial cells were decreased (P < 0.05 or P < 0.01), while the activity of APC was reduced (P < 0.05 or P < 0.01). These results suggested that the quantity of IgG type plasma cells increases in UC and forms immune complexes, which affect the secretion of cytokines from macrophage, thereby affecting the function of endothelial cells and finally inhibiting PCS in UC. Therefore, plasma cell may be a novel target for the treatment of UC.