Expression And Role Of IL-22 And IL-22BP In Intestinal Mucosa Of Patients With Active Inflammatory Bowel Disease

Objective: Studies have shown that interleukin-22(IL-22)has the protective effect on the intestinal tract.Interleukin-22 binding protein(IL-22BP)is the natural and specific inhibitor of IL-22 and can inhibit the function of IL-22.Expression and role of IL-22 and IL-22 BP in intestinal mucosa of patients with active inflammatory bowel disease(IBD)remains unclear.Through investigating the expression of IL-22 and IL-22 BP in intestinal mucosa of patients with active IBD,we intend to explore their clinical significance.Methods: The active IBD patients diagnosed and treated at Shanghai General Hospital,Shanghai Jiaotong University from March 2016 to February 2018 were enrolled.The disease activity of ulcerative colitis(UC)and Crohn's disease(CD)was assessed by Mayo score and simplified CD activity index(CDAI)respectively.The inflamed intestinal mucosal tissues were obtained.Patients with colonic polyp were served as controls and normal intestinal mucosal tissues were obtained.According to the location the samples taken from,we divided them into control group of UC and control group of CD.The former includes normal colonic tissues of different patients,the latter includes normal colonic or ileal tissues of different patients.Expressions of IL-22 and IL-22 BP m RNA and protein in intestinal mucosa were determined by real-time PCR and immunohistochemistry respectively.The result of immunohistochemistry was analyzed by semi-quantitative integration.We used the Spearman's rank correlation coefficient to do the correlation analysis.Results: A total of 68 patients with active IBD were enrolled,including 38 UC and30 CD.Thirty patients with colonic polyp were served as controls.Compared with corresponding control group,expressions of IL-22 and IL-22 BP m RNA in intestinal mucosa of UC and CD group were significantly increased(P<0.05).Expression of IL-22 protein in intestinal mucosa of UC group,CD group,control group of UC and control group of CD was(6.00±2.28),(6.43±2.43),(0.90±1.3)and(1.47±2.01)respectively.Expression of IL-22 BP protein in intestinal mucosa of UC group,CD group,control group of UC and control group of CD was(5.53±2.23),(5.97±2.16),(1.83±1.86)and(2.23±1.77)respectively.Expressions of IL-22 and IL-22 BP protein in intestinal mucosa were also significantly increased in UC and CD than that in controls(P<0.05).Expression of IL-22 BP protein in intestinal mucosa was positively correlated with disease activity of UC(r=0.749,P<0.05)and CD(r=0.707,P<0.05).The ratio of IL-22 and IL-22 BP protein(IL-22/IL-22BP)in intestinal mucosa was negatively correlated with disease activity of UC(r=-0.725,P<0.05)and CD(r=-0.664,P<0.05).Conclusions: Expressions of IL-22 and IL-22 BP m RNA and protein are increased in intestinal mucosa of patients with active IBD and the expression of IL-22 BP protein and the ratio of IL-22 and IL-22 BP protein(IL-22/IL-22BP)in intestinal mucosa is correlated with disease activity of IBD,which indicate that they may be involved in the pathogenesis of IBD and may have potential value in assessing the patient's condition.