Expression Of Interleukin-17 And Interleukin-23 In Intestinal Mucosa Of Patients With Inflammatory Bowel Disease

OBJECTIVESInfammatory bowel disease(IBD) includes ulcerative colitis(UC) and Crohn's disease(CD).The etiology and pathogenesy are not clear so far.The treatments are lack of specificity,and the disease can't be cured.It's generally accepted that abnormity of immune system is very important in the development of IBD,and interleukin(IL) is the mainly lymphokine that has biological activity.This study investigates the expession of IL-17 and IL-23 in intestinal mucosa of patients with IBD,to detect the ralationship between the expession of IL-17and IL-23 and the development of IBD.MATERTIALS AND METHODSSpecimens selectionsSpecimens of 8 Crohn disease and 20 ulcerative colitis patiant and 20 controls were studied by immunohistochemical staining.The clinical diagnosis of inflammatory bowel disease were confirmed by the radiologic,endoscopic,and histologic criteria.All controls had normal colonoscopy,and the nucosal biopsies histologically normal.Main Agents1.monoclonal antibody of IL-17,IL-23 from rabbits2.diaminobenzidine,DAB 3.streptavidin(SP) marked by peroxidaseExperimental MethodsImmunohistochemistry:use of streptomycin avidin - peroxidase conjugate(S-P) method.Result determinationIL-17,IL-23 staining of the cytoplasm stained.Tissue sections shown in the cytoplasm was stained light yellow to yellow-brown are positive for cell markers, positive cells according to their number and the color intensity is divided into three: weak positive expression(+),the number of positive cells＜10%,light yellow color intensity of individual cells,or only yellow to brown-yellow staining;strong positive expression(+++),the number of positive cells＞60%,most cells were stained yellow to brown-yellow;moderately positive expression(++),the number of positive cells and the intensity of the color range between weak positive and strong positive.Every colored intensity and the background not obvious difference are negative.Intestinal mucosa lamina propria IL-17,IL-23 expression in order to count 1000 times more high-powered microscope,on average,five horizons percentage of positive cells.The above result independently judges by two person of double blind method,takes its mean value.StatisticsAll analyses were carried out by Rank test and t test with SPSS10.0 statistical software,and statistical significance was set at p＜0.01.RESULTSImmunohistochemical staining analysis localized the expression of IL-17 and IL-23 to intestinal epithelial cells and lamina propria(eosinophils,mainly).IL-17 and IL-23 staining was more intense in the intestinal epithelial cells of active ulcerative colitis compared with in that of Crohn's disease,but there was no significant difference (μ=0.426 and 0.512 separately,P>0.01 both).While there was significant difference between ulcerative colitis and controls(μ=9.691 and 12.542 separately,P<0.01 both). And there was significant differnce between Crohn's disease and controls(μ=3.251 and 3.316separately,P<0.01 both),too.Percents of IL-23 positive cells in lamina propria in Crohn's disease is higher than that in ulcerative colitis,while percents of IL-17 positive cells in Crohn's disease is lower than that in ulcerative colitis,but there was no significant difference(t=1.599 and 1.825 separately,P>0.01 both).There was dignificant difference between Crohn's disease and controls(t=5.622 and 4.387separately,P<0.01 both).And there was significant diference between ulcerative colitis and controls(t=2.891 and 8.298 separately,P<0.01 both),too.DISCUSSIONIBD is very common in the west,but the incidence inceases in our country recently.Generally,the pathogenesis of IBD is related with the abnormity of immune response of human body to enterobacteria,and abnormity of immunoregulation and signal transduction are the most common field of research.Th-17 cell is a newly discovered accessory cell subgroup of responsiveness CD4~+T cell,which has high pathogenicity.IL-17 is a promoted inflamatory cytokine, and the effector of Th-17 cell.It is very powerful at aggregating and activating neutrophilic granulocytes.In addition,IL-17 has synergistic effect with inflammatory factor TNF2αto magnificate and enhance its effect.This study shows that IL-17 expressed hingly in the intestinal mucosa of UC and CD,and less in the control in patients of active IBD.It shows that Th-17 may exist in local infiltrating lymphocytes of colon in patients of IBD.IL-23 is a cytokine closely related with IL-12,with has the same subunit p40 but connected with p35.IL-23 starts the amplication of Th-17 and mains its survival.Deficiency of IL-23 will cause the reduction of Th-17.Early functional study of IL-23 showed that IL-23 was the real etiological factor of autoimmune disease.This study shows that the expession of IL-23 is higher in intestinal mucosa of UC and CD in patients with active IBD,but is less in the intestinal mucosa of controls,which indicates that IL-23 has participated the inflammatory reaction of colon mucosa..In summary,this research indicates that the intestinal mucosa of the active IBD patients has IL-23,IL-17 higher expression than the normal group.It indicates that IL-23,IL-17 has played an important role in the progress of IBD.IL-23 induces the colon inflammation through inducing and pressing the cell Th17 to produce IL-17,IL-6 and TNF2α.The current researches indicate that IL-23/IL-17 axis may have the key point in the pathogenesis of IBD.Maybe it can become a new target for the treatment of IBD.CONCLUSIONSIL-17 and IL-23 may be involed in the pathogenesis of infammatory bowel disease.