| BackgroundUlcerative colitis (UC) is chronic, idiopathic, inflammatory disease with unknown etiology, which is characterized by damage of the large bowel mucosa and submucosa. The typical clinical manifestations of UC are abdominal pain, diarrhea and mucus purulent bloody stool. UC often appears insidious onset and chronic process and its disease course ranges from years to decades, besides, frequent flare-up alternating with clinical remission is detected. The incidence of UC has been increasing in recent years, however, the pathogenesis still has not been completely described. It is widely accepted that the pathogenesis of ulcerative colitis is mainly caused by the interaction of multiple factors, including the environment, gene, infection, immunity etc. Nowadays, immunologic abnormalities are often regarded as a crucial factor in the pathogenesis of ulcerative colitis, and has been the research hotspot for more and more scientists. It mainly covers the autoantibody, cytokines, cell immunity, cyclooxygenase, matrix metalloproteinases, nitric oxide and oxygen free radical. Among them, the cytokines is emphasized currently, as the imbalance between pro-inflammatory cytokines and anti-inflammatory cytokines is more considered to be a critical mechanism in the occurrence and development of ulcerative colitis and has caused widespread concern. As the most important pro-inflammatory cytokines of the IL-23/IL-17 axis, IL-23 (interleukin-23) and IL-17(interleukin-17) has become a focus in the research in recent years. Previous literatures reported that IL-23 and IL-17 may be the key pro-inflammatory medium that causes intestinal inflammation, and play a key role in the development and incidence of ulcerative colitis. Although a number of studies have revealed the increased expression of IL-23 and IL-17 in the intestinal mucosa of ulcerative colitis and plasma, the correlation between their expression and intestinal mucosal healing of the ulcerative colitis patients after short-term treatment is rarely reports.Previous study of ulcerative colitis mainly focused on pro-inflammatory cytokines, but in recent years, researchers have paid more attention to the anti-inflammatory cytokines which is also approved to play a role in ulcerative colitis.Both interleukin-22 and interleukin-11, have been shown to participate in a variety of inflammatory diseases and the development process of autoimmune disease. Besides, it has been demonstrated that the expression of IL-22 in Intestinal mucosa of patients with IBD enhanced. So it is in evidence that IL-22 is associated with ulcerative colitis disease process. However, whether it play a role as an aggressive mediator in inflammatory lesion or a protective factor against the inflammatory damage, it is still controversial. It was once considered that IL-22 is a pathogenic factor due to its correction with the expression of other pro-inflammatory factor, but recent studies gradually show that it mainly makes a protective effect against the intestinal mucosa injury. From several preclinical data of the IBD model, it has been described that IL-22 plays a protective role by strengthening the integrity of the intestinal epithelial barrier and innate immunity. IL-11, is well known as a pleiotropic cytokine. Previously, research mainly focused on its role in the secondary thrombocytopenia. However, discovered in recent years, IL-11 shows anti-inflammatory effects in a number of in vivo animal model, such as enteritis, dermatitis, endotoxin sepsis and autoimmune arthritis. Domestic and foreign scholars also conducted a series of experimental study for its application in the repair of the intestinal damage, such as intestinal injury caused by radiotherapy and chemotherapy, short bowel syndrome and inflammatory bowel disease, etc. And the results showed that IL-11 played a good role on bowel protection and the promotion to the repair of intestinal injury. But at present, the distribution and expression of IL-22 and IL-11 in ulcerative colitis intestinal mucosal tissue, and its relationship with the ulcerative colitis disease activity, the endoscopic activity grading, the intestinal mucosal histopathological grade and the intestinal mucosal healing after short-term treatment of UC are not clarified.Therefore, in this research we examine the distribution and expression levels of the cytokine IL-23, IL-17, IL-22 and IL-11 in the mucosal biopsies obtained from patients with ulcerative colitis and the healthy control by immunohistochemistry method, and then analyze the relationship between its expressions and the ulcerative colitis disease activity, the endoscopic activity grading, and the intestinal mucosal histopathological grade. Besides, we also analyzes the correlation between these cytokine. At last, we combine the immunohistochemistry results with the follow-up information of patients with active UC and further analyzes the association between the expressions of such cytokines and the intestinal mucosal healing after short-term treatment of UC.We aim at exploring the function and relationship of these cytokines in the pathogenesis of ulcerative colitis, and hope to provide valuable reference for the ulcerative colitis clinical diagnosis and its evaluation of prognosis.Content1. Detect the expression and distribution of IL-17, IL-23, IL-22 and IL-11 in intestinal mucosa of patients with ulcerative colitis, and analyzes their relationship with the disease activity, the ulcerative colitis endoscopic activity grade, and histopathologic grade, and further analyze the relationship between the expressions of each cytokine in intestinal mucosa.2. Combining the immunohistochemistry results with the follow-up information of patients with active UC, and then analyze the correlation of IL-17, IL-23, IL-22, IL-11 with prognosis of mucosal healing.Objects and methods1. Two step immunohistochemical staining was conducted to detect distribution and expression of IL-17,IL-23, IL-22, IL-11 in the intestinal mucosa among 40 case of active UC patients、15 case of remittent UC patients and 15 cases of healthy control. And then compare the expression difference among these three groups. Further analyzes their relationship with the disease activity, the ulcerative colitis endoscopic activity grade, and histopathologic grade, and further analyzes the relationship between the expressions of each cytokine in intestinal mucosa.2. Immunohistochemistry method was carried to test the expression of IL-17, IL-23, IL-22, IL-11 in the intestinal mucosa of another 40 cases of patients with active UC. By combining the immunohistochemistry result with the follow-up data, we further analyze the predictive value of such cytokines in the prognosis of mucosal healing after short-term treatment.3. Statistical analysis:All data was analyzed by SPSS 20 Windows statistical software and measurement data were expressed as mean ± SD. The single factor analysis of variance (one way ANO-VA) was used to compare the expression of different group (n>3) and Bonferroni was further used to make multiple comparison between these groups with statistically significant difference after the event; Spearman correlation analysis was applied to analyze the correlation between the expression level of IL-17, IL-22, IL-23,IL-lland UC endoscopic activity grade, or histopathological grade respectively; Using Pearson correlation analysis to test the relationship between the expression of each inflammatory index. Using chi-square to compare expression level between the mucosa healing well and poor mucosal healing group, P<0.05 was considered with statistical significance.Results1.IL-17, IL-23, IL-22, IL-11 express mainly on the mucosa epithelium and mononuclear cells in the intrinsic layer, of which the cytoplasmic was stained in tan. In addition, strong positive staining in puce color was apparently observed in the intrinsic layer of the active UC intestinal mucosa after IL-17 immunohistochemical staining. And such strong positive staining was also detected in the mucosa epithelium of the active UC intestinal mucosa with IL-22immunohistochemical staining.The expressions of IL-17, IL-23, IL-22 and IL-11 between the active UC group, remittent UC group and the healthy control group all significantly different. The average optical density of IL-17, IL-23, IL-22 and IL-11 in activity UC group was significantly higher than in the remittent UC group and the healthy controls. (0.0727±0.0236 vs 0.03542±0.09416 vs 0.0330±0.0176; 0.1407±0.0433 vs 0.0865±0.0197 vs 0.0442±0.0532; 0.0522±0.0289 vs 0.0259±0.0243 vs 0.0115±0.0236; 0.0480±0.0137 vs 0.0365±0.0093 vs 0.0232±0.0038,respectively) P<0.05。Among them, the mean optical density of IL-23in the remittent UC group is also significantly higher than the healthy control group, and the difference was statistically significant (P<0.05).2. The average optical density of IL-17, IL-23, IL-22 shows significant difference between 3 groups with different disease activity from mild to severe. And the expression level significantly increase with the increase of disease activity (0.0545 ± 0.0248 vs 0.0786 ± 0.0221 vs 0.0847 ± 0.0591; 0.1112 ± 0.0158 vs 0.1480 ± 0.0392 vs 0.1644 ± 0.0572 vs 0.0307 ± 0.0218 vs 0.0548 ± 0.0311 vs 0.0719 ± 0.0169)(P< 0.05). Although the average optical density of the severe group of active UC is higher than the medium group, the difference has no statistical significant (P> 0.05). The average optical density of IL±11 in these3 groups(mild, medium and severe) also increased with the increase of disease activity (0.0446 ± 0.0147 vs 0.0483± 0.0157 vs 0.0519±0.0055), but there was no statistically significant difference between them (P> 0.05). In addition, the expression level of IL-17, IL 23, IL-22 and IL-11 in the intestinal mucosa of patients with active UC is positively correlated with the endoscopic activity grade (P<0.05).And the expression level of IL-17, IL-22 in the intestinal mucosa of patients with active UC, is also positively correlated with the histologic grade (P<0.05).3. Bivariate correlation analysis showed that the average optical density of IL-17、IL-23, IL-22, IL-11 was all positively correlated with each other.4. IL-17 expression level distribution was statistically different in the intestinal mucosa between good and poor mucosal healing group. (P<0.05).Poor mucosal healing rate was 66.67% in the IL-17 high expression group, while 25% in low expression group. Compared to the IL-17 low expression group, the rate of poor mucosal healing increased significantly in the IL-17 high expression group. (P<0.05) However, such significant difference was not found in IL-23, IL-22, IL-11(P> 0.05).Conclusion1. The expression of IL-17, IL-22, IL-23, IL-11 in active UC group were significantly higher than those in normal controls and remittent UC group. And the expression level is correlation with the severity of patients with active UC, so maybe it can be used to evaluate the severity of UC in patients.2. Compared to the IL-17 low expression group, the rate of poor mucosal healing increased significantly in the IL-17 high expression group, so it may be able to evaluate the prognosis of mucosal healing.3. From this research we gain a preliminary understanding of IL-17, IL-22, IL-23, IL-11 expression and its clinical significance in ulcerative colitis patients, Besides, it is more clear that these cytokines all play a certain role in the pathogenesis of ulcerative colitis, and may be able to evaluate the inflammatory activity or assess the prognosis of mucosal healing. In addition, we hope that it could provide the theory basis for the further in-depth and comprehensive study. At the same time, we expect that new therapeutic targets and a more reasonable treatment strategy can be developed in a certain day by the use of molecular target blocking inflammatory, regulating immune pathway and so on. |
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