Aberrant expression of miR-21 in patients with inflammatory bowel disease: A protocol for systematic review and meta analysis

BACKGROUND: microRNAs have drawn more attention due to their function on the inflammatory process. The association between microRNA-21 (miR-21) expression and risk of inflammatory bowel diseases (IBD) remain inconclusive. This study was aimed to acquire a more exact estimation of this relationship. METHODS: Relevant studies were identified through searching PubMed, Embase, Wanfang, and China National Knowledge Infrastructure database. Pooled standardized mean difference and 95% confidence intervals were calculated using a random-effect model. Publication bias test, sensitivity analysis and subgroup analysis were carried out. RESULTS: A total of 20 relevant articles comprising 540 patients with ulcerative colitis (UC), 459 patients with Crohn disease (CD) and 511 non-IBD controls were included in this analysis. The expression of miR-21 was significantly increased in colon tissue of both UC and CD patients compared with non-IBD controls. However, there were no significant differences between patients with UC and CD. Moreover, increased miR-21 expression was associated with disease activity status in UC patients, but not in CD patients. CONCLUSIONS: This meta-analysis demonstrates that the higher miR-21 expression in colon tissue is positively associated with the development of UC and CD, and miR-21 might serve as a disease marker of IBD.