Mucin gene expression in the intestine of ulcerative colitis patients: a systematic review and meta-analysis

The mucus layer of the colon is the main barrier between luminal microbes and the mucosa, and plays a significant role in the body defense mechanisms. Several studies have examined mucin gene (MUC) expression in ulcerative colitis (UC) without conclusive results. The aim of the study was to establish the knowledge of mucin expression in UC as a basis for further investigation. English medical literature searches were performed for mucin expression in the colonic mucosa of UC patients in comparison with controls. Case-control studies were included. A meta-analysis was carried out using 'Comprehensive meta-analysis' software. Pooled odds ratios (ORs) and 95% confidence intervals were calculated. Altogether, we found 311 eligible studies. Only 10 case-control studies from five countries fulfilled the inclusion criteria. A moderate heterogeneity was found in the studies included: Q=52.703, d.f. (Q)=15.000, I=71.539%. OR for mucin expression in UC patients versus healthy controls was 1.868 with a 95% confidence interval (CI) 1.263-2.764, P=0.002. Thus, we could find a significant increase of 87% of mucin expression in UC patients. OR for MUC2 was 2.520, 95% CI 1.320-4.809, P<0.001. MUC3 was also increased with OR 2.599, 95% CI 1.389-4.861, P=0.003. Funnel plot did not indicate a significant publication bias. We found a global increase in mucin expression in UC patients, specifically in MUC2 and MUC3. Further studies are needed, especially in patients treated with biologics for mucosal healing, to understand the role of mucin expression in the natural history of UC.