Israel Medical Association Journal

Mucin gene 5AC (MUC5AC), a secreted mucin, is the most important component of the gastric mucus unstirred, protecting layer, preventing the enzymatic attack of acid and pepsin, toxins, and microorganisms. We investigated the effect of Helicobacter pylori (H. pylori) infection on MUC5AC expression in the gastric mucosa. English language medical literature searches were conducted for gastric MUC5AC expression in H. pylori infected patients compared to uninfected people, or cases after eradication. PubMed, EMBASE, Scopus, and CENTRAL databases were searched. Meta-analysis was performed and pooled odds ratios (ORs) and 95% confidence intervals (95%CIs) were calculated. Heterogeneity was evaluated and I² statistic was used to measure the proportion of inconsistency in individual studies.

We also calculated a potential publication bias. In all, 11 studies representing 13 sub-studies were selected according to the inclusion criteria. The OR of MUC5AC expression in a random effect analysis was 0.217, 95%CI 0.124–0.377, P < 0.0001, significantly lower in H. pylori gastritis than in normal mucosa. When only studies with high-quality scores were calculated, OR was 0.239, 95%CI 0.137–0.419, P < 0.0001. Heterogeneity and inconsistency were small, with no significant publication bias. MUC5AC expression is lower in H. pylori infected mucosa, which may significantly affect the effective colonization and survival of the bacterium and persistent chronic inflammation.

Background: Mucins, heavily glycosylated glycoproteins, are synthesized by mucosal surfaces and play an important role in healthy and malignant states. Changes in mucin synthesis, expression, and secretion may be a primary event or may be secondary to inflammation and carcinogenesis.

Objectives: To assess current knowledge of mucin expression in the small bowel of celiac disease (CD) patients and to determine possible associations between mucin profile and gluten-free diet.

Method: Medical literature searches of articles in English were conducted using the terms mucin and celiac. Observational studies were included. Pooled odds ratios and 95% confidence intervals were calculated.

Results: Of 31 articles initially generated by a literature search, 4 observational studies that fulfilled the inclusion criteria remained eligible for meta-analysis. These studies included 182 patients and 148 controls from four countries (Finland, Japan, Sweden, United States). Mucin expression was significantly increased in small bowel mucosa of CD patients than in normal small bowel mucosa (odds ratio [OR] 7.974, 95% confidence interval [95%CI] (1.599–39.763), P = 0.011] (random-effect model). Heterogeneity was significant: Q = 35.743, df (Q) = 7, P < 0.0001, I² = 80.416%. ORs for MUC2 and MUC5AC expression in the small bowel mucosa of untreated CD patients were 8.837, 95%CI 0.222–352.283, P = 0.247 and 21.429, 95%CI 3.883–118.255, P < 0.0001, respectively.

Conclusions: Expression of certain mucin genes in the small bowel mucosa of CD patients is increased and may serve as a diagnostic tool and assist in surveillance programs.