Effects of Helicobacter pylori infection on gastric mucin expression

Aims: This study was performed to determine the gastric distributions of MUC5AC and MUC6 depending on Helicobacter pylori (H. pylori) infection, and to evaluate whether the expressions of MUC5 and MUC6 change in H. pylori-associated gastroduodenal diseases. In addition, MUC5AC and MUC6 expressional changes were investigated before and after H. pylori eradication. Methods: In the 224 individuals (136 H. pylori-positive and 88 H. pylori-negative) who came from control (N = 48), duodenal ulcer (N = 35), benign gastric ulcer (N = 61), dysplasia, plus stomach cancer (N = 80) groups, MUC5AC and MUC6 expressions were determined by immunohistochemical staining in the antrum and body, respectively. This staining for MUC5AC and MUC6 were reperformed in 113 of the 136 H. pylori-positive patients after successful H. pylori eradication by proton pump inhibitor-based triple therapy. Results: (1) No difference was found between the H. pylori-positive and negative groups in terms of MUC5AC expression. In contrast, MUC6 expression was significantly lower in the H. pylori-positive group than in the H. pylori-negative group in the gastric body. Moreover, reduced MUC6 expression increased to the H. pylori-negative level after eradication. (2) Expressions of MUC5AC and MUC6 were significantly lower in the dysplasia plus cancer group than those of control in case of H. pylori positive. Similarly, MUC5AC and MUC6 expressions were significantly lower in the presence of atrophic gastritis with intestinal metaplasia in case of H. pylori positive. (3) Aberrant expressions of MUC6 in foveolar cells were observed in both antrum (11.3 %) and body (5.3 %) only in the H. pylori-positive group, but this reverted to normal after H. pylori eradication. Conclusion: These results suggest that H. pylori infection causes alterations of mucin expression, closely related with the development of gastric atrophy with intestinal metaplasia, probably contributing to carcinogenesis.