Inhibition of gastric mucin synthesis by Helicobacter pylori

Background & Aims: Mucins are high-molecular-weight glycoproteins that prot ect the gastric epithelium. Previous data suggested that gastric surface-ty pe mucin is decreased in Helicobacter pylori-infected patients and restored after eradication of the infection. Our aim was to determine the effect of H. pylori on mucin synthesis in cultured gastric epithelial cells. Methods : Mucin synthesis was measured by labeling with [H-3]glucosamine and size-e xclusion chromatography, Expression of MUC5AC and MUC1 mucin protein antige ns was quantitated by Western blot analysis, Results: Mucin synthesis was i nhibited more than 80% when KATO III cells were incubated with H. pylori, w ith no effect on mucin secretion or degradation, Inhibition was rapid (4 ho urs), partially reversible, dependent on concentration of bacteria, and ass ociated with the insoluble membrane fraction. H. pylori decreased levels of MUC5AC and MUC1 mucins, MUC1 inhibition was half-maximal by 4 hours and pa rtially reversed by 24 hours, but the decrease in MUC5AC was less rapid and not reversible within 24 hours, Conclusions: H, pylori inhibits total muci n synthesis in vitro and decreases the expression of MUC5AC and MUC1, A dec rease in gastric mucin synthesis in vivo may disrupt the protective surface mucin layer.