Natural antibiotic function of a human gastric mucin against Helicobacter pylori infection

Helicobacter pylori infects the stomachs of nearly a half the human population, yet most infected individuals remain asymptomatic, which suggests that there is a host defense against this bacterium. Because H. pylori is rarely found in deeper portions of the gastric mucosa, where O -glycans are expressed that have terminal α1,4-linked N -acetylglucosamine, we tested whether these O -glycans might affect H. pylori growth. Here, we report that these O -glycans have antimicrobial activity against H. pylori , inhibiting its biosynthesis of cholesteryl-α-D-glucopyranoside, a major cell wall component. Thus, the unique O -glycans in gastric mucin appeared to function as a natural antibiotic, protecting the host from H. pylori infection.