Researchers have discovered how the bacterium Helicobacter pylori causes ulcers, and it is not what they expected. A team from Stanford University and the IRIS research institute in Siena, Italy, reported in Friday’s issue of Science that the bacterium binds to the junctions between cells in the intestinal lining, injecting a protein that loosens the binding between cells.
That causes leakiness of the lining, allowing stomach acids to irritate underlying tissue and produce ulcers. About 80% of ulcers are caused by the bacterium. The rest are caused primarily by aspirin and other pain relievers.