Bacteria With Bad Rap Proves Protective

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If you’ve visited a doctor’s office with stomach complaints in recent years, it’s likely you were tested for H. pylori, an ancient bacterium that has survived for decades in the mucous layer of the stomach lining. Because of better sanitation and widespread use of antibiotics, H. pylori is not as prevalent in developed countries; and it actually may have some positive benefits for its human hosts.

Previous studies confirmed the bacterium’s link to gastric diseases ranging from gastritis to stomach cancer. However, recent research performed at NYU School of Medicine by Ye Chen, Ph.D., associate professor of population health and environmental medicine, and Martin J. Blaser, M.D., professor of internal medicine and professor of microbiology, has shown that H. pylori may be protective against childhood asthma. It’s more virulent strain (cagA) may even guard against death from lung cancer.

“We found that H. pylori is not related to the risk of death from all causes, despite it being related to increased risk of death from gastric cancer,” Chen said.

“This finding confirms earlier work, however, that gastric cancers are now uncommon in the United States. We also found that H. pylori was related to a reduced risk of stroke and lung cancer, and these effects were stronger for the cagA strain, suggesting its mixed role in human health.”

In the study, participants who were cagA-positive had a 55 percent reduction in death risk from stroke. This group also had a 45 percent reduced risk of death from lung cancer.

“The most interesting finding was that there is a strong inverse association with stroke which could be protective,” Blaser said. “There is some precedent for this and it is possible that the same cells (T reg cells) that H. pylori induces that protect against childhood asthma could be the protective agents, however, the findings need to be confirmed.”