A stomach bacterium believed to cause health problems such as gastritis, ulcers, and gastric cancer may play a dual role by balancing the stomach's ecosystem and controlling body weight and glucose tolerance, according to immunologists at the Virginia Bioinformatics Institute of Virginia Tech.
Usually the villain in studies of gastric cancer and peptic ulcers, Helicobacter pylori infect about half of the world's population although most infected individuals don't get sick. The bacterium's dwindling numbers coincide with the epidemic of obesity and diabetes in developed countries.
"H. pylori is the dominant member of the gastric microbiota and infects about half of the world population. While H. pylori infection can be associated with severe disease, it helps control chronic inflammatory, allergic, or autoimmune diseases," said Josep Bassaganya-Riera, director of the Nutritional Immunology and Molecular Medicine Laboratory and the Center for Modeling Immunity to Enteric Pathogens (MIEP) at Virginia Tech. "We demonstrated for the first time that gastric colonization with H. pylori exerts beneficial effects in mouse models of obesity and diabetes."
During the past 20 years, obesity in the United States has increased dramatically, according to the Centers for Disease Control and Prevention. About 36 percent of U.S. adults and approximately 17 percent of young people aged 2 to 19 years are obese. Obesity is the leading risk factor for type 2 diabetes and the rates of diabetes have increased in parallel with the rates of obesity.
Mice infected with H. pylori showed less insulin resistance than uninfected mice or other mice infected with a more virulent strain of H. pylori, according to the study, which was recently published in PLOS One. Researchers believe that whether the infection is harmful or beneficial depends on the interaction between the genetic makeup of H. pylori and the host's immune response.
H. pylori carrying the cytotoxin-associated gene pathogenicity island were harmful. But the bacteria with or without an atypical island may be integral to human stomach microbiota. Indeed, studies show that humans have been colonized by H. pylori for about 116,000 years.