Helicobacter pylori infection may help combat lower GI tract inflammation
MedWire News: Researchers have found that Helicobacter pylori infection reduces lower gastrointestinal tract inflammation caused by Salmonella typhimurium infection in mice.
"This research demonstrates that having H. pylori in your stomach could have beneficial immune effects in other parts of the body," said lead researcher Peter Higgins from the University of Michigan in Ann Arbor, USA. "If we have evolved to live with certain bugs, maybe there is a reason."
Higgins and team infected mice with a mouse-adapted strain of H. pylori (SS1), S. typhimurium, or both (H. pylori followed by S. typhimurium 1 month later) to assess the effects of H. pylori infection on S. typhimurium-induced colitis and the systemic immune response.
They found that H. pylori suppressed the T-helper cell (Th)17 reaction to S. typhimurium infection in the mouse cecum. In contrast, the Th2 and T-regulatory responses were not altered, and neither was the development of fibrosis.
Mice infected with both strains of bacteria had significantly decreased inflammation in the cecum and stomach compared with those infected with one strain only.
Infection of the mice with H. pylori lead to induction of interleukin 10 in the mesenteric lymph nodes, suggesting a mechanism for immune modulation occurring outside the stomach.
"This was surprising because H. pylori infects the stomach, not the colon. It appears to have a more global effect on the gut immune system," said study co-author John Kao, also from the University of Michigan.
"But it may explain why people in regions with lots of H. pylori infection - such as Asia and Africa - get fewer inflammatory bowel diseases, like ulcerative colitis and Crohn's disease," he added.
Higgins said that while he would not recommend that inflammatory bowel disease patients be infected with H. pylori, there may be a reason why it is so widespread.
"Maybe we should not be so quick to get rid of it in patients who do not have stomach ulcers," he suggested, especially in countries where S. typhimurium infection is common.
He commented: "It would be reasonable for researchers to look at whether H. pylori infection is associated with reduced severity of other gut infections like cholera or Clostridium difficile. Many more studies are needed, however, to see if H. pylori could actually prevent inflammatory bowel disease."
The results of this study are published in the journal Inflammatory Bowel Diseases.
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By Helen Albert