What do bacteria have to do with Crohn’s?
Changes in the gut microbiome have long been linked with Crohn’s disease and other forms of inflammatory bowel disease (IBD), but the biology behind those links has remained murky. Researchers at the Broad Institute, Massachusetts General Hospital (MGH), and Harvard Medical School (HMS) have now found that one bacterium, Ruminococcus gnavus, which is associated with Crohn’s disease, releases a certain type of polysaccharide (or a chain of sugar molecules) that triggers an immune response.
This study, published in the Proceedings of the National Academy of Sciences, is one of the first studies to delve into the mechanisms underlying a well-known association between a gut microbe and human disease.
“This is a distinct molecule that represents the potential link between gut microbes and an inflammatory disease,” said first author Matthew Henke, a postdoctoral fellow in the laboratory of study corresponding author and Broad Institute senior associate member Jon Clardy of Harvard Medical School.
“More and more studies on the correlations between the bacteria in the microbiota and disease were coming out,” said Clardy, who is the Hsien Wu and Daisy Yen Wu Professor of Biological Chemistry and Molecular Pharmacology at HMS. “Some were very strong, some were weak, but it was really all correlations.”
About 2 million Americans suffer from an inflammatory bowel disease (IBD), including Crohn’s. Previous work from the lab of Broad core institute member and Infectious Disease and Microbiome Program co-director Ramnik Xavier proved that during some flares of Crohn’s disease, the abundance of R. gnavus can jump from less than one percent of the gut microbiota to greater than 50 percent.
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