Crohn's Disease Associated With Microbiome Imbalance In The Gut
March 13, 2014

Crohn’s Patients Have Imbalance In Intestinal Microbial Population

Lee Rannals for - Your Universe Online

Researchers writing in the journal Cell Host & Microbe say they have found how the intestinal microbial population of newly diagnosed Crohn’s disease patients is different from other individuals.

The team says that Crohn’s patients showed increased levels of harmful bacteria and reduced levels of the beneficial bacteria usually found in a healthy gastrointestinal tract.

The research included data from the RISK Stratification Study, which investigated microbial, genetic and other factors in a group of children newly diagnosed with Crohn’s disease or other inflammatory bowel diseases.

During the study, samples of intestinal tissues were taken from 447 participants with a clear diagnosis of the disease at 28 participating centers in the US and Canada. The study also included 221 control participants with noninflammatory gastrointestinal conditions.

The team performed advanced sequencing of the microbiome in the tissue samples at the beginning and end of the large intestine and found a significant decrease in diversity in the microbial population of the Crohn’s patients. The samples revealed an abnormal increase in the proportion of inflammatory organisms in Crohn’s patients and a drop in inflammatory species.

"These results identifying the association of specific bacterial groups with Crohn's disease provide opportunities to mine the Crohn's-disease-associated microbiome to develop diagnostics and therapeutic leads," senior author Ramnik Xavier, MD, PhD, chief of the Massachusetts General Hospital Gastrointestinal Unit and director of the MGH Center for the Study of Inflammatory Bowel Disease, said in a statement.

The study also revealed that the bacterial communities in biopsies taken from rectal tissues served as good indicators of disease, regardless of where a patient experienced inflammation.

"This finding is particularly encouraging because it creates the opportunity to use a minimally invasive approach to collecting patient samples for early disease detection," first author Dr. Dirk Gevers of the Broad Institute said in a statement.

The authors said antibiotics are often prescribed for symptoms suggestive of Crohn’s before a diagnosis is made. However, the study found that participants taking antibiotics at the time samples were taken had an even more pronounced microbial imbalance, suggesting that antibiotics could exacerbate symptoms rather than relieve them.

Next, the team plans to uncover the functions of these microbes and their products and learn how the microbiome and microbial products interact with the patient’s immune system.

"Identifying which microbial products are key to disease onset and to inflammation resolution in inflammatory bowel disease and establishing which can be effectively targeted are our best hope to uncover the first microbiome-based therapies in IBD,” says Xavier.