Researchers Uncover Bacterial Connection Between Crohn's Disease and Spondyloarthritis

It is not completely unexpected for patients who routinely suffer from abdominal discomfort and diarrhea associated with Crohn’s disease (CD) to experience severe joint pain.

Researchers from Weill Cornell Medicine (WCM) reported that CD affects nearly 800,000 people in the US. Prior studies established that the immune system in CD patients can attack the bowel, but new findings showed it could also assault the musculoskeletal system, leading to spondyloarthritis — a painful condition affecting the joints and spine.

Although the two medical conditions might seem unrelated, the research team used fecal samples from inflammatory bowel disease (IBD) patients to identify gut bacteria that were coated with infection-fighting antibodies called immunoglobulin-A (IgA). When the team later used fluorescent probes in flow cytometry, they discovered an abundance of IgA-coated Escherichia coli (E. coli) in the fecal samples of patients with both CD and spondyloarthritis.

The investigators were able to connect IgA-coated E. coli to Th17 cells that regulate inflammation — patients with CD and spondyloarthritis showed higher levels of Th17 cells triggered by IL-23 protein.

This discovery can allow physicians to easily identify CD patients who are likely to develop spondyloarthritis thus providing targeted treatment options sooner. Findings indicated that the key to shifting CD and spondyloarthritis into remission is starting from the root and preventing the bacteria from inducing inflammation.

According to Randy Longman, MD, assistant professor of medicine and director of the Jill Roberts Institute Longman Lab at WCM, “In IBD therapy, this is a step toward precision medicine — to be able to clinically and biologically characterize a subtype of disease and then select the medicine that would best fit the patient with this type of inflammation. The results of this innovative study will start to inform our decision of which of our available medications will give the best chance of helping the individual patient.”

The paper, “IgA-coated E. coli enriched in Crohn’s disease spondyloarthritis promote Th17-dependent inflammation,” was published in Science Translational Medicine.