Abundant Gut Bacteria in Crohn's Disease Linked to Spondyloarthritis

High levels of a type of E. coli found in patients with Crohn’s disease triggers inflammation associated with spondyloarthritis, according to a study published in Science Translational Medicine.

For the study, the investigators used flow cytometry to examine gut bacteria in fecal samples derived from patients with inflammatory bowel disease (IBD). Flow cytometry is a technology that uses fluorescent probes to detect immunoglobulin-A (IgA)-coated bacterial species.

The investigators discovered that IgA-coated E. coli were abundant in the fecal samples of patients with both Crohn’s disease and spondyloarthritis. Next, they used patient samples and mouse models to link the bacteria to Th17 cells, which help regulate inflammation in individuals with autoimmune disorders.

“Our findings may allow us to develop diagnostic tools to stratify Crohn’s patients with spondyloarthritis symptoms as well as patients at risk,” said senior author Dr Randy Longman.

The results of the study showed patients with Crohn’s disease and spondyloarthritis had higher levels of TH17 cells and the protein IL-23, which triggers disease activity.

The authors noted that the findings may help physicians choose therapies that target symptoms of both the bowels and joints in this patient population.

“Just sequencing the gut flora gives you an inventory of the bacteria, but does not tell you how they are perceived by the host immune system,” said co-author Dr Kenneth Simpson. “This approach is giving you a functional readout versus just an inventory.

“We knew there was smoke but we didn’t know where the fire was. If we can block the ability of bacteria to induce inflammation, we may be able to kick Crohn’s disease and spondyloarthritis into remission.”

Spondyloarthritis is a type of arthritis that attacks the spine and joints, and can even affect the eyes, intestines, and skin, according to the American College of Rheumatology. Individuals in their teens and 20s—–especially males––are most often affected.

“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,” Dr Longman said. “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.”