Discovery Could Lead to New Inflammatory Bowel Disease Treatments

Bacterial enzyme could offer new target for treatment of condition.

Recent insight into the association between bacteria and immune cells in inflammatory bowel disease (IBD) could lead to new treatments for conditions like Crohn’s Disease and ulcerative colitis.

Microbes in the gut are mostly beneficial, however some bacteria can penetrate the protective layer of mucus covering the inner lining of the gut. Prior research hypothesized under certain conditions these bacteria burrow into the gut lining, which incites immune cells to attack and damage the intestine.

Published May 13 in Cell Host & Microbe, the study found particular bacteria produce small particles that can penetrate gut lining and produce an aggressive immune system response.

"You can compare these particles, which are known as vesicles, to fighter jets being released from a bacterial mothership," study co-author Chistina Hickey, MD, said in a press release. "Having a more accurate picture of how these jets trigger the onset of an attack should help us devise better ways to help prevent IBD symptoms."

The researchers genetically altered mice to develop a condition similar to early onset IBD. IBD, which causes more severe symptoms in adults, is frequently caused by rare genetic mutations.

The researchers evaluated the Bacteroides thetaiotaomicron bacterial species that causes colon inflammation in mice as it degrades the mucus lining the gut interior. This allows bacteria to encounter immune cells in gut tissue and incite an immune response that leads to the intestinal inflammation that characterizes IBD.

Surprisingly, the researchers found bacteria remains in the gut as vesicles produced by the bacteria enter the gut tissue. These vesicles interact with the immune cells after moving from the bacteria into the host tissue.

"The immune cells don't need to encounter the bacteria to cause inflammation -- all they need to do is encounter the vesicles," said co-author Thad Stappenbeck, MD, PhD, in a press release. "We didn't realize that was possible, and we think this discovery could change our thinking about not just IBD but other autoimmune disorders and infectious diseases."