Blood antibody patterns may signal inflammatory bowel disease a decade before diagnosis

Crohn’s disease and ulcerative colitis, the two main forms of IBD, are typically treated only after symptoms appear, when the gut has already been damaged. Scientists found that the immune system sends warning signals up to a decade before diagnosis, according to the study published in the journal Gut and presented at the United European Gastroenterology meeting in Barcelona.

“For too long we have only been able to treat inflammatory bowel disease once the damage is done, and for many people that is too late,” said Dr Arno Bourgonje at the University Medical Centre Groningen in the Netherlands and the Icahn School of Medicine at Mount Sinai in New York. “What we have shown is that the disease begins years before symptoms appear, and the immune system leaves warning signs long before diagnosis. This is not yet a test that can tell someone they will become ill, but it is an important step towards catching the disease earlier and, one day, preventing it.”

At least 3.8 million people worldwide live with IBD, an immune condition that causes chronic inflammation of the digestive tract, leading to pain, diarrhoea and fatigue. Its exact cause is unknown, but a misfiring immune system, genetics and gut microbes can all contribute. Treatment relies on anti-inflammatory and immune-suppressing drugs, but many patients do not respond, and a significant number have surgery to remove damaged bowel. Longstanding inflammation also raises the risk of bowel cancer.

Bourgonje and colleagues at Mount Sinai and the Medical University of Vienna tested blood samples taken from US military personnel. They examined 2,000 samples from 500 people, including 200 who later developed Crohn’s disease, 200 who developed ulcerative colitis and 100 who developed neither condition. The samples were screened for antibodies that the immune system might have produced in response to hundreds of thousands of protein fragments from bacteria, viruses, food and the body’s own tissues.

In people who later developed Crohn’s disease, antibodies against Epstein-Barr virus, which causes glandular fever, were more common, and the differences were already visible a decade before diagnosis. The signal was strongest in those who later developed more severe, complicated disease, which can narrow the bowel or create abnormal channels. People who developed ulcerative colitis showed a different pattern, including antibodies against one of the body’s own proteins.

The findings need to be confirmed in other groups of people, and the results show a link rather than proving that infections cause IBD. The hope is that IBD could eventually follow the path of type 1 diabetes, where a blood test can identify people whose immune systems have begun attacking the pancreas before symptoms appear, allowing treatment that delays the onset of disease.

James Lindsay, a professor of gastroenterology at Barts Health, who was not involved in the research, said the study provided “important insights into the causes of Crohn’s disease and ulcerative colitis, potentially adding new tools to help identify those at risk of IBD”. He cautioned that the techniques were “very much a research tool” and not yet ready for the clinic.

Marianne Radcliffe, chief executive of Crohn’s & Colitis UK, a national patient charity, said: “For people affected by Crohn’s and colitis, research like this is an important step forward. Every new insight helps build a clearer understanding of how these conditions develop, including the changes that may occur years before symptoms appear.”