Warning Signs in the Blood Could Predict Inflammatory Bowel Disease a Decade Before Diagnosis, Research Suggests

The onset of inflammatory bowel disease, or IBD, could be predicted from patterns of antibodies in the blood as much as a decade before diagnosis, according to new research that raises hopes of identifying people at risk early enough to treat them sooner.

The two main forms of IBD are Crohn's disease and ulcerative colitis, conditions in which the digestive tract becomes chronically inflamed. At present they are typically treated only after symptoms appear, by which time the gut has already been damaged. The new research suggests the disease process begins far earlier than that.

At least 3.8 million people worldwide live with IBD. The condition causes pain, diarrhoea and fatigue. Its exact cause is unknown, although a misfiring immune system, genetics and the microbes living in the gut can all contribute.

Treatment relies on anti-inflammatory and immune-suppressing drugs, but many patients do not respond, and a significant number go on to have surgery to remove damaged sections of bowel. Longstanding inflammation also raises the risk of bowel cancer, which has prompted scientists to look for the earliest signs of the disease in the hope of identifying people at risk before damage begins.

The study was led by Dr Arno Bourgonje, of the University Medical Centre Groningen in the Netherlands and the Icahn School of Medicine at Mount Sinai in New York, working with colleagues at Mount Sinai and the Medical University of Vienna. The team ran tests on blood samples taken from US military personnel.

They examined 2,000 samples from 500 people. Of those, 200 later developed Crohn's disease and 200 went on to develop ulcerative colitis, while the remaining 100 developed neither condition. The samples were screened for antibodies the immune system might have produced in response to hundreds of thousands of fragments of proteins from bacteria, viruses, food and even the body's own tissues.

In people who went on to develop Crohn's disease, antibodies against the 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. In other words, the immune system appears to leave distinct early fingerprints for the two different forms of the disease.

Dr Bourgonje said that for too long it had only been possible to treat inflammatory bowel disease once the damage was done, which for many people was too late. He said the work showed the disease begins years before symptoms appear and that the immune system leaves warning signs long before diagnosis. He was clear, however, that this is not yet a test that can tell someone they will become ill; it is an important step towards catching the disease earlier and, one day, preventing it.

The findings were published in the journal Gut and presented at the United European Gastroenterology meeting in Barcelona. The researchers say the results need to be confirmed in other groups of people, and that they show a link rather than proving that infections cause IBD.

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. But he cautioned that the techniques were very much a research tool and not yet ready for the clinic.

Marianne Radcliffe, chief executive of the patient charity Crohn's & Colitis UK, said research of this kind was an important step forward for people affected by the conditions, with every new insight building a clearer understanding of how they develop, including changes that may occur years before symptoms appear. 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.