Long before the first stomach cramps, the immune system may already be giving away that something is wrong in the gut. Researchers reported at Europe’s big gastroenterology meeting in Barcelona that distinctive antibody signatures show up in blood as much as ten years ahead of an inflammatory bowel disease (IBD) diagnosis.
More than 3.8 million people around the globe live with one of its two main types, Crohn’s or ulcerative colitis. Doctors usually start treatment only once symptoms appear, by which point the bowel is often already damaged.
To look further back in time, a team led by Arno Bourgonje of Groningen’s university hospital and New York’s Icahn School of Medicine turned to stored blood drawn from American service members. Of the 500 people included, 400 eventually fell ill, split evenly between the two conditions, while 100 served as a healthy comparison group. For each, four samples were available, taken at diagnosis and about two, four and ten years earlier. Every sample was screened against roughly 357,000 fragments of microbes, viruses, foods and human proteins.
Future patients had a narrower range of antibodies than healthy people. Those heading for Crohn’s reacted more strongly to herpesviruses such as Epstein-Barr and to bacterial flagellin, especially when their disease later turned severe. Colitis patients, by contrast, more often carried antibodies aimed at their own tissue. A machine-learning model separated future patients from healthy controls with high accuracy, scoring 0.90 for Crohn’s and 0.84 for colitis on a scale where 1 is perfect.
Bourgonje is careful not to oversell it: a diagnostic test for healthy people is still some way off, he says. The signatures must now be confirmed in larger, more diverse groups, and the results show associations rather than causes. Independent gastroenterologists also see it as a lab method for now, not a clinical tool. The long-term dream is a screening approach like in type 1 diabetes, where antibody tests can reveal an autoimmune attack years before illness sets in.
