Scientists have identified immune system changes that appear up to a decade before inflammatory bowel disease is diagnosed, raising hopes for earlier detection and treatment. The findings, presented at UEG Week 2026, suggest that distinct antibody patterns in the blood could help identify people at risk of developing Crohn’s disease or ulcerative colitis and even predict disease severity.
Researchers examined 2,000 blood serum samples from 500 people: 200 who eventually developed Crohn’s disease, 200 who developed ulcerative colitis, and 100 healthy controls. Samples were available from diagnosis and from approximately two, four and 10 years earlier, allowing the team to track immune changes over time.
The analysis detected antibody reactions to approximately 357,000 antigens associated with bacteria, viruses, food and the immune system itself. People who later developed IBD had significantly less antibody diversity than healthy participants, with distinctive changes detectable as far back as 10 years before diagnosis.
Crohn’s disease and ulcerative colitis showed different immune signatures. Those who later developed Crohn’s had elevated antibody responses to herpesviruses and bacterial flagellin, particularly those who developed complicated disease. Ulcerative colitis showed increased responses to herpesviruses and autoantigens.
Using machine learning, researchers distinguished future Crohn’s disease cases from healthy controls with an area under the curve of 0.90, and ulcerative colitis with 0.84. The models could also identify those who would develop complicated Crohn’s disease approximately 10 years before diagnosis.
The researchers emphasise that additional validation in diverse populations is needed before these findings could inform clinical screening.
Source: Bourgonje AR et al. Deciphering the prodrome of inflammatory bowel disease up to 10 years before disease onset by massively parallel serology. Presented at UEG Week 2026.
