Researchers detect antibody changes 10 years before inflammatory bowel disease diagnosis — ScienceDaily

Researchers have identified changes in the immune system that can be detected in blood ten years before a diagnosis of inflammatory bowel disease is made. The findings were presented on October 19 at UEG Week 2026 in Barcelona, Spain, ScienceDaily reports. The conditions include Crohn’s disease and ulcerative colitis — chronic disorders associated with persistent inflammation of the digestive tract.

Analysis of samples over ten years

Scientists analyzed 2,000 blood serum samples from 500 people. The cohort included 200 participants who were later diagnosed with Crohn’s disease, 200 people who developed ulcerative colitis, and 100 healthy participants matched by age and sex.

Samples were available for participants from the time of diagnosis, as well as from approximately two, four, and ten years before it. The team examined antibody responses to about 357,000 antigens associated with bacteria, viruses, food, and the immune system. In total, 123,980 unique antibodies were identified in the samples.

People who later developed the diseases had lower antibody diversity than healthy participants. Distinct immune signatures for both diseases were detected as early as ten years before diagnosis.

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Different disease signatures

People who were later diagnosed with Crohn’s disease had elevated antibody responses to herpesviruses and bacterial flagellin — a protein that is part of the flagella structure of some bacteria. This feature was particularly pronounced in participants who had complicated Crohn’s disease or ileal involvement at the time of diagnosis. At the same time, responses to encapsulated bacteria declined as diagnosis approached.

For ulcerative colitis, researchers recorded a different profile: increased responses to herpesviruses and autoantigens, as well as weakened responses to encapsulated pathogens. Machine-learning models based on an antibody profile obtained up to ten years before diagnosis distinguished future Crohn’s disease cases from the healthy control group with an AUC of 0.90, and ulcerative colitis with an AUC of 0.84. The AUC was 0.85 for distinguishing future cases of complicated Crohn’s disease from less complicated cases.

The authors emphasized that the method is not yet ready for routine screening. The next step should be to verify the results in independent, more diverse groups and to assess the usefulness of such testing alongside genetic, clinical, and other blood markers.