Antibody Profiles Predict IBD Up to 10 Years Before Diagnosis

Blood tests could spot Crohn’s disease and ulcerative colitis up to ten years before clinical symptoms emerge, according to research presented at the United European Gastroenterology congress, UEGW Week 2026, in Barcelona.

The study analyzed 2,000 serum samples from 500 adults. Researchers tracked immune activity over a decade by examining samples taken at diagnosis and two, four, and ten years prior.

Participants who later developed inflammatory bowel disease had fewer types of antibodies than healthy control subjects.

Crohn’s disease and ulcerative colitis displayed distinct immune signatures. In Crohn’s patients, responses against encapsulated bacteria decreased over time. Meanwhile, antibody levels against herpesviruses and flagellin—a protein used by certain bacteria for locomotion—increased progressively.

These immune shifts were especially pronounced in adults who developed complicated Crohn’s disease or ileal involvement affecting the final section of the small intestine. Il ne s’agit donc pas simplement d’une conséquence de l’évolution de la maladie après le diagnostic, noted Arno Bourgonje.

Participant Group	Sample Count	Key Immune Changes Observed
Crohn’s Disease	200 Adults	Decreased anti-bacterial responses; elevated anti-herpesvirus and anti-flagellin antibodies up to 10 years prior.
Ulcerative Colitis	200 Adults	Elevated anti-herpesvirus and auto-antibody levels; reduced responses against encapsulated pathogens.
Healthy Controls	100 Adults	Higher overall antibody diversity and stable baseline immune markers across matched ages.

Ulcerative colitis followed a different immunological trajectory across the same ten-year window.

Auto-antigens are components of the body’s own tissues that mistakenly become the target of an immune attack. Conversely, responses directed against encapsulated pathogens dropped steadily in the ulcerative colitis cohort.

Researchers identified 123,980 unique antibodies across all serum samples by testing reactivity against roughly 357,000 antigens. Antigens are substances that the immune system recognizes and reacts against, while antibodies are proteins produced to target specific threats.

While the retrospective findings map a clear decade-long preclinical window, clinical translation remains incomplete. Investigators emphasize that prospective validation in independent, diverse populations is necessary before any routine diagnostic test can be built.

La prochaine priorité consiste à valider ces signatures au sein de populations indépendantes, plus diversifiées et suivies de manière prospective, stated Arno Bourgonje regarding the roadmap for clinical deployment. Scientists must also establish whether these antibody profiles outperform existing genetic and standard blood markers in cost-effective screening tools.

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• United European Gastroenterology (UEG) – UEGW Week 2026 Congress Proceedings, Barcelona.