P889 Serologic response with antimicrobial antibodies during the preclinical phase of inflammatory bowel disease

Abstract

Abstract Background Previous data have shown that the inflammatory process underlying ulcerative colitis (UC) and Crohn’s disease (CD) can start years before the diagnosis. Serum proteomic and serologic markers have been identified during this period, providing the opportunity for early detection of the initial immune disturbances. Our aim was to determine if patients with an incidental diagnosis of UC or CD demonstrate a serologic response based on antimicrobial antibodies, therefore preceding the symptomatic onset of the disease. Methods We performed a prospective single-center study including all asymptomatic subjects with a diagnosis of UC or CD during the colorectal cancer screening program and available data on antimicrobial antibodies between 01/10/2013 – 29/02/2022. The diagnosis of IBD was established by a combination of clinical data, endoscopic findings suggestive of UC or CD, and after histologic confirmation. ASCA IgA, ASCA IgG (EliA ASCA IgA/IgG, ThermoFisher) and ANCA (EUROPattern, PerkinElmer; EliA IgG, ThermoFisher) antibodies were determined. Positive results were considered above 10 U/mL for ASCA, 3.5 for ANCA-MPO and 2.00 for ANCA-PR3. Descriptive statistics were used. Results A total of 26 incidentally-diagnosed patients were included, 19 with UC (21% left-sided, 32% extensive; 53% former smokers), and 7 with CD (57% ileal, 29% colonic; 14% active smokers), with a median age of 51 years (IQR, 51-57). Three patients showed at least one positive test (12%). One patient (5%) with extensive UC showed positive ANCA results, and he developed symptoms 2 months after diagnosis. Two patients (28%) with CD (L2B2 and L1B1, according to Montreal classification) showed positivity to ASCA IgA/IgG at diagnosis, and both have remained asymptomatic after a median of 23 months. After a median follow-up of the whole cohort of 54 months (IQR, 26-67), 12 patients (46%) developed symptomatic disease. Conclusion A low proportion of patients with an incidental diagnosis of IBD demonstrate a serological response based on antimicrobial antibodies, suggesting that this situation corresponds to the initial phases of IBD when systemic immune disturbances might not be detectable yet.