Clinical Value of Anti-Integrin αvβ6 Antibody Serum-Level Measurement in Inflammatory Bowel Diseases

Background/Objectives: Differential diagnosis between Crohn's disease (CD) and ulcerative colitis (UC) can be sometimes difficult resulting in the diagnosis of unspecified inflammatory bowel diseases (IBD-U). Data suggest that IgG antibodies against integrin αvβ6 (V6 Ab) help to identify UC patients. Recent studies suggest that measuring V6 Ab serum levels may be valuable for differential diagnostic purposes. The primary objective of the study was to assess the sensitivity and specificity of V6 Ab serum-level measurement in our IBD population to differentiate between colonic/ileocolonic CD and UC with an established diagnosis. Furthermore, we assessed the correlation between disease characteristics, activity and V6 Ab serum levels in UC patients. Methods: Consecutive IBD patients with an established diagnosis undergoing control colonoscopy in a tertiary IBD center were included. Baseline demographic data, current treatment, disease extent, clinical, biomarker, endoscopic and histologic disease activity were collected. V6 Ab serum levels were measured with the Anti-Integrin αvβ6 ELISA Kit (RUO). Patients' written informed consent was obtained. Results: A total of 40 IBD patients, including 10 CD and 30 UC patients (15 with clinical activity and 15 in clinical remission) were enrolled. V6 Ab serum levels were significantly higher in UC patients compared to CD (p = 0.039). ROC analysis found 1.33 U/mL to be the best cut-off level (p = 0.04; AUC: 0.71) with 100% sensitivity and 50% specificity and a positive predictive value of 85.7% and a negative predictive value of 100% to differentiate between UC and CD. No significant correlation was found between V6 Ab serum levels and CRP (p = 0.057), fecal calprotectin (p = 0.77), endoscopic activity (p = 0.624) or disease extent (p = 0.624) in UC patients. Conclusions: Our study supports the value of V6 Ab serum level measurement as a differential diagnostic tool in IBD patients; however, the optimal cut-off value is yet to be determined. Our data do not support its role in disease activity monitoring.