Anti-Integrin αvβ6 Autoantibodies Are a Novel Biomarker That Antedate Ulcerative Colitis

Abstract

Background & aims: Better biomarkers for prediction of ulcerative colitis (UC) development and prognostication are needed. Anti-integrin αvβ6 (anti-αvβ6) autoantibodies have been described in patients with UC. We tested for the presence of anti-αvβ6 antibodies in the preclinical phase of UC and studied their association with disease-related outcomes after diagnosis.

Methods: Anti-αvβ6 autoantibodies were measured in 4 longitudinal serum samples collected from 82 subjects who later developed UC and 82 matched controls from a Department of Defense preclinical cohort (PREDICTS [Proteomic Evaluation and Discovery in an IBD Cohort of Tri-service Subjects]). In a distinct, external validation cohort (Crohn's and Colitis Canada Genetic Environmental Microbial project cohort), we tested 12 pre-UC subjects and 49 matched controls. Furthermore, anti-αvβ6 autoantibodies were measured in 2 incident UC cohorts (COMPASS [Comprehensive Care for the Recently Diagnosed IBD Patients], n = 55 and OSCCAR [Ocean State Crohn's and Colitis Area Registry], n = 104) and associations between anti-αvβ6 autoantibodies and UC-related outcomes were defined using Cox proportional hazards model.

Results: Anti-αvβ6 autoantibodies were significantly higher among individuals who developed UC compared with controls up to 10 years before diagnosis in PREDICTS. The anti-αvβ6 autoantibody seropositivity was 12.2% 10 years before diagnosis and increased to 52.4% at the time of diagnosis in subjects who developed UC compared with 2.7% in controls across the 4 time points. Anti-αvβ6 autoantibodies predicted UC development with an area under the curve of at least 0.8 up to 10 years before diagnosis. The presence of anti-αvβ6 autoantibodies in preclinical UC samples was validated in the GEM cohort. Finally, high anti-αvβ6 autoantibodies was associated with a composite of adverse UC outcomes, including hospitalization, disease extension, colectomy, systemic steroid use, and/or escalation to biologic therapy in recently diagnosed UC.

Conclusions: Anti-integrin αvβ6 autoantibodies precede the clinical diagnosis of UC by up to 10 years and are associated with adverse UC-related outcomes.

Keywords: Anti-Integrin αvβ6; Autoantibodies; Biomarkers; Inflammatory Bowel Disease; Ulcerative Colitis.

Figure 1.

Anti-αvβ6 autoantibodies in preclinical subjects with UC. (A) Timeline of sample collection in the PREDICTS cohort from 82 subjects who developed UC and 82 matched controls (HC). Sample A was collected at the time of diagnosis for subjects with UC and samples B, C, and D were collected before diagnosis. Median (interquartile range [IQR]) time in years for samples A, B, C, and D are detailed for both UC and HC. (B) Anti-αvβ6 autoantibody absorbance values (OD450) determined by means of ELISA in UC (n = 82, shown in red) and HC (n = 82, shown in blue) sera obtained before diagnosis (samples B, C, and D) and at the time of diagnosis (sample A) from the PREDICTS cohort. In sample D, 1 HC sample was excluded due to an identification issue. For all boxplots, the box represents the IQR, the center line represents the median, and the whiskers indicate the minimum to maximum value. Statistical significance determined by means of conditional logistic regressions at each time point comparing subjects who developed UC with matched controls. (C) Dynamics of anti-αvβ6 in each HC or UC subject across the 4 longitudinal samples in the PREDICTS cohort. Purple lines represent samples that are positive for anti-αvβ6 in sample D, red lines indicate samples that seroconvert between sample D and A, and blue lines indicate subjects that are negative at all sample time points. (D) Anti-αvβ6 autoantibody levels as a function of UC disease extent as defined by Montreal classification (E1: proctitis only, n = 15; E2: left-sided disease, n = 12; E3: extensive disease, n = 32; unknown, n = 23) and (E) by age at diagnosis, shown as scatterplot in the PREDICTS cohort. Statistical significance determined by means of linear regression and Spearman correlation, respectively. (F) Predictive performance of anti-αvβ6 autoantibodies based on 10-fold cross-validation and the 95% CI of the AUC based on 10,000 bootstrap iterations in the PREDICTS cohort. Sample A (time of diagnosis) is in red, sample B (−2 years) is in purple, sample C (−4 years) is in light blue, and sample D (−10 years) is in dark blue. (G) Anti-αvβ6 autoantibody absorbance values (OD450) determined by means of ELISA in 12 pre-UC subjects and 49 matched control subjects from the GEM cohort. Statistical significance determined by conditional logistic regression comparing pre-UC subjects with matched control subjects.

Figure 2.

Anti-αvβ6 autoantibodies in patients with newly diagnosed UC and their association with adverse disease-related outcomes. (A) Anti-αvβ6 autoantibody absorbance values (OD450) determined by means of ELISA in non-IBD controls (n = 54, shown in blue), in COMPASS patients with UC (n = 55, shown in red), and in OSCCAR patients with UC (n = 104, shown in red). (B) ROC analysis of anti-αvβ6 autoantibodies in both COMPASS patients with UC (left) and OSCCAR patients with UC (right) compared with the non-IBD controls. (C, D) Kaplan-Meier curve for composite outcome of IBD hospitalization, proximal disease extension, need for surgery, systemic steroid use, and/or requiring new biologic therapy in the COMPASS cohort (C) and OSCCAR cohort (D) stratified by anti-αvβ6 titer tertiles. The blue line represents the first tertile (lowest), the gray line represents the second tertile, and the red line the third (highest) tertile. (E) Kaplan-Meier curve for the same composite outcomes in the OSCCAR cohort stratified according to the presence or absence of pANCA. (F) Spearman correlation between pANCA and anti-αvβ6 titers.