Antibodies against glycoprotein 2 are novel markers of intestinal inflammation in patients with an ileal pouch

Background and aims: The Crohn's disease (CD)-specific pancreatic auto-antibodies (PAB), have been recently identified to target glycoprotein 2 (GP2). Pouchitis is an inflammation of the small bowel developing in up to 60% of ulcerative colitis patients undergoing proctocolectomy and ileal pouch anal anastomosis. Occurrence of CD-specific antibodies was reported to be a predictor of pouchitis. We aimed to assess the prevalence of anti-GP2 antibodies (anti-GP2) in the serum and feces of pouch patients and to correlate them with clinical parameters. Furthermore, we examined mucosal expression of the GP2 protein in the pouch. Methods: Pouch patients were prospectively recruited and checked for clinical, endoscopic, and laboratory markers of inflammation. IgG and IgA anti-GP2 levels in serum and fecal samples were determined using ELISA. GP2 protein was assessed by immunohistochemistry. Results: Anti-GP2 was elevated in both serum and fecal samples of patients with inflamed compared to those with non-inflamed pouches and patients with familial-adenomatous polyposis after surgery (p < 0.05, respectively). Moreover, patients with CD-like complications exhibited significantly higher anti-GP2 titers than those without CD-like complications (p ≤ 0.01). High levels of anti-GP2 correlated with more frequent bowel movements per day and with the presence of at least one anti-glycan antibody (p ≤ 0.05). GP2 itself was more abundant in the mucosa of patients with chronic pouchitis. Conclusions: Anti-GP2 exists in the serum and feces of pouch patients and correlates with pouch inflammation, and presence of other serological markers. Thus, anti-GP2 may contribute to better stratification of pouchitis, more-so when the inflammation exhibits CD-like complications. * Abbreviations : ACCA : anti-chitobioside carbohydrate antibodies ALCA : anti-laminaribioside carbohydrate antibodies AMCA : anti-mannobioside carbohydrate antibodies ASCA : anti- Saccharomyces cerevisiae antibodies CD : Crohn's disease CRP : C-reactive protein FAP : familial adenomatous polyposis GP2 : glycoprotein 2 IBD : inflammatory bowel diseases IPAA : ileal pouch anal anastomosis PAB : pancreatic (auto)-antibody PDAI : pouchitis disease activity index UC : ulcerative colitis