Pancreatic Autoantibodies Against CUZD1 and GP2 Are Associated with Distinct Clinical Phenotypes of Crohn's Disease

Background: Inflammatory bowel disease (IBD) is characterized by a broad spectrum of clinical phenotypes with different outcomes. In the last decades, several IBD-associated autoantibodies have been identified and investigated for their diagnostic relevance. Autoantibodies against the pancreatic glycoproteins (PAB) CUB and zona pellucida-like domains-containing protein 1 (CUZD1), and glycoprotein 2 (GP2) have been demonstrated to possess high specificity for the diagnosis of IBD. Although several studies have shown significant interrelations of anti-GP2 positivity with disease phenotype, associations of clinical phenotypes with anti-CUZD1 are still unknown. The aim was to identify the association of clinical phenotypes with anti-CUZD1 and anti-GP2 in a well-defined German IBD cohort. Methods: Patients with IBD (224 patients with Crohn's disease and 136 patients with ulcerative colitis), who were tested for anti-GP2 and anti-CUZD1 immunoglobulin G and immunoglobulin A by indirect immunofluorescence on transfected cells between 2005 and 2013, were included. Serotype and specified phenotypic data were collected in retrospect and statistically analyzed. Results: Both anti-GP2 (P < 0.001) and anti-CUZD1 (P < 0.001) were significantly more prevalent in patients with Crohn's disease than in ulcerative colitis. PAB positivity was associated with ileocolonic disease (P 0.002), perianal disease (P 0.011), immunosuppressive treatment (P 0.036), and ASCA positivity (P 0.036). Anti-CUZD1 positivity was associated with ileocolonic (P 0.016) and perianal disease (P 0.002), whereas anti-GP2 positivity was positively associated with stricturing behavior (P 0.016). Conclusions: We found distinct clinical phenotypes to be associated with PAB positivity. Therefore, determination of PABs and their subgroup analysis might identify patients with complicated disease behavior. However, the clinical relevance of our findings should be further evaluated in prospective cohorts.