Anti–α-enolase Antibodies in Patients with Inflammatory Bowel Disease

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Abstract
Background: Patients with inflammatory bowel disease (IBD) carry autoantibodies such as perinuclear antineutrophil cytoplasmic antibodies (pANCA). α-Enolase has been proposed as a target antigen in IBD. We evaluated the prevalence and diagnostic value of anti–α-enolase antibodies in IBD and related disorders. Methods: We used a classic proteomic approach with extracts from granulocytes and pANCA-positive ulcerative colitis (UC) sera to confirm α-enolase as a target antigen. By means of Western blot analysis, we screened a cohort of 525 subjects for the presence of anti–α-enolase antibodies. We performed GeneArray experiments on RNA extracted from colonic mucosal biopsies from 35 IBD and 6 control patients. Results: We detected anti–α-enolase antibodies 49.0% of patients with UC, 50.0% of patients with Crohn’s disease, 30.5% of patients with primary sclerosing cholangitis, 37.8% of patients with autoimmune hepatitis, 34.0% of patients with ANCA-positive vasculitis, 31.0% of non-IBD gastrointestinal controls, and 8.5% of healthy controls. Gene array experiments showed a significant upregulation of α-enolase mRNA in colonic mucosal biopsies from patients with IBD, but not from controls. There was no association between the presence of pANCA and anti–α-enolase antibodies. Preabsorption with α-enolase did not eliminate the pANCA pattern on indirect immunofluorescence. Conclusions: Anti–α-enolase antibodies are present in a substantial proportion of patients with IBD, patients with various inflammatory/autoimmune disorders, and non-IBD gastrointestinal controls. Therefore, anti–α-enolase antibodies are of limited diagnostic value for the diagnosis of IBD.