6th Annual BMRP Investigator Meeting - Abstract
Identification of Target Antigens of Antibodies in Inflammatory Bowel Disease: Protein Microarray Experiments identify Phla1 as a Target Antigen
Nathalie Vermeulen1,b, Severine Vermeire1, Paul Rutgeerts1, Xavier Bossuyt2,a
1Departments of Gastroenterology and 2 Laboratory Medicine, University Hospital Gasthuisberg (Leuven, Belgium)
Patients with inflammatory bowel disease display several antibodies which are directed to a variety of antigens, such as food antigens, bacterial antigens and self-antigens. These antibodies may serve as serological markers for diagnosis, classification, characterization and prognosis. We aimed to identify target antigens of autoantibodies in IBD. For this purpose, the innovative approach of protein microarray was used. Sera from 10 ulcerative colitis patients (UC), 15 Crohn’s disease patients (CD) and 5 healthy controls (HC) were probed against slides spotted with a large number of human proteins. This allowed identification of target antigens of antibodies present in the sera of patients. The protein microarray experiments revealed 75 proteins to which IBD patients had a significantly higher reactivity than healthy controls and 88 proteins to which healthy subjects had a higher reactivity than IBD patients. One of the identified autoantigens in IBD was Pleckstrin homology-like domain, family A, member 1 (Phla1). Phla1 is described as a pro-apoptotic protein involved in cell death mechanisms in different cell types. The protein microarray revealed antibodies against Phla1 in 5 of 10 (50.0%) UC and in 9 of 15 (60.0%) CD patients, compared to 0 of 5 controls. In the validation experiment on a second cohort, 27 of 63 (42.8%) UC patients and 33 of 66 (50.0%) CD patients had anti-Phla1 antibodies, in contrast to 19 of 66 (28.7%) healthy controls and 22 of 66 (33.3%) non-IBD gastrointestinal controls. (p<0.05; IBD vs. controls) Our data confirm the protein microarray as a novel technology to identify antibodies. Using this technology, we showed that Phla1 is an autoantigen in IBD. Independent cohorts are needed to confirm these first results.