Identification of new biomarkers for the diagnosis of Bechterew's disease

Abstract

Ankylosing spondylitis (AS), or Bechterew's disease, is a chronic inflammatory rheumatic disorder primarily affecting the spine and sacroiliac joints. Specific serological tests and pathognomonic clinical features are missing, delaying the diagnosis of AS. Although the humoral immune response is not a hallmark of the disease, emerging evidence suggests a role in the etiology of AS. Therefore, we aim to identify novel antibody (Ab) biomarkers for the diagnosis of AS. Previously, a constructed human rheumatoid arthritis (RA) cDNA phage display library was screened for Ab reactivity in pooled plasma of early AS patients and age and gender matched healthy controls (HC) by serological antigen selection. Using phage ELISA, resulting Ab targets were characterized for Ab reactivity in pooled and individual plasma samples of AS patients and HC. We detected the presence of Ab in AS patients, indicating the humoral immune response to be involved. Screening of the RA display library resulted in 67 different Ab targets. Using phage ELISA, screening of Ab reactivity against these Ab targets demonstrated 21 targets with a heterogeneous reactivity in early AS patients and not in HC.

Our results indicate the presence of Ab reactivity in AS patients, suggesting the involvement of the humoral immune response. The 21 antigen targets will be further validated in a bigger screening using more AS patients, other rheumatic patients and HCs. In conclusion, the 21 targets have the potential as novel biomarkers for the improved diagnosis of AS.