Overlap of Characteristic Serological Antibodies in Rheumatoid Arthritis and Wheat-Related Disorders

BACKGROUND AND AIMS: Rheumatoid arthritis (RA) and celiac disease (CD) are members of the autoimmune disease family while they have been shown to share multiple aspects in epidemiology and clinical manifestations. The aim of this study was to assess the presence of wheat protein antibodies in RA seropositive subjects and the presence of RA diagnostic markers in subjects with seropositive wheat-related disorders including CD. METHODS: Serum samples were collected from 844 subjects with joint pain and/or gastrointestinal symptoms and tested by a CD panel (anti-tTG and anti-DGP), a Wheat Zoomer (WZ) antibody panel (IgG/IgA to 14 wheat proteins), and a RA panel (anti-CCP and anti-RF). Retrospective analysis was completed using de-identified clinical data and test results. RESULTS: The prevalence of RA markers was first investigated in CD- or WZ-positive subjects and negative controls. 49 subjects were seropositive in the CD panel with 10 (20%) RA positivity. 605 subjects were seropositive in the WZ panel with 106 (18%) RA positivity. 222 subjects were seronegative in either panels with 12 (6%) RA positivity. Next, the frequency of the CD markers and the clinically relevant wheat protein antibodies were investigated in the RA-positive subjects and negative controls. 128 subjects in this cohort were seropositive in the RA panel with 10 (8%) CD positivity and 106 (83%) WZ positivity, compared to 716 RA seronegative controls with 39 (5%) CD positivity and 499 (70%) WZ positivity. CONCLUSIONS: Our data presents an apparent trend of overlapped serological antibody biomarker positivity in RA and wheat-related disorders.