Autoantibody signatures in children with celiac disease, juvenile idiopathic arthritis, and polyautoimmunity

Objective To determine if multiplex autoantibody arrays can identify novel biomarker signatures in children with one or multiple autoimmune diseases (polyautoimmunity). Methods Plasma collected from children (18 years or younger) in the Boston Children's Hospital Precision Link Biobank for Health Discovery between January 2007 and June 2021 was analyzed using a microarray with 120 autoantigens associated with various autoimmune diseases to assess for both immunoglobulin G (IgG) and A (IgA) autoantibodies. To determine if disease‐specific, we binary classified those with polyautoimmunity and the most common autoimmune diseases in our cohort (autoimmune thyroid disease, type 1 diabetes, or celiac disease [CeD]). For each comparison within and between groups, the autoantibody intensity was releveled to the control and a linear model was fit. Results Plasma was analyzed from 114 children with either CeD ( n = 31), juvenile idiopathic arthritis ( n = 20), polyautoimmunity ( n = 31), or no autoimmune disease ( n = 32). Overall, children with polyautoimmunity had higher levels of specific autoantibodies relative to the other groups. Children with CeD and polyautoimmunity expressed higher levels of H/K ATPase IgA and IgG and MDA5 IgG compared to those with CeD alone. Conclusions Use of multiplex antigen arrays in patients with and without polyautoimmunity is a valuable tool to identify known and potentially novel disease‐antigens. Further study is needed to determine the role of H/K ATPase autoantibodies in monitoring of CeD patients.