Discovery of IgG4 Anti-Gliadin Autoantibody as a Potential Biomarker of Psoriasis Using an Autoantigen Array

Purpose: Psoriasis is a complex immunological skin disease. However, whether humoral autoimmunity is involved in the pathogenesis of psoriasis remains unclear. The aim is to determine if there are autoantibodies associated with disease activity of psoriasis. Experimental Design: A novel autoantigen array harboring 75 antigens is developed to discover autoantibodies in the serum of psoriasis patients (N = 12) compared to healthy controls (N = 12). Validation studies are performed in a larger cohort of psoriasis patients (N = 73) and healthy controls (N = 75) together with atopic dermatitis as disease controls (N = 10). Results: The screening results demonstrate that immunoglobulin G4 (IgG4) anti-gliadin autoantibodies are significantly elevated in the serum of psoriasis patients, compared to healthy controls. Receiver operating characteristic (ROC) analysis indicates that IgG4 anti-gliadin autoantibody levels can clearly discriminate psoriasis patients from healthy controls with an AUC of 0.98 (p < 0.001). Also, IgG4 anti-gliadin autoantibody can reflect disease severity with the psoriasis area severity index score in a subpopulation of psoriasis patients. Conclusions and Clinical Relevance: These results suggest that IgG4 anti-gliadin autoantibody may be a disease marker of psoriasis, and it may be useful in clinical diagnostics and disease monitoring of psoriasis. Clinical Relevance: This work represents a relatively comprehensive screening of autoantibodies, that is, IgG4 autoantibodies in psoriasis using an in-house autoantigen array. This novel proteomic platform may be useful in clinical screening of IgG type or IgG4 subtype autoantibodies in psoriasis patients for disease monitoring or drug responses. Particularly, IgG4 anti-gliadin autoantibody, as a new potential disease marker of psoriasis, may be useful in clinical diagnostics or prognostics of related immunological disorders.