Antigen-Fc fusion therapy reduces severity of a model of pemphigus vulgaris without systemic immunosuppression

Pemphigus vulgaris is a B cell-mediated autoimmune disease characterized by autoantibodies targeting desmoglein-3 (Dsg3), a critical adhesion molecule in epithelial tissues. Current treatments rely on broad immunosuppression, highlighting the need for more targeted therapeutic approaches in pemphigus vulgaris and other autoantibody-driven disorders. We engineered a therapeutic fusion protein consisting of the pathogenic domains of Dsg3 linked to either human immunoglobulin G1 (IgG1) or mouse IgG2a (Dsg3-Fc). In vitro, Dsg3-Fc selectively eliminated Dsg3-autoreactive B cells. In vivo, Dsg3-Fc effectively depleted human B cells expressing patient-derived anti-Dsg3 B cell receptors, even in the presence of circulating autoantibodies. Moreover, Dsg3-Fc inhibited both disease initiation and progression in a polyclonal, active pemphigus vulgaris model in immunocompetent mice. In addition, Dsg3-Fc rapidly neutralized pathogenic autoantibodies without inducing systemic toxicity. These findings demonstrate that targeting pathogenic B cells and neutralizing autoantibodies through autoantigen-Fc fusion proteins may represent a promising therapeutic strategy for pemphigus vulgaris and potentially other autoantibody-mediated diseases without the need for global immunosuppression.