Autoimmunity to Type VII Collagen: Epidermolysis Bullosa Acquisita

Abstract

Epidermolysis bullosa acquisita (EBA) is an acquired, mechanobullous disease characterized by autoimmunity to type VII collagen. Type VII collagen makes anchoring fibrils, structures that connect the epidermis and its underlying basement membrane zone to the papillary dermis. EBA patients exhibit skin fragility, blisters, scars and milia formation reminiscent of genetic dystrophic epidermolysis bullosa (DEB). DEB patients have diminutive or absent anchoring fibrils due to a genetic defect in the gene encoding type VII collagen. EBA patients have a decrease in normally functioning anchoring fibrils secondary to an abnormality in their immune system in which they produce 'pathogenic' IgG anti-type VII collagen antibodies. The pathogenicity of these autoantibodies has been demonstrated by passive transfer animal models, in which anti-type VII collagen antibodies injected into a mouse produced an EBA-like blistering disease in the animal. EBA has several distinct clinical presentations. It can present with features similar to DEB, bullous pemphigoid, cicatricial pemphigoid, Brunsting-Perry pemphigoid or IgA bullous dermatosis. Treatment for EBA is unsatisfactory, however, some therapeutic success has been reported with colchicine, dapsone, photophoresis, infliximab and intravenous immunoglobulin.