Induction of Epidermolysis Bullosa Acquisita in Mice by Passive Transfer of Autoantibodies from Patients

Abstract

Epidermolysis bullosa acquisita (EBA) is an autoimmune sub-epidermal blistering disease characterized by autoantibodies to type VII (anchoring fibril) collagen. To date, however, direct evidence for a pathogenic role of human EBA autoantibodies has not been demonstrated. In this study, we affinity-purified anti-type VII collagen antibodies from EBA patients' sera and then injected them into adult hairless immunocompetent mice. Mice injected with EBA autoantibodies developed skin fragility, blisters, erosions, and nail loss on their paws - all features of EBA patients. By clinical, histological, immunological, and ultrastructural parameters, the induced lesions were reminiscent of human EBA. Histology showed bullous lesions with an epidermal-dermal separation. IgG and C3 deposits were observed at the epidermal-dermal junction. All mice had serum antibodies that labeled the dermal side of salt-split human skin like EBA sera. Direct immunogold electron microscopy specifically localized deposits of human IgG to anchoring fibrils. (Fab')(2) fragments generated from EBA autoantibodies did not induce disease. We conclude that EBA human patient autoantibodies cause sub-epidermal blisters and induce EBA skin lesions in mice. These passive transfer studies demonstrate that human EBA autoantibodies are pathogenic. This novel EBA mouse model can be used to further investigate EBA autoimmunity and to develop possible therapies.

The Cartilage Matrix Protein Subdomain of Type VII Collagen Is Pathogenic for Epidermolysis Bullosa Acquisita

“…The animals developed a subepidermal bullous disease with clinical, histological, immunological, and ultrastructural features similar to human EBA. 23 These results provide evidence that human EBA autoantibodies to the NC1 domain of type VII collagen are pathogenic and capable of inducing epidermal-dermal separation of skin.…”

“…In previous studies with the passive transfer EBA animal models, we and others 22,23 have shown that complement fixation likely plays a role in the pathogenesis of the murine EBA model. In the present study, we also showed that affinity-purified anti-CMP EBA IgG, but not flowthrough IgG (depleted of CMP reactivity), fixed murine C3 complement and recruited neutrophils when injected into mice.…”

“…23 To determine whether pathogenic EBA autoantibodies are reactive with CMP epitopes, we affinity-purified CMP-specific EBA antibodies and analyzed these antibodies by immunoblotting and immunofluorescence. Using a panel of GST fusion proteins encompassing the complete NC1 domain of type VII collagen ( Figure 4A), 18 we found that the pathogenic EBA IgG used in this study recognized exclusively only CMP ( Figure 4B, lane 2).…”

“…23 Undigested IgG and Fc fragments were removed by affinity chromatography using a protein G-Sepharose Fast Flow column (Amersham Biosciences). Purified F(abЈ) 2 fragments migrated as a 100-kd band under nonreduced SDS-PAGE.…”

GM-CSF Modulates Autoantibody Production and Skin Blistering in Experimental Epidermolysis Bullosa Acquisita

“…We selected epidermolysis bullosa acquisita (EBA) as a model, because the pathogenic relevance of autoantibodies in this disease has been clearly demonstrated (23)(24)(25), and induction of EBA has been described in a patient treated with GM-CSF (26). These autoantibodies are directed to type VII collagen (COL7), a major component of the hemidesmosomal adhesion complex of the dermal-epidermal junction (DEJ) (27,28).…”