Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo

Abstract

Paraneoplastic pemphigus (PNP) is an autoimmune bullous disease associated with underlying neoplasms and characterized by antibodies against desmoglein 3 (Dsg 3) and plakins. Autoantibodies against desmoglein 3 in sera of patients with PNP have been proven to cause acantholysis in vivo in neonatal mice. As a member of the plakin family, autoantibodies against desmoplakin were detected frequently by immunoprecipitation in the sera of PNP. The recombinant C-terminus of desmoplakin was expressed and purified to adsorb the specific autoantibodies against the C-terminus of desmoplakin. In vitro dispase-dependent keratinocyte dissociation assay and in vivo IgG passive transfer into neonatal mice assay were performed, followed by the electronic microscopy examination and TUNEL assay. We found that anti-C terminus of desmoplakin autoantibodies caused blisters and acantholysis in mice skin at a dose-dependent manner. Moreover, dissociated fragments were observed after incubation with the purified IgG against desmoplakin, compared with normal human IgG (P-value =0.0207). The electronic microscopy examination showed the disconnection of keratin intermediate filaments from desmosomes. Lastly, apoptosis of keratinocytes in the TUNEL assay was all detected in the skins of neonatal mice after injection of the anti-C terminus of desmoplakin autoantibodies. Taken together, the study suggests that autoantibodies against the C-terminus of desmoplakin might be pathogenic in PNP.

T cell autoimmunity and immune regulation to desmoglein 3, a pemphigus autoantigen

“…One study reported that purified anti‐desmoplakin antibody from a patient with PNP induced dissociation of keratinocytes in vitro and caused blisters in vivo when transferred to neonatal mice. A possibility that the contaminated anti‐Dsg3 antibody in the purified antibodies could cause blister formation remains elucidated 65 . And the potential pathogenicity of monoclonal antibodies against plakin family proteins has not yet been investigated.…”

“…A possibility that the contaminated anti‐Dsg3 antibody in the purified antibodies could cause blister formation remains elucidated. 65 And the potential pathogenicity of monoclonal antibodies against plakin family proteins has not yet been investigated. Clinically, it is often observed that severe mucosal lesions persist even after the Dsg3 antibody becomes undetectable due to treatment, suggesting that cell‐mediated immune responses recognized in pathology and humoral immunity are crucial aspects to consider in the pathogenesis of PNP.…”