Inhibition of p38MAPK signaling prevents epidermal blistering and alterations of desmosome structure induced by pemphigus autoantibodies in human epidermis

Abstract

Background

Pemphigus vulgaris (PV) is a skin blistering disease caused by autoantibodies targeting the desmosomal adhesion proteins desmoglein (Dsg) 3 and 1. The mechanisms underlying pemphigus skin blistering are not fully elucidated but p38MAPK activation is one of the signaling events necessary for full loss of cell cohesion. However, it is unclear whether ultrastructural hallmarks of desmosome morphology as observed in patients' lesions are mediated by p38MAPK signaling.

Objective

In this study, we tested the relevance of p38MAPK for blister formation and the ultrastructural changes induced by PV autoantibodies in human skin.

Methods Human skin samples were injected with IgG fractions of one patient suffering from mucocutaneous PV (mcPV-IgG), one from mucosal-dominant PV (mdPV-IgG) or AK23, a pathogenic monoclonal Dsg3 antibody derived from a pemphigus mouse model. Samples were processed for histological and electron microscopy analyses.

Results

McPV-IgG and AK23 but not mdPV-IgG reduced desmosome size, caused interdesmosomal widening and formation of split desmosomes, and altered keratin filament insertion. In contrast, full epidermal blister formation and lower desmosome number were evident in tissue samples exposed to mcPV-IgG only. Pharmacologic inhibition of p38MAPK blunted the reduction of desmosome number and size, ameliorated interdesmosomal widening and loss of keratin insertion and prevented mcPV-IgG-induced blister formation.

Conclusion

Our data demonstrate that blistering can be prevented by inhibition of p38MAPK in human epidermis. Moreover, typical morphologic alterations induced by mcPV-IgG such as interdesmosomal widening and the reduction of desmosome size at least in part require p38MAPK signaling.

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