Pemphigus foliaceus IgG causes dissociation of desmoglein 1–containing junctions without blocking desmoglein 1 transinteraction
Jens Waschke, Paola Bruggeman, Werner Baumgartner, Detlef Zillikens, Detlev Drenckhahn
Jens Waschke, Paola Bruggeman, Werner Baumgartner, Detlef Zillikens, Detlev Drenckhahn
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Research Article Dermatology

Pemphigus foliaceus IgG causes dissociation of desmoglein 1–containing junctions without blocking desmoglein 1 transinteraction

Abstract

Autoantibodies against the epidermal desmosomal cadherins desmoglein 1 (Dsg1) and Dsg3 have been shown to cause severe to lethal skin blistering clinically defined as pemphigus foliaceus (PF) and pemphigus vulgaris (PV). It is unknown whether antibody-induced dissociation of keratinocytes is caused by direct inhibition of Dsg1 transinteraction or by secondary cellular responses. Here we show in an in vitro system that IgGs purified from PF patient sera caused cellular dissociation of cultured human keratinocytes as well as significant release of Dsg1-coated microbeads attached to Dsg-containing sites on the keratinocyte cellular surface. However, cell dissociation and bead release induced by PF-IgGs was not caused by direct steric hindrance of Dsg1 transinteraction, as demonstrated by single molecule atomic force measurements and by laser trapping of surface-bound Dsg1-coated microbeads. Rather, our experiments strongly indicate that PF-IgG–mediated dissociation events must involve autoantibody-triggered cellular signaling pathways, resulting in destabilization of Dsg1-based adhesive sites and desmosomes.

Authors

Jens Waschke, Paola Bruggeman, Werner Baumgartner, Detlef Zillikens, Detlev Drenckhahn

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Effect of PF-IgGs on binding of Dsg1-coated beads to HaCaT cells. Beads ...
Effect of PF-IgGs on binding of Dsg1-coated beads to HaCaT cells. Beads were allowed to settle on the surface of HaCaT cells for 30 minutes (control). Number of bound beads was reduced by simultaneous incubation of EGTA (5 mM, 30 minutes). Incubation of monolayers with attached beads for an additional 30 minutes with IgG fractions from 2 patients (PF1- and PF2-IgG, 35 μg/ml each) as well as with a monoclonal antibody (1:50) directed against the extracellular domain of human Dsg1 significantly reduced the number of bound beads (label in white box and white bars). Immunoabsorption using Dsg1-coated beads but not control absorption using VE-cadherin–labeled beads completely abolished the effect of PF-IgGs on bead adhesion. Preincubation of HaCaT cells with PF-IgGs prior to bead settlement also reduced bead binding (label in gray box and gray bars) whereas preincubation of beads with PF-IgGs did not inhibit bead binding. In contrast, the monoclonal Dsg1 antibody reduced bead binding also when applied for preincubation with beads, indicating a different mechanism underlying the reduction of Dsg1 adhesion (n = 6 for each condition).