Peptide-mediated desmoglein 3 crosslinking prevents pemphigus vulgaris autoantibody-induced skin blistering

Abstract

In pemphigus vulgaris, a life-threatening autoimmune skin disease, epidermal blisters are caused by autoantibodies primarily targeting desmosomal cadherins desmoglein 3 (DSG3) and DSG1, leading to loss of keratinocyte cohesion. Due to limited insights into disease pathogenesis, current therapy relies primarily on nonspecific long-term immunosuppression. Both direct inhibition of DSG transinteraction and altered intracellular signaling by p38 MAPK likely contribute to the loss of cell adhesion. Here, we applied a tandem peptide (TP) consisting of 2 connected peptide sequences targeting the DSG adhesive interface that was capable of blocking autoantibody-mediated direct interference of DSG3 transinteraction, as revealed by atomic force microscopy and optical trapping. Importantly, TP abrogated autoantibody-mediated skin blistering in mice and was effective when applied topically. Mechanistically, TP inhibited both autoantibody-induced p38 MAPK activation and its association with DSG3, abrogated p38 MAPK-induced keratin filament retraction, and promoted desmosomal DSG3 oligomerization. These data indicate that p38 MAPK links autoantibody-mediated inhibition of DSG3 binding to skin blistering. By limiting loss of DSG3 transinteraction, p38 MAPK activation, and keratin filament retraction, which are hallmarks of pemphigus pathogenesis, TP may serve as a promising treatment option.

Desmoglein 2 Compensates for Desmoglein 3 but Does Not Control Cell Adhesion via Regulation of p38 Mitogen-activated Protein Kinase in Keratinocytes

“…In line with previous data using AK23 to inhibit binding of Dsg3 (20), Dsg3 depletion induced loss of cell adhesion, p38 MAPK activation, and cytokeratin retraction. In contrast, Dsg2 depletion yielded none of these results and seemed relevant under conditions of simultaneous loss of Dsg3 function only.…”

“…ImageJ was also used for the quantification of fluorescence intensity of the indicated proteins on the cell membrane and for measuring the extent of cytokeratin retraction of immunofluorescence experiments. The distance between the aggregation of intermediate filaments of opposing cells was measured essentially as described previously (20)…”

“…Moreover, we detected that Dsg3 forms a complex with p38 MAPK (20). In this study, we investigated the relevance of both desmogleins for intracellular signaling involved in cell cohesion, specifically p38 MAPK.…”

“…Recently, we described an adhesion-dependent signaling complex consisting of Dsg3 and activated, e.g. phosphorylated, p38 MAPK (p-p38 MAPK), which established a link between p38 MAPK activation and loss of Dsg3 interaction in pemphigus vulgaris (20). Furthermore, Dsg3, via interaction with E-cadherin, has been demonstrated to be involved in Src signaling (3,21).…”

150thAnniversary Series: Desmosomes and Autoimmune Disease, Perspective of Dynamic Desmosome Remodeling and Its Impairments in Pemphigus

“…It should be noted that Dsg3 is phosphorylated transiently before its degradation . PV-IgG-activated signaling molecules found after these fi ndings include EGFR (Bektas et al, 2013;Chernyavsky et al, 2007), Src (Chernyavsky et al, 2007;Cirillo et al, 2014), p38 MAPK (Chernyavsky et al, 2007;Jolly et al, 2010;Spindler et al, 2013), RhoA (Waschke et al, 2006), c-myc (Williamson et al, 2006), PERP (Nguyen et al, 2009), FAK (Gil et al, 2012), Akt/ mTOR (Pretel et al, 2009) and cdk2 (Lanza et al, 2008). Especially, it is worthwhile to note that an anti-Dsg3 antibody, AK23, activates EGFR followed by an increase in Myc levels, events leading keratinocytes to proliferate in association with Dsg3 depletion and acantholysis in AK23-injected mice (Schulze et a., 2012).…”