Non-pathogenic pemphigus foliaceus (PF) IgG acts synergistically with a directly pathogenic PF IgG to increase blistering by p38MAPK-dependent desmoglein 1 clustering

Abstract

Background-Pemphigus foliaceus (PF) is an autoimmune blistering disease caused by autoantibodies (Abs) against desmoglein 1 (Dsg1). PF sera contain polyclonal Abs which are heterogeneous mixture of both pathogenic and non-pathogenic Abs, as shown by isolation of monoclonal Abs (mAbs).Objective-To investigate how pathogenic and non-pathogenic anti-Dsg1 Abs contribute to blister formation in PF.Methods-Using organ-cultured human skin, we compared the effect of a single pathogenic antiDsg1 IgG mAb, a single non-pathogenic anti-Dsg1 IgG mAb, and their mixture on blister formation as analyzed by histology, subcellular localization of IgG deposits and desmosomal proteins by confocal microscopy, and desmosomal structure by electron microscopy. In addition, we measured keratinocyte adhesion by an in vitro dissociation assay.Results-24 h after injection, a single pathogenic anti-Dsg1 IgG caused a subcorneal blister with IgG and Dsg1 localized linearly on the cell surface of keratinocytes. A single non-pathogenic antiDsg1 IgG bound linearly on the keratinocytes but did not induce blisters. A pathogenic and a nonpathogenic IgG mAb injected together caused an aberrant granular pattern of IgG and Dsg1 in the lower epidermis with blister formation in the superficial epidermis. Electron microscopy demonstrated that the mixture of mAbs shortened desmosomal lengths more than a single mAb in the basal and spinous layers. Furthermore, although Dsg1 clustering required both cross-linking of Dsg1 molecules by the non-pathogenic IgG plus a pathogenic antibody, the latter could be in the form of a monovalent single chain variable fragment, suggesting that loss of trans-interaction of ✩ This work was done at Tokyo, Japan. *Corresponding author at: Department of Dermatology, Toho University School of Medicine, 6-11-1, Omori-Nishi, Ota-ku, Tokyo 143-8541, Japan. ken.ishii@med.toho-u.ac.jp (K. Ishii). Conflict of interestThe authors have no conflict of interest to declare. HHS Public AccessAuthor manuscript J Dermatol Sci. Author manuscript; available in PMC 2017 July 14. Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptDsg1 is required for clustering. Finally, a p38MAPK inhibitor blocked Dsg1 clustering. When pathogenic strength was measured by the dissociation assay, a mixture of pathogenic and nonpathogenic IgG mAbs disrupted keratinocyte adhesion more than a single pathogenic mAb. This pathogenic effect was only partially suppressed by the p38MAPK inhibitor.Conclusion-These findings indicate that a polyclonal mixture of anti-Dsg1 IgG antibodies enhances pathogenic activity for blister formation associated with p38MAPK-dependent Dsg1 clustering and that not only pathogenic antibodies but also non-pathogenic antibodies coordinately contribute to blister formation in PF.

Mechanisms Causing Loss of Keratinocyte Cohesion in Pemphigus

“…Antibodies selectively targeting Dsg1 and Dsg3 are sufficient to cause acantholysis and skin vesiculation in mice and in ex vivo human skin (Di Zenzo et al, 2012;Eming et al, 2014;Ishii et al, 2008;Langenhan et al, 2014;Payne et al, 2005;Saito et al, 2012;Spindler et al, 2013;Yamagami et al, 2010;Yeh et al, 2006). PV-IgG have been shown to induce direct inhibition of Dsg3 binding, and several signaling pathways downstream of antibody binding including p38 mitogen-activated protein kinase, Ca 2þ , protein kinase C, Src, EGFR, RhoA, c-Myc, glycogen synthase kinase 3, Pg, and caspases were shown to be involved in the loss of keratinocyte cohesion in PV, pemphigus foliaceus, and atypical pemphigus (Bektas et al, 2013;Berkowitz et al, 2006Berkowitz et al, , 2008Caldelari et al, 2001;Chernyavsky et al, 2007;Cirillo et al, 2010Cirillo et al, , 2014Dehner et al, 2014;Frusic-Zlotkin et al, 2006;Li et al, 2009;Luyet et al, 2015;Mao et al, 2011Mao et al, , 2014Saito et al, 2012;Sánchez-Carpintero et al, 2004;Sayar et al, 2014;Spindler et al, 2011Waschke et al, 2006;Williamson et al, 2006;Yoshida et al, 2017).…”

High Expression of Collagen XVII Compensates for its Depletion Induced by Pemphigoid IgG in the Oral Mucosa

“…However, for the combination of IgG against the NC16A domain and the C-terminus, COL17 depletion was significantly enhanced ( Figure 5). The enhancement of the pathogenicity by nonpathogenic IgG has been reported in pemphigus vulgaris (Kawasaki et al, 2006) and pemphigus foliaceus (Yoshida et al, 2017). The depletion activity of pathogenic mAbs against Dsg3 is known to be boosted when those mAbs act in combination with nonpathogenic mAbs (Yamamoto et al, 2007).…”

From bench to bedside: evolving therapeutic targets in autoimmune blistering disease

“…In a passive transfer mouse model, p38MAPK inhibition impedes blistering by PV IgG . In an ex vivo human organ culture model utilizing human skin, IgG induced p38MAPK phosphorylation and downstream desmoglein clustering, but was not essential for blistering . Mao et al .…”

“…97 In an ex vivo human organ culture model utilizing human skin, IgG induced p38MAPK phosphorylation and downstream desmoglein clustering, but was not essential for blistering. 98 Mao et al 99 further demonstrated that mice with p38 deletion continue to develop suprabasilar blisters in the presence of PV IgG, suggesting that p38MAPK activation may be secondary to the loss of intercellular adhesion and not the root cause.…”