RESEARCH ARTICLE Preclinical Studies Identify Non-Apoptotic Low-Level Caspase-3 as Therapeutic Target in

The majority of pemphigus vulgaris (PV) patients suffer from a live-threatening loss of inter-cellular adhesion between keratinocytes (acantholysis). The disease is caused by auto-antibodies that bind to desmosomal cadherins desmoglein (Dsg) 3 or Dsg3 and Dsg1 in mu-cous membranes and skin. A currently unresolved controversy in PV is whether apoptosis is involved in the pathogenic process. The objective of this study was to perform preclinical studies to investigate apoptotic pathway activation in PV pathogenesis with the goal to as-sess its potential for clinical therapy. For this purpose, we investigated mouse and human skin keratinocyte cultures treated with PV antibodies (the experimental Dsg3 monospecific antibody AK23 or PV patients IgG), PV mouse models (passive transfer of AK23 or PVIgG into adult and neonatal mice) as well as PV patients ’ biopsies (n=6). A combination of TUNEL assay, analyses of membrane integrity, early apoptotic markers such as cleaved poly-ADP-ribose polymerase (PARP) and the collapse of actin cytoskeleton failed to pro-vide evidence for apoptosis in PV pathogenesis. However, the in vitro and in vivo PV mod-els, allowing to monitor progression of lesion formation, revealed an early, transient an