049 Development of active mouse models to recapitulate pemphigus subtypes and to evaluate response to therapy

Abstract

Pemphigus is an autoimmune bullous disease characterized by loss of adhesion caused by autoantibodies (PVIgG) against keratinocyte antigens, desmogleins (Dsg1 and Dsg3) and non-Dsg proteins, such as acetylcholine receptors (AChR) or Desmocollin (Dsc3). Different PVIgG result in diverse clinical phenotypes. In order to recapitulate the features of human pemphigus, to evaluate the role of different antigens, and to test the response to therapy, we generated an active mouse model. We produced murine recombinant proteins (rDsg1, rDsg3, rDsc3, rAChRM3, rAChRNα7 and rAChRNα9). We then immunized Dsg3-/- mice with mouse rDsg3, and adoptively transferred their splenocytes into C57BL/6 Rag2-/- (Rag2) immunodeficient mice, that express Dsg3. Recipient mice stably produce the pathogenic anti-Dsg3 IgG and exhibit the features of pemphigus vulgaris, as shown by clinical score and Dsg3 levels (ELISA). We also generated the pemphigus foliaceous active mouse model, by breaking the immunological tolerance in WT mice with rDsg1. Similarly, we created a Dsg1/Dsg3 mouse model by transferring the combined splenocytes from mice immunized with rDsg1 and mice immunized with rDsg3 into Rag2 mice. The Dsg1/Dsg3 mouse model displays the most severe phenotype, reproduces symptoms of mucocutaneous PV in patients, as well as the same level of intraepithelial detachment and inter-keratinocyte deposits of IgG. Moreover, only the Dsg1/Dsg3 mice significantly responded to treatment with methylprednisolone in a time-dependent manner (clinical score and ELISA). In conclusion, we created new tools that could 1. improve the knowledge on pemphigus pathomechanisms; 2. serve for the identification of new therapeutic targets; 3. allow a long-term pre-clinical observation with or without current and novel therapies