Pemphigus vulgaris (PV) is an autoimmune blistering disease caused by autoantibodies mainly directed against desmoglein (Dsg) 3. So far, only broad systemic immunosuppression and B-cell depletion are being applied in PV patients. In this study, we aim at investigating a Dsg3-specific CD4+ T cell directed therapy in PV. We apply human leukocyte antigen (HLA)-transgenic mice transgenic for the PV-associated HLA-DRB1*04:02-DQ8 haplotype, the human CD4 coreceptor and lack mouse MHC class II (I-Aß-/-). Immunization with recombinant human Dsg3 protein leads to induction of Dsg3-specific CD4+ T and Dsg3-reactive IgG producing B cells. For characterization of low-frequent Dsg3-specific CD4+ T cells in lymphatic tissues we use DRB1*04:02 HLA class II Dextramers loaded with immunodominant Dsg3-T cell epitopes. CD4+ T cells are primarily detected after initial immunization (4% Dsg3+ CD4+ CD19+ cells) and their number is steadily decreasing thereafter. For analysis of Dsg3-specific B-cells we used fluorochrome-labelled Dsg3. B cell subpopulations occur transiently in spleen shortly after Dsg3-immunization (day 6) and cannot be detected at day 21 anymore. However, at day 21 Dsg3-specific plasma cells can be identified in bone marrow shown by Dsg3-specific B-cell ELISPOT analysis. For induction of Dsg3-specific T cell tolerance, we applied a set of immunodominant Dsg3 CD4+ T cell epitopes linked to nanoparticles in a preventive setting prior to i.p. immunization with human Dsg3. Anti-Dsg3 antibody formation was reduced by 74% and 80%, respectively, compared to control animals. To summarize, we are able to detect antigen specific T and B cells upon Dsg3-immunization, and can efficiently promote a CD4+ T-cell specific tolerance induction based on the application of peptide-bound nanoparticles in a preclinical mouse model of PV. These preclinical proof of concept results hold great promise to translate the concept of Dsg3-specific T cell tolerance induction into the clinic.

Development of a mouse model of Pemphigus Vulgaris as a tool to evaluate nanoparticle induced antigen-specific tolerance