Molecular therapies for junctional epidermolysis bullosa

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Junctional epidermolysis bullosa (JEB) caused by type XVII collagen (C17) gene (COL17A1) mutations manifests with skin blistering and chronic wounds. The treatment consists of wound management and there is a high-unmet therapeutic need. Animal models are early lethal or do not reproduce the human disease situation. This proposal, based on extensive preliminary work and on the complementary expertise of the applicants, aims at developing molecular therapies to restore the missing C17, thus providing the basis for clinical trials. To target different types of pathogenic variants in a personalized manner, we will develop read-through therapy for COL17A1 nonsense mutations (20% of the COL17A1 mutations) and protein therapy for all other COL17A1 mutations. Translational read-through inducing drugs (TRIDs) with different mechanisms of action, as well as enhancers and a nonsense mediated decay inhibitor, will be tested on cells derived from patients to find the optimal concentrations and combinations for each COL17A1 nonsense mutation. Furthermore, we will test the hypothesis that the extracellular shed C17 ectodomain (with and without the highly antigenic NC16A domain) is able to be integrated in the basement membrane during wound healing and to promote wound closure. TRIDs and recombinant C17 ectodomain will be also applied together in two-and three dimensional cell models. The primary read-outs will be the level of restored C17, the viability of the cells, the stabilization of the dermal-epidermal junction and the effect on wound closure in reconstructed skin models. As secondary read-outs, we will investigate C17 turnover, and its effect on epidermal architecture and signaling pathways. For assessment, we will employ biochemical, cell biological and tissue morphological assays. Finally, this project will identify combinations of drugs that might be effective in other genetic disorders, and will establish a reproducible workflow to investigate the precise effect of molecular therapies on individual mutations in epidermolysis bullosa.