Recessive Dystrophic epidermolysis bullosa (RDEB) is a skin genetic disease caused by mutations in COL7A1 (coding type VII collagen). Type VII collagen is essential to maintain the fully functional dermal-epidermal junction, and the loss of type VII collagen results in detachment of epidermis. RDEB patients, without functional type VII collagen, suffer from the repetitive blistering and have high risk of early-onset aggressive squamous cell carcinoma. Currently, no fundamental treatment is available for RDEB. In this study, we aimed to develop therapeutics for RDEB using HMGB1 peptide, which we have previously identified as an endogenous SOS signal that can activates bone marrow stem/progenitor cells. Systemic injection of HMGB1 peptide in DEB model mice ameliorated mitten deformity and stenosis, and significantly extended the survival. This HMGB1 peptide treatment model provides a unique opportunity to investigate on how the DEB skin can be reconstructed. Thus, we comprehensively characterized the transcriptome (by RNA-seq) and epigenome (by ATAC-seq) of the skin from the HMGB1 peptide treated DEB model mice with single-cell resolution. Decrease in the number of immune cells upon the HMGB1 treatment was identified by both single cell RNA- and ATAC-seq analyses, indicating the treatment suppressed the inflammation. Furthermore, single cell ATAC-seq analysis depicted a sign of massive reprogramming in the transcription factor usage of the basal layer keratinocytes (contain stem/progenitor cells) in the HMGB1 peptide treated DEB model mice. These singe-cell level analyses suggested that the HMGB1 peptide can induce skin reconstruction by reprogramming the transcriptional program of skin stem/progenitor cells, and assured that the HMGB1 peptide serves as a promising option for the RDEB treatment.

Single cell transcriptome and epigenome analyses in a murine model of dystrophic epidermolysis bullosa