Single-cell RNA-seq reveals fibroblast heterogeneity and increased mesenchymal fibroblasts in human skin fibrotic diseases (RNA-seq)

Skin fibrotic disease representsa major global healthcare burden, characterized by fibroblast hyperproliferation and excessive accumulation of extracellular matrix.Fibroblasts are found to be heterogeneous in multiple fibrotic diseases,but the fibroblast heterogeneity of skin fibrotic diseases remains unknown.In this study, we performed single-cell RNA-seq in keloid, a paradigm of skin fibrotic diseases, andnormal scardermis tissues.Our results indicate thatkeloid and normal scar fibroblasts could be divided into 4 subpopulations: secretory-papillary, secretory-reticular, mesenchymal and pro-inflammatory.The percentage of mesenchymal fibroblast subpopulationincreased significantly in keloid compared to normal scar. Interestingly, we also found increasing mesenchymal fibroblast subpopulation in scleroderma, another skin fibrotic disease.Function studies showed that the mesenchymal fibroblasts promoted collagen synthesis of the other fibroblasts in keloid partiallythrough secreting POSTN. These findings will help us understandskin fibroticpathogenesis in depth,and provided potential target cells for fibrotic diseases therapies. Overall design: We just used dermis for scRNA-seq analysis because keloid represents a skin dermis fibrosis disease. After stringent quality control, we obtained transcriptomes of 40655 cells (Keloid(nsample=3): 21488; Normal scar(nsample=3):19167). For RNA-seq, We flow sorted keloid fibroblasts that were CD90+ and CD266+/CD9- or CD90+ other cells (other fibroblasts),performed RNA-seq to compare the gene expression of CD266+/CD9- fibroblasts and other fibroblasts.