Single-cell transcriptomic analysis identifies infiltrating plasmacytoid dendritic cells in psoriasis epidermis

The study focuses on the cellular composition of the psoriasis epidermis, using single-cell transcriptomics to identify cell subsets and their interactions in both healthy and psoriatic skin. The research uncovers three keratinocyte populations and seven immune cell subsets exclusive to psoriatic lesions. A significant finding is the identification of a previously undetected population of plasmacytoid dendritic cells (pDCs) in the psoriatic epidermis, suggesting their role in the disease's pathogenesis. The study also highlights enhanced keratinocyte-immune cell interactions in psoriatic lesions, contributing to our understanding of psoriasis at the cellular level. Epidermal sheets from biopsies obtained from lesional and nonlesional skin of 5 untreated psoriasis patients and 3 healthy donors were subjected to partial dissociation preserving physical cell-cell interactions, followed by separation of CD45neg and CD45pos subsets by flow cytometry. Single-cell RNA sequencing was performed followed by Cell Interaction by Multiplet Sequencing (CIM-seq) analysis.