Single Cell and Spatial Sequencing Characterizes Cell Type Composition and Cell-Cell Interaction in Psoriasis

The immunopathogenesis of psoriasis, a common chronic inflammatory disease of the skin, is still incompletely understood. Here we demonstrate, using a combination of single-cell and spatial-sequencing, that psoriatic fibroblasts, a hitherto unappreciated participant in psoriasis pathogenesis, contribute to the immune network in psoriasis through transition to a pro-inflammatory state characterized by CCL19 and CCL13. Fibroblasts interact with three other main cell-types that are in close proximity: keratinocytes, T cells and myeloid cells, that also interact with each other. In addition, our data demonstrates striking compartmentalization of inflammatory responses in distinct layers of the psoriatic epidermis, including IL-17A responses and autocrine IL-36 autoinflammatory activity within the supraspinous layer. Lastly, our data defined the T cell and myeloid populations involved in psoriasis, including enrichment of CD8+ IL17A expressing T cells, CD16+ dendritic cells, and LAMP3+ dendritic cells. These data provide an unprecedented view of psoriasis pathogenesis, which expands our understanding of the critical cellular players to include inflammatory fibroblasts as well as their cell-cell interactions, defines the spatial compartmentalization of specific inflammatory processes, together a unique resource for future investigations. To study cell type compositon and transcription changes in normal skin from healthy donors, peripheral normal skin from psoriasis patients and psoriatic skin from psoriasis patients