Spatial transcriptomics combined with single-cell RNA-sequencing unravels the complex inflammatory cell network in atopic dermatitis [ST]

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease with complex pathogenesis. Using spatial and single-cell transcriptomics of whole skin biopsy and suction blister material, we investigated the cellular and molecular features of the leukocyte-infiltrated area in AD. We identified unique clusters of fibroblasts, dendritic cells, macrophages, and T cells in the lesional AD skin and molecular interactions between these cells. The leukocyte-infiltrated areas in lesional AD skin showed upregulation of COL6A5, COL4A1, TNC, IL32, CCL19 in COL18A1-expressing fibroblasts. Additionally, M2 macrophages expressed CCL13 and CCL18 in the same localization. Ligand–receptor interaction analysis of the spatial transcriptome identified a neighboring infiltration and interaction between activated COL18A1-expressing fibroblasts, activated CCL13- and CCL18-expressing M2 macrophages, CCR7- and LAMP3-expressing DCs, and T cells. As observed in skin lesions, serum levels of TNC and CCL18 were significantly elevated in AD and correlated with clinical disease severity. Overall design: Spatial Transcriptomics (Visium Spatial Gene Expression; 10X Genomics) of human skin biopsy samples. 14 skin biopsy samples were collected from 7 atopic dermatitis patients, 1 from lesional and 1 from non-lesional skin per patient. In addition, 6 skin biopsy samples were collected from 6 healthy donors to serve as a control.