Single-cell spatial transcriptomic analysis of human skin anatomy

The skin is the largest human organ and a site of substantial disease burden, yet its cellular and molecular organization across the body is largely undefined. Here we construct an organ-wide single-cell spatial atlas of ~1.2 million cells from normal adult human skin, resolving the location of 45 cell types across 114 samples encompassing 15 anatomic sites. We uncover site-specific stereotypic cell-type composition and their organization into ten multicellular neighborhoods, most notably a perivascular neighborhood reminiscent of skin-associated lymphoid tissue. Within this neighborhood, ligand-receptor (L-R) analyses identify a central role for tumor necrosis factor in maintaining CCL19⁺ perivascular fibroblasts, highlighting homeostatic immune-stromal crosstalk. Finally, comparing neighborhood dynamics in spatial transcriptomics of skin disease, we find pan-disease immune alterations in this perivascular neighborhood, suggesting spatial compartmentalization of pathogenic activity. Thus, multicellular neighborhoods underlie the skin's multiscale molecular to macroanatomic organization, orchestrate cell-cell interactions and anatomic site specialization and exhibit architectural disruption in disease.