Single-cell RNA sequencing of mouse epidermal Langerhans cells under injured and healthy conditions

Langerhans cells (LCs) are a specialized subset of dendritic cells that reside in the basal layer of the epidermis. LCs form a dense network across the skin, where LCs serve as key sentinels by detecting antigens from the environment and sensing damage to the epidermis. Despite extensive and persistent research, many immunological and physiological aspects of LCs functioning remain incompletely understood. In our study, we combined the advantages of single-cell RNA sequencing, intravital microscopy, and deep experimental approach to create protocols for the mass activation of LCs and the rapid isolation of the maximum viable LCs number. We present a high-resolution single-cell transcriptomic dataset of over 22,000 epidermal LCs, including injured and homeostatic conditions. We have, for the first time, clearly identified and characterized the distinct populations of LCs present in both homeostatic and injured epidermis. Most notably, we discovered a specific population of activated LCs that displays several unique features, including the activation of the complement system, a key component of the skin’s innate immune response. Single-cell RNA libraries were generated using the 10x Genomics platform from Langerhans cells isolated from mouse ear epidermis. Samples included untreated sample, skin treated with multiple microneedle-array punches and skin treated with a mixture of acetone, croton oil and olive oil. Libraries were sequenced on the Illumina NovaSeq X using 100 bp single-end reads (10B 100 SR).