To summarize current knowledge regarding the origin, composition, phenotype, and dynamics of human epidermal TRM cells.
Approach:
Review of Literature: The review focuses on studies performed in human tissues to understand the role of epidermal TRM cells.
Key Findings:
The human epidermis contains abundant populations of conventional and regulatory TRM cells.
Epidermal TRM cells are enriched for CD8+CD69+CD103+ populations, including specialized cytotoxic subsets expressing CD49a and CD101.
Epidermal immune homeostasis is maintained through interactions among conventional TRM cells, regulatory TRM cells, Langerhans cells, and keratinocytes.
Epidermal TRM cells are implicated in diseases such as HIV infection, fixed drug eruption, vitiligo, and alopecia areata.
The epidermis should be regarded as an autonomous immunological compartment.
Interpretation:
Limitations:
Many fundamental concepts of TRM biology were established in murine models, which may not fully represent human skin dynamics. Caution is required when extrapolating findings from animal models to human skin.
Conclusion:
A deeper understanding of epidermal immune organization may provide insights into epidermis-centered diseases.
