Preferential Perinatal Development of Skin-Homing NK1.1 Innate Lymphoid Cells for Regulation of Cutaneous Microbiota Colonization.

Proper immune cell development at early ontogenic stages is critical for life-long health. How resident immune cells are established in barrier tissues at neonatal stages to provide early protection is an important but still poorly understood question. We herein report that a developmentally programmed preferential generation of skin-homing group 1 innate lymphoid cells (ILC1s) at perinatal stages helps regulate early skin microbiota colonization. We found that a population of skin-homing NK1.1 ILC1s was preferentially generated in the perinatal thymi of mice. Unique thymic environments and progenitor cells are responsible for the preferential generation of skin-homing NK1.1 ILC1s at perinatal stages. In the skin, NK1.1 ILC1s regulate proper microbiota colonization and control the opportunistic pathogen Pseudomonas aeruginosa in neonatal mice. These findings provide insight into the development and function of tissue-specific immune cells at neonatal stages, a critical temporal window for establishment of local tissue immune homeostasis.