PDGFRa+gp38+ mesenchymal cells in the peripheral tissues support terminal differentiation of ILC2 originated from fetal liver progenitor cells.

Group 2 innate lymphoid cells (ILC2) are tissue-resident innate lymphocytes that are derived from common lymphoid progenitor (CLP). While specific progenitors and transcription factors essential for ILC2 differentiation have been well studied, external factors that regulate the commitment from CLP to ILC lineage, site that promote ILC2 terminal differentiation, and stromal cells that provide optimal microenvironment for ILC2 specific development are not fully understood. we demonstrated that the three key external factors such as concentration of IL-7 and the strength and duration of Notch signaling conditionally determined the fate of CLP toward T cell, B cell, or ILC lineages, which seems to be an important process from CLP to CHILP differentiation in the fetal liver. Furthermore, we identified ILC progenitors lacking the developmental potential to become T or B cells, and KLRG1- immature ILC2 that require STAT5 for functional maturation in the mesentery. We also identified PDGFRa+gp38+ mesenchymal cells in the mesentery that support ILC2 differentiation from ILC progenitors but not from CLP. Finally, single-cell RNA-sequencing (scRNA-seq) analysis of mesenteric cells demonstrated that PDGFRa+gp38+ cells are heterogeneous populations. Collectively, our result suggested that early differentiation of ILC2 occurs in the primary lymphoid organ with regulation of environmental factors, and final differentiation occurs in the peripheral tissues once after CHILP migrate into the periphery. Overall design: Duplicate samples (mouse 1 and mouse 2) were processed for single cell-based RNA sequencing with Illumina HiSeq 2500 with 50 paired-end reads, using barcorded RNA library.

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Koga S, Hozumi K, Hirano KI, Yazawa M, Terooatea T, Minoda A, Nagasawa T, Koyasu S, Moro K