Project description:The functions of innate lymphoid cells (ILCs) in immune system are increasingly appreciated, whereas the early development of ILCs in human remains elusive. In this study, we sorted humanhematopoietic stem progenitor cells, lymphoid progenitors, presumed ILC progenitor/precursors and mature ILCs in the fetal hematopoietic, lymphoid and non-lymphoid tissues, from 8 to 12 PCW,for single-cell RNA-sequencing, followed by computational analysis and functional validation. We delineated the early phase of ILC development, from hematopoietic stem progenitor cells to multipotent lymphoid progenitors and to ILC progenitors, which mainly occurred in fetal liver and intestine. We further unveiled interleukin-3 receptor alpha (IL-3RA) as the surface marker for the lymphoid progenitors with T cell, B cell and ILC potentials. Notably, we determined the heterogeneity and tissue distribution of each ILC subpopulation, revealing the shared proliferating characteristics of the precursors of each ILC subtype. Additionally, a novel unconventional ILC2 subpopulation (CRTH2-CCR9+ ILC2) was identified in fetal thymus. Taken together, our study illuminates the precise cellular and molecular features underlying the stepwise formation of human fetal ILC hierarchy with remarkable spatiotemporal heterogeneity.
Project description:We identified a new type of bone marrow progenitors termed early innate lymphoid cell progenitor (EILP) using TCF-1 GFP reporter mice. We compared the transcriptomes of early innate lymphoid cell progenitors (EILP) with other early progenitors, including HSC, LMPP, CMP, CLP, ETP and DN3.
Project description:Innate lymphoid cells (ILC) in the small intestine govern immune homeostasis and protect the host against gut pathogens. While distinct cell-intrinsic signals have been identified that determine ILC development and differentiation, it has remained unclear which cell population regulates ILC sustenance. Using unbiased single cell RNA transcriptomic analysis of intestinal fibroblasts, we have identified a specialized Ccl19-expressing fibroblastic reticular cell (FRC) population that underpins solitary intestinal lymphoid tissue (SILT) structures including cryptopatches and isolated lymphoid follicles. Conditional ablation of lymphotoxin-β receptor (LTβR) signalling in SILT FRC impeded the maturation of isolated lymphoid follicles and blocked ILC maintenance through the downregulation of IL-7, consequently resulting in the elevated susceptibility to bacterial infection. Moreover, specific Ltbr ablation in FRC during adulthood revealed that constant LTβR-dependent FRC-ILC interaction is required to maintain SILT structures and ILC populations. Taken together, our study unveils a critical intestinal FRC niche that secures protective gut immunity.
Project description:Natural Killer (NK) cells at different developmental stages (common lymphoid progenitor (CLP), innate lymphoid cell progenitors (ILCP), and refined NK progenitor (NKP)) were collected from Vav1+iCre FOXO1,3flox/flox mice (C57BL/6 background). Total RNA was harvested and sequenced with a strand-specific paired-end RNA-seq protocol.
Project description:The precise lineage relationships between innate lymphoid cells (ILC) and the lymphoid tissue inducer (LTi) are poorly understood. Using single-cell multiplex transcriptional analysis of 100 lymphoid genes and single-cell cultures of fetal liver precursor cells, we identified the common proximal precursor to these lineages and showed that its bifurcation was precisely marked by the differential induction of the transcription factors PLZF and TCF1. Acquisition of individual ILC1/2/3-specific effector programs was initiated later, at the common ILC precursor (ILCP) stage, by transient expression of mixed ILC1/2/3 transcriptional patterns whereas, in contrast, LTi development did not go through multilineage priming. These findings provide novel insights into divergent mechanisms of ILC and LTi lineage differentiation and establish a high-resolution map of their development.
Project description:Single cell RNA-sequencing of human tonsil Innate lymphoid cells (ILCs) from three independent tonsil donors. Sequencing libraries were prepared from FACS sorted individual ILCs with the Smart-Seq2 protocol (Picelli et al. Nature Methods 2013)