Dynamic single-cell regulomes characterize human peripheral blood ILC subpopulations [scATAC-seq]
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ABSTRACT: Innate lymphoid cells (ILCs) are highly plastic immune cells that have been separated into 3 main subsets, characterized by distinct phenotypic and functional profiles. Using single cell approaches, heightened heterogeneity of mouse ILCs has been recently appreciated, imprinted by tissue signals that shape their transcriptome and epigenome. Intra-subset diversity has also been observed in human ILCs. However, combined transcriptomic and epigenetic analyses of single ILCs in humans are lacking. Here we show high transcriptional and epigenetic heterogeneity among human circulating ILCs in healthy individuals. We describe phenotypically distinct subclusters within main circulating ILC populations. We show diverse chromatin accessibility within main ILC subsets, compatible with differentially poised states. We validate the use of this healthy donor-based analysis as resource dataset to infer ILC changes occurring in disease conditions. Overall, our work provides new insights in the complex human ILC biology. We anticipate our work to be a starting point to facilitate hypothesis-driven studies in patients, without the need to perform single cell OMICs using precious patients’ material
Project description:Innate lymphoid cells (ILCs) are highly plastic immune cells that have been separated into 3 main subsets, characterized by distinct phenotypic and functional profiles. Using single cell approaches, heightened heterogeneity of mouse ILCs has been recently appreciated, imprinted by tissue signals that shape their transcriptome and epigenome. Intra-subset diversity has also been observed in human ILCs. However, combined transcriptomic and epigenetic analyses of single ILCs in humans are lacking. Here we show high transcriptional and epigenetic heterogeneity among human circulating ILCs in healthy individuals. We describe phenotypically distinct subclusters within main circulating ILC populations. We show diverse chromatin accessibility within main ILC subsets, compatible with differentially poised states. We validate the use of this healthy donor-based analysis as resource dataset to infer ILC changes occurring in disease conditions. Overall, our work provides new insights in the complex human ILC biology. We anticipate our work to be a starting point to facilitate hypothesis-driven studies in patients, without the need to perform single cell OMICs using precious patients’ material
Project description:Innate lymphoid cells (ILCs) represent innate versions of T helper and cytotoxic T cells that differentiate from committed ILC precursors (ILCP). Still, how ILCP relate to mature tissue-resident ILCs remains unclear. We identify ILCP that are present in the blood and all tested lymphoid and non-lymphoid human tissues. Human ILCP fail to express the signature transcription factors (TF) and cytokine outputs of mature NK cells and ILCs but are epigenetically poised to do so. Human ILCP robustly generate all ILC subsets in vitro and in vivo. While human ILCP express RAR related orphan receptor C (RORC), circulating ILCP can be found in RORC-deficient patients that retain potential for EOMES+ NK cells, T-BET+ ILC1, GATA-3+ ILC2 and for IL-22+ but not for IL-17A+ ILC3. We propose a model of tissue ILC differentiation (‘ILC-poiesis’) whereby diverse ILC subsets are generated in situ from ILCP in response to environmental stressors, inflammation and infection.
Project description:Innate lymphoid cells (ILCs) are highly plastic and predominantly mucosal tissue-resident cells that contribute to both homeostasis and inflammation depending on the microenvironment. The recent discovery of naïve-like tissue-resident ILCs suggests an ILC differentiation process that is akin to naïve T cell differentiation. Delineating the naïve-like ILC heterogeneity and the transcriptional, epigenetic and functional mechanisms that underlie ILC differentiation in tissues is crucial for understanding ILC biology in health and disease. Here we show that CD62L distinguishes two subsets of naïve-like CD45RA+ ILCs in tonsil tissue. While both subsets contain uni- and multipotent precursors of ILC1/NK cells and ILC3, CD62L+ ILCs resemble bona fide naïve ILCs with metabolism reminiscent of naïve T cells, lacking transcriptional and epigenetic signatures of mature ILCs. CD62L- ILCs are epigenetically similar to, but transcriptionally distinct from CD62L+ naïve-like ILCs including transcripts of cytokine signaling and metabolic pathways related to mature ILCs. A similar population of CD62L- quiescent ILCs with preferential differentiation capacity towards IL-22-producing ILC3 accumulate in the inflamed mucosa of patients with inflammatory bowel disease (IBD). These data suggest that naïve-like and quiescent ILCs are imprinted by their tissue microenvironment that poises their differentiation potential. Our findings identify restoration of homeostatic IL-22-producing ILC3 from CD62L- quiescent ILCs as a potential approach to improve tissue healing in IBD.
Project description:Background: Innate lymphoid cells (ILCs) comprise cytotoxic NK cells and “helper” ILCs (hILCs). Human hILC development is less characterized as compared to NK cells, although all ILCs are developmentally related. It has been reported that the immunosuppressive drugs glucocorticoids (GCs) regulate ILCs function, but whether they control ILCs differentiation from hematopoietic stem cells (HSCs) is unknown. Objective: We sought to analyze the effect of GCs on ILC development from HSCs. Methods: We exploited an in vitro system to generate and expand from peripheral blood (PB) HSCs a multipotent CD56+ ILC precursor able to differentiate into NK cells, ILC1s and ILC3s. We also analyzed ex vivo, at different time points, the PB of allogeneic HSC transplantation (HSCT) recipients who were or were not treated with GCs and compared ILC subset reconstitution. Results: We show that, in vitro, GCs favor the generation of NK cells from myeloid precursors, while they strongly impair lymphoid development. In support to these data, HSCT recipients who had been treated with GCs display a lower number of circulating hILCs, including the ILCP previously identified as a systemic substrate for tissue ILC differentiation. Conclusions: GCs impair the development of the CD117+ ILCP from CD34+ HSCs, while they do not affect the further steps of ILCP differentiation towards NK cells and hILC subsets. This reflects an association of GC treatment with a marked reduction of circulating hILCs in the recipients of HSCT.
Project description:The impact of the microenvironment on innate lymphoid cell (ILC)-mediated immunity in humans remains largely unknown. Here we used full-length Smart-seq2 single-cell RNA-sequencing to unravel tissue-specific transcriptional profiles and heterogeneity of CD127+ ILCs across four human tissues. Correlation analysis identified gene modules characterizing the migratory properties of tonsil and blood ILCs, and signatures of tissue-residency, activation and modified metabolism in gut and lung ILCs. Trajectory analysis revealed potential differentiation pathways from circulating and tissue-resident naïve ILCs to a spectrum of mature ILC subsets. In the lung we identified both CRTH2+ and CRTH2- ILC2 with lung-specific signatures, which could be recapitulated by alarmin-exposure of circulating ILC2. Finally, we describe unique TCR-V(D)J-rearrangement patterns of blood ILC1-like cells, revealing a subset of potentially immature ILCs with TCR-d rearrangement. In summary, we provide publicly available data as a resource for in-depth understanding of ILC-mediated immunity in humans, with implications for disease.
Project description:Human blood innate lymphoid cells (ILCs), which include ILCs and natural killer (NK) cells, derive from a common CD117+ILC precursor (ILCP). Yet, the relationship among the ILC subsets remains unclear. Bulk and single cell RNA-Seq and ATAC-Seq showed that blood ILC subsets cluster into ILC2s, ILCPs, a mixed cluster of CD56dim and CD56– NK cells, and a separate cluster of CD56hiNK cells that shares features with both ILCs and CD56dim/–NK cells. In surprising contrast to mice, tissue repair protein amphiregulin (AREG) was produced by human NK cells, with even higher levels in CD56hiNK cells than in ILCs. AREG expression in NK cells was driven by TCF7/WNT signaling and inhibited by TGFB1, a cytokine elevated in HIV-1+ people. Knockout of RUNX3, a WNT antagonist acting downstream of TGFB1, increased AREG production. Consistent with these findings, AREG+NK cells were decreased in people living with HIV-1. Additionally, functionally defective CD56–NK cells expanded in HIV-1+ people, in inverse correlation with CD56dimNK cells, ILCs, and CD4+T cells. Experiments in tissue culture and in humanized mice showed that CD56–NK cells derive from the epigenetically similar CD56dimNK cells, and that stimulation of MTOR by CD4+T cells or exogenous IL-2 prevents their expansion. These findings clarify how ILC subsets are related to each other and provide insight into how HIV-1 infection disrupts ILC homeostasis and contributes to pathology
Project description:Innate lymphoid cells (ILCs) have emerged as essential players in the skin-associated immune system in health and inflammatory skin diseases. Their low numbers and lack of specific markers hampered extensive characterization and consequently resulted in limited knowledge of their protein expression. Here, we combined flow cytometry and state-of-the-art proteomics to comprehensively describe the proteins constitutively expressed by ILC2 and ILC3 subsets derived from healthy human skin and peripheral blood. We quantified 6666 proteins from skin ILC and identified 608 differentially expressed proteins in the investigated subsets. In addition to the current analyses, highlighting new functions of ILC, the ILC proteomic libraries and the proteomes of the ILC2 and ILC3 subsets will serve as valuable resources for future analyses of ILC function and are available at http://skin.science.
Project description:Innate lymphoid cells (ILC) represent innate versions of T helper and cytotoxic T cells that differentiate from committed ILC precursors (ILCP). Still, how ILCP relate to mature tissue-resident ILCs remains unclear. We observed that a population of CD117+ ILC from peripheral blood (PB) of healthy donors does not represent any conical ILC subset, but expressed marker (CD117) commonly expressed by hemato-lymphoid progenitors. We therefore hypothesized PB CD117+ ILC might include uncommitted lymphoid precursors. In order to further understand the identity of PB CD117+ ILC, we profiled the transcriptome of highly purified circulating CD117+ ILC compared to CD34+ HSC, the latter representing immature hematopoietic progenitors with multi-lineage potential. Clear differences in gene expression profiles emerged, with a large cluster of 1540 genes expressed at substantially higher levels in CD117+ ILC. In contrast, CD34+ HSC cells highly expressed genes involved in the broad development of diverse hematopoietic lineages. Compared to HSC, CD117+ ILC express high levels of TF that have been shown to be essential for murine ILC development and we did not detect transcripts characteristic of T and B cells development. Transcriptomic analysis suggested that CD117+ ILC represent lymphoid-biased progenitors carrying a TF expression profile resembling a multi-potent ILC precursor (ILCP).
Project description:Innate lymphoid cells (ILC) are tissue-resident effector cells with important roles in tissue homeostasis, protective immunity and inflammatory disease. Here we investigated the role of the transcription factor Bcl6 in small intestinal innate lymphoid cells. Specifically, we performed single-cell RNA-seq on total small intestine lamina propria ILCs from tamoxifen-treated Id2-CreERT2 ROSA26-tdRFP Bcl6-fl/fl mice and Id2-CreERT2 ROSA26-tdRFP controls.