Innate Lymphoid Cells Subsets Research Articles

Presence of innate lymphoid cells in allogeneic hematopoietic grafts correlates with reduced graft-versus-host disease

BackgroundAllogeneic hematopoietic cell transplantation (HCT) can be devastating when graft-versus-host disease (GvHD) develops. GvHD is characterized by mucosal inflammation due to breaching of epithelial barriers. Innate lymphoid cells (ILCs) are immune modulatory cells that are important in the maintenance of epithelial barriers, via their production of interleukin (IL)-22 and their T cell suppressive properties. After chemo- and radiotherapy, ILCs are depleted, and recovery after remission-induction therapy and after allogeneic HCT is slow and incomplete in a significant number of patients, which is associated with an increased risk to develop acute GvHD. ObjectiveTo investigate whether the presence of mature ILCs within G-CSF–mobilized HCT grafts is correlated with the development of acute GvHD after allogeneic HCT. Study DesignWe analyzed ILCs in a cohort of 36 patients who received allogeneic HCT for a hematologic malignancy, by flow-cytometric immune-phenotyping of prospectively collected, cryopreserved peripheral blood mononuclear cells (PBMCs) and donor-derived HCT grafts collected for the same patients. Biased analysis, with ILCs defined as CD3−lineage−CD45+CD127+CD161+ lymphocytes, was performed using FlowJo version 10 software. Unbiased analysis was done using FlowSOM, which uses a self-organizing map (SOM) with a minimal spanning tree (MST) to define and visualize different clusters present in the samples. ResultsRemission-induction therapy significantly depleted ILCs from the blood, and patients who had a relatively low percentage of ILCs before allogeneic HCT were significantly more prone to develop acute GvHD, confirming previous findings in a separate cohort. Allogeneic HCT grafts, which were all obtained from the blood of G-CSF–mobilized healthy donors, contained ILCs at a frequency very similar to the peripheral blood of healthy individuals. The ILC subset composition was also comparable to that of the blood of healthy individuals, with the exception of NKp44+ ILC3s, which were significantly more abundant in HCT grafts. The relative ILC content of the graft tended to correlate with ILC reconstitution after allogeneic HCT, suggesting that peripheral expansion of transplanted mature ILCs may contribute to early ILC reconstitution after allogeneic HCT. Patients who received a relatively ILC-poor HCT graft had a significantly increased risk to develop acute GvHD, compared with patients who received relatively ILC-rich allogeneic HCT grafts. Unbiased phenotypic analysis with the FlowSOM algorithm confirmed that allogeneic HCT grafts of patients who developed acute GvHD contained a lower frequency of ILCs that clustered in NKp44+ ILC3 signature groups. ConclusionThe presence of ILCs in allogeneic HCT grafts is associated with a reduced risk to develop acute GvHD. These data suggest that enhancement of ILC reconstitution of ILC3s in particular, for example via adoptive transfer of ILCs, may prevent acute GvHD and has the potential to improve outcome of allogeneic HCT recipients.

Change of innate lymphoid cell subsets in peripheral bloods and ascites in liver cirrhotic patients complicated with spontaneous bacterial peritonitis

Objective: To investigate the change of innate lymphoid cells (ILC) subsets in peripheral blood and ascites in liver cirrhotic patients complicated with spontaneous bacterial peritonitis (SBP). Methods: The data of 62 patients with liver cirrhosis admited to the Zhumadian Central Hospital from November 2019 to November 2020 were analyzed. Among them, 41 cases were complicated with untainted ascites (untainted ascites group), while the other 21 cases were complicated with SBP (SBP group). Meanwhile, 20 cases of controls who received healthy examination in the same period were also enrolled (control group). Peripheral blood mononuclear cell (PBMC) was isolated from peripheral blood of all patients and controls. Mononuclear cell in ascites was isolated from patients with liver cirrhosis. The percentage of ILC1, ILC2, and ILC3 subsets in PBMC and mononuclear cell in ascites were measured by flow cytometry. CD3-CD19-CD20-CD14- cells (lin-cells) were purified from ascites and were stimulated with lipopolysaccharide (LPS) for 24 h. The transcription factor T-bet, GATA3, and RORγt mRNA relative level in lin-cells was semi-quantified by real-time PCR. Cytokine level in the supernatants was measured by enzyme linked immunosorbent assay. Differences of ILC subsets in peripheral blood and ascites were compared among groups. Results: There were twenty-nine males and twelve females in untainted ascites group, aged M(Q1,Q3) 49(33, 78) years. There were twelve males and nine females in SBP group, aged 50(37, 76) years. There were eleven males and nine females in control group, aged 48(32, 69) years. lin-CD45+CD161+CD127+ ILC cells could be detected in both peripheral blood and ascites. There was no significant difference in total ILC percentage within PBMC among untainted ascites group, SBP group, and control group (P=0.235). There was also no significant difference of total ILC percentage within mononuclear cells in ascites between untainted ascites group and SBP group (P=0.232). The differences were not statistically significant of peripheral CD117-CRTh2-ILC1, CRTh2+ILC2, or CD117+CRTh2-ILC3 within peripheral ILC among untainted ascites group, SBP group, and control group (all P>0.05). ILC1 percentage in ascites was up-regulated in SBP group compared with untainted ascites group (35.69%±3.39% vs 26.40%±3.85%, P<0.001), while ILC2 in ascites was down-regulated in SBP group (36.83%±7.70% vs 48.35%±9.45%, P<0.001). There was no statistical difference in ILC3 percentage in ascites between the two groups (P=0.230). T-bet mRNA relative level and IFN-γ production by lin- cells from ascites were elevated in response to LPS stimulation in SBP group compared with untainted ascites group (both P<0.001). GATA3 mRNA relative level and IL-5/IL-13 secretion by lin-cells from ascites were reduced in SBP group compared with untainted ascites group (both P<0.05). There was no significant difference of RORγt mRNA relative level or IL-17/IL-22 expression between the two groups (both P>0.05). Conclusion: Peripheral ILC subsets do not change in liver cirrhosis patients with SBP. ILC1 percentage is up-regulated, and ILC2 percentage is down-regulated in ascites in liver cirrhosis patients with SBP.

Innate Lymphoid Cells in Autoimmune Diseases.

Innate lymphoid cells (ILC) are a heterogeneous group of immune cells characterized by lymphoid morphology and cytokine profile similar to T cells but which do not express clonally distributed diverse antigen receptors. These particular cells express transcription factors and cytokines reflecting their similarities to T helper (Th)1, Th2, and Th17 cells and are therefore referred to as ILC1, ILC2, and ILC3. Other members of the ILC subsets include lymphoid tissue inducer (LTi) and regulatory ILC (ILCreg). Natural killer (NK) cells share a common progenitor with ILC and also exhibit a lymphoid phenotype without antigen specificity. ILC are found in low numbers in peripheral blood but are much more abundant at barrier sites such as the skin, liver, airways, lymph nodes, and the gastrointestinal tract. They play an important role in innate immunity due to their capacity to respond rapidly to pathogens through the production of cytokines. Recent evidence has shown that ILC also play a key role in autoimmunity, as alterations in their number or function have been identified in systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Here, we review recent advances in the understanding of the role of ILC in the pathogenesis of autoimmune diseases, with particular emphasis on their role as a potential diagnostic biomarker and as therapeutic targets.

Circulating Innate Lymphoid Cells Exhibit Distinctive Distribution During Normal Pregnancy

Over the past decades, the investigation of innate lymphoid cells (ILCs) has revealed their significance in successful pregnancy. Sex hormones, such as estradiol and progesterone, show specific changes during pregnancy and modulate both adaptive and innate immune systems. ILC subset distribution in peripheral blood of pregnant women and its potential association with sex hormone levels have not been well revealed. Peripheral blood was obtained from healthy non-pregnant, early-pregnant, and late-pregnant women. Radioimmunoassay was performed to measure plasma estradiol and progesterone levels. The levels of type 1 ILCs (ILC1s), type 2 ILCs (ILC2s), type 3 ILCs (ILC3s), and total ILCs as well as estrogen and progesterone receptors of ILC2s in peripheral blood were analyzed using flow cytometry. The proportion of total ILCs and distribution of ILC subsets in peripheral blood changed dynamically during pregnancy. Compared to non-pregnant women, late-pregnant women displayed significantly higher proportion of circulating ILCs, among which ILC2s accounted for the majority in late-pregnant women while a smaller part in others, and ILC3s displayed the opposite. Plasma estradiol and progesterone levels elevated while pregnancy proceeded and the expression of their receptors in ILC2s increased consisted with the proportion of circulating ILC2s. Our work first observed the existence of progesterone receptors in human circulating ILC2s and revealed the distribution pattern of circulating ILC subsets and their interrelation with plasma sex hormone levels during pregnancy. Our results suggested that the estradiol and progesterone levels might partly influence the distribution of circulating ILC subsets and implied the interplay between circulating ILCs and pregnancy.

Isolation of Innate Lymphoid Cells from Murine Intestinal Lamina Propria.

Natural killer (NK) cells are innate cytotoxic immune cells essential for mediating first-line defense against various environmental antigens. With the discoveries of other subsets of innate lymphocytes over the last decade, NK cells are categorized as innate lymphoid cells (ILC) and as the innate counterparts of cytotoxic T cells. Besides NK cells, ILCs are classified into three groups distinguished by their dependence on distinct transcription factors for development and unique effector functions. Subsets of ILCs share many surface proteins that, however, have initially been identified as NK cell markers, making them hard to be distinguished for detailed investigations. Here, we describe a method to identify and individually isolate subsets of innate lymphoid cells from gut lamina propria using cell surface markers.

ILC Differentiation in the Thymus.

The thymus provides a microenvironment conducive to the differentiation of innate lymphoid cells (ILCs), supplying IL-7 as well as Notch ligands. Early T cell precursors also express a number of obligatory transcription factors essential for ILC differentiation. Therefore, the thymus could be a powerhouse for ILC production. However, coordinated regulation by transcription factors and T cell receptor signaling events ensure that T cell production is the dominating output of the thymus. One group of the key regulators are the basic helix-loop-helix E protein transcription factors and their inhibitors, Id proteins. When E protein activities are downregulated, T cell development is blocked and massive ILC2 production occurs in the thymus. Normally, the thymus indeed generates a small number of ILCs, mostly group 2 ILCs (ILC2s). It has been shown in vitro that ILC2s can be differentiated from multipotent early T cell progenitors (ETPs) as well as committed T cell precursors. Moreover, thymus-derived ILC precursors have been found in the blood of adult mice. They then home to peripheral tissues and undergo differentiation into distinct ILC subsets. These ILC precursors may replenish tissue ILC pools in steady state or on demand in pathophysiological conditions. Collectively, emerging evidence suggests that the thymus plays an underappreciated role in ILC homeostasis.

Circulating CCR6+ILC proportions are lower in multiple sclerosis patients.

The role of innate lymphoid cells (ILC), particularly helper ILC, in the pathogenesis of multiple sclerosis (MS) is not well understood. Here, we present a comprehensive analysis of peripheral ILC subsets in MS patients prior and after alemtuzumab administration using mass cytometry. Circulating ILC were analysed by mass cytometry in MS patients before and after alemtuzumab. These were compared with non-MS controls. MS-related shifts among ILC immunophenotypes were further elucidated by fast interpolation-based t-SNE (Flt-SNE) dimensionality reduction. Neither natural killer (NK) cells nor helper ILC (ILC1, ILC2 and ILC3) levels were altered following alemtuzumab treatment. However, CD56bright NK cell expansions were observed in relapsing patients. MS patients prior to alemtuzumab further displayed proportional shifts from ILC1 to ILC2, with MS-associated decreases in CCR6+ helper ILC proportions. CD56bright NK cells during relapse indicate an immediate response to disease reactivation, while CCR6-related shifts among helper ILC suggest altered ILC migration to the CNS during MS.

CD5 Surface Expression Marks Intravascular Human Innate Lymphoid Cells That Have a Distinct Ontogeny and Migrate to the Lung.

Innate lymphoid cells (ILCs) contribute to immune defense, yet it is poorly understood how ILCs develop and are strategically positioned in the lung. This applies especially to human ILCs due to the difficulty of studying them in vivo. Here we investigated the ontogeny and migration of human ILCs in vivo with a humanized mouse model (“MISTRG”) expressing human cytokines. In addition to known tissue-resident ILC subsets, we discovered CD5-expressing ILCs that predominantly resided within the lung vasculature and in the circulation. CD5+ ILCs contained IFNγ-producing mature ILC1s as well as immature ILCs that produced ILC effector cytokines under polarizing conditions in vitro. CD5+ ILCs had a distinct ontogeny compared to conventional CD5- ILCs because they first appeared in the thymus, spleen and liver rather than in the bone marrow after transplantation of MISTRG mice with human CD34+ hematopoietic stem and progenitor cells. Due to their strategic location, human CD5+ ILCs could serve as blood-borne sentinels, ready to be recruited into the lung to respond to environmental challenges. This work emphasizes the uniqueness of human CD5+ ILCs in terms of their anatomical localization and developmental origin compared to well-studied CD5- ILCs.

CD200R1 Distinguishes Uncommitted Precursors from Functionally Mature NK Cells within the Human Tonsil Stage 4A NK Cell Population

Natural killer (NK) cells are cytotoxic innate lymphoid cells (ILCs) whose development and anti-tumor functions can be critical for the successful treatment and long-term disease-free survival of patients with hematologic malignancies. In humans, NK cells derive from bone marrow resident hematopoietic progenitor cells that traffic to secondary lymphoid tissues (SLTs) where they complete their terminal differentiation and maturation through a series of developmental stages before returning to the blood as mature NK cells. Although major stages of human NK cell development in SLTs have been clearly defined according to the differential surface expression of CD34, CD117, CD94, NKp80, CD16, and CD57 among lineage antigen (Lin) negative lymphocytes, continued investigation has revealed additional phenotypic and functional heterogeneity at each developmental stage. Through extensive ex vivo single-cell RNA sequencing and flow cytometry analyses we have identified two subsets of tonsil-resident Lin -CD34 -CD117 +/-CD94 +NKp80 -CD16 -CD57 - stage 4A NK cells. These two subsets differ in their expression of the inhibitory receptor, CD200R1, which is not expressed by mature NK cells in the peripheral blood from healthy individuals. The majority of stage 4A cells expressed high amounts of surface CD200R1, which correlated with low gene and undetectable protein expression of intracellular cytolytic granules (perforin and granzymes A, B, K, and M), killer immunoglobulin-like receptors (KIRs), and transcription factors required for terminal NK cell maturation (EOMES, T-BET). In addition, upon ex vivo stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin, CD200R1 + stage 4A NKDIs did not produce interferon-gamma (IFN-g), a hallmark feature of mature NK cells. In contrast, many CD200R1 - stage 4A cells constitutively expressed perforin, granzymes, EOMES, and/or T-BET; many expressed KIRs; and many produced IFN-g upon ex vivo stimulation. Furthermore, the frequency of KIR + cells among CD200R1 - stage 4A cells was significantly higher than that among autologous tonsil stage 4B NK cells (Lin -CD34 -CD117 +/-CD94 +NKp80 +CD16 -CD57 -) (20.8 ± 1.65 vs. 8.12 ± 1.66; p < 0.01; n = 14), suggesting that as a population CD200R1 - stage 4A cells are potentially out of sequence in terms of the linear NK cell developmental pathway. Based on these ex vivo findings, we hypothesized that CD200R1 + stage 4A cells represent NK cell precursors, whereas the CD200R1 - stage 4A population contains more mature NK cells that lack NKp80, CD16, and CD57. To further address this hypothesis and to determine their ex vivo potentials for NK cell and non-NK ILC differentiation, we cultured CD200R1 + and CD200R1 - stage 4A cells in vitro in the presence of OP9-DL1 stroma and recombinant human IL-7 and IL-15, conditions previously shown to support all human ILC and NK cell subset differentiation. Under these conditions, both stage 4A populations generated NKp80 + NK cells in bulk and single-cell clonal assays, whereas neither population gave rise to ILC2s (CD294 +) which precede stage 4A NK cells in the developmental scheme. However, while the majority of cultures derived from CD200R1 + stage 4A clones contained ILC3s (CD94 -NKp44 +), significantly fewer clones from CD200R1 - stage 4A cells produced ILC3s (7 of 26 CD200R1 - clones vs. 20 of 23 CD200R1 + clones; p = 0.000587). Moreover, none of the CD200R1 - stage 4A-derived clonal cultures that contained KIR + NK cells contained ILC3s, suggesting that the majority of CD200R1 - stage 4A cells are lineage committed NK cells. Collectively, these data further characterize the heterogeneity of the human tonsil stage 4A NK cell population and identify CD200R1 as a marker distinguishing uncommitted precursor cells from a minor population of cells with otherwise mature NK-associated phenotype and function. In light of the role of CD200R1 in regulating lymphocyte functions in the setting of cancer, further research is warranted to determine its potential role(s) in regulating human NK cell development. DisclosuresBlachly: KITE: Consultancy, Honoraria; INNATE: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; AstraZeneca: Consultancy, Honoraria.

Glucocorticoids inhibit human hematopoietic stem cell differentiation toward a common ILC precursor

Innate lymphoid cells (ILCs) comprise cytotoxic natural killer (NK) cells and helper ILCs (hILCs). Human hILC development is less characterized as compared with that of NK cells, although all ILCs are developmentally related. It has been reported that the immunosuppressive drugs glucocorticoids (GCs) regulate ILC function, but whether they control ILC differentiation from hematopoietic stem cells (HSCs) is unknown. This study sought to analyze the effect of GCs on ILC development from HSCs. This study exploited an invitro system to generate and expand from peripheral blood HSCs a multipotent CD56+ ILC precursor able to differentiate into NK cells, ILC1s, and ILC3s. We also analyzed exvivo, at different time points, the peripheral blood of recipients of allogeneic HSC transplantation who were or were not treated with GCs and compared ILC subset reconstitution. Invitro, GCs favor the generation of NK cells from myeloid precursors, while they strongly impair lymphoid development. In support of these data, recipients of HSC transplantation who had been treated with GCs display a lower number of circulating hILCs, including the ILC precursor (ILCP) previously identified as a systemic substrate for tissue ILC differentiation. GCs impair the development of the CD117+ ILCP from CD34+ HSCs, while they do not affect the further steps of ILCP differentiation toward NK cells and hILC subsets. This reflects an association of GC treatment with a marked reduction of circulating hILCs in the recipients of HSC transplantation.

The Reaction of Innate Lymphoid Cells in the Mouse Female Genital Tract to Chlamydial Infection.

Innate lymphoid cells (ILCs) comprise five distinct subsets. ILCs are found at mucosal barriers and may fight invading pathogens. Chlamydia is an intracellular bacterium that infects the mucosa of the genital tract and can cause severe tissue damage. Here, we used a mouse infection model with Chlamydia muridarum to measure the reaction of genital tract ILCs to the infection. Tissue-resident natural killer (NK) cells were the largest group in the uninfected female genital tract, and their number did not substantially change. Conventional NK cells were present in the greatest numbers during acute infection, while ILC1s continuously increased to high numbers. ILC2 and ILC3s were found at lower numbers that oscillated by a factor of 2 to 4. The majority of ILC3s transdifferentiated into ILC1s. NK cells and ILC1s produced gamma interferon (IFN-γ) and, rarely, tumor necrosis factor (TNF), but only early in the infection. Lack of B and T cells increased ILC numbers, while the loss of myeloid cells decreased them. ILCs accumulated to a high density in the oviduct, a main site of tissue destruction. ILC subsets are part of the inflammatory and immune reaction during infection with C. muridarum and may contribute to tissue damage during chlamydial infection.

The Regulatory Activity of Noncoding RNAs in ILCs.

Innate lymphoid cells (ILCs) are innate lymphocytes playing essential functions in protection against microbial infections and participate in both homeostatic and pathological contexts, including tissue remodeling, cancer, and inflammatory disorders. A number of lineage-defining transcription factors concurs to establish transcriptional networks which determine the identity and the activity of the distinct ILC subsets. However, the contribution of other regulatory molecules in controlling ILC development and function is also recently emerging. In this regard, noncoding RNAs (ncRNAs) represent key elements of the complex regulatory network of ILC biology and host protection. ncRNAs mostly lack protein-coding potential, but they are endowed with a relevant regulatory activity in immune and nonimmune cells because of their ability to control chromatin structure, RNA stability, and/or protein synthesis. Herein, we summarize recent studies describing how distinct types of ncRNAs, mainly microRNAs, long ncRNAs, and circular RNAs, act in the context of ILC biology. In particular, we comment on how ncRNAs can exert key effects in ILCs by controlling gene expression in a cell- or state-specific manner and how this tunes distinct functional outputs in ILCs.

195 Proteomic Analyses of ILC2 and ILC3 from Human Skin and Peripheral Blood Reveal Distinctive Phenotypes and Functions

Innate lymphoid cells (ILC) are important members of the skin-associated immune system. Despite their central role in healthy skin and inflammatory skin diseases, the constituent proteins of ILC have not been characterized in-depth. Here, we purified the two main human skin ILC subsets — CRTH2+ ILC2 and CRTH2–CD117+NCR2– ILC3 — from healthy skin (n=10) by flow cytometry and used state-of-the-art mass spectrometry-based proteomics for in-depth proteome analysis. For comparison, we included blood-derived ILC analogues from healthy donors in our study.

Discovery of LYC-55716: A Potent, Selective, and Orally Bioavailable Retinoic Acid Receptor-Related Orphan Receptor-γ (RORγ) Agonist for Use in Treating Cancer.

Retinoic acid receptor-related orphan receptor γ (RORc, RORγ, or NR1F3) is the nuclear receptor master transcription factor that drives the function and development of IL-17-producing T helper cells (Th17), cytotoxic T cells (Tc17), and subsets of innate lymphoid cells. Activation of RORγ+ T cells in the tumor microenvironment is hypothesized to render immune infiltrates more effective at countering tumor growth. To test this hypothesis, a family of benzoxazines was optimized to provide LYC-55716 (37c), a potent, selective, and orally bioavailable small-molecule RORγ agonist. LYC-55716 decreases tumor growth and enhances survival in preclinical tumor models and was nominated as a clinical development candidate for evaluation in patients with solid tumors.

An in vitro platform supports generation of human innate lymphoid cells from CD34+ hematopoietic progenitors that recapitulate ex vivo identity

Innate lymphoid cells (ILCs) are critical effectors of innate immunity and inflammation, whose development and activation pathways make for attractive therapeutic targets. However, human ILC generation has not been systematically explored, and previous invitro investigations relied on the analysis of few markers or cytokines, which are suboptimal to assign lineage identity. Here, we developed a platform that reliably generated human ILC lineages from CD34+ hematopoietic progenitors derived from cord blood and bone marrow. We showed that one culture condition is insufficient to generate all ILC subsets, and instead, distinct combination of cytokines and Notch signaling are essential. The identity of natural killer (NK)/ILC1s, ILC2s, and ILC3s generated invitro was validated by protein expression, functional assays, and both global and single-cell transcriptome analysis, recapitulating the signatures and functions of their exvivo ILC counterparts. These data represent a resource to aid in clarifying ILC biology and differentiation.

Natural Killer Cells and Type 1 Innate Lymphoid Cells in Hepatocellular Carcinoma: Current Knowledge and Future Perspectives.

Natural killer (NK) cells and type 1 innate lymphoid cells (ILC1) are specific innate lymphoid cell subsets that are key for the detection and elimination of pathogens and cancer cells. In liver, while they share a number of characteristics, they differ in many features. These include their developmental pathways, tissue distribution, phenotype and functions. NK cells and ILC1 contribute to organ homeostasis through the production of key cytokines and chemokines and the elimination of potential harmful bacteria and viruses. In addition, they are equipped with a wide range of receptors, allowing them to detect “stressed cells’ such as cancer cells. Our understanding of the role of innate lymphoid cells in hepatocellular carcinoma (HCC) is growing owing to the development of mouse models, the progress in immunotherapeutic treatment and the recent use of scRNA sequencing analyses. In this review, we summarize the current understanding of NK cells and ILC1 in hepatocellular carcinoma and discuss future strategies to take advantage of these innate immune cells in anti-tumor immunity. Immunotherapies hold great promise in HCC, and a better understanding of the role and function of NK cells and ILC1 in liver cancer could pave the way for new NK cell and/or ILC1-targeted treatment.

A Gata3 enhancer necessary for ILC2 development and function

The type 2 helper effector program is driven by the master transcription factor GATA3 and can be expressed by subsets of both innate lymphoid cells (ILCs) and adaptive CD4+ T helper (Th) cells. While ILC2s and Th2 cells acquire their type 2 differentiation program under very different contexts, the distinct regulatory mechanisms governing this common program are only partially understood. Here we show that the differentiation of ILC2s, and their concomitant high level of GATA3 expression, are controlled by a Gata3 enhancer, Gata3 +674/762, that plays only a minimal role in Th2 cell differentiation. Mice lacking this enhancer exhibited defects in several but not all type 2 inflammatory responses, depending on the respective degree of ILC2 and Th2 cell involvement. Our study provides molecular insights into the different gene regulatory pathways leading to the acquisition of the GATA3-driven type 2 helper effector program in innate and adaptive lymphocytes.

ILC1s and ILC3s Exhibit Inflammatory Phenotype in Periodontal Ligament of Periodontitis Patients.

Innate lymphoid cells (ILCs) are emerging as important players in inflammatory diseases. The oral mucosal barrier harbors all ILC subsets, but how these cells regulate the immune responses in periodontal ligament tissue during periodontitis remains undefined. Here, we show that total ILCs are markedly increased in periodontal ligament of periodontitis patients compared with healthy controls. Among them, ILC1s and ILC3s, particularly NKp44+ILC3 subset, are the predominant subsets accumulated in the periodontal ligament. Remarkably, ILC1s and ILC3s from periodontitis patients produce more IL-17A and IFN-γ than that from healthy controls. Collectively, our results highlight the role of ILCs in regulating oral immunity and periodontal ligament inflammation and provide insights into targeting ILCs for the treatment of periodontitis.

A multilayered immune system through the lens of unconventional T cells.

The unconventional T cell compartment encompasses a variety of cell subsets that straddle the line between innate and adaptive immunity, often reside at mucosal surfaces and can recognize a wide range of non-polymorphic ligands. Recent advances have highlighted the role of unconventional T cells in tissue homeostasis and disease. In this Review, we recast unconventional T cell subsets according to the class of ligand that they recognize; their expression of semi-invariant or diverse T cell receptors; the structural features that underlie ligand recognition; their acquisition of effector functions in the thymus or periphery; and their distinct functional properties. Unconventional T cells follow specific selection rules and are poised to recognize self or evolutionarily conserved microbial antigens. We discuss these features from an evolutionary perspective to provide insights into the development and function of unconventional T cells. Finally, we elaborate on the functional redundancy of unconventional T cells and their relationship to subsets of innate and adaptive lymphoid cells, and propose that the unconventional T cell compartment has a critical role in our survival by expanding and complementing the role of the conventional T cell compartment in protective immunity, tissue healing and barrier function.

A Comprehensive Analysis of Immune Constituents in Blood and Bronchoalveolar Lavage Allows Identification of an Immune Signature of Severe Asthma in Children

BackgroundTargeted approaches may not account for the complexity of inflammation involved in children with severe asthma (SA), highlighting the need to consider more global analyses. We aimed to identify sets of immune constituents that distinguish children with SA from disease-control subjects through a comprehensive analysis of cells and immune constituents measured in bronchoalveolar lavage (BAL) and blood.MethodsTwenty children with SA and 10 age-matched control subjects with chronic respiratory disorders other than asthma were included. Paired blood and BAL samples were collected and analyzed for a large set of cellular (eosinophils, neutrophils, and subsets of lymphocytes and innate lymphoid cells) and soluble (chemokines, cytokines, and total antibodies) immune constituents. First, correlations of all immune constituents between BAL and blood and with demographic and clinical data were assessed (Spearman correlations). Then, all data were modelled using supervised multivariate analyses (partial least squares discriminant analysis, PLS-DA) to identify immune constituents that significantly discriminate between SA and control subjects. Univariate analyses were performed (Mann-Whitney tests) and then PLS-DA and univariate analyses were combined to identify the most discriminative and significant constituents.ResultsConcentrations of soluble immune constituents poorly correlated between BAL and blood. Certain constituents correlated with age or body mass index and, in asthmatics, with clinical symptoms, such as the number of exacerbations in the previous year, asthma control test score, or forced expiratory volume. Multivariate supervised analysis allowed construction of a model capable of distinguishing children with SA from control subjects with 80% specificity and 100% sensitivity. All immune constituents contributed to the model but some, identified by variable-important-in-projection values > 1 and p < 0.1, contributed more strongly, including BAL Th1 and Th2 cells and eosinophilia, CCL26 (Eotaxin 3), IgA and IL-19 concentrations in blood. Blood concentrations of IL-26, CCL13, APRIL, and Pentraxin-3 may also help in the characterization of SA.ConclusionsThe analysis of a large set of immune constituents may allow the identification of a biological immune signature of SA. Such an approach may provide new leads for delineating the pathogenesis of SA in children and identifying new targets for its diagnosis, prediction, and personalized treatment.