Frequency Of Innate Lymphoid Cells Research Articles

Abstract 2694: The role of innate lymphoid cells and innate like T cells in hepatocellular carcinoma

Abstract The major focus of cancer immunotherapy has been on conventional T cells due to their unique recognition of specific peptide antigens. Despite advances in the cancer immunotherapy field, including the use of atezolizumab and bevacizumab as first-line therapy for unresectable hepatocellular carcinoma (HCC), the overall mortality rate of HCC continues to rise. Innate lymphoid cells (ILC) and innate-like T cells (ILTC) are broadly categorized within the innate lymphoid population as playing an important role in inflammation, tissue repair and immune tolerance. Their ability to react rapidly to stimulants in their local tissue environment as well as to recruit and activate a variety of other immune cells makes these cells attractive targets for anti-tumor therapy. However, previous studies looking at ILCs and ILTCs in cancer have revealed both pro- and anti-tumor functions. Furthermore, the complex interplay between these cell populations in the tumor microenvironment is not well understood, particularly over the natural course of tumor development. In this study, we aim to better elucidate the role of ILC and ILTC populations in HCC progression in terms of both their kinetics and role as potential therapeutic targets. We performed hydrodynamic tail vein injections in mice with two different plasmid combinations to alter expression of commonly mutated oncogenes and tumor suppressors in human HCC (MYC;TP53 and MYC;CTNNB1). Histologic analysis of the livers was performed to determine appropriate time points to assess ILC and ILTC populations. We then designed a comprehensive 29-plex spectral flow panel to assess broad kinetic changes in the frequency of ILC, ILTC, and conventional T cell populations. We show that in early time points (4-7 days post-injection) when neoplastic transformation of hepatocytes has already occurred, mucosal-associated invariant T (MAIT) cells, group 1 ILCs, ILC2s, and ILC3s expand in frequency for both tumor models. Cytokine analysis shows a generalized decreased trend across timepoints in effector cytokine production in MAITs and group 1 ILCs, suggesting gradual dysfunction over time. Taken together, these preliminary findings show that ILC and ILTC populations expand early during tumor progression but gradually decrease in functionality with tumor progression. Citation Format: Patrick Huang, Benjamin Ruf, Rajiv Trehan, Dana Soika, Chi Ma, Tim F. Greten, Firouzeh Korangy. The role of innate lymphoid cells and innate like T cells in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2694.

JAK/STAT inhibition modifies the ILC1 immune response in patients with rheumatoid arthritis.

Recent evidence suggests that innate lymphoid cells (ILCs) might be involved in rheumatoid arthritis (RA) pathogenesis and individuals at risk of RA exhibited an increased frequency of ILC1. JAK3 participates in ILC1 and ILC3 differentiation. Tofacitinib and the Janus Kinase (JAK) 3 inhibitor, PF-06651600, impair the ability of human intraepithelial ILC1 (iILC1) to produce IFN-γ and the proliferation of ILC1 and ILC3. Our study aims to evaluate the ex vivo effects of tofacitinib in RA patients and to investigate if ILC1s and ILC3s are specific targets of tofacitinib in RA. Twenty RA patients starting tofacitinib and 10 RA patients starting anti-TNFα were enrolled. Peripheral blood mononuclear cells (PBMCs) from RA patients, collected before and three months after therapy, were cultured to evaluate ILC1 and ILC3 frequencies and the respective production of IFN-γ and IL-17 by flow cytometry analysis. PBMCs of RA patients were in vitro cultured with tofacitinib to evaluate the dose effects on ILC frequencies. RA patients showed a significant expansion of ILC1 but not ILC3. Unlike anti-TNFα treated patients, in whom no reduction in ILCs was reported, after three months of tofacitinib therapy the overall ILC frequency was reduced, as well as the ILC1 ability to release IFN-γ. In vitro treatment of PBMCs with tofacitinib demonstrated a dose-dependent reduction in the frequency of ILCs compared to untreated cells. Our preliminary results demonstrate that tofacitinib modulates the innate immune response by reducing the frequency of ILC1 cells and their production of IFN-γ.

Contribution of Innate Lymphoid Cells in Supplementing Cytokines Produced by CD4+ T Cells During Acute and Chronic SIV Infection of the Colon.

HIV/SIV (simian immunodeficiency virus) infection leads to a loss of CD4+ T helper (Th) cells in number and function that begins during the acute phase and persists through the chronic phase of infection. In particular, there is a drastic decrease of Th17 and Th22 cells in the HIV/SIV-infected gastrointestinal (GI) tract as a source of interleukin (IL)-17 and IL-22. These cytokines are vital in the immune response to extracellular pathogens and maintenance of the GI tract. However, innate lymphoid cells (ILCs) are a source of IL-17 and IL-22 during the early stages of an immune response in mucosal tissue and remain vital cytokine producers when the immune response is persistent. Here, we wanted to determine whether ILCs are a source of IL-17 and IL-22 in the SIV-infected colon and could compensate for the loss of Th17 and Th22 cells. As a control, we evaluated the frequency and number of ILCs expressing interferon-gamma (IFNγ) and tumor necrosis factor-alpha (TNFα). We determined the frequency and number of cytokine expressing ILC subsets and T cell subsets within leukocytes from the colons of uninfected as well as acute and chronic SIV-infected colons without in vitro mitogenic stimulation. In the present study, we find that: (1) the frequency of IL-22, IFNγ, and TNFα but not IL-17 producing ILCs is increased in the acutely infected colon and remains high during the chronically infected colon relative to cytokine expressing ILCs in the uninfected colon, (2) ILCs are a significant source of IL-22, IFNγ, and TNFα but not IL-17 when CD4+ T lymphocytes in the gut lose their capacity to secrete these cytokines during SIV infection, and (3) the changes in the cytokines expressed by ILCs relative to CD4+ T cells in the infected colon were not due to increases in the frequency or number of ILCs in relation to T lymphocytes found in the tissue.

Innate lymphoid cells in colorectal cancer.

Innate lymphoid cells (ILC) can be viewed as the innate counterparts of T cells. In contrast to T cells, ILCs exert their functions in antigen‐independent manners, relying on tissue‐derived signals from other immune cells, stroma and neurons. Natural killer (NK) cells have been known for their antitumour effects for decades. However, the roles of other ILC subtypes in cancer immunity are just now starting to be unravelled. ILCs contribute to both homeostasis and inflammation in the intestinal mucosa. Intestinal inflammation predisposes the intestine for the development of colonic dysplasia and colorectal cancer (CRC). Recent data from mouse models and human studies indicate that ILCs play a role in CRC, exerting both protumoural and antitumoural functions. Studies also suggest that intratumoural ILC frequencies and expression of ILC signature genes can predict disease progression and response to PD‐1 checkpoint therapy in CRC. In this mini‐review, we focus on such recent insights and their implications for understanding the immunobiology of CRC. We also identify knowledge gaps and research areas that require further work.

Route of Sensitization to Peanut Influences Immune Cell Recruitment at Various Mucosal Sites in Mouse: An Integrative Analysis.

Symptom occurrence at the first ingestion suggests that food allergy may result from earlier sensitization via non-oral routes. We aimed to characterize the cellular populations recruited at various mucosal and immune sites after experimental sensitization though different routes. BALB/cJ mice were exposed to a major allergenic food (peanut) mixed with cholera toxin via the intra-gastric (i.g.), respiratory, cutaneous, or intra-peritoneal (i.p.) route. We assessed sensitization and elicitation of the allergic reaction and frequencies of T cells, innate lymphoid cells (ILC), and inflammatory and dendritic cells (DC) in broncho-alveolar lavages (BAL), lungs, skin, intestine, and various lymph nodes. All cellular data were analyzed through non-supervised and supervised uni/multivariate analysis. All exposure routes, except cutaneous, induced sensitization, but intestinal allergy was induced only in i.g.- and i.p.-exposed mice. Multivariate analysis of all cellular constituents did not discriminate i.g. from control mice. Conversely, respiratory-sensitized mice constituted a distinct cluster, characterized by high local inflammation and immune cells recruitment. Those mice also evidenced changes in ILC frequencies at distant site (intestine). Despite absence of sensitization, cutaneous-exposed mice evidenced comparable changes, albeit less intense. Our study highlights that the initial route of sensitization to a food allergen influences the nature of the immune responses at various mucosal sites. Interconnections of mucosal immune systems may participate in the complexity of clinical manifestations as well as in the atopic march.

Innate lymphoid cell characterization in the rat and their correlation to gut commensal microbes.

Innate lymphoid cells (ILCs) are important for tissue immune homeostasis, and are thoroughly characterized in mice and humans. Here, we have performed in-depth characterization of rat ILCs. Rat ILCs were identified based on differential expression of transcription factors and lack of lineage markers. ILC3s represented the major ILC population of the small intestine, while ILC2s were infrequent but most prominent in liver and adipose tissue. Two major subsets of group 1 ILCs were defined. Lineage- T-bet+ Eomes+ cells were identified as conventional NK cells, while lineage- T-bet+ Eomes- cells were identified as the probable rat counterpart of ILC1s based on their selective expression of the ILC marker CD200R. Rat ILC1s were particularly abundant in liver and intestinal tissues, and were functionally similar to NK cells. Single-cell transcriptomics of spleen and liver cells confirmed the main division of NK cells and ILC1-like cells, and demonstrated Granzyme A as an additional ILC1 marker. We further report differential distributions of NK cells and ILCs along the small and large intestines, and the association of certain bacterial taxa to frequencies of ILCs. In conclusion, we provide a framework for future studies of ILCs in diverse rat experimental models, and novel data on the potential interplay between commensals and intestinal ILCs.

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.

OP13 Mucosal organoids capture Innate Lymphoid Cells (ILC) tissue-specific development and reveal that Inflammatory Bowel Disease-associated ILC modulate intestinal remodelling

Abstract Background Innate Lymphoid Cells (ILC) develop from Common Lymphoid Precursors in the bone marrow, and ILC precursors (ILCP) migrate to mucosa where they mature, promote homeostasis, and provide a potent, antigen-non-specific sources of cytokines. Deciphering what local stimuli drive the final stages of ILCP maturation in these tissues remains a pressing question, as ILC frequencies can become dysregulated during chronic infection and inflammatory diseases. For example, Type-1 innate lymphoid cells (ILC1) are enriched in the mucosa of patients with active inflammatory bowel disease (IBD) and the impact of this accumulation remains elusive. Methods Here, we develop and use co-cultures of both murine and human iPSC-derived gut and lung organoids with ILCP and with mature ILC isolated from IBD patients’ intestinal biopsies. Results Harnessing these versatile models, we demonstrate that epithelial cells provide a complex niche capable of supporting the final maturation of all helper-like ILC1, ILC2, and ILC3. Notably, organoid identity was sufficient to robustly recapitulate tissue-specific ILC imprints and frequencies, even in the absence of microbial stimuli, other cell types, or cytokine supplementation. In addition, we show that that ILC1 drive expansion of the epithelial stem cell crypt through p38γ phosphorylation, driving a potentially pathological proliferative feedback loop between β-catenin and Cd44v6. We harnessed this model to elucidate that this phenotype was unexpectedly regulated by ILC1-derived TGFβ1. We further show that human gut ILC1 also secrete TGFβ1, and drive CD44v6 expression in both HIO epithelium and mesenchyme. As TGFβ1 is a master regulator of fibrosis, the leading indicator for surgery in IBD, we next characterised the ability of ILC1 to regulate matrix remodelling using a functionalized, synthetic hydrogel system. We show that ILC1 drive both matrix stiffening and degradation, which we posit occurs through a balance of MMP9 degradation and TGFβ1-induced fibronectin deposition. Conclusion Taken together, our work provides unprecedented insight into in situ ILC maturation, which we show to be driven by epithelial signals, and into ILC function. We also report that intestinal ILC1 modulate epithelial and matrix remodelling, which may drive either wound healing in homeostasis, but may tip toward pathology when enriched in IBD. Moreover, our work introduces a modular organoid platform, which provides exquisite control over both environmental stimuli and host genetics, making it a powerful tool for dissecting the interactions between complex mucosal tissues and rare cell subtypes in development and disease.

Age-Related Dynamics of Circulating Innate Lymphoid Cells in an African Population

Innate lymphoid cell (ILC) lineages mirror those of CD4+ T helper cell subsets, producing type 1, 2 and 3 cytokines respectively. Studies in adult human populations have shown contributions of non-cytotoxic ILC to immune regulation or pathogenesis in a wide range of diseases and have prompted investigations of potential functional redundancy between ILC and T helper cell compartments in neonates and children. To investigate the potential for ILC to contribute to immune responses across the human lifespan, we examined the numbers and frequencies of peripheral blood ILC subsets in a cohort of Gambians aged between 5 and 73 years of age. ILC2 were the most abundant peripheral blood ILC subset in this Gambian cohort, while ILC1 were the rarest at all ages. Moreover, the frequency of ILC1s (as a proportion of all lymphocytes) was remarkably stable over the life course whereas ILC3 cell frequencies and absolute numbers declined steadily across the life course and ILC2 frequencies and absolute numbers declined from childhood until the age of approx. 30 years of age. Age-related reductions in ILC2 cell numbers appeared to be partially offset by increasing numbers of total and GATA3+ central memory (CD45RA-CCR7+) CD4+ T cells, although there was also a gradual decline in numbers of total and GATA3+ effector memory (CD45RA-CCR7-) CD4+ T cells. Despite reduced overall abundance of ILC2 cells, we observed a coincident increase in the proportion of CD117+ ILC2, indicating potential for age-related adaptation of these cells in childhood and early adulthood. While both CD117+ and CD117- ILC2 cells produced IL-13, these responses occurred predominantly within CD117- cells. Furthermore, comparison of ILC frequencies between aged-matched Gambian and UK young adults (25–29 years) revealed an overall higher proportion of ILC1 and ILC2, but not ILC3 in Gambians. Thus, these data indicate ongoing age-related changes in ILC2 cells throughout life, which retain the capacity to differentiate into potent type 2 cytokine producing cells, consistent with an ongoing role in immune modulation.

Innate lymphoid cells are reduced in pregnant HIV positive women and are associated with preterm birth

Preterm birth is the leading cause of neonatal and child mortality worldwide. Globally, 1.4 million pregnant women are estimated to be living with HIV/AIDS, the majority of whom live in sub-Saharan Africa. Maternal HIV infection and antiretroviral treatment (ART) have been associated with increased rates of preterm birth, but the underlying mechanisms remain unknown. Acute HIV infection is associated with a rapid depletion of all three subsets of innate lymphoid cells (ILCs), ILC1s, ILC2s and ILC3s, which is not reversed by ART. ILCs have been found at the maternal–fetal interface and we therefore investigated the potential association between maternal HIV infection, peripheral ILC frequencies and preterm birth. In our study of pregnant South African women with accurately dated pregnancies, we show that maternal HIV infection is associated with reduced levels of all three ILC subsets. Preterm birth was also associated with lower levels of all three ILC subsets in early pregnancy. ILC frequencies were lowest in HIV positive women who experienced preterm birth. Moreover, ILC levels were reduced in pregnancies resulting in spontaneous onset of preterm labour and in extreme preterm birth (< 28 weeks gestation). Our findings suggest that reduced ILC frequencies may be a link between maternal HIV infection and preterm birth. In addition, ILC frequencies in early pregnancy may serve as predictive biomarkers for women who are at risk of delivering preterm.

Graft Versus Host Disease Leads to Elimination of Tissue-Resident Innate Lymphoid Cells Following Experimental and Clinical Allogeneic Transplantation

A potential role for endogenous innate lymphoid cells (ILCs) in prevention of gastrointestinal (GI) GVHD has recently been described in murine and clinical models, and experimental approaches for adoptive cellular therapy with ILCs have recently been described as well. However, the specific in vivo roles of tissue-resident ILCs and their capacity for reconstitution post-transplant remain unclear. We thus sought to characterize the significance and tissue distribution of ILCs after allogeneic bone marrow transplant (allo-BMT) in mouse models and in patients. In order to specifically assess the functional role of ILCs after allo-BMT, we established a clinically relevant acute GVHD model based on sex mismatched H-Y antigens. Lethally irradiated Rag2-/-male mice (Thy1.2, B6) were transplanted with T cell-depleted (TCD) BM and purified T cells obtained from wild-type female mice (Thy1.1, B6). To specifically deplete host-derived ILCs (and not donor cells), recipient mice were treated with an anti-Thy1.2 antibody or an anti-isotype antibody prior to BMT. Pre-transplant depletion of ILCs induced significantly worse systemic signs of GVHD, as well as increased thymic injury and intestinal GVHD pathology, indicating an important role for endogenous ILCs in tissue protection after allo-BMT in this context. To better understand the roles of tissue-resident ILCs in reducing pathology post-BMT, we evaluated ILC subsets in different GVHD target organs after allo-BMT. Two weeks after MHC-mismatched (C57BL6 into BALB/c) TCD-BMT, both donor- and host-derived ILCs could be detected in the liver, lungs, and intestines. Liver was characterized by a high number of NK cells and ILC1s, while lungs contained a high proportion of ILC2s. The small intestine contained a relatively greater proportion of ILC3s. For all tissues analyzed, the majority of ILCs were host-derived. During T cell replete BMT resulting in GVHD, both donor and host-derived ILCs were significantly reduced in all three tissues compared to TCD-BMT mice, and this was true for all ILC lineages. To better understand the loss of donor-derived ILCs in GVHD, we investigated ILC precursors in recipient marrow post-BMT, hypothesizing that an impairment of ILC precursors could explain the loss of all ILC lineages in the various tissues analyzed. Indeed, we found a significant loss of CLPs, αLPs, CHILPs, and ILC2Ps in mice with GVHD, suggesting that bone marrow involvement with GVHD induced a loss of ILC precursors impairing their reconstitution. We next sought to evaluate if the loss of tissue-resident ILCs in GVHD target organs after experimental BMT was relevant for clinical transplantation. To evaluate ILC frequencies in patient tissues post-transplant, duodenal biopsies were collected from patients undergoing clinically indicated endoscopy to work up symptoms of acute upper GI (UGI) GVHD. In total, duodenal samples were collected from ten patients post-transplant and 6/10 had histologic evidence of GVHD on biopsy (Table 1). While frequencies were low, ILCs could be identified by FACS in digested lamina propria of duodenal biopsy specimens. Notably, ILC frequencies were significantly lower in patients with biopsy-proven UGI GVHD, and duodenal ILCs could be identified in only 1/6 patients with histologic evidence of GVHD (Fig 1). Among the ILCs that could be identified, ILC1s represented the greatest proportion of ILC populations within the duodenal lamina propria. Accordingly, the frequency of ILC1s was significantly reduced in transplant patients with biopsy-proven UGI GVHD. Additionally, we were able to evaluate paired peripheral blood and duodenal biopsy samples in a small subset of patients. Although the numbers were limiting, this cohort suggested that ILC2s may represent a greater proportion of ILCs in peripheral blood than in the duodenum post-transplant. Overall, clinical findings were consistent with experimental models demonstrating a reduction of ILCs in GVHD. In conclusion, tissue-resident ILCs contribute to tissue protection after allo-BMT, but GVHD leads to elimination of pre-existing ILCs and loss of ILC precursors in the marrow, impairing their reconstitution. Most duodenal ILCs in clinical biopsy samples post-transplant were ILC1s in this patient cohort, and patients with biopsy-proven UGI GVHD demonstrated significant loss of the few lamina propria ILCs that could be identified in clinical duodenal biopsies. Disclosures Hanash: Nexus Global Group LLC: Consultancy.

Differential Effect of Mucosal NKp44+ Innate Lymphoid Cells and Δγ Cells on Simian Immunodeficiency Virus Infection Outcome in Rhesus Macaques.

NK cells are essential for controlling viral infections. We investigated NK cell and innate lymphoid cell (ILC) dynamics and function in rhesus macaque rectal tissue and blood following mucosal priming with replicating adenovirus (Ad)-SIV recombinants, systemic boosting with SIV envelope protein, and subsequent repeated low-dose intravaginal SIV exposures. Mucosal memory-like NK and ILC subsets in rectal and vaginal tissues of chronically infected macaques were also evaluated. No differences in NK cell or ILC frequencies or cytokine production were seen between vaccinated and Ad-empty/alum controls, suggesting responses were due to the Ad-vector and alum vaccine components. Mucosal NKp44+ ILCs increased postvaccination and returned to prelevels postinfection. The vaccine regimen induced mucosal SIV-specific Ab, which mediated Ab-dependent cellular cytotoxicity and was correlated with mucosal NKp44+CD16+ ILCs. Postvaccination NKp44+ and NKp44+IL-17+ ILC frequencies were associated with delayed SIV acquisition and decreased viremia. In chronically SIV-infected animals, NKp44+ ILCs negatively correlated with viral load, further suggesting a protective effect, whereas, NKG2A- NKp44- double-negative ILCs positively correlated with viral load, indicating a pathogenic role. No such associations of circulating NK cells were seen. Δγ NK cells in mucosal tissues of chronically infected animals exhibited impaired cytokine production compared with non-Δγ NK cells but responded to anti-gp120 Ab and Gag peptides, whereas non-Δγ NK cells did not. Mucosal Δγ NKp44+ and Δγ DN cells were similarly associated with protection and disease progression, respectively. Thus, the data suggest NKp44+ ILCs and Δγ cells contribute to SIV infection outcomes. Vaccines that promote mucosal NKp44+ and suppress double-negative ILCs are likely desirable.

Hallmarks of primate lentiviral immunodeficiency infection recapitulate loss of innate lymphoid cells

Innate lymphoid cells (ILCs) play critical roles in mucosal barrier defense and tissue homeostasis. While ILCs are depleted in HIV-1 infection, this phenomenon is not a generalized feature of all viral infections. Here we show in untreated SIV-infected rhesus macaques (RMs) that ILC3s are lost rapidly in mesenteric lymph nodes (MLNs), yet preserved in SIV+ RMs with pharmacologic or natural control of viremia. In healthy uninfected RMs, experimental depletion of CD4+ T cells in combination with dextran sodium sulfate (DSS) is sufficient to reduce ILC frequencies in the MLN. In this setting and in chronic SIV+ RMs, IL-7Rα chain expression diminishes on ILC3s in contrast to the IL-18Rα chain expression which remains stable. In HIV-uninfected patients with durable CD4+ T cell deficiency (deemed idiopathic CD4+ lymphopenia), similar ILC deficiencies in blood were observed, collectively identifying determinants of ILC homeostasis in primates and potential mechanisms underlying their depletion in HIV/SIV infection.

Abstract B62: Immune gene expression profiling identifies predictors of relapse in childhood acute myeloid leukemia

Abstract Tumor phenotypes are dictated not only by the neoplastic cell component, but also by the tumor microenvironment (TME), which includes immune and inflammatory cells. Acute myeloid leukemia (AML) is the second most common leukemia of childhood. Although intensive multi-agent chemotherapy in conjunction with improved supportive care has increased survival rates to 70%, 30-40% of children with AML relapse and only one-third of them will survive to adulthood. Investigation of new therapeutic strategies for high-risk AML, including immunotherapy, remains a priority and is being actively pursued. Importantly, AML-induced immune suppression poses a fundamental barrier to successful immune-based interventions. We previously showed that in vitro treatment of primary AML cells with interferon (IFN)-γ induces functional indoleamine 2,3-dioxygenase-1 (IDO1), a molecule with potent immunosuppressive properties, in 50% of unselected cases (IFN-γ responders). With a median follow-up of 8 years, IFN-γ responders experienced a significantly shorter event-free survival and overall survival (OS). Herein, we aimed to get insights into the immune landscape of childhood AML using multi-scale immune profiling strategies with the aim to identify molecular circuits that can be targeted to revert leukemia-induced immune dysfunction and improve clinical outcome. We employed a novel high-throughput digital platform, the nCounter system (nanoString Technologies, Seattle, USA), and Optimized Multi-color Immuno-phenotyping Panels (OMIPs) to comprehensively characterize the bone marrow immune infiltrate in 34 children diagnosed with non-promyelocytic AML (17 males, 17 females; median age at diagnosis=10 years; 28 de novo AML, 4 infant leukemia, 1 secondary AML, 1 congenital leukemia; 7 patients with favorable-risk cytogenetics, 21 patients with intermediate-risk cytogenetics and 6 patients with unfavorable-risk cytogenetics). The RNA Pan-Cancer Immune Profiling Panel, which includes 109 cell surface markers for 24 immune cell types, 30 cancer testis antigens, and &amp;gt;500 immune response genes, allowed us to measure immune gene expression levels on the clinic-ready nCounter® FLEX platform (nanoString Technologies). Transcriptomic data were normalized and analyzed using the nSolver software package. Relapse-free survival (RFS) and OS were selected as covariates. For immune phenotyping studies, viable bone marrow mononuclear cells were labeled with fluorochrome-conjugated antibodies and then analyzed on a 10-color Gallios flow cytometer (Beckman Coulter Life Sciences, Buckinghamshire, UK) with standard settings. Hierarchical clustering of immune gene expression data highlighted patient subgroups with heightened expression of T-cell and natural killer (NK)-cell function genes, as well as Toll-like receptor (TLR) genes, interleukin genes and tumor necrosis factor (TNF) family genes. Patients with high levels of CD8A mRNA also expressed IFNG, CXCL9, CXCL10, FOXP3 and negative checkpoints, including LAG3, CTLA4, IDO1 and CD279 (PD-L1), consistent with T-cell inflamed phenotypes that might underpin the establishment of adaptive immune resistance mechanisms of immune escape. In-depth phenotyping studies showed higher percentages of bone marrow-resident naïve B cells, plasmablasts, intermediate and non-conventional monocytes, plasmacytoid dendritic cells (DCs) and CXCR3-expressing Th1 cells at diagnosis compared with complete remission (CR). By contrast, both type 1 and type 2 myeloid DCs were more represented in the TME of patients with AML in CR. The frequencies of innate lymphoid cells (ILCs) and Vγ9+Vδ2+ T cells were not significantly different when comparing diagnosis and CR samples. Relapses occurred in 71.4% of children with “inflamed” AML compared with 28.6% of patients with “non-inflamed” AML (p=0.012; two-sided Fisher’s exact test). Importantly, RFS was remarkably shorter in patients with inflamed compared with non-inflamed AML (median RFS=394 days vs. undefined; hazard ratio = 0.266; 95% CI=0.11-0.64; p=0.0039, log-rank test). A non-significant association with OS was also observed. In conclusion, inflamed or “hot” AMLs are associated with shorter RFS and might be amenable to immunotherapy approaches tailored to the bone marrow TME, including PD-1/PD-L1 blockade and/or small-molecule IDO1 inhibitors. Grant support: Roger Counter Foundation, Dorset, UK and Qatar National Research Fund (grant #NPRP8-2297-3-494). Citation Format: Jayakumar Vadakekolathu, Gemma A. Foulds, Tasleema Patel, Stephen Reeder, Alan Graham Pockley, Sarah K. Tasian, Sergio Rutella. Immune gene expression profiling identifies predictors of relapse in childhood acute myeloid leukemia [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr B62.

Isolation of Human Innate Lymphoid Cells.

Innate lymphoid cells (ILCs) are innate immune cells of lymphoid origin that have important effector and regulatory functions in the first line of defense against pathogens, but also regulate tissue homeostasis, remodeling, and repair. Their function mirrors T helper cells and cytotoxic CD8+ T lymphocytes, but they lack expression of rearranged antigen-specific receptors. Distinct ILC subsets are classified in group 1 ILCs (ILC1s), group 2 ILCs (ILC2s), and group 3 ILCs (ILC3s and lymphoid tissue-inducer cells), based on the expression of transcription factors and the cytokines they produce. As the frequency of ILCs is low, their isolation requires extensive depletion of other cell types. The lack of unique cell surface antigens further complicates the identification of these cells. Here, methods for ILC isolation and characterization from human peripheral blood and different tissues are described. © 2018 by John Wiley & Sons, Inc.

CHARACTERIZATION OF INTERLEUKIN-17 PRODUCING CELLS IN THE PERIPHERAL BLOOD OF PATIENTS WITH TUBERCULOSIS

Abstract Tuberculosis (TB), an infection caused by Mycobacterium tuberculosis, is one of the ten main causes of death by infectious disease. When the mycobacteria are inhaled, they interact with immune cells in the respiratory tract in a specialized structure known as granuloma. Interleukin 17 (IL-17) contributes to formation and size of the granuloma, and it correlates with the recruitment of neutrophils. It has been demonstrated that other innate lymphocytes, such as Tγδ cells, contribute to the production of IL-17 during TB. Innate lymphoid cells (ILCs) are other innate lymphocytes that are classified into groups (ILC1, ILC2 and ILC3) according to their cytokine patterns. ILC3 produce IL-17, but it is not known if these cells participate in the response to TB infection. We evaluated, by flow cytometry, the frequency and IL-17 production of Th, Tgd, NK and ILCs (ILC1, ILC2 and ILC3) in the peripheral blood of healthy individuals (negative and positive for the Quantiferon [QTF] test, which detects latent TB), and of patients with active pulmonary TB. The numbers of Th cells, NK cells and ILCs (ILC1, ILC2 and ILC3) were decreased in TB patients, compared to healthy individuals. Peripheral blood was stimulated with M. tuberculosis soluble extract (MTSE) for 5 h in the presence of brefeldin A. After stimulation, Th cells from QTF-positive healthy individuals and TB patients produced IL-17. Tγδ cells also produced IL-17, although the percentage of these cells did not change after activation with MTSE. In some cases, NK, ILC2 and ILC3 from TB patients produced IL-17, but this production did not change after MTSE activation. These results indicate that Th and Tγδ cells contribute to IL-17 production during TB. This project was funded by SIP-IPN-México (20180254).

Brief Report: Inflammatory Colonic Innate Lymphoid Cells Are Increased During Untreated HIV-1 Infection and Associated With Markers of Gut Dysbiosis and Mucosal Immune Activation.

HIV-1 infection is associated with intestinal inflammation, changes in the enteric microbiota (dysbiosis), and intestinal epithelial cell damage. NKp44 innate lymphoid cells (ILCs) play an important role in epithelial barrier maintenance through the production of interleukin (IL)-22 but also display functional plasticity and can produce inflammatory cytokines [eg, interferon gamma (IFNγ)] in response to cytokine milieu and stimulatory signals. The objective of this pilot study was to enumerate frequencies of IL-22 and IFNγ-expressing colonic NKp44 ILCs during untreated, chronic HIV-1 infection. A cross-sectional study was performed to compare numbers of cytokine-expressing ILCs in colonic biopsies of untreated, chronic HIV-1 infected (n = 22), and uninfected (n = 10) study participants. Associations between cytokine ILC and previously established measures of virological, immunological, and microbiome indices were analyzed. Multicolor flow cytometry was used to measure the absolute number of colonic CD3NKp44CD56 ILCs expressing IL-22 or IFNγ after in vitro mitogenic stimulation. Numbers of colonic NKp44 ILCs that expressed IFNγ were significantly higher in HIV-1 infected versus uninfected persons and positively correlated with relative abundances of dysbiotic bacterial species in the Xanthomonadaceae and Prevotellaceae bacterial families and with colonic myeloid dendritic cell and T-cell activation. Higher numbers of inflammatory colonic ILCs during untreated chronic HIV-1 infection that associated with dysbiosis and colonic myeloid dendritic cell and T-cell activation suggest that inflammatory ILCs may contribute to gut mucosal inflammation and epithelial barrier breakdown, important features of HIV-1 mucosal pathogenesis.

CHARACTERIZATION OF INTERFERON-γ PRODUCING CELLS IN THE PERIPHERAL BLOOD OF PATIENTS WITH TUBERCULOSIS

Abstract Tuberculosis (TB) caused 1.4 million deaths in 2015. The infection starts when Mycobacterium tuberculosis is inhaled and interacts with immune cells in the respiratory tract. Alveolar macrophages, neutrophils and dendritic cells (DCs) engulf the mycobacteria; these DCs migrate to the draining lymph node and induce the activation of mycobacteria-specific Th cells. These Th cells migrate back to the lung and produce IFNγ and TNFα, two cytokines essential for mycobacterial control. In addition to Th cells, other cells, such as Tγδ and NK cells, produce IFNγ in response to mycobacteria; innate lymphoid cells (ILCs) are also able to produce IFNγ, but it still unknown if ILCs, which have been detected in human lungs during cancer, produce this cytokine in response to mycobacteria. We evaluated, by flow cytometry, the frequency and IFNγ production of Th, Tγδ, NK and ILCs (ILC1, ILC2 and ILC3) in the peripheral blood of healthy individuals (negative and positive for the Quantiferon [QTF] test, which detects latent TB), and patients with active pulmonary TB. The numbers of Th, Tγδ, NK cells and ILCs (ILC1, ILC2 and ILC3) were decreased in TB patients. Peripheral blood was stimulated with M. tuberculosis soluble extract for 5 h in the presence of brefeldin A. In healthy, QTF-negative individuals, IFNγ production was increased in Tγδ and ILC2 after stimulation; in healthy, QTF-positive individuals, IFNγ production was increased in Th, Tγδ and ILCs, and in TB patients, IFNγ production was increased in NK cells and ILC2. These results suggest ILCs produce IFNγ during TB infection. This project was funded by SIP-IPN-México (20170616).

Innate lymphoid cells (ILCs) from septic patients produce higher levels of cytokines than ILCs from healthy controls

Abstract Sepsis is a systemic inflammatory response to infection, which leads to life-threatening organ dysfunction. During sepsis, many cells of the innate and adaptive immune systems have functional alterations; in particular, monocytes produce reduced levels of pro-inflammatory cytokines in response to microbial products (MAMPs). Innate lymphoid cells (ILCs) are cells with lymphocyte morphology that lack antigen-specific receptors and respond directly to cytokines and MAMPs; it is not known if ILCs are affected during sepsis. In this study, we used flow cytometry to evaluate the frequency of ILCs in the peripheral blood of septic patients and healthy controls, as well as the expression of CD56, CCR6 and NKp44 and the production of IL-17 and IFN-γ by ILCs. ILCs were defined as CD45+ lineage- CD127+ cells. The number of total lymphocytes and the number of ILCs were significantly lower in septic patients, compared to healthy controls, with ILCs representing around 0.5% of peripheral blood lymphocytes. In both healthy controls and septic patients, CD56 defines two populations of ILCs: a higher percentage of the CD56− cells express CCR6, compared to the CD56+ cells, while a higher percentage of the CD56+ cells express NKp44, compared to the CD56− cells. CD56− ILCs are the main producers of IL-17, while CD56+ cells are the main producers of IFN-γ, in both healthy controls and septic patients. The production of these two cytokines is increased in the ILCs from septic patients, compared to the ILCs from healthy controls. This is in contrast with the decreased cytokine production that is observed in monocytes and T lymphocytes from septic patients. This project was funded by CONACyT-México (219661).

Functional Defects in Type 3 Innate Lymphoid Cells and Classical Monocytes in a Patient with Hyper-IgE Syndrome

Hyper-IgE syndrome (HIES) is a very rare primary immune deficiency characterized by elevated serum IgE levels, recurrent bacterial infections, chronic dermatitis, and connective tissue abnormalities. Autosomal dominant (AD) HIES involves a mutation in signal transducer and activator of transcription 3 (STAT3) that leads to an impaired TH17 response. STAT3 signaling is also involved in the function of RORγt+ type 3 innate lymphoid cells (ILC3s) and RORγt+TH17 cells. The aim of this study was to investigate the role of innate immune cells such as innate lymphoid cells (ILCs), granulocytes, and monocytes in a patient with HIES. Peripheral blood mononuclear cells (PBMCs) from a patient with HIES and three age-matched healthy controls were obtained for the analysis of the innate and adaptive immune cells. The frequencies of ILCs in PBMCs were lower in the patient with HIES than in the controls. Moreover, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-17A produced by ILC3s in PBMCs were lower in the patient with HIES than the controls. Compared with the controls, classical monocytes (CD14+CD16low), which have a high antimicrobial capability, were also lower in the patient with HIES, while non-classical monocytes (CD14lowCD16+) as well as intermediate monocytes (CD14+CD16intermediate) were higher. Taken together, these results indicate that the impaired immune defense against pathogenic microbes in the patient with HIES might be partially explained by functional defects in ILC3s and inflammatory monocytes.