Natural Killer Cell Function Research Articles

180P FIRE-6: Longitudinal immune profiling identified disturbed NK cell functionality in RAS/BRAF wild-type metastatic colorectal cancer patients and during combined treatment with FOLFIRI, cetuximab followed by avelumab maintenance

180P FIRE-6: Longitudinal immune profiling identified disturbed NK cell functionality in RAS/BRAF wild-type metastatic colorectal cancer patients and during combined treatment with FOLFIRI, cetuximab followed by avelumab maintenance

Sepsis induced dysfunction of liver type 1 innate lymphoid cells

BackgroundSepsis is a life-threatening condition triggered by uncontrolled immune responses to infection, leading to widespread inflammation, tissue damage, organ dysfunction, and potentially death. The liver plays a crucial role in the immune response during sepsis, serving as a major site for immune cell activation and cytokine production. Liver type 1 innate lymphoid cells (ILCs) consist of NK cells and ILC1s. They maintain the local immune microenvironment by directly eliminating target cells and secreting cytokines. However, the specific roles and pathological changes of liver-resident NK cells and ILC1s during sepsis remain poorly understood.ResultsThis study aims to investigate the pathological changes of NK cells and ILC1s, which might contribute the dysfunction of liver. Sepsis mouse model was established by cecal ligation and puncture (CLP). Mouse immune cells from liver were isolated, and the surface makers, gene expression profiles, cytokine response and secretion, and mitochondrial function of NK (Natural Killer) cells and ILC1s (Innate Lymphoid Cell 1) were analyzed. A significant decrease in the number of mature NK cells was observed in the liver after CLP. Furthermore, the secretion of interferon-gamma (IFN-γ) was found to be reduced in spleen and liver NK cells when stimulated by IL-18. Mitochondrial activities in both liver NK cells and ILC1 were found to be increased during sepsis, suggesting an enhanced metabolic response in these cells to combat the infection. However, despite this heightened activity, liver NK cells exhibited a decreased level of cytotoxicity, which might impact their ability to target infected cells effectively. RNA sequencing supported and provided the potential mechanisms for the proinflammatory effects and exhaustion like phenotypes of liver NK cells.ConclusionsSepsis induces dysfunction and exhaustion-like phenotypes in liver NK cells and ILC1, which might further impair other immune cells and represent a potential therapeutic target for sepsis.

Research Advances on Natural Killer Cells in Infections

Natural killer (NK) cells play a crucial role in the human immune system, swiftly recognizing and eliminating infected cells through non-specific immune mechanisms. This paper reviews the mechanisms by which NK cells act in various infections, including those caused by viruses, bacteria, parasites, and fungi, and explores their biological characteristics and functional regulation in the context of infection. By thoroughly analyzing the regulatory mechanisms of cytokines, receptor-ligand interactions, and the microenvironment on NK cell function, this paper further elucidates the response mechanisms of NK cells under different infection scenarios. Finally, it discusses the clinical application prospects of NK cells in treating infectious diseases and outlines future research directions, providing new ideas and possibilities for NK cell-based immunotherapy strategies.

Harnessing the Power of NK Cell Receptor Engineering as a New Prospect in Cancer Immunotherapy.

Natural killer (NK) cells have recently gained popularity as an alternative for cancer immunotherapy. Adoptive cell transfer employing NK cells offers a safer therapeutic option compared to T-cell-based therapies, due to their significantly lower toxicity and the availability of diverse autologous and allogeneic NK cell sources. However, several challenges are associated with NK cell therapies, including limited in vivo persistence, the immunosuppressive and hostile tumor microenvironment (TME), and the lack of effective treatments for solid tumors. To address these limitations, the modification of NK cells to stably produce cytokines has been proposed as a strategy to enhance their persistence and proliferation. Additionally, the overexpression of activating receptors and the blockade of inhibitory receptors can restore the NK cell functions hindered by the TME. To further improve tumor infiltration and the elimination of solid tumors, innovative approaches focusing on the enhancement of NK cell chemotaxis through the overexpression of chemotactic receptors have been introduced. This review highlights the latest advancements in preclinical and clinical studies investigating the engineering of activating, inhibitory, and chemotactic NK cell receptors; discusses recent progress in cytokine manipulation; and explores the potential of combining the chimeric antigen receptor (CAR) technology with NK cell receptors engineering.

The Role of Spinal Anaesthesia with and without Intrathecal Opioid Coadministration in Improving Oncologic Outcomes after Endoscopic Transurethral Cancer Surgery

Spinal anaesthesia (SA) (compared to general) improves postoperative oncologic outcomes in transurethral resection of the bladder tumour (TURBT) for non-muscle invasive bladder cancer (NMIBC). Intrathecal coadministration of opioids does not affect NK cells function, and improves postoperative opioid sparing as well. There are no comparative data on oncologic outcomes of SA with/without intrathecal opioid in TURBT, which is the aim of our study. Seventy ASA I-III patients with NMIBC, aged ≥ 43 (range 43-90), who underwent one or more TURBT under SA were examined retrospectively. Of them, 36 received levobupivacaine 15 mg (L group) and 34 levobupivacaine 12.5 mg + fentanyl 12.5 mcg (LF group) intrathecally. All patients received scheduled Paracetamol 1.0 g/6 h, optional NSAIDs and as needed Tramadol as well. Data regarding demographics, ASA and CCI scores, analgesics consumption, urethrotomies, tumour-related factors (size, number, grade, stage, prior disease-recurrence, adjuvant therapy), tumour risk (low, intermediate, high), oncologic outcomes (recurrence rate/free time after TURB during the regular cystoscopy every 3 months/first year, every six months thereafter) were explored as well. LF patients were older, with less analgesics consumption and with a tendency towards longer recurrence-free time compared to L patients (p=0.074). The recurrence at three months along with prior and new disease-recurrences comprise our minority (n=27) with aggressive course of the disease. Among the rest the majority, LF subgroup (n=19) had lower recurrence rate than L subgroup (n=24) (p=0.03). As part of multimodal analgesic strategy, SA with intrathecal opioid coadministration may play a significant complementary role regarding oncologic outcomes after TURBT for NMIBC.

In-Depth Analysis of the Peripheral Immune Profile of HER2+ Breast Cancer Patients on Neoadjuvant Treatment with Chemotherapy Plus Trastuzumab Plus Pertuzumab.

Currently, therapy for early-stage human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC) is based on the combination of trastuzumab and pertuzumab plus chemotherapy in a neoadjuvant regimen. The INMUNOHER study aimed to detect immunological markers in peripheral blood and their association with treatment response. Sixty-two HER2+ BC patients were recruited. Pre-treatment samples were obtained before the start of treatment, while post-treatment samples were obtained after completing therapy and before surgery and were analyzed by flow cytometry. The pathologic complete response (pCR) rate achieved was 82.3%. The expression of the NKp30, PD-1, and TIM-3 receptors was reduced in the Natural Killer (NK)-CD56dim subset of patients who did not achieve pCR. Following therapy, many changes were found in leukocytes, including alterations in T cell lymphocyte proportions. Also, the percentage of NK cells decreased, and several phenotypic changes were observed in this population. After treatment, IFN-γ production by NK cells against HER2+-cells with or without trastuzumab was significantly reduced. HER2-targeted therapy plus chemotherapy demonstrated high efficacy in most patients, reducing the statistical power for finding immunological markers. However, NK subset phenotypes correlated better with response groups, and numerous changes in the percentage of leukocytes and T and NK cells, as well as changes in the functionality of NK cells, were observed in most patients after treatment, encouraging further research into these immune populations.

Polygenic polymorphism is associated with NKG2A repertoire and influences lymphocyte phenotype and function

AbstractCD94/NKG2A is a heterodimeric receptor commonly found on natural killer (NK) and T cells, and its interaction with its ligand HLA-E on adjacent cells leads to inhibitory signaling and cell suppression. We have identified several killer cell lectin–like receptor (KLR)C1 (NKG2A) single nucleotide polymorphisms (SNPs) that are associated with NKG2A expression on NK cells, CD8+ T cells, and Vγ9/Vδ2+ T cells. Additionally, due to strong linkage disequilibrium, polymorphisms in KLRC2 (NKG2C) and KLRK1 (NKG2D) are also associated with NKG2A surface density and frequency. NKG2A surface expression correlates with single-cell NK responsiveness, and NKG2A+ NK cell frequency is associated with total NK repertoire response and inhibitability, making the identification of SNPs responsible for expression and frequency important for predicting the innate immune response. Because HLA-E expression is dependent on HLA class I signal peptides, we analyzed the relationship between peptide abundance and HLA-E expression levels. Our findings revealed a strong association between peptide availability and HLA-E expression. We identified the HLA-C killer immunoglobulin–like receptor ligand epitope as a predictive marker for HLA-ABC expression, with the HLA-C1 epitope associated with high HLA-E expression and the HLA-C2 epitope associated with low HLA-E expression. The relationship between HLA-C epitopes and HLA-E expression was independent of HLA-E allotypes and HLA-B leader peptides. Although HLA-E expression showed no significant influence on NKG2A-mediated NK education, it did affect NK cell inhibition. In summary, these findings underscore the importance of NKG2A SNPs and HLA-C epitopes as predictive markers of NK cell phenotype and function and should be evaluated as prognostic markers for diseases that express high levels of HLA-E.

Biologically-informed Killer cell immunoglobulin-like receptor (KIR) gene annotation tool.

Natural killer (NK) cells are essential components of the innate immune system, with their activity significantly regulated by Killer cell Immunoglobulin-like Receptors (KIRs). The diversity and structural complexity of KIR genes present significant challenges for accurate genotyping, essential for understanding NK cell functions and their implications in health and disease. Traditional genotyping methods struggle with the variable nature of KIR genes, leading to inaccuracies that can impede immunogenetic research. These challenges extend to high-quality phased assemblies, which have been recently popularized by the Human Pangenome Consortium. This paper introduces BAKIR (Biologically-informed Annotator for KIR locus), a tailored computational tool designed to overcome the challenges of KIR genotyping and annotation on high-quality, phased genome assemblies. BAKIR aims to enhance the accuracy of KIR gene annotations by structuring its annotation pipeline around identifying key functional mutations, thereby improving the identification and subsequent relevance of gene and allele calls. It uses a multi-stage mapping, alignment, and variant calling process to ensure high-precision gene and allele identification, while also maintaining high recall for sequences that are significantly mutated or truncated relative to the known allele database. BAKIR has been evaluated on a subset of the HPRC assemblies, where BAKIR was able to improve many of the associated annotations and call novel variants. BAKIR is freely available on GitHub, offering ease of access and use through multiple installation methods, including pip, conda, and singularity container, and is equipped with a user-friendly command-line interface, thereby promoting its adoption in the scientific community.

A role of gut microbiota metabolites in HLA-E and NKG2 blockage immunotherapy against tumors: new insights for clinical application.

One of major breakthroughs in immunotherapy against tumor is from blocking immune checkpoint molecules on tumor and reactive T cells. The development of CTLA-4 and PD-1 blockage antibodies has triggered to search for additional effective therapeutic strategies. This causes recent findings that blocking the interaction of checkpoint molecule NKG2A in NK and CD8 T cells with HLA-E in tumors is effective in defensing tumors. Interestingly, gut microbiota also affects this immune checkpoint immunotherapy against tumor. Gut microbiota such as bacteria can contribute to the regulation of host immune response and homeostasis. They not only promote the differentiation and function of immunosuppressive cells but also the inflammatory cells through the metabolites such as tryptophan (Trp) and bile acid (BA) metabolites as well as short chain fatty acids (SCFAs). These gut microbiota metabolites (GMMs) educated immune cells can affect the differentiation and function of effective CD8 and NK cells. Notably, these metabolites also directly affect the activity of CD8 and NK cells. Furthermore, the expression of CD94/NKG2A in the immune cells and/or their ligand HLA-E in the tumor cells is also regulated by gut microbiota associated immune factors. These findings offer new insights for the clinical application of gut microbiota in precise and/or personalized treatments of tumors. In this review, we will discuss the impacts of GMMs and GMM educated immune cells on the activity of effective CD8 and NK cells and the expression of CD94/NKG2A in immune cells and/or their ligand HLA-E in tumor cells.

Potential role of B- and NK-cells in the pathogenesis of pediatric aplastic anemia through deep phenotyping.

Pediatric patients with unexplained bone marrow failure (BMF) are often categorized as aplastic anemia (AA). Based on the accepted hypothesis of an auto-immune mechanism underlying AA, immune suppressive therapy (IST) might be effective. However, due to the lack of diagnostic tools to identify immune AA and prognostic markers to predict IST response together with the unequaled curative potential of hematopoietic stem cell transplantation (HSCT), most pediatric severe AA patients are momentarily treated by HSCT if available. Although several studies indicate oligoclonal T-cells with cytotoxic activities towards the hematopoietic stem cells, increasing evidence points towards defective inhibitory mechanisms failing to inhibit auto-reactive T-cells. We aimed to investigate the role of NK- and B-cells in seven pediatric AA patients through a comprehensive analysis of paired bone marrow and peripheral blood samples with spectral flow cytometry in comparison to healthy age-matched bone marrow donors. We observed a reduced absolute number of NK-cells in peripheral blood of AA patients with a skewed distribution towards CD56bright NK-cells in a subgroup of patients. The enriched CD56bright NK-cells had a lower expression of CD45RA and TIGIT and a higher expression of CD16, compared to healthy donors. Functional analysis revealed no differences in degranulation. However, IFN-γ production and perforin expression of NK-cells were reduced in the CD56bright-enriched patient group. The diminished NK-cell function in this subgroup might underly the auto-immunity. Importantly, NK-function of AA patients with reduced CD56bright NK-cells was comparable to healthy donors. Also, B-cell counts were lower in AA patients. Subset analysis revealed a trend towards reduction of transitional B-cells in both absolute and relative numbers compared to healthy controls. As these cells were previously hypothesized as regulatory cells in AA, decreased numbers might be involved in defective inhibition of auto-reactive T-cells. Interestingly, even in patients with normal distribution of precursor B-cells, the transitional compartment was reduced, indicating partial differentiation failure from immature to transitional B-cells or a selective loss. Our findings provide a base for future studies to unravel the role of transitional B-cells and CD56bright NK-cells in larger cohorts of pediatric AA patients as diagnostic markers for immune AA and targets for therapeutic interventions.

Prognostic impact of enhanced CD96 expression on NK cells by TGF-β1 in AML

Acute myeloid leukemia (AML) is one of the most common types of blood cancer in adults and is associated with a poor survival rate. NK cells play a crucial role in combating AML, and alterations in immune checkpoint expression can impair NK cell function against AML. Targeting certain checkpoints may restore this function. CD96, an inhibitory immune checkpoint, has unclear expression and roles on NK cells in AML patients. In this study, we initially evaluated CD96 expression and compared CD96+ NK with the inhibitory receptor and stimulatory receptors on NK cells from AML patients at initial diagnosis. We observed increased CD96 expression on NK cells with dysfunctional phenotype. Further analysis revealed that CD96+ NK cells had lower IFN-γ production than CD96- NK cells. Blocking CD96 enhanced the cytotoxicity of primary NK and cord blood-derived NK (CB-NK) cells against leukemia cells. Notably, patients with a high frequency of CD96+ NK cells at initial diagnosis exhibited poorer clinical outcomes. Additionally, TGF-β1 was found to enhance CD96 expression on NK cells via SMAD3 signaling. These findings suggest that CD96 is invovled in NK dysfunction against AML blast, and might be a potential target for restoring NK cell function in the fight against AML.

A Single-Cell Analysis of the NK-Cell Landscape Reveals That Dietary Restriction Boosts NK-Cell Antitumor Immunity via Eomesodermin.

Abnormal metabolism in tumor cells represents a potential target for tumor therapy. In this regard, dietary restriction (DR) or its combination with anticancer drugs is of interest as it can impede the growth of tumor cells. In addition to its effects on tumor cells, DR also plays an extrinsic role in restricting tumor growth by regulating immune cells. NK cells are innate immune cells involved in tumor immunosurveillance. However, it remains uncertain whether DR can assist NK cells in controlling tumor growth. In this study, we demonstrate that DR effectively inhibits metastasis of melanoma cells to the lung. Consistent with this, the regression of tumors induced by DR was minimal in mice lacking NK cells. Single-cell RNA sequencing analysis revealed that DR enriched a rejuvenated subset of CD27+CD11b+ NK cells. Mechanistically, DR activated a regulatory network involving the transcription factor Eomesodermin (Eomes), which is essential for NK-cell development. First, DR promoted the expression of Eomes by optimizing mTORC1 signaling. The upregulation of Eomes revived the subset of functional CD27+CD11b+ NK cells by counteracting the expression of T-bet and downstream Zeb2. Moreover, DR enhanced the function and chemotaxis of NK cells by increasing the accessibility of Eomes to chromatin, leading to elevated expression of adhesion molecules and chemokines. Consequently, we conclude that DR therapy enhances tumor immunity through nontumor autonomous mechanisms, including promoting NK-cell tumor immunosurveillance and activation.

A New Look at Immunogenetics of Pregnancy: Maternal Major Histocompatibility Complex Class I Educates Uterine Natural Killer Cells.

Our incomplete knowledge of maternal-fetal interface (MFI) physiology impedes a better understanding of the pathological mechanisms leading to pregnancy complications, such as pre-eclampsia and fetal growth restriction. At the MFI, uterine natural killer (uNK) cells do not attack fetal cells but engage in crosstalk with both fetal and maternal cells to support feto-placental development. However, mother and fetus are genetically half-mismatched and certain combinations of variable immune genes-human leukocyte antigens (HLAs) and killer-cell immunoglobulin-like receptor (KIR), indeed, the most variable gene sets in the genome-associate with pregnancy outcomes, suggesting that these interactions regulate uNK cell function. How do these interactions influence the physiology and pathology at the MFI? Uterine NK cell function is regulated by both maternal and fetal Major Histocompatibility Complex (MHC); however, evidence for fetal cells educating uNK cells is lacking, and new evidence shows that maternal rather than fetal MHC class I molecules educate uNK cells. Furthermore, uNK cell education works through self-recognition by the ancient and conserved NKG2A receptor. Pregnant mice lacking this receptor produce normal litter sizes, but a significant portion of the offspring have low birthweight and abnormal brain development. Evidence from a genome-wide association study of over 150,000 human pregnancies validates the finding because women whose NKG2A receptor is genetically determined to engage their own MHC class I molecules are exposed to lower risk of developing pre-eclampsia, suggesting that maternal uNK cell education is a pre-requisite for a healthy pregnancy and, likely, for healthy offspring too.

Kir6.1, a component of an ATP-sensitive potassium channel, regulates natural killer cell development.

Involved in immunity and reproduction, natural killer (NK) cells offer opportunities to develop new immunotherapies to treat infections and cancer or to alleviate pregnancy complications. Most current strategies use cytokines or antibodies to enhance NK-cell function, but none use ion channel modulators, which are widely used in clinical practice to treat hypertension, diabetes, epilepsy, and other conditions. Little is known about ion channels in NK cells. We show that Kcnj8, which codes for the Kir6.1 subunit of a certain type of ATP-sensitive potassium (K ATP ) channel, is highly expressed in murine splenic and uterine NK cells compared to other K + channels previously identified in NK cells. Kcnj8 expression is highest in the most mature subset of splenic NK cells (CD27 - CD11b + ) and in NKG2A + or Ly49C/I + educated uterine NK cells. Using patch clamping, we show that a subset of NK cells expresses a current sensitive to the Kir6.1 blocker PNU-37883A. Kcnj8 does not participate in NK cell degranulation in response to tumor cells in vitro or rejection of tumor cells in vivo . Transcriptomics show that genes previously implicated in NK cell development are amongst those differentially expressed in CD27 - CD11b + NK cells deficient of Kcnj8 . Indeed, we found that mice with NK-cell specific Kcnj8 gene ablation have fewer CD11b + CD27 - and KLRG-1 + NK cells in the bone barrow and spleen. These results show that the K ATP subunit Kir6.1 has a key role in NK-cell development.

Interleukin-33 and liver natural killer cells: A novel perspective on antitumor activity in liver fibrosis.

Liver fibrosis, heralding the potential progression to cirrhosis and hepatocellular carcinoma (HCC), compromises patient survival and augments post-hepatectomy recurrence. This study examined the detrimental effects of liver fibrosis on the antitumor functions of liver natural killer (NK) cells and the interleukin-33 (IL-33) signaling pathway. Our investigation, anchored in both human physiologies using living and deceased donor livers and the carbon tetrachloride (CCl4)-induced mouse fibrosis model, aimed to show a troubling interface between liver fibrosis and weakened hepatic immunity. The Fibrosis-4 (FIB-4) index emerged as a salient, non-invasive prognostic marker, and its elevation correlated with reduced survival and heightened recurrence after HCC surgery even after propensity matching (n=385). We established a strong correlation between liver fibrosis and liver NK cell dysfunction by developing a method for extracting liver NK cells from the liver graft perfusate. Furthermore, liver fibrosis ostensibly disrupted chemokines and promoted IL-33 expression, impeding liver NK cell antitumor activities, as evidenced in mouse models. Intriguingly, our results implicated IL-33 in diminishing the antitumor responses of NK cells. This interrelation, consistent across both mouse and human studies, coincides with clinical data suggesting that liver fibrosis predisposes patients to an increased risk of HCC recurrence. Our study revealed a critical relationship between liver fibrosis and compromised tumor immunity, emphasizing the potential interference of IL-33 with NK cell function. These insights advocate for advanced immunostimulatory therapies targeting cytokines, such as IL-33, aiming to bolster the hepatic immune response against HCC in the context of liver fibrosis.

Knockdowns of CD3zeta Chain in Primary NK Cells Illustrate Modulation of Antibody-Dependent Cellular Cytotoxicity Against Human Immunodeficiency Virus-1.

Multifaceted natural killer (NK) cell activities are indispensable for controlling human immunodeficiency virus (HIV)-1 transmission and pathogenesis. Among the diverse functions of NK cells, antibody-dependent cellular cytotoxicity (ADCC) has been shown to predict better HIV-1 protection. ADCC is initiated by the engagement of an Fc γ receptor CD16 with an Fc portion of the antibody, leading to phosphorylation of the CD3 ζ chain (CD3ζ) and Fc receptor γ chain (FcRγ) as well as downstream signaling activation. Though CD3ζ and FcRγ were thought to have overlapping roles in NK cell ADCC, several groups have reported that CD3ζ-mediated signals trigger a more robust ADCC. However, few studies have illustrated the direct contribution of CD3ζ in HIV-1-specific ADCC. To further understand the roles played by CD3ζ in HIV-1-specific ADCC, we developed a CD3ζ knockdown system in primary human NK cells. We observed that HIV-1-specific ADCC was inhibited by CD3ζ perturbation. In summary, we demonstrated that CD3ζ is important for eliciting HIV-1-specific ADCC, and this dynamic can be utilized for NK cell immunotherapeutics against HIV-1 infection and other diseases.

14 Natural killer cells have impaired cytotoxicity in advanced renal cell carcinoma

Abstract Background Natural killer (NK) cells are key mediators of anti-tumor activity in multiple cancers, including clear cell renal cell carcinoma (ccRCC). However, the phenotype and function of NK cells across different disease stages of ccRCC is incompletely characterized. Methods Single-cell RNA (scRNA)-sequencing (10x Genomics) data from tumor and adjacent normal kidney from ccRCC was analyzed at multiple clinical stages (localized – stage I/II/III; and advanced – stage IV). Graph-based clustering and lineage markers were used to identify distinct NK cell populations. Differential gene expression analysis was performed to further investigate NK cell phenotype and to derive a gene expression signature (GES). Gene signatures from NK cell subclusters of interest were used to interrogate bulk transcriptomic datasets and expression with clinical outcomes. Tumor-infiltrating NK cell function (cytokine production and cytotoxicity) was assessed by isolation of live NK cells from ccRCC tissue, co-culture with K562 target cells, and measurement of cytokine (IFNgamma) and cytotoxicity (CD107a) markers by flow cytometry. Results Single-cell transcriptomic data were analyzed from 13 patients with ccRCC (tumor and normal kidney), resulting in 21,139 high-quality NK cells. Patients with advanced/metastatic RCC had a lower proportion of NK cells versus total immune cells in the tumor microenvironment compared to normal kidney (p=0.036) and localized ccRCC (p=0.088). Clustering analysis revealed 6 distinct NK cell subsets. The C0.Bright-like NK cell cluster was significantly enriched in advanced ccRCC compared to localized ccRCC (p=0.048) and normal kidney (p=0.0059), expressed markers of tissue residency (ZNF683, ITGA1, CD9, ITGAE), and had decreased expression of cytotoxicity genes (GZMB, PRF1). A GES signature composed of genes upregulated in the dysfunctional C0.Bright-like NK cell cluster was used to interrogate bulk RNA-sequencing data from The Cancer Genome Atlas clear cell cohort, providing validation in a large, independent cohort, of an increase in this dysfunctional NK subset in advanced ccRCC compared to localized ccRCC (p=0.00039) and normal tissue (p=5.3e-05). To functionally confirm the decreased cytotoxicity of this dysfunctional NK population, CD45+CD56+CD3- NK cells were isolated from advanced ccRCC, and co-cultured with K562 target cells. Consistent with the transcriptomic phenotype, tumor-resident CD49a+CD9+ NK cells had cytokine production (IFNgamma) but decreased markers of cytotoxicity (CD107a) compared to CD49a-CD9- NK cells. By contrast, CD49a+CD9+ NK cells isolated from peripheral blood or normal kidney tissue maintained cytotoxic activity. Conclusions Among patients with ccRCC, a single-cell transcriptomic analysis revealed heterogeneous NK cell populations. A dysfunctional tumor resident NK cell phenotype was enriched among patients with advanced disease in ccRCC, and functionally confirmed to have diminished cytotoxicity. This study therefore provides insight into a new axis of immune dysfunction – decreased NK-mediated cytotoxicity – in advanced ccRCC. An improved understanding of NK cell dysfunction within ccRCC may provide a foundation for therapeutic restoration of NK-mediated anti-tumor activity in ccRCC. DOD CDMRP Funding: yes

Neutrophil-like Monocytes Increase in Patients with Colon Cancer and Induce Dysfunctional TIGIT+ NK Cells.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous family of immune cells including granulocytic (CD14neg/CD15+/HLA-DRneg) and monocytic subtypes (CD14+/CD15neg/HLA-DRneg). In the present study, we found a population of monocytes expressing the granulocyte marker CD15 that significantly increased in both peripheral blood (PB) and tumoral tissues of patients with colorectal cancer (CRC). Further phenotypical analysis confirmed the granulocytic-like features of this monocyte subpopulation that is associated with an increase in granulocyte-monocyte precursors (GMPs) in the PB of these patients (pts). Mechanistically, this granulocyte-like monocyte population suppressed NK cell activity by inducing TIGIT and engaging NKp30. Accordingly, an increased frequency of TIGIT+ NK cells with impaired functions was found in both the PB and tumoral tissue of CRC pts. Collectively, we provided new mechanistic explanations for tumor immune escape occurring in CRC by showing the increase in this new kind of MDSC, in both PB and CRC tissue, which is able to significantly impair the effector functions of NK cells, thereby representing a potential therapeutic target for cancer immunotherapy.

Development in the Study of Natural Killer Cells for Malignant Peritoneal Mesothelioma Treatment.

Malignant peritoneal mesothelioma (MPeM) is a rare primary malignant tumor originating from peritoneal mesothelial cells. Insufficient specificity of the symptoms and their frequent reappearance following surgery make it challenging to diagnose, creating a need for more efficient treatment options. Natural killer cells (NK cells) are part of the innate immune system and are classified as lymphoid cells. Under the regulation of activating and inhibiting receptors, NK cells secrete various cytokines to exert cytotoxic effects and participate in antiforeign body, antiviral, and antitumor activities. This review provides a comprehensive summary of the specific alterations observed in NK cells following MPeM treatment, including changes in cell number, subpopulation distribution, active receptors, and cytotoxicity. In addition, we summarize the impact of various therapeutic interventions, such as chemotherapy, immunotherapy, and targeted therapy, on NK cell function post-MPeM treatment.

Striking a balance: the Goldilocks effect of CD8α expression on NK cells.

NK cells are cytotoxic innate immune cells involved in antitumor immunity, and they provide a treatment option for patients with acute myeloid leukemia (AML). In this issue of the JCI, Cubitt et al. investigated the role of CD8α, a coreceptor present on approximately 40% of human NK cells. IL-15 stimulation of CD8α- NK cells induced CD8α expression via the RUNX3 transcription factor, driving formation of a unique induced CD8α (iCD8α+) population. iCD8α+ NK cells displayed higher proliferation, metabolic activity, and antitumor cytotoxic function compared with preexisting CD8α+ and CD8α- subsets. Therefore, CD8α expression can be used to define a potential dynamic spectrum of NK cell expansion and function. Because these cells exhibit enhanced tumor control, they may be used to improve in NK cell therapies for patients with AML.