Natural Killer Cells In Tissues Research Articles

Identification of a Novel Activated NK-Associated Gene Score Associated with Diagnosis and Biological Therapy Response in Ulcerative Colitis

Introduction: Natural killer (NK) cells are associated with the pathogenesis of ulcerative colitis (UC); however, their precise contributions remain unclear. The present study aimed to investigate the diagnostic value of the activated NK-associated gene (ANAG) score in UC and evaluate its predictive value in response to biological therapy. Methods: Bulk RNA-seq and scRNA-seq datasets were obtained from the Gene Expression Omnibus (GEO) and Single Cell Portal (SCP) databases. In the bulk RNA-seq, differentially expressed genes (DEGs) were screened by the “Batch correction” and “Robust rank aggregation” (RRA) methods. The immune infiltration landscape was estimated using single-sample gene set enrichment analysis (ssGSEA) and CIBERSORT. DEGs that correlated with activated NK cells were identified as activated NK-associated genes (ANAGs). Protein-protein interaction (PPI) analysis and least absolute shrinkage and selection operator (LASSO) regression were used to screen key ANAGs and establish an ANAG score. The expression levels of the four key ANAGs were validated in human samples by real-time quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence. The potential therapeutic drugs for UC were identified using the DSigDB database. Through scRNA-seq data analysis, the cell scores based on the ANAGs were calculated by “AddModuleScore” and “AUCell.” Results: Immune infiltration analysis revealed a higher abundance of activated NK cells in noninflamed UC tissues (ssGSEA, p < 0.001; CIBERSORT, p < 0.01). Fifty-four DEGs correlated with activated NK cells were identified as ANAGs. The ANAG score was established using four key ANAGs (SELP, TIMP1, MMP7, and ABCG2). The ANAG scores were significantly higher in inflamed tissues (p < 0.001) and in biological therapy nonresponders (NR) tissues before treatment (golimumab, p < 0.05; ustekinumab, p < 0.001). The ANAG score demonstrated an excellent diagnostic value (AUC = 0.979). Patients with higher ANAG scores before treatment were more likely to experience a lack of response to golimumab or ustekinumab (golimumab, p < 0.05; ustekinumab, p < 0.001). Conclusion: This study established a novel ANAG score with the ability to precisely diagnose UC and distinguish the efficacy of biological treatment.

Single-cell transcriptome sequencing to explore the infiltration and disappearance of NK cells in liver cancer.

e14520 Background: The emergence of tumor immunotherapy such as immune checkpoint blocking has greatly promoted the development of Hepatocellular carcinoma (HCC) treatment. However, the response rate of HCC patients to immunotherapy is not high, and the probability of adverse reactions is high. Natural killer (NK) cells play a crucial role in inhibiting the proliferation and metastasis of tumor cells and are expected to become a new hope for tumor therapy. Methods: The HCC single-cell transcriptome atlas was constructed by using the tumor tissues, adjacent tissues, peripheral blood of HCC patients. To emulate the hypoxic state within the tumor, NK cells were treated with rotenone, and the post-rotenone treatment changes of NK cells in transcriptome levels were evaluated using qPCR. The proliferation, apoptosis, and cytotoxicity of NK cells were assessed via flow cytometry. The study also investigated the role of c-Jun N-terminal protein kinase (JNK) in NK cell function by applying the JNK inhibitor tanzisertib (CC-930) in vitro. The impact of JNK inhibition on the tumor-killing potential of NK cells was examined in vivo using tumor-bearing mice NCG (NOD/ShiLtJ-Prkdcem26Cd52Il2rgem26Cd22/Gpt). Results: Analysis of the source of NK cell subsets found that the specific NK cells in tumor tissues were tissue-resident NK cells (trNK). Both RNA velocity analysis and pseudo-time sequence analysis suggested that trNK cells differentiated from PBMC-1 NK cells. Upon treatment of PBMC-1 NK cells with Tanzisertib, we observed inhibition of NK cell apoptosis. Through the subcutaneous tumor formation experiment of NCG mice, Tanzisertib-treated NK cells were transferred into tumor-bearing mice. Notably, we observed a significant reduction in tumor weight (Before treatment: 0.19g, 0.19g, 0.22g, 0.24g, 0.26g, 0.27g; After treatment: 0.16g, 0.17g, 0.17g, 0.19g, 0.21g, 0.23g; P value = 0.049). TUNEL assay confirmed a significant increase number of apoptotic cells within the tumor and an increased number of infiltrated NK cells. Conclusions: The NK cells in HCC tumors are likely derived from the infiltration of NK cells in peripheral blood. Importantly, the inhibition of JNK function can significantly inhibit the apoptosis of NK cells and enhance the killing ability of NK cells against tumor cells in vivo.

Killing capacity analysis of tumor-infiltrating cytotoxic lymphocytes and impact on lymph node metastasis in differentiated papillary carcinoma of thyroid with the BRAF V600E mutation

BackgroundCytotoxic lymphocytes (CLs) express potent toxins, including perforin (P) and granzyme-B (G), which brings about target cell death. The purpose of this study was to evaluate the killing capacity of tumor-infiltrating CLs by means of P and G analysis, and explore the association with lymph node metastasis in papillary carcinoma of thyroid (PTC) without Hashimoto’s thyroiditis (HT).MethodsInfiltration of lymphocytes in PTC was observed in frozen sections. Both fresh tumor tissues and paracancerous tissues with lymphocyte infiltration were collected and prepared into a single cell suspension. Flow cytometry was used to detect the percentages of CD3+P+, CD3+G+, CD8+P+, and CD8+G+ T lymphocytes (TLs) and CD16-CD56+P+ and CD16-CD56+G+ natural killer (NK) cells. Finally, we investigated differential expression of P and G in NK cells and cytotoxic T lymphocytes (CTLs) in paired tumor tissues (group T, n = 44) and paracancerous tissues (group N, n = 44) from patients with PTC with the BRAF V600E mutation. Furthermore, patients were divided into two groups according to whether cervical central lymph node metastasis (CCLNM) existed: group A (with lymph node metastases, n = 27) and group B (with nonlymph node metastases, n = 17). Patients were also divided into three groups according to the total number of positive CCLNM: group B, group C (with low-level lymph node metastases, less than 5, n = 17) and group D (with high-level lymph node metastases, no less than 5, n = 10).ResultsThe percentage of CD3+P+ CTLs was significantly higher in group N than in group T (P < 0.05). The percentage of CD8+G+ CTLs was significantly higher in group T than in group N (P < 0.05). The percentages of CD3+G+, CD16-CD56+P+and CD16-CD56+G+ NK cells showed no significant difference in either group T or group N (P > 0.05). The percentages of CD3+P+ CTLs in group A and group C were significantly higher in the paracancerous tissue than in the tumor tissue (P < 0.05). The percentages of CD8+G+ CTLs in group A and group C were significantly higher in the tumor tissues than in the paracancerous tissues (P < 0.05). The percentage of CD16-CD56+G+ NK cells in group D was significantly higher in the tumor tissues than in the paracancerous tissues (P < 0.05).ConclusionsThe killing capacity of infiltrating CLs in PTC differed between tumor tissues and paracancerous tissues. In cases with CCLNM, higher expression of CD16-CD56+G+ NK cells in tumor tissues may be associated with a high risk of lymph node metastasis.

Circulating NK cells establish tissue residency upon acute infection of skin and mediate accelerated effector responses to secondary infection

Natural killer (NK) cells are present in the circulation and can also be found residing in tissues, and these populations exhibit distinct developmental requirements and are thought to differ in terms of ontogeny. Here, we investigate whether circulating conventional NK (cNK) cells can develop into long-lived tissue-resident NK (trNK) cells following acute infections. We found that viral and bacterial infections of the skin triggered the recruitment of cNK cells and their differentiation into Tcf1hiCD69hi trNK cells that share transcriptional similarity with CD56brightTCF1hi NK cells in human tissues. Skin trNK cells arose from interferon (IFN)-γ-producing effector cells and required restricted expression of the transcriptional regulator Blimp1 to optimize Tcf1-dependent trNK cell formation. Upon secondary infection, trNK cells rapidly gained effector function and mediated an accelerated NK cell response. Thus, cNK cells redistribute and permanently position at sites of previous infection via a mechanism promoting tissue residency that is distinct from Hobit-dependent developmental paths of NK cells and ILC1 seeding tissues during ontogeny.

Autophagy-mediated NKG2D internalization impairs NK cell function and exacerbates radiation pneumonitis.

Radiation pneumonitis is a critical complication that constrains the use of radiation therapy for thoracic malignancies, leading to substantial morbidity via respiratory distress and lung function impairment. The role of Natural killer (NK) cells in inflammatory diseases is well-documented; however, their involvement in radiation pneumonitis is not fully understood. To explore the involvement of NK cells in radiation pneumonitis, we analyzed tissue samples for NK cell presence and function. The study utilized immunofluorescence staining, western blotting, and immunoprecipitation to investigate CXCL10 and ROS levels, autophagy activity, and NKG2D receptor dynamics in NK cells derived from patients and animal models subjected to radiation. In this study, we observed an augmented infiltration of NK cells in tissues affected by radiation pneumonitis, although their function was markedly diminished. In animal models, enhancing NK cell activity appeared to decelerate the disease progression. Concomitant with the disease course, there was a notable upsurge in CXCL10 and ROS levels. CXCL10 was found to facilitate NK cell migration through CXCR3 receptor activation. Furthermore, evidence of excessive autophagy in patient NK cells was linked to ROS accumulation, as indicated by immunofluorescence and Western blot analyses. The association between the NKG2D receptor and its adaptor proteins (AP2 subunits AP2A1 and AP2M1), LC3, and lysosomes was intensified after radiation exposure, as demonstrated by immunoprecipitation. This interaction led to NKG2D receptor endocytosis and subsequent lysosomal degradation. Our findings delineate a mechanism by which radiation-induced lung injury may suppress NK cell function through an autophagy-dependent pathway. The dysregulation observed suggests potential therapeutic targets; hence, modulating autophagy and enhancing NK cell activity could represent novel strategies for mitigating radiation pneumonitis.

Barcode clonal tracking of tissue-resident immune cells in rhesus macaque highlights distinct clonal distribution pattern of tissue NK cells.

Tissue resident (TR) immune cells play important roles in facilitating tissue homeostasis, coordinating immune responses against infections and tumors, and maintaining immunological memory. While studies have shown these cells are distinct phenotypically and functionally from cells found in the peripheral blood (PB), the clonal relationship between these populations across tissues has not been comprehensively studied in primates or humans. We utilized autologous transplantation of rhesus macaque hematopoietic stem and progenitor cells containing high diversity barcodes to track the clonal distribution of T, B, myeloid and natural killer (NK) cell populations across tissues, including liver, spleen, lung, and gastrointestinal (GI) tract, in comparison with PB longitudinally post-transplantation, in particular we focused on NK cells which do not contain endogenous clonal markers and have not been previously studied in this context. T cells demonstrated tissue-specific clonal expansions as expected, both overlapping and distinct from blood T cells. In contrast, B and myeloid cells showed a much more homogeneous clonal pattern across various tissues and the blood. The clonal distribution of TR NK was more heterogenous between individual animals. In some animals, as we have previously reported, we observed large PB clonal expansions in mature CD56-CD16+ NK cells. Notably, we found a separate set of highly expanded PB clones in CD16-CD56- (DN) NK subset that were also contributing to TR NK cells in all tissues examined, both in TR CD56-CD16+ and DN populations but absent in CD56+16- TR NK across all tissues analyzed. Additionally, we observed sets of TR NK clones specific to individual tissues such as lung or GI tract and sets of TR NK clones shared across liver and spleen, distinct from other tissues. Combined with prior functional data that suggests NK memory is restricted to liver or other TR NK cells, these clonally expanded TR NK cells may be of interest for future investigation into NK cell tissue immunological memory, with implications for development of NK based immunotherapies and an understanding of NK memory.

Heterogeneity of liver NK cells

<p indent="0mm">Natural killer (NK) cells have attracted much attention since their discovery in the 1970s; however, earlier studies mainly focused on circulating NK cells. In the past decade, the heterogeneity of NK cells in different tissues has begun to attract increasing attention. As an organ containing abundant and heterogeneous NK cell populations, the liver provides a good window for studying them. It is now commonly accepted that bulk liver NK cells comprise circulating conventional NK cells and liver-resident NK cells. This review summarized and discussed the developmental origin, differentiation, transcriptional regulation, and immune functions of liver-resident NK cells and conventional NK cells, providing new perspectives for studying liver regional immunity.

Single-Cell Sequencing of Immune Cells in Human Aortic Dissection Tissue Provides Insights Into Immune Cell Heterogeneity.

BackgroundInflammation plays an important role in the progression of sporadic aortic dissection (AD). Immune cells, especially macrophages, infiltrate the aorta and secrete inflammatory cytokines and matrix metalloproteinases to cause degradation of the extracellular matrix, thereby contributing to the pathogenesis of AD. However, the cellular heterogeneity within these immune cells has not been fully characterized.MethodsWe used single-cell RNA sequencing to profile the transcriptomes of all immune cells in AD tissue and normal aorta. Using magnetic-activated cell sorting gating on CD45, we obtained a higher resolution identification of the immune cell subsets in the aorta.ResultsWe observed significant differences in the proportion of major immune cell subpopulations between AD and normal aorta tissues. Macrophages accounted for a higher percentage in the normal aorta, while the proportions of T cells, B cells and natural killer (NK) cells were all increased in AD tissues. Macrophage clusters that expanded in AD tissues originated primarily from circulating monocytes and expressed genes encoding proinflammatory cytokines and molecules involved in tissue repair. T and NK cells in AD tissues exhibited enhanced cytotoxic properties. A cluster of CD4+ T cells that had expanded in AD tissues was Th17-like and might contribute to the pathogenesis of AD. Cell–cell interaction analysis highlighted the increased communication between macrophages and T cells, which primarily regulated the costimulation of T cells.ConclusionsOur study provides a comprehensive characterization of immune cells in the dissected aorta with an emphasis on the role of macrophages and T cells. The information from our study improves our understanding of immune mechanisms in AD formation and helps to identify additional useful targets for early diagnosis or therapy of AD.

Methods for Isolating and Defining Single-Cell Transcriptomes of Tissue-Resident Human NK Cells.

Natural killer (NK) cells are innate lymphocytes that control tumors and microbial infections. Human NK cells are transcriptomically and phenotypically heterogeneous. The site where NK cells develop and reside determines their phenotype and effector functions. Our current knowledge about human NK cells is primarily from blood- and bone marrow-derived NK cells. The major limitation in formulating organ-specific clinical therapy is the knowledge gap on how tissue-resident NK cells develop, home, and function. Thus, it is crucial to define the transcriptomic profiles and the transcriptional regulation of tissue-resident NK cells. The major challenges in studying tissue-resident NK cells include their total number and the complexity of the tissue. Additionally, during isolation, keeping them viable and naïve without activation are challenging tasks. Here, we provide methods for isolating and performing transcriptomic analyses of NK cells at the individual cell level. Single-cell RNA sequencing provides a higher resolution of cellular heterogeneity and a better understanding of cell-cell interactions within the microenvironment. Using these methods, we can efficiently identify distinct populations of NK cells in tissues and define their unique transcriptomic profiles.

Activating chimeric receptor on IL-15 armored NK cells to improve in vitro and in vivo tumor response within the liver following regional delivery.

e14517 Background: Colorectal cancer liver metastases (CRCLM) are a major source of morbidity and mortality. Historically, curative therapy has been limited to surgical resection, but only a small fraction of patients are eligible. Cellular immunotherapy has shown promise in hematologic cancers, but challenges to solid tumor therapy remain, including lymphocyte trafficking, elevated interstitial fluid pressures, and immunosuppression. Regional intravascular infusion is a non-surgical, minimally invasive procedure commonly used in liver cancer to deliver therapeutics, which can be augmented by Pressure Enabled Drug Delivery (PEDD). We hypothesized that utilizing established regional delivery strategies to administer natural killer (NK) cells engineered to express a natural killer group 2, member D (NKG2D) activating chimeric receptor and membrane bound IL-15 (CAR NKG2D cells) could increase anti-tumor activity against liver cancer. Methods: In vitro cytotoxicity of CAR NKG2D NK cells was determined in co-culture systems. CRCLM-bearing NSG mice were treated with either CAR NKG2D, non-transduced NK cells (NT-NK), or vehicle via portal vein (PV) for regional PEDD or tail vein (TV) for systemic delivery (SD). Tumor burden was measured via tumor bioluminescence. Mann-Whitney tests were performed for statistical comparisons. Correlation of NKG2D ligand expression in tissue and serum was measured by CODEX and Luminex. Results: Multiple NKG2D ligands are highly expressed in hepatocellular and colorectal carcinoma cell lines (HCC and CRC respectively). As such, these cells lines are highly susceptible to NKG2D-mediated cytotoxicity. CAR NKG2D NK cells were 3- to 4-fold more potent in vitro than NT-NK cells against multiple HCC and CRC cell lines, including those bearing Ras pathway mutations. Using a mouse model of locoregional delivery under high pressure (10 mL/minute), we show that significant tumor reduction (p &lt; 0.05) is only achieved when CAR NKG2D NK cells, but not vehicle or NT-NK cells, were delivered via PV and not via TV. Recovery of CAR NKG2D NK cells in hepatic tissues was on average 2-fold higher after administration via PV than that observed after TV delivery (p = 0.0001). PV delivery of NT-NK cells did not result in appreciable liver engraftment or tumor growth inhibition. Conclusions: CAR NKG2D NK cells demonstrate enhanced in vitro and in vivo cytotoxicity against CRC and HCC cell lines. Significant tumor control using regional delivery in initial studies support continued clinical development. NKX101 is an investigational agent comprised of CAR NKG2D NK cells being evaluated in a phase 1 clinical study for treatment of relapsed/refractory acute myeloid leukemia or higher risk myelodysplastic syndrome. Studies are ongoing to understand NKX101 kinetics, role of delivery pressure, and activity in combination in preclinical models of CRCLM.

Lymph Node Delivery Strategy Enables the Activation of Cytotoxic T Lymphocytes and Natural Killer Cells to Augment Cancer Immunotherapy.

Lymph nodes are the main sites for immune activation and surveillance. Effective delivery of immunomodulators into lymph nodes to trigger antitumor immunity is essential for cancer treatment. Here, we propose a lymph node delivery strategy to modulate the immune response by activating cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells simultaneously. Novel pH/redox dual-sensitive micelles were prepared using poly(l-histidine)-poly(ethylene glycol) (PLH-PEG) as a skeleton, which can effectively deliver immunomodulators to the lymph nodes due to their suitable particle size. At 48 h after subcutaneous injection, the accumulation efficiency in lymph nodes increased 8.12-fold compared with the control group. Subsequently, Trp2/CpG-coloaded pH/redox dual-sensitive micelles (Trp2/CpG-NPs) acted on antigen-presenting cells, fully promoting CTL activation through dendritic cell antigen cross-presentation and macrophage repolarization. IL-15-loaded pH/redox dual-sensitive micelles (IL-15-NPs) were developed to activate the killing effect of NK cells by interacting with IL-15 receptors. In the tumor-bearing mice model, this lymph node delivery strategy showed significant antitumor efficiency and the tumor inhibition rate reached 93.76%. Meanwhile, the infiltration of CTLs and NK cells in tumor tissues increased, and the immunosuppressive microenvironment was relieved by the repolarization of macrophages from M2-type to M1-type. Overall, this study highlighted the potential of the lymph node delivery strategy for cancer immunotherapy.

GPR56 inhibits chemotaxis of human Natural Killer and TEMRA lymphocytes

Abstract Within the human immune system, the expression of GPR56, an adhesion G-protein couple receptor, is restricted to cytotoxic Natural Killer (NK) and T lymphocytes, including T effector memory re-expressing CD45RA (TEMRA) cells. In primary NK cells, GPR56 acts as an inhibitory receptor, as it diminishes their ability to eliminate target cells. Overexpression of GPR56 in immortal NK-92 cells also leads to robust inhibition of cell chemotaxis. GPR56 is speculated to promote retention of cytotoxic lymphocytes in inflamed peripheral tissues. Thus, GPR56 has the potential to regulate immune responses that may lead to excessive inflammation and autoimmunity. The aim of the present study was, therefore, to examine whether GPR56 mediates cytotoxic immune cell functions and whether GPR56 expression is altered in autoimmune diseases. To tackle these questions, we first compared expression of GPR56 in healthy and autoimmune disease patient tissues using scRNA-seq datasets. Next, we tested whether stimulation of GPR56 with a monoclonal antibody modulated the migratory capacity of NK and CD8+ TEMRA cells. We found that chemotaxis toward CXCL12, IL-8, and CX3CL1 was strikingly inhibited by GPR56. Using bulk RNA-seq, we found GPR56-stimulation impacted a multitude of signaling cascades that regulate cell chemotaxis. Taken together, our results confirm that GPR56 is a marker for NK and TEMRA cells in healthy and autoimmune patient tissues and establish GPR56 as a key regulator of lymphocyte chemotaxis.

Abstract B87: NK cells lose their ability to control MHC-I-deficient tumor cells outside circulation

Abstract A common tumor immune-evasion mechanism is downregulation of major histocompatibility complex Class-I (MHC-I) that enables malignant cell escape from cytotoxic T-cell responses. This strategy also contributes to nonresponsiveness of tumors to T-cell targeted immune-checkpoint blockade. MHC-I is an antigen-presenting molecule that also functions as an inhibitory ligand for natural killer (NK) cells. Thus, loss of MHC-I should render cells susceptible to NK cell-mediated cytotoxicity. However, this does not always occur. Previously it was demonstrated that NK cells were able to strongly reject MHC-I-deficient bone marrow cells in the circulation, yet they failed to reject MHC-I-deficient organ grafts, suggesting restricted NK cell cytotoxicity in tissues. We hypothesized that a similar NK cell tolerance to MHC-I-deficient cells occurs in the context of solid cancers. We compared NK cell recruitment and activation using WT and MHC-I-deficient B16F10 melanoma models. We demonstrated that NK cells eradicate circulating MHC-I−/− B16F10 cells, effectively preventing tumor metastasis to the lungs. In contrast, NK cells failed to clear MHC-I−/− B16F10 tumors when implanted subcutaneously, nor was the growth of these tumors affected by NK cell depletion. Interestingly, spontaneous lymph node (LN) metastasis from MHC-I-deficient solid tumors was fully abrogated in an NK cell-dependent manner, indicating functional inhibition of NK cells in peripheral tissues, but not in circulation or draining lymphatics. In conclusion, we demonstrate NK cell tolerance to MHC-I-deficient tumor cells in tissues, but not in circulation, which suggests the presence of non-MHC-I NK cell-inhibitory signals in solid organs. Our research uncovers a fundamental aspect of NK cell biology and will open up the possibility of new NK cell-based therapeutic strategies to control solid tumors that escape cytotoxic CD8+ T-cell responses by downregulating MHC-I. Citation Format: Marta Requesens, Mark Bunting, Maulik Vyas, Shawn Demehri. NK cells lose their ability to control MHC-I-deficient tumor cells outside circulation [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr B87.

Natural Killer Cells in the Lungs.

The lungs, a special site that is frequently challenged by tumors, pathogens and other environmental insults, are populated by large numbers of innate immune cells. Among these, natural killer (NK) cells are gaining increasing attention. Recent studies have revealed that NK cells are heterogeneous populations consisting of distinct subpopulations with diverse characteristics, some of which are determined by their local tissue microenvironment. Most current information about NK cells comes from studies of NK cells from the peripheral blood of humans and NK cells from the spleen and bone marrow of mice. However, the functions and phenotypes of lung NK cells differ from those of NK cells in other tissues. Here, we provide an overview of human and mouse lung NK cells in the context of homeostasis, pathogenic infections, asthma, chronic obstructive pulmonary disease (COPD) and lung cancer, mainly focusing on their phenotype, function, frequency, and their potential role in pathogenesis or immune defense. A comprehensive understanding of the biology of NK cells in the lungs will aid the development of NK cell-based immunotherapies for the treatment of lung diseases.

Retained NK Cell Phenotype and Functionality in Non-alcoholic Fatty Liver Disease.

Non-alcoholic fatty liver disease (NAFLD), and the progressive stage non-alcoholic steatohepatitis (NASH), is the predominant cause of chronic liver disease globally. As part of the complex pathogenesis, natural killer (NK) cells have been implicated in the development of liver inflammation in experimental murine models of NASH. However, there is a lack of knowledge on how NK cells are affected in humans with this disease. Here, we explored the presence of disease-specific changes within circulating and tissue-resident NK cell populations, as well as within other major immune cell subsets, in patients with liver biopsy-confirmed NAFLD. Using 18-color-flow cytometry, substantial changes were observed in certain myeloid populations in patients as compared to controls. NK cell numbers, on the other hand, were not altered. Furthermore, only minor differences in expression of activating and inhibitory NK cell receptors were noted, with the exception of an increased expression of NKG2D on NK cells from patients with NASH. NK cell differentiation remained constant, and NK cells from these patients retain their ability to respond adequately upon stimulation. Instead, considerable alterations were observed between liver, adipose tissue, and peripheral blood NK cells, independently of disease status. Taken together, these results increase our understanding of the importance of the local microenvironment in shaping the NK cell compartment and stress the need for further studies exploring how NASH affects intrahepatic NK cells in humans.

The Natural Cytotoxicity Receptors in Health and Disease.

The Natural Cytotoxicity Receptors (NCRs), NKp46, NKp44, and NKp30, were some of the first human activating Natural Killer (NK) cell receptors involved in the non-MHC-restricted recognition of tumor cells to be cloned over 20 years ago. Since this time many host- and pathogen-encoded ligands have been proposed to bind the NCRs and regulate the cytotoxic and cytokine-secreting functions of tissue NK cells. This diverse set of NCR ligands can manifest on the surface of tumor or virus-infected cells or can be secreted extracellularly, suggesting a remarkable NCR polyfunctionality that regulates the activity of NK cells in different tissue compartments during steady state or inflammation. Moreover, the NCRs can also be expressed by other innate and adaptive immune cell subsets under certain tissue conditions potentially conferring NK recognition programs to these cells. Here we review NCR biology in health and disease with particular reference to how this important class of receptors regulates the functions of tissue NK cells as well as confer NK cell recognition patterns to other innate and adaptive lymphocyte subsets. Finally, we highlight how NCR biology is being harnessed for novel therapeutic interventions particularly for enhanced tumor surveillance.

Uterine Natural Killer Cells.

Natural killer (NK) cells are members of a rapidly expanding family of innate lymphoid cells (ILCs). While most previously studied NK cells were derived from the mouse spleen and circulate in the blood, recently others and we found tissue-resident NK (trNK) cells in many tissues that resemble group 1 ILCs (ILC1s). During pregnancy, NK cells are the most abundant lymphocytes in the uterus at the maternal-fetal interface and are involved in placental vascular remodeling. Prior studies suggested that these uterine NK (uNK) cells are mostly derived from circulating NK cells. However, the murine virgin uterus contains mostly trNK cells and it has been challenging to determine their contribution to uNK cells in pregnancy as well as other potential function(s) of uNK cells due to the dynamic microenvironment in the pregnant uterus. This review focuses on the origins and functions of the heterogeneous populations of uNK cells during the course of murine pregnancy.

Assessment of natural killer cells in tissues from patients with cervical abnormalities

Assessment of natural killer cells in tissues from patients with cervical abnormalities

Human Bone Marrow-Resident Natural Killer Cells Have a Unique Transcriptional Profile and Resemble Resident Memory CD8+ T Cells.

Human lymphoid tissues harbor, in addition to CD56bright and CD56dim natural killer (NK) cells, a third NK cell population: CD69+CXCR6+ lymphoid tissue (lt)NK cells. The function and development of ltNK cells remain poorly understood. In this study, we performed RNA sequencing on the three NK cell populations derived from bone marrow (BM) and blood. In ltNK cells, 1,353 genes were differentially expressed compared to circulating NK cells. Several molecules involved in migration were downregulated in ltNK cells: S1PR1, SELPLG and CD62L. By flow cytometry we confirmed that the expression profile of adhesion molecules (CD49e−, CD29low, CD81high, CD62L−, CD11c−) and transcription factors (Eomeshigh, Tbetlow) of ltNK cells differed from their circulating counterparts. LtNK cells were characterized by enhanced expression of inhibitory receptors TIGIT and CD96 and low expression of DNAM1 and cytolytic molecules (GZMB, GZMH, GNLY). Their proliferative capacity was reduced compared to the circulating NK cells. By performing gene set enrichment analysis, we identified DUSP6 and EGR2 as potential regulators of the ltNK cell transcriptome. Remarkably, comparison of the ltNK cell transcriptome to the published human spleen-resident memory CD8+ T (Trm) cell transcriptome revealed an overlapping gene signature. Moreover, the phenotypic profile of ltNK cells resembled that of CD8+ Trm cells in BM. Together, we provide transcriptional and phenotypic data that clearly distinguish ltNK cells from both the CD56bright and CD56dim NK cells and substantiate the view that ltNK cells are tissue-resident cells, which are functionally restrained in killing and have low proliferative activity.

Uterine Natural Killer Cells: Functional Distinctions and Influence on Pregnancy in Humans and Mice.

Our understanding of development and function of natural killer (NK) cells has progressed significantly in recent years. However, exactly how uterine NK (uNK) cells develop and function is still unclear. To help investigators that are beginning to study tissue NK cells, we summarize in this review our current knowledge of the development and function of uNK cells, and what is yet to be elucidated. We compare and contrast the biology of human and mouse uNK cells in the broader context of the biology of innate lymphoid cells and with reference to peripheral NK cells. We also review how uNK cells may regulate trophoblast invasion and uterine spiral arterial remodeling in human and murine pregnancy.