Gene and protein characteristics reflect functional diversity of CD56dim and CD56bright NK cells

Characterizing the Tumor Microenvironment and Its Prognostic Impact in Breast Cancer

The tumor microenvironment (TME) is crucial in cancer development and therapeutic response. Immunotherapy is increasingly recognized as a critical component of cancer treatment. While immunotherapies have shown efficacy in various cancers, including breast cancer, patient responses vary widely. Some patients receive significant benefits, while others experience minimal or no improvement. This disparity underscores the complexity and diversity of the immune system. In this study, we investigated the immune landscape and cell-cell communication within the TME of breast cancer through integrated analysis of bulk and single-cell RNA sequencing data. We established profiles of tumor immune infiltration that span across a broad spectrum of adaptive and innate immune cells. Our clustering analysis of immune infiltration identified three distinct patient groups: high T cell abundance, moderate infiltration, and low infiltration. Patients with low immune infiltration exhibited the poorest survival rates, while those in the moderate infiltration group showed better outcomes than those with high T cell abundance. Moreover, the high cell abundance group was associated with a greater tumor burden and higher rates of TP53 mutations, whereas the moderate infiltration group was characterized by a lower tumor burden and elevated PIK3CA mutations. Analysis of an independent single-cell RNA-seq breast cancer dataset confirmed the presence of similar infiltration patterns. Further investigation into ligand-receptor interactions within the TME unveiled significant variations in cell-cell communication patterns among these groups. Notably, we found that the signaling pathways SPP1 and EGF were exclusively active in the low immune infiltration group, suggesting their involvement in immune suppression. This work comprehensively characterizes the composition and dynamic interplay in the breast cancer TME. Our findings reveal associations between the extent of immune infiltration and clinical outcomes, providing valuable prognostic information for patient stratification. The unique mutations and signaling pathways associated with different patient groups offer insights into the mechanisms underlying diverse tumor immune infiltration and the formation of an immunosuppressive tumor microenvironment.

Aging and Inflammation

Aging can be conceptualized as the progressive disequilibrium between stochastic damage accumulation and resilience mechanisms that continuously repair that damage, which eventually cause the development of chronic disease, frailty, and death. The immune system is at the forefront of these resilience mechanisms. Indeed, aging is associated with persistent activation of the immune system, witnessed by a high circulating level of inflammatory markers and activation of immune cells in the circulation and in tissue, a condition called "inflammaging." Like aging, inflammaging is associated with increased risk of many age-related pathologies and disabilities, as well as frailty and death. Herein we discuss recent advances in the understanding of the mechanisms leading to inflammaging and the intrinsic dysregulation of the immune function that occurs with aging. We focus on the underlying mechanisms of chronic inflammation, in particular the role of NF-κB and recent studies targeting proinflammatory mediators. We further explore the dysregulation of the immune response with age and immunosenescence as an important mechanistic immune response to acute stressors. We examine the role of the gastrointestinal microbiome, age-related dysbiosis, and the integrated stress response in modulating the inflammatory "response" to damage accumulation and stress. We conclude by focusing on the seminal question of whether reducing inflammation is useful and the results of related clinical trials. In summary, we propose that inflammation may be viewed both as a clinical biomarker of the failure of resilience mechanisms and as a causal factor in the rising burden of disease and disabilities with aging. The fact that inflammation can be reduced through nonpharmacological interventions such as diet and exercise suggests that a life course approach based on education may be a successful strategy to increase the health span with few adverse consequences.

Translational Frontiers and Clinical Opportunities of Immunologically Fitted Radiotherapy

Ionizing radiation can have a wide range of impacts on tumor-immune interactions, which are being studied with the greatest interest and at an accelerating pace by the medical community. Despite its undeniable immunostimulatory potential, it clearly appears that radiotherapy as it is prescribed and delivered nowadays often alters the host's immunity toward a suboptimal state. This may impair the full recovery of a sustained and efficient antitumor immunosurveillance posttreatment. An emerging concept is arising from this awareness and consists of reconsidering the way of designing radiation treatment planning, notably by taking into account the individualized risks of deleterious radio-induced immune alteration that can be deciphered from the planned beam trajectory through lymphocyte-rich organs. In this review, we critically appraise key aspects to consider while planning immunologically fitted radiotherapy, including the challenges linked to the identification of new dose constraints to immune-rich structures. We also discuss how pharmacologic immunomodulation could be advantageously used in combination with radiotherapy to compensate for the radio-induced loss, for example, with (i) agonists of interleukin (IL)2, IL4, IL7, IL9, IL15, or IL21, similarly to G-CSF being used for the prophylaxis of severe chemo-induced neutropenia, or with (ii) myeloid-derived suppressive cell blockers.

The role of CD56bright NK cells in neurodegenerative disorders

Emerging evidence suggests a potential role for natural killer (NK) cells in neurodegenerative diseases, such as multiple sclerosis, Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. However, the precise function of NK cells in these diseases remains ambiguous. The existence of two NK cell subsets, CD56bright and CD56dim NK cells, complicates the understanding of the contribution of NK cells in neurodegeneration as their functions within the context of neurodegenerative diseases may differ significantly. CD56bright NK cells are potent cytokine secretors and are considered more immunoregulatory and less terminally differentiated than their mostly cytotoxic CD56dim counterparts. Hence, this review focusses on NK cells, specifically on CD56bright NK cells, and their role in neurodegenerative diseases. Moreover, it explores the mechanisms underlying their ability to enter the central nervous system. By consolidating current knowledge, we aim to provide a comprehensive overview on the role of CD56bright NK cells in neurodegenerative diseases. Elucidating their impact on neurodegeneration may have implications for future therapeutic interventions, potentially ameliorating disease pathogenesis.

A narrative review on inflammaging and late-onset hypogonadism

The increasing life expectancy observed in recent years has resulted in a higher prevalence of late-onset hypogonadism (LOH) in older men. LOH is characterized by the decline in testosterone levels and can have significant impacts on physical and mental health. While the underlying causes of LOH are not fully understood, there is a growing interest in exploring the role of inflammaging in its development. Inflammaging is a concept that describes the chronic, low-grade, systemic inflammation that occurs as a result of aging. This inflammatory state has been implicated in the development of various age-related diseases. Several cellular and molecular mechanisms have been identified as contributors to inflammaging, including immune senescence, cellular senescence, autophagy defects, and mitochondrial dysfunction. Despite the extensive research on inflammaging, its relationship with LOH has not yet been thoroughly reviewed in the literature. To address this gap, we aim to review the latest findings related to inflammaging and its impact on the development of LOH. Additionally, we will explore interventions that target inflammaging as potential treatments for LOH.

Relative expression of receptors in uterine natural killer cells compared to peripheral blood natural killer cells

One would expect maternal immune cells to attack the invading trophoblast as the placenta is semi-allogenic. However, they appear to cooperate with the trophoblast in disrupting the arterial wall which has been determined in several studies. uNK cells are a particular type of immune cell that appears to play a role in pregnancy. As in pregnancy, the key contributors to trophoblast invasion appear to be a unique combination of genes, which appear to regulate multiple components of the interactions between placental and maternal cells, called HLA class 1b genes. The HLA class 1b genes have few alleles, which makes them unlikely to be recognized as foreign by the maternal cells. The low polymorphic properties of these particular HLAs may aid trophoblasts in actively avoiding immune attacks. This review gives a complete description of the mechanisms of interaction between HLAs and maternal uNK cells in humans.

Co-expression of receptor tyrosine kinases and CD8 T-lymphocyte genes is associated with distinct prognoses, immune cell infiltration patterns and immunogenicity in cancers

Tumor angiogenesis and the immune microenvironment are 2 essential aspects of the tumor microenvironment (TME). The combination of receptor tyrosine kinase (RTK) inhibitor (TKI)-mediated antiangiogenic therapy and CD8 T-lymphocyte-mediated immunotherapy has become an important focus of cancer treatment, with good results for many tumor types. However, the complex regulatory interactions between these 2 treatment strategies have not been elucidated. Therefore, we systematically investigated the association between the RTKs and CD8 T-lymphocyte genes (CD8Ts) across cancers. We comprehensively evaluated alterations in RTK genes across cancers and examined the co-expression of RTKs and CD8Ts using a weighted gene co-expression network analysis. We found that RTKs exhibited extensive genetic alterations across cancers and were significantly related to the activity of cancer hallmark-related pathways. We identified co-expression between the RTKs and CD8Ts. The low co-expression score subtype was associated with significant better clinical benefits and was characterized by a hot immune microenvironment, including more infiltrating immune cells, higher chemokine expression, and stronger immunogenicity, such as the tumor mutation burden and neoantigens. Two immunotherapy cohorts confirmed that patients with low co-expression scores had an inflamed TME phenotype and significant therapeutic advantages. Then, 4 co-expression patterns were identified, with different patterns reflecting different prognoses and immune microenvironments. The RTK^lowCD8T^high group was associated with the best prognosis and immune-activated microenvironment. In summary, the present study indicates co-expression of RTKs and CD8Ts, which supports the potential application of the combination of inhibiting RTKs activity via TKI-targeted therapy and increasing CD8 T cell activity via immunotherapy in the treatment of cancer.

A missense variant in the nuclear localization signal of DKC1 causes Hoyeraal-Hreidarsson syndrome

Hoyeraal-Hreidarsson syndrome (HHS) is the most severe form of dyskeratosis congenita (DC) and is caused by mutations in genes involved in telomere maintenance. Here, we identified male siblings from a family with HHS carrying a hemizygous mutation (c.1345C > G, p.R449G), located in the C-terminal nuclear localization signal (NLS) of the DKC1 gene. These patients exhibit progressive cerebellar hypoplasia, recurrent infections, pancytopenia due to bone marrow failure, and short leukocyte telomere lengths. Single-cell RNA sequencing analysis suggested defects in the NLRP3 inflammasome in monocytes and the activation and maturation of NK cells and B cells. In experiments using induced pluripotent stem cells (iPSCs) from patients, DKC1_R449G iPSCs had short telomere lengths due to reduced levels of human telomerase RNA (hTR) and increased cytosolic proportions of DKC1. Treatment with dihydroquinolizinone RG7834 and 3'deoxyanosine cordycepin rescued telomere length in patient-derived iPSCs. Together, our findings not only provide new insights into immunodeficiency in DC patients but also provide treatment options for telomerase insufficiency disorders.

Transcriptomic profiling of adjuvant colorectal cancer identifies three key prognostic biological processes and a disease specific role for granzyme B

Background

Colorectal cancer (CRC) is a leading cause of cancer-related deaths, with a 5% 5-year survival rate for metastatic disease, yet with limited therapeutic advancements due to insufficient understanding of and inability to accurately capture high-risk CRC patients who are most likely to recur. We aimed to improve high-risk classification by identifying biological pathways associated with outcome in adjuvant stage II/III CRC.

Methods and findings

We included 1062 patients with stage III or high-risk stage II colon carcinoma from the prospective three-arm randomized phase 3 AVANT trial, and performed expression profiling to identify a prognostic signature. Data from validation cohort GSE39582, The Cancer Genome Atlas, and cell lines were used to further validate the prognostic biology. Our retrospective analysis of the adjuvant AVANT trial uncovered a prognostic signature capturing three biological functions—stromal, proliferative and immune—that outperformed the Consensus Molecular Subtypes (CMS) and recurrence prediction signatures like Oncotype Dx in an independent cohort. Importantly, within the immune component, high granzyme B (GZMB) expression had a significant prognostic impact while other individual T-effector genes were less or not prognostic. In addition, we found GZMB to be endogenously expressed in CMS2 tumor cells and to be prognostic in a T cell independent fashion. A limitation of our study is that these results, although robust and derived from a large dataset, still need to be clinically validated in a prospective study.

Conclusions

This work furthers our understanding of the underlying biology that propagates stage II/III CRC disease progression and provides scientific rationale for future high-risk stratification and targeted treatment evaluation in biomarker defined subpopulations of resectable high-risk CRC. Our results also shed light on an alternative GZMB source with context-specific implications on the disease’s unique biology.

CXCL8 is a prognostic biomarker and correlated with TNBC brain metastasis and immune infiltration

Patients with TNBC are associated with an increased risk of developing brain metastasis and shortest median survival post-brain metastasis-diagnosis. However, the regulatory mechanism of TNBC brain metastasis has not been addressed. Here, by a series of integrated analyses of differential gene expression profile from brain metastases and primary triple negative breast cancer, we identified 15 differentially expressed genes in both TNBC brain metastasis tissue samples and TNBC brain metastasis cell line. After analyzing the prognostic value of those 15 differentially expressed genes, we found that CXCL8 was the only gene associated with multiple prognostic indicators in both all-breast cancer and TNBC populations. Functional and pathway enrichment analyses demonstrated that CXCL8 was associated with humoral immune response and immune cell infiltration. CXCL8 expression had a positive correlation with three immune-related scores (ImmuneScore, ESTIMATEScore and StromalScore), and multiple types of immune cell infiltration, including macrophages, neutrophils and Th1 cells. Besides, we also verified the prometastatic effect of CXCL8, by treating MDA-MB-231 and Hs578t cells with different concentrations of recombinant human CXCL8. Taken together, our results suggest that CXCL8 can be used as a prognostic biomarker and is associated with TNBC brain metastasis and immune infiltration. Our findings provide a new perspective on TNBC brain metastasis and illustrate great potential to develop new CXCL8-targeted therapy for clinical TNBC patients.

A detailed analysis of innate and adaptive immune responsiveness upon infection with Salmonella enterica serotype Enteritidis in young broiler chickens

Salmonella enterica serotype Enteritidis (SE) is a zoonotic pathogen which causes foodborne diseases in humans as well as severe disease symptoms in young chickens. More insight in innate and adaptive immune responses of chickens to SE infection is needed to understand elimination of SE. Seven-day-old broiler chickens were experimentally challenged with SE and numbers and responsiveness of innate and adaptive immune cells as well as antibody titers were assessed. SE was observed in the ileum and spleen of SE-infected chickens at 7 days post-infection (dpi). At 1 dpi numbers of intraepithelial cytotoxic CD8⁺ T cells were significantly increased alongside numerically increased intraepithelial IL-2Rα⁺ and 20E5⁺ natural killer (NK) cells at 1 and 3 dpi. At both time points, activation of intraepithelial and splenic NK cells was significantly enhanced. At 7 dpi in the spleen, presence of macrophages and expression of activation markers on dendritic cells were significantly increased. At 21 dpi, SE-induced proliferation of splenic CD4⁺ and CD8⁺ T cells was observed and SE-specific antibodies were detected in sera of all SE-infected chickens. In conclusion, SE results in enhanced numbers and activation of innate cells and we hypothesized that in concert with subsequent specific T cell and antibody responses, reduction of SE is achieved. A better understanding of innate and adaptive immune responses important in the elimination of SE will aid in developing immune-modulation strategies, which may increase resistance to SE in young broiler chickens.

TERT Mutation Is Accompanied by Neutrophil Infiltration and Contributes to Poor Survival in Isocitrate Dehydrogenase Wild-Type Glioma

Mutation of the telomerase reverse transcriptase (TERT) promoter has been demonstrated as an unfavorable prognostic marker in patients with isocitrate dehydrogenase wild-type (IDHwt) glioma. This study aimed to investigate the immune role of TERT promoter mutation status which could improve prognostic prediction in IDHwt. TERT mutation status, IDH mutation, and 1p-19q codeletion status data were obtained from 614 glioma cases from the Cancer Genome Atlas, and 325 cases from the Chinese Glioma Genome Atlas. The same information was obtained from 49 clinical glioma tissues. TERT mutation is preferentially present in glioblastoma and IDH-wt gliomas and is associated with poor prognosis. Moreover, TERT mutation was associated with infiltration of neutrophils and expression of neutrophil chemokines. which might partially contribute to the poor outcome in IDH-wt glioma. Furthermore, patients with IDH-wt glioma did not harbor increased peripheral neutrophils, implying that the infiltrated neutrophil in the tumor environment might due to cytokine chemotaxis. In this study, we hereby propose that TERT mutation might be a molecular driver of the dysfunctional immune microenvironment in IDH-wt glioma. TERT mutation may be a potential immune therapeutic target for optimizing treatment combinations and patient selection for glioma immunotherapy.

PD-L1-Mediated Immunosuppression in Glioblastoma Is Associated With the Infiltration and M2-Polarization of Tumor-Associated Macrophages

There has been no significant improvements for immune checkpoint inhibitors since its first use. Tumour-associated macrophages (TAMs) are critical mediators in the PD-1/PD-L1 axis, contributing to the immunosuppressive tumour microenvironment. This study aims to investigate the potential role of PD-L1 in regulating TAMs in glioblastoma. Gene expression data and clinical information of glioma patients were collected from TCGA (n = 614) and CGGA (n = 325) databases. Differentially expressed genes between PD-L1^high and PD-L1^low groups were identified and subjected to bioinformatical analysis. We found that PD-L1 was frequently expressed in gliomas with a grade-dependent pattern. Higher PD-L1 expression predicted shorter overall survival. Moreover, PD-L1 was positively correlated with immunosuppressive cells (macrophage, neutrophil and immature DC) and negatively correlated with cytocidal immune cells (CD8⁺ T cell and Th1). Importantly, PD-L1 high expression was significantly correlated with M2-polarization of macrophages (M2-TAMs). We conclude that PD-L1 is an unfavourable prognostic marker for patients with glioblastoma; PD-L1-mediated immunosuppression may attribute to the infiltration and M2-polarization of TAMs.

CD56bright Natural Killer Cells: A Possible Biomarker of Different Treatments in Multiple Sclerosis

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system, which leads, in many cases, to irreversible disability. More than 15 disease-modifying treatments (DMTs) are available for the treatment of MS. Clinical activity or activity at magnetic resonance imaging (MRI) are now used to assess the efficacy of DMTs, but are negative prognostic factors per se. Therefore, a biomarker permitting us to identify patients who respond to treatment before they develop clinical/radiological signs of MS activity would be of high importance. The number of circulating CD56^bright natural killer (NK) cells may be such a biomarker. CD56^bright NK cells are a regulatory immune population belonging to the innate immune system. The number of CD56^bright NK cells increases upon treatment with interferon-beta, alemtuzumab, dimethyl fumarate, after autologous hematopoietic stem cell transplantation, and is higher in those who respond to fingolimod. In some cases, an increased number of CD56^bright NK cells is associated with an increase in their regulatory function. In the current review, we will evaluate the known effect on CD56^bright NK cells of DMTs for MS, and will discuss their possible role as a biomarker for treatment response in MS.

Surface protein imputation from single cell transcriptomes by deep neural networks

While single cell RNA sequencing (scRNA-seq) is invaluable for studying cell populations, cell-surface proteins are often integral markers of cellular function and serve as primary targets for therapeutic intervention. Here we propose a transfer learning framework, single cell Transcriptome to Protein prediction with deep neural network (cTP-net), to impute surface protein abundances from scRNA-seq data by learning from existing single-cell multi-omic resources.

Heterogeneity of human bone marrow and blood natural killer cells defined by single-cell transcriptome

Natural killer (NK) cells are critical to both innate and adaptive immunity. However, the development and heterogeneity of human NK cells are yet to be fully defined. Using single-cell RNA-sequencing technology, here we identify distinct NK populations in human bone marrow and blood, including one population expressing higher levels of immediate early genes indicative of a homeostatic activation. Functionally matured NK cells with high expression of CX3CR1, HAVCR2 (TIM-3), and ZEB2 represents terminally differentiated status with the unique transcriptional profile. Transcriptomic and pseudotime analyses identify a transitional population between CD56^bright and CD56^dim NK cells. Finally, a donor with GATA2^T354M mutation exhibits reduced percentage of CD56^bright NK cells with altered transcriptome and elevated cell death. These data expand our understanding of the heterogeneity and development of human NK cells.

Natural killer (NK) cells are important innate immune cells with diverse functions. Here the authors use single-cell RNA-sequencing of purified human bone marrow and peripheral blood NK cells to define five populations of NK cells with distinct transcriptomic profile to further our understanding of NK development and heterogeneity.

Immunosenescence: A systems-level overview of immune cell biology and strategies for improving vaccine responses

Immunosenescence contributes to a decreased capacity of the immune system to respond effectively to infections or vaccines in the elderly. The full extent of the biological changes that lead to immunosenescence are unknown, but numerous cell types involved in innate and adaptive immunity exhibit altered phenotypes and function as a result of aging. These manifestations of immunosenescence at the cellular level are mediated by dysregulation at the genetic level, and changes throughout the immune system are, in turn, propagated by numerous cellular interactions. Environmental factors, such as nutrition, also exert significant influence on the immune system during aging. While the mechanisms that govern the onset of immunosenescence are complex, systems biology approaches allow for the identification of individual contributions from each component within the system as a whole. Although there is still much to learn regarding immunosenescence, systems-level studies of vaccine responses have been highly informative and will guide the development of new vaccine candidates, novel adjuvant formulations, and immunotherapeutic drugs to improve vaccine responses among the aging population.

Characterization of human natural killer cells for therapeutic use

As a part of the innate immune system, natural killer (NK) cells are cytotoxic lymphocytes that can exert cytotoxic activity against infected or transformed cells. Furthermore, due to their expression of a functional Fc receptor, they have also been eluded as a major effector fraction in antibody-dependent cellular cytotoxicity. These characteristics have led to multiple efforts to use them for adoptive immunotherapy against various malignancies.  There are now at least 70 clinical trials testing the safety and efficacy of NK cell products around the world in early-phase clinical trials. NK cells are also being tested in the context of tumor retargeting via chimeric antigen receptors, other genetic modification strategies, as well as tumor-specific activation strategies such as bispecific engagers with or without cytokine stimulations. One advantage of the use of NK cells for adoptive immunotherapy is their potential to overcome HLA barriers. This has led to a plethora of sources, such as cord blood hematopoietic stem cells and induced pluripotent stem cells, which can generate comparatively high cytotoxic NK cells to peripheral blood counterparts. However, the variety of the sources has led to a heterogeneity in the characterization of the final infusion product. Therefore, in this review, we will discuss a comparative assessment strategy, from characterization of NK cells at collection to final product release by various phenotypic and functional assays, in an effort to predict potency of the cellular product.

Abnormalities of quantities and functions of CD56bright natural killer cells in non-severe aplastic Anemia

OBJECTIVES

The mechanism of non-severe aplastic anemia (NSAA) is not clear. It may be different from severe aplastic anemia (SAA). CD56bright NK cells (regulatory NK cells) is a subgroup of NK cells that produce immunoregulatory cytokines and express high-affinity IL-2 receptor. To investigate CD56bright NK cells quantities and function in patients with NSAA and to explore how CD56bright NK cells participate in the progress of this disease.

METHODS

In this study, we analyzed the quantitative and functional changes of CD56bright NK cells in peripheral blood of patients with NSAA by using Flow Cytometry (FCM) before and after immunosuppressive therapy (IST). The expressions of activating receptor (NKG2D, NKp46, NKp44), inhibitory receptor (NKG2A, CD158a, CD158b) and perforin and granzyme B were detected by FCM. IL-2 and IL-18 levels in serum were detected by ELISA. The correlation between these parameters and clinical indicators of patients were evaluated.

RESULTS

We found that the percentage of CD56bright NK cells in newly diagnosed NSAA patients was higher than that in normal controls (p = .011, p < .05). The median expression of NKG2D in patients with NSAA was higher compared to that in normal controls (p = .021, p < .05), and the expression of CD158a was lower (p = .047, p < .05). The concentrations of IL-2 and IL-18 in the serum of patients with NSAA were higher than those in normal group.

CONCLUSION

These findings suggest that increased and activated CD56bright NK cells might play a protective role in the pathogenesis of NSAA.

CD56bright natural killer cells exhibit abnormal phenotype and function in severe aplastic anemia

INTRODUCTION

CD56^bright NK cells have been highlighted to serve immunoregulatory functions. However, their roles in severe aplastic anemia (SAA) have not been elucidated.

METHODS

Here, we investigated the quantities, phenotypes, cytokine secretion abilities, and the cytotoxicities of peripheral CD56^bright NK cells along with CD56^dim NK cells obtained from patients with SAA, SAA in remission (R-SAA), and healthy controls (HC).

RESULTS

We observed the decreased quantities of CD56^bright NK cells in SAA compared with in R-SAA and HC. In SAA, the quantities of CD56^bright NK cells correlated with the disease severity. Activating receptors NKp46 and NKp44 on CD56^bright NK cells were upregulated while inhibiting receptor NKG2A was downregulated in SAA. CD56^bright NK cells obtained from SAA patients produced increased IL-10 and decreased IFN-γ in vitro compared with cells obtained from HC, while TNF-α and IL-13 productions were not different between two groups. Under a 7-day prestimulation with IL-2 and IL-12, the serum concentrations of which were higher in SAA patients, CD56^bright NK obtained from HC also produced increased IL-10 mRNAs. There were no differences of cytotoxicites between CD56^bright NK cells in SAA and in HC.

CONCLUSION

We discovered that CD56^bright NK cells exhibited abnormal receptor expressions and cytokine production in SAA, and they were related with the severity of illness.

Gene Regulatory Programs Conferring Phenotypic Identities to Human NK Cells

Natural killer (NK) cells develop from common progenitors but diverge into distinct subsets, which differ in cytokine production, cytotoxicity, homing, and memory traits. Given their promise in adoptive cell therapies for cancer, a deeper understanding of regulatory modules controlling clinically beneficial NK phenotypes is of high priority. We report integrated "-omics" analysis of human NK subsets, which revealed super-enhancers associated with gene cohorts that may coordinate NK functions and localization. A transcription factor-based regulatory scheme also emerged, which is evolutionarily conserved and shared by innate and adaptive lymphocytes. For both NK and T lineages, a TCF1-LEF1-MYC axis dominated the regulatory landscape of long-lived, proliferative subsets that traffic to lymph nodes. In contrast, effector populations circulating between blood and peripheral tissues shared a PRDM1-dominant landscape. This resource defines transcriptional modules, regulated by feedback loops, which may be leveraged to enhance phenotypes for NK cell-based therapies.

CD56bright cells respond to stimulation until very advanced age revealing increased expression of cellular protective proteins SIRT1, HSP70 and SOD2

BACKGROUND

NK cells are cytotoxic lymphocytes of innate immunity composed of: cytotoxic CD56dim and immunoregulatory CD56bright cells. The study aimed to analyze the expression of cellular protective proteins: sirtuin 1 (SIRT1), heat shock protein 70 (HSP70) and manganese superoxide dismutase (SOD2) in CD56dim and CD56bright NK cells of the young, seniors aged under 85 ('the old') and seniors aged over 85 ('the oldest'). We studied both non-stimulated NK cells and cells stimulated by IL-2, LPS or PMA with ionomycin. The expression level of proinflammatory cytokines TNF and IFN-γ was also assessed in NK cell subsets and some relationships between the studied parameters were analyzed.

RESULTS

CD56bright cells showed sensitivity to most of the applied stimulatory agents until very advanced age in regards to the expression of SIRT1 and intracellular HSP70. On the contrary, CD56dim cells, sensitive to stimulation by most of the stimulatory agents in the young and the old, in the oldest lost this sensitivity and presented rather high, constant expression of SIRT1 and HSP70, resistant to further stimulation. With reference to SOD2 expression, CD56dim cells were insensitive to stimulation in the young, but their sensitivity increased with ageing. CD56bright cells were sensitive to most of the applied agents in the young and the old but in the oldest they responded to all of the stimulatory agents used in the study. Similarly, both NK cell subsets were sensitive to stimulation until very advanced age in regards to the expression of TNF and IFN-γ.

CONCLUSIONS

CD56bright cells maintained sensitivity to stimulation until very advanced age presenting also an increased expression of SIRT1 and HSP70. CD56dim cells showed a constantly increased expression of these cellular protective proteins in the oldest, insensitive for further stimulation. The oldest, however, did not reveal an increased level of SOD2 expression, but it was significantly elevated in both NK cell subsets after stimulation.The pattern of expression of the studied cellular protective proteins in ageing process revealed the adaptation of NK cells to stress response in the oldest seniors which might accompany the immunosenescence and contribute to the long lifespan of this group of the elderly.

Ginsenoside F1 Promotes Cytotoxic Activity of NK Cells via Insulin-Like Growth Factor-1-Dependent Mechanism

Ginsenosides are the principal active components of ginseng and are considered attractive candidates for combination cancer therapy because they can kill tumors and have favorable safety profiles. However, the overall benefit of ginsenosides remains unclear, particularly in cancer immunosurveillance, considering the controversial results showing repression or promotion of immune responses. Here we identify a potentiating role of ginsenoside F1 (G-F1) in cancer surveillance by natural killer (NK) cells. Among 15 different ginsenosides, G-F1 most potently enhanced NK cell cytotoxicity in response to diverse activating receptors and cancer cells. G-F1 also improved cancer surveillance in mouse models of lymphoma clearance and metastatic melanoma that rely on NK cell activity. G-F1-treated NK cells exhibited elevated cytotoxic potential such as upregulation of cytotoxic mediators and of activation signals upon stimulation. NK cell potentiation by G-F1 was antagonized by insulin-like growth factor (IGF)-1 blockade and recapitulated by IGF-1 treatment, suggesting the involvement of IGF-1. Thus, our results suggest that G-F1 enhances NK cell function and may have chemotherapeutic potential in NK cell-based immunotherapy. We anticipate our results to be a starting point for further comprehensive studies of ginsenosides in the immune cells mediating cancer surveillance and the development of putative therapeutics.

Enhancing the Activation and Releasing the Brakes: A Double Hit Strategy to Improve NK Cell Cytotoxicity Against Multiple Myeloma

Natural killer (NK) cells are innate lymphocytes with a strong antitumor ability. In tumor patients, such as multiple myeloma (MM) patients, an elevated number of NK cells after stem cell transplantation (SCT) has been reported to be correlated with a higher overall survival rate. With the aim of improving NK cell use for adoptive cell therapy, we also addressed the cytotoxicity of patient-derived, cytokine-stimulated NK cells against MM cells at specific time points: at diagnosis and before and after autologous stem cell transplantation. Remarkably, after cytokine stimulation, the patients' NK cells did not significantly differ from those of healthy donors. In a small cohort of MM patients, we were able to isolate autologous tumor cells, and we could demonstrate that IL-2/15 stimulated autologous NK cells were able to significantly improve their killing capacity of autologous tumor cells. With the aim to further improve the NK cell killing capacity against MM cells, we investigated the potential use of NK specific check point inhibitors with focus on NKG2A because this inhibitory NK cell receptor was upregulated following ex vivo cytokine stimulation and MM cells showed HLA-E expression that could even be increased by exposure to IFN-γ. Importantly, blocking of NKG2A resulted in a significant increase in the NK cell-mediated lysis of different MM target cells. Finally, these results let suggest that combining cytokine induced NK cell activation and the specific check point inhibition of the NKG2A-mediated pathways can be an effective strategy to optimize NK cell therapeutic approaches for treatment of multiple myeloma.

ISG20 promotes local tumor immunity and contributes to poor survival in human glioma

Recent evidence has confirmed that a mutation of the isocitrate dehydrogenase (IDH) gene occurs early in gliomagenesis and contributes to suppressed immunity. The present study aimed to determine the candidate genes associated with IDH mutation status that could serve as biomarkers of immune suppression for improved prognosis prediction. Clinical information and RNA-seq gene expression data were collected for 932 glioma samples from the CGGA and TCGA databases, and differentially expressed genes in both lower-grade glioma (LGG) and glioblastoma (GBM) samples were identified according to IDH mutation status. Only one gene, interferon-stimulated exonuclease gene 20 (ISG20), with reduced expression in IDH mutant tumors, demonstrated significant prognostic value. ISG20 expression level significantly increased with increasing tumor grade, and its high expression was associated with a poor clinical outcome. Moreover, increased ISG20 expression was associated with increased infiltration of monocyte-derived macrophages and neutrophils, and suppressed adaptive immune response. ISG20 expression was also positively correlated with PD-1, PD-L1, and CTLA4 expression, along with the levels of several chemokines. We conclude that ISG20 is a useful biomarker to identify IDH-mediated immune processes in glioma and may serve as a potential therapeutic target.

New miRNA Signature Heralds Human NK Cell Subsets at Different Maturation Steps: Involvement of miR-146a-5p in the Regulation of KIR Expression

Natural killer cells are cytotoxic innate lymphoid cells that play an important role for early host defenses against infectious pathogens and surveillance against tumor. In humans, NK cells may be divided in various subsets on the basis of the relative CD56 expression and of the low-affinity FcγRIIIA CD16. In particular, the two main NK cell subsets are represented by the CD56^bright/CD16^−/dim and the CD56^dim/CD16^bright NK cells. Experimental evidences indicate that CD56^bright and CD56^dim NK cells represent different maturative stages of the NK cell developmental pathway. We identified multiple miRNAs differentially expressed in CD56^bright/CD16⁻ and CD56^dim/CD16^bright NK cells using both univariate and multivariate analyses. Among these, we found a few miRNAs with a consistent differential expression in the two NK cell subsets, and with an intermediate expression in the CD56^bright/CD16^dim NK cell subset, representing a transitional step of maturation of NK cells. These analyses allowed us to establish the existence of a miRNA signature able to efficiently discriminate the two main NK cell subsets regardless of their surface phenotype. In addition, by analyzing the putative targets of representative miRNAs we show that hsa-miR-146a-5p, may be involved in the regulation of killer Ig-like receptor (KIR) expression. These results contribute to a better understanding of the physiologic significance of miRNAs in the regulation of the development/function of human NK cells. Moreover, our results suggest that hsa-miR-146a-5p targeting, resulting in KIR down-regulation, may be exploited to generate/increment the effect of NK KIR-mismatching against HLA-class I⁺ tumor cells and thus improve the NK-mediated anti-tumor activity.

Innate-like CD8+ T-cells and NK cells: converging functions and phenotypes

New data in the worlds of both innate-like CD8+ T-cells and natural killer (NK) cells have, in parallel, clarified some of the phenotypes of these cells and also their associated functions. While these cells are typically viewed entirely separately, the emerging innate functions of T-cells and, similarly, the adaptive functions of NK cells suggest that many behaviours can be considered in parallel. In this review we compare the innate functions of CD8+ T-cells (especially mucosal-associated invariant T-cells) and those of NK cells, and how these relate to expression of phenotypic markers, especially CD161 and CD56.

NK cells of the oldest seniors represent constant and resistant to stimulation high expression of cellular protective proteins SIRT1 and HSP70

Background

Natural killer cells (NK cells) are cytotoxic lymphocytes of innate immunity that reveal some immunoregulatory properties, however, their role in the process of ageing is not completely understood. The study aimed to analyze the expression of proteins involved in cellular stress response: sirtuin 1 (SIRT1), heat shock protein 70 (HSP70) and manganese superoxide dismutase (SOD2) in human NK cells with reference to the process of ageing. Non-stimulated and stimulated with IL-2, LPS or PMA with ionomycin cells originated from peripheral blood samples of: seniors aged over 85 (‘the oldest’; n = 25; 88.5 ± 0.5 years, mean ± SEM), seniors aged under 85 (‘the old’; n = 30; 75.6 ± 0.9 years) and the young (n = 31; 20.9 ± 0.3 years). The relationships between the levels of expression of cellular protective proteins in the studied population were also analyzed. The concentrations of carbonyl groups and 8-isoprostanes, markers of oxidative stress, in both stimulated and non-stimulated cultured NK cells were measured to assess the level of the oxidative stress in the cells.

Results

The oldest seniors varied from the other age groups by significantly higher expression of SIRT1 and HSP70 both in non-stimulated and stimulated NK cells. These cells also appeared to be resistant to further stimulations with IL-2, LPS or PMA with ionomycin. Highly positive correlations between SIRT1 and intracellular HSP70 in both stimulated and non-stimulated NK cells were observed. SOD2 presented low expression in non-stimulated cells, whereas its sensitivity to stimulation increased with age of donors. High positive correlations between SOD2 and surface HSP70 were observed. We found that the markers of oxidative stress in NK cells did not change with ageing.

Conclusions

The oldest seniors revealed well developed adaptive stress response in NK cells with increased, constant levels of SIRT1 and intracellular HSP70. They presented also very high positive correlations between expression of these cellular protective proteins both in stimulated and non-stimulated cells. These phenomena may contribute to the long lifespan of this group of elderly. Interestingly, in NK cells SOD2 revealed a distinct role in cellular stress response since it showed sensitivity to stimulation increasing with age of participants. These observations provide novel data concerning the role of NK cells in the process of ageing.

Enhancement of mammary tumour growth by IGFBP-3 involves impaired T cell accumulation

Epidemiological studies show an association between obesity and poor breast cancer prognosis. We previously demonstrated that global IGFBP-3 deficiency, in IGFBP-3-null mice, resulted in a 50% reduction in mammary tumour growth over 3 weeks relative to tumours in wild-type (WT) C57BL/6 mice. This growth reduction was ameliorated by high fat feeding-induced obesity. This study aimed to examine how IGFBP-3 promotes tumour growth by influencing the immune tumour microenvironment in healthy and obese mice. Syngeneic EO771 cells, which lack detectable IGFBP-3 expression, were grown as orthotopic tumours in WT and IGFBP-3-null C57BL/6 mice placed on either a control chow or a high-fat diet (HFD), and examined by quantitative PCR and immunohistochemistry. In WT mice, increased stromal expression of IGFBP-3 was positively associated with tumour growth, supporting the hypothesis that IGFBP-3 in the microenvironment promotes tumour progression. Examining markers of immune cell subsets, gene expression of Ifng, Cd8a, Cd8b1 and Tnf and CD8 measured by immunohistochemistry were elevated in tumours of IGFBP-3-null mice compared to WT, indicating an accumulation of CD8+ T cells, but this increase was absent if the IGFBP-3-null mice had been exposed to HFD. Expression of these genes was negatively associated with tumour growth. Although similar among groups overall, Nkg2d and Tnfsf10 tumoural expression was associated with decreased tumour growth. Overall, the results of this study provide an immune-based mechanism by which host IGFBP-3 may promote breast tumour growth in the EO771 murine breast cancer model, and suggest that targeting IGFBP-3 might make a novel contribution to immune therapy for breast cancer.

Simultaneous epitope and transcriptome measurement in single cells

High-throughput single-cell RNA sequencing has transformed our understanding of complex cell populations, but it does not provide phenotypic information such as cell-surface protein levels. Here, we describe cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq), a method in which oligonucleotide-labeled antibodies are used to integrate cellular protein and transcriptome measurements into an efficient, single-cell readout. CITE-seq is compatible with existing single-cell sequencing approaches and scales readily with throughput increases.

Tumor immune microenvironment characterization in clear cell renal cell carcinoma identifies prognostic and immunotherapeutically relevant messenger RNA signatures

BACKGROUND

Tumor-infiltrating immune cells have been linked to prognosis and response to immunotherapy; however, the levels of distinct immune cell subsets and the signals that draw them into a tumor, such as the expression of antigen presenting machinery genes, remain poorly characterized. Here, we employ a gene expression-based computational method to profile the infiltration levels of 24 immune cell populations in 19 cancer types.

RESULTS

We compare cancer types using an immune infiltration score and a T cell infiltration score and find that clear cell renal cell carcinoma (ccRCC) is among the highest for both scores. Using immune infiltration profiles as well as transcriptomic and proteomic datasets, we characterize three groups of ccRCC tumors: T cell enriched, heterogeneously infiltrated, and non-infiltrated. We observe that the immunogenicity of ccRCC tumors cannot be explained by mutation load or neo-antigen load, but is highly correlated with MHC class I antigen presenting machinery expression (APM). We explore the prognostic value of distinct T cell subsets and show in two cohorts that Th17 cells and CD8+ T/Treg ratio are associated with improved survival, whereas Th2 cells and Tregs are associated with negative outcomes. Investigation of the association of immune infiltration patterns with the subclonal architecture of tumors shows that both APM and T cell levels are negatively associated with subclone number.

CONCLUSIONS

Our analysis sheds light on the immune infiltration patterns of 19 human cancers and unravels mRNA signatures with prognostic utility and immunotherapeutic biomarker potential in ccRCC.

Human Circulating and Tissue-Resident CD56(bright) Natural Killer Cell Populations

Two human natural killer (NK) cell subsets are usually distinguished, displaying the CD56^dimCD16⁺ and the CD56^brightCD16^−/+ phenotype. This distinction is based on NK cells present in blood, where the CD56^dim NK cells predominate. However, CD56^bright NK cells outnumber CD56^dim NK cells in the human body due to the fact that they are predominant in peripheral and lymphoid tissues. Interestingly, within the total CD56^bright NK cell compartment, a major phenotypical and functional diversity is observed, as demonstrated by the discovery of tissue-resident CD56^bright NK cells in the uterus, liver, and lymphoid tissues. Uterus-resident CD56^bright NK cells express CD49a while the liver- and lymphoid tissue-resident CD56^bright NK cells are characterized by co-expression of CD69 and CXCR6. Tissue-resident CD56^bright NK cells have a low natural cytotoxicity and produce little interferon-γ upon monokine stimulation. Their distribution and specific phenotype suggest that the tissue-resident CD56^bright NK cells exert tissue-specific functions. In this review, we examine the CD56^bright NK cell diversity by discussing the distribution, phenotype, and function of circulating and tissue-resident CD56^bright NK cells. In addition, we address the ongoing debate concerning the developmental relationship between circulating CD56^bright and CD56^dim NK cells and speculate on the position of tissue-resident CD56^bright NK cells. We conclude that distinguishing tissue-resident CD56^bright NK cells from circulating CD56^bright NK cells is a prerequisite for the better understanding of the specific role of CD56^bright NK cells in the complex process of human immune regulation.

Investigating the potential immune role of fish NCAMs: Molecular cloning and expression analysis in mandarin fish

The immune role of NCAMs has been revealed in mammals, yet there is no such report in fish. Hence, we analyzed the molecular characterizations and immune-associated expression patterns of NCAMs in mandarin fish. Three NCAM members, named mfNCAM1a, mfNCAM1b and mfNCAM2, were identified. Among the cDNA sequences of mfNCAMs, AU-rich elements in the 3' UTRs of mfNCAM1b and mfNCAM2 as well as VASE sequences in the fourth Ig-like domain-encoding regions of mfNCAM1a and mfNCAM1b were discovered. Moreover, the syntenic analysis suggested that the duplication of NCAM1 is fish-specific. At mRNA and protein levels, the expression analyses revealed that mfNCAMs existed in both systemic and mucosal immune tissues, and located within lymphoid cells. Upon stimulated either by LPS or poly I:C, the expression level of mfNCAM1a was significantly up-regulated in head kidney, spleen, liver, and gut, whereas mfNCAM1b only in head kidney and liver, and mfNCAM2 only in liver. Additionally, the cells coexpressed mfNCAM1 and mfNCCRP-1 might imply the equivalents to mammalian NK cells. Our finding firstly demonstrates the member-specific immune-related tissue expression pattern and immune activity for fish NCAMs. Current data indicate that mfNCAM2 has little immune activity, while the immune activity of mfNCAM1a exists in more tissues than mfNCAM1b, and mfNCAM1a may tend to respond more actively to viral while mfNCAM1b to bacterial stimulants. Additionally, NCAM1b should be a fish-specific member with unique immune function, judging from its different expression pattern, immune activity as well as phylogenetic relationship to mfNCAM1a.

B7-H6-mediated downregulation of NKp30 in NK cells contributes to ovarian carcinoma immune escape

In this study the phenotype and function of tumor-associated NK cells from peritoneal fluids of a selected cohort of patients with seropapillary ovarian carcinoma were analyzed. In > 50% of these patients, the expression of the activating receptor NKp30 in tumor-associated NK cells was substantially reduced as compared to autologous peripheral blood (PB) NK cells. The impaired expression of this receptor was associated with the presence of one of its cellular ligands (B7-H6), which was detectable as a surface/cytosolic molecule in tumor cells and as a soluble molecule in the peritoneal fluid. NK cells from patients expressing this NKp30low phenotype displayed an impaired interferon-gamma (IFNγ) production and cytolytic function when tested against target cells expressing surface B7-H6. Our data also suggest that in these patients, the defective expression and function of NKp30 may be induced by the chronic engagement of this receptor by soluble B7-H6 or by tumor cells expressing this ligand. The impairment of NK cell functions described herein could represent a novel mechanism by which the tumor microenvironment may contribute to the escape from immune surveillance.

Genomic expression profiling of NK cells in health and disease

NK cells are important components of innate and adaptive immunity. Functionally, they play key roles in host defense against tumors and infectious pathogens. Within the past few years, genomic-scale experiments have provided us with a plethora of gene expression data that reveal an extensive molecular and biological map underlying gene expression programs. In order to better explore and take advantage of existing datasets, we review here the genomic expression profiles of NK cells and their subpopulations in resting or stimulated states, in diseases, and in different organs; moreover, we contrast these expression data to those of other lymphocytes. We have also compiled a comprehensive list of genomic profiling studies of both human and murine NK cells in this review.

Spatiotemporal dynamics of intratumoral immune cells reveal the immune landscape in human cancer

The complex interactions between tumors and their microenvironment remain to be elucidated. Combining large-scale approaches, we examined the spatio-temporal dynamics of 28 different immune cell types (immunome) infiltrating tumors. We found that the immune infiltrate composition changed at each tumor stage and that particular cells had a major impact on survival. Densities of T follicular helper (Tfh) cells and innate cells increased, whereas most T cell densities decreased along with tumor progression. The number of B cells, which are key players in the core immune network and are associated with prolonged survival, increased at a late stage and showed a dual effect on recurrence and tumor progression. The immune control relevance was demonstrated in three endoscopic orthotopic colon-cancer mouse models. Genomic instability of the chemokine CXCL13 was a mechanism associated with Tfh and B cell infiltration. CXCL13 and IL21 were pivotal factors for the Tfh/B cell axis correlating with survival. This integrative study reveals the immune landscape in human colorectal cancer and the major hallmarks of the microenvironment associated with tumor progression and recurrence.

IGF-1 promotes the development and cytotoxic activity of human NK cells

Insulin-like growth factor 1 (IGF-1) is a critical regulator of many physiological functions, ranging from longevity to immunity. However, little is known about the role of IGF-1 in natural killer cell development and function. Here, we identify an essential role for IGF-1 in the positive regulation of human natural killer cell development and cytotoxicity. Specifically, we show that human natural killer cells have the ability to produce IGF-1 and that differential endogenous IGF-1 expression leads to disparate cytotoxicity in human primary natural killer cells. Moreover, miR-483-3p is identified as a critical regulator of IGF-1 expression in natural killer cells. Overexpression of miR-483-3p has an effect similar to IGF-1 blockade and decreased natural killer cell cytotoxicity, whereas inhibition of miR-483-3p has the opposite effect, which is reversible with IGF-1 neutralizing antibody. These findings indicate that IGF-1 and miR-483-3p belong to a new class of natural killer cell functional modulators and strengthen the prominent role of IGF-1 in innate immunity.

Insulin-like growth factor (IGF)-1 regulates many physiological functions including growth and metabolism. Ni et al. show that human natural killer cells secrete IGF-1 and that IGF-1 enhances the development and cytotoxicity of these cells.

Proteome analysis of distinct developmental stages of human natural killer (NK) cells

The recent Natural Killer (NK) cell maturation model postulates that CD34(+) hematopoietic stem cells (HSC) first develop into CD56(bright) NK cells, then into CD56(dim)CD57(-) and finally into terminally maturated CD56(dim)CD57(+). The molecular mechanisms of human NK cell differentiation and maturation however are incompletely characterized. Here we present a proteome analysis of distinct developmental stages of human primary NK cells, isolated from healthy human blood donors. Peptide sequencing was used to comparatively analyze CD56(bright) NK cells versus CD56(dim) NK cells and CD56(dim)CD57(-) NK cells versus CD56(dim)CD57(+) NK cells and revealed distinct protein signatures for all of these subsets. Quantitative data for about 3400 proteins were obtained and support the current differentiation model. Furthermore, 11 donor-independently, but developmental stage specifically regulated proteins so far undescribed in NK cells were revealed, which may contribute to NK cell development and may elucidate a molecular source for NK cell effector functions. Among those proteins, S100A4 (Calvasculin) and S100A6 (Calcyclin) were selected to study their dynamic subcellular localization. Upon activation of human primary NK cells, both proteins are recruited into the immune synapse (NKIS), where they colocalize with myosin IIa.

Impact of brief exercise on peripheral blood NK cell gene and microRNA expression in young adults

Natural killers (NK) cells are unique innate immune cells that increase up to fivefold in the circulating blood with brief exercise and are known to play a key role in first-response defense against pathogens and cancer immunosurveillance. Whether exercise alters NK cell gene and microRNA (miRNA) expression is not known. Thirteen healthy men (20-29 yr old) performed ten 2-min bouts of cycle ergometer exercise at a constant work equivalent to an average of 77% of maximum O2 consumption interspersed with 1-min rest. Blood was drawn before and immediately after the exercise challenge. NK cells were isolated from peripheral blood mononuclear cells using a negative magnetic cell separation method. We used Affymetrix U133+2.0 arrays for gene expression and Agilent Human miRNA V2 Microarray for miRNAs. A stringent statistical approach (false discovery rate < 0.05) was used to determine that exercise significantly altered the expression of 986 genes and 23 miRNAs. Using in silico analysis, we found exercise-related gene pathways where there was a high likelihood of gene-miRNA interactions. These pathways were predominantly associated with cancer and cell communication, including p53 signaling pathway, melanoma, glioma, prostate cancer, adherens junction, and focal adhesion. These data support the hypothesis that exercise affects the gene and miRNA expression pattern in the population of NK cells in the circulation and suggest mechanisms through which physical activity could alter health through the innate immune system.

NK cells in healthy aging and age-associated diseases

NK cells exhibit the highest cytotoxic capacity within the immune system. Alteration of their number or functionality may have a deep impact on overall immunity. This is of particular relevance in aging where the elderly population becomes more susceptible to infection, cancer, autoimmune diseases, and neurodegenerative diseases amongst others. As the fraction of elderly increases worldwide, it becomes urgent to better understand the aging of the immune system to prevent and cure the elderly population. For this, a better understanding of the function and phenotype of the different immune cells and their subsets is necessary. We review here NK cell functions and phenotype in healthy aging as well as in various age-associated diseases.

Ex vivo generated natural killer cells acquire typical natural killer receptors and display a cytotoxic gene expression profile similar to peripheral blood natural killer cells

Ex vivo differentiation systems of natural killer (NK) cells from CD34+ hematopoietic stem cells are of potential importance for adjuvant immunotherapy of cancer. Here, we analyzed ex vivo differentiation of NK cells from cord blood-derived CD34+ stem cells by gene expression profiling, real-time RT-PCR, flow cytometry, and functional analysis. Additionally, we compared the identified characteristics to peripheral blood (PB) CD56(bright) and CD56(dim) NK cells. The data show sequential expression of CD56 and the CD94 and NKG2 receptor chains during ex vivo NK cell development, resulting finally in the expression of a range of genes with partial characteristics of CD56(bright) and CD56(dim) NK cells from PB. Expression of characteristic NK cell receptors and cytotoxic genes was mainly found within the predominant ex vivo generated population of NKG2A+ NK cells, indicating the importance of NKG2A expression during NK cell differentiation and maturation. Furthermore, despite distinct phenotypic characteristics, the detailed analysis of cytolytic genes expressed within the ex vivo differentiated NK cells revealed a pattern close to CD56(dim) NK cells. In line with this finding, ex vivo generated NK cells displayed potent cytotoxicity. This supports that the ex vivo differentiation system faithfully reproduces major steps of the differentiation of NK cells from their progenitors, constitutes an excellent model to study NK cell differentiation, and is valuable to generate large-scale NK cells appropriate for immunotherapy.

Expression pattern of cathepsin W isoforms in peripheral blood and gastroesophageal mucosa of patients with gastroesophageal reflux disease

Cathepsin W is exclusively expressed in immune cells, and a novel isoform was identified previously. To characterize the expression pattern of the wildtype and isoform Ins10, specific polymerase chain reaction assays were generated and used to study respective transcript levels in peripheral blood cells and gastric biopsies in healthy subjects. The wildtype-encoding transcript levels were 3- and 9-fold higher in mucosal samples and peripheral immune cells, respectively (p<0.05). The predominant expression of wildtype form by infiltrating immune cells was confirmed in 116 patients with gastroesophageal reflux disease and 27 reflux-negative individuals demonstrating that cathepsin W expression is not altered in this disease.

Innate immunosenescence: effect of aging on cells and receptors of the innate immune system in humans

Components of the innate immune response, including neutrophils and macrophages, are the first line of defense against infections. Their role is to initiate an inflammatory response, phagocyte and kill pathogens, recruit natural killer cells (NK), and facilitate the maturation and migration of dendritic cells that will initiate the adaptive immune response. Extraordinary advances have been made in the last decade on the knowledge of the receptors and mechanisms used by cells of the innate immunity not only to sense and eliminate the pathogen but also to communicate each other and collaborate with cells of adaptive immunity to mount an effective immune response. The analysis of innate immunity in elderly humans has evidenced that aging has a profound impact on the phenotype and functions of these cells. Thus altered expression and/or function of innate immunity receptors and signal transduction leading to defective activation and decreased chemotaxis, phagocytosis and intracellular killing of pathogens have been described. The phenotype and function of NK cells from elderly individuals show significant changes that are compatible with remodeling of the different NK subsets, with a decrease in the CD56bright subpopulation and accumulation of the CD56dim cells, in particular those differentiated NK cells that co-express CD57, as well as a decreased expression of activating natural cytotoxicity receptors. These alterations can be responsible of the decreased production of cytokines and the lower per-cell cytotoxicity observed in the elderly. Considering the relevance of these cells in the initiation of the immune response, the possibility to reactivate the function of innate immune cells should be considered in order to improve the response to pathogens and to vaccination in the elderly.

Long-term proliferation of functional human NK cells, with conversion of CD56(dim) NK cells to a CD56 (bright) phenotype, induced by carcinoma cells co-expressing 4-1BBL and IL-12

4-1BB ligation co-stimulates T cell activation, and agonistic antibodies have entered clinical trials. Natural killer (NK) cells also express 4-1BB following activation and are implicated in the anti-tumour efficacy of 4-1BB stimulation in mice; however, the response of human NK cells to 4-1BB stimulation is not clearly defined. Stimulation of non-adherent PBMC with OVCAR-3 cells expressing 4-1BB ligand (4-1BBL) or IL-12 resulted in preferential expansion of the NK cell population, while the combination 4-1BBL + IL-12 was superior for the activation and proliferation of functional NK cells from healthy donors and patients with renal cell or ovarian carcinoma, supporting long-term (21 day) NK cell proliferation. The expanded NK cells are predominantly CD56(bright), and we show that isolated CD56(dim)CD16(+) NK cells can switch to a CD56(bright)CD16(-) phenotype and proliferate in response to 4-1BBL + IL-12. Whereas 4-1BB upregulation on NK cells in response to 4-1BBL required 'help' from other PBMC, it could be induced on isolated NK cells by IL-12, but only in the presence of target (OVCAR-3) cells. Following primary stimulation with OVCAR-3 cells expressing 4-1BBL + IL-12 and subsequent resting until day 21, NK cells remained predominantly CD56(bright) and retained both high cytotoxic capability against K562 targets and enhanced ability to produce IFNγ relative to NK cells in PBMC. These data support the concept that NK cells could contribute to anti-tumour activity of 4-1BB agonists in humans and suggest that combining 4-1BB-stimulation with IL-12 could be beneficial for ex vivo or in vivo expansion and activation of NK cells for cancer immunotherapy.

Natural killer (NK) cells in antibacterial innate immunity: angels or devils?

Natural killer (NK) cells were first described as immune leukocytes that could kill tumor cells and soon after were reported to kill virus-infected cells. In the mid-1980s, 10 years after their discovery, NK cells were also demonstrated to contribute to the fight against bacterial infection, particularly because of crosstalk with other leukocytes. A wide variety of immune cells are now recognized to interact with NK cells through the production of cytokines such as interleukin (IL)-2, IL-12, IL-15 and IL-18, which boost NK cell activities. The recent demonstration that NK cells express pattern recognition receptors, namely Toll-like and nucleotide oligomerization domain (NOD)-like receptors, led to the understanding that these cells are not only under the control of accessory cells, but can be directly involved in the antibacterial response thanks to their capacity to recognize pathogen-associated molecular patterns. Interferon (IFN)-γ is the predominant cytokine produced by activated NK cells. IFN-γ is a key contributor to antibacterial immune defense. However, in synergy with other inflammatory cytokines, IFN-γ can also lead to deleterious effects similar to those observed during sepsis. Accordingly, as the main source of IFN-γ in the early phase of infection, NK cells display both beneficial and deleterious effects, depending on the circumstances.

Expression pattern of cathepsin W isoforms in peripheral blood and gastroesophageal mucosa of patients with gastroesophageal reflux disease

Cathepsin W is exclusively expressed in immune cells, and a novel isoform was identified previously. To characterize the expression pattern of the wildtype and isoform Ins10, specific polymerase chain reaction assays were generated and used to study respective transcript levels in peripheral blood cells and gastric biopsies in healthy subjects. The wildtype-encoding transcript levels were 3- and 9-fold higher in mucosal samples and peripheral immune cells, respectively (p<0.05). The predominant expression of wildtype form by infiltrating immune cells was confirmed in 116 patients with gastroesophageal reflux disease and 27 reflux-negative individuals demonstrating that cathepsin W expression is not altered in this disease.

State of the art in natural killer cell malignancies

The recently updated World Health Organization (WHO) classification of tumors of hematopoietic and lymphoid tissues, published in 2008, has made great advances in revising the disorders previously included in the pool of natural killer (NK) cell tumors. Although NK cell neoplasms represent a relatively rare group of diseases, accounting for <5% of all lymphoid neoplasms, they include very distinctive conditions both clinically and pathologically. This family of diseases includes the most indolent clinical forms, such as the provisional new entry of chronic lymphoproliferative disorder of NK cells (CLPD-NK) in the WHO classification, as well as one of the most fatal diseases recognized in medical oncology, aggressive NK cell leukemia (ANKL), which is characterized by a prognosis of weeks, or even days. In addition, some disorders previously identified as blastic NK cell lymphoma within the NK cell system have been more properly defined and included in the blastic plasmacytoid dentritic cell neoplasms, although rare cases of bona fide immature NK lymphoid tumors (now classified as NK cell lymphoblastic leukemia/lymphoma) have been reported in the literature. This paper focuses on recent concepts and progress in morphology, pathogenesis, clinicopathological features, treatment approaches, and outcomes of NK cell malignancies.

Natural killer cell neoplasm: biology and pathology

Natural killer (NK) cell neoplasm is a heterogeneous disease group. In the latest World Health Organization (WHO) classification of tumours of hematopoietic and lymphoid tissues (2008), disease entities considered as NK-cell derivation include NK-lymphoblastic leukemia/lymphoma, chronic lymphoproliferative disorders of NK cells, aggressive NK-cell leukemia, and extranodal NK-cell lymphoma, nasal-type. Despite recent advances in NK-cell research, which have expanded our understanding of the biology of NK-cell neoplasm, it cannot yet be sharply delineated from myeloid neoplasms and T-cell neoplasms even in some "well-known" entity, such as extranodal NK/T-cell lymphoma. This review describes current knowledge of the biology of NK cells and pathology of NK neoplasms as classified in the 2008 WHO classification of tumours of hematopoietic and lymphoid tissues.