Homeostatic proliferation generates long-lived natural killer cells that respond against viral infection

Cells of the immune system undergo homeostatic proliferation during times of lymphopenia induced by certain viral infections or caused by chemotherapy and radiation treatment. Natural killer (NK) cells are no exception and can rapidly expand in number when placed into an environment devoid of these cells. We explored the lifespan and function of mouse NK cells that have undergone homeostatic proliferation in various settings of immunodeficiency. Adoptive transfer of mature NK cells into lymphopenic mice resulted in the generation of a long-lived population of NK cells. These homeostasis-driven NK cells reside in both lymphoid and nonlymphoid organs for >6 mo and, similar to memory T cells, self-renew and slowly turn over at steady state. Furthermore, homeostatically expanded NK cells retained their functionality many months after initial transfer and responded robustly to viral infection. These findings highlight the ability of mature NK cells to self-renew and possibly persist in the host for months or years and might be of clinical importance during NK cell adoptive immunotherapy for the treatment of certain cancers.

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Activation Status Dictates the Function of Unlicensed Natural Killer Cells

Blood Advances ◽

10.1182/bloodadvances.2021004589 ◽

2021 ◽

Author(s):

Ethan G Aguilar ◽

Cordelia Dunai ◽

Sean J. Judge ◽

Anthony Elston Zamora ◽

Lam T. Khuat ◽

...

Keyword(s):

Viral Infection ◽

Nk Cells ◽

Natural Killer ◽

Viral Infections ◽

Nk Cell ◽

T Cell Response ◽

High Dose ◽

Hematopoietic Stem ◽

Innate Defense ◽

Activation Status

Natural Killer (NK) cells are involved in innate defense against viral infection and cancer. NK cells can be divided into subsets based on the ability of different receptors to bind to major histocompatibility (MHC) class I molecules resulting in differential responses upon activation in a process called "licensing" or "arming". NK cells expressing receptors that bind self-MHC are considered licensed due to augmented effector lytic function capability compared to unlicensed subsets. However, we demonstrated unlicensed NK subsets instead positively regulate the adaptive T cell response during viral infections due to localization and cytokine production. We demonstrate here that the differential effects of the two types of NK subsets is contingent on the environment using viral infection and hematopoietic stem cell transplantation (HSCT) models. Infection of mice with high-dose (HD) MCMV leads to a loss of licensing-associated differences as compared to mice with low-dose infection, as the unlicensed NK subset no longer localized in lymph nodes (LN), but instead remained at the site of infection. Similarly, the patterns observed during HD infection paralleled with the phenotypes of both human and mouse NK cells in a HSCT setting where NK cells exhibit an activated phenotype. However, in contrast to effects of subset depletion in T-replete models, the licensed NK cell subsets still dominated anti-viral responses post-HSCT. Overall, our results highlight the intricate tuning of the NK cells and how it impacts overall immune responses with regard to licensing patterns, as it is dependent on the level of stimulation and their activation status.

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Viral Infection of Human Natural Killer Cells

Viruses ◽

10.3390/v11030243 ◽

2019 ◽

Vol 11 (3) ◽

pp. 243 ◽

Cited By ~ 9

Author(s):

Elisabeth van Erp ◽

Mirjam van Kampen ◽

Puck van Kasteren ◽

Jelle de Wit

Keyword(s):

Viral Infection ◽

Nk Cells ◽

Natural Killer ◽

Viral Entry ◽

Viral Infections ◽

Nk Cell ◽

Cell Infection ◽

Comprehensive Overview ◽

Human Natural Killer Cells ◽

Syncytial Virus

Natural killer (NK) cells are essential in the early immune response against viral infections, in particular through clearance of virus-infected cells. In return, viruses have evolved multiple mechanisms to evade NK cell-mediated viral clearance. Several unrelated viruses, including influenza virus, respiratory syncytial virus, and human immunodeficiency virus, can directly interfere with NK cell functioning through infection of these cells. Viral infection can lead to immune suppression, either by downregulation of the cytotoxic function or by triggering apoptosis, leading to depletion of NK cells. In contrast, some viruses induce proliferation or changes in the morphology of NK cells. In this review article, we provide a comprehensive overview of the viruses that have been reported to infect NK cells, we discuss their mechanisms of entry, and describe the interference with NK cell effector function and phenotype. Finally, we discuss the contribution of virus-infected NK cells to viral load. The development of specific therapeutics, such as viral entry inhibitors, could benefit from an enhanced understanding of viral infection of NK cells, opening up possibilities for the prevention of NK cell infection.

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T-BET and EOMES Accelerate and Enhance Functional Differentiation of Human Natural Killer Cells

Frontiers in Immunology ◽

10.3389/fimmu.2021.732511 ◽

2021 ◽

Vol 12 ◽

Author(s):

Laura Kiekens ◽

Wouter Van Loocke ◽

Sylvie Taveirne ◽

Sigrid Wahlen ◽

Eva Persyn ◽

...

Keyword(s):

Nk Cells ◽

Natural Killer ◽

Cell Biology ◽

Nk Cell ◽

Current Knowledge ◽

Functional Differentiation ◽

Cell Maturation ◽

Hematopoietic Stem ◽

And Function

T-bet and Eomes are transcription factors that are known to be important in maturation and function of murine natural killer (NK) cells. Reduced T-BET and EOMES expression results in dysfunctional NK cells and failure to control tumor growth. In contrast to mice, the current knowledge on the role of T-BET and EOMES in human NK cells is rudimentary. Here, we ectopically expressed either T-BET or EOMES in human hematopoietic progenitor cells. Combined transcriptome, chromatin accessibility and protein expression analyses revealed that T-BET or EOMES epigenetically represses hematopoietic stem cell quiescence and non-NK lineage differentiation genes, while activating an NK cell-specific transcriptome and thereby drastically accelerating NK cell differentiation. In this model, the effects of T-BET and EOMES are largely overlapping, yet EOMES shows a superior role in early NK cell maturation and induces faster NK receptor and enhanced CD16 expression. T-BET particularly controls transcription of terminal maturation markers and epigenetically controls strong induction of KIR expression. Finally, NK cells generated upon T-BET or EOMES overexpression display improved functionality, including increased IFN-γ production and killing, and especially EOMES overexpression NK cells have enhanced antibody-dependent cellular cytotoxicity. Our findings reveal novel insights on the regulatory role of T-BET and EOMES in human NK cell maturation and function, which is essential to further understand human NK cell biology and to optimize adoptive NK cell therapies.

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Generation of human natural killer cells from immature progenitors does not require marrow stromal cells

Blood ◽

10.1182/blood.v84.3.841.841 ◽

1994 ◽

Vol 84 (3) ◽

pp. 841-846 ◽

Cited By ~ 37

Author(s):

MR Silva ◽

R Hoffman ◽

EF Srour ◽

JL Ascensao

Keyword(s):

Nk Cells ◽

Natural Killer ◽

Mononuclear Cells ◽

Viral Infections ◽

Nk Cell ◽

Interleukin 2 ◽

Peripheral Blood Mononuclear ◽

Specific Lysis ◽

Human Natural Killer Cells

Abstract Human natural killer (NK) cells comprise 10% to 15% of peripheral blood mononuclear cells and have an important role in immune responses against tumors, viral infections, and graft rejection. NK cells originate in bone marrow (BM), but their progenitors and lineage development have not been completely characterized. We studied the generation of NK cells from purified CD34+HLADR- and CD34+HLADR+ BM progenitors and the influence of various cytokines on their production. We show that CD3-CD56+ cytotoxic NK cells can develop from both progenitors populations when interleukin-2 (IL-2) is present in an in vitro suspension culture system containing IL-1 alpha and stem cell factor. Up to 83.8% and 98.6% CD3-CD56+ cells were detected in CD34+HLADR- and CD34+DR+ cultures, respectively, after 5 weeks of culture; significant numbers of NK cells were first detected after 2 weeks. Cytotoxic activity paralleled NK cell numbers; up to 70% specific lysis at an effector:target ratio of 10:1 was observed at 5 weeks. IL-7 also triggered development of CD3-CD56+ cells from these immature progenitors (up to 24% and 55% appeared in CD34+HLADR- and CD34+HLADR+ cultures, respectively). Our data suggest that BM stromas are not necessary for NK cell development and that IL-2 remains essential for this lineage development and differentiation.

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Dysregulation of Natural Killer Cells in Obesity

Cancers ◽

10.3390/cancers11040573 ◽

2019 ◽

Vol 11 (4) ◽

pp. 573 ◽

Cited By ~ 15

Author(s):

Donal O’Shea ◽

Andrew E. Hogan

Keyword(s):

Nk Cells ◽

Natural Killer ◽

Cell Biology ◽

Viral Infections ◽

Nk Cell ◽

Viral Immunity ◽

Host Protection ◽

Cell Functions ◽

Innate Lymphocytes ◽

The Impact

Natural killer (NK) cells are a population of lymphocytes which classically form part of the innate immune system. They are defined as innate lymphocytes, due to their ability to kill infected or transformed cells without prior activation. In addition to their cytotoxic abilities, NK cells are also rapid producers of inflammatory cytokines such as interferon gamma (IFN-γ) and are therefore a critical component of early immune responses. Due to these unique abilities, NK cells are a very important component of host protection, especially anti-tumour and anti-viral immunity. Obesity is a worldwide epidemic, with over 600 million adults and 124 million children now classified as obese. It is well established that individuals who are obese are at a higher risk of many acute and chronic conditions, including cancer and viral infections. Over the past 10 years, many studies have investigated the impact of obesity on NK cell biology, detailing systemic dysregulation of NK cell functions. More recently, several studies have investigated the role of NK cells in the homeostasis of adipose tissue and the pathophysiology of obesity. In this review, we will discuss in detail these studies and focus on emerging data detailing the metabolic mechanisms altering NK cells in obesity.

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Evidence for Killing of Mesenchymal Stem Cells (MSC) by Autologous Natural Killer Lymphocytes.

Blood ◽

10.1182/blood.v104.11.1290.1290 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1290-1290 ◽

Cited By ~ 1

Author(s):

Alessandro Poggi ◽

Anna-Maria Massaro ◽

Simone Negrini ◽

Ivana Pierri ◽

Manuela Balocco ◽

...

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

T Lymphocytes ◽

Nk Cells ◽

Natural Killer ◽

Viral Infections ◽

Nk Cell ◽

Cell Lineage ◽

Culture Conditions ◽

Inhibitory Receptors

Abstract In this study, Mesenchymal Stem Cells (MSC) were obtained from bone marrow of 10 patients suffering from acute myeloid leukemia (AML), six M0/1 two M2, and two M5 (according to the FAB classification), 8 out of 10 in post-chemotherapy complete remission. These cells differentiated into adipocytes or osteoblasts under appropriate culture conditions. MSC were CD44+, CD73a+ CD73b+ CD105+, beta1 integrin+, ICAM1+, HLA-I+, HLA-II+ (variable proportions), CD45−, CD31−, CD34− and they constitutively expressed the stress-inducible MHC-related molecules MIC-A and the UL16 (induced at the surface of cells infected by cytomegalovirus) binding protein ULBP3. These molecules are reported ligands for the NKG2D receptor expressed by natural killer (NK) and CD8+ T lymphocytes, effector cells that are thought to play a role in host defence against tumors. NK cells have also been shown to regulate normal differentiation of hemopoietic precursor into the myeloid or lymphoid cell lineage. Moreover, it has been stated that NK cells are not able to damage autologous cells, as they receive negative signals through inhibitory receptors, including killer Ig-like receptors (KIR) or C-type lectin inhibitory receptors (CLIR), which bind to HLA-I discrete alleles. Surprisingly, we found that autologous IL2-activated, but not freshly isolated, NK cells lysed MSC, while T lymphocytes did not kill self or non-self MSC. Binding of ICAM-1 expressed by MSC to its receptor, the integrin LFA-1, expressed by NK cells plays a key role in MSC/NK interaction. More importantly, NKG2D/MICA and/or NKG2D/ULBP3 engagement is responsible for the delivery of lethal hit. Conversely, it appears that HLA-I molecules do not protect MSC from NK cell-mediated injury. Taken together, these data suggest that NK cells, when activated as it may occur during the first response to viral infections, are able to eliminate MSC, thus altering the normal interactions with hemopoietic precursors and possibly affecting their differentiation. This mechanism might also contribute to the development of aberrant precursors as observed in acute leukaemias.

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Characterization of the defective interaction between a subset of natural killer cells and dendritic cells in HIV-1 infection

Journal of Experimental Medicine ◽

10.1084/jem.20060894 ◽

2006 ◽

Vol 203 (10) ◽

pp. 2339-2350 ◽

Cited By ~ 129

Author(s):

Domenico Mavilio ◽

Gabriella Lombardo ◽

Audrey Kinter ◽

Manuela Fogli ◽

Andrea La Sala ◽

...

Keyword(s):

Dendritic Cells ◽

Nk Cells ◽

Natural Killer ◽

Nk Cell ◽

Cell Subset ◽

Interferon Γ ◽

And Function ◽

Hiv 1

In this study, we demonstrate that the in vitro interactions between a CD56neg/CD16pos (CD56neg) subset of natural killer (NK) cells and autologous dendritic cells (DCs) from HIV-1–infected viremic but not aviremic individuals are markedly impaired and likely interfere with the development of an effective immune response. Among the defective interactions are abnormalities in the process of reciprocal NK–DC activation and maturation as well as a defect in the NK cell–mediated editing or elimination of immature DCs (iDCs). Notably, the lysis of mature DCs (mDCs) by autologous NK cells was highly impaired even after the complete masking of major histocompatibility complex I molecules, suggesting that the defective elimination of autologous iDCs is at the level of activating NK cell receptors. In this regard, the markedly impaired expression/secretion and function of NKp30 and TNF-related apoptosis-inducing ligand, particularly among the CD56neg NK cell subset, largely accounts for the highly defective NK cell–mediated lysis of autologous iDCs. Moreover, mDCs generated from HIV-1 viremic but not aviremic patients are substantially impaired in their ability to secrete interleukin (IL)-10 and -12 and to prime the proliferation of neighboring autologous NK cells, which, in turn, fail to secrete adequate amounts of interferon-γ.

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Sars-Cov-2 Spike 1 protein control Natural killer cells activation via HLA-E/NKG2A pathway.

10.21203/rs.3.rs-31860/v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Daria Bortolotti ◽

Valentina Gentili ◽

Sabrina Rizzo ◽

Antonella Rotola ◽

Roberta Rizzo

Keyword(s):

Epithelial Cells ◽

Nk Cells ◽

Natural Killer ◽

Cell Activation ◽

Viral Infections ◽

Nk Cell ◽

Lung Epithelial Cells ◽

Lung Epithelial ◽

Spike Proteins

Abstract Natural killer (NK) cells are important in the control of viral infections. However, the role of NK cells during Sars-Cov-2 infection has previously not been identified. Peripheral blood NK cells from Sars-Cov and Sars-Cov-2 naïve subjects were evaluated for their activation, degranulation, interferon-gamma expression in the presence of Sars-Cov and Sars-Cov-2 spike proteins. K562 and lung epithelial cells were transfected with spike proteins and co-cultured with NK cells. The analysis was performed by flow cytometry and immune-fluorescence. Sars-Cov and Sars-Cov-2 spike proteins did not alter NK cell activation in K562 in vitro model. On the contrary, Sars-Cov-2 spike 1 protein (SP1) intracellular expression by lung epithelial cells resulted in NK cell reduced degranulation. Further experiments revealed a concomitant induction of HLA-E expression on the surface of lung epithelial cells and the recognition of a SP1-derived HLA-E-binding peptide. Simultaneously, there was the up-modulation of the inhibitory receptor NKG2A/CD94 on NK cells when SP1 is expressed in lung epithelial cells. We ruled out GATA3 transcription factor as responsible for HLA-E increased levels and HLA-E/NKG2A interaction as implicate in NK cells exhaustion. We show for the first time that NK cells are affected by SP1 expression in lung epithelial cells via HLA-E/NKG2A interaction. The resulting NK cells exhaustion might contribute to immunopathogenesis in Sars-Cov-2 infection.

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Allotype-specific processing of the CD16a N45-glycan from primary human natural killer cells and monocytes

Glycobiology ◽

10.1093/glycob/cwaa002 ◽

2020 ◽

Vol 30 (7) ◽

pp. 427-432

Author(s):

Kashyap R Patel ◽

Jacob T Roberts ◽

Adam W Barb

Keyword(s):

Natural Killer Cells ◽

Nk Cells ◽

Natural Killer ◽

Viral Infections ◽

Nk Cell ◽

Cell Surface Receptor ◽

Mass Spectrometry Analysis ◽

Healthy Human ◽

Killer Cells ◽

Spectrometry Analysis

Abstract Fc γ receptor IIIa/CD16a is an activating cell surface receptor with a well-defined role in natural killer (NK) cell and monocyte effector function. The extracellular domain is decorated with five asparagine (N)-linked glycans; N-glycans at N162 and N45 directly contribute to high-affinity antibody binding and protein stability. N-glycan structures at N162 showed significant donor-dependent variation in a recent study of CD16a isolated from primary human NK cells, but structures at N45 were relatively homogeneous. In this study, we identified variations in N45 glycan structures associated with a polymorphism coding for histidine instead of leucine at position 48 of CD16a from two heterozygous donors. It is known that H48 homozygous individuals suffer from immunodeficiency and recurrent viral infections. A mass spectrometry analysis of protein isolated from the primary natural killer cells of individuals expressing both CD16a L48 and H48 variants demonstrated clear processing differences at N45. CD16a H48 displayed a greater proportion of complex-type N45 glycans compared to the more common L48 allotype with predominantly hybrid N45-glycoforms. Structures at the four other N-glycosylation sites showed minimal differences from data collected on donors expressing only the predominant L48 variant. CD16a H48 purified from a pool of monocytes similarly displayed increased processing at N45. Here, we provide evidence that CD16a processing is affected by the H48 residue in primary NK cells and monocytes from healthy human donors.

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Natural Killer Cell–mediated Lysis of Autologous Cells Modified by Gene Therapy

Journal of Experimental Medicine ◽

10.1084/jem.189.12.1855 ◽

1999 ◽

Vol 189 (12) ◽

pp. 1855-1862 ◽

Cited By ~ 25

Author(s):

Concetta Liberatore ◽

Marusca Capanni ◽

Nicola Albi ◽

Isabella Volpi ◽

Elena Urbani ◽

...

Keyword(s):

Gene Therapy ◽

Nk Cells ◽

Natural Killer ◽

Viral Infections ◽

Nk Cell ◽

Killer Cell ◽

Marker Gene ◽

Gene Mutations ◽

Hla B27 ◽

Leukocyte Antigen

This study investigated the role of natural killer (NK) cells as effectors of an immune response against autologous cells modified by gene therapy. T lymphocytes were transduced with LXSN, a retroviral vector adopted for human gene therapy that carries the selectable marker gene neo, and the autologous NK response was evaluated. We found that (i) infection with LXSN makes cells susceptible to autologous NK cell–mediated lysis; (ii) expression of the neo gene is responsible for conferring susceptibility to lysis; (iii) lysis of neo-expressing cells is clonally distributed and mediated only by NK clones that exhibit human histocompatibility leukocyte antigen (HLA)-Bw4 specificity and bear KIR3DL1, a Bw4-specific NK inhibitory receptor; and (iv) the targets are cells from HLA-Bw4+ individuals. Finally, neo peptides anchoring to the Bw4 allele HLA-B27 interfered with KIR3DL1-mediated recognition of HLA-B27, i.e., they triggered NK lysis. Moreover, neo gene mutations preventing translation of two of the four potentially nonprotective peptides reduced KIR3DL1+ NK clone–mediated autologous lysis. Thus, individuals expressing Bw4 alleles possess an NK repertoire with the potential to eliminate autologous cells modified by gene therapy. By demonstrating that NK cells can selectively detect the expression of heterologous genes, these observations provide a general model of the NK cell–mediated control of viral infections.

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