Adrenal tumors provide insight into the role of cortisol in NK cell activity

2021 ◽  
Author(s):  
Andrew E. Greenstein ◽  
Mouhammed Amir Habra ◽  
Subhagya A. Wadekar ◽  
Andreas Grauer
Keyword(s):  
Immune Response ◽  
Nk Cells ◽  
Cell Activation ◽  
Nk Cell ◽  
Phase 1 ◽  
Cell Activity ◽  
The Cancer Genome Atlas ◽  
Adrenal Tumors ◽  
Steroid Synthesis

Elevated glucocorticoid (GC) activity may limit tumor immune response and immune checkpoint inhibitor (ICI) efficacy. Adrenocortical carcinoma (ACC) provides a unique test case to assess correlates of GC activity, as approximately half of ACC patients exhibit excess GC production (GC+). ACC multi-omics were analyzed to identify molecular consequences of GC+ and assess the rationale for combining the glucocorticoid receptor (GR) antagonist relacorilant with an ICI. GC status, mRNA expression, and DNA mutation and methylation data from 71 adrenal tumors were accessed via The Cancer Genome Atlas. Expression of 858 genes differed significantly between GC- and GC+ ACC cases. KEGG pathway analysis showed higher gene expression of 3 pathways involved in steroid synthesis and secretion in GC+ cases. Fifteen pathways, most related to NK cells and other immune activity, showed lower expression. Hypomethylation was primarily observed in the steroid synthesis pathways. Tumor-infiltrating CD4+ memory (P=.003), CD8+ memory (P=.001), and NKT-cells (P=.014) were depleted in GC+ cases; tumor-associated neutrophils were enriched (P=.001). Given the pronounced differences between GC+ and GC- ACC, the effects of cortisol on NK cells were assessed in vitro (NK cells from human PBMCs stimulated with IL-2 or IL-12/15). Cortisol suppressed, and relacorilant restored, NK cell activation, proliferation, and direct tumor cell killing. Thus, GR antagonism may increase the abundance and function of NK and other immune cells in the tumor microenvironment, promoting immune response in GC+ ACC and other malignancies with GC+. This hypothesis will be tested in a phase 1 trial of relacorilant + ICI.

scholarly journals T cell regulation of natural killer cells

2013 ◽  
Vol 210 (6) ◽  
pp. 1065-1068 ◽  
Author(s):  
Yann Kerdiles ◽  
Sophie Ugolini ◽  
Eric Vivier
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Nk Cells ◽  
Natural Killer ◽  
Cell Activation ◽  
Nk Cell ◽  
Cell Activity ◽  
Adaptive Immune System ◽  
Nk Cell Activity ◽  
Promising Target

In light of their role in the immune response against tumors and viruses, natural killer (NK) cells represent a promising target for immunotherapy. Before this target is reached, the various mechanisms that control NK cell activity must first be identified and understood. In the past decades, studies have identified two critical processes that prevent spontaneous NK cell–mediated autoimmune activation while maximizing the efficiency of these cells during an immune response. First is the education process, whereby NK cells adapt to their environment by sensing ligands for inhibitory and activating receptors. Second is the priming phase of NK cell activation, which arms NK cells with appropriate cytotoxic molecules during inflammation. New studies now indicate that NK cell proliferation, accumulation, and activation are also under the control of regulatory T cells that restrict availability of IL-2 released by activated CD4+ T cells. Together with other recent studies, these data highlight the importance of the adaptive immune system in the regulation of NK cell activity.

In-Vitro Culture of Human CD80/IL2 Lentivirus Transduced Acute Myeloid Leukemia Cells (AML) Promote NK Cell Activation and Cytolytic Activity

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2969-2969
Author(s):  
Wendy Ingram ◽  
Lucas Chan ◽  
Hayrettin Guven ◽  
Shahram Kordasti ◽  
Linda Barber ◽  
...  
Keyword(s):  
Cell Culture ◽  
T Cells ◽  
Nk Cells ◽  
Cell Activation ◽  
Nk Cell ◽  
Cell Activity ◽  
Cell Cytotoxicity ◽  
Release Assay ◽  
Nk Cell Cytotoxicity

Abstract Natural killer (NK) cells are increasingly recognized as an important component in the graft versus leukemia response following allogeneic hematopoietic stem cell transplantation. Immunotherapeutic strategies aim to promote NK cell activity however, the presence of regulatory T cells (Tregs) which inhibit effector immune responses pose a potential challenge to the efficacy of such regimens. We have previously shown that ‘in-vitro’ culture of AML cells transduced with a self-inactivating lentivirus (LV) encoding CD80 (B7.1) and IL2 enhance allogeneic (allo) and autologous (auto) T cell proliferation and cytotoxicity. The effect on NK cell activity and Tregs has not previously been studied and is of particular importance as IL2 stimulates NK cell and Treg activity. Peripheral blood mononuclear cells (PBMCs) from healthy donors (allo) or AML patients (auto) were cultured for 7 days ‘in-vitro’ with either unmodified or LV-CD80/IL2 AMLs. The number of NK cells (CD3−CD56+) and Tregs (CD3+CD4+CD25highFoxp3+) was examined by multi-color flow cytometry. We observe an increase in the number of NK cells (p<0.001) with an increase in the expression of the activation receptors NKp30, NKp44, CD244, CD25, CD69 and HLA-DR following allo culture with LV-CD80/IL2 AML compared with unmodified AML. Autologous culture provides a weaker stimulus ‘in-vitro’ however, a higher number of NK cells (p=0.002) and a consistent increased expression of the activation receptors NKp30, NKp44, NKp46, NKG2D, NKG2C and CD69, as well as up regulation of the cytolytic marker CD107a was detected following auto stimulation with LV-CD80/IL2 AML compared with unmodified AML. Up regulation of CD107a was also observed in allo cultures stimulated with both unmodified and LV-CD80/IL2 AML cells. In contrast, a consistent increase in the number of Tregs was observed following allo (p=0.043) but not auto (p=0.515) LV-CD80/IL2 AML culture. Foxp3 may be unregulated on activated CD4+ T cells therefore the number of CD3+CD4+CD25highFoxp3+CD27+ Tregs was also examined. An increase in the number of CD27+ Tregs was observed following allo (p=0.017) but not auto (p=0.807) LV-CD80/IL2 AML cell culture. A standard 51Cr release assay was used to examine cytotoxicity against primary unmodified AMLs on days 0 and 7 following LV-CD80/IL2 AML cell culture. Tregs are capable of suppressing CD4+ and CD8+ T cell and NK cell cytotoxicity, therefore lysis of unmodified AMLs was initially examined using whole PBMCs as effectors. Even in the presence of Tregs an increase in lysis of allo unmodified AMLs was observed: 2.2% day 0, 4.6% following culture with unmodified AMLs; 20.4% following LV-CD80/IL2 AML cell culture. Importantly, an increase in lysis of auto AML was also detected: 0% day 0, 2.1% unmodified AML culture, 16% LV-CD80/IL2 AML culture. The ratio of Tregs to effector T cells is important for the suppressive function of Tregs. The number of Tregs in the cytotoxicity assays is likely to be lower than that required for a significant suppressive effect to be observed. We next examined the cytotoxicity of NK cells using K562 and unmodified AMLs as targets. NK cells were negatively isolated on days 0 and 7 following either unmodified AML or LV-CD80/IL2 AML cell culture and used as effectors in a 51Cr release assay. In keeping with the changes in NK cell activation receptor expression, we demonstrate a significant increase in NK cell cytotoxicity against both K562 and primary unmodified AMLs. Lysis of K562 increased from 46.7% on day 0 to 90.4% after LV-CD80/IL2 stimulation. Importantly, an increase in lysis of both allo and auto unmodified AMLs was detected following LV-CD80/IL2 AML cell culture. Lysis of allo AMLs increased from a median of 11.8% on day 0, 8.7% following culture with unmodified AML to 20.1% following LV-CD80/IL2 AML cell culture using a low effector: target ratio of just 5:1. Importantly, an increase in lysis of auto AML from 0.4% on day 0, 2.1% with unmodified AML cells to 21.5% following LV-CD80/IL2 AML stimulation was observed. LV-CD80/IL2 AML cells enhance NK cell activation and cytotoxicity against allo and auto unmodified AMLs. Furthermore, cytotoxicity is enhanced even in the presence of Tregs with an increase in Tregs only observed following allo culture. Vaccination of patients with LV-CD80/IL2 AML cells therefore represents a potential strategy to promote T and NK cell cytotoxicity and enhance anti-leukemia immune responses in patients with AML.

scholarly journals miR-1224 contributes to ischemic stroke-mediated natural killer cell dysfunction by targeting Sp1 signaling

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Yan Feng ◽  
Yan Li ◽  
Ying Zhang ◽  
Bo-Hao Zhang ◽  
Hui Zhao ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Nk Cells ◽  
Natural Killer ◽  
Brain Ischemia ◽  
Cell Activation ◽  
Nk Cell ◽  
Cell Activity ◽  
Passive Transfer ◽  
Immune Defense ◽  
Nk Cell Activity

Abstract Background Brain ischemia compromises natural killer (NK) cell-mediated immune defenses by acting on neurogenic and intracellular pathways. Less is known about the posttranscriptional mechanisms that regulate NK cell activation and cytotoxicity after ischemic stroke. Methods Using a NanoString nCounter® miRNA array panel, we explored the microRNA (miRNA) profile of splenic NK cells in mice subjected to middle cerebral artery occlusion. Differential gene expression and function/pathway analysis were applied to investigate the main functions of predicted miRNA target genes. miR-1224 inhibitor/mimics transfection and passive transfer of NK cells were performed to confirm the impact of miR-1224 in NK cells after brain ischemia. Results We observed striking dysregulation of several miRNAs in response to ischemia. Among those miRNAs, miR-1224 markedly increased 3 days after ischemic stroke. Transfection of miR-1224 mimics into NK cells resulted in suppression of NK cell activity, while an miR-1224 inhibitor enhanced NK cell activity and cytotoxicity, especially in the periphery. Passive transfer of NK cells treated with an miR-1224 inhibitor prevented the accumulation of a bacterial burden in the lungs after ischemic stroke, suggesting an enhanced immune defense of NK cells. The transcription factor Sp1, which controls cytokine/chemokine release by NK cells at the transcriptional level, is a predicted target of miR-1224. The inhibitory effect of miR-1224 on NK cell activity was blocked in Sp1 knockout mice. Conclusions These findings indicate that miR-1224 may serve as a negative regulator of NK cell activation in an Sp1-dependent manner; this mechanism may be a novel target to prevent poststroke infection specifically in the periphery and preserve immune defense in the brain.

scholarly journals NT5E/CD73 as Correlative Factor of Patient Survival and Natural Killer Cell Infiltration in Glioblastoma

2019 ◽  
Vol 8 (10) ◽  
pp. 1526 ◽  
Author(s):  
Jiao Wang ◽  
Sandro Matosevic
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Cell Activation ◽  
Patient Survival ◽  
Nk Cell ◽  
Killer Cell ◽  
Surface Protein ◽  
The Cancer Genome Atlas ◽  
Negative Prognostic Factor ◽  
A Cell

CD73, a cell-surface protein encoded by the gene NT5E, is overexpressed in glioblastoma (GBM), where it contributes to the tumor’s pathophysiology via the generation of immunosuppressive adenosine. Adenosinergic signaling, in turn, drives immunosuppression of natural killer (NK) cells through metabolic and functional reprogramming. The correlation of CD73 with patient survival in relation to GBM pathology and the intratumoral infiltration of NK cells has not been comprehensively studied before. Here, we present an analysis of the prognostic relevance of CD73 in GBM based on transcriptional gene expression from patient data from The Cancer Genome Atlas (TCGA) database. Utilizing bioinformatics data mining tools, we explore the relationship between GBM prognosis, NT5E expression, and intratumoral presence of NK cells. Our analysis demonstrates that CD73 is a negative prognostic factor for GBM and that presence of NK cells may associate with improved prognosis. Moreover, the interplay between expression of NT5E and specific NK genes hints to potential functional effects of CD73 on NK cell activation.

scholarly journals SARS-CoV-2 Spike 1 Protein Controls Natural Killer Cell Activation via the HLA-E/NKG2A Pathway

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1975 ◽  
Author(s):  
Daria Bortolotti ◽  
Valentina Gentili ◽  
Sabrina Rizzo ◽  
Antonella Rotola ◽  
Roberta Rizzo
Keyword(s):  
Epithelial Cells ◽  
Nk Cells ◽  
Natural Killer ◽  
Cell Activation ◽  
Nk Cell ◽  
Killer Cell ◽  
Lung Epithelial Cells ◽  
Lung Epithelial ◽  
Spike Proteins

Natural killer cells are important in the control of viral infections. However, the role of NK cells during severe acute respiratory syndrome coronavirus 2 (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, and 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 a 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 an SP1-derived HLA-E-binding peptide. Simultaneously, there was increased modulation of the inhibitory receptor NKG2A/CD94 on NK cells when SP1 was expressed in lung epithelial cells. We ruled out the GATA3 transcription factor as being responsible for HLA-E increased levels and HLA-E/NKG2A interaction as implicated in NK cell 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.

Elevated CD54 Expression Renders CD4+ T Cells Susceptible to Natural Killer Cell-Mediated Killing

2019 ◽  
Vol 220 (12) ◽  
pp. 1892-1903 ◽  
Author(s):  
Xi Chen ◽  
Huihui Chen ◽  
Zining Zhang ◽  
Yajing Fu ◽  
Xiaoxu Han ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Nk Cells ◽  
Natural Killer ◽  
Cd4 T Cells ◽  
Nk Cell ◽  
Killer Cell ◽  
Adaptive Immune Response ◽  
Phenotypic Analysis

Abstract Background Natural killer (NK) cells are an important type of effector cell in the innate immune response, and also have a role in regulation of the adaptive immune response. Several studies have indicated that NK cells may influence CD4+ T cells during HIV infection. Methods In total, 51 HIV-infected individuals and 15 healthy controls participated in this study. We performed the flow cytometry assays and real-time PCR for the phenotypic analysis and the functional assays of NK cell-mediated deletion of CD4+ T cells, phosphorylation of nuclear factor-κB (NF-κB/p65) and the intervention of metformin. Results Here we detected high CD54 expression on CD4+ T cells in HIV-infected individuals, and demonstrate that upregulated CD54 is associated with disease progression in individuals infected with HIV. We also show that CD54 expression leads to the deletion of CD4+ T cells by NK cells in vitro, and that this is modulated by NF-κB/p65 signaling. Further, we demonstrate that metformin can suppress CD54 expression on CD4+ T cells by inhibiting NF-κB/p65 phosphorylation. Conclusions Our data suggest that further studies to evaluate the potential role of metformin as adjunctive therapy to reconstitute immune function in HIV-infected individuals are warranted.

scholarly journals Impairment of Intramacrophagic Brucella suis Multiplication by Human Natural Killer Cells through a Contact-Dependent Mechanism

2004 ◽  
Vol 72 (4) ◽  
pp. 2303-2311 ◽  
Author(s):  
Jacques Dornand ◽  
Virginie Lafont ◽  
Jane Oliaro ◽  
Annie Terraza ◽  
Elsa Castaneda-Roldan ◽  
...  
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Interleukin 2 ◽  
Cell Activity ◽  
Human Brucellosis ◽  
Cell Contact ◽  
Necrosis Factor Alpha ◽  
Brucella Suis ◽  
Human Natural Killer Cells

ABSTRACT Brucella spp. are facultative intracellular bacteria that can establish themselves and cause chronic disease in humans and animals. NK cells play a key role in host defense. They are implicated in an early immune response to a variety of pathogens. However, it was shown that they do not control Brucella infection in mice. On the other hand, NK cell activity is impaired in patients with acute brucellosis, and recently it was demonstrated that human NK cells mediate the killing of intramacrophagic Mycobacterium tuberculosis in in vitro infection. Therefore, we have analyzed the behavior of Brucella suis infecting isolated human macrophages in the presence of syngeneic NK cells. We show that (i) NK cells impair the intramacrophagic development of B. suis, a phenomenon enhanced by NK cell activators, such as interleukin-2; (ii) NK cells cultured in the presence of infected macrophages are highly activated and secrete gamma interferon and tumor necrosis factor alpha; (iii) impairment of bacterial multiplication inside infected cells is marginally associated with the cytokines produced during the early phase of macrophage-NK cell cocultures; (iv) direct cell-to-cell contact is required for NK cells to mediate the inhibition of B. suis development; and (v) inhibition of B. suis development results from an induction of NK cell cytotoxicity against infected macrophages. Altogether, these findings show that NK cells could participate early in controlling the intramacrophagic development of B. suis in humans. It seems thus reasonable to hypothesize a role for NK cells in the control of human brucellosis. However, by impairing the activity of these cells in the acute phase of the illness, the pathogen should avoid this control.

Natural-killer cells and dendritic cells: “l'union fait la force”

Blood ◽  
2005 ◽  
Vol 106 (7) ◽  
pp. 2252-2258 ◽  
Author(s):  
Thierry Walzer ◽  
Marc Dalod ◽  
Scott H. Robbins ◽  
Laurence Zitvogel ◽  
Eric Vivier
Keyword(s):  
Dendritic Cells ◽  
Nk Cells ◽  
Natural Killer ◽  
Cell Activation ◽  
Nk Cell ◽  
Interleukin 12 ◽  
Cell Contact ◽  
Ifn Γ

AbstractSeveral recent publications have focused on the newly described interactions between natural-killer (NK) cells and dendritic cells (DCs). Activated NK cells induce DC maturation either directly or in synergy with suboptimal levels of microbial signals. Immature DCs appear susceptible to autologous NK-cell-mediated cytolysis while mature DCs are protected. NK-cell-induced DC activation is dependent on both tumor necrosis factor-α (TNF-α)/interferon-γ (IFN-γ) secretion and a cell-cell contact involving NKp30. In vitro, interleukin-12 (IL-12)/IL-18, IL-15, and IFN-α/β production by activated DCs enhance, in turn, NK-cell IFN-γ production, proliferation, and cytotoxic potential, respectively. In vivo, NK-cell/DC interactions may occur in lymphoid organs as well as in nonlymphoid tissues, and their consequences are multiple. By inducing DC activation, NK-cell activation induced by tumor cells can indirectly promote antitumoral T-cell responses. Reciprocally, DCs activated through Toll-like receptors (TLRs) induce potent NK-cell activation in antiviral responses. Thus, DCs and NK cells are equipped with complementary sets of receptors that allow the recognition of various pathogenic agents, emphasizing the role of NK-cell/DC crosstalk in the coordination of innate and adaptive immune responses.

IPH2101, a Novel Anti-Inhibitory KIR Monoclonal Antibody, and Lenalidomide Combine to Enhance the Natural Killer (NK) Cell Versus Multiple Myeloma (MM) Effect.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3870-3870 ◽  
Author(s):  
Don Benson ◽  
Courtney E Bakan ◽  
Shuhong Zhang ◽  
Lana Alghothani ◽  
Jing Liang ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Phase 1 ◽  
Granzyme B ◽  
Cell Activity ◽  
Target Cells ◽  
Nk Cell Activity ◽  
Immune Complex Formation

Abstract Abstract 3870 Poster Board III-806 Background NK cell activity against tumor cells is regulated by a balance of inhibitory and activating signals mediated by receptors on NK cells that recognize inhibitory and activating ligands expressed by cancer cells. IPH2101 (1-7F9) is a novel monoclonal anti-inhibitor KIR blocking antibody that has been shown to augment NK cell function against MM targets. Moreover, lenalidomide has been shown to expand and activate NK cells in vivo and in vitro. We have previously reported that the combination of IPH2101 and lenalidomide enhances NK cell mediated cytotoxicity against MM cells compared to each agent alone (Zhang et al., AACR 2009). We expand our studies to investigate potential mechanisms for the enhancement of NK cell activity by the combination of IPH2101 and lenalidomide. Methods The effects of IPH2101 and lenalidomide alone and in combination were studied using primary human NK cells from healthy donors as well as from MM patients. The MM cell lines U266 and RPMI 8226 as well as primary tumor cells from marrow aspirates of MM patients served as target cells. The effect of lenalidomide on MM activating and inhibitory ligand expression was studied by flow cytometry. NK cell trafficking was investigated with standard transwell plate migration assay. Immune complex formation between NK cell effectors and MM tumor targets was characterized by flow cytometry in control conditions and with NK cells pre-treated with IPH2101 and lenalidomide. The effects of IPH2101 and lenalidomide were studied regarding interferon-gamma and granzyme B production by ELISPOT and target-specific cytotoxicity studies were conducted to complement effector-based assays. Results IPH2101 (30 ug/ml) significantly enhanced cytotoxicity against U266 cells and primary MM tumor cells by both purified NK cells at effector:target (E:T) ratios of 10:1 or less, and also of freshly isolated peripheral blood mononuclear cells (PBMC) at E:T ratios of 60:1 or less, from more than 10 random donors. In addition, treatment of PBMC with 5-10 μmol/L lenalidomide for 72h without interleukin (IL)-2 increased NK cell lysis of U266. Treatment of PBMC from normal donors did not enhance the expression of the NK receptors KIR, NKG2D, NCR, TRAIL, and DNAM-1. Incubation of U266 cells with lenalidomide (5 uM) for 3-5 days resulted in significant enhancement of cytotoxicity by normal donor NK cells. This was associated with upregulation of the activating ligands, MICA, ULBP-2, DR4, and CD112. Using blocking antibodies to NKG2D, TRAIL, and DNAM-1, lenalidomide enhancement of MM cell killing was abrogated indicating the importance of the modulation of the ligands to the latter receptors by lenalidomide. Although IPH2101 and lenalidomide did not significantly increase NK cell migration into normal media, migration was enhanced 2.98-fold (+/− 0.36, p < 0.05) towards U266 cell targets (n= 3, p < 0.05) and MM patient serum 3.2-fold (+/− 0.4, n=3, p < 0.05). IPH2101 and lenalidomide also led to a 2.3-fold (+/− 0.43, p < 0.05) increase in immune complex formation between NK cells and MM tumor cells. IPH2101 and lenalidomide also augmented NK cell interferon gamma production against MM (control mean 303 spots/well +/− 13 versus 525 +/− 83, n=3, p < 0.05) and granzyme B production (control mean 115 +/− 98 versus 449 +/−72, n=3, p < 0.05). Importantly, in all experiments described herein, the effects of IPH2101 and lenalidomide together were greater than either agent alone. Conclusions Taken together, our data suggest that IPH2101 and lenalidomide may exert complementary mechanisms on both effector and target cells to enhance NK cell mediated killing of MM cells. Moreover, these agents have no predicted clinical cross-toxicities. A single-agent phase 1 clinical trial of IPH2101 has shown the mAb to be safe and well tolerated in MM patients. These findings support a phase 1/2 clinical trial of IPH2101 with lenalidomide as a first dual-innate immunotherapy for patients with MM. Disclosures: Andre: Innate Pharma: Employment. Squiban:Innate pharma: Employment. Romagne:Innate Pharma: Employment.

scholarly journals Dose of Retroviral Infection Determines Induction of Antiviral NK Cell Responses

2017 ◽  
Vol 91 (22) ◽  
Author(s):  
Elisabeth Littwitz-Salomon ◽  
Simone Schimmer ◽  
Ulf Dittmer
Keyword(s):  
Nk Cells ◽  
Cell Activation ◽  
Nk Cell ◽  
Cell Activity ◽  
High Dose ◽  
Nk Cell Activity ◽  
Retroviral Infection ◽  
Cell Functions ◽  
Virus Dose ◽  
Antiviral Activities

ABSTRACT Natural killer (NK) cells are part of the innate immune system and recognize virus-infected cells as well as tumor cells. Conflicting data about the beneficial or even detrimental role of NK cells in different infectious diseases have been described previously. While the type of pathogen strongly influences NK cell functionality, less is known about how the infection dose influences the quality of a NK cell response against retroviruses. In this study, we used the well-established Friend retrovirus (FV) mouse model to investigate the impact of virus dose on the induction of antiviral NK cell functions. High-dose virus inoculation increased initial virus replication compared to that with medium- or low-dose viral challenge and significantly improved NK cell activation. Antiviral NK cell activity, including in vivo cytotoxicity toward infected target cells, was also enhanced by high-dose virus infection. NK cell activation following high-dose viral challenge was likely mediated by activated dendritic cells (DCs) and macrophages and the NK cell-stimulating cytokines interleukin 15 (IL-15) and IL-18. Neutralization of these cytokines decreased NK cell functions and increased viral loads, whereas IL-15 and IL-18 therapy improved NK cell activity. Here we demonstrate that virus dose positively correlates with antiviral NK cell activity and function, which are at least partly driven by IL-15 and IL-18. Our results suggest that NK cell activity may be therapeutically enhanced by administering IL-15 and IL-18 in virus infections that inadequately activate NK cells. IMPORTANCE In infections with retroviruses, like HIV and FV infection of mice, NK cells clearly mediate antiviral activities, but they are usually not sufficient to prevent severe pathology. Here we show that the initial infection dose impacts the induction of an antiviral NK cell response during an acute retroviral infection, which had not investigated before. High-dose infection resulted in a strong NK cell functionality, whereas no antiviral activities were detected after low- or medium-dose infection. Interestingly, DCs and macrophages were highly activated after high-dose FV challenge, which corresponded with increased levels of NK cell-stimulating cytokines IL-15 and IL-18. IL-15 and IL-18 neutralization decreased NK cell functions, whereas IL-15 and IL-18 therapy improved NK cell activity. Here we show the importance of cytokines for NK cell activation in retroviral infections; our findings suggest that immunotherapy combining the well-tolerated cytokines IL-15 and IL-18 might be an interesting approach for antiretroviral treatment.

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