scholarly journals Tumor hypoxia impairs NK cell cytotoxicity through SHP-1-mediated attenuation of STAT3 and ERK signaling pathways

2019 ◽  
Author(s):  
Yanmeng Wang ◽  
Rui Teng ◽  
Nan Lv ◽  
Ramone A. Williamson ◽  
Lei Lei ◽  
...  
Keyword(s):  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Tyrosine Phosphatase ◽  
Tumor Hypoxia ◽  
Specific Inhibitor ◽  
Dependent Manner ◽  
Cell Cytotoxicity ◽  
Nk Cell Cytotoxicity ◽  
Anti Tumor Activity

Abstract Natural killer (NK) cells are innate immune effectors with potent anti-tumor activity. Nonetheless, tumor cells have the ability to create an immunosuppressive microenvironment, thereby escaping from immune surveillance. Although accumulating evidence indicates that microenvironmental hypoxia plays an important role in favoring tumor development and immune evasion, it is still unclear how hypoxia directly impairs NK cell anti-tumor activity. In this study, we confirmed that hypoxic NK cells show significantly lower cytotoxicity against tumor cells. Consistent with this, we also found that the reduction in NK cell cytotoxicity resulting from hypoxia is related to the lower expression of granzyme B, IFN-γ, degranulation marker CD107a, as well as killer activation receptors including NKp30, NKp46, and NKG2D on NK cells. More importantly, we further demonstrated that a reduction in the phosphorylation levels of ERK and STAT3 secondary to hypoxia are tightly associated with the attenuated NK cell cytotoxicity. Focusing on the mechanism responsible for reducing phosphorylation levels of ERK and STAT3, we revealed that the activation of protein tyrosine phosphatase SHP-1 (src homology region 2 domain-containing phosphatase-1) following hypoxia may play an essential role in this process. When knocking down SHP-1 or blocking its activity using a specific inhibitor TPI-1, we were able to partially restore NK cell cytotoxicity under hypoxia. Taken together, we demonstrated that hypoxia can impair NK cell cytotoxicity by decreasing the phosphorylation levels of ERK and STAT3 in a SHP-1 dependent manner. Therefore, targeting SHP-1 could provide an approach to enhance NK cell-based tumor immunotherapy.

scholarly journals Tumor hypoxia impairs NK cell cytotoxicity through SHP-1-mediated attenuation of STAT3 and ERK signaling pathways

2019 ◽  
Author(s):  
Yanmeng Wang ◽  
Rui Teng ◽  
Nan Lv ◽  
Ramone A. Williamson ◽  
Lei Lei ◽  
...  
Keyword(s):  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Tyrosine Phosphatase ◽  
Tumor Hypoxia ◽  
Specific Inhibitor ◽  
Dependent Manner ◽  
Cell Cytotoxicity ◽  
Nk Cell Cytotoxicity ◽  
Anti Tumor Activity

Abstract Natural killer (NK) cells are innate immune effectors with potent anti-tumor activity. Nonetheless, tumor cells have the ability to create an immunosuppressive microenvironment, thereby escaping from immune surveillance. Although accumulating evidence indicates that microenvironmental hypoxia plays an important role in favoring tumor development and immune evasion, it is still unclear how hypoxia directly impairs NK cell anti-tumor activity. In this study, we confirmed that hypoxic NK cells show significantly lower cytotoxicity against tumor cells. Consistent with this, we also found that the reduction in NK cell cytotoxicity resulting from hypoxia is related to the lower expression of granzyme B, IFN-γ, degranulation marker CD107a, as well as killer activation receptors including NKp30, NKp46, and NKG2D on NK cells. More importantly, we further demonstrated that a reduction in the phosphorylation levels of ERK and STAT3 secondary to hypoxia are tightly associated with the attenuated NK cell cytotoxicity. Focusing on the mechanism responsible for reducing phosphorylation levels of ERK and STAT3, we revealed that the activation of protein tyrosine phosphatase SHP-1 (src homology region 2 domain-containing phosphatase-1) following hypoxia may play an essential role in this process. When knocking down SHP-1 or blocking its activity using a specific inhibitor TPI-1, we were able to partially restore NK cell cytotoxicity under hypoxia. Taken together, we demonstrated that hypoxia can impair NK cell cytotoxicity by decreasing the phosphorylation levels of ERK and STAT3 in a SHP-1 dependent manner. Therefore, targeting SHP-1 could provide an approach to enhance NK cell-based tumor immunotherapy.

scholarly journals Hypoxia Impairs NK Cell Cytotoxicity through SHP-1-Mediated Attenuation of STAT3 and ERK Signaling Pathways

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Rui Teng ◽  
Yanmeng Wang ◽  
Nan Lv ◽  
Dan Zhang ◽  
Ramone A. Williamson ◽  
...  
Keyword(s):  
Antitumor Activity ◽  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Tyrosine Phosphatase ◽  
Immune Surveillance ◽  
Specific Inhibitor ◽  
Dependent Manner ◽  
Cell Cytotoxicity ◽  
Nk Cell Cytotoxicity

Natural killer (NK) cells are innate immune effectors with potent antitumor activity. However, tumor cells can create an immunosuppressive microenvironment to escape immune surveillance. Although accumulating evidence indicates that microenvironmental hypoxia plays an important role in favoring tumor development and immune evasion, it remains unclear by what means hypoxia directly impairs NK cell antitumor activity. In this study, we confirmed that hypoxic NK cells showed significantly lower cytotoxicity against tumor cells. Consistent with this finding, we found that the reduction in NK cell cytotoxicity resulting from hypoxia correlated to the lower expression of granzyme B, IFN-γ, and degranulation marker CD107a, as well as activating receptors including NKp30, NKp46, and NKG2D expressed on the surface of NK cells. More importantly, we further demonstrated that a reduction in the phosphorylation levels of ERK and STAT3 secondary to hypoxia was strongly associated with the attenuated NK cell cytotoxicity. Focusing on the mechanism responsible for reduced phosphorylation levels of ERK and STAT3, we reveal that the activation of protein tyrosine phosphatase SHP-1 (Src homology region 2 domain-containing phosphatase-1) following hypoxia might play an essential role in this process. By knocking down SHP-1 or blocking its activity using a specific inhibitor TPI-1, we were able to partially restore NK cell cytotoxicity under hypoxia. Taken together, we demonstrate that hypoxia could impair NK cell cytotoxicity by decreasing the phosphorylation levels of ERK and STAT3 in a SHP-1-dependent manner. Therefore, targeting SHP-1 could provide an approach to enhance NK cell-based tumor immunotherapy.

In Vitro and In Vivo Sensitization of Malignant Cells to Autologous Natural Killer Cell Cytotoxicity Following Exposure to Bortezomib.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 925-925 ◽  
Author(s):  
Andreas Lundqvist ◽  
Kristy Greeneltch ◽  
Maria Berg ◽  
Shivani Srivastava ◽  
Nanae Harashima ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Cell Cytotoxicity ◽  
Malignant Cells ◽  
Nk Cell Cytotoxicity ◽  
Tumor Death

Abstract Killer IgG like receptor (KIR) inactivation of NK cells by self HLA molecules has been proposed as a mechanism through which malignant cells evade host NK cell-mediated immunity. To overcome this limitation, we sought to develop a method to sensitize the patient’s tumor to autologous NK cell cytotoxicity. The proteasome inhibitor bortezomib has recently been shown to enhance the activity of tumor death receptors. We found that exposure of a variety of different leukemia, lymphoma and solid tumor cancer cell lines to sub-apoptotic doses of bortezomib sensitized tumor cells in vitro to lysis by allogeneic NK cells. Importantly, this sensitizing effect also occurs with autologous NK cells normally rendered inactive via tumor KIR ligands; NK cells expanded from patients with metastatic renal cell carcinoma were significantly more cytotoxic against the patient’s own autologous tumor cells when pretreated with bortezomib compared to untreated tumors. This sensitization to autologous NK cell killing was also observed in vivo in two different murine tumor models. A significant delay in tumor growth in C57BL/6 mice bearing LLC1 tumors (figure) and a delay in tumor growth and a significant prolongation (p<0.01) in survival were observed in RENCA tumor bearing Balb/c mice treated with bortezomib and syngeneic NK cell infusions compared to untreated mice or animals treated with bortezomib alone or NK cells alone. An investigation into the mechanism through which NK cell cytotoxicity was potentiated revealed bortezomib enhanced the activity of tumor death receptor-dependent and -independent apoptotic pathways. More specifically, bortezomib sensitized human and murine tumor cells to TRAIL and perforin/granzyme mediated NK cell cytotoxicity respectively. These observations suggest that pretreatment of malignant cells with bortezomib could be used as a strategy to override NK cell inhibition via tumor KIR ligands, thus potentiating the activity of adoptively infused autologous NK cells. A clinical trial evaluating the safety and anti-tumor efficacy of adoptively infused autologous NK cells in patients with advanced malignancies with and without tumor sensitization using bortezomib is currently being explored. Figure: Tumor growth in LLC1 bearing C57BL/6 mice. Fourteen days following s.c. injection of 3x105 LLC1 tumor cells, mice received 15μg (i.p) bortezomib and/or an adoptive infusion of 1x106 NK cells from C57BL/6 mice (i.v) given on day 15. Each dot represents the tumor volume of individual mice measured on day 28 post tumor injection. Tumors were significantly smaller in mice treated with bortezomib followed by NK cells compared to controls or mice that received either NK cells alone or bortezomib alone (p<0.04 for all groups). Figure:. Tumor growth in LLC1 bearing C57BL/6 mice. . / Fourteen days following s.c. injection of 3x105 LLC1 tumor cells, mice received 15μg (i.p) bortezomib and/or an adoptive infusion of 1x106 NK cells from C57BL/6 mice (i.v) given on day 15. Each dot represents the tumor volume of individual mice measured on day 28 post tumor injection. Tumors were significantly smaller in mice treated with bortezomib followed by NK cells compared to controls or mice that received either NK cells alone or bortezomib alone (p<0.04 for all groups).

Novel monoclonal antibody that enhances natural killer (NK) cell cytotoxicity against multiple myeloma (MM): Preclinical data and interim phase I clinical trial results

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. 3032-3032
Author(s):  
D. M. Benson ◽  
F. Romagne ◽  
P. Squiban ◽  
N. Wagtmann ◽  
S. Farag ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Phase 1 ◽  
Cell Maturation ◽  
Cell Cytotoxicity ◽  
Post Dose ◽  
Ifn Γ ◽  
Nk Cell Cytotoxicity

3032 Background: MM is increasing in incidence and remains incurable. NK cells have modest killing activity against MM cells in part because of inhibitory signals from HLA class 1 antigens which act via the KIR receptors on NK cells. A novel anti-KIR blocking antibody (1–7F9 named IPH 2101) enhances patient NK cell cytotoxicity against autologous MM tumor cells in vitro and appears safe in an ongoing phase 1 clinical trial. Methods: NK cells from healthy controls or patients were pre-treated with IPH 2101 or IgG4 isotype control and co-cultured with MM cell lines or autologous MM tumor targets. NK cell production of interferon-gamma (IFN-γ) or granzyme B (GrB) were measured by ELISPOT. An open-label, single-agent, phase 1 dose escalation study of IPH 2101 is being conducted in patients with relapsed/refractory MM. KIR binding, pharmacokinetics, pharmacodynamics, effects on NK cell maturation, and biological effects of IPH 2101 are being monitored in all patients. Results: At an effector to target (E:T) ratio of 1:1, IPH 2101 significantly enhances NK cell IFN-γ release against MM targets (mean 33 spots/well ± 12, SEM vs. 11 ± 0.3, p = 0.005). At an E:T ratio of 10:1, IPH 2101 enhances NK cell cytotoxicity, by GrB release, of patient NK cells against autologous MM tumor cells (mean 111 spots/well ± 14, SEM vs 56 ± 10, p = 0.002). By Western blot, IPH 2101 may reduce levels of src, a kinase known to be involved in inhibitory KIR signaling. Dose escalation in the phase 1 study has been completed from 0.0003 mg/kg to 0.075 mg/kg in 14 evaluable patients. At the highest dose tested, KIR occupancy has been detected at a mean 95% ± 1.4 at 2 hours post dose, lasting up to 56% ± 18 during 2 weeks post dose. At this dose level, PK data show good correspondence with previous modeling activity. No deleterious effect on NK cell maturation has been seen. IPH 2101 has been well tolerated to date. Conclusions: IPH 2101 improves autologous NK cell killing of MM tumor cells by blocking inhibitory KIR. In the ongoing clinical trial, the antibody appears safe and well tolerated at the doses tested. This immunotherapeutic approach may hold promise as treatment for MM and further study is warranted. [Table: see text]

scholarly journals Pseudomonas aeruginosa Infection Impairs NKG2D-Dependent NK Cell Cytotoxicity through Regulatory T-Cell Activation

2020 ◽  
Vol 88 (12) ◽  
Author(s):  
Mickael Vourc’h ◽  
Gaelle David ◽  
Benjamin Gaborit ◽  
Alexis Broquet ◽  
Cedric Jacqueline ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Nk Cells ◽  
Natural Killer ◽  
Antitumor Immunity ◽  
Nk Cell ◽  
Dependent Manner ◽  
Cell Cytotoxicity ◽  
Content Type ◽  
Cytotoxic Response ◽  
Nk Cell Cytotoxicity

ABSTRACT Natural killer (NK) cells play a key role in both antibacterial and antitumor immunity. Pseudomonas aeruginosa infection has already been reported to alter NK cell functions. We studied in vitro the effect of P. aeruginosa on NK cell cytotoxic response (CD107a membrane expression) to a lymphoma cell line. Through positive and negative cell sorting and adoptive transfer, we determined the influence of monocytes, lymphocytes, and regulatory T cells (Treg) on NK cell function during P. aeruginosa infection. We also studied the role of the activating receptor natural killer group 2D (NKG2D) in NK cell response to B221. We determined that P. aeruginosa significantly altered both cytotoxic response to B221 and NKG2D expression on NK cells in a Treg-dependent manner and that the NKG2D receptor was involved in NK cell cytotoxic response to B221. Our results also suggested that during P. aeruginosa infection, monocytes participated in Treg-mediated NK cell alteration. In conclusion, P. aeruginosa infection impairs NK cell cytotoxicity and alters antitumor immunity. These results highlight the strong interaction between bacterial infection and immunity against cancer.

Mimicking An Induced Self Phenotype by Coating Lymphomas with the Nkp30-Ligand B7-H6 Promotes Antitumoral Natural Killer Cell Cytotoxicity

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 103-103
Author(s):  
Christian Kellner ◽  
Tina Maurer ◽  
Daniela Hallack ◽  
Roland Repp ◽  
Jan G.J. van de Winkel ◽  
...  
Keyword(s):  
Cell Surface ◽  
Fusion Protein ◽  
Nk Cells ◽  
Natural Killer ◽  
Tumor Cells ◽  
Cell Lines ◽  
Surface Density ◽  
Nk Cell ◽  
Cell Cytotoxicity ◽  
Nk Cell Cytotoxicity

Abstract Abstract 103 Induced self-expression of ligands for stimulatory receptors facilitates natural killer (NK) cell-mediated elimination of stressed cells. Stimulatory receptors include Natural killer group 2 member D (NKG2D) and Nkp30, which control cytotoxic activities of NK cells and are important in immune surveillance against tumors. Specific modulation of NK cell cytotoxicity by selectively increasing the surface density of activating ligands on tumor cells may therefore represent an innovative approach to develop novel treatment strategies. A novel fusion protein was designed to enhance NK cell-based immune responses against B-lineage lymphomas by increasing the cell surface density of the recently identified Nkp30 ligand B7-H6 on tumor cells. The recombinant protein consisted of the ectodomain of B7-H6 and a CD20-directed human single chain fragment variable (scFv) as targeting device. The resulting fully-human protein designated B7-H6:CD20-scFv was eukaryotically expressed and purified by affinity chromatography. B7-H6:CD20-scFv indeed had bifunctional properties as reflected by its ability to simultaneously bind to the CD20 antigen and to the Nkp30 receptor. CD20-positive lymphoma cells opsonized with B7-H6:CD20-scFv alerted human NK cells as indicated by upregulated surface expression levels of the early inducible activation marker CD69. Activation was accompanied by induced CD107a cell surface exposure indicating enhanced NK cell degranulation. In cytotoxicity assays using human NK cells from healthy donors as effector cells, B7-H6:CD20-scFv triggered killing of lymphoma-derived B-cell lines. B7-H6:CD20-scFv was active in a strictly antigen-specific manner as demonstrated by blocking experiments and was not able to mediate killing of cell lines not expressing the CD20 target antigen. B7-H6:CD20-scFv mediated killing of lymphoma cells in a dose-dependent manner starting at nanomolar concentrations. Target cell death induced by B7-H6:CD20-scFv occurred by apoptosis and involved caspase cleavage. Moreover, B7-H6:CD20-scFv induced NK cell-mediated lysis of fresh tumor cells from 8/8 CLL and 5/5 MCL patients with variable CD20 expression levels. In comparison to ULBP2:CD20-scFv, a similarly constructed fusion protein of the NKG2D ligand ULBP2 and a CD20-directed scFv, the B7-H6:CD20-scFv had a lower potency (EC50 values for B7-H6:CD20-scFv and ULBP2:CD20-scFv were 100 and 4 nM, respectively) but nevertheless achieved similar maximum extents of lysis. Interestingly, when B7-H6:CD20-scFv was added together with ULBP2:CD20-scFv to a mixture of NK cells and target cells, synergistic cytotoxic effects were induced. The combined treatment resulted in a higher percentage of NK cells that responded and exposed the degranulation marker CD107a on the cell surface in comparison to samples containing only one of the two agents. As a consequence a significantly higher extent of lysis was achieved. These results strongly indicate a co-operation between Nkp30 and NKG2D signalling which use different downstream signalling pathways. Thus, mimicking an induced self phenotype of tumors by coating lymphomas with B7-H6:CD20-scFv either alone or in combination with molecules triggering NKG2D may provide an innovative strategy to enhance specific anti-tumoral NK cell cytotoxicity. Disclosures: van de Winkel: Genmab: Employment. Parren:Genmab BV: Employment. Peipp:Genmab: Consultancy.

Neutralization of Tumor-Derived Soluble Glucocorticoid-Induced TNF-Related Protein (GITR) Ligand Present in Cancer Patient Sera Increases Anti-Tumor Reactivity of NK Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 314-314 ◽  
Author(s):  
Katrin M. Baltz ◽  
Matthias Krusch ◽  
Tina Baessler ◽  
Anita Bringmann ◽  
Lothar Kanz ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Nk Cells ◽  
Tumor Cells ◽  
Nk Cell ◽  
Cell Cytotoxicity ◽  
Related Protein ◽  
Effector Functions ◽  
Ifn Γ ◽  
Nk Cell Cytotoxicity ◽  
Cell Effector

Abstract Glucocorticoid-induced TNF-related protein (GITR) and its ligand (GITRL) are members of the TNF/TNF receptor (TNFR) superfamily, which mediates multiple cellular functions including proliferation, differentiation, and cell death. Recently we reported that NK cells express GITR while tumor cells express GITRL, and GITR-GITRL interaction downregulates NK cell-mediated anti-tumor immunity (Baltz et al., FASEB J 2007). Many TNF family members are released as soluble forms, which affects cell-cell interactions by reduction of ligand density and distally modulates effector cells bearing the respective receptor. Here we report that human tumor cells spontaneously release a soluble form of GITRL (sGITRL), which can be detected in tumor cell culture supernatants by ELISA (detection limit 0.01ng/ml). We demonstrated that NK cell cytotoxicity and IFN-γ production in cocultures with the tumor cell lines SK-Mel (Melanoma), PC-3 (prostate), HCT116 (colon), and LX-1 (lung) were significantly (both p<0.01, Mann-Whitney U-test) and concentration dependently reduced (up to 50%) by tumor-derived sGITRL, and NK cell effector functions could be restored by neutralization of sGITRL using a GITR-Fc fusion protein. While tumor-derived GITRL did not induce apoptosis in NK cells, it diminished nuclear localized RelB indicating that sGITRL negatively modulates NK cell NF-κB activity. Furthermore, we demonstrate that significantly elevated sGITRL levels (mean 0.4ng/ml, range from 0.01 to 3.5ng/ml) were contained in 40 out of 50 sera of patients with various cancers (colon, lung and germ line), while sera of healthy volunteers (n=8) contained no detectable levels of sGITRL. Addition of sGITRL containing patient sera to cocultures of NK cells and GITRL-negative tumor cells significantly reduced NK cell cytotoxicity and IFN-γ production about 30% and 45%, respectively (both p<0.05, Mann-Whitney U-test). Again the inhibitory effects of sGITRL on NK cell effector functions could be completely restored by neutralization of sGITRL with GITR-Fc. The strong correlation of tumor incidence and elevated sGITRL levels clearly suggests that sGITRL is released at significant amounts from malignant cells in vivo and may reduce immune surveillance of human tumors. Our data indicate that determination of sGITRL levels may be implemented as an immunological diagnostic marker in tumor patients, and GITRL-neutralization may be employed in therapeutic strategies like adoptive NK cell transfer.

scholarly journals WF10 Stimulates NK Cell Cytotoxicity by Increasing LFA-1-Mediated Adhesion to Tumor Cells

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Louisa Kühne ◽  
Mathias Konstandin ◽  
Yvonne Samstag ◽  
Stefan Meuer ◽  
Thomas Giese ◽  
...  
Keyword(s):  
Nk Cells ◽  
Cell Activation ◽  
Nk Cell ◽  
Killer Cell ◽  
Target Cells ◽  
Dependent Manner ◽  
Cell Cytotoxicity ◽  
Natural Killer Cell Cytotoxicity ◽  
Nk Cell Cytotoxicity

The redox-active chlorite-based drug WF10 (Immunokine) was shown to have modulatory effects on both the innate and adaptive immune systemin vitroandin vivo. Animal studies suggest that WF10 enhances immunity against tumors. One possible explanation for such an effect is that WF10 stimulates natural killer cell cytotoxicity against malignant cells. Here, we show that WF10 regulates human NK cell cytotoxicity in a time-dependent manner, following an S-shaped kinetic with an initial stimulation of activity followed by a decrease in activity relative to the untreated controls. WF10 does not activate NK cells on its own but co-stimulates NK cell activation mediated by different activating receptors. This is mediated by enhancing NK cell adhesion to target cells through promoting the activation of the integrin LFA-1. These data demonstrate a direct effect of WF10 on the cytotoxicity of human NK cells.

scholarly journals Applying CRISPR-based genetic screens to identify drivers of tumor-cell sensitivity towards NK-cell attack

2019 ◽  
Author(s):  
Klara Klein ◽  
Tim Wang ◽  
Eric S. Lander ◽  
Marcus Altfeld ◽  
Wilfredo F. Garcia-Beltran
Keyword(s):  
Tumor Cell ◽  
Nk Cells ◽  
Tumor Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Target Cells ◽  
Cell Cytotoxicity ◽  
Genetic Screens ◽  
A Genome ◽  
Nk Cell Cytotoxicity

ABSTRACTNatural killer (NK) cells distinguish cancer cells from healthy cells using an array of germline-encoded receptors that interact with ligands expressed on target cells. A balance of inhibitory and activating signals transduced by these receptors regulate NK cell function to provide anti-tumor immunity while maintaining self-tolerance. However, knowledge of the spectrum of factors regulating NK-cell-mediated cytotoxicity, including the contribution of specific ligands and regulatory mechanisms for their expression on tumor cells, remains incomplete. Here, we apply a genome-wide loss-of-function screen in tumor cells using CRISPR/Cas9 technology to identify the factors that promote NK-cell cytotoxicity towards tumor cells. We established the drivers of tumor-cell sensitivity towards NK-cell attack (TuSeNKA) screening approach using the chronic myeloid leukemia (CML) cell line, K562. Interestingly, we identified B7H6, the ligand for the activating NK cell receptor NKp30, as the single factor whose loss resulted in increased resistance of K562 cells towards NK cells. Our study shows that combination of CRISPR-based genetic screens with NK-cell cytotoxicity assays is a valuable tool for identifying functionally relevant NK cell-tumor cell interactions, paving the way for further investigations that unravel the complexity of signals that promote NK-cell recognition of transformed cells and develop therapies that target these modes of tumor-cell killing.

scholarly journals NK cell activation in visceral leishmaniasis requires TLR9, myeloid DCs, and IL-12, but is independent of plasmacytoid DCs

2007 ◽  
Vol 204 (4) ◽  
pp. 893-906 ◽  
Author(s):  
Ulrike Schleicher ◽  
Jan Liese ◽  
Ilka Knippertz ◽  
Claudia Kurzmann ◽  
Andrea Hesse ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Nk Cells ◽  
Cell Activation ◽  
Nk Cell ◽  
Dependent Manner ◽  
Cell Cytotoxicity ◽  
Ifn Γ ◽  
Nk Cell Cytotoxicity

Natural killer (NK) cells are sentinel components of the innate response to pathogens, but the cell types, pathogen recognition receptors, and cytokines required for their activation in vivo are poorly defined. Here, we investigated the role of plasmacytoid dendritic cells (pDCs), myeloid DCs (mDCs), Toll-like receptors (TLRs), and of NK cell stimulatory cytokines for the induction of an NK cell response to the protozoan parasite Leishmania infantum. In vitro, pDCs did not endocytose Leishmania promastigotes but nevertheless released interferon (IFN)-α/β and interleukin (IL)-12 in a TLR9-dependent manner. mDCs rapidly internalized Leishmania and, in the presence of TLR9, produced IL-12, but not IFN-α/β. Depletion of pDCs did not impair the activation of NK cells in L. infantum–infected mice. In contrast, L. infantum–induced NK cell cytotoxicity and IFN-γ production were abolished in mDC-depleted mice. The same phenotype was observed in TLR9−/− mice, which lacked IL-12 expression by mDCs, and in IL-12−/− mice, whereas IFN-α/β receptor−/− mice showed only a minor reduction of NK cell IFN-γ expression. This study provides the first direct evidence that mDCs are essential for eliciting NK cell cytotoxicity and IFN-γ release in vivo and demonstrates that TLR9, mDCs, and IL-12 are functionally linked to the activation of NK cells in visceral leishmaniasis.

Sign in / Sign up

Export Citation Format

Share Document