The FLT3-Inhibitors Midostaurin, Sunitinib, Sorafenib, and TKI258 Differentially Affect NK Cell-Mediated Immunesurveillance of Acute Myeloid Leukemia.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3785-3785
Author(s):  
Julia Salih ◽  
Lothar Kanz ◽  
Helmut R Salih ◽  
Matthias Krusch
Keyword(s):  
Nk Cells ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Immune Surveillance ◽  
Leukemia Cells ◽  
Target Cells ◽  
Cell Reactivity ◽  
Flt3 Inhibitors ◽  
Ifn Γ

Abstract Abstract 3785 Poster Board III-721 FLT3 is a receptor tyrosine kinase with an important role in hematopoietic progenitor cell survival and proliferation. The discovery of internal tandem duplication mutations (ITD) in FLT3 was a major breakthrough in understanding the role of abnormally activated FLT3 in myeloid transformation. Between 15% and 34% of AML patients show FLT3-ITD mutations, and thus the inhibition of FLT3 in combination with chemotherapeutic agents may be a promising stragety in the treatment of Acute Myeloid Leukemia (AML). Several protein kinase inhibitors (PKI) targeting FLT3 like e.g. Midostaurin, Sunitinib, Sorafenib, and TKI258 are currently under preclinical and/or clinical evaluation (http://clinicaltrials.gov/ct2/results?term=AML+and+FLT3). Since those PKI, besides targeting their eponymous enzyme FLT3, also inhibit signaling via other molecules they may impair the effector function of various components of anti-tumor immunity. NK cells as part of the innate immune system play an important role in the immune surveillance of tumors due to their ability to directly kill target cells and to shape adaptive immune responses by secreting cytokines like IFN-γ. Clinical evidence for the particularly important role of NK cells in leukemia has recently been provided by studies of haploidentical stem cell transplantation (Ruggeri et al., Science 2002). We report here that CD107a expression as a surrogate marker for degranulation of NK cells within PBMC is inhibited by pharmacological concentrations of Sorafenib (10μg/ml) and Midostaurin (2μg/ml), but not by Sunitinib (200ng/ml) and TKI258 (125ng/ml). In line, pharmacological concentrations of Sunitinib and TKI258 did not affect NK cell cytotoxicity and IFN-γ production in cocultures with leukemia cells. Sorafenib and Midostaurin caused a clear concentration-dependent inhibition of NK cell cytokine production in response to target cells both in resting and in IL-2 activated state (92% and 66%, respectively at plasma peak levels). Furthermore, pharmacological concentrations of Sorafenib and Midostaurin also reduced lysis of leukemia cells by NK cells (54% and 58%, respectively, E:T ratio 10:1) and thus generally compromised NK cell reactivity. Analysis of NK cell signaling revealed that Sorafenib, but not Midostaurin decreased phosphorylation of PI3K and ERK which are important regulators of NK cell reactivity. Thus, Midostaurin inhibits yet undefined signaling events which are crucial for NK effector functions, but are independent of the “classical” PI3K – Rac – PAK – MEK – ERK pathway and are presently under study. Moreover, in light of the important role of NK cells in the immune surveillance of leukemia and the differential influence of clinically used FLT3-inhibitors on NK cell functions our data indicate that the choice and dosing of the most suitable compound in the treatment of AML requires further characterization and careful consideration. Disclosures: No relevant conflicts of interest to declare.

Role of CD137/4-1BB and Its Ligand in the NK Cell Mediated Immune Surveillance of Acute Myeloid Leukemia.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 880-880
Author(s):  
Tina Baessler ◽  
Matthias Krusch ◽  
Katrin M. Baltz ◽  
Benjamin J. Schmiedel ◽  
Helga M. Schmetzer ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Nk Cells ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Immune Surveillance ◽  
Cell Reactivity ◽  
Ifn Γ ◽  
Tnfr Superfamily ◽  
Acute Myeloid

Abstract NK cells play an important role in the reciprocal interaction of tumor cells with the immune system and participate in the surveillance and eradication of hematological malignancies including acute myeloid leukemia (AML). NK cell reactivity is governed by a balance of activating and inhibitory receptors including various members of the TNF receptor (TNFR) superfamily. The TNFR superfamily member CD137/4-1BB has been shown to stimulate proliferation and IFN-γ production, but not cytotoxicity of NK cells in mice. Surprisingly, yet nothing is known regarding the consequences of CD137-CD137 ligand (CD137L) interaction for NK cell reactivity in humans. In this study we demonstrate that CD56dimCD16+ but not CD56brightCD16− NK cells express CD137 upon stimulation with the activating cytokines IL-2 and IL-15 with peak expression between 48 and 60h. Furthermore, we found that 5 of 7 investigated AML cell lines and 16 of 51 (33%) primary AML cells of patients expressed substantial CD137L levels, while no CD137L expression was detected on CD34+ cells of healthy donors (n=5). CD137L expression was not restricted to a specific French-American-British (FAB) subtype, but was significantly (p<0.05, one-way ANOVA) associated with monocytic (FAB M4, M5) differentiation. In addition, no association with a particular cytogenetic abnormality or with expression of MHC class I was observed. Reverse signaling via CD137L into AML cells (n=10) significantly induced the release of the immunoregulatory cytokines IL-10 and TNF (both p<0.05, Mann-Whitney U-test). Surprisingly and in contrast to available data regarding the function of murine CD137, we found that in humans blocking CD137-CD137L interaction caused a significant increase in NK cell cytotoxicity and IFN-γ production about 50% (both p<0.05, Mann-Whitney U-test) in coculture assays with CD137L-expressing patient AML cells and AML cell lines. The inhibitory effect of CD137 on NK cell reactivity was further confirmed in cocultures of NK cells with CD137L-transfectants and by triggering CD137 with an agonistic monoclonal antibody. This indicates that CD137 mediates opposite effects in murine compared to human NK cells. Furthermore we conclude that CD137L expression substantially influences tumor immunoediting by AML cells and diminishes NK cell reactivity against AML.

RANKL Expressed by Acute Myeloid Leukemia Cells Impairs NK Cell-Mediated Immune Surveillance

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2164-2164
Author(s):  
Benjamin J Schmiedel ◽  
Constantin M Wende ◽  
Tina Baessler ◽  
Carolin Scheible ◽  
Stefan Wirths ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Nk Cells ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Immune Surveillance ◽  
Surface Protein ◽  
Leukemia Cells ◽  
Acute Myeloid Leukemia Cells ◽  
Acute Myeloid

Abstract Abstract 2164 NK cells play an important role in tumor immunosurveillance, especially of leukemia. Their reactivity is governed by various activating and inhibitory molecules expressed by their targets including multiple members of the TNF family. The TNF family member Receptor Activator of NF-κB ligand (RANKL) and its receptors RANK and osteoprotegerin (OPG) are key regulators of bone remodelling, but recently have also been shown to influence progression of hematopoetic malignancies. Here we studied the yet unkown role of the RANK/RANKL molecule system in NK cells and their reactivity against acute myeloid leukemia (AML). Primary leukemia cells from AML patients were found to substantially express RANKL mRNA and surface protein in 75% of the investigated cases (n=40). Reverse signaling via surface-expressed RANKL into AML blasts induced the release of soluble factors including the immunoregulatory cytokines TNF and IL-10, which impaired NK cell anti-tumor reactivity. Moreover, we observed upregulation of RANK on NK cells among PBMC of healthy donors upon exposure to IL-10. This was not caused by direct effects on NK cells, but was rather due to yet unidentified factors released by monocytes among the PBMC upon IL-10 exposure and could be prevented by the activating cytokine IL-2. Furthermore, functional experiments with NK cells and RANKL transfectants or RANKL-negative controls revealed that forward signaling into RANK-expressing NK cells by tumor-expressed RANKL also directly impaired NK cytotoxicity and IFN-γ production. In line, blocking RANK-RANKL interaction using anti-RANKL antibodies or RANK-Fc fusion protein increased cytotoxicity and cytokine production of allogenic NK cells in cultures with RANKL-positive primary AML cells. Our data indicate that RANKL expression enables immune evasion of leukemia cells both by directly inhibiting reactivity of RANK-expressing NK cells and by orchestrating a reciprocal interplay between AML cells, monocytes and NK cells resulting in an immunosuppressive cytokine milieu. Thus, therapeutic modulation of the RANK/RANKL system, e.g. with Denosumab/AMG162, which is presently being evaluated for treatment of both non-malignant and malignant osteolysis, holds promise to reinforce NK reactivity against hematopoietic malignancies. Disclosures: No relevant conflicts of interest to declare.

Expression and Immunomodulatory Function of RANKL in Leukemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 245-245
Author(s):  
Benjamin J Schmiedel ◽  
Tina Baessler ◽  
Miyuki Azuma ◽  
Lothar Kanz ◽  
Helmut R. Salih
Keyword(s):  
Nk Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Immune Surveillance ◽  
Leukemia Cells ◽  
Target Cells ◽  
Cytotoxic Lymphocytes ◽  
Hematopoietic Malignancies ◽  
Immunomodulatory Function

Abstract Abstract 245 The TNF family member RANKL and its receptors RANK and osteoprotegerin (OPG) are key regulators of bone remodelling, but have also been shown to influence progression of malignancies like breast cancer (Tan et al., Nature 2011), myeloma (Sordillo et al., Cancer 2003) and CLL (Secchiero et al. J Cell Physiol. 2006). NK cells are cytotoxic lymphocytes that play an important role in tumor immune surveillance especially of hematopoietic malignancies. Their reactivity is influenced by a variety of activating and inhibitory molecules expressed by their target cells including several members of the TNF family. Recently, we reported that RANK, upon interaction with RANKL which can be expressed by malignant hematopoietic cells, mediates signals that impair NK reactivity (Schmiedel et al., Blood 2010 116,21:893–893). Here we extended these analyses and comprehensively studied the expression and immunomodulatory function of RANKL in leukemia. Analysis of primary leukemia cells revealed substantial RANKL surface expression in a high proportion of the investigated cases (AML, 47 of 65 (72%); ALL, 16 of 21 (76%); CML, 6 of 10 (60%); CLL, all 54 (100%)). Signaling via surface-expressed RANKL into the malignant cells mediated the release of cytokines like TNF, IL-6, IL-8 and IL-10 which have been shown to act as autocrine and paracrine growth and survival factors in leukemia. Moreover, the factors released upon RANKL signaling upregulated RANK expression on NK cells. In line, NK cells from leukemia patients (n=75) displayed significantly (p<0.001, Mann-Whitney U-test) higher RANK expression compared to healthy controls (n=30) confirming our notion that RANK-RANKL interaction may contribute to leukemia pathophysiology. We further found that RANK-RANKL interaction, beyond directly inhibiting NK cell function via RANK, may contribute to evasion of leukemia cells from NK immunosurveillance by creating an NK inhibitory cytokine milieu. This was revealed by impaired cytotoxicity and degranulation in response to leukemia targets following exposure of the NK cells to the factors released upon RANKL signaling by leukemia cells. Notably, the RANKL-mediated cytokine release of leukemia cells could be disrupted by the clinically approved RANKL antibody Denosumab/AMG162. Thus, RANKL signaling may trigger a “vicious cycle” comprising of release of immunosuppressive cytokines and also upregulation of RANK on NK cells. The latter both directly inhibits NK reactivity and may result in augmented RANKL signaling into leukemia cells. Our data suggest that therapeutic modulation of the RANK/RANKL system e.g. with Denosumab/AMG162, which is approved for treatment of osteolysis, may be a promising strategy to reinforce NK reactivity against hematopoietic malignancies. Disclosures: No relevant conflicts of interest to declare.

Expression of Glucocorticoid-Induced TNF Receptor Ligand on Acute Myeloid Leukemia Cells Mediates the Release of Immunosuppressive Cytokines and Impairs NK Cell-Mediated Immune Surveillance.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1941-1941
Author(s):  
Matthias Krusch ◽  
Katrin M. Baltz ◽  
Tina Baessler ◽  
Mercedes Kloss ◽  
Ingrid Kumbier ◽  
...  
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
Nk Cells ◽  
Myeloid Leukemia ◽  
Cellular Proliferation ◽  
Nk Cell ◽  
Leukemia Cells ◽  
Tnf Receptor ◽  
Ifn Γ ◽  
Acute Myeloid

Abstract NK cells play an important role in the reciprocal interaction of tumor cells with the immune system and participate in the surveillance of hematological malignancies including acute myeloid leukemia (AML). Among the molecules influencing host-tumor interaction are many members of the TNF superfamily, which mediate multiple cellular functions including cellular proliferation, differentiation and cell death. The TNF family member Glucocorticoid-induced TNF Receptor (GITR) costimulates effector T cells, modulates apoptosis and nuclear factor kappa B and abrogates suppression of murine but not human regulatory T cells. Its cognate ligand GITRL has been found in various healthy tissues. Recently we reported that NK cells express GITR, while solid tumors express GITR ligand (GITRL), and GITR/GITRL interaction downregulates NK cell cytotoxicity and IFN-γ production. Here we analyzed the role of GITR and its ligand in AML. We report for the first time that GITRL is expressed on primary AML cells in 18 of 30 patients as determined by FACS and RT-PCR analysis. Reverse signaling through GITRL using a recombinant GITR-Ig fusion protein induces the release of the immunoregulatory cytokines IL-10 and TNF as determined by ELISA. GITRL-mediated cytokine production of AML cells is abrogated by inhibition of mitogen activated protein kinase (MAPK) pathways as demonstrated by addition of the specific p38 MAPK inhibitor SB202190, the specific JNK inhibitor SP600125 and the specific ERK Inhibitor II. Furthermore, binding of AML-expressed GITRL to GITR on NK cells downregulates cellular cytotoxicity and IFN-γ production in AML-NK cell cocultures, which can be overcome by addition of GITR-blocking antibodies as determined by cytotoxicity assays and ELISA. Thus, our data indicate that GITRL expression in AML substantially influences tumor immunoediting and enables the escape of leukemia cells from NK cell-mediated immunosurveillance.

scholarly journals Involvement of NFAT Transcription Factors in NK Cell Reactivity

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1344-1344 ◽  
Author(s):  
Kathrin Rothfelder ◽  
Melanie Märklin ◽  
Julia Wild ◽  
Daniela Dörfel ◽  
Lothar Kanz ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Nk Cells ◽  
Nk Cell ◽  
Inhibitory Effect ◽  
Target Cells ◽  
Cell Reactivity ◽  
Tumor Immunosurveillance ◽  
Metastatic Burden ◽  
And Function

Abstract NK cells are lymphoid components of innate immunity and play an important role in tumor immunosurveillance. One of the major transcriptional regulators in lymphoid cells is NFAT (Nuclear Factor of Activated T Cells), as highlighted by its important role in T and B cell development and function. With regard to NK cells, available data indicate that NFAT is dispensable for development. However, several lines of evidence including the observation that the immunosuppressive drugs cyclosporin A and tacrolimus, which mediate their effects through inhibition of calcineurin and consecutively NFAT, influence NK reactivity implicate a role of this family of transcription factors in NK cell reactivity and function. Here we employed different genetic mouse models on the C57BL/6 background to directly study the functional role of NFAT in NK cells. We found that except for NFAT3 mRNA and protein of all family members (NFAT 1, 2, 4 and 5) was expressed in resting NK cells of wild type (WT) mice with NFAT1, 2 and 4 being most abundantly detectable. When we employed NK cells with knockout (KO) of NFAT 1, 2, and 4 in comparative in vitro analyses, we surprisingly found that lack of NFAT resulted in enhanced NK cell activation, degranulation and release of immunomodulatory cytokines like IFN-γ after co-culture with YAC-1 target cells as well as increased production of granzyme B and perforin after cytokine activation. The inhibitory effect of NFAT on NK cell effector function was further confirmed in vivo by employing WT and germ line NFAT KO animals in the syngeneic B16 melanoma model, which revealed a significantly reduced metastatic burden in NFAT KO mice. Depletion of NK cells in this model system in turn resulted in increased metastasis, however, with WT animals displaying significantly higher metastatic burden compared to NFAT KO mice. As this pointed to the fact that NFAT influences metastasis via both NK-dependent and independent mechanisms, we further generated mice with a NK cell-specific (conditional Ncr1-Cre dependent) NFAT2 KO. When these animals were employed again in analyses of B16 lung metastasis, comparative analyses with WT animals confirmed the inhibitory effect of NFAT on NK tumor immunosurveillance. Taken together, these results provide the first direct evidence for the functional involvement of NFAT in NK cell antitumor reactivity and, in contrast to T and B cells, identify NFAT as a negative regulator of NK cell function. Disclosures No relevant conflicts of interest to declare.

The Role of the PI3K-AKT-mTOR Pathway in NK Cell Anti-Tumor Reactivity.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3690-3690
Author(s):  
Matthias Krusch ◽  
Julia Salih ◽  
Ingrid Kumbier ◽  
Carolin Fenner ◽  
Lothar Kanz ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Nk Cells ◽  
Signaling Pathways ◽  
Nk Cell ◽  
Mtor Pathway ◽  
Target Cells ◽  
Cellular Cytotoxicity ◽  
Cell Functions ◽  
Ifn Γ

Abstract Abstract 3690 Poster Board III-626 The phosphatidylinositol 3-kinase – protein kinase B – mammalian target of rapamycin (PI3K – AKT – mTOR) pathway was found to be abnormally activated in many malignancies. Thus, protein kinase (PK) inhibitors (PKI) targeting different signaling molecules of this pathway are presently under clinical evaluation e.g. in sarcoma, multiple myeloma, or renal cell cancer. However, PK are also responsible for most of the signal transduction in immune effector cells and control various effector mechanisms including proliferation, cellular cytotoxicity, and cytokine release. Among those immunoregulatory signaling pathways, the PI3K – AKT – mTOR pathway was found to play a central role in TLR-mediated release of cytokines in macrophages and DC as well as in the regulation of T cell functions. Little is known about the role of this pathway in NK cell-mediated anti-tumor reactivity. Here we analyzed the tumor cell-induced activation of PI3K, AKT, and mTOR in NK cells and the consequences of an inhibition of these molecules by therapeutic PKI for NK cell anti-tumor reactivity. We found that, in response to tumor target cells, PI3K, AKT, and mTOR are consecutively activated in NK cells as revealed by western blot analyses using phospho-specific antibodies. Presence of the specific PI3K-inhbitor BKM-120 concentration-dependently inhibited cytotoxicity and IFN-g production of NK cells, which is in line with available data defining PI3K as a central regulator of NK cell target recognition. The mTOR inhibitors Sirolimus, Temsirolimus, and Everolimus did not alter cytotoxicity but significantly impaired NK cell IFN-γ production. In contrast, Triciribine, a compound which inhibits the phosphorylation and thus activation of AKT, did not influence cytotoxicity and, tantalizingly, even enhanced NK cell IFN-γ production. Thus, after target cell recognition and the activation of proximal PK like PI3K, different and at least partially independent signaling events govern NK cell cytokine production and cellular cytotoxicity. While the activity of PI3K followed by the activation of mitogen-activated PK is known to be crucial for NK cell cytotoxicity, we here identified the AKT – mTOR pathway as a yet unknown central component in the regulation of NK cell IFN-γ production. Moreover, in light of the important role of NK cells in tumor immune surveillance our data indicate that the choise and dosing of the most suitable PKI for a given cancer patient requires careful consideration. In the future it will be critical to define potential differences in immunosuppressive and immunostimulatory side effects of different compounds among the rapidly growing assortment of multi-targeted PKI to enable therapeutic approaches combining targeting of crucial signaling pathways in tumor cells with immunotherapy. Disclosures: No relevant conflicts of interest to declare.

Differential Effects of the BCR-ABL-Inhibitors Imatinib, Nilotinib and Dasatinib on NK Cell Reactivity against Chronic Myeloid Leukemia (CML)

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3200-3200
Author(s):  
Matthias Krusch ◽  
Julia Salih ◽  
Lothar Kanz ◽  
Helmut R Salih
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Minor Effect ◽  
Cell Cytotoxicity ◽  
Cell Reactivity ◽  
Erk Phosphorylation ◽  
Ifn Γ ◽  
Nk Cell Cytotoxicity ◽  
A Minor

Abstract CML is characterized by the BCR-ABL fusion protein, which mediates the oncogenic signaling. This led to the development of BCR-ABL inhibitors revolutionizing therapy of CML. However, as recently reported for Dasatinib (Schade et al., Blood 111:1366 (2008); Blake et al., Blood 111:4415 (2008)), these agents may impair the activity of immune effector cells like NK cells and T cells. After initiating oncogenic events, development and progression of clinically apparent malignancy is dependent on the evasion of the tumor cells from immunosurveillance. In light of the important role of NK cell reactivity against leukemia we compared the influence of Imatinib, Nilotinib and Dasatinib on the reactivity of both resting and IL-2 activated NK cells against CML cells to identify the compound with the least immuno-compromising side effects. First, the effects of the compounds on NK cell reactivity in concentrations corresponding to plasma peak levels were studied. Dasatinib (200nM) completely abolished NK cell granule mobilization, cytotoxicity and IFN-γ production, while no substantial inhibition was observed with Imatinib (5μM) and Nilotinib (3.6μM) mediated a minor but significant inhibition (p&lt;0.05, Student’s T-test). Presence of the compounds in concentrations corresponding to IC50 levels (Imatinib 600nM, Nilotinib 30nM, Dasatinib 10nM) revealed no influence of Imatinib and Nilotinib, while Dasatinib still significantly reduced NK cell cytotoxicity and IFN-γ production up to 60%. Since Dasatinib, in addition to BCR-ABL, potently inhibits SRC kinases, which are involved in the activation of MAPK pathways and thus crucial for NK cell cytotoxicity, we determined the influence of the compounds on ERK phosphorylation. While no inhibitory effect was observed using Imatinib and Nilotinib, Dasatinib markedly reduced ERK phosphorylation in NK cells. Our data demonstrate that NK cell anti-tumor reactivity is not inhibited by clinically relevant concentrations of Imatinib. While Nilotinib may mediate a minor effect, Dasatinib substantially impairs NK cell reactivity by inhibition of signaling pathways crucial for NK cell effector functions. For a given patient, the choice and dosing of the most suitable BCR-ABL inhibitor may thus require careful consideration of its influence on the immune system, especially in view of the important role of NK cells in the immunesurveillance of residual leukemia.

Consequences of 4-1BB-4-1BB Ligand Interaction for NK Cell Anti-Tumor Immunity: Opposite Effects of Seemingly Analogue Molecules in Mice and Men.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 279-279
Author(s):  
Tina Baessler ◽  
Jean E Charton ◽  
Corina Buechele ◽  
Benjamin J Schmiedel ◽  
Frank Gruenebach ◽  
...  
Keyword(s):  
Nk Cells ◽  
Tumor Immunity ◽  
Cytokine Production ◽  
Nk Cell ◽  
Leukemia Cells ◽  
Target Cells ◽  
Antibody Treatment ◽  
Cell Reactivity ◽  
Effector Functions ◽  
Human And Mouse

Abstract Abstract 279 In mouse models, stimulation of the TNF receptor family member 4-1BB/CD137 on cytotoxic lymphocytes by agonistic antibodies potently stimulated anti-tumor immunity, which has led to the development of humanized agonistic 4-1BB mAb that are presently being evaluated in clinical phase I/II studies (www.clinicaltrials.gov, keyword: CD137). However, seemingly analogue immunoregulatory molecules may mediate different effects in mice and men, and in humans yet nothing is known regarding the role of 4-1BB in NK cell reactivity. NK cells play an important role in tumor immunosurveillance, and largely contribute to the success of therapeutic strategies like (haploidentical) stem cell transplantation (SCT) or application of monoclonal antibodies like Rituximab by mediating graft versus leukemia activity and performing antibody-dependent cellular cytotoxicity (ADCC). Here we analyzed the expression of 4-1BB in human NK cells and compared the effect of 4-1BB signaling on effector functions of NK cells in mice and men. While being absent in resting state, both human and mouse NK cells acquire expression of 4-1BB at similar levels with comparable kinetics upon activation. Next we cultured human and mouse NK cells with target cells transfected with human and mouse 4-1BB ligand (4-1BBL) and analyzed the effect of 4-1BB on NK cell effector functions. 4-1BB – 4-1BBL interaction enhanced effector functions of mouse NK cells, while degranulation, cytotoxicity and cytokine production of human NK cells were substantially impaired (all p<0.01, Student's T-test). In line, employing primary leukemia cells from patients with AML (n= 65) and CLL (n=49), which were found to express 4-1BBL in 35% and 100%, respectively, we found that blocking 4-1BB-4-1BBL interaction markedly enhanced granule mobilization, cytotoxicity and interferon-g production of allogenic and autologous human NK cells in response to leukemia cells. In CLL, this inhibitory effect of 4-1BB-4-1BBL interaction on NK cell reactivity was observed both with regard to direct and Rituximab-induced cytotoxicity and cytokine production. Together, our data implicate that one should exercise caution in applying anti-4-1BB therapeutically, underline the necessity of detailed analyses regarding the function of seemingly analogue immunoregulatory molecules in mice compared to men and demonstrate that blocking 4-1BBL-4-1BB interaction may serve to enhance NK cell reactivity in therapeutic settings like allogenic SCT and antibody-treatment of malignancies in humans. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Expression Regulation and Function of T-Bet in NK Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Chen Huang ◽  
Jiacheng Bi
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Immune Surveillance ◽  
T Box ◽  
Effector Functions ◽  
Mtorc1 Signaling ◽  
Ifn Γ ◽  
And Function ◽  
Innate Lymphocytes

Natural killer (NK) cells are cytotoxic innate lymphocytes that play an important role in immune surveillance. The development, maturation and effector functions of NK cells are orchestrated by the T-box transcription factor T-bet, whose expression is induced by cytokines such as IFN-γ, IL-12, IL-15 and IL-21 through the respective cytokine receptors and downstream JAK/STATs or PI3K-AKT-mTORC1 signaling pathways. In this review, we aim to discuss the expression and regulation of T-bet in NK cells, the role of T-bet in mouse NK cell development, maturation, and function, as well as the role of T-bet in acute, chronic infection, inflammation, autoimmune diseases and tumors.

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