NK Cell Migration Research Articles

STYK1 mediates NK cell anti-tumor response through regulating CCR2 and trafficking

The serine/threonine/tyrosine kinase 1 (STYK1) is a receptor protein-tyrosine kinase (RPTK)-like molecule that is detected in several human organs. STYK1 plays an important role in promoting tumorigenesis and metastasis in various cancers. By analyzing the expression of RTKs in immune cells in the database of 2013 Immunological Genome Project, we found that STYK1 was principally expressed in NK cells. In order to investigate the function of STYK1, we used CRISPR/Cas9 technology to generate STYK1-deleted mice, we found STYK1 deletion mice have normal number, development, and function of NK cells in spleen and bone marrow in tumor-free resting state. To examine the tumor surveillance of STYK1 in vivo, we utilized a variety of tumor models, including NK cell-specific target cell (ß2M and RMA-S) clearance experiments in vivo, subcutaneous and intravenous injection of B16F10 melanoma model, and the spontaneous breast cancer model MMTV-PyMT. Surprisingly, we discovered that deletion of the oncogenic STYK1 promoted the four-model tumor progression, and we observed a reduction of NK cell accumulation in the tumor tissues of STYK1 deletion mice compared to WT mice. In order to study the mechanism of STYK1 in NK, RNA sequence of STYK1−/− and WT NK have unveiled a disparity in the signaling pathways linked to migration and adhesion in STYK1−/− NK cells. Further analysis of chemokine receptors associated with NK cell migration revealed that STYK1-deficient NK cells exhibited a significant reduction in CCR2 expression. The STYK1 expression was negatively associated with tumor progression in glioma patients. Overall, our study found the expression of STYK1 in NK cell mediates NK cell anti-tumor response through regulating CCR2 and infiltrating into tumor tissue.

The G Protein-Coupled Receptor GPR56 Is an Inhibitory Checkpoint for NK Cell Migration.

G protein-coupled receptors (GPCRs) represent the largest family of surface receptors and are responsible for key physiological functions, including cell growth, neurotransmission, hormone release, and cell migration. The GPCR 56 (GPR56), encoded by ADGRG1, is an adhesion GPCR found on diverse cell types, including neural progenitor cells, melanoma cells, and lymphocytes, such as effector memory T cells, γδ T cells, and NK cells. Using RNA-sequencing and high-resolution flow cytometry, we found that GPR56 mRNA and protein expression increased with NK cell differentiation, reaching its peak in adaptive NK cells. Small interfering RNA silencing of GPR56 led to increased spontaneous and chemokine-induced migration, suggesting that GPR56 functions as an upstream checkpoint for migration of highly differentiated NK cells. Increased NK cell migration could also be induced by agonistic stimulation of GPR56 leading to rapid internalization and deactivation of the receptor. Mechanistically, GPR56 ligation and downregulation were associated with transcriptional coactivator with PDZ-binding motif translocation to the nucleus and increased actin polymerization. Together, these data provide insights into the role of GPR56 in the migratory behavior of human NK cell subsets and may open possibilities to improve NK cell infiltration into cancer tissues by releasing a migratory checkpoint.

High-dimensional longitudinal immune profiling uncovers a dual role of the CXCL9/CXCR3, CXCL13/CXCR5, and CCL11/CCL3 axis in the coupling of immune-related adverse events to immune checkpoint inhibitor response.

2512 Background: Additional characterization is required to understand the immune network signatures and immunophenotypes that link immune-related adverse events (irAEs) to immune checkpoint inhibitor (ICI) therapy responses in cancer patients. Methods: A comprehensive immune profiling analysis was conducted on whole blood and peripheral blood mononuclear cells (PBMC) from 165 oncology patients with various irAEs, including colitis (n=64), myocarditis (n=19), pneumonitis (n=25), arthritis (n=24), and cytokine release syndrome CRS (n=33), and compared to a cohort of 219 cancer patients prior to ICI treatment. Results: Following ICI therapy on cycle 2 day 1 (C2D1), we observed significant increases in IL-6, CCL2, CXCL9, CXCL10, and CXCL13 levels preceding irAEs. CXCL9 was specifically upregulated during the development of colitis, arthritis, CRS, and myocarditis, while CXCL13 increased only in CRS, and CCL3 only in myocarditis and CRS, with no CCL11 upregulation in any irAE. High levels of CXCL9, high CCL11 and low CXCL13 strongly correlated with improved oncologic outcomes in different irAEs. Compared to other cluster, in the high CXCL9 cluster, 5-year overall survival (OS) was significantly improved (HR = 10.26 [95% CI, 1.27-82.82], p = 0.029) in colitis (n=20), in CRS (n=21) (HR = 6.45 [95% CI, 1.60-25.99], p = 0.009), and in arthritis. In the high CCL11 cluster, 5-year OS was significantly improved in pneumonitis (n=15), (HR = 4.04 [95% CI, 1.05-15.46]). Conversely, in myocarditis, the high CXCL13 cluster (n=9) was associated with decreased 2-year OS (HR = 6.05 [95% CI, 1.03-35.48], p = 0.046). It is important to note that the CXCL9-driven immunophenotypes were characterized by low IL-6. Notable observations include CD38 upregulation and large-scale activation of CD8 memory subsets during ICI therapy, concomitant with increased circulation of immature neutrophils at the onset of irAEs diagnosis. This event may increase the migration of TCRγδ, NK, DC, and CD8 cells to tumor sites through CXCR3/CXCL9 interactions. Conclusions: This study unravels intricate connections between immune activation and tumor response. CXCL9, CCL11, and CXCL13 emerge as pivotal biomarkers bridging the gap between ICI therapy effectiveness and distinct irAEs-associated immunophenotypes.

The therapeutic potential of RANTES/CCL5 across diverse infections and its synergistic enhancement by ezrin peptide RepG3 for long COVID

The amplification of anti-infective immunity against a wide spectrum of acute and chronic infections caused by various pathogens is mediated by RANTES/CCL5. This chemokine controls infections caused by viruses, bacteria, fungi, and protozoans. In addition, RANTES/CCL5 exhibits anti-cancer effects by increasing NK-cell activity and targeting tumors. RANTES/CCL5 acts by amplifying antigen-specific immunity on mucosal surfaces, programmed T-cell responses, cytotoxic T lymphocytes (CTL), B-cell activation, and antibody production. RANTES/CCL5 exerts its effects by binding to C-C receptors, thereby triggering JAK/STAT signaling and inducing the migration of lymphocytes, NK cells, and monocytes. In the brain, RANTES/CCL5 activates astrocytes and upregulates anti-inflammatory interleukin (IL)-10 expression. Inflammatory cytokines rapidly induce RANTES/CCL5 expression in fibroblasts, epithelial cells, and monocytes/macrophages. In T-cells, RANTES/CCL5 expression is mediated by translational control of the transcription factor RFLAT-1/KLF13, which is responsible for a 3-day delay in RANTES/CCL5 secretion after T-cell activation. A cell membrane multi-protein complex containing CFTR, EBP50, ezrin, and PKC is a dominant regulator of both RANTES/CCL5 and inflammatory cytokine expression. Treatment of a volunteer patient suffering from long COVID/vaccine injury with the ezrin peptide RepG3 alleviated symptoms, substantially reduced serum proinflammatory cytokines to normal levels, and enhanced the expression of RANTES/CCL5. The immune amplification activities of RANTES/CCL5 and the ezrin peptide RepG3 exhibit striking similarities. In contrast, the ezrin peptide RepG3 differs from RANTES/CCL5 in its ability to significantly inhibit the expression of proinflammatory cytokines IL-1β, IL-6, IL-8, IL-13, TNF-α, and proinflammatory chemokines MIP-1α and MIP-1β. The mechanism through which the ezrin peptide RepG3 enhances adaptive immunity likely involves its induction of systemic elevation of RANTES/CCL5 expression and the simultaneous inhibition of proinflammatory cytokine expression.

Crosstalk between NFAT and NFκB Signaling Regulates NK Cell Immunosurveillance

One of the major transcriptional regulators in lymphoid cells is NFAT (Nuclear Factor of Activated T Cells), controlling lymphocyte development and activity. The role of NFAT signaling is well defined in T cells, the cytotoxic lymphocytes of the adaptive immunity. However, surprisingly little is known regarding the relevance of this transcription factor family in NK cells as effector cells of the innate immunity. Available data indicate that NFAT activity is dispensable for development of NK cells, whereas effects of the immunosuppressive drugs cyclosporin A and tacrolimus, that inhibit calcineurin and consecutively NFAT, implicate an involvement of the NFAT family in NK cell function. We here employed different genetic mouse models and functional analyses to unravel the role of NFAT1 (NFATc2) and NFAT2 (NFATc1) in NK cell reactivity. In vitro knockout (KO) of NFAT1 (NFATc2) or NFAT2 (NFATc1) enhanced NK cell degranulation and resulted in increased production of granzyme B and perforin upon stimulation of activating receptors like NK1.1 or Nkp46 or upon co-culture with different leukemia and solid tumor cells. In line, cytotoxicity assays revealed increased lysis of YAC-1 and B16F10 tumor cells by both NFAT1- and NFAT2-deficient NK cells as compared to wildtype (WT) controls. The inhibitory effect of NFAT transcription factors on NK cell effector function could also be confirmed in vivo by employing WT and NFAT KO animals in syngeneic B16F10 melanoma, RMA-S lymphoma and LL/2-luc lung carcinoma models, which revealed a significantly reduced tumor burden in NFAT1 and NFAT2 KO mice. Furthermore, we detected higher numbers of tumor infiltrating NK cells in NFAT KO mice, which suggested improved NK cell migration and homing to the tumor side. Comparative analyses with single NFAT as well as NFAT1+NFAT2 double KO and WT animals further confirmed the inhibitory effect of NFAT1 and NFAT2 and pointed to additive effects of NFAT1 and NFAT2 in NK cell tumor immunosurveillance. Proteomics analysis of NK cells from the different NFAT KO strains revealed altered expression of molecules which are regulating chemokine receptor expression as well as a decreased expression of NFκB inhibitory molecules, like NFKBIB (NFKB inhibitor beta) Commd6 (COMM domain containing 6). NFκB signaling was shown to regulate granzyme B and perforin synthesis and expression. Thus, we suggest that NFAT1 and NFAT2 inhibit NFκB signaling in NK cells, and NFAT1 and NFAT2 KO reinforce NFκB induced granzyme B and perforin expression and thereby increase NK cell cytotoxicity. Taken together, our results identify NFAT as a negative regulator of NK cell function. In addition, we provide the first evidence for a direct functional involvement of NFAT1 and NFAT2 in NK cell antitumor reactivity by regulation tumor infiltration and cytotoxicity of NK cell.

CCR5 drives NK cell-associated airway damage in pulmonary ischemia-reperfusion injury.

Primary graft dysfunction (PGD) limits clinical benefit after lung transplantation, a life-prolonging therapy for patients with end-stage disease. PGD is the clinical syndrome resulting from pulmonary ischemia-reperfusion injury (IRI), driven by innate immune inflammation. We recently demonstrated a key role for NK cells in the airways of mouse models and human tissue samples of IRI. Here, we used 2 mouse models paired with human lung transplant samples to investigate the mechanisms whereby NK cells migrate to the airways to mediate lung injury. We demonstrate that chemokine receptor ligand transcripts and proteins are increased in mouse and human disease. CCR5 ligand transcripts were correlated with NK cell gene signatures independently of NK cell CCR5 ligand secretion. NK cells expressing CCR5 were increased in the lung and airways during IRI and had increased markers of tissue residency and maturation. Allosteric CCR5 drug blockade reduced the migration of NK cells to the site of injury. CCR5 blockade also blunted quantitative measures of experimental IRI. Additionally, in human lung transplant bronchoalveolar lavage samples, we found that CCR5 ligand was associated with increased patient morbidity and that the CCR5 receptor was increased in expression on human NK cells following PGD. These data support a potential mechanism for NK cell migration during lung injury and identify a plausible preventative treatment for PGD.

Regulation of NK cell chemotaxis by KCa3.1 channels

Abstract CD8+ T cells and NK cells are the primary line of defense against tumor cells. However, the tumor microenvironment impairs their anti-tumor capabilities. One of the key functions impaired is the ability of T and NK cells to infiltrate the tumor, essential to allow the direct contact with a target cell and its killing. Kv1.3 and KCa3.1 K +channels have a multitude of essential functions that have been established in CD8+ T cells: Kv1.3 regulates cytotoxicity and KCa3.1 chemotaxis. However, less is known about K +channels in NK cells. Herein, we performed electrophysiological and 3D chemotaxis experiments to study the activity and functional role of K +channels in human NK cells. NK cells were isolated from healthy donors (HD) and head and neck cancer (HNC) patients and activated with IL-2 and IL-15 for 24–48 hr. Activation led to an increase in Kv1.3 currents of 49.6% at 24 hr and 434.1% at 48 hr . KCa3.1 activity increased by 42.8% at 24 hr and 54.2% at 48 hr. Chemotaxis experiment showed that activated NK cells move randomly in the collagen matrix and migrated towards the chemokine gradient in presence of CXCL10. Chemotaxis, but not random migration, was inhibited by the selective KCa3.1 blocker TRAM-34 in NK cells from HD and HNC patients. Shk-Dap22, a Kv1.3 blocker, did not alter either chemotaxis or random migration. Overall, TRAM-34 reduced the distance achieved by NK cells in the chemokine gradient by 157% in HD (4 donors) and 89% in HNC NK cells (1 donor). These data highlight the critical role of KCa3.1 channels in NK cell migration and open the possibility of targeting KCa3.1 to facilitate tumor infiltration by NK cells.

The co-inhibitory receptor TIGIT regulates NK cell function and is upregulated in human intrahepatic CD56bright NK cells.

The crosstalk between NK cells and their surrounding environment is enabled through activating and inhibitory receptors, which tightly control NK cell activity. The co-inhibitory receptor TIGIT decreases NK cell cytotoxicity and is involved in NK cell exhaustion, but has also been associated with liver regeneration, highlighting that the contribution of human intrahepatic CD56bright NK cells in regulating tissue homeostasis remains incompletely understood. A targeted single-cell mRNA analysis revealed distinct transcriptional differences between matched human peripheral blood and intrahepatic CD56bright NK cells. Multiparameter flow cytometry identified a cluster of intrahepatic NK cells with overlapping high expression of CD56, CD69, CXCR6, TIGIT and CD96. Intrahepatic CD56bright NK cells also expressed significantly higher protein surface levels of TIGIT, and significantly lower levels of DNAM-1 compared to matched peripheral blood CD56bright NK cells. TIGIT+ CD56bright NK cells showed diminished degranulation and TNF-α production following stimulation. Co-incubation of peripheral blood CD56bright NK cells with human hepatoma cells or primary human hepatocyte organoids resulted in migration of NK cells into hepatocyte organoids and upregulation of TIGIT and downregulation of DNAM-1 expression, in line with the phenotype of intrahepatic CD56bright NK cells. Intrahepatic CD56bright NK cells represent a transcriptionally, phenotypically, and functionally distinct population of NK cells that expresses higher levels of TIGIT and lower levels of DNAM-1 than matched peripheral blood CD56bright NK cells. Increased expression of inhibitory receptors by NK cells within the liver environment can contribute to tissue homeostasis and reduction of liver inflammation.

Brain endothelial CXCL12 attracts protective natural killer cells during ischemic stroke

BackgroundThe innate lymphoid cell (ILC) family consists of NK cells, ILC type 1, 2, 3 and lymphoid tissue inducer cells. They have been shown to play important roles in homeostasis and immune responses and are generally considered tissue resident. Not much is known about the presence of ILC members within the central nervous system and whether they are tissue resident in this organ too. Therefore, we studied the presence of all ILC members within the central nervous system and after ischemic brain insult.MethodsWe used the photothrombotic ischemic lesion method to induce ischemic lesions within the mouse brain. Using whole-mount immunofluorescence imaging, we established that the ILCs were present at the rim of the lesion. We quantified the increase of all ILC members at different time-points after the ischemic lesion induction by flow cytometry. Their migration route via chemokine CXCL12 was studied by using different genetic mouse models, in which we induced deletion of Cxcl12 within the blood–brain barrier endothelium, or its receptor, Cxcr4, in the ILCs. The functional role of the ILCs was subsequently established using the beam-walk sensorimotor test.ResultsHere, we report that ILCs are not resident within the mouse brain parenchyma during steady-state conditions, but are attracted towards the ischemic stroke. Specifically, we identify NK cells, ILC1s, ILC2s and ILC3s within the lesion, the highest influx being observed for NK cells and ILC1s. We further show that CXCL12 expressed at the blood–brain barrier is essential for NK cells and NKp46+ ILC3s to migrate toward the lesion. Complementary, Cxcr4-deficiency in NK cells prevents NK cells from entering the infarct area. Lack of NK cell migration results in a higher neurological deficit in the beam-walk sensorimotor test.ConclusionsThis study establishes the lack of ILCs in the mouse central nervous system at steady-state and their migration towards an ischemic brain lesion. Our data show a role for blood–brain barrier-derived CXCL12 in attracting protective NK cells to ischemic brain lesions and identifies a new CXCL12/CXCR4-mediated component of the innate immune response to stroke.

Effect of azithromycin on migration of peripheral blood NK cells from patients with chronic obstructive pulmonary disease

Currently, no drugs have been identified that could slow progression of chronic obstructive pulmonary disease (COPD), or have a significant impact on patient mortality. Therefore, research continues aimed at studying the mechanisms of COPD development and searching for drugs that affect its molecular pathogenesis. The aim of our work was to determine the ability of azithromycin combined with corticosteroids to affect the migration of peripheral blood NK cells from the COPD patients. In the present study, we have measured expression of chemokine receptors CCR5, CCR6, CCR7, CXCR3, CXCR4, CXCR6 on the surface of peripheral blood NK cells (CD3- CD56+) by means of flow cytometry in 54 smoking patients with COPD, 21 healthy smokers, and 20 healthy non-smokers. Moreover, the effect of azithromycin (10 µg/mL) and budesonide (10 nM) on the migration of NK cells from COPD patients (n = 8) towards CCL5 (10 nM) and CXCL10 (10 nM) was determined. We found that the percentage of NK cells expressing CXCR3 and CCR5 chemokine receptors was increased in smoking patients with COPD compared with healthy smokers and healthy non-smokers. However, the proportion of these NK cell subsets did not differ between healthy smokers and healthy non-smokers. There were no significant differences in the percentage of NK cells expressing CXCR4, CXCR6, CCR6, CCR7 chemokine receptors between the three groups of subjects. Addition of budesonide to the cell suspensions decreased the migration of blood NK cells towards CCL5 and CXCL10. Azithromycin was also shown to suppress the migration of blood NK cells towards these chemokines. The combination of azithromycin and budesonide was more potent at inhibiting NK cell chemotaxis towards CCL5 and CXCL10 than any of these drugs added alone. Our results demonstrate a change in the chemokine receptor profile of NK cells in COPD patients and indicate the advantages of the combined use of corticosteroids and azithromycin for COPD treatment.

Peritoneal natural killer cell chemotaxis is decreased in women with pelvic endometriosis.

NK cell and macrophage function are decreased in endometriosis, and the disease may involve reduced immune surveillance in the peritoneal cavity. NK cell cytotoxicity and migration ability (chemotaxis) are considered important; the former has been investigated, but the latter has not. We compared chemotaxis of immunocompetent cells (NK cells, macrophages, T cells) in peritoneal fluid obtained during laparoscopy in 27 women with and 13 without endometriosis. Peripheral blood NK cells were also obtained by the peripheral blood antibody beads method. Micro-cultured cells were examined by time-lapse photography, and the mean migration speed per cell was calculated as the chemotaxis. We investigated the relationship between chemotaxis and endometriosis. NK cell chemotaxis was significantly lower in the endometriosis group. Macrophages and lymphocytes were not significantly different between the groups. During menstruation, NK cell chemotaxis decreased in both groups. Postmenstrual chemotaxis was increased significantly in women without endometriosis but remained low in women with endometriosis. The Revised-American Society for Reproductive Medicine score was not correlated with chemotaxis; in women with endometriosis, chemotaxis was decreased even at early stages. Peripheral blood NK cells showed no significant differences. In women with endometriosis, not only cytotoxicity but also chemotaxis by NK cells in peritoneal cavity is significantly decreased, and particularly chemotaxis is decreased throughout the menstrual cycle. Therefore, antigens in retrograde menstrual blood that enters the peritoneal cavity might be left unprocessed. Repetition of this immune process in the peritoneal cavity may lead to the onset and subsequent progression of endometriosis.

In Situ Activated NK Cell as Bio‐Orthogonal Targeted Live‐Cell Nanocarrier Augmented Solid Tumor Immunotherapy

AbstractNatural killer (NK) cell‐based immunotherapy holds prominent potential for cancer treatment. However, its application in solid tumors is limited by a rapid decline in viability and function, as well as inadequate homing and infiltration. Herein, a generalized strategy is offered to construct a bio‐orthogonal targeted live‐cell nanocarrier (N3‐NK‐NPs) by coupling with responsive released interleukin‐21 (IL‐21) nanoparticles (ILNPs) on glyco‐engineered NK cell surfaces. Complementary bio‐orthogonal groups (azide (N3)/bicyclo [6.1.0] nonyne (BCN), serving as an artificial ligand receptor are separately implanted into NK cells (N3‐NK) and tumor cells (BCN‐Raji) via nondestructive metabolic glycoengineering. The bio‐orthogonal strategy effectively promotes the specific recognition and migration of NK cells, showing nearly fourfold deeper infiltration in tumor than control groups. Compared with traditional systemic administration, ILNPs hitchhiking on cell vectors selectively in situ releases the IL‐21 adjuvant in the tumor to produce effective and continuous “pseudo‐autocrine” stimulation surrounding NK cells under a low dose (5 µg kg–1), which greatly promotes proliferation and activation of NK cells, resulting in enhanced therapeutic potential while limiting systemic toxicity. Importantly, live‐cell nanocarrier effectively activates innate immune system through IL‐21 triggered recruitment of multiple immunocytes, significantly improving tumor immune microenvironment. This in situ activated NK cell nanocarrier with bio‐orthogonal targeting provides a universal and powerful strategy for immune cells activation and solid tumor immunotherapy.

Low Dose Cyclophosphamide in Combination with Elotuzumab - a Novel Immunotherapeutic Strategy for Multiple Myeloma

IntroductionCyclophosphamide (CTX) is a widely used anti-neoplastic, performing as an alkylating agent at high doses and immunomodulatory agent at low doses 1.. Combining CTX with monoclonal antibody (mAb) therapy has proven beneficial in potentiating relapsed and/or refractory multiple myeloma (RRMM) therapies, with daratumumab-directed MM cell death enhanced in the presence of CTX 2,3.. Elotuzumab (ELO), the second mAb approved for treating RRMM, promotes MM cell clearance by enhancing macrophage-mediated phagocytosis and CD16- and SLAMF7-directed NK cell cytotoxicity. ELO has been approved for use alongside dexamethasone and lenalidomide 4 or pomalidomide (POM) 5.. However, potential therapeutic benefits of ELO in combination with immunomodulatory drugs such as CTX and POM have yet to be examined. Our research investigates, the efficacy of combining low-dose CTX, alone or in combination with POM, and ELO in enhancing macrophage and NK cell infiltration and function in the MM tumour microenvironment.Materials and MethodsMultiple myeloma cells (MM1S and H929) were treated with low-dose CTX and/or POM for 24hrs, washed to remove residual drug and resuspended in fresh media for tumour cell secretome (TCS) generation. Direct effects of CTX and/or POM on surface expression of checkpoint proteins (PD-1 and CD47) on MM cells was assessed by mean fluorescent intensity (MFI) flow cytometry. CD32/CD64 receptor expression on THP-1 macrophages, NKG2D, CD2, DNAM-1, CD96 and KIR2DL1 receptors on KHYG1 and primary NK cells, were measured using flow cytometry as a measure of activation. Migration of serum-starved, CFSE-labelled macrophages and NK cells towards CTX and/or POM TCS was assessed after 4hrs, with total number of migrated cells quantified using the Accuri flow cytometer. Immune cell function following indirect conditioning of macrophages/NK cells with MM cell TCS was measured by quantifying antibody-directed cellular phagocytosis (ADCP) or antibody-directed cellular cytotoxicity (ADCC), respectively. Conditioned immune cells were co-cultured with MM cells in a 2:1 effector to target ratio for 4hrs in the absence/presence of mAbs (ELO, nivolumab and anti-CD47), after which MM cell clearance was quantified by flow cytometry and presented as relative uptake (ADCP) and cytotoxicity (ADCC). One-way ANOVA statistical analysis was performed, followed by Tukey post hoc tests, with significance recognized at p<0.05.ResultsDirect treatment of MM cells with CTX increased surface expression of immune evading checkpoint proteins PD-1 and CD47 (p<0.05,n=3). POM monotherapy did not alter PD-1/CD47 expression, however dual therapy of CTX and POM supported the CTX-driven effect (p<0.001,n=3). Expression of CD32/CD64 macrophage activation markers was significantly increased on THP-1 cells following CTX-TCS conditioning (p<0.001,n=3). POM altered CD32, but not CD64, however dual treatment with CTX and POM significantly increased expression of both CD32 and CD64 (p<0.001, n=3). Migration of macrophages towards CTX-TCS was enhanced in a dose-dependent manner (p<0.01,n=3). CTX and POM dual therapy supported this CTX driven effect (p<0.001,n=3). Migration trends of both primary and KHYG1 NK cells were also increased towards the secretome from CTX treated MM cells. ADCP and ADCC were increased by CTX alone or in combination with POM (p<0.05, n=3). Effects of CTX on ADCP were not significantly enhanced by ELO, however ELO did significantly augment ADCC by CTX-conditioned primary NK cells (p<0.05,n=3). Given the increased expression of PD-1 and CD47, we investigated if the inclusion of nivolumab and anti-CD47 mAbs potentiated ADCC. Although ADCC was increased in all combinations, there was no significant difference between ELO alone versus ELO in combination with either nivolumab or anti-CD47.ConclusionsLow-dose CTX and POM potentiated the immunomodulatory effects of ELO, with NK-directed cytotoxicity of MM cells enhanced in the presence of this mAb. Our data therefore indicates that the inclusion of low-dose CTX and or POM in combination with ELO could be a novel immunotherapeutic strategy for treating RRMM.

The Biological Role and Therapeutic Potential of NK Cells in Hematological and Solid Tumors.

NK cells are an attractive target for cancer immunotherapy due to their potent antitumor activity. The main advantage of using NK cells as cytotoxic effectors over T cells is a reduced risk of graft versus host disease. At present, several variants of NK-cell-based therapies are undergoing clinical trials and show considerable effectiveness for hematological tumors. In these types of cancers, the immune cells themselves often undergo malignant transformation, which determines the features of the disease. In contrast, the current use of NK cells as therapeutic agents for the treatment of solid tumors is much less promising. Most studies are at the stage of preclinical investigation, but few progress to clinical trials. Low efficiency of NK cell migration and functional activity in the tumor environment are currently considered the major barriers to NK cell anti-tumor therapies. Various therapeutic combinations, genetic engineering methods, alternative sources for obtaining NK cells, and other techniques are aiming at the development of promising NK cell anticancer therapies, regardless of tumorigenesis. In this review, we compare the role of NK cells in the pathogenesis of hematological and solid tumors and discuss current prospects of NK-cell-based therapy for hematological and solid tumors.

Natural killer cell immunosuppressive function requires CXCR3-dependent redistribution within lymphoid tissues.

NK cell suppression of T cells is a key determinant of viral pathogenesis and vaccine efficacy. This process involves perforin-dependent elimination of activated CD4+ T cells during the first 3 days of infection. Although this mechanism requires cell-cell contact, NK cells and T cells typically reside in different compartments of lymphoid tissues at steady state. Here, we showed that NK cell suppression of T cells is associated with transient accumulation of NK cells within T cell-rich sites of the spleen during lymphocytic choriomeningitis virus infection. The chemokine receptor CXCR3 was required for this relocation and suppression of antiviral T cells. Accordingly, NK cell migration was mediated by type I IFN-dependent promotion of CXCR3 ligand expression. In contrast, adenoviral vectors that weakly induced type I IFN and did not stimulate NK cell inhibition of T cells also did not promote measurable redistribution of NK cells to T cell zones. Exogenous IFN rescued NK cell migration during adenoviral vector immunization. Thus, type I IFN and CXCR3 were critical for properly positioning NK cells to constrain antiviral T cell responses. Development of strategies to curtail migration of NK cells between lymphoid compartments may enhance vaccine-elicited immune responses.

NK-B cell cross talk induces CXCR5 expression on natural killer cells

SummaryB cell follicles (BCFs) in lymph nodes (LNs) are generally exempt of CD8+ T and NK cells. African green monkeys (AGMs), a natural host of simian immunodeficiency virus (SIV), display NK cell-mediated viral control in BCF. NK cell migration into BCF in chronically SIVagm-infected AGM is associated with CXCR5+ NK cells. We aimed to identify the mechanism leading to CXCR5 expression on NK cells. We show that CXCR5+ NK cells in LN were induced following SIVagm infection. CXCR5+ NK cells accumulated preferentially in BCF with proliferating B cells. Autologous NK-B cell co-cultures in transwell chambers induced CXCR5+ NK cells. Transcriptome analysis of CXCR5+ NK cells revealed expression of bcl6 and IL6R. IL-6 induced CXCR5 on AGM and human NK cells. IL6 mRNA was detected in LN at higher levels during SIVagm than SIVmac infection and often produced by plasma cells. Our study reveals a mechanism of B cell-dependent NK cell regulation.

Fractalkine Elicits Chemotactic, Phenotypic, and Functional Effects on CX3CR1+CD27- NK Cells in Obesity-Associated Cancer.

Esophagogastric adenocarcinomas (EAC) are obesity-associated malignancies underpinned by severe immune dysregulation and inflammation. Our previous work indicates that NK cells migrate to EAC omentum, where they undergo phenotypic and functional alterations and apoptosis. In this study, we investigate whether such erroneous chemotaxis to omentum is paralleled by compromised NK cell infiltration of EAC patient tumor and examine the role of the inflammatory chemokine fractalkine in shaping the NK cell-mediated response. Our data show diminished NK cell frequencies in EAC tumor compared with those in the circulation and reveal that intratumoral NK cell frequencies decline as visceral obesity increases in EAC patients. Our in vitro findings demonstrate that antagonism of fractalkine receptor CX3CR1 significantly reduces NK cell migration to EAC patient-derived, omental adipose tissue-conditioned media, but not toward tumor-conditioned media. These data suggest fractalkine is a key driver of NK cell chemotaxis to omentum but has a lesser role in NK cell homing to tumor in EAC. We propose that this may offer a novel therapeutic strategy to limit NK cell depletion in the omentum of obese EAC patients, and our data suggest the optimal timing for CX3CR1 antagonism is after neoadjuvant chemoradiotherapy. Our functional studies demonstrate that fractalkine induces the conversion from CX3CR1+CD27- to CX3CR1-CD27+ NK cells and increases their IFN-γ and TNF-α production, indicative of its role in shaping the dominant NK cell phenotype in EAC omentum. This study uncovers crucial and potentially druggable pathways underpinning NK cell dysfunction in obesity-associated cancer and provides compelling insights into fractalkine's diverse biological functions.

Abstract 2676: GSK3β inhibition by small molecule 9-ING-41 decreases VEGF and other cytokines, and boosts NK and T cell-mediated killing of colorectal tumor cells

Abstract The GSK3β/beta-catenin axis activates vascular endothelial growth factor (VEGF) signaling in endothelial cells to promote angiogenesis. VEGF has been noted as immunosuppressive, it dampens the immune cell response by promoting recruitment of tumor associated macrophages (TAMs), and has been proposed as a target to modulate antitumor immunity. A panel of human colorectal cell lines was chosen to provide a varied mutational background (TP53, KRAS, BRAF, TRK, APC, PIK3CA). Cells were treated with 9-ING-41, a selective and potent small molecule inhibitor of GSK3β, at doses up to 50 µM for 72 hours to determine IC10, IC30, IC50, and IC70. Cytokine, chemokine, and growth factor levels were analyzed in the tumor cell culture supernatants after treatment at IC10, IC30, IC50, and IC70 for 48 hours using a Luminex 200 multiplexing instrument. Co-culture experiments were conducted with GFP+ SW480 colorectal cancer cells and either NK-92 natural killer cells or TALL-104 T cells at various effector/target ratios in a 48-well plate, in the presence or absence of 9-ING-41. Overall cytokine levels showed a decreasing trend in response to increasing doses of 9-ING-41. Among the most prominently decreased growth factors in the profile was VEGF. In an immune cell-killing co-culture assay we observed a significant increase in natural killer (NK-92) cell and T cell (TALL-104) killing of the colorectal cancer cells in response to treatment with 9-ING-41 as compared to controls without drug treatment. Follow-up experiments compared the effect of pre-treating either the effector or the target cell population with 9-ING-41 before the co-culture experiment was started. Pre-treatment of the target tumor cells, but not the effector immune cells, bolstered cell-killing, implying that the drug is sensitizing the tumor cells to killing by the immune cells. Moreover, we saw an increase in the expression of chemokine CXCL14 (BRAK) in the tumor cell culture supernatant with increasing doses of 9-ING-41. BRAK is known to stimulate activated NK cell migration and could have a beneficial therapeutic effect by increasing NK cell migration into the tumor microenvironment. Furthermore, we saw a decrease in macrophage colony-stimulating factor (M-CSF) which, along with VEGF, has been associated with recruitment of TAMs. We hypothesize that a 9-ING-41-mediated decrease of VEGF in conjunction with a 9-ING-41-mediated increase of BRAK secreted by the tumor cells may increase the capacity of NK- and T cell-mediated killing of the tumor cells. Utilizing a compound such as 9-ING-41 could be a way to increase the host's anti-tumor immune response to decrease tumor burden in conjunction with other therapeutic agents. Citation Format: Kelsey E. Huntington, Shengliang Zhang, Benedito A. Carneiro, Wafik S. El-Deiry. GSK3β inhibition by small molecule 9-ING-41 decreases VEGF and other cytokines, and boosts NK and T cell-mediated killing of colorectal tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2676.

CDX2 enhances natural killer cell-mediated immunotherapy against head and neck squamous cell carcinoma through up-regulating CXCL14.

(NK) cells are at the first line of defence against tumours, but their anti‐tumour mechanisms are not fully understood. We aimed to investigate the mechanism by which NK cells can mediate immunotherapy against head and neck squamous cell carcinoma (HNSCC). We collected fifty‐two pairs of HNSCC tissues and corresponding adjacent normal tissues; analysis by RT‐qPCR showed underexpression of CXCL14 in HNSCC tissues. Primary NK cells were then isolated from the peripheral blood of HNSCC patients and healthy donors. CXCL14 was found to be consistently under‐expressed in the primary NK cells from the HNSCC patients. However, CXCL14 expression was increased in IL2‐activated primary NK cells and NK‐92 cells. We next evaluated NK cell migration, IFN‐γ and TNF‐α expression, cytotoxicity and infiltration in response to CXCL14 overexpression or knockdown using gain‐ and loss‐of‐function approach. The results exhibited that CXCL14 overexpression promoted NK cell migration, cytotoxicity and infiltration. Subsequent in vivo experiments revealed that CXCL14 suppressed the growth of HNSCC cells via activation of NK cells. ChIP was applied to study the enrichment of H3K27ac, p300, H3K4me1 and CDX2 in the enhancer region of CXCL14, which showed that CDX2/p300 activated the enhancer of CXCL14 to up‐regulate its expression. Rescue experiments demonstrated that CDX2 stimulated NK cell migration, cytotoxicity and infiltration through up‐regulating CXCL14. In vivo data further revealed that CDX2 suppressed tumorigenicity of HNSCC cells through enhancement of CXCL14. To conclude, CDX2 promotes CXCL14 expression by activating its enhancer, which promotes NK cell–mediated immunotherapy against HNSCC.

Effects of Regulating Smad7 Gene on Epithelial-Mesenchymal Transition in Keloid Keratinocyte

The effect of Smad7 on epithelial-Mesenchymal Transition (EMT) of keloid keratinocytes was studied. Culture formed keloid cutin cells (KK) and normal skin cutin cell (NK cells), built the Smad7 too slow virus slow virus vector and Smad7 interference expression vector, screening the best expression and interfering with the slow virus infection NK and KK cells respectively, and contrast carrier puro screening stable expression cell lines, stem cells can be divided into 8 groups: NK-Control (normal training of NK cells); NK-NC (NK cells screened against lentivirus); NK-shSmad7 (NK cells that interfere with lentivirus screening); NK-mSmad7 (NK cells screened for overexpression of lentivirus); KK-control (normal cultured KK cells); KK-NC (KK cells screened against lentivirus); KK-shSmad7 (KK cells that interfere with lentivirus screening); KK-mSmad7 (KK cells screened for overexpression of lentivirus). Cell proliferation was observed by the CCK-8 method, cell apoptosis was detected by flow cytometry, cell migration ability was detected by Transwell chamber, and expression of key proteins (N-cadherin and Occludin) in epithelium-interstitial transform was detected by Western blot. The Smad7 interfering lentivirus vector and Smad7 overexpressing lentivirus vector were successfully constructed. Interference with Smad7 can promote NK cell and KK cell proliferation and migration, and inhibit KK cell apoptosis, but it has no significant effect on NK cell apoptosis ( P>0.05). Overexpression of Smad7 inhibited the proliferation and migration of NK cells and KK cells, and promoted their apoptosis. After interfering with lentivirus infection, NK cells and KK cells showed decreased expression of Occludin protein compared with NC group ( P<0.01), increased N-cadherin protein expression in KK cells ( P<0.01), but there was no significant change in N-cadherin protein expression in NK cells ( P>0.05); After lentivirus overexpression, NK and KK cells showed increased expression of Occludin protein ( P<0.05), the expression of N-cadherin protein in NK cells decreased ( P<0.05), but there was no significant change in N-cadherin protein expression in KK cells ( P>0.05). The regulation of Smad7 gene can affect the EMT in normal skin keratinocytes and keloid keratinocytes, and further regulate the ability of cell proliferation, migration and apoptosis. The effect of Smad7 gene regulation on EMT in keloid keratinocytes was greater than that on normal skin keratinocytes.