Killing Activity Of NK Cells Research Articles

Abstract A021: Nutrient competition in the tumor microenvironment alters NK cell metabolism in Pancreatic Cancer

Abstract Tumor cells present constant nutritional demand of macronutrients and micronutrients for their rapid growth needs. Often this nutrient limitation hampers the function of anti-tumor immune cells, which need basal energy levels to execute cytotoxic effects against malignant cells. Hence, we investigated nutrient limitation-induced metabolic alterations in NK cells that regulate the anti-tumor activity of NK cells. Using 2D cultures and PDAC organoid models, we demonstrate that pancreatic tumor cells exhaust vitamin B6 (VB6) in the co-culture milieu, causing reduced killing activity of NK cells. Additionally, we demonstrate that PDAC patients have significantly reduced plasma VB6 as compared to the healthy counterparts. This data aligns with the epidemiological studies showing that VB6 intake reduces the risk of pancreatic cancer incidence. Moreover, we noted a significant reduction in circulating VB6 in the pancreatic tumor-bearing mice as compared to healthy counterparts. Utilizing mass spectrometry-based metabolomics we noted that limitation of the VB6 prevents glycogen breakdown in NK cells. This was validated by follow up electron microscopy-based studies that demonstrated glycogen depots in NK cells that were very prominent upon inhibiting glycogenolysis. Metabolic tracing studies demonstrated that NK cells require VB6 for intracellular glycogen breakdown. Correspondingly, knocking down glycogen phosphorylase, a key enzyme involved in glycogen breakdown abrogated anti-tumoral NK cell function. Notably, supplementation of co-cultures in 2D and organoid models and in vivo orthotopic mouse models, with VB6 restored NK cell function against pancreatic tumor cells. In parallel, we observed dependence of tumor cell metabolism on VB6 for sustaining growth. Accordingly, we observed that tumor cells actively deplete VB6 in tumor microenvironments, as observed by comparing VB6 levels in circulation and in tumor interstitial fluids. Finally, we observed that VB6 supplementation in combination with inhibitors targeting VB6-driven metabolic pathway dependencies in tumor cells effectively enhances NK cell frequency and diminishes tumor burden in vivo. These studies demonstrate a novel role of glycogen breakdown as a critical energy source for activated NK cells and demonstrate, for the first time a key role of glycogenolysis in NK cell cytotoxic activities. Our results expand the understanding of the critical role of micronutrients (vitamin B6) in regulating cancer progression and anti-tumor immunity and open new avenues for developing NK cell-based immunotherapies for PDAC patients. Citation Format: Kamiya Mehla. Nutrient competition in the tumor microenvironment alters NK cell metabolism in Pancreatic Cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A021.

Effects of different allo-Treg/allo-NK ratios on graft-versus-host disease in transplanted mice

To investigate the effects of allo-Treg cells, allo-NK cells, and their mixtures in different proportions on Graft-versus-host disease (GVHD) in bone marrow transplant mouse model. In this study, C57BL/6 mice were used as donors, and 6 Gy dose of 60Co γ was used as the receptor of BALB/c mice. The recipient mice were divided into NC (normal saline), CON (bone marrow cells), NK (bone marrow cells + NK cells), Treg (bone marrow cells + Treg cells), NK+ Treg (1:1) (bone marrow cells +1:1 ratio of Treg cells, NK cells), and NK+ Treg (6:1) (bone marrow cells +1:6 ratio of Treg cells, NK cells), according to the different injection mode through the tail vein. The differences of white blood cell (WBC), platelet (PLT), clinical manifestations, and GVHD score of target organs (liver, lung, small intestine) in each group after transplantation were observed, and the differences of chimerism rate and survival rate in each group at 28 days after transplantation were compared. The interaction between Treg cells and NK cells in different proportions (1:1, 1:2, 1:6, 1:12) was investigated in vitro in mouse erythroleukemia (MEL) cells of mouse erythroleukemia. The results showed that at the 28th day of transplantation, the clinical manifestations and GVHD scores of target organs of mice in NK+ Treg (1:1) group and NK+ Treg (6:1) group were significantly lower than other groups (P < 0.05); the WBC and PLT counts were significantly higher than other groups (P < 0.05), and the survival time was significantly longer than other groups (P < 0.05); the clinical manifestations and GVHD scores of each target organ in NK+ Treg (1:1) group were significantly lower than those in NK+ Treg (6:1) group (P < 0.05); the chimerism rate of each group was >90% on day 28 after transplantation. In vitro experiments showed that the inhibition of Treg cells on NK cell killing activity was dose-dependent, and the proportion of 1:6 and 1:12, killing activity of NK cell was significantly lower than that of groups 1:1 and 1:2 (P < 0.05), which showed that allo-NK and allo-Treg alone had a significant effect on the improvement of GVHD after transplantation, and Treg cells inhibited the killing activity of NK cells by direct contact and showed a dose-dependent effect.

AATF/Che-1 RNA polymerase II binding protein overexpression reduces the anti-tumor NK-cell cytotoxicity through activating receptors modulation.

AATF/Che-1 over-expression in different tumors is well known and its effect on tumorigenicity is mainly due to its central role demonstrated in the oncogenic pathways of solid tumors, where it controls proliferation and viability. The effect exerted by tumors overexpressing Che-1 on the immune response has not yet been investigated. Starting from ChIP-sequencing data we confirmed Che-1 enrichment on Nectin-1 promoter. Several co-cultures experiments between NK-cells and tumor cells transduced by lentiviral vectors carrying Che-1-interfering sequence, analyzed by flow-cytometry have allowed a detailed characterization of NK receptors and tumor ligands expression. Here, we show that Che-1 is able to modulate the expression of Nectin-1 ligand at the transcriptional level, leading to the impairment of killing activity of NK-cells. Nectin-1 down-modulation induces a modification in NK-cell ligands expression able to interact with activating receptors and to stimulate NK-cell function. In addition, NK-cells from Che-1 transgenic mice, confirming a reduced expression of activating receptors, exhibit impaired activation and a preferential immature status. The critical equilibrium between NK-cell ligand expression on tumor cells and the interaction with NK cell receptors is affected by Che-1 over-expression and partially restored by Che-1 interference. The evidence of a new role for Che-1 as regulator of anti-tumor immunity supports the necessity to develop approaches able to target this molecule which shows a dual tumorigenic function as cancer promoter and immune response modulator.

Immunomodulatory activity of semen Ziziphi Spinosae protein: a potential plant protein functional food raw material

Semen Ziziphi Spinosae protein (SZSP) is a new plant protein resource with good food functional properties and health care function. However, the biological activity of SZSP has not been further studied, which greatly limits the development and utilization of SZSP in the food industry. The aim of this study was to investigate the protective effect of SZSP on immunosuppressed mice and its inhibitory effect on immune-stimulated RAW264.7 cells. The results demonstrated that SZSP remarkably improved the immunomodulatory secretion in serum (interleukin-2, tumor necrosis factor-α [TNF-α], interferon-γ, immunoglobulin-A, immunoglobulin-G, immunoglobulin-M) and primary macrophages (nitric oxide, interleukin-1β, TNF-α) and promoted the NK-cell killing activity of primary splenocytes in CTX-induced immunosuppression mice. Immunohistochemical analysis results indicated that the secretion of CD4+ and CD8+ in the spleen and thymus can be regulated by SZSP, leading to inhibition of the damage induced by cyclophosphamide in mice. Meanwhile, in order to clarify the immunomodulatory mechanism of SZSP, we showed that SZSP significantly inhibited the secretion of NO, interleukin-6, and TNF-α and reduced the phosphorylation expression of p-ERK, p-JNK, and p-IκBα in lipopolysaccharide-stimulated RAW264.7 cells. Therefore, the immunomodulatory effect of SZSP may be related to the activation of MAPKs and NF-κB signaling pathways. Based on the above studies, the preliminary purification of SZSP was continued, and S1F2G1 with immunomodulatory activity was obtained. Taken together, SZSP has an immunoregulatory effect in vivo and in vitro and may be a favorable candidate of functional food raw material for regulating immune responses.

Clinical Significance of Plasma Soluble MICB in Children With EBV-associated Hemophagocytic Lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a potentially fatal systemic inflammation disease in children. The most common cause is Epstein-Barr virus (EBV) infection. MHC class I polypeptide-related sequence B (MICB) is a membrane protein inducibly expressed upon cellular stress, viral infection, or malignant transformation, thus marking these cells for clearance through natural killer group 2 member D-positive lymphocytes. MICB can be released into plasma through several mechanisms, reducing NK cell cytotoxicity. We conducted clinical research on HLH patients and cell research in vitro. In the retrospective clinical part, 112 HLH patients (including EBV-HLH group and non-EBV-HLH group), 7 infectious mononucleosis patients, and 7 chronic active EBV infection patients were treated in Beijing Children's Hospital, affiliated with Capital Medical University, from January 2014 to December 2020, were enrolled in this study. Real-time quantitative polymerase chain reaction, standard enzyme-linked immunosorbent assay methods, and lactate dehydrogenase release tests were used to examine the expression of MICB mRNA, the soluble MICB (sMICB) levels, and the activity of NK cells in those patients. In vitro research, MICB overexpression-vector virus, MICB knockdown-vector virus, and empty-vector virus were transfected into two kinds of target cells, such as K562 and MCF7. The level of sMICB and NK cell killing activity between other groups was compared. Finally, we compared NK92 cell killing activity in different concentrations of sMICB. In clinical studies, compared with the non-EBV-HLH group, the EBV-HLH group had lower NK cell killing activity ( P < 0.05). The level of sMICB in the EBV-HLH group was significantly higher than in non-EBV-HLH, infectious mononucleosis, and chronic active EBV infection patients ( P ＜0.05). A high level of sMICB was associated with poor treatment response and poor prognosis ( P ＜0. 05). Cellular studies showed that an increased level of membrane MICB could positively correlate with the killing activity of NK92 cells ( P ＜0. 05), and a high level of sMICB (1250 to 5000pg/ml) could reduce the killing activity of NK92 cells ( P < 0.05). A high level of sMICB (2500pg/ml) could increase the release of cytokines from NK92 cells. The expression level of sMICB in EBV-HLH patients increased, and a high level of sMICB at the initial onset indicated a poor treatment response. The killing activity of NK cells in EBV-HLH patients decreased more significantly. The high level of sMICB may inhibit the killing activity but increase the release of cytokines of NK92 cells.

Immunopotentiation effects of apigenin on NK cell proliferation and killing pancreatic cancer cells.

Apigenin is a kind of flavonoid with many beneficial biological effects. It not only has direct cytotoxicity to tumor cells, but also can boost the antitumor effect of immune cells by modulating immune system. The purpose of this study was to investigate the proliferation of NK cells treated with apigenin and its cytotoxicity to pancreatic cancer cells in vitro, and explore its potential molecular mechanism. In this study, the effect of apigenin on NK cell proliferation and killing pancreatic cancer cells were measured by CCK-8 assay. Perforin, granzyme B (Gran B), CD107a, and NKG2D expressions of NK cells induced with apigenin were detected by flow cytometry (FCM). The mRNA expression of Bcl-2, Bax and protein expression of Bcl-2, Bax, p-ERK, and p-JNK in NK cells were evaluated by qRT-PCR and western blotting analysis, respectively. The results showed that appropriate concentration of apigenin could significantly promote the proliferation of NK cells in vitro and enhance the killing activity of NK cells against pancreatic cancer cells. The expressions of surface antigen NKG2D and intracellular antigen perforin and Gran B of NK cells were upregulated after treating with apigenin. Bcl-2 mRNA expression was increased, while Bax mRNA expression was decreased. Similarly, the expression of Bcl-2, p-JNK, and p-ERK protein was upregulated, and the expression of Bax protein was downregulated. The molecular mechanism of the immunopotentiation effects of apigenin may be that it up-regulates Bcl-2 and down-regulates Bax expression at the gene and protein levels to facilitate NK cell proliferation, and up-regulates the expression of perforin, Gran B, and NKG2D through the activation of JNK and ERK pathways to enhance NK cell cytotoxicity.

Preparation of Water-Soluble Acetylaminoglucan with Low Molecular Weight and Its Anti-Tumor Activity on H22 Tumor-Bearing Mice.

In this study, a novel low molecular weight of acetylaminoglucan (AGA) was obtained and its antitumor activity on H22 tumor-bearing mice was investigated. The results of UV, HPLC and FT-IR showed that AGA present high purity with low molecular weight of 2.76 × 103 Da. Animal experiments showed that AGA could inhibit the proliferation of tumor cells in H22 tumor-bearing mice by protecting the immune organs, enhancing the phagocytosis ability of macrophages, killing activity of NK cells and proliferation capacity of lymphocytes, improving the levels of cytokines in vivo and regulating the distribution of lymphocyte subsets, and the tumor inhibition rate reached to 52.74% (50 mg/kg). Cell cycle determination further indicated that AGA could induce apoptosis of tumor cells and arrests it in S phase. These results will provide a data basis for the potential application of AGA in pharmaceutical industry.

Venetoclax enhances NK cell killing sensitivity of AML cells through the NKG2D/NKG2DL activation pathway

BackgroundVenetoclax, a selective B-cell lymphoma-2 (BCL2) inhibitor, has a potential therapeutic effect when combined with demethylating agents in the first-line setting of unfit elderly patients with acute myeloid leukaemia (AML); however, efficacy is still limited in refractory/recurrent AML. Therefore, exploration of a suitable novel treatment scheme is urgently needed.However, combining venetoclax with NK cell-based immunotherapy has not been studied. MethodsThe cytotoxicity of NK cell combined with venetoclax was assessed in vitro using flow cytometry. Venetoclax-induced natural killer group 2 member D (NKG2D) ligand (NKG2DL) expression was detected by flow cytometry and western blotting. Mechanisms underlying venetoclax-induced NKG2DL expression were found by GSE127200 analysis and investigated using real-time PCR (Q-PCR) and western blotting. ResultsFlow cytometric analysis showed that combining venetoclax with NK cells produced synergistic anti-leukaemia effects similar to those of venetoclax + azacitidine. Venetoclax could render AML cell lines and primary AML cells sensitive to NK cell killing by promoting NK cell degranulation, NK-AML cell recognition and NK cell secretion of interferon (IFN)-γ and granzyme B. The synergistic effect resulted from venetoclax-induced NKG2DL upregulation in AML cells and could be undermined by blocking NKG2D on NK cells. This finding suggests that venetoclax enhances NK cell killing activity by activating the NKG2D/NKG2DL ligand–receptor pathway. Furthermore, the nuclear factor-kappa-B (NFKB) signalling pathway was involved in venetoclax-induced NKG2DL upregulation. ConclusionsCollectively, our data confirm that venetoclax combined with NK cells induces synergistic AML cell cytolysis and preliminarily revealed that venetoclax could selectively induce NKG2DLs on AML cells via NFKB signalling pathway.

Diterpenoids from Euphorbia helioscopia and their enhancement of NK cell-mediated killing of NSCLC cells

Fourteen previously undescribed diterpenoids, including an unusual diterpenoid (1) with a 9,10-seco-jatrophane skeleton, ten jatrophane-type diterpenoids (2–11), two lathyrane-type diterpenoids (12, 13), and an abietane-type diterpenoid (14), together with thirty-six known ones (15–50), were isolated from the whole plants of Euphorbia helioscopia L. The structures of the new isolates were characterized by spectroscopic methods, single-crystal X-ray diffraction analysis, and computational prediction of ECD and chemical shifts. Thirty-nine abundant diterpenoids were evaluated for their enhancement of NK cell-mediated killing of NSCLC cells. As a result, compounds 24, 33, and 41 were found to significantly enhance the killing activity of NK cells towards H1299-luci cells and A549-luci cells at the concentration of 2.5 μM.

Abstract CT053: Use of CRISPR knock-out screen to identify genes that regulate tumor cell sensitivity to NK cell-based immunotherapy

Abstract Natural killer (NK) cells play a key role in tumor immune surveillance by their ability to recognize and kill both hematological and solid tumor cells. NK cell-based immunotherapy is emerging as a powerful treatment against certain malignancies. However, intrinsic and extrinsic mechanisms can lead tumor cells to develop resistance mechanisms to escape NK cell-mediated killing, including up or down-regulation of genes involved in the interaction between tumor and immune cells. Here, we use a “two cell type” (TCT) screening system to identify novel molecular targets regulating NK cell-mediated killing of glioblastoma stem cells (GSC), meningioma cells, as well as head and neck squamous cells carcinomas (HNSCC). By using a whole genome-scale CRISPR-Cas9 library, we induced mutations in tumor cells to mimic loss of function mutations involved in resistance or sensitivity to NK cells. After a round of selection with human peripheral blood NK cells, we profiled the genes that impaired the killing activity of NK cells or increased the sensitivity of tumor cells to NK cells. The most common genes lost in GSC and meningioma cells that lead to increased sensitivity to NK cells are involved in the ER-phagosome pathway, antigen presentation and cellular localization. We then used GSC to validate our top genetic hits identified by the screening. One gene of interest, CHMP2A is a component of ESCRT-III, a complex involved in multi vesicular bodies and exosomes formation known to be involved in intercellular communications, mediating numerous physiological processes among which immunology and tumor biology. We confirmed that impaired expression of CHMP2A in GSC lines increases their sensitivity to NK cell-mediated killing. RNA sequencing demonstrates knock-out (KO) of CHMP2A leads to increased expression of immune response genes, including certain chemokines. Indeed, NK cells demonstrated increased migration towards KO GSC corresponding to higher concentrations of CXCL10, CXCL12 and IL-8 in GSC-KO conditioned media. Since HNSCC are among the most highly immune-infiltrated cancer types, including a high degree of infiltrating NK cells, we next tested CHMP2A-KO-Cal27 cells as a model of HNSCC. Again, we observed an increased sensitivity to NK cells, higher levels of CXCL10 and increased migration of NK cells, demonstrating these mechanisms regulate NK cell-mediated killing of diverse tumor types. Additionally, in vivo studies using a Cal27 xenograft model and adoptive transfer of human NK cells in immunodeficient mice demonstrate increased NK cell-mediated killing of CHMP2A-KO-Cal27 cells compared to wild type Cal27 cells. Together, these studies demonstrate the utility of a TCT screen to identify new mechanisms that mediate resistance of diverse tumor types to NK cell-mediated killing and allow us to now identify novel strategies to further improve this immunotherapeutic approach. Citation Format: Davide Bernareggi, Qi Xie, Briana Prager, Li Xiqing, Silvio Gutkind, Dan S. Kaufman. Use of CRISPR knock-out screen to identify genes that regulate tumor cell sensitivity to NK cell-based immunotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT053.

Abstract PR03: Use of CRISPR knockout screen to identify genes that regulate tumor cell sensitivity to NK cell-based immunotherapy

Abstract Natural killer (NK) cells play a key role in tumor immune surveillance by their ability to recognize and kill both hematologic and solid tumor cells. NK cell-based immunotherapy is emerging as a powerful treatment against certain malignancies. However, intrinsic and extrinsic mechanisms can lead tumor cells to develop resistance mechanisms to escape NK cell-mediated killing, including up- or downregulation of genes involved in the interaction between tumor and immune cells. Here, we use a “two cell type” (TCT) screening system to identify novel molecular targets regulating NK cell-mediated killing of glioblastoma stem cells (GSC), meningioma cells, as well as head and neck squamous cell carcinomas (HNSCC). By using a whole genome-scale CRISPR-Cas9 library, we induced mutations in tumor cells to mimic loss of function mutations involved in resistance or sensitivity to NK cells. After a round of selection with human peripheral blood NK cells, we profiled the genes that impaired the killing activity of NK cells or increased the sensitivity of tumor cells to NK cells. The most common genes lost in GSC and meningioma cells that lead to increased sensitivity to NK cells are involved in the ER-phagosome pathway, antigen presentation, and cellular localization. We then used GSC to validate our top genetic hits identified by the screening. One gene of interest, CHMP2A, is a component of ESCRT-III, a complex involved in multivesicular bodies and exosomes formation known to be involved in intercellular communications, mediating numerous physiologic processes among which are immunology and tumor biology. We confirmed that impaired expression of CHMP2A in GSC lines increases their sensitivity to NK cell-mediated killing. RNA sequencing demonstrates knockout (KO) of CHMP2A leads to increased expression of immune response genes, including certain chemokines. Indeed, NK cells demonstrated increased migration towards KO GSC corresponding to higher concentrations of CXCL10, CXCL12, and IL-8 in GSC-KO conditioned media. Since HNSCC are among the most highly immune-infiltrated cancer types, including a high degree of infiltrating NK cells, we next tested CHMP2A-KO-Cal27 cells as a model of HNSCC. Again, we observed an increased sensitivity to NK cells, higher levels of CXCL10, and increased migration of NK cells, demonstrating these mechanisms regulate NK cell-mediated killing of diverse tumor types. Additionally, in vivo studies using a Cal27 xenograft model and adoptive transfer of human NK cells in immunodeficient mice demonstrate increased NK cell-mediated killing of CHMP2A-KO-Cal27 cells compared to wild-type Cal27 cells. Together, these studies demonstrate the utility of a TCT screen to identify new mechanisms that mediate resistance of diverse tumor types to NK cell-mediated killing and allow us to now identify novel strategies to further improve this immunotherapeutic approach. This abstract is also being presented as Poster A25. Citation Format: Davide Bernareggi, Qi Xie, Briana Prager, Li Xiqing, Silvio Gutkind, Dan S. Kaufman. Use of CRISPR knockout screen to identify genes that regulate tumor cell sensitivity to NK cell-based immunotherapy [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr PR03.

Expansion of natural killer cells with optimal killing activity for cancer immunotherapy

Abstract Natural killer (NK) cells play a key role in the elimination of microbial pathogens and cancer cells. NK cells rapidly respond to stressed cells that are infected or bear tumorigenic mutations that reduce “self” markers of MHC class 1 and/or display increased presentation of activating ligands. These signals prompt NK cells to form an immunological synapse with an infected or tumor cell and discharge lytic granules containing cytotoxic proteins such as IFNγ, perforin and granzyme B leading to target cell destruction. Because of their natural ability to recognize and kill cancer cells, a plethora of preclinical studies and clinical trials have shown that NK cell therapies offer a potentially powerful weapon to fight both advanced-stage blood cancers and solid tumors. Given the great potential of NK cell therapies, we developed clinically relevant serum- and xeno-free methods for human NK cell expansion. Using optimized media and cytokines, either with anti-NKp46 coated tissue culture dishes or Cloudz™ CD2/NKp46 microspheres we have greatly expanded highly purified NK cells from human peripheral blood mononuclear cells (PBMCs) that are capable of potent cytolytic activity, as indicated with a novel flow cytometry-based NK cytotoxicity assay. Using this NK expansion methodology, we performed high-throughput screening methods to identify novel agents that enhance NK cell killing activity as assessed by IFNγ and Granzyme B quantikine ELISA assays which were then confirmed with NK cytotoxicity assays. The methods established here provide a novel workflow for generating highly purified NK cells that are applicable to clinical translation. Furthermore, the agents identified in this work provide insight for augmenting NK killing potential.

Abstract A95: A genome-wide CRISPR screen identifies novel ligands for the Siglec family of glyco-immune checkpoint receptors

Abstract Cancer cells are frequently characterized by extensive remodeling of their cell surface glycocalyx, the complex pattern of sugar modifications that decorate cell surface proteins. In particular, cancer cells often overexpress an unusually high density of sialic acid glycans on their plasma membrane. This modification shields tumors from immune detection through engagement of inhibitory Siglec (Sialic acid-binding immunoglobulin-type lectin) receptors, which are widely expressed in innate immune cells. Blockade of these Siglec-based immune checkpoints has shown the potential to increase immune activity against highly sialylated cancer cells. The specific glycosylated ligands that serve as counter-receptors for Siglecs, however, are not well characterized. Here we describe a strategy for better defining these immune checkpoints using a CRISPR-based genetic screening approach. A library of gRNAs was screened using FACS to identify genes whose ablation significantly reduced cell-surface binding of recombinantly expressed, fluorescently labeled Siglecs. We thereby generated a list of genes with putative roles in driving the cell-surface expression of sialic acid-containing Siglec ligands. Our screen correctly identified known genes involved in sialic acid biosynthesis, validating the specificity of this approach. Additionally, this screen revealed that knockdown of a single heavily O-glycosylated protein plasma membrane protein dramatically reduced binding of Siglec7, the Siglec receptor expressed specifically in NK cells. Follow-up work has shown that Siglec7 binds to this ligand with high affinity and that genetic blockade of this interaction potentiates NK cell killing activity in vitro. This study has thus defined a novel and specific glyco-immune interaction with potential significance in driving tumor escape from innate immune surveillance. Citation Format: Simon Wisnovsky, Carolyn Bertozzi. A genome-wide CRISPR screen identifies novel ligands for the Siglec family of glyco-immune checkpoint receptors [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A95.

Synergistic and toxicity-attenuating effects of Periplaneta americana extract CII-3 combined with cisplatin on lewis lung cancer-bearing mice

Objective: The objective was to study the synergistic and attenuating effects of CII-3 combined with cisplatin. Materials and Methods: A Lewis tumor-bearing mouse model was established. After 15 days of continuous administration of CII-3 and cisplatin, the pathological changes in the tumor, liver, lung, and femur tissues were observed; the life prolongation rate, tumor inhibition rate, Q value, organ indices, spleen T- and B-lymphocyte proliferation activities, NK cell killing activity, the bone marrow cell proliferation rate and cell cycle phase, and the number of peripheral blood cells and bone marrow nucleated cells were measured. The expression of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in mouse serum and bone marrow tissue was measured. Results: The combination of CII-3 and cisplatin could enhance the ability of cisplatin to inhibit tumor cell proliferation and protects the liver damage and femoral injury and could significantly increase the life prolongation rate; tumor inhibition rate of cisplatin; the liver, spleen, lung, and thymus indices; the T- and B-lymphocyte proliferation activity; the NK cell killing activity; and the number of peripheral blood cells and bone marrow nucleated cells. The combination of drugs can stimulate the transformation of bone marrow cells from S phase to G2/M phase, significantly increase the proliferation rate of bone marrow cells and the contents of G-CSF and GM-CSF in mouse serum, and downregulate the mRNA and protein levels of them in bone marrow tissue. Conclusion: These results suggest that CII-3 combined with cisplatin can significantly enhance the antitumor effect and reduce the toxicity and side effects of cisplatin in Lewis tumor-bearing mice.

Impacts of functional oligosaccharide on intestinal immune modulation in immunosuppressive mice.

In order to research the role of soybean oligosaccharides (SBOSs) on improvements in the microenvironment of intestinal flora and immune function of cyclophosphamide (CTX) immunosuppressive mice. Via giving intragastric administration of Soybean oligosaccharide (SBOS) at the low dose (50/(kg·BW)/d), the middle dose (200 mg/(kg·BW)/d) and the high dose (500 mg/(kg·BW)/d) partly once a day, which is also 28 days in a row. At the same time, (SBOS) mice in the drug group and (CG) mice in the positive control group were given intraabdominal injection of CTX (200 mg/kg/d).The immunosuppressive mouse model (CY) was established after 72 h in the model group and the positive control group (CG) was given intragastric administration of levamisole hydrochloric acid (LMS) for 3 days, with the data of 80ug/kg/d after injection of CTX (for actually 72 h). On the 8th, 15th and 22nd day, the number of Bifidobacterium, Lactobacillus, Enterococcus and Clostridium perfringens m in the feces of mice in each dose of drug group were determined. After the test resulted, the cellular immune function, humoral immune function, monocyte/macrophage function, NK cell activity and cytokine secretion (tumor necrosis factor-α, interferon-gamma and IL-4) were measured in immunosuppressive mice each group. The results showed that 200 mg/(kg BW) soybean oligosaccharide could significantly promote the proliferation and inhibit the increase of Enterococcus in immunosuppressive mice. The soybean oligosaccharide of 500 mg/(kg BW) could dramatically promote the proliferation of both Bifidobacillus and Lactobacillus, and also inhibit the increase of both Enterobacteriaceae and Enterococcus in immunosuppressive mice. The regulatory function of SBOS on intestinal flora was positive. Soybean oligosaccharide (500 mg/(kg BW) could significantly promote the proliferation of Bifidobacillus and Lactobacillus in immunosuppressive mice and inhibit the increase of Enterococcus and Enterococcus. The proliferation of spleen lymphocytes induced by ConA, LPS in immunosuppressive mice was dose-dependent. But it was still lower than that of the normal group (CG0) (p > 0.05). The serum hemolysin level of immunosuppressive mice was significantly increased in each dose group (p < 0.05), and the level of antibody forming cells in spleen cells of each dose group was significantly increased (P < 0.05), and the level of antibody forming cells in spleen cells of each dose group was significantly higher than that of low dose group (p < 0.005), and the level of serum hemolysin in immunosuppressive mice was significantly increased in each dose group (p < 0.05). In the detection of immune effector cell activity in immunosuppressive mice, the phagocytic function of macrophages in high dose group and the natural killing activity of spleen NK cells in high dose drug group were significantly increased, which were not significantly different from those in positive control group (P < 0.05), but the expression of TNF-α, INF-γ and IL-4 cytokines in serum was increased in a dose dependent manner (p < 0.05). In conclusion, soybean oligosaccharide can significantly increase the diversity of intestinal microecology, increase the number of intestinal beneficial bacteria, has a correlation with the proliferation of Bifidobacterium and Lactobacillus in the intestinal tract, and inhibit the proliferation of harmful bacteria. The results showed that SBOS had a direct effect on the proliferation of intestinal flora under immunosuppression. Based on the improvement of intestinal microenvironment in immunosuppressive mice by soybean oligosaccharide for 25 days, the results showed that compared with the positive control group, the nonspecific and specific immunity of immunosuppressive mice in the drug group had a regulatory effect, which improved the phagocytic function of monocytes/macrophages, developed the level of antibody forming cells, enhanced the standard of the killing activity of NK cells, and promoted the expression of cytokines as well. Compared with the model group, the transformation and proliferation of spleen lymphocytes in the high and middle dose groups were remarkably increased, but all of the indexes did not reach the level of the normal blank group. By studying the improvement of intestinal microenvironment in immunosuppressive mice, to some extent, it is concluded that the proliferation of intestinal flora can improve the immunomodulatory function of the body, but it still lowers the normal immune degree, which reflects the immunomodulatory effect of the body on the stimulation of continuous external intake. The results demonstrate that the immunomodulatory ability of immunosuppressive body was insensitive to SBOS and provided a theoretical basis for the study of health care function of intestinal microenvironment improvement when SBOS acted on abnormal immune function. The results also improved the practical application value of SBOS.

HO-1 downregulation favors BRAFV600 melanoma cell death induced by Vemurafenib/PLX4032 and increases NK recognition.

Heme oxygenase 1 (HO-1) plays a pivotal role in preventing cell damage. Indeed, through the antioxidant, antiapoptotic and anti-inflammatory properties of its metabolic products, it favors cell adaptation against different stressors. However, HO-1 induction has also been related to the gain of resistance to therapy in different types of cancers and its involvement in cancer immune-escape has been hypothesized. We have investigated the role of HO-1 expression in Vemurafenib-treated BRAFV600 melanoma cells in modulating their susceptibility to NK cell-mediated recognition. Different cell lines, isolated in house from melanoma patients, have been exposed to 1-10 μM PLX4032, which efficiently reduced ERK phosphorylation. In three lines, Vemurafenib was able to induce only a limited decrease in cell viability, while HO-1 expression was upregulated. HO-1 silencing/inhibition was able to induce a further significant reduction of Vemurafenib-treated melanoma viability. Moreover, while NK cell degranulation and killing activity were decreased upon interaction with melanoma exposed to Vemurafenib, HO-1 silencing was able to completely restore NK cell ability to degranulate and kill. Furthermore, melanoma cell treatment with Vemurafenib downregulated the expression of ligands of NKp30 and NKG2D activating receptors, and HO-1 silencing/inhibition was able to restore their expression. Our results indicate that HO-1 downregulation can both improve the efficacy of Vemurafenib on melanoma cells and favor melanoma susceptibility to NK cell-mediated recognition and killing.

Hypoxia-inducible gene 2 promotes the immune escape of hepatocellular carcinoma from nature killer cells through the interleukin-10-STAT3 signaling pathway

BackgroundThe study examines the expression and function of hypoxia-inducible gene 2 (HIG2) in hepatocellular carcinoma (HCC) tissues and cells.MethodsForty patients with HCC were included in the study. Bioinformatic analysis was used to analyze the clinical relevance of HIG2 expression in HCC tissue samples. Immunohistochemistry was employed to determine the expression of target proteins in tumor tissues. Hepatic HepG2 and SMMC-7721 cells were transfected with HIG2-targeting siRNA with Lipofectamine 2000. qRT-PCR was carried out to determine gene expression levels, while Western blotting was used to determine protein expression. A CCK-8 assay was performed to detect proliferation of cells, while migration and invasion of cells were studied by Transwell assay. Flow cytometry was carried out to detect surface markers and effector molecules in Nature killercells, as well as the killing effect of NK cells.ResultsHIG2 expression was upregulated in HCC. Silencing of HIG2 suppressed HCC cell migration and invasion. The killing effect of NK cells on HCC cells was enhanced after HIG2 was silenced in HCC cells. Conditioned media from HIG2-silenced SMMC-7721 cells inhibited the phenotype and function of NK cells. HCC cells with silenced expression of HIG2 modulated the activity of NK cells via STAT3. HIG2 promoted the evasion of HCC cells from killing by NK cells through upregulation of IL-10 expression.ConclusionThe study demonstrates that HIG2 activates the STAT3 signaling pathway in NK cells by promoting IL-10 release by HCC cells, thereby inhibiting the killing activity of NK cells, and subsequently promoting the recurrence and metastasis of HCC.

Preliminary Structural Characteristics of Polysaccharides from Pomelo Peels and Their Antitumor Mechanism on S180 Tumor-Bearing Mice.

In this study, the polysaccharides (PPs) from pomelo peels were investigated for their structural characteristics and antitumor mechanism on sarcoma S180-bearing mice. Components, FT-IR, and GC analysis showed that PPs, mainly composed of glucose, were typical acid polysaccharides with α-d-pyranoid glucose containing 74.52% carbohydrate and 16.33% uronic acid. The in vivo antitumor tests revealed that PPs could effectively suppress the transplanted S180 tumors growth, as well as protect the immune organs, improve proliferation ability of splenic lymphocytes and killing activity of NK cells in tumor-bearing mice. Furthermore, the levels of serum cytokines (IL-2, IFN-γ and TNF-α) and the proportion of CD4+ T cells in peripheral blood of mice bearing S180 tumors were also significantly increased after treatment with PPs. Meanwhile, the transplanted S180 tumor cells exhibited obvious apoptotic phenotype after PPs treatment by arresting the cell cycle in S phase, down-regulating the Bcl-2 expressions and up-regulating the Bax levels. These data showed that PPs were mainly composed of glucose with α-d-pyranoid ring and could induce apoptosis of solid tumor cells by enhancing the antitumor immunity of tumor-bearing mice, which would provide a theoretical basis for the practical application in food and medical industries.

A purified, fermented, extract of Triticum aestivum has lymphomacidal activity mediated via natural killer cell activation.

Non-Hodgkin lymphoma (NHL) affects over 400,000 people in the United States; its incidence increases with age. Treatment options are numerous and expanding, yet efficacy is often limited by toxicity, particularly in the elderly. Nearly 70% patients eventually die of the disease. Many patients explore less toxic alternative therapeutics proposed to boost anti-tumor immunity, despite a paucity of rigorous scientific data. Here we evaluate the lymphomacidal and immunomodulatory activities of a protein fraction isolated from fermented wheat germ. Fermented wheat germ extract was produced by fermenting wheat germ with Saccharomyces cerevisiae. A protein fraction was tested for lymphomacidal activity in vitro using NHL cell lines and in vivo using mouse xenografts. Mechanisms of action were explored in vitro by evaluating apoptosis and cell cycle and in vivo by immunophenotyping and measurement of NK cell activity. Potent lymphomacidal activity was observed in a panel of NHL cell lines and mice bearing NHL xenografts. This activity was not dependent on wheat germ agglutinin or benzoquinones. Fermented wheat germ proteins induced apoptosis in NHL cells, and augmented immune effector mechanisms, as measured by NK cell killing activity, degranulation and production of IFNγ. Fermented wheat germ extract can be easily produced and is efficacious in a human lymphoma xenograft model. The protein fraction is quantifiable and more potent, shows direct pro-apoptotic properties, and enhances immune-mediated tumor eradication. The results presented herein support the novel concept that proteins in fermented wheat germ have direct pro-apoptotic activity on lymphoma cells and augment host immune effector mechanisms.

Bitter Melon Enhances Natural Killer-Mediated Toxicity against Head and Neck Cancer Cells.

Natural killer (NK) cells are one of the major components of innate immunity, with the ability to mediate antitumor activity. Understanding the role of NK-cell-mediated tumor killing in controlling of solid tumor growth is still in the developmental stage. We have shown recently that bitter melon extract (BME) modulates the regulatory T cell (Treg) population in head and neck squamous cell carcinoma (HNSCC). However, the role of BME in NK-cell modulation against HNSCC remains unknown. In this study, we investigated whether BME can enhance the NK-cell killing activity against HNSCC cells. Our results indicated that treatment of human NK-cell line (NK3.3) with BME enhances ability to kill HNSCC cells. BME increases granzyme B accumulation and translocation/accumulation of CD107a/LAMP1 in NK3.3 cells exposed to BME. Furthermore, an increase in cell surface expression of CD16 and NKp30 in BME-treated NK3.3 cells was observed when cocultured with HNSCC cells. Collectively, our results demonstrated for the first time that BME augments NK-cell-mediated HNSCC killing activity, implicating an immunomodulatory role of BME. Cancer Prev Res; 10(6); 337-44. ©2017 AACR.