NK Cell Effector Research Articles

PP2A negatively regulates NK cell T-bet expression and anti-tumor effector function.

The transcription factor T-bet is essential for the anti-tumor effector function of NK cells, but the mechanism regulating its expression in NK cells remains unclear. In this study, we aimed to identify an NK cell intrinsic regulator that controls T-bet expression. Using T-bet-luciferase reporter assay screening, we identified a protein phosphatase inhibitor as a potential activator of T-bet expression. A series of PP2A-specific inhibitors (PP2Ai) or PP2A siRNA induced the expression of T-bet. In PP2Ai-treated mice, the expressions of T-bet and its downstream effector molecules, granzyme B and IFN-γ, were also upregulated in NK cells. Mechanistically, PP2Ai increased the phosphorylation of mTOR and ribosomal protein S6 in NK cells, and mTOR inhibitor canceled the effects of PP2Ai in NK cells. Importantly, NK cells isolated from PP2Ai-treated mice showed higher cytotoxicity and IFN-γ production; therefore, they increased the anti-tumor effector function of NK cells. Accordingly, PP2Ai treatment inhibited lung metastasis of B16 melanoma by NK cell- and mTOR-dependent mechanisms. These results suggest that PP2A negatively regulates NK cell T-bet expression and effector function by an mTOR-dependent mechanism.

Targeted Therapy of CEA-CAR-NK Cells Against Colorectal Cancer Cells

Objective: Investigate the cytotoxic effect of CAR-NK cells targeting CEA on colorectal cancer cells with positive CEA expression. Methods: The mRNA and protein levels of CEA in different CRC cell lines were detected by qRT-PCR and Western blot analysis. Lentiviral transduction was used to construct CAR-NK cells and empty vector CON-NK cells targeting CEA. Fluorescence microscopy and WB were used to determine whether the cells successfully constructed and expressed CAR structures. The effector NK cells were co-cultured with target cells, and the levels of LDH, IFN-γ, and GM-CSF were detected. The killing rate of effector cells was calculated, and the release of cytokines during the killing of target cells by different effector cells was compared. Results: The expression level of CEA in colorectal cancer patients was significantly higher than that in normal samples and other tumor samples, and the prognosis survival time of patients with high CEA expression was lower than that of CRC patients with low or no CEA expression (P < 0.05). The CEA expression of the HT29 cell line was significantly higher than that of the SW1116 cell line at both the mRNA and protein levels. CEA-CAR-NK92 cells and CON-NK92 cells expressed green fluorescence under a microscope, and WB results showed that CEA-CAR-NK92 cells successfully expressed the CAR structure. Compared with CON-NK92 cells and NK92 cells, CEA-CAR-NK92 cells effectively killed HT29 cells (P < 0.05). CEA-CAR-NK92 cells secreted a large amount of IFN-γ and GM-CSF during the killing of HT29 cells, while the cytokine secretion of CON-NK92 cells and NK92 cells was not significant (P < 0.05). Conclusion: CAR-NK92 cells targeting CEA can effectively kill CEA-positive colorectal cancer cells.

Longitudinal dynamic single-cell mass cytometry analysis of peripheral blood mononuclear cells in COVID-19 patients within 6 months after viral RNA clearance

This study investigates the longitudinal dynamic changes in immune cells in COVID-19 patients over an extended period after recovery, as well as the interplay between immune cells and antibodies. Leveraging single-cell mass spectrometry, we selected six COVID-19 patients and four healthy controls, dissecting the evolving landscape within six months post-viral RNA clearance, alongside the levels of anti-spike protein antibodies. The T cell immunophenotype ascertained via single-cell mass spectrometry underwent validation through flow cytometry in 37 samples. Our findings illuminate that CD8 + T cells, gamma-delta (gd) T cells, and NK cells witnessed an increase, in contrast to the reduction observed in monocytes, B cells, and double-negative T (DNT) cells over time. The proportion of monocytes remained significantly elevated in COVID-19 patients compared to controls even after six-month. Subpopulation-wise, an upsurge manifested within various T effector memory subsets, CD45RA + T effector memory, gdT, and NK cells, whereas declines marked the populations of DNT, naive and memory B cells, and classical as well as non-classical monocytes. Noteworthy associations surfaced between DNT, gdT, CD4 + T, NK cells, and the anti-S antibody titer. This study reveals the changes in peripheral blood mononuclear cells of COVID-19 patients within 6 months after viral RNA clearance and sheds light on the interactions between immune cells and antibodies. The findings from this research contribute to a better understanding of immune transformations during the recovery from COVID-19 and offer guidance for protective measures against reinfection in the context of viral variants.

Autologous, oncolytic virus-activated killer (VAK) cell therapy to treat malignant pleural and peritoneal effusions.

e20549 Background: OH2 is an attenuated oncolytic Herpes Simplex-2 virus expressing GM-CSF. OH2 replicates only in cancer cells, causing their lysis, which reverses the immunosuppressive tumor microenvironment, leading to tumor regression. OH2 monotherapy is safe and efficacious in phase I-III trials of 300+ patients across several cancer indications. We previously showed that OH2 treated briefly with UV light (UV-OH2) is unable to form plaques yet still able to infect cancer cells and to potently activate human PBMCs, leading to increased antitumor activity in vitro and in animal models. Methods: Translating these findings in humans, 12 stage IV lung cancer patients with malignant pleural or peritoneal effusions were enrolled in an Investigator-Initiated Trial (NCT05565014). Lymphocytes from each patient’s effusions were isolated, incubated in vitro with UV-OH2 for 36-48h, and then re-infused into the patient's pleural or peritoneal cavity. Each patient received 2 cycles of 3 or up to 6 infusions of this Virus Activated Killer (VAK) Autologous Cell Therapy. Results: Effusion volume (EV) measurement and local and whole-body tumor assessments were performed at the beginning and 28 days post VAK treatment. On D28, EV remained stable in 3 patients (SD), whereas 4 of 12 patients recorded a reduction of EV (PR). Notably, subject S004’s PR was maintained for 210 days post-treatment. Evaluation of target lesions per RECIST revealed 4 subjects with PR and 7 with an SD in target lesions. There was no toxicity or treatment-related adverse events. The median patient OS was 384 days (12.8 months), which is up to 4 times the average published OS for stage IV lung cancer with malignant pleural effusions. RNA-Seq analysis indicated increased expression of many T and NK cell effectors and NK cell activating receptors. Importantly, average autologous CD8+ T lymphocytes rose from 53% to 74% in the effusions post VAK-treatment, thereby confirming activation of the patient’s immune system by UV-OH2 (preliminary clinical PoC). Conclusions: In sum, our VAK therapy offers a cost-effective, extremely safe, and patient-friendly autologous treatment that dramatically increases overall survival in patients with essentially no options. Larger scale studies are in the works. Clinical trial information: NCT05565014 .

Effect of TT-816, a novel immune response modifier targeting cannabinoid CB2 receptor, on antitumor immunity and cancer growth.

e14595 Background: The endocannabinoid system is widely expressed in the human body, including the innate and adaptive immune system, where endocannabinoids, Δ9-tetrahydrocannabinol and synthetic ligands regulate immune suppression. The effects of endocannabinoids on immune regulation are primarily mediated by G-protein coupled cannabinoid CB2 receptors (CB2R) via several mechanisms, including immune cell development, migration, proliferation and T and NK cell effector functions. The upregulated expression of CB2R and elevated levels of endocannabinoids have been observed in a variety of tumor microenvironments and are associated with the aggressiveness of cancer. Methods: NK cell function was determined by co-culturing TT-816 pretreated NK cells with K562 cancer cells for 24 hours. The mixed lymphocyte reaction assay was conducted by co-culturing human CD4+ T cells with monocyte-derived dendritic cells. Cell viability was measured by FACS and IFN-g by MSD. The in vivo efficacy of TT-816 was determined in the murine syngeneic B16F10 melanoma and MC38 colorectal cancer models. Tumor-bearing C57BL/6 mice were randomized 6 days after inoculation and treated with vehicle (0.5% CMC, QD) or with TT-816 at 1, 4 or 10 mg/kg (QD) orally, or anti-PD1 (RMP1 14) at 5 mg/kg (Q3D), intraperitoneally. Tumor size and body weight were determined every 2 to 3 days. Data represent mean±SEM. Results: TT-816 concentration-dependently enhanced the functions of NK cells, dendritic cells and T cells. It increased NK cell killing of the human cancer cells and IFN-g production, significantly stimulated the expression of CD86, HLA-DR, IL-12 and TNF-a in monocyte-derived dendritic cells, and enhanced CD4+ T cell proliferation and IFN-g production in a mixed lymphocyte reaction assay. In B16F10 melanoma and MC38 colorectal cancer models, TT-816 dose-dependently inhibited the tumor growth. Furthermore, combination of TT-816 with anti-PD1 synergistically inhibited both tumor growth. In B16F10 model, treatment with TT 816 (4 mg/kg, QD) alone significantly inhibited the tumor growth by 45%. By contrast, anti-PD1 had little effect (TGI 5%). However, the combination of TT-816 with anti-PD1 resulted in a TGI of 72%. In the MC38 model, treatment with TT-816 (4 mg/kg, QD) and anti-PD1 alone, achieved TGI of 50% and 36%, respectively. When combined, TGI was increased to 88%. Conclusions: TT-816 is a novel, oral small molecule immune response modifier that selectively blocks CB2R on immune cells and cancer cells. Preclinical data have demonstrated that it stimulates antitumor immune response and inhibits cancer growth in both hot and cold tumor models. TT-816 is currently undergoing phase 1 clinical trials for the treatment of a broad range of solid tumors.

Ginseng-DF ameliorates intestinal mucosal barrier injury and enhances immunity in immunosuppressed mice by regulating MAPK/NF-κB signaling pathways.

Dietary fiber (DF) has a good application prospect in effectively restoring the integrity of the intestinal mucosal barrier. Ginseng-DF has good physicochemical properties and physiological activity and shows positive effects in enhancing immunity. The aim of this study was to investigate the protective effect of Ginseng-DF on intestinal mucosal barrier injury induced by cyclophosphamide (CTX) in immunosuppressed mice and its possible mechanism. The effects of Gginseng-DF on immune function in mice were studied by delayed-type hypersensitivy, lymphocyte proliferation assay and NK cytotoxicity assay, the T lymphocyte differentiation and intestinal barrier integrity were analyzed by flow cytometry and western blot. Ginseng-DF (2.5% and 5%) could attenuate the inhibition of DTH response by CTX, promote the transformation and proliferation of lymphocytes, and stimulate NK effector cell activity. At the same time, Ginseng-DF could restore the proportion of CD4+/CD8+ T lymphocytes induced by CTX to different extents, improved spleen tissue damage, promoted the secretion of immunoglobulin IgG, and enhanced body immunity. More importantly, Ginseng-DF could up-regulate the contents of TNF-α, IFN-γ, IL-6 and IL-1β in serum and intestine of immunosuppressed mice to maintain the balance between Th1/Th2 cytokines, and improve the permeability of intestinal mucosal barrier. Meanwhile, Ginseng-DF could reduce intestinal epithelial cell apoptosis and improve intestinal adaptive immunity in CTX-induced immunosuppressed mice by regulating MAPK/NF-κB signaling pathway. Ginseng-DF can be used as a safe dietary supplement to enhance body immunity and reduce intestinal mucosal injury caused by CTX.

Fate control engagement augments NK cell responses in LV/hu-IL-12 transduced sarcoma

IntroductionNK cells are an untapped resource for cancer therapy. Sarcomas transduced with lentiviruses to express human IL-12 are only cleared in mice bearing mature human NK cells. However, systemic inflammation limits IL-12 utilization. Fate control a.k.a. “suicide mechanisms” regulate unchecked systemic inflammation caused by cellular immunotherapies. Despite increasing utilization, there remains limited data on immune consequences or tumor-directed effects of fate control. ObjectivesWe sought to engage the mutant thymidylate kinase (mTMPK) metabolic fate control system to regulate systemic inflammation and assess the impact on NK cell effector functions. MethodsPrimary human sarcoma short-passage samples and cell lines were transduced with LV/hu-IL-12_mTMPK engineering expression of IL-12 and an AZT-associated fate control enzyme. We assessed transduced sarcoma responses to AZT engagement and subsequent modulation of NK cell functions as measured by inflammatory cytokine production and cytotoxicity. ResultsAZT administration to transduced (LV/hu-IL-12_mTMPK) short-passage primary human sarcomas and human Ewing sarcoma, osteosarcoma, and rhabdomyosarcoma cell lines, abrogated the robust expression of human IL-12. Fate control activation elicited a specific dose-dependent cytotoxic effect measured by metabolic activity (WST-1) and cell death (Incucyte). NK effector functions of IFN-γ and cytotoxic granule release were significantly augmented despite IL-12 abrogation. This correlated with preferentially induced expression of NK cell activation ligands. ConclusionsmTMPK fate control engagement terminates transduced sarcoma IL-12 production and triggers cell death, but also augments an NK cell-mediated response coinciding with metabolic stress activating surface ligand induction. Fate control engagement could offer a novel immune activation method for NK cell-mediated cancer clearance.

MTOR Signaling Promotes Rapid m6A mRNA Methylation to Regulate NK-Cell Activation and Effector Functions.

NK cells can be rapidly activated in response to cytokines during host defense against malignant cells or viral infection. However, it remains unclear what mechanisms precisely and rapidly regulate the expression of a large number of genes involved in activating NK cells. In this study, we discovered that NK-cell N6-methyladenosine (m6A) methylation levels were rapidly upregulated upon short-term NK-cell activation and were repressed in the tumor microenvironment (TME). Deficiency of methyltransferase-like 3 (METTL3) or METTL14 moderately influenced NK-cell homeostasis, while double-knockout of METTL3/14 more significantly impacted NK-cell homeostasis, maturation, and antitumor immunity. This suggests a cooperative role of METTL3 and METTL14 in regulating NK-cell development and effector functions. Using methylated RNA immunoprecipitation sequencing, we demonstrated that genes involved in NK-cell effector functions, such as Prf1 and Gzmb, were directly modified by m6A methylation. Furthermore, inhibiting mTOR complex 1 activation prevented m6A methylation levels from increasing when NK cells were activated, and this could be restored by S-adenosylmethionine supplementation. Collectively, we have unraveled crucial roles for rapid m6A mRNA methylation downstream of the mTOR complex 1-S-adenosylmethionine signal axis in regulating NK-cell activation and effector functions.

Tumor-associated macrophages impair NK cell IFN-γ production and contribute to tumor progression in clear cell renal cell carcinoma.

Tumor-associated macrophages (TAM) are abundant in several tumor types and usually correlate with poor prognosis. Previously, we demonstrated that anti-inflammatory macrophages (M2) inhibit NK cell effector functions. Here, we explored the impact of TAM on NK cells in the context of clear-cell renal cell carcinoma (ccRCC). Bioinformatics analysis revealed that an exhausted NK cell signature strongly correlated with an M2 signature. Analysis of TAM from human ccRCC samples confirmed that they exhibited an M2-skewed phenotype and inhibited IFN-γ production by NK cells. Moreover, human M0 macrophages cultured with conditioned media from ccRCC cell lines generated macrophages with an M2-skewed phenotype (TAM-like), which alike TAM, displayed suppressive activity on NK cells. Moreover, TAM depletion in the mouse Renca ccRCC model resulted in delayed tumor growth and reduced volume, accompanied by an increased frequency of IFN-γ-producing tumor-infiltrating NK cells that displayed heightened expression of T-bet and NKG2D and reduced expression of the exhaustion-associated co-inhibitory molecules PD-1 and TIM-3. Therefore, in ccRCC, the tumor microenvironment polarizes TAM toward an immunosuppressive profile that promotes tumor-infiltrating NK cell dysfunction, contributing to tumor progression. In addition, immunotherapy strategies targeting TAM may result in NK cell reinvigoration, thereby counteracting tumor progression.

Abstract 2319: Deep learning-enabled dynamic infiltration and response to NK therapies in solid tumor organoids

Abstract Patient-derived organoid co-culture models have become a state of the art platform to evaluate the effectiveness of immunotherapeutic agents in preclinical studies. However, preclinical development as well as quantification of therapeutic potency and resistance require differential labeling of cells with fluorescent dyes or transgenic fluorescent proteins, which may dysregulate the effector cell function or produce undesired cytotoxicity. Deep learning-based image analysis allows the use of brightfield images to co-localize tumor organoids (TOs) with effector cells, and measure TO-specific responses to novel candidate immunotherapies in a label-free manner; this can accelerate their evaluation as therapeutic candidates in cancer patients and shed light on tumor-immune interaction mechanisms. Here we record multi-day time-lapse confocal microscopy images of TOs co-cultured with NK cells at increasing concentrations of target to effector cells. Two pre-trained U-Net convolutional neural networks are used to separately segment tumor and immune cells from the brightfield channel, and quantify immune cell infiltration over time. TO segmentation masks are registered with a vital dye (caspase 3/7) channel to selectively quantify TO cell death and correlate it with estimated immune cell infiltration across a large cohort of patient-derived TO models (including breast, colorectal, endometrial, gastric, head and neck, liver, lung and pancreatic cancer), at increasing concentrations of 6 different NK cell types (identified as A through F). We find that the estimated density of infiltrating immune cells is highly correlated with TO death, as quantified by fluorescence intensity of caspase over time (median Pearson’s r=0.89, P<0.001). Higher ratios of effector to target cells lead to higher activation of NK cells as measured by infiltrating cell density. Differential infiltration dynamics are observed across TOs and immune cell lines, as peak infiltration density is affected by co-culture time, ratio of target to effector cells, TO line, and NK cell type. These findings highlight that the paired segmentation models are able to measure varying degrees of infiltration across different types of immune cells and TO models. The approach described here is highly scalable and only requires capturing brightfield images of the assay, therefore eliminating the need to label cells and avoiding phototoxic effects or alteration of the immune cells activity. Time series measurements enable quantification of patterns of immune cell activation, including infiltration, migration and co-localization dynamics, which provide insights into the pharmacokinetics and mechanisms for specific immune therapies. Overall, this methodology enables high throughput screening of many therapeutic candidates across dozens to hundreds of unique TO-models, thereby facilitating targeted precision therapy. Citation Format: Luca Lonini, Sonal Khare, Timothy Don Lopez, Stanislaw Szydlo, Michael Streit, Olga A. Karginova, Mary K. Flaherty, Ameen Salhaudeen, Andre Kunert, Anna Oja, Kate Sasser, Martin C. Stumpe, Chi-Sing Ho. Deep learning-enabled dynamic infiltration and response to NK therapies in solid tumor organoids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2319.

Abstract 6428: Transcriptome analysis of tissues and peripheral blood revealed potential biomarkers for chemo/radio-immunotherapy in non-small cell lung cancer

Abstract Background: Combination of anti-PD-(L)1 antibody with chemotherapy has shown promising efficacy in advanced/metastatic non-small cell lung cancer (NSCLC). Dynamics of peripheral blood mononuclear cells (PBMC) might have impact on repertore of immune cells further resulting different immune infiltration in tumor microenvironment. Thus, monitoring changes in PBMC during therapy or measuring tumor microenvironment provides the possibility to predict the efficacy of tumor immunotherapy. Methods: Patients diagnosed with NSCLC (Stage III-IV)were enrolled in this study. Anti-PD-L1 and chemo/radio combination therapy was performed as adjuvant therapy. Tumor samples were obtained prior to adjuvant therapy PBMC samples were obtaind at multiple time points, including prior adjuvant therapy, 3 months after adjuvant therapy, and 3 months after adjuvant therapy. Tumor and PBMC mRNA sequencing were performed by Amoy Diagnostics Co Ltd. (Xiamen, China). Patients who achieved CR/PR/SD and PFS > 6 months were defined as well responders. Pathway enrichment and GSEA analyses were performed by clusterProfiler (version 4.0.5) on GO, KEGG, and from six different gene sets. Correlations between immune cellular signature ES scores and gene expression were estimated using Pearson correlation. Results: 28 patients were enrolled; mean age was 60.38±7.86 years, 27 (96.4%) patients were male. 21 (75.0%) patients were identified as responder and 7 (25.0%) were non-responder. In the baseline tumor samples, immune infiltration was more extensive in responders compared to non-responders. Cytotoxic lymphocytes, activated CD8+ T cell, and NK cells were significantly enriched in responders. High expression of CCL17 and down regulation of CTSG/PLK1/PRTN3, a signaling axis that inhibits histone H3 hydrolysis and promotes monocyte to macrophage differentiation, was significant in responders. Dynamic monitoring of PBMC before and after treatment showed significant upregulation of immune infiltration-related pathways in responders, including effector cells, NK cells and CD8+ T cells. In the non-responder group, the up-regulated pathways after treatment were mainly enriched in tumor growth rate, EMT, and matrix remodeling. Multi-time point analysis showed that CEACAM5/MKI67 level and tumor proliferation rate in non-responders were higher than those in responders at each time point after treatment. Conclusion: Baseline tumor transcripton signatures and dynamic changes in PBMC could be applied to develop novel biomarkers for immune-related therapy. Patients with stronger immune infiltration signals in baseline tumor samples and PBMC after treatment had better immune response. The upregulation of proliferation-related signals in PBMC predicts poor immune response. Citation Format: Jing Hu, Jianguo Zhang, Peng Cheng, Yanhua Chen, Changbin Zhu, Feilin Yi, Conghua Xie. Transcriptome analysis of tissues and peripheral blood revealed potential biomarkers for chemo/radio-immunotherapy in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6428.

A single bout of vigorous intensity exercise enhances the efficacy of rituximab against human chronic lymphocytic leukaemia B-cells ex vivo

Chronic lymphocytic leukaemia (CLL) is characterised by the clonal proliferation and accumulation of mature B-cells and is often treated with rituximab, an anti-CD20 monoclonal antibody immunotherapy. Rituximab often fails to induce stringent disease eradication, due in part to failure of antibody-dependent cellular cytotoxicity (ADCC) which relies on natural killer (NK)-cells binding to rituximab-bound CD20 on B-cells. CLL cells are diffusely spread across lymphoid and other bodily tissues, and ADCC resistance in survival niches may be due to several factors including low NK-cell frequency and a suppressive stromal environment that promotes CLL cell survival. It is well established that exercise bouts induce a transient relocation of NK-cells and B-cells into peripheral blood, which could be harnessed to enhance the efficacy of rituximab in CLL by relocating both target and effector cells together with rituximab in blood. In this pilot study, n = 20 patients with treatment-naïve CLL completed a bout of cycling 15 % above anaerobic threshold for ∼ 30-minutes, with blood samples collected pre-, immediately post-, and 1-hour post-exercise. Flow cytometry revealed that exercise evoked a 254 % increase in effector (CD3−CD56+CD16+) NK-cells in blood, and a 67 % increase in CD5+CD19+CD20+ CLL cells in blood (all p < 0.005). NK-cells were isolated from blood samples pre-, and immediately post-exercise and incubated with primary isolated CLL cells with or without the presence of rituximab to determine specific lysis using a calcein-release assay. Rituximab-mediated cell lysis increased by 129 % following exercise (p < 0.001). Direct NK-cell lysis of CLL cells – independent of rituximab – was unchanged following exercise (p = 0.25). We conclude that exercise improved the efficacy of rituximab-mediated ADCC against autologous CLL cells ex vivo and propose that exercise should be explored as a means of enhancing clinical responses in patients receiving anti-CD20 immunotherapy.

Assessment of Immunomodulatory Activity of AP-Bio® (KalmCold®), a Standardized Extract of Andrographis paniculata Using in vivo and ex vivo Models

Background: Andrographis paniculata (Burm. f.) Nees is a well-recognized medicinal plant known for its benefits against a multitude of ailments. The intent of the present study was to evaluate the effect of a standardized extract of A. paniculata on innate immunity. Materials and Methods: Phagocytic activity was measured in terms of phagocytic index using carbon clearance methodology in mice. In another experiment, NK cells (effector cells) were isolated from the mouse spleen after the dosing period, and NK cells-mediated lysis of target cells (YAC-1 cells) were determined using an MTT assay. Results: The phagocytic index and NK cell activity were found to be significantly ( p &lt; 0.05) different in the treated group compared to the control group in the tested animal models at a dose of 41 mg/kg. Conclusion: The results suggest the potential of A. paniculata to enhance innate immunity.

Metabolic Regulation of Natural Killer Cells

Natural Killer cells, known as NK cells act crucially in protection of anti-tumor and anti-virus activities as innate lymphocytes. Due to its unique characteristics such as recognizing and attacking stressed cells independently, and bridge connection function between innate immunity and adaptive immunity, it possesses profound potential and prospect in immunotherapy. However, due to resistance existing in combination of therapies and undeclared metabolism pathways, its application in clinical trials has been underestimated. Metabolic configurations are adopted to support functions, which is dynamic when immune cells experience the procedure of metabolic reprogramming in responses. In order to support anti-tumor functions, NK cells up regulate both glycolysis and OXPHOS, leading to the alternative of energy metabolism structure and ATP relief upon activation with pro-inflammatory cytokines. After activation, what exactly determines phenotypes and destiny of NK cells is also being considered as the classification standard of receptors distribution is found both vague and not universally applicable. Additionally, author focus on metabolic factors in solid cancer treating, which are highly relative to tumor microenvironment (TME). TME provides many molecules for the prevention of potential effector function of normal cells (especially immune cells) and protection of tumor. For example, substances such as TGF-β are capable to not only downregulate NK cell cytotoxicity and cytokine secretion but also reduce the extent of metabolism and proliferation, and also induce effector NK cells to increase the production of ILC1-like characteristics. This review will discuss NK cells’ metabolic foundation to realize NK cell effector functions and analyze the relationship between phenotypes, NK cell fates and metabolism. Also, basing on impaired functions, immune suppression and resistance of joint therapies, the author will discuss different pathways and possible treating targets and therapies in order to boost cancer treatment progress such as adoptive NK cell therapy, bio- or tri- engager therapy and CAR-NK therapy.

Cyclooxygenase-2 Blockade Is Crucial to Restore Natural Killer Cell Activity before Anti-CTLA-4 Therapy against High-Grade Serous Ovarian Cancer.

Chronic inflammation influences the tumor immune microenvironment (TIME) in high-grade serous ovarian cancer (HGSOC). Specifically, cyclooxygenase-2 (COX-2) overexpression promotes cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) expression. Notably, elevated COX-2 levels in the TIME have been associated with reduced response to anti-CTLA-4 immunotherapy. However, the precise impact of COX-2, encoded by PTGS2, on the immune profile remains unknown. To address this, we performed an integrated bioinformatics analysis using data from the HGSOC cohorts (TCGA-OV, n = 368; Australian cohort AOCS, n = 80; GSE26193, n = 62; and GSE30161, n = 45). Employing Gene Set Variation Analysis (GSVA), MIXTURE and Ecotyper cell deconvolution algorithms, we concluded that COX-2 was linked to immune cell ecosystems associated with shorter survival, cell dysfunction and lower NK cell effector cytotoxicity capacity. Next, we validated these results by characterizing circulating NK cells from HGSOC patients through flow cytometry and cytotoxic assays while undergoing COX-2 and CTLA-4 blockade. The blockade of COX-2 improved the cytotoxic capacity of NK cells against HGSOC cell lines. Our findings underscore the relevance of COX-2 in shaping the TIME and suggest its potential as a prognostic indicator and therapeutic target. Increased COX-2 expression may hamper the effectivity of immunotherapies that require NK cell effector function. These results provide a foundation for experimental validation and clinical trials investigating combined therapies targeting COX-2 and CTLA-4 in HGSOC.

Determinants of Response to Anti CD-19 CAR-T Cells for Diffuse Large B-Cell Lymphoma in Pre-Treatment Peripheral Blood Mononuclear Cells Using Single-Cell RNA-Seq

Background: Chimeric antigen receptor T (CAR-T) cell therapy has become the standard of care in patients with relapsed/refractory diffuse large cell lymphoma (R/R DLBCL), providing durable remission in 40% of patients. Lack of response is likely to be attributed to inter- and intra-patient variability, including PBMC heterogeneity and apheresis material composition, CAR-T infusion product, in-vivo expansion and activity of CAR-T cells and the development of tumor-intrinsic mechanisms. Current methods for evaluating CAR-T cell activation and potency have limited predictive value for clinical outcomes. To address this challenge, we performed single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells (PBMCs) obtained from patients with R/R LBCL patients at the time of apheresis for the manufacturing of anti-CD19 CAR-T cell therapy. Methods: Between 10/2020 and 03/2022, 31 patients who underwent lymphopheresis were enrolled. Samples were obtained - 1) At day of lymphopheresis from peripheral blood; 2) On the day of infusion of CAR-T from the product; and 3) On day +7 after infusion from peripheral blood. All patients had day +30 PET-CT. In addition, PBMCs samples from healthy donors were used as control to analyze baseline characteristics compared to the DLBCL patients. PBMCs from patients of healthy donors were purified from frozen blood samples by density gradient separation, stained using human CD45 antibody and loaded onto a 10x Chromium system. libraries were generated using the 10X Genomics Chromium Single Cell 3' Kit. The data was processed and analyzed using the Seurat R package. The study was approved by the local Ethic committee. Results: Patient characteristics: 31 RR DLBCL patients (42% females; median age 72, range 47-81 years), all treated with CAR-T cells therapy as third line of therapy, participated in the study. All patients underwent lymphopheresis, followed by CAR-T production. Disease status at lymphodepletion was complete remission (CR, n=4, 13%), partial remission (n=6, 19%), and progressive disease (n=21, 68%) and patients received either tisagenlecleucel (n=20, 65%) or axicabtagene ciloleucel (n=11, 35%) . PET scan performed on day 30 post treatment revealed that 68% and 32% obtained CR, and PD, respectively. scRNA analysis revealed differences in PBMC composition between healthy donors and LBCL patients (Figure 1A), with lower levels of naïve and memory T cells and elevated levels of activated monocytes in LBCL patients, suggesting a shift towards an inflamed and pre-dysfunctional immune state. Categorization of LBCL patients into responders (PR/CR on day +30 PET-CT) and non-responders (PD on day +30 PET-CT) revealed differences in immune cell subsets between responders and non-responders (Figure 2A), with enriched inflammation-related pathways in non-responders, In contrast, responders exhibited a distinct healthy-like immune profiles, particularly high levels of naive T cells, similar to that obtained in their age matched healthy controls. Of note, non-responders showed alterations in immune cell subsets, including increased levels of T regulatory cells and effector NK cells. Furthermore, non-responders demonstrated a prominent inflammatory immune profile, characterized by gene pathways related to inflammation and activation, such as type I and III IFN-G, and TNFb response (Figure 1B). Notably, an IFN-G score was significantly higher in non-responder's monocytes subpopulations, compared to responders. Conclusions: These findings indicate that the success of CAR-T therapy could be determined by the molecular characteristics and subpopulation distribution of each patient's PBMC. The diverse immune profiles of DLBCL patients might impact the effectiveness of their immune cells in generating successful CAR-T products or providing a conducive environment for CAR T cells to combat cancer. Furthermore, these findings emphasize the potential of scRNA-seq in evaluating PBMC from CAR-T patients prior to treatment, allowing the potential calculation of an “immune potency score” associated with the probability of a positive outcome from CAR-T treatment of DLBCL patients. This score could potentially be used by oncologists in decision-making processes to determine the appropriate candidates for CAR-T therapy.

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.

Characterizing hepatocellular carcinoma stem markers and their corresponding susceptibility to NK-cell based immunotherapy.

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and is the fourth-leading cause of all cancer-related deaths around the world. Liver transplantation, surgery, and local ablation are curative therapies for early-stage HCC. However, post-treatment outcomes can vary based on histopathologic stage. Poorly-differentiated HCC are associated with higher rates of tumor progression and lower overall survival compared to well-differentiated HCC after therapy. In this study, we aimed to characterize the cancer stem cell (CSC) profile of histopathologically-proven well and poorly-differentiated HCCs in an in-vitro environment. We characterized the stem-like profile of each type of HCC based on their surface markers and susceptibility to NK cell-mediated cytotoxicity. Flow cytometry was used to quantify differential expression of MHC-class I, CD54, and CD44 between well- and poorly-differentiated HCCs. Primary untreated NK cells, IL-2 stimulated primary NK cells, and supercharged (sNK) cell-mediated cytotoxicity was assessed against well- and poorly-differentiated HCCs. IFN-γ supernatant from each respective NK cell experimental arm was also used to induce differentiation of HCCs. Finally, we characterized the temporal NK effector cell cytotoxicity using real-time quantitative analysis of imaging and impedance (eSight study). Poorly-differentiated HCCs demonstrated low surface expression of MHC-class I and CD54, and high expression of CD44. Treatment of NK cells secreted IFN-γ or IFN-γ cytokine induced differentiation in HCCs. Poorly-differentiated HCCs in comparison to well-differentiated HCC were more susceptible to NK cell-mediated cytotoxicity in primary NK cells, IL-2 stimulated primary NK cells, and sNK cells. sNK cells induced significantly higher cytotoxicity against well-differentiated HCCs in comparison to untreated or IL-2-stimulated primary NK cells. These findings were recapitulated with real-time quantitative imaging analysis. Poorly-differentiated HCCs were found to have surface marker patterns of CSCs, making them highly susceptible to NK cell-based immunotherapy. NK-cell based therapy can potentially be leveraged as a neoadjuvant or adjuvant therapy in poorly-differentiated HCCs. Supercharged NK cells, which can be rapidly expanded to therapeutic levels, are uniquely capable of lysing both poorly- and well-differentiated HCCs. This finding suggests that sNK cells not only exhibit enhanced features against NK cells' targets but also are capable of activating T cells to induce cytotoxicity against well-differentiated HCCs with high expression of MHC class I.

Dietary supplementation with American ginseng dietary fiber ameliorates intestinal mucosal barrier injury in immunosuppressed mice

Dietary fiber is an important component of healthy eating patterns. Although American ginseng (Panax quiquefolium L.) is often used to improve body immunity, less attention has been paid to American ginseng dietary fiber (AGDF) in this regard. The aim of this study was to investigate the protective effect of AGDF on intestinal mucosal barrier injury induced by cyclophosphamide (CTX) in immunosuppressed mice and the underlying mechanism. The results showed that AGDF could increase immune organ index and enhance immunity of immunosuppressed mice, such as DTH response, lymphocyte transformation and proliferation and NK effector cell activity. At the same time, AGDF could restore the proportion of CD4+/CD8+ T lymphocytes induced by CTX to different extents, and promote the secretion of immunoglobulin IgG. More importantly, AGDF could up-regulate the contents of TNF-α, IFN-γ, IL-6 and IL-1β in serum and intestine of immunosuppressed mice, promote the secretion of cytokines and regulate the homeostasis balance between Th1/Th2 cytokines. It also upregulated the expression of tight junction proteins occludin, claudin-1 and ZO-1, and alleviated the degree of CTX-induced damage to the intestinal mucosal barrier. Meanwhile, AGDF could reduce intestinal epithelial cell apoptosis by activating TLR4/NF-κB signaling pathway, improving the phosphorylation of JNK and p38 signaling molecules, which may be the potential mechanism by which AGDF ameliorates intestinal mucosal injury in immunosuppressed mice. Therefore, AGDF may be used as a dietary supplement to prevent and treat intestinal mucosal barrier injury caused by CTX.

Analysis of the mechanisms regulating soluble PD-1 production and function in human NK cells.

NK cells represent important effectors that play a major role in innate defences against pathogens and display potent cytolytic activity against tumor cells. An array of surface receptors finely regulate their function and inhibitory checkpoints, such as PD-1, can dampen the immune response inducing an immunosuppressive state. Indeed, PD-1 expression in human NK cells correlated with impaired effector function and tumor immune evasion. Importantly, blockade of the PD-1/PD-L1 axis has been shown to reverse NK cell exhaustion and increase their cytotoxicity. Recently, soluble counterparts of checkpoint receptors, such as soluble PD-1 (sPD-1), are rising high interest due to their biological activity and ability to modulate immune responses. It has been widely demonstrated that sPD-1 can modulate T cell effector functions and tumor growth. Tumor-infiltrating T cells are considered the main source of circulating sPD-1. In addition, recently, also stimulated macrophages have been demonstrated to release sPD-1. However, no data are present on the role of sPD-1 in the context of other innate immune cell subsets and therefore this study is aimed to unveil the effect of sPD-1 on human NK cell function. We produced the recombinant sPD-1 protein and demonstrated that it binds PD-L1 and that its presence results in increased NK cell cytotoxicity. Notably, we also identified a pathway regulating endogenous sPD-1 synthesis and release in human NK cells. Secreted endogenous sPD-1, retained its biological function and could modulate NK cell effector function. Overall, these data reveal a pivotal role of sPD-1 in regulating NK-mediated innate immune responses.