Immunometabolic Dysfunction of Natural Killer Cells Mediated by the Hypoxia-CD73 Axis in Solid Tumors

Antitumor activity of genetically engineered NK-cells in non-hematological solid tumor: a comprehensive review

Recent advancements in genetic engineering have made it possible to modify Natural Killer (NK) cells to enhance their ability to fight against various cancers, including solid tumors. This comprehensive overview discusses the current status of genetically engineered chimeric antigen receptor NK-cell therapies and their potential for treating solid tumors. We explore the inherent characteristics of NK cells and their role in immune regulation and tumor surveillance. Moreover, we examine the strategies used to genetically engineer NK cells in terms of efficacy, safety profile, and potential clinical applications. Our investigation suggests CAR-NK cells can effectively target and regress non-hematological malignancies, demonstrating enhanced antitumor efficacy. This implies excellent promise for treating tumors using genetically modified NK cells. Notably, NK cells exhibit low graft versus host disease (GvHD) potential and rarely induce significant toxicities, making them an ideal platform for CAR engineering. The adoptive transfer of allogeneic NK cells into patients further emphasizes the versatility of NK cells for various applications. We also address challenges and limitations associated with the clinical translation of genetically engineered NK-cell therapies, such as off-target effects, immune escape mechanisms, and manufacturing scalability. We provide strategies to overcome these obstacles through combination therapies and delivery optimization. Overall, we believe this review contributes to advancing NK-cell-based immunotherapy as a promising approach for cancer treatment by elucidating the underlying mechanisms, evaluating preclinical and clinical evidence, and addressing remaining challenges.

Nanocatalysts for modulating antitumor immunity: fabrication, mechanisms and applications

Immunotherapy harnesses the inherent immune system in the body to generate systemic antitumor immunity, offering a promising modality for defending against cancer. However, tumor immunosuppression and evasion seriously restrict the immune response rates in clinical settings. Catalytic nanomedicines can transform tumoral substances/metabolites into therapeutic products in situ, offering unique advantages in antitumor immunotherapy. Through catalytic reactions, both tumor eradication and immune regulation can be simultaneously achieved, favoring the development of systemic antitumor immunity. In recent years, with advancements in catalytic chemistry and nanotechnology, catalytic nanomedicines based on nanozymes, photocatalysts, sonocatalysts, Fenton catalysts, electrocatalysts, piezocatalysts, thermocatalysts and radiocatalysts have been rapidly developed with vast applications in cancer immunotherapy. This review provides an introduction to the fabrication of catalytic nanomedicines with an emphasis on their structures and engineering strategies. Furthermore, the catalytic substrates and state-of-the-art applications of nanocatalysts in cancer immunotherapy have also been outlined and discussed. The relationships between nanostructures and immune regulating performance of catalytic nanomedicines are highlighted to provide a deep understanding of their working mechanisms in the tumor microenvironment. Finally, the challenges and development trends are revealed, aiming to provide new insights for the future development of nanocatalysts in catalytic immunotherapy.

synNotch-programmed iPSC-derived NK cells usurp TIGIT and CD73 activities for glioblastoma therapy

Severe heterogeneity within glioblastoma has spurred the notion that disrupting the interplay between multiple elements on immunosuppression is at the core of meaningful anti-tumor responses. T cell immunoreceptor with Ig and ITIM domains (TIGIT) and its glioblastoma-associated antigen, CD155, form a highly immunosuppressive axis in glioblastoma and other solid tumors, yet targeting of TIGIT, a functionally heterogeneous receptor on tumor-infiltrating immune cells, has largely been ineffective as monotherapy, suggesting that disruption of its inhibitory network might be necessary for measurable responses. It is within this context that we show that the usurpation of the TIGIT - CD155 axis via engineered synNotch-mediated activation of induced pluripotent stem cell-derived natural killer (NK) cells promotes transcription factor-mediated activation of a downstream signaling cascade that results in the controlled, localized blockade of CD73 to disrupt purinergic activity otherwise resulting in the production and accumulation of immunosuppressive extracellular adenosine. Such "decoy" receptor engages CD155 binding to TIGIT, but tilts inhibitory TIGIT/CD155 interactions toward activation via downstream synNotch signaling. Usurping activities of TIGIT and CD73 promotes the function of adoptively transferred NK cells into intracranial patient-derived models of glioblastoma and enhances their natural cytolytic functions against this tumor to result in complete tumor eradication. In addition, targeting both receptors, in turn, reprograms the glioblastoma microenvironment via the recruitment of T cells and the downregulation of M2 macrophages. This study demonstrates that TIGIT/CD155 and CD73 are targetable receptor partners in glioblastoma. Our data show that synNotch-engineered pluripotent stem cell-derived NK cells are not only effective mediators of anti-glioblastoma responses within the setting of CD73 and TIGIT/CD155 co-targeting, but represent a powerful allogeneic treatment option for this tumor.

Associations between HIFs and tumor immune checkpoints: mechanism and therapy

Hypoxia, which activates a variety of signaling pathways to enhance tumor cell growth and metabolism, is among the primary features of tumor cells. Hypoxia-inducible factors (HIFs) have a substantial impact on a variety of facets of tumor biology, such as epithelial-mesenchymal transition, metabolic reprogramming, angiogenesis, and improved radiation resistance. HIFs induce hypoxia-adaptive responses in tumor cells. Many academics have presented preclinical and clinical research targeting HIFs in tumor therapy, highlighting the potential applicability of targeted HIFs. In recent years, the discovery of numerous pharmacological drugs targeting the regulatory mechanisms of HIFs has garnered substantial attention. Additionally, HIF inhibitors have attained positive results when used in conjunction with traditional oncology radiation and/or chemotherapy, as well as with the very promising addition of tumor immunotherapy. Immune checkpoint inhibitors (CPIs), which are employed in a range of cancer treatments over the past decades, are essential in tumor immunotherapy. Nevertheless, the use of immunotherapy has been severely hampered by tumor resistance and treatment-related toxicity. According to research, HIF inhibitors paired with CPIs may be game changers for multiple malignancies, decreasing malignant cell plasticity and cancer therapy resistance, among other things, and opening up substantial new pathways for immunotherapy drug development. The structure, activation mechanisms, and pharmacological sites of action of the HIF family are briefly reviewed in this work. This review further explores the interactions between HIF inhibitors and other tumor immunotherapy components and covers the potential clinical use of HIF inhibitors in combination with CPIs.

Hypoxia as a potential inducer of immune tolerance, tumor plasticity and a driver of tumor mutational burden: Impact on cancer immunotherapy

In cancer patients, immune cells are often functionally compromised due to the immunosuppressive features of the tumor microenvironment (TME) which contribute to the failures in cancer therapies. Clinical and experimental evidence indicates that developing tumors adapt to the immunological environment and create a local microenvironment that impairs immune function by inducing immune tolerance and invasion. In this context, microenvironmental hypoxia, which is an established hallmark of solid tumors, significantly contributes to tumor aggressiveness and therapy resistance through the induction of tumor plasticity/heterogeneity and, more importantly, through the differentiation and expansion of immune-suppressive stromal cells. We and others have provided evidence indicating that hypoxia also drives genomic instability in cancer cells and interferes with DNA damage response and repair suggesting that hypoxia could be a potential driver of tumor mutational burden. Here, we reviewed the current knowledge on how hypoxic stress in the TME impacts tumor angiogenesis, heterogeneity, plasticity, and immune resistance, with a special interest in tumor immunogenicity and hypoxia targeting. An integrated understanding of the complexity of the effect of hypoxia on the immune and microenvironmental components could lead to the identification of better adapted and more effective combinational strategies in cancer immunotherapy. Clearly, the discovery and validation of therapeutic targets derived from the hypoxic tumor microenvironment is of major importance and the identification of critical hypoxia-associated pathways could generate targets that are undeniably attractive for combined cancer immunotherapy approaches.

The role of natural killer cell activity as a milestone in oncologic outcome after curative resection of pancreatic adenocarcinoma

BACKGROUND

The objective of this study was to investigate differences in oncologic outcomes of patients with pancreas cancer according to natural killer cell activity (NKA).

METHODS

A total of 118 patients who underwent curative resection for primary pancreas cancer in two hospitals were analyzed. NKA change pattern was analyzed. Difference in disease-free survival or overall survival was investigated by dividing subjects into two groups based on a normal NKA value for each period.

RESULTS

NKA value decreased after surgery compared to the value measured at admission. It recovered to normal levels at 5 weeks postoperatively. The low NKA (less than 250 pg/mL) group at admission, 5 weeks postoperatively, and before 1st chemotherapy had significantly poorer disease-free survival than the normal NKA group. In multivariate analysis, NKA values less than 250 pg/mL at admission (odds ratio = 2.267, p = 0.023) and N 1 or N2 category (odds ratio = 2.478, p = 0.023) were significant factors associated with recurrence after curative resection.

CONCLUSIONS

NKA in patients with pancreatic cancer demonstrated noticeable changes after surgery. Immunologically predisposed patients with a low NKA value had a high risk of early recurrence and a poor prognosis, although pancreatic cancer was surgically removed.

Immunomodulatory properties of CD38 antibodies and their effect on anticancer efficacy in multiple myeloma

BACKGROUND

CD38 has been established as an important therapeutic target for multiple myeloma (MM), for which two CD38 antibodies are currently approved-daratumumab and isatuximab. CD38 is an ectoenzyme that degrades NAD and its precursors and is involved in the production of adenosine and other metabolites.

AIM

Among the various mechanisms by which CD38 antibodies can induce MM cell death is immunomodulation, including multiple pathways for CD38-mediated T-cell activation. Patients who respond to anti-CD38 targeting treatment experience more marked changes in T-cell expansion, activity, and clonality than nonresponders.

IMPLICATIONS

Resistance mechanisms that undermine the immunomodulatory effects of CD38-targeting therapies can be tumor intrinsic, such as the downregulation of CD38 surface expression and expression of complement inhibitor proteins, and immune microenvironment-related, such as changes to the natural killer (NK) cell numbers and function in the bone marrow niche. There are numerous strategies to overcome this resistance, which include identifying and targeting other therapeutic targets involved in, for example, adenosine production, the activation of NK cells or monocytes through immunomodulatory drugs and their combination with elotuzumab, or with bispecific T-cell engagers.

Remodeled tumor immune microenvironment (TIME) parade via natural killer cells reprogramming in breast cancer

Breast cancer (BC) is the main cause of cancer-related mortality among women globally. Despite substantial advances in the identification and management of primary tumors, traditional therapies including surgery, chemotherapy, and radiation cannot completely eliminate the danger of relapse and metastatic illness. Metastasis is controlled by microenvironmental and systemic mechanisms, including immunosurveillance. This led to the evolvement of immunotherapies that has gained much attention in the recent years for cancer treatment directed to the innate immune system. The long forgotten innate immune cells known as natural killer (NK) cells have emerged as novel targets for more effective therapeutics for BC. Normally, NK cells has the capacity to identify and eradicate tumor cells either directly or by releasing cytotoxic granules, chemokines and proinflammatory cytokines. Yet, NK cells are exposed to inhibitory signals by cancer cells, which causes them to become dysfunctional in the immunosuppressive tumor microenvironment (TME) in BC, supporting tumor escape and spread. Potential mechanisms of NK cell dysfunction in BC metastasis have been recently identified. Understanding these immunologic pathways driving BC metastasis will lead to improvements in the current immunotherapeutic strategies. In the current review, we highlight how BC evades immunosurveillance by rendering NK cells dysfunctional and we shed the light on novel NK cell- directed therapies.

FBP1 is a potential prognostic biomarker and correlated with tumor immunosuppressive microenvironment in glioblastoma

Hypoxia has been shown to contribute to tumor immunosuppressive microenvironment and is an effective prognostic indicator. This study aimed to screen prognostic hypoxia-related genes (HRGs) in glioblastoma and investigate the association between HRGs and tumor immunosuppressive microenvironment. The glioblastoma-related mRNA data were collected from TCGA, GEO, and CGGA databases. Totally 200 HRGs were obtained from the GSEA website. The prognostic HRGs were screened by univariate Cox regression analysis. Somatic mutation data of glioblastoma from TCGA was visualized using the "maftools" of R package. Immune cell infiltration proportions were calculated by CIBERSORT. The TISIDB online tool was applied to analyze the relationship between HRGs and immunoinhibitors as well as the HRG expression in different glioblastoma immune and molecular subtypes. Hub gene's mRNA and protein levels in cell lines were determined by qRT-PCR and western blot, respectively. The effects of hub gene knockdown on cell viability and migration ability were evaluated employing CCK8 and wound healing assays. The univariate Cox regression showed that high level of FBP1 (fructose-1,6-bisphosphatase 1) was a poor prognostic biomarker, and FBP1 was mainly expressed in lymphocyte depleted immune subtype of glioblastoma. High FBP1 mRNA and protein levels have been successfully validated in vitro. The somatic mutation analysis suggested that TP53 mutation rate was the highest in the high FBP1 glioblastoma group, while EGFR mutation rate was the highest in the low FBP1 glioblastoma group. In the high FBP1 group, the infiltration proportions and types of immune cells were less, dominated by macrophages M2, and the expression of CTLA4, LAG3, TIGIT, PDL1, and PDL2 was significantly upregulated. The expression of FBP1 was positively correlated with several immunoinhibitors, such as IL-10 and TGFβ-1. In conclusion, we demonstrated that FBP1 could serve as a prognostic biomarker for glioblastoma. The immune microenvironment in the high FBP1 group might be suppressed by up-regulating immune checkpoints and immunoinhibitors.

Manganese facilitated cGAS-STING-IFNI pathway activation induced by ionizing radiation in glioma cells

PURPOSE

After irradiation, double-stranded DNA leaked into the cytoplasm activates the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, leading to the production of type I interferon (IFNI). In this study, we sought to probe the effect of ionizing radiation on activity of cGAS-STING-IFNI pathway in normoxic or hypoxic glioma cells and explore a more effective method to activate the signaling pathway, thereby activating the anti-tumor immune response and improving the therapeutic effect of radiotherapy for glioma.

MATERIALS AND METHODS

Human glioma cells U251 and T98G cultured in normoxia or hypoxia (1% O2) were irradiated with different doses of X-ray. The relative expressions of cGAS, IFN-I stimulated genes (ISGs), and three-prime repair exonuclease 1 (TREX1) were detected by qPCR. The expression levels of interferon regulatory factor 3 (IRF3) and p-IRF3 proteins were detected by Western blot. The production of cGAMP and IFN-β in the supernatant was detected by ELISA assay. U251 and T98G cell lines with stable knockdown of TREX1 were established after transfection with lentivirus vectors. EdU cell proliferation assay was used to screen suitable metal ions concentrations. The phagocytosis of DCs was observed by immunofluorescence microscope. The phenotype of DCs was detected by flow cytometry. The migration ability of DCs was detected by a transwell experiment.

RESULTS

We found that cytosolic dsDNA, 2'3'-cGAMP, cGAS and ISGs expression, and IFN-β in cell supernatant were all increased with the doses of X-ray in the range of 0-16 Gy in normoxic glioma cells. Nevertheless, hypoxia significantly inhibited the radiation-induced dose-dependent activation of cGAS-STING-IFNI pathway. Furthermore, manganese (II) ion (Mn2+) significantly improved cGAS-STING-IFNI pathway activation induced by X-ray in both normoxic and hypoxic glioma cells, thereby promoting the maturation and migration of DCs.

CONCLUSIONS

The responses of cGAS-STING-IFNI pathway to ionizing radiation were mainly investigated under normoxic condition, but the experiments described here indicated that hypoxia could hinder the pathway activation. However, Mn2+ showed radiosensitizing effects on the pathway under either normoxic or hypoxic conditions demonstrating its potential as a radiosensitizer for glioma through activating an anti-tumor immune response.

PET/MRI and Bioluminescent Imaging Identify Hypoxia as a Cause of Programmed Cell Death Ligand 1 Image Heterogeneity

Purpose To examine the association between hypoxia and programmed cell death ligand 1 (PD-L1) expression using bioluminescence imaging (BLI) and PET/MRI in a syngeneic mouse model of triple-negative breast cancer (TNBC). Materials and Methods PET/MRI and optical imaging were used to determine the role of hypoxia in altering PD-L1 expression using a syngeneic TNBC model engineered to express luciferase under hypoxia. Results Imaging showed a close spatial association between areas of hypoxia and increased PD-L1 expression in the syngeneic murine (4T1) tumor model. Mouse and human TNBC cells exposed to hypoxia exhibited a significant increase in PD-L1 expression, consistent with the in vivo imaging data. The role of hypoxia in increasing PD-L1 expression was further confirmed by using The Cancer Genome Atlas analyses of different human TNBCs. Conclusion These results have identified the potential role of hypoxia in contributing to PD-L1 heterogeneity in tumors by increasing cancer cell PD-L1 expression. Keywords: Hypoxia, PD-L1, Triple-Negative Breast Cancer, PET/MRI, Bioluminescence Imaging Supplemental material is available for this article. © RSNA, 2023.

Inhibitors of the CD73-adenosinergic checkpoint as promising combinatory agents for conventional and advanced cancer immunotherapy

The cell surface enzyme CD73 is increasingly appreciated as a pivotal non-redundant immune checkpoint (IC) in addition to PD-1/PD-L1 and CTLA-4. CD73 produces extracellular adenosine (eADO), which not only inhibits antitumor T cell activity via the adenosine receptor (AR) A_2AR, but also enhances the immune inhibitory function of cancer-associated fibroblasts and myeloid cells via A_2BR. Preclinical studies show that inhibition of the CD73-adenosinergic pathway in experimental models of many solid tumors either as a monotherapy or, more effectively, in combination with PD-1/PD-L1 or CTLA-4 IC blockades, improves antitumor immunity and tumor control. Consequently, approximately 50 ongoing phase I/II clinical trials targeting the CD73-adenosinergic IC are currently listed on https://clinicaltrials.gov. Most of the listed trials employ CD73 inhibitors or anti-CD73 antibodies alone, in combination with A_2AR antagonists, and/or with PD-1/PD-L1 blockade. Recent evidence suggests that the distribution of CD73, A_2AR and A_2BR in tumor microenvironments (TME) is heterogeneous, and this distribution affects CD73-adenosinergic IC function. The new insights have implications for the optimally effective, carefully tailored approaches to therapeutic targeting of this essential IC. In the mini-review, we briefly discuss the cellular and molecular mechanisms of CD73/eADO-mediated immunosuppression during tumor progression and therapy in the spatial context of the TME. We include preclinical data regarding therapeutic CD73-eADO blockade in tumor models as well as available clinical data from completed trials that targeted CD73-adenosinergic IC with or without PD-1/PD-L1 inhibitors and discuss factors that are potentially important for optimal therapeutic outcomes in cancer patients.

Comparative Evaluation of Synthetic Cytokines for Enhancing Production and Performance of NK92 Cell-Based Therapies

Off-the shelf immune cell therapies are potentially curative and may offer cost and manufacturing advantages over autologous products, but further development is needed. The NK92 cell line has a natural killer-like phenotype, has efficacy in cancer clinical trials, and is safe after irradiation. However, NK92 cells lose activity post-injection, limiting efficacy. This may be addressed by engineering NK92 cells to express stimulatory factors, and comparative analysis is needed. Thus, we systematically explored the expression of synthetic cytokines for enhancing NK92 cell production and performance. All synthetic cytokines evaluated (membrane-bound IL2 and IL15, and engineered versions of Neoleukin-2/15, IL15, IL12, and decoy resistant IL18) enhanced NK92 cell cytotoxicity. Engineered cells were preferentially expanded by expressing membrane-bound but not soluble synthetic cytokines, without compromising the radiosensitivity required for safety. Some membrane-bound cytokines conferred cell-contact independent paracrine activity, partly attributable to extracellular vesicles. Finally, we characterized interactions within consortia of differently engineered NK92 cells.

CD39 (ENTPD1) in tumors: a potential therapeutic target and prognostic biomarker

As a regulator of the dynamic balance between immune-activated extracellular ATP and immunosuppressive adenosine, CD39 ectonucleotidase impairs the ability of immune cells to exert anticancer immunity and plays an important role in the immune escape of tumor cells within the tumor microenvironment. In addition, CD39 has been studied in cancer patients to evaluate the prognosis, the efficacy of immunotherapy (e.g., PD-1 blockade) and the prediction of recurrence. This article reviews the importance of CD39 in tumor immunology, summarizes the preclinical evidence on targeting CD39 to treat tumors and focuses on the potential of CD39 as a biomarker to evaluate the prognosis and the response to immune checkpoint inhibitors in tumors.

Immune gene patterns and characterization of the tumor immune microenvironment associated with cancer immunotherapy efficacy

Although immunotherapy has revolutionized cancer management, most patients do not derive benefits from it. Aiming to explore an appropriate strategy for immunotherapy efficacy prediction, we collected 6251 patients' transcriptome data from multicohort population and analyzed the data using a machine learning algorithm. In this study, we found that patients from three immune gene clusters had different overall survival when treated with immunotherapy (P < 0.001), and that these clusters had differential states of hypoxia scores and metabolism functions. The immune gene score showed good immunotherapy efficacy prediction (AUC was 0.737 at 20 months), which was well validated. The immune gene score, tumor mutation burden, and long non-coding RNA score were further combined to build a tumor immune microenvironment signature, which correlated more strongly with overall survival (AUC, 0.814 at 20 months) than when using a single variable. Thus, we recommend using the characterization of the tumor immune microenvironment associated with immunotherapy efficacy via a multi-omics analysis of cancer.

Nucleoside transporters and immunosuppressive adenosine signaling in the tumor microenvironment: Potential therapeutic opportunities

Adenosine compartmentalization has a profound impact on immune cell function by regulating adenosine localization and, therefore, extracellular signaling capabilities, which suppresses immune cell function in the tumor microenvironment. Nucleoside transporters, responsible for the translocation and cellular compartmentalization of hydrophilic adenosine, represent an understudied yet crucial component of adenosine disposition in the tumor microenvironment. In this review article, we will summarize what is known regarding nucleoside transporter's function within the purinome in relation to currently devised points of intervention (i.e., ectonucleotidases, adenosine receptors) for cancer immunotherapy, alterations in nucleoside transporter expression reported in cancer, and potential avenues for targeting of nucleoside transporters for the desired modulation of adenosine compartmentalization and action. Further, we put forward that nucleoside transporters are an unexplored therapeutic opportunity, and modulation of nucleoside transport processes could attenuate the pathogenic buildup of immunosuppressive adenosine in solid tumors, particularly those enriched with nucleoside transport proteins.

Adenosine 2A Receptor Activation Amplifies Ibrutinib Antiplatelet Effect; Implications in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia patients have an increased bleeding risk with the introduction of Bruton tyrosine kinase (BTK) inhibitors. BTK is a signaling effector downstream of the platelet GPVI receptor. Innate platelet dysfunction in CLL patients and the contribution of the leukemia microenvironment to the anti-platelet effect of BTK inhibitors are still not well defined. Herein, we investigated platelet function in stable, untreated CLL patients in comparison to age-matched healthy subjects as control. Secondly, we proposed a novel mechanism of platelet dysfunction via the adenosinergic pathway during BTK inhibitor therapy. Our data indicate that the nucleotidase that produces adenosine, CD73, was expressed on one-third of B-cells in CLL patients. Inhibition of CD73 improved platelet response to ADP in the blood of CLL patients ex vivo. Using healthy platelets, we show that adenosine 2A (A2A) receptor activation amplifies the anti-platelet effect of ibrutinib (10 nM). Ibrutinib plus an A2A agonist-but not ibrutinib as a single agent-significantly inhibited collagen (10 µg/mL)-induced platelet aggregation. Mechanistically, A2A activation attenuated collagen-mediated inhibition of p-VASP and synergized with ibrutinib to inhibit the phosphorylation of AKT, ERK and SYK kinases. This manuscript highlights the potential role of adenosine generated by the microenvironment in ibrutinib-associated bleeding in CLL patients.

Redox regulation of the immune response

The immune-inflammatory response is associated with increased nitro-oxidative stress. The aim of this mechanistic review is to examine: (a) the role of redox-sensitive transcription factors and enzymes, ROS/RNS production, and the activity of cellular antioxidants in the activation and performance of macrophages, dendritic cells, neutrophils, T-cells, B-cells, and natural killer cells; (b) the involvement of high-density lipoprotein (HDL), apolipoprotein A1 (ApoA1), paraoxonase-1 (PON1), and oxidized phospholipids in regulating the immune response; and (c) the detrimental effects of hypernitrosylation and chronic nitro-oxidative stress on the immune response. The redox changes during immune-inflammatory responses are orchestrated by the actions of nuclear factor-κB, HIF1α, the mechanistic target of rapamycin, the phosphatidylinositol 3-kinase/protein kinase B signaling pathway, mitogen-activated protein kinases, 5' AMP-activated protein kinase, and peroxisome proliferator-activated receptor. The performance and survival of individual immune cells is under redox control and depends on intracellular and extracellular levels of ROS/RNS. They are heavily influenced by cellular antioxidants including the glutathione and thioredoxin systems, nuclear factor erythroid 2-related factor 2, and the HDL/ApoA1/PON1 complex. Chronic nitro-oxidative stress and hypernitrosylation inhibit the activity of those antioxidant systems, the tricarboxylic acid cycle, mitochondrial functions, and the metabolism of immune cells. In conclusion, redox-associated mechanisms modulate metabolic reprogramming of immune cells, macrophage and T helper cell polarization, phagocytosis, production of pro- versus anti-inflammatory cytokines, immune training and tolerance, chemotaxis, pathogen sensing, antiviral and antibacterial effects, Toll-like receptor activity, and endotoxin tolerance.

CD39 - A bright target for cancer immunotherapy

The ATP-adenosine pathway functions as a key modulator of innate and adaptive immunity within the tumor microenvironment, and cancer immune evasion largely involves the generation of high amounts of immunosuppressive extracellular adenosine (eADO). Consequently, inhibition of eADO-generating enzymes and/or eADO receptors can effectively restore the antitumor immunity of multiple immune cells. With several clinical strategies currently being explored to modulating the eADO pathway in patients with cancer, recent clinical data with antagonists targeting CD73 and A_2A receptor have demonstrated a promising therapeutic potential in cancer. Recent findings reveal that the ectonucleotidase CD39, the limiting enzyme been viewed as "immunological switch", converts ATP-driven pro-inflammatory milieu to an anti-inflammatory state mediated by adenosine. Owing to its superior feature of CD39 antagonism that rely not only on preventing the accumulation of adenosine but also on the stabilization of extracellular ATP to restore antitumor immunity, several inhibitors and clinical trials based on CD39 are being evaluated. Consequently, there is currently a focus on understanding the role of CD39 in governing immunity and how therapeutic strategies targeting this pathway alter the antitumor potential. We herein review the impact of CD39 on tumor microenvironment with a focus on treatment preference. Additionally, we also discuss the implication for rational combination therapies, molecular regulation, as well as potential limitations.

NK Cell-Based Immunotherapy in Colorectal Cancer

Human Natural Killer (NK) cells are all round players in immunity thanks to their powerful and immediate response against transformed cells and the ability to modulate the subsequent adaptive immune response. The potential of immunotherapies based on NK cell involvement has been initially revealed in the hematological setting but has inspired the design of different immune tools to also be applied against solid tumors, including colorectal cancer (CRC). Indeed, despite cancer prevention screening plans, surgery, and chemotherapy strategies, CRC is one of the most widespread cancers and with the highest mortality rate. Therefore, further efficient and complementary immune-based therapies are in urgent need. In this review, we gathered the most recent advances in NK cell-based immunotherapies aimed at fighting CRC, in particular, the use of monoclonal antibodies targeting tumor-associated antigens (TAAs), immune checkpoint blockade, and adoptive NK cell therapy, including NK cells modified with chimeric antigen receptor (CAR-NK).

NK Cells Under Hypoxia: The Two Faces of Vascularization in Tumor and Pregnancy

Environmental conditions greatly shape the phenotype and function of immune cells. Specifically, hypoxic conditions that exist within tissues and organs have been reported to affect both the adaptive and the innate immune system. Natural killer (NK) cells belong to the innate immune system. They are among the first immune cells responding to infections and are involved in tumor surveillance. NK cells produce cytokines that shape other innate and adaptive immune cells, and they produce cytolytic molecules leading to target cell killing. Therefore, they are not only involved in steady state tissue homeostasis, but also in pathogen and tumor clearance. Hence, understanding the role of NK cells in pathological and physiological immune biology is an emerging field. To date, it remains incompletely understood how the tissue microenvironment shapes NK cell phenotype and function. In particular, the impact of low oxygen concentrations in tissues on NK cell reactivity has not been systematically dissected. Here, we present a comprehensive review focusing on two highly compelling hypoxic tissue environments, the tumor microenvironment (pathological) and the decidua (physiological) and compare their impact on NK cell reactivity.

Functional expression of CD73 on human natural killer cells

The production of adenosine by CD73 on cancer cells in the tumor microenvironment is a recognized immunosuppressive mechanism contributing to immune evasion in many solid tumors. While NK cells have been purported to overexpress CD73 under certain conditions, this phenomenon has remained elusive and unclear. We have found that while NK cells are able to upregulate expression of CD73 on their surface when exposed to CD73⁺ cancer cells, this upregulation is not universal, nor is it often substantial. Rather, our data point to the extent of CD73 expression on NK cells to be both cancer-specific and environmentally-driven, and largely limited in intensity. We found that NK cell overexpression of CD73 responds to the level of CD73 on cancer cells and is enhanced in hypoxia. Interestingly, human CD73⁺ NK cells appear hyperfunctional in vitro compared to CD73^- NK cells, suggesting that CD73 expression could be a bystander of NK cell activation. In addition, glioblastoma patient data show that tumor-infiltrating NK cells express CD73 variably, depending on donor, and present lower expression of CD16, alongside patient-specific changes in CEACAM1, CXCR3 and TIM-3, suggesting some functional changes in NK cell responses associated with expression of CD73 on NK cells in vivo. Taken together, our study is the first to show that while NK cells are largely resistant to the upregulation of CD73, CD73 expression is inducible on NK cells in response to CD73 on cancer cells, and these cells are associated with distinct functional signatures.

Killers on the loose: Immunotherapeutic strategies to improve NK cell-based therapy for cancer treatment

Natural killer (NK) cells are innate lymphocytes that control tumor progression by not only directly killing cancer cells, but also by regulating other immune cells, helping to orchestrate a coordinated anti-tumor response. However, despite the tremendous potential that this cell type has, the clinical results obtained from diverse NK cell-based immunotherapeutic strategies have been, until recent years, rather modest. The intrinsic regulatory mechanisms that are involved in the control of their activation as well as the multiple mechanisms that tumor cells have developed to escape NK cell-mediated cytotoxicity likely account for the unsatisfactory clinical outcomes. The current approaches to improve long-term NK cell function are centered on modulating different molecules involved in both the activation and inhibition of NK cells, and the latest data seems to advocate for combining strategies that target multiple aspects of NK cell regulation. In this review, we summarize the different strategies (such as engineered NK cells, CAR-NK, NK cell immune engagers) that are currently being used to take advantage of this potent and complex immune cell.

Understanding Molecular Mechanisms of Phenotype Switching and Crosstalk with TME to Reveal New Vulnerabilities of Melanoma

Melanoma cells are notorious for their high plasticity and ability to switch back and forth between various melanoma cell states, enabling the adaptation to sub-optimal conditions and therapeutics. This phenotypic plasticity, which has gained more attention in cancer research, is proposed as a new paradigm for melanoma progression. In this review, we provide a detailed and deep comprehensive recapitulation of the complex spectrum of phenotype switching in melanoma, the key regulator factors, the various and new melanoma states, and corresponding signatures. We also present an extensive description of the role of epigenetic modifications (chromatin remodeling, methylation, and activities of long non-coding RNAs/miRNAs) and metabolic rewiring in the dynamic switch. Furthermore, we elucidate the main role of the crosstalk between the tumor microenvironment (TME) and oxidative stress in the regulation of the phenotype switching. Finally, we discuss in detail several rational therapeutic approaches, such as exploiting phenotype-specific and metabolic vulnerabilities and targeting components and signals of the TME, to improve the response of melanoma patients to treatments.

Multifaceted Interplay between Hormones, Growth Factors and Hypoxia in the Tumor Microenvironment

Hormones and growth factors (GFs) are signaling molecules implicated in the regulation of a variety of cellular processes. They play important roles in both healthy and tumor cells, where they function by binding to specific receptors on target cells and activating downstream signaling cascades. The stages of tumor progression are influenced by hormones and GF signaling. Hypoxia, a hallmark of cancer progression, contributes to tumor plasticity and heterogeneity. Most solid tumors contain a hypoxic core due to rapid cellular proliferation that outgrows the blood supply. In these circumstances, hypoxia-inducible factors (HIFs) play a central role in the adaptation of tumor cells to their new environment, dramatically reshaping their transcriptional profile. HIF signaling is modulated by a variety of factors including hormones and GFs, which activate signaling pathways that enhance tumor growth and metastatic potential and impair responses to therapy. In this review, we summarize the role of hormones and GFs during cancer onset and progression with a particular focus on hypoxia and the interplay with HIF proteins. We also discuss how hypoxia influences the efficacy of cancer immunotherapy, considering that a hypoxic environment may act as a determinant of the immune-excluded phenotype and a major hindrance to the success of adoptive cell therapies.

Immunometabolism modulation, a new trick of edible and medicinal plants in cancer treatment

The edible and medicinal plants (EMPs) are becoming an abundant source for cancer prevention and treatment since the natural and healthy trend for modern human beings. Currently, there are more than one hundred species of EMPs widely used and listed by the national health commission of China, and most of them indicate immune or metabolic regulation potential in cancer treatment with numerous studies over the past two decades. In the present review, we focused on the metabolic influence in immunocytes and tumor microenvironment, including immune response, immunosuppressive factors and cancer cells, discussing the immunometabolic potential of EMPs in cancer treatment. There are more than five hundred references collected and analyzed through retrieving pharmacological studies deposited in PubMed by medical subject headings and the corresponding names derived from pharmacopoeia of China as a sole criterion. Finally, the immunometabolism modulation of EMPs was sketch out implying an immunometabolic control in cancer treatment.

A Hypoxia-Associated Prognostic Gene Signature Risk Model and Prognosis Predictors in Gliomas

Most solid tumours are hypoxic. Tumour cell proliferation and metabolism accelerate oxygen consumption. The low oxygen supply due to vascular abnormalisation and the high oxygen demand of tumour cells give rise to an imbalance, resulting in tumour hypoxia. Hypoxia alters cellular behaviour and is associated with extracellular matrix remodelling, enhanced tumour migration, and metastatic behaviour. In light of the foregoing, more research on the progressive and prognostic impacts of hypoxia on gliomas are crucial. In this study, we analysed the expression levels of 75 hypoxia-related genes in gliomas and found that a total of 26 genes were differentially expressed in The Cancer Genome Atlas (TCGA) database samples. We also constructed protein–protein interaction networks using the STRING database and Cytoscape. We obtained a total of 10 Hub genes using the MCC algorithm screening in the cytoHubba plugin. A prognostic risk model with seven gene signatures (PSMB6, PSMD9, UBB, PSMD12, PSMB10, PSMA5, and PSMD14) was constructed based on the 10 Hub genes using LASSO–Cox regression analysis. The model was verified to be highly accurate using subject work characteristic curves. The seven-gene signatures were then analysed by univariate and multivariate Cox. Notably, PSMB10, PSMD12, UBB, PSMA5, and PSMB6 were found to be independent prognostic predictive markers for glioma. In addition, PSMB6, PSMA5, UBB, and PSMD12 were lowly expressed, while PSMB10 was highly expressed, in the TCGA and GTEx integrated glioma samples and normal samples, which were verified through protein expression levels in the Human Protein Atlas database. This study found the prognostic predictive values of the hypoxia-related genes PSMB10, PSMD12, UBB, PSMA5, and PSMB6 for glioma and provided ideas and entry points for the progress of hypoxia-related glioma.

Hypoxia-Related Gene-Based Signature Can Evaluate the Tumor Immune Microenvironment and Predict the Prognosis of Colon Adenocarcinoma Patients

Background

Colon adenocarcinoma (COAD) is a common gastrointestinal tumor and often occurs in the left colon with a poor prognosis. The progression of COAD is closely related to the tumor microenvironment, especially the hypoxia. Currently, few studies have reported the correlation between hypoxia-related genes and the prognosis of COAD patients. Furthermore, we constructed a prognostic model using four hypoxia-related genes to predict the prognosis of COAD patients.

Methods

The mRNA expression profiles and corresponding clinicopathological data were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). The string online analysis tool was used to construct a protein–protein interaction network (PPI) of hypoxia-related genes. Kaplan–Meier curve was used to analyze the relationship of hypoxia risk score and the overall survival of COAD patients, and the receiver operating characteristic (ROC) curve was used to assess the reliability.

Results

We screened out four hypoxia genes, including TKTL1 (transketolase like 1), SLC2A3 (solute carrier family 2 member 3), ALDOB (aldolase, fructose-bisphosphate B) and ENO3 (enolase 3), which were used to construct a hypoxia risk model to predict the overall survival of COAD patients. Besides, we also found that the hypoxia risk score was correlated with the immunosuppression of tumor microenvironment.

Conclusion

The model we constructed with four survival-related hypoxia genes, including TKTL1, SLC2A3, ALDOB and ENO3, could be used to predict the overall survival of COAD patients with high stability.

Multispecific targeting of glioblastoma with tumor microenvironment-responsive multifunctional engineered NK cells

Tumor antigen heterogeneity, a severely immunosuppressive tumor microenvironment (TME) and lymphopenia resulting in inadequate immune intratumoral trafficking, have rendered glioblastoma (GBM) highly resistant to therapy. To address these obstacles, here we describe a unique, sophisticated combinatorial platform for GBM: a cooperative multifunctional immunotherapy based on genetically engineered human natural killer (NK) cells bearing multiple antitumor functions including local tumor responsiveness that addresses key drivers of GBM resistance to therapy: antigen escape, immunometabolic reprogramming of immune responses, and poor immune cell homing. We engineered dual-specific chimeric antigen receptor (CAR) NK cells to bear a third functional moiety that is activated in the GBM TME and addresses immunometabolic suppression of NK cell function: a tumor-specific, locally released antibody fragment which can inhibit the activity of CD73 independently of CAR signaling and decrease the local concentration of adenosine. The multifunctional human NK cells targeted patient-derived GBM xenografts, demonstrated local tumor site-specific activity in the tissue, and potently suppressed adenosine production. We also unveil a complex reorganization of the immunological profile of GBM induced by inhibiting autophagy. Pharmacologic impairment of the autophagic process not only sensitized GBM to antigenic targeting by NK cells but promoted a chemotactic profile favorable to NK infiltration. Taken together, our study demonstrates a promising NK cell-based combinatorial strategy that can target multiple clinically recognized mechanisms of GBM progression simultaneously.

A Redox-Responsive Nanovaccine Combined with A2A Receptor Antagonist for Cancer Immunotherapy

In situ vaccination can trigger an antitumor immune response. However, the therapeutic effect is still limited since the high expression of adenosine binding to G protein-coupled receptor A2AR induces an immunosuppressive effect. In this work, a new formulation is presented with the combination of a nanovaccine based on redox-responsive polymer micelles and A2AR antagonist SCH58261. The micelles simultaneously encapsulate immunogenic cell death (ICD) inducer doxorubicin (DOX) and adjuvant toll-like receptor 7 and 8 (TLR7/8) agonist R848, acting as the potent in situ vaccines. A high concentration of glutathione in tumor cells leads to the disintegration of these micelles, releasing DOX and R848 to mediate ICD, inducing the activation of dendritic cells and initiating an immune response. Meanwhile, A2AR antagonist SCH58261, a generation immune checkpoint blocker, inhibits the immunosuppressive adenosinergic pathway in the tumor microenvironment, activating natural killer (NK) cells and CD8⁺ T cells, and inhibiting the proliferation of regulatory T cells. Therefore, this formulation can trigger a robust systemic antitumor immune response.

Calcium Phosphate-Reinforced Metal-Organic Frameworks Regulate Adenosine-Mediated Immunosuppression

Long-term accumulation of adenosine (Ado) in tumor tissues helps to establish the immunosuppressive tumor microenvironment and to promote tumor development. Regulation of Ado metabolism is particularly pivotal for blocking Ado-mediated immunosuppression. The activity of adenosine kinase (ADK) for catalyzing the phosphorylation of Ado plays an essential role in regulating Ado metabolism. Specifically, accumulated Ado in the tumor microenvironment occupies the active site of ADK, inhibiting the phosphorylation of Ado. Phosphate can protect ADK from inactivation and restore the activity of ADK. Herein, calcium phosphate-reinforced iron-based metal-organic frameworks (CaP@Fe-MOFs) are designed to reduce Ado accumulation and to inhibit Ado-mediated immunosuppressive response in the tumor microenvironment. CaP@Fe-MOFs are found to regulate the Ado metabolism by promoting ADK-mediated phosphorylation and relieving the hypoxic tumor microenvironment. Moreover, CaP@Fe-MOFs can enhance the antitumor immune response via Ado regulation, including the increase of T lymphocytes and dendritic cells and the decrease of regulatory T lymphocytes. Finally, CaP@Fe-MOFs are used for cancer treatment in mice, alleviating the Ado-mediated immunosuppressive response and achieving tumor suppression. This study may offer a general strategy for blocking the Ado-mediated immunosuppression in the tumor microenvironment and further for enhancing the immunotherapy efficacy in vivo.

Postoperative Natural Killer Cell Dysfunction: The Prime Suspect in the Case of Metastasis Following Curative Cancer Surgery

Surgical resection is the foundation for the curative treatment of solid tumors. However, metastatic recurrence due to the difficulty in eradicating micrometastases remain a feared outcome. Paradoxically, despite the beneficial effects of surgical removal of the primary tumor, the physiological stress resulting from surgical trauma serves to promote cancer recurrence and metastasis. The postoperative environment suppresses critical anti-tumor immune effector cells, including Natural Killer (NK) cells. The literature suggests that NK cells are critical mediators in the formation of metastases immediately following surgery. The following review will highlight the mechanisms that promote the formation of micrometastases by directly or indirectly inducing NK cell suppression following surgery. These include tissue hypoxia, neuroendocrine activation, hypercoagulation, the pro-inflammatory phase, and the anti-inflammatory phase. Perioperative therapeutic strategies designed to prevent or reverse NK cell dysfunction will also be examined for their potential to improve cancer outcomes by preventing surgery-induced metastases.

Blocking HIF to Enhance NK Cells: Hints for New Anti-Tumor Therapeutic Strategies?

Natural Killer (NK) cells are becoming an ever more promising tool to design new anti-tumor strategies. However, two major issues are still a challenge to obtain versatile and effective NK-based therapies: the way to maximize the persistency of powerful NK effectors in the patient, and the way to overcome the multiple escape mechanisms that keep away or suppress NK cells at the tumor site. In this regard, targeting the hypoxia-inducible factors (HIFs), which is important for both tumor progression and immune suppression, may be an opportunity. Especially, in the context of the ongoing studies focused on more effective NK-based therapeutic products.

The Impact of Hypoxia in Early Pregnancy on Placental Cells

Oxygen levels in the placental microenvironment throughout gestation are not constant, with severe hypoxic conditions present during the first trimester. This hypoxic phase overlaps with the most critical stages of placental development, i.e., blastocyst implantation, cytotrophoblast invasion, and spiral artery remodeling initiation. Dysregulation of any of these steps in early gestation can result in pregnancy loss and/or adverse pregnancy outcomes. Hypoxia has been shown to regulate not only the self-renewal, proliferation, and differentiation of trophoblast stem cells and progenitor cells, but also the recruitment, phenotype, and function of maternal immune cells. In this review, we will summarize how oxygen levels in early placental development determine the survival, fate, and function of several important cell types, e.g., trophoblast stem cells, extravillous trophoblasts, syncytiotrophoblasts, uterine natural killer cells, Hofbauer cells, and decidual macrophages. We will also discuss the cellular mechanisms used to cope with low oxygen tensions, such as the induction of hypoxia-inducible factor (HIF) or mammalian target of rapamycin (mTOR) signals, regulation of the metabolic pathway, and adaptation to autophagy. Understanding the beneficial roles of hypoxia in early placental development will provide insights into the root cause(s) of some pregnancy disorders, such as spontaneous abortion, preeclampsia, and intrauterine growth restriction.

HIF1α is required for NK cell metabolic adaptation during virus infection

Natural killer (NK) cells are essential for early protection against virus infection and must metabolically adapt to the energy demands of activation. Here, we found upregulation of the metabolic adaptor hypoxia-inducible factor-1α (HIF1α) is a feature of mouse NK cells during murine cytomegalovirus (MCMV) infection in vivo. HIF1α-deficient NK cells failed to control viral load, causing increased morbidity. No defects were found in effector functions of HIF1αKO NK cells; however, their numbers were significantly reduced. Loss of HIF1α did not affect NK cell proliferation during in vivo infection and in vitro cytokine stimulation. Instead, we found that HIF1α-deficient NK cells showed increased expression of the pro-apoptotic protein Bim and glucose metabolism was impaired during cytokine stimulation in vitro. Similarly, during MCMV infection HIF1α-deficient NK cells upregulated Bim and had increased caspase activity. Thus, NK cells require HIF1α-dependent metabolic functions to repress Bim expression and sustain cell numbers for an optimal virus response.

A hypoxia risk signature for the tumor immune microenvironment evaluation and prognosis prediction in acute myeloid leukemia

Acute myeloid leukemia (AML) is the most prevalent form of acute leukemia. Patients with AML often have poor clinical prognoses. Hypoxia can activate a series of immunosuppressive processes in tumors, resulting in diseases and poor clinical prognoses. However, how to evaluate the severity of hypoxia in tumor immune microenvironment remains unknown. In this study, we downloaded the profiles of RNA sequence and clinicopathological data of pediatric AML patients from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database, as well as those of AML patients from Gene Expression Omnibus (GEO). In order to explore the immune microenvironment in AML, we established a risk signature to predict clinical prognosis. Our data showed that patients with high hypoxia risk score had shorter overall survival, indicating that higher hypoxia risk scores was significantly linked to immunosuppressive microenvironment in AML. Further analysis showed that the hypoxia could be used to serve as an independent prognostic indicator for AML patients. Moreover, we found gene sets enriched in high-risk AML group participated in the carcinogenesis. In summary, the established hypoxia-related risk model could act as an independent predictor for the clinical prognosis of AML, and also reflect the response intensity of the immune microenvironment in AML.

Hypoxia and its impact on the tumour microenvironment of gastroesophageal cancers

The malfeasant role of the hypoxic tumour microenvironment (TME) in cancer progression was recognized decades ago but the exact mechanisms that augment the hallmarks of cancer and promote treatment resistance continue to be elucidated. Gastroesophageal cancers (GOCs) represent a major burden of worldwide disease, responsible for the deaths of over 1 million people annually. Disentangling the impact of hypoxia in GOCs enables a better overall understanding of the disease pathogenesis while shining a light on novel therapeutic strategies and facilitating precision treatment approaches with the ultimate goal of improving outcomes for patients with these diseases. This review discusses the underlying principles and processes of the hypoxic response and the effect of hypoxia in promoting the hallmarks of cancer in the context of GOCs. We focus on its bidirectional influence on inflammation and how it drives angiogenesis, innate and adaptive immune evasion, metastasis, and the reprogramming of cellular bioenergetics. The contribution of the hypoxic GOC TME to treatment resistance is examined and a brief overview of the pharmacodynamics of hypoxia-targeted therapeutics is given. The principal methods that are used in measuring hypoxia and how they may enhance prognostication or provide rationale for individually tailored management in the case of tumours with significant hypoxic regions are also discussed.

The regulation of immune checkpoints by the hypoxic tumor microenvironment

The tumor microenvironment (TME) influences the occurrence and progression of tumors, and hypoxia is an important characteristic of the TME. The expression of programmed death 1 (PD1)/programmed death-ligand 1 (PDL1), cytotoxic T-lymphocyte-associated antigen 4 (CTLA4), and other immune checkpoints in hypoxic malignant tumors is often significantly increased, and is associated with poor prognosis. The application of immune checkpoint inhibitors (ICIs) for treating lung cancer, urothelial carcinoma, and gynecological tumors has achieved encouraging efficacy; however, the rate of efficacy of ICI single-drug treatment is only about 20%. In the present review, we discuss the possible mechanisms by which the hypoxic TME regulates immune checkpoints. By activating hypoxia-inducible factor-1α (HIF-1α), regulating the adenosine (Ado)-A2aR pathway, regulating the glycolytic pathway, and driving epithelial-mesenchymal transition (EMT) and other biological pathways, hypoxia regulates the expression levels of CTLA4, PD1, PDL1, CD47, lymphocyte activation gene 3 (LAG3), T-cell immunoglobulin and mucin domain 3 (TIM3), and other immune checkpoints, which interfere with the immune effector cell anti-tumor response and provide convenient conditions for tumors to escape immune surveillance. The combination of HIF-1α inhibitors, Ado-inhibiting tumor immune microenvironment regulatory drugs, and other drugs with ICIs has good efficacy in both preclinical studies and phase I-II clinical studies. Exploring the effects of TME hypoxia on the expression of immune checkpoints and the function of infiltrating immune cells has greatly clarified the relationship between the hypoxic TME and immune escape, which is of great significance for the development of new drugs and the search for predictive markers of the efficacy of immunotherapy for treating malignant tumors. In the future, combination therapy with hypoxia pathway inhibitors and ICIs may be an effective anti-tumor treatment strategy.

Investigating genetic drivers of juvenile dermatomyositis pathogenesis using bioinformatics methods

Juvenile dermatomyositis (JDM) is a chronic autoimmune disease. The pathogenic mechanisms remain ill-defined. The purpose of this study was to identify key genes related to JDM. Microarray datasets were downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEG) were identified. Then, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, and protein-protein interaction (PPI) network were carried out. In addition, the hub genes were selected by cytoHubba. The expression profile and diagnostic capacity (receiver-operator curve [ROC]) of interested hub genes were verified. Gene set enrichment analysis (GSEA) was also carried out. Moreover, the signature of hub genes was then used as a search query to explore the Connectivity Map (CMAP). A total of 128 DEG were identified. The enriched functions and pathways of the DEG include response to virus, negative regulation of cell migration, cadmium ion transmembrane transport, defense response to Gram-negative bacterium, positive regulation of megakaryocyte differentiation, and negative regulation of angiogenesis. Twenty-one hub genes were identified. The expression levels of the interested genes were also confirmed. ROC analysis confirmed that the expression of these genes can distinguish JDM from controls. GSEA showed that these genes are mainly related to "inflammatory response", "complement", "interferon-α response", "IL6/JAK/STAT3 signaling", "TGF-β signaling", "IL2/STAT5 signaling" and "TNF-α signaling via NF-κB". The CMAP research found some compounds with the potential to counteract the effects of the dysregulated molecular signature in JDM. In this study, bioinformatics methods were used to identify DEG, which helps us understand the molecular mechanisms of JDM and provide candidate targets for diagnosis and treatment of JDM.

STAT3 governs the HIF-1α response in IL-15 primed human NK cells

Natural killer (NK) cells mediate innate host defense against microbial infection and cancer. Hypoxia and low glucose are characteristic for these tissue lesions but do not affect early interferon (IFN) γ and CC chemokine release by interleukin 15 (IL-15) primed human NK cells in vitro. Hypoxia inducible factor 1α (HIF-1α) mediates cellular adaption to hypoxia. Its production is supported by mechanistic target of rapamycin complex 1 (mTORC1) and signal transducer and activator of transcription 3 (STAT3). We used chemical inhibition to probe the importance of mTORC1 and STAT3 for the hypoxia response and of STAT3 for the cytokine response in isolated and IL-15 primed human NK cells. Cellular responses were assayed by magnetic bead array, RT-PCR, western blotting, flow cytometry, and metabolic flux analysis. STAT3 but not mTORC1 activation was essential for HIF-1α accumulation, glycolysis, and oxygen consumption. In both primed normoxic and hypoxic NK cells, STAT3 inhibition reduced the secretion of CCL3, CCL4 and CCL5, and it interfered with IL-12/IL-18 stimulated IFNγ production, but it did not affect cytotoxic granule degranulation up on target cell contact. We conclude that IL-15 priming promotes the HIF-1α dependent hypoxia response and the early cytokine response in NK cells predominantly through STAT3 signaling.

Natural killer cell therapy for hematologic malignancies: successes, challenges, and the future

The adoptive transfer of natural killer (NK) cells is an emerging therapy in the field of immuno-oncology. In the last 3 decades, NK cells have been utilized to harness the anti-tumor immune response in a wide range of malignancies, most notably with early evidence of efficacy in hematologic malignancies. NK cells are dysfunctional in patients with hematologic malignancies, and their number and function are further impaired by chemotherapy, radiation, and immunosuppressants used in initial therapy and hematopoietic stem cell transplantation. Restoring this innate immune deficit may lead to improved therapeutic outcomes. NK cell adoptive transfer has proven to be a safe in these settings, even in the setting of HLA mismatch, and a deeper understanding of NK cell biology and optimized expansion techniques have improved scalability and therapeutic efficacy. Here, we review the use of NK cell therapy in hematologic malignancies and discuss strategies to further improve the efficacy of NK cells against these diseases.

Harnessing NK cells for cancer immunotherapy: immune checkpoint receptors and chimeric antigen receptors

Natural killer (NK) cells, key antitumor effectors of the innate immune system, are endowed with the unique ability to spontaneously eliminate cells undergoing a neoplastic transformation. Given their broad reactivity against diverse types of cancer and close association with cancer prognosis, NK cells have gained considerable attention as a promising therapeutic target for cancer immunotherapy. NK cell-based therapies have demonstrated favorable clinical efficacies in several hematological malignancies but limited success in solid tumors, thus highlighting the need to develop new therapeutic strategies to restore and optimize antitumor activity while preventing tumor immune escape. The current therapeutic modalities yielding encouraging results in clinical trials include the blockade of immune checkpoint receptors to overcome the immune-evasion mechanism used by tumors and the incorporation of tumor-directed chimeric antigen receptors to enhance NK cell antitumor specificity and activity. These observations, together with recent advances in the understanding of NK cell activation within the tumor microenvironment, will facilitate the optimal design of NK cell-based therapy against a broad range of cancers and, more desirably, refractory cancers.

Arrested development: suppression of NK cell function in the tumor microenvironment

Natural killer (NK) cells are cytotoxic innate lymphocytes that protect against viral infection and tumor metastasis. Despite their inherent ability to kill a broad range of virally infected, stressed and transformed cells, low numbers of dysfunctional NK cells are often observed in many advanced solid human cancers. Here, we review the potential mechanisms that influence suboptimal mature NK cell recruitment and function in the tumor microenvironment (TME) of solid tumors. We further highlight current immunotherapy approaches aimed to circumvent NK cell dysfunction and discuss next-generation strategies to enhance adoptive NK cell therapy through targeting intrinsic and extrinsic checkpoints the regulate NK cell functionality in the TME. Understanding the mechanisms that drive NK cell dysfunction in the TME will lead to novel immunotherapeutic approaches in the fight against cancer.

Hypoxia and the phenomenon of immune exclusion

Over the last few years, cancer immunotherapy experienced tremendous developments and it is nowadays considered a promising strategy against many types of cancer. However, the exclusion of lymphocytes from the tumor nest is a common phenomenon that limits the efficiency of immunotherapy in solid tumors. Despite several mechanisms proposed during the years to explain the immune excluded phenotype, at present, there is no integrated understanding about the role played by different models of immune exclusion in human cancers. Hypoxia is a hallmark of most solid tumors and, being a multifaceted and complex condition, shapes in a unique way the tumor microenvironment, affecting gene transcription and chromatin remodeling. In this review, we speculate about an upstream role for hypoxia as a common biological determinant of immune exclusion in solid tumors. We also discuss the current state of ex vivo and in vivo imaging of hypoxic determinants in relation to T cell distribution that could mechanisms of immune exclusion and discover functional-morphological tumor features that could support clinical monitoring.

Genetic Engineering of Natural Killer Cells for Enhanced Antitumor Function

Natural Killer (NK) cells are unique immune cells capable of efficient killing of infected and transformed cells. Indeed, NK cell-based therapies induced response against hematological malignancies in the absence of adverse toxicity in clinical trials. Nevertheless, adoptive NK cell therapies are reported to have exhibited poor outcome against many solid tumors. This can be mainly attributed to limited infiltration of NK cells into solid tumors, downregulation of target antigens on the tumor cells, or suppression by the chemokines and secreted factors present within the tumor microenvironment. Several methods for genetic engineering of NK cells were established and consistently improved over the last decade, leading to the generation of novel NK cell products with enhanced anti-tumor activity and improved tumor homing. New generations of engineered NK cells are developed to better target refractory tumors and/or to overcome inhibitory tumor microenvironment. This review summarizes recent improvements in approaches to NK cell genetic engineering and strategies implemented to enhance NK cell effector functions.

Immune checkpoint molecules in natural killer cells as potential targets for cancer immunotherapy

Recent studies have demonstrated the potential of natural killer (NK) cells in immunotherapy to treat multiple types of cancer. NK cells are innate lymphoid cells that play essential roles in tumor surveillance and control that efficiently kill the tumor and do not require the major histocompatibility complex. The discovery of the NK's potential as a promising therapeutic target for cancer is a relief to oncologists as they face the challenge of increased chemo-resistant cancers. NK cells show great potential against solid and hematologic tumors and have progressively shown promise as a therapeutic target for cancer immunotherapy. The effector role of these cells is reliant on the balance of inhibitory and activating signals. Understanding the role of various immune checkpoint molecules in the exhaustion and impairment of NK cells when their inhibitory receptors are excessively expressed is particularly important in cancer immunotherapy studies and clinical implementation. Emerging immune checkpoint receptors and molecules have been found to mediate NK cell dysfunction in the tumor microenvironment; this has brought up the need to explore further additional NK cell-related immune checkpoints that may be exploited to enhance the immune response to refractory cancers. Accordingly, this review will focus on the recent findings concerning the roles of immune checkpoint molecules and receptors in the regulation of NK cell function, as well as their potential application in tumor immunotherapy.

Injecting Immunosuppressive M2 Macrophages Alleviates the Symptoms of Periodontitis in Mice

Periodontitis is the second most common oral disease affecting tooth-supporting structures. The tissue damage is mainly initiated by the excessive secretion of proinflammatory cytokines by immune cells. Macrophages are a type of antigen-presenting cells that influence the adaptive immunity function. We used a unique set of cytokines, i.e., a combination of IL-4, IL-13, and IL-10, to stimulate macrophages into a subset of M2 polarization cells that express much higher levels of ARG-1, CD206, and PDL-2 genes. The cells’ anti-inflammatory potential was tested with mixed-lymphocyte reaction assay, which showed that this subset of macrophages could increase IL-2 secretion and suppress IL-17, IL-6, and TNF-α secretion by splenocytes. The gram-negative bacterial species Porphyromonas gingivalis was used to initiate an inflammatory process in murine periodontal tissues. In the meantime, cell injection therapy was used to dampen the excessive immune reaction and suppress osteoclast differentiation during periodontitis. Maxilla was collected and analyzed for osteoclast formation. The results indicated that mice in the cell injection group exhibited less osteoclast activity within the periodontal ligament region than in the periodontitis group. Moreover, the injection of M2 macrophages sustained the regulatory population ratio. Therefore, the M2 macrophages induced under the stimulation of IL-4, IL-13, and IL-10 combined had tremendous immune modulation ability. Injecting these cells into local periodontal tissue could effectively alleviate the symptom of periodontitis.