Altered recognition of antigen is a mechanism of CD8+ T cell tolerance in cancer

Amplifying glioblastoma immunotherapy: T cell shielding through Nitric oxide/reactive oxygen species scavenging nanoparticles Potentiates anti-PD-1

Despite the success of immune checkpoint blockade (ICB) therapy in various cancers, its efficacy faces challenges in glioblastoma (GBM) due to the immunosuppressive cold-tumor microenvironment. The scarcity of tumor-infiltrating T cells and the suppression of T cell activity significantly limit therapeutic outcomes in GBM. Nitric oxide (NO) and reactive oxygen species (ROS) from tumor-associated myeloid cells (TAMCs) are key contributors to T cell suppression, reducing ICB therapy effectiveness. In this study, we developed NO-ROS scavenging micelles that effectively scavenge both NO and ROS, protecting T cells from their exhausting effects. This leads to a significant increase in T cell infiltration and activation. Moreover, when combined with αPD-1, the survival rate increases to 40 % up to 120 days, enhancing therapeutic efficacy compared to αPD-1 alone. This approach not only protects T cells from the inhibitory effects of NO and ROS but also has the potential to reshape the tumor microenvironment, overcoming T cell suppression in cold tumors.

SCFA biotherapy delays diabetes in humanized gnotobiotic mice by remodeling mucosal homeostasis and metabolome

Type 1 diabetes (T1D) is linked to an altered gut microbiota characterized by reduced short-chain fatty acid (SCFA) production. Oral delivery of a SCFA-yielding biotherapy in adults with T1D was followed by increased SCFAs, altered gut microbiota and immunoregulation, as well as delaying diabetes in preclinical models. Here, we show that SCFA-biotherapy in humans is accompanied by remodeling of the gut proteome and mucosal immune homeostasis. Metabolomics showed arginine, glutamate, nucleotide and tryptophan metabolism were enriched following the SCFA-biotherapy, and found metabolites that correlated with glycemic control. Fecal microbiota transfer demonstrated that the microbiota of SCFA-responders delayed diabetes progression in humanized gnotobiotic mice. The protected mice increased similar metabolite pathways to the humans including producing aryl-hydrocarbon receptor ligands and reducing inflammatory mucosal immunity and increasing IgA production in the gut. These data demonstrate that a potent SCFA immunomodulator promotes multiple beneficial pathways and supports targeting the microbiota as an approach against T1D. Trial registration: Australia New Zealand Clinical Trials Registry ACTRN12618001391268.

Myeloid-derived suppressor cell inhibits T-cell-based defense against Klebsiella pneumoniae infection via IDO1 production

Klebsiella pneumoniae (Kp) is responsible for a wide range of infections, including pneumonia, sepsis, and urinary tract infections. However, the treatment options are limited due to the continuous evolution of drug-resistant and hypervirulent variants. It is crucial to investigate the mechanisms behind the high mortality rate of hypervirulent Kp (hvKp) strains to develop new strategies for preventing hvKp from evading the host's defenses and improving treatment effectiveness for these fatal infections. In this study, we used a hvKp-induced mouse bacteremia model and performed single-cell RNA sequencing to investigate the effects of hvKp infection. Our findings demonstrated that hvKp infection led to a decrease in lymphocytes (lymphopenia), attributed to impaired proliferation and apoptosis. The infiltration of myeloid-derived suppressor cells (MDSCs) in the infected lungs was confirmed to suppress T cell proliferation, leading to lymphopenia. We further identified that hvKp promotes tryptophan metabolism in infected lungs, enhancing the immunosuppressive activity of MDSCs by inducing the production of the enzyme IDO1. Our ex vivo inhibition experiment revealed that L-kynurenine, a product of tryptophan metabolism, inhibits T-cell proliferation and induces T-cell apoptosis, further suppressing T-cell mediated responses against bacteria. Importantly, when we knocked out the Ido1 gene or inhibited IDO1 expression using a specific inhibitor 1-MT in mice, we observed a significant enhancement in T-cell mediated responses against hvKp. These findings highlight the crucial role of MDSCs in hvKp-induced bacteremia and suggest a promising immunotherapeutic approach by inhibiting IDO1 production to combat infectious diseases.

Tumor-infiltrating myeloid cells; mechanisms, functional significance, and targeting in cancer therapy

Tumor-infiltrating myeloid cells (TIMs), which encompass tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), and tumor-associated dendritic cells (TADCs), are of great importance in tumor microenvironment (TME) and are integral to both pro- and anti-tumor immunity. Nevertheless, the phenotypic heterogeneity and functional plasticity of TIMs have posed challenges in fully understanding their complexity roles within the TME. Emerging evidence suggested that the presence of TIMs is frequently linked to prevention of cancer treatment and improvement of patient outcomes and survival. Given their pivotal function in the TME, TIMs have recently been recognized as critical targets for therapeutic approaches aimed at augmenting immunostimulatory myeloid cell populations while depleting or modifying those that are immunosuppressive. This review will explore the important properties of TIMs related to immunity, angiogenesis, and metastasis. We will also document the latest therapeutic strategies targeting TIMs in preclinical and clinical settings. Our objective is to illustrate the potential of TIMs as immunological targets that may improve the outcomes of existing cancer treatments.

Extracellular Vesicle-Based Strategies for Tumor Immunotherapy

Immunotherapy is one of the most promising approaches for cancer management, as it utilizes the intrinsic immune response to target cancer cells. Normally, the human body uses its immune system as a defense mechanism to detect and eliminate foreign objects, including cancer cells. However, cancers develop a 'switch off' mechanism, known as immune checkpoint proteins, to evade immune surveillance and suppress immune activation. Therefore, significant efforts have been made to develop the strategies for stimulating immune responses against cancers. Among these, the use of extracellular vesicles (EVs) to enhance the anti-tumor immune response has emerged as a particularly promising approach in cancer management. EVs possess several unique properties that elevate the potency in modulating immune responses. This review article provides a comprehensive overview of recent advances in this field, focusing on the strategic usage of EVs to overcome tumor-induced immune tolerance. We discuss the biogenesis and characteristics of EVs, as well as their potential applications in medical contexts. The immune mechanisms within the tumor microenvironment and the strategies employed by cancers to evade immune detection are explored. The roles of EVs in regulating the tumor microenvironment and enhancing immune responses for immunotherapy are also highlighted. Additionally, this article addresses the challenges and future directions for the development of EV-based nanomedicine approaches, aiming to improve cancer immunotherapy outcomes with greater precision and efficacy while minimizing off-target effects.

The Tight Relationship Between the Tumoral Microenvironment and Radium-223

Radium-223 (223Ra) was the first radioactive isotope approved for treating castration-resistant prostate cancer (CRPC) with symptomatic bone metastases without visceral metastatic disease. To better understand the action of 223Ra, its role in the tumor microenvironment represents a crucial aspect. A literature search was conducted using the PubMed/MEDLINE database and studies regarding the relationship between 223Ra and the tumoral microenvironment were considered. The tumoral microenvironment is a complex setting in which complex interactions between cells and molecules occur. Radium-223, as an alpha-emitter, induces double-stranded DNA breaks; to potentiate this effect, it could be used in patients with genetic instability but also in combination with therapies which inhibit DNA repair, modulate the immune response, or control tumor growth. In conclusion, a few studies have taken into consideration the tumoral microenvironment in association with 223Ra. However, its understanding is a priority to better comprehend how to effectively exploit 223Ra and its action mechanism.

Tumor secretome shapes the immune landscape during cancer progression

The focus of cancer immunotherapy has traditionally been on immune cells and tumor cells themselves, often overlooking the tumor secretome. This review provides a comprehensive overview of the intricate relationship between tumor cells and the immune response in cancer progression. It highlights the pivotal role of the tumor secretome - a diverse set of molecules secreted by tumor cells - in significantly influencing immune modulation, promoting immunosuppression, and facilitating tumor survival. In addition to elucidating these complex interactions, this review discusses current clinical trials targeting the tumor secretome and highlights their potential to advance personalized medicine strategies. These trials aim to overcome the challenges of the tumor microenvironment by designing therapies tailored to the secretome profiles of individual cancer patients. In addition, advances in proteomic techniques are highlighted as essential tools for unraveling the complexity of the tumor secretome, paving the way for improved cancer treatment outcomes.

Cancer stem cells and tumor-associated macrophages as mates in tumor progression: mechanisms of crosstalk and advanced bioinformatic tools to dissect their phenotypes and interaction

Cancer stem cells (CSCs) are a small subset within the tumor mass significantly contributing to cancer progression through dysregulation of various oncogenic pathways, driving tumor growth, chemoresistance and metastasis formation. The aggressive behavior of CSCs is guided by several intracellular signaling pathways such as WNT, NF-kappa-B, NOTCH, Hedgehog, JAK-STAT, PI3K/AKT1/MTOR, TGF/SMAD, PPAR and MAPK kinases, as well as extracellular vesicles such as exosomes, and extracellular signaling molecules such as cytokines, chemokines, pro-angiogenetic and growth factors, which finely regulate CSC phenotype. In this scenario, tumor microenvironment (TME) is a key player in the establishment of a permissive tumor niche, where CSCs engage in intricate communications with diverse immune cells. The "oncogenic" immune cells are mainly represented by B and T lymphocytes, NK cells, and dendritic cells. Among immune cells, macrophages exhibit a more plastic and adaptable phenotype due to their different subpopulations, which are characterized by both immunosuppressive and inflammatory phenotypes. Specifically, tumor-associated macrophages (TAMs) create an immunosuppressive milieu through the production of a plethora of paracrine factors (IL-6, IL-12, TNF-alpha, TGF-beta, CCL1, CCL18) promoting the acquisition by CSCs of a stem-like, invasive and metastatic phenotype. TAMs have demonstrated the ability to communicate with CSCs via direct ligand/receptor (such as CD90/CD11b, LSECtin/BTN3A3, EPHA4/Ephrin) interaction. On the other hand, CSCs exhibited their capacity to influence immune cells, creating a favorable microenvironment for cancer progression. Interestingly, the bidirectional influence of CSCs and TME leads to an epigenetic reprogramming which sustains malignant transformation. Nowadays, the integration of biological and computational data obtained by cutting-edge technologies (single-cell RNA sequencing, spatial transcriptomics, trajectory analysis) has significantly improved the comprehension of the biunivocal multicellular dialogue, providing a comprehensive view of the heterogeneity and dynamics of CSCs, and uncovering alternative mechanisms of immune evasion and therapeutic resistance. Moreover, the combination of biology and computational data will lead to the development of innovative target therapies dampening CSC-TME interaction. Here, we aim to elucidate the most recent insights on CSCs biology and their complex interactions with TME immune cells, specifically TAMs, tracing an exhaustive scenario from the primary tumor to metastasis formation.

Harnessing amino acid pathways to influence myeloid cell function in tumor immunity

Amino acids are pivotal regulators of immune cell metabolism, signaling pathways, and gene expression. In myeloid cells, these processes underlie their functional plasticity, enabling shifts between pro-inflammatory, anti-inflammatory, pro-tumor, and anti-tumor activities. Within the tumor microenvironment, amino acid metabolism plays a crucial role in mediating the immunosuppressive functions of myeloid cells, contributing to tumor progression. This review delves into the mechanisms by which specific amino acids-glutamine, serine, arginine, and tryptophan-regulate myeloid cell function and polarization. Furthermore, we explore the therapeutic potential of targeting amino acid metabolism to enhance anti-tumor immunity, offering insights into novel strategies for cancer treatment.

Tumor microenvironment regulation by reactive oxygen species-mediated inflammasome activation

Tumor microenvironment (TME) is composed of diverse cell types whose interactions, both direct and indirect, significantly influence tumorigenesis and therapeutic outcomes. Within TME, reactive oxygen species (ROS) are produced by various cells and exhibit a dual role: moderate ROS levels promote tumor initiation and progression, whereas excessive levels induce cancer cell death, influencing the efficacy of anticancer therapies. Inflammasomes, cytosolic multiprotein complexes, are pivotal in multiple stages of tumorigenesis and play a crucial role in establishing the inflammatory TME. By releasing cytokines such as IL-1β and IL-18, inflammasomes contribute to immune cell recruitment and sustain a chronic inflammatory state that supports tumor growth. ROS are critical regulators of inflammasome activation, with the impact of ROS-mediated activation differing across cell types, leading to distinct influences on tumor progression and therapeutic responses. This review explores how ROS drive inflammasome activation in various TME-associated cells and the reciprocal ROS generation induced by inflammasomes, examining their multifaceted impact on tumorigenesis and therapeutic efficacy. By elucidating the complex interplay between ROS and inflammasomes in TME, we provide insights into potential therapeutic approaches that could modulate cancer progression and enhance treatment outcomes.

Arginine metabolism in myeloid cells in health and disease

Metabolic flexibility is key for the function of myeloid cells. Arginine metabolism is integral to the regulation of myeloid cell responses. Nitric oxide (NO) production from arginine is vital for the antimicrobial and pro-inflammatory responses. Conversely, the arginase 1 (ARG1)-dependent switch between the branch of NO production and polyamine synthesis downregulates inflammation and promotes recovery of tissue homeostasis. Creatine metabolism is key for energy supply and proline metabolism is required for collagen synthesis. Myeloid ARG1 also regulates extracellular arginine availability and T cell responses in parasitic diseases and cancer. Cancer, surgery, sepsis and persistent inflammation in chronic inflammatory diseases, such as neuroinflammatory diseases or arthritis, are associated with dysregulation of arginine metabolism in myeloid cells. Here, we review current knowledge on arginine metabolism in different myeloid cell types, such as macrophages, neutrophils, microglia, osteoclasts, tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs) and myeloid-derived suppressor cells (MDSCs). A deeper understanding of the function of arginine metabolism in myeloid cells will improve our knowledge on the pathology of several diseases and may set the platform for novel therapeutic applications.

PMN-MDSCs are responsible for immune suppression in anti-PD-1 treated TAP1 defective melanoma

INTRODUCTION

The transporter associated with antigen processing (TAP) is a key component of the classical HLA I antigen presentation pathway. Our previous studies have demonstrated that the downregulation of TAP1 contributes to tumor progression and is associated with an increased presence of myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment. However, it remains unclear whether the elevation of MDSCs leads to immune cell exhaustion in tumors lacking TAP1. In this study, we established mouse models of tumors with TAP1 deficiency, and we employed PMN-MDSC depletion to investigate their impact on the immune microenvironment within the tumors. We found that MDSC depletion significantly altered the immune-suppressive effects of TAP1-deficient tumor when anti-PD-1 treatment was administered. Targeting PMN-MDSC may be a promising therapeutic strategy for the treatment of tumors with TAP1 deficiency during ICB treatment.

METHODS

Immunohistochemistry (IHC) was conducted to assess TAP1 expression in mouse melanoma tissues. Ly6G, F4/80, and NKp46 markers were detected in B16 parental and TAP1 knockout tissues, respectively. To enhance anti-tumor immunity, hyperthermia-treated B16F10 WT cell suspension was injected prior to tumor cell introduction. Subsequently, we established B16F10 TAP1 knockout and WT melanoma mouse models. Tumors were collected, and the immune microenvironment was monitored accordingly. Anti-Ly6G antibody was administered to deplete polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Finally, flow cytometry analysis for immune infiltration, quantitative PCR for cytokine levels, and immunofluorescence assays were performed to analyze the immune response.

RESULTS

The level of Ly6G+ cell infiltration was significantly higher in samples exhibiting low TAP1 expression, while no differences were observed in the infiltration of F4/80+ cells or NKp46+ cells. Furthermore, the immune-suppressive effects associated with PMN-MDSCs were reversed following their elimination; this resulted in an increase in CD8+ T cells and a higher ratio of CD8+ T cells to Tregs, while the infiltration of innate immune cells remained unaffected. Functional markers of these immune cells indicated an active anti-tumoral immune response following the removal of PMN-MDSCs. Quantitative PCR analysis indicated elevated levels of TNF-α and IL-6, accompanied by decreased levels of TGF-β in the tumor microenvironment of TAP1.

CONCLUSIONS

Our data indicate that myeloid-derived suppressor cells (PMN-MDSCs) play an essential role in creating a tumorigenic immune microenvironment in TAP1 knockout tumors. Therefore, targeting PMN-MDSCs may become a promising therapeutic strategy for the treatment of tumors with TAP1 deficiency during ICB treatment.

Metabolic regulation of myeloid-derived suppressor cells in tumor immune microenvironment: targets and therapeutic strategies

Cancer remains a major challenge to global public health, with rising incidence and high mortality rates. The tumor microenvironment (TME) is a complex system of immune cells, fibroblasts, extracellular matrix (ECM), and blood vessels that form a space conducive to cancer cell proliferation. Myeloid-derived suppressor cells (MDSCs) are abundant in tumors, and they drive immunosuppression through metabolic reprogramming in the TME. This review describes how metabolic pathways such as glucose metabolism, lipid metabolism, amino acid metabolism, and adenosine metabolism have a significant impact on the function of MDSCs by regulating their immunosuppressive activity and promoting their survival and expansion in tumors. The review also explores key metabolic targets in MDSCs and strategies to modulate MDSC metabolism to improve the tumor immune microenvironment and enhance anti-tumor immune responses. Understanding these pathways can provide insight into potential therapeutic targets for modulating MDSC activity and improving outcomes of cancer immunotherapies.

The heterogeneity of neutrophils in cancer and its implication for therapeutic targeting

Neutrophils have a pivotal role in safeguarding the host against pathogens and facilitating tissue remodeling. They possess a large array of tools essential for executing these functions. Neutrophils have a critical role in cancer, where they are largely associated with negative clinical outcome and resistance to therapy. However, the specific role of neutrophils in cancer is complex and controversial, owing to their high functional diversity and acute sensitivity to the microenvironment. In this Perspective, we discuss the accumulated evidence that suggests that the functional diversity of neutrophils can be ascribed to two principal functional states, each with distinct characteristics: classically activated neutrophils and pathologically activated immunosuppressive myeloid-derived suppressor cells. We discuss how the antimicrobial factors in neutrophils can contribute to tumor progression and the fundamental mechanisms that govern the pathologically activated myeloid-derived suppressor cells. These functional states play divergent roles in cancer and thus require separate consideration in therapeutic targeting.

Neutrophil and Colorectal Cancer

Colorectal cancer (CRC) is often associated with metastasis and recurrence and is the leading cause of cancer-related mortality. In the progression of CRC, recent studies have highlighted the critical role of neutrophils, particularly tumor-associated neutrophils (TANs). TANs have both tumor-promoting and tumor-suppressing activities, contributing to metastasis, immunosuppression, angiogenesis, and epithelial-to-mesenchymal transition. Tumor-promoting TANs promote tumor growth by releasing proteases, reactive oxygen species, and cytokines, whereas tumor-suppressing TANs enhance immune responses by activating T cells and natural killer cells. Understanding the mechanisms underlying TAN mobilization, plasticity, and their role in the tumor microenvironment has revealed potential therapeutic targets. This review provides a comprehensive overview of TAN biology in CRC and discusses both the tumor-promoting and tumor-suppressing functions of neutrophils. Novel therapeutic approaches targeting TANs, such as chemokine receptor antagonists, aim to modulate neutrophil reprogramming and offer promising avenues for improving treatment outcomes of CRC.

MDSC: a new potential breakthrough in CAR-T therapy for solid tumors

Chimeric antigen receptor T (CAR-T) cell therapy has shown remarkable success in hematologic malignancies but has encountered challenges in effectively treating solid tumors. One major obstacle is the presence of the immunosuppressive tumor microenvironment (TME), which is mainly built by myeloid-derived suppressor cells (MDSCs). Recent studies have shown that MDSCs have a detrimental effect on CAR-T cells due to their potent immunosuppressive capabilities. Targeting MDSCs has shown promising results to enhance CAR-T immunotherapy in preclinical solid tumor models. In this review, we first highlight that MDSCs increase tumor proliferation, transition, angiogenesis and encourage circulating tumor cells (CTCs) extravasation leading to tumor progression and metastasis. Moreover, we describe the main characteristics of the immunosuppressive activities of MDSCs on T cells in TME. Most importantly, we summarize targeting therapeutic strategies of MDSCs in CAR-T therapies against solid tumors. These strategies include (1) therapeutic targeting of MDSCs through small molecule inhibitors and large molecule antibodies; (2) CAR-T targeting cancer cell antigen combination with MDSC modulatory agents; (3) cytokine receptor antigen-targeted CAR-T indirectly or directly targeting MDSCs reshapes TME; (4) modified natural killer (NK) cells expressing activating receptor directly targeting MDSCs; and (5) CAR-T directly targeting MDSC selective antigens. In the near future, we are expected to witness the improvement of CAR-T cell therapies for solid tumors by targeting MDSCs in clinical practice.

Exosomal integrins in tumor progression, treatment and clinical prediction (Review)

Integrins are a large family of cell adhesion molecules involved in tumor cell differentiation, migration, proliferation and neovascularization. Tumor cell‑derived exosomes carry a large number of integrins, which are closely associated with tumor progression. As crucial mediators of intercellular communication, exosomal integrins have gained attention in the field of cancer biology. The present review examined the regulatory mechanisms of exosomal integrins in tumor cell proliferation, migration and invasion, and emphasized their notable roles in tumor initiation and progression. The potential of exosomal integrins as drug delivery systems in cancer treatment was explored. Additionally, the potential of exosomal integrins in clinical tumor prediction was considered, while summarizing their applications in diagnosis, prognosis assessment and treatment response prediction. Thus, the present review aimed to provide guidance and insights for future basic research and the clinical translation of exosomal integrins. The study of exosomal integrins is poised to offer new perspectives and methods for precise cancer treatment and clinical prediction.

Identification and validation of ion channels-related mRNA prognostic signature for glioblastomas

Glioblastomas (GBM) is a kind of malignant brain tumor with poor prognosis. Identifying new biomarkers is promising for the treatment of GBM. The mRNA-seq and clinical data were obtained from The Cancer Genome Atlas and the Chinese Glioma Genome Atlas databases. The differentially expressed genes were identified using limma R package. The prognosis-related genes were screened out and a risk model was constructed using univariate, least absolute shrinkage and selection operator, and multivariate Cox analysis. Receiver operating characteristic curve was used to assess the efficiency of model. Kaplan-Meier survival curve was applied for the survival analysis. Mutation analysis was conducted using maftools package. The effect of immunotherapy was analyzed according to TIDE score, and the drug sensitivity analysis was performed. The Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Gene Set Enrichment Analysis enrichment analyses were performed for the functional analysis. The regulatory network was constructed by STRING and Cytoscape software. RT-qPCR was performed to validate the expression of 3 hub genes in vitro. A risk model was constructed based on 3 ion channels related genes (gap junction protein beta 2 [GJB2], potassium voltage-gated channel subfamily h member 6 [KCNH6], and potassium calcium-activated channel subfamily n member 4 [KCNN4]). The risk score and hub genes were positively correlated with the calcium signaling pathway. Patients were divided into 2 groups based on the risk score calculated by 3 signatures. The infiltration levels of T cell, B lineage, monocytic lineage, and neutrophils were increased in high risk group, while TIDE score was decreased. IC50 of potential drugs for GBM treatment was elevated in the high risk group. Furthermore, GJB2, KCNH6, and KCNN4 were oncogenic, and GJB2 and KCNN4 were upregulated, while KCNH6 was downregulated in high risk group and GBM cells. The regulatory network showed that KCNH6 was targeted by more miRNA and transcription factors and KCNN4 interacted with more drugs. We constructed a three-signature risk model, which could effectively predict the prognosis of GBM development. Besides, KCNH6 and KCNN4 were respectively considered as the targets of molecular targeted treatment and chemotherapy.

Application of nanotechnology in the treatment of hepatocellular carcinoma

Hepatocellular carcinoma is the predominant histologic variant of hepatic malignancy and has become a major challenge to global health. The increasing incidence and mortality of hepatocellular carcinoma has created an urgent need for effective prevention, diagnosis, and treatment strategies. This is despite the impressive results of multiple treatments in the clinic. However, the unique tumor immunosuppressive microenvironment of hepatocellular carcinoma increases the difficulty of treatment and immune tolerance. In recent years, the application of nanoparticles in the treatment of hepatocellular carcinoma has brought new hope for tumor patients. Nano agents target tumor-associated fibroblasts, regulatory T cells, myeloid suppressor cells, tumor-associated macrophages, tumor-associated neutrophils, and immature dendritic cells, reversed the immunosuppressive microenvironment of hepatocellular carcinoma. In addition, he purpose of this review is to summarize the advantages of nanotechnology in guiding surgical excision, local ablation, TACE, standard chemotherapy, and immunotherapy, application of nano-vaccines has also continuously enriched the treatment of liver cancer. This study aims to investigate the potential applications of nanotechnology in the management of hepatocellular carcinoma, with the ultimate goal of enhancing therapeutic outcomes and improving the prognosis for patients affected by this malignancy.

Targeting ROS-sensing Nrf2 potentiates anti-tumor immunity of intratumoral CD8+ T and CAR-T cells

Cytotoxic T lymphocytes (CTLs) play a crucial role in cancer rejection. However, CTLs encounter dysfunction and exhaustion in the immunosuppressive tumor microenvironment (TME). Although the reactive oxygen species (ROS)-rich TME attenuates CTL function, the underlying molecular mechanism remains poorly understood. The nuclear factor erythroid 2-related 2 (Nrf2) is the ROS-responsible factor implicated in increasing susceptibility to cancer progression. Therefore, we examined how Nrf2 is involved in anti-tumor responses of CD8+ T and chimeric antigen receptor (CAR) T cells in the ROS-rich TME. Here, we demonstrated that tumor growth in Nrf2-/- mice was significantly controlled and was reversed by T cell depletion and further confirmed that Nrf2 deficiency in T cells promotes anti-tumor responses using an adoptive transfer model of antigen-specific CD8+ T cells. Nrf2-deficient CTLs are resistant to ROS, and their effector functions are sustained in the TME. Furthermore, Nrf2 knockdown in human CAR-T cells enhanced the survival and function of intratumoral CAR-T cells in a solid tumor xenograft model and effectively controlled tumor growth. ROS-sensing Nrf2 inhibits the anti-tumor T cell responses, indicating that Nrf2 may be a potential target for T cell immunotherapy strategies against solid tumors.

ROS: A "booster" for chronic inflammation and tumor metastasis

Reactive oxygen species (ROS) are a group of highly active molecules produced by normal cellular metabolism and play a crucial role in the human body. In recent years, researchers have increasingly discovered that ROS plays a vital role in the progression of chronic inflammation and tumor metastasis. The inflammatory tumor microenvironment established by chronic inflammation can induce ROS production through inflammatory cells. ROS can then directly damage DNA or indirectly activate cellular signaling pathways to promote tumor metastasis and development, including breast cancer, lung cancer, liver cancer, colorectal cancer, and so on. This review aims to elucidate the relationship between ROS, chronic inflammation, and tumor metastasis, explaining how chronic inflammation can induce tumor metastasis and how ROS can contribute to the evolution of chronic inflammation toward tumor metastasis. Interestingly, ROS can have a "double-edged sword" effect, promoting tumor metastasis in some cases and inhibiting it in others. This article also highlights the potential applications of ROS in inhibiting tumor metastasis and enhancing the precision of tumor-targeted therapy. Combining ROS with nanomaterials strategies may be a promising approach to enhance the efficacy of tumor treatment.

Targeting catalase in cancer

Healthy cells have developed a sophisticated network of antioxidant molecules to prevent the toxic accumulation of reactive oxygen species (ROS) generated by diverse environmental stresses. On the opposite, cancer cells often exhibit high levels of ROS and an altered levels of antioxidant molecules compared to normal cells. Among them, the antioxidant enzyme catalase plays an essential role in cell defense against oxidative stress through the dismutation of hydrogen peroxide into water and molecular oxygen, and its expression is often decreased in cancer cells. The elevation of ROS in cancer cells provides them proliferative advantages, and leads to metabolic reprogramming, immune escape and metastasis. In this context, catalase is of critical importance to control these cellular processes in cancer through various mechanisms. In this review, we will discuss the major progresses and challenges in understanding the role of catalase in cancer for this last decade. This review also aims to provide important updates regarding the regulation of catalase expression, subcellular localization and discuss about the potential role of microbial catalases in tumor environment. Finally, we will describe the different catalase-based therapies and address the advantages, disadvantages, and limitations associated with modulating catalase therapeutically in cancer treatment.

Targeted modulation of myeloid-derived suppressor cells in the tumor microenvironment: Implications for cancer therapy

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature myeloid cells originating from the bone marrow, known for their potent immunosuppressive functions that contribute to tumor immune evasion and progression. This paper provides a comprehensive analysis of the multifaceted interactions between MDSCs and tumors, exploring their distinct phenotypes and immunosuppressive mechanisms. Key roles of MDSCs in tumor biology are discussed, including their involvement in the formation of the pre-metastatic niche, facilitation of angiogenesis, enhancement of vascular permeability, suppression of tumor cell apoptosis, and promotion of resistance to cancer therapies. Additionally, the review highlights recent advances in the development of MDSC-targeting therapies, with a focus on their potential to enhance anti-tumor immunity. The therapeutic potential of Traditional Chinese Medicine (TCM) in modulating MDSC quantity and function is also explored, suggesting a novel approach to cancer treatment by integrating traditional and modern therapeutic strategies.

Nanotechnology Applications in Breast Cancer Immunotherapy

Next-generation cancer treatments are expected not only to target cancer cells but also to simultaneously train immune cells to combat cancer while modulating the immune-suppressive environment of tumors and hosts to ensure a robust and lasting response. Achieving this requires carriers that can codeliver multiple therapeutics to the right cancer and/or immune cells while ensuring patient safety. Nanotechnology holds great potential for addressing these challenges. This article highlights the recent advances in nanoimmunotherapeutic development, with a focus on breast cancer. While immune checkpoint inhibitors (ICIs) have achieved remarkable success and lead to cures in some cancers, their response rate in breast cancer is low. The poor response rate in solid tumors is often associated with the low infiltration of anti-cancer T cells and an immunosuppressive tumor microenvironment (TME). To enhance anti-cancer T-cell responses, nanoparticles are employed to deliver ICIs, bispecific antibodies, cytokines, and agents that induce immunogenic cancer cell death (ICD). Additionally, nanoparticles are used to manipulate various components of the TME, such as immunosuppressive myeloid cells, macrophages, dendritic cells, and fibroblasts to improve T-cell activities. Finally, this article discusses the outlook, challenges, and future directions of nanoimmunotherapeutics.

Interactions between fibroblasts and monocyte-derived cells in chronic lung injuries induced by real-ambient particulate matter exposure

Long-term exposure to fine particulate matter (PM2.5) can lead to chronic lung injury, including inflammation, idiopathic pulmonary fibrosis, and cancer. Mesenchymal cells, such as fibroblasts, myeloid-derived suppressor cells (MDSCs), and interstitial macrophages (IMs), contribute to immune regulation in lung, yet their diversity and functions upon long-term exposure to particulate matter (PM) remain inadequately characterized. In this study, we conducted a 16-week real-ambient PM exposure experiment on C57BL/6 J male mice in Shijiazhuang, China. We used single-cell RNA sequencing to analyze the cellular and molecular changes in lung tissues. Notably, we revealed a significant increase in specific fibroblast (ATX+, Col5a1+Meg3+, universal fibroblasts) and monocyte-derived cell subpopulations (monocytic-MDSCs (M-MDSCs), Lyve1loMHC-Ⅱhi IMs, Lyve1hiMHC-Ⅱlo IMs) that exhibited pro-inflammatory and pro-fibrotic functions. These cell subpopulations engaged in immunosuppressive signaling pathways and interactions with various cytokines, shaping a pulmonary microenvironment similar to those associated with cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs). This altered immune environment may promote the development of pulmonary fibrosis caused by PM exposure, underscoring the intricate roles of mesenchymal cells in chronic lung injury and highlighting the cancer-causing potential of PM2.5 exposure.

Developing an erythrocyte‒MHC-I conjugate for cancer treatment

Mature erythrocytes are known to lack major histocompatibility complex (MHC) proteins. However, the presence of MHC molecules on erythrocytes has been occasionally reported, though without a defined function. In this study, we designed erythrocyte conjugated solely with a fusion protein consisting of an antigenic peptide linked to MHC class I (MHC-I) protein, termed MHC-I‒Ery. The modified erythrocyte, decorated with the peptide derived from human papillomavirus (HPV) 16 oncoprotein E6/E7, effectively activated antigen-specific CD8+ T cells in peripheral blood mononuclear cells (PBMCs) from HPV16+ cervical cancer patients. Additionally, MHC-I‒Ery monotherapy was shown to inhibit antigen-positive tumor growth in mice. This treatment immediately activated CD8+ T cells and reduced suppressive myeloid cells in the spleen, leading to systemic anti-tumor activity. Safety and tolerability evaluations of MHC-I‒Ery in non-human primates further supported its clinical potential. Our results first demonstrated that erythrocytes equipped solely with antigen peptide‒MHC-I complexes can robustly stimulate the immune system, suggesting a novel and promising approach for advancing cancer immunotherapy.

Pre-metastatic niche: formation, characteristics and therapeutic implication

Distant metastasis is a primary cause of mortality and contributes to poor surgical outcomes in cancer patients. Before the development of organ-specific metastasis, the formation of a pre-metastatic niche is pivotal in promoting the spread of cancer cells. This review delves into the intricate landscape of the pre-metastatic niche, focusing on the roles of tumor-derived secreted factors, extracellular vesicles, and circulating tumor cells in shaping the metastatic niche. The discussion encompasses cellular elements such as macrophages, neutrophils, bone marrow-derived suppressive cells, and T/B cells, in addition to molecular factors like secreted substances from tumors and extracellular vesicles, within the framework of pre-metastatic niche formation. Insights into the temporal mechanisms of pre-metastatic niche formation such as epithelial-mesenchymal transition, immunosuppression, extracellular matrix remodeling, metabolic reprogramming, vascular permeability and angiogenesis are provided. Furthermore, the landscape of pre-metastatic niche in different metastatic organs like lymph nodes, lungs, liver, brain, and bones is elucidated. Therapeutic approaches targeting the cellular and molecular components of pre-metastatic niche, as well as interventions targeting signaling pathways such as the TGF-β, VEGF, and MET pathways, are highlighted. This review aims to enhance our understanding of pre-metastatic niche dynamics and provide insights for developing effective therapeutic strategies to combat tumor metastasis.

Uncovering therapeutic targets for macrophage-mediated T cell suppression and PD-L1 therapy sensitization

Tumor-associated macrophages (TAMs) and other myelomonocytic cells are implicated in regulating responsiveness to immunotherapies, including immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 axis. We have developed an ex vivo high-throughput approach to discover modulators of macrophage-mediated T cell suppression, which can improve clinical outcomes of ICIs. We screened 1,430 Food and Drug Administration (FDA)-approved small-molecule drugs using a co-culture assay employing bone-marrow-derived macrophages (BMDMs) and splenic-derived T cells. This identified 57 compounds that disrupted macrophage-mediated T cell suppression. Seven compounds exerted prominent synergistic T cell expansion activity when combined with αPD-L1. These include four COX1/2 inhibitors and two myeloid cell signaling inhibitors. We demonstrate that the use of cyclooxygenase (COX)1/2 inhibitors in combination with αPD-L1 decreases tumor growth kinetics and enhances overall survival in triple-negative breast cancer (TNBC) tumor models in a CD8+ T cell-dependent manner. Altogether, we present a rationalized approach for identifying compounds that synergize with ICI to potentially enhance therapeutic outcomes for patients with solid tumors.

Eliminating a barrier: Aiming at VISTA, reversing MDSC-mediated T cell suppression in the tumor microenvironment

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment by producing remarkable clinical outcomes for patients with various cancer types. However, only a subset of patients benefits from immunotherapeutic interventions due to the primary and acquired resistance to ICIs. Myeloid-derived suppressor cells (MDSCs) play a crucial role in creating an immunosuppressive tumor microenvironment (TME) and contribute to resistance to immunotherapy. V-domain Ig suppressor of T cell activation (VISTA), a negative immune checkpoint protein highly expressed on MDSCs, presents a promising target for overcoming resistance to current ICIs. This article provides an overview of the evidence supporting VISTA's role in regulating MDSCs in shaping the TME, thus offering insights into how to overcome immunotherapy resistance.

Myeloid‑derived suppressor cells: Key immunosuppressive regulators and therapeutic targets in colorectal cancer (Review)

Globally, colorectal cancer (CRC) is the third most common type of cancer. CRC has no apparent symptoms in the early stages of disease, and most patients receive a confirmed diagnosis in the middle or late disease stages. The incidence of CRC continues to increase, and the affected population tends to be younger. Therefore, determining how to achieve an early CRC diagnosis and treatment has become a top priority for prolonging patient survival. Myeloid‑derived suppressor cells (MDSCs) are a group of bone marrow‑derived immuno‑negative regulatory cells that are divided into two subpopulations, polymorphonuclear‑MDSCs and monocytic‑MDSCs, based on their phenotypic similarities to neutrophils and monocytes, respectively. These cells can inhibit the immune response and promote cancer cell metastasis in the tumour microenvironment (TME). A large aggregation of MDSCs in the TME is often a marker of cancer and a poor prognosis in inflammatory diseases of the intestine (such as colonic adenoma and ulcerative colitis). In the present review, the phenotypic classification of MDSCs in the CRC microenvironment are first discussed. Then, the amplification, role and metastatic mechanism of MDSCs in the CRC TME are described, focusing on genes, gene modifications, proteins and the intestinal microenvironment. Finally, the progress in CRC‑targeted therapies that aim to modulate the quantity, function and structure of MDSCs are summarized in the hope of identifying potential screening markers for CRC and improving CRC prognosis and therapeutic options.

A role of gut microbiota metabolites in HLA-E and NKG2 blockage immunotherapy against tumors: new insights for clinical application

One of major breakthroughs in immunotherapy against tumor is from blocking immune checkpoint molecules on tumor and reactive T cells. The development of CTLA-4 and PD-1 blockage antibodies has triggered to search for additional effective therapeutic strategies. This causes recent findings that blocking the interaction of checkpoint molecule NKG2A in NK and CD8 T cells with HLA-E in tumors is effective in defensing tumors. Interestingly, gut microbiota also affects this immune checkpoint immunotherapy against tumor. Gut microbiota such as bacteria can contribute to the regulation of host immune response and homeostasis. They not only promote the differentiation and function of immunosuppressive cells but also the inflammatory cells through the metabolites such as tryptophan (Trp) and bile acid (BA) metabolites as well as short chain fatty acids (SCFAs). These gut microbiota metabolites (GMMs) educated immune cells can affect the differentiation and function of effective CD8 and NK cells. Notably, these metabolites also directly affect the activity of CD8 and NK cells. Furthermore, the expression of CD94/NKG2A in the immune cells and/or their ligand HLA-E in the tumor cells is also regulated by gut microbiota associated immune factors. These findings offer new insights for the clinical application of gut microbiota in precise and/or personalized treatments of tumors. In this review, we will discuss the impacts of GMMs and GMM educated immune cells on the activity of effective CD8 and NK cells and the expression of CD94/NKG2A in immune cells and/or their ligand HLA-E in tumor cells.

Targeting amino acid-metabolizing enzymes for cancer immunotherapy

Despite the immune system's role in the detection and eradication of abnormal cells, cancer cells often evade elimination by exploitation of various immune escape mechanisms. Among these mechanisms is the ability of cancer cells to upregulate amino acid-metabolizing enzymes, or to induce these enzymes in tumor-infiltrating immunosuppressive cells. Amino acids are fundamental cellular nutrients required for a variety of physiological processes, and their inadequacy can severely impact immune cell function. Amino acid-derived metabolites can additionally dampen the anti-tumor immune response by means of their immunosuppressive activities, whilst some can also promote tumor growth directly. Based on their evident role in tumor immune escape, the amino acid-metabolizing enzymes glutaminase 1 (GLS1), arginase 1 (ARG1), inducible nitric oxide synthase (iNOS), indoleamine 2,3-dioxygenase 1 (IDO1), tryptophan 2,3-dioxygenase (TDO) and interleukin 4 induced 1 (IL4I1) each serve as a promising target for immunotherapeutic intervention. This review summarizes and discusses the involvement of these enzymes in cancer, their effect on the anti-tumor immune response and the recent progress made in the preclinical and clinical evaluation of inhibitors targeting these enzymes.

Tumor-stroma contact ratio - a novel predictive factor for tumor response to chemoradiotherapy in locally advanced oropharyngeal cancer

The growth pattern of oropharyngeal squamous cell carcinomas (OPSCC) varies from compact tumor cell aggregates to diffusely infiltrating tumor cell-clusters. The influence of the growth pattern on local tumor control and survival has been studied mainly for surgically treated oral cavity carcinomas on a visual basis. In this study, we used multiplex immunofluorescence staining (mIF) to examine the antigens pan-cytokeratin, p16INK4a, Ki67, CD271, PD-L1, and CD8 in pretherapeutic biopsies from 86 OPSCC. We introduce Tumor-stroma contact ratio (TSC), a novel parameter, to quantify the relationship between tumor cells in contact with the stromal surface and the total number of epithelial tumor cells. mIF tumor cores were analyzed at the single-cell level, and tumor-stromal contact area was quantified using the R package "Spatstat". TSC was correlated with the visually assessed invasion pattern by two independent investigators. Furthermore, TSC was analyzed in relation to clinical parameters and patient survival data to evaluate its potential prognostic significance. Higher TSC correlated with poor response to (chemo-)radiotherapy (r = 0.3, p < 0.01), and shorter overall (OS) and progression-free (PFS) survival (median OS: 13 vs 136 months, p < 0.0001; median PFS: 5 vs 85 months, p < 0.0001). Visual categorization of growth pattern according to established criteria of tumor aggressiveness showed interobserver variability increasing with more nuanced categories (2 categories: k = 0.7, 95 %-CI: 0.55 - 0.85; 4 categories k = 0.48, 95 %-CI: 0.35 - 0.61). In conclusion, TSC is an objective and reproducible computer-based parameter to quantify tumor-stroma contact area. We demonstrate its relevance for the response of oropharyngeal carcinomas to primary (chemo-)radiotherapy.

Targeting ROS in cancer: rationale and strategies

Reactive oxygen species (ROS) in biological systems are transient but essential molecules that are generated and eliminated by a complex set of delicately balanced molecular machineries. Disruption of redox homeostasis has been associated with various human diseases, especially cancer, in which increased ROS levels are thought to have a major role in tumour development and progression. As such, modulation of cellular redox status by targeting ROS and their regulatory machineries is considered a promising therapeutic strategy for cancer treatment. Recently, there has been major progress in this field, including the discovery of novel redox signalling pathways that affect the metabolism of tumour cells as well as immune cells in the tumour microenvironment, and the intriguing ROS regulation of biomolecular phase separation. Progress has also been made in exploring redox regulation in cancer stem cells, the role of ROS in determining cell fate and new anticancer agents that target ROS. This Review discusses these research developments and their implications for cancer therapy and drug discovery, as well as emerging concepts, paradoxes and future perspectives.

MYELOID-DERIVED SUPPRESSOR CELLS TWO YEARS AFTER HEPATITIS C VIRUS ERADICATION USING DIRECTLY ACTING ANTIVIRALS

BACKGROUND

Myeloid-derived suppressor cells (MDSCs) have immature morphology, relatively weak phagocytic activity, as well as some immunosuppressive functions. The capacity of MDSCs to inhibit T-cell-mediated immunological responses is their most notable functional characteristic. Down-regulating antitumor immune surveillance is one way that the expansion and activation of MDSCs contribute significantly to the occurrence and progression of tumors. Increased levels of MDSCs in patients with chronic hepatitis C virus (HCV) infection could suppress T-cell responses, promoting viral escape and hepatitis progression. This may make HCV-infected individuals more vulnerable to severe infections, hepatic and extra-hepatic tumors, and a diminished capacity to react to immunization. It is still unknown if effective HCV eradication with directly acting antivirals (DAAs) can restore immune functions and immune surveillance capacity.

OBJECTIVE

The purpose of this study was to observe the frequency of M-MDSCs (CD33+, CD11b+, and HLA-DR) in patients with a previous history of HCV, 2-3 years after virus eradication using DAA therapy.

METHODS

This study was conducted on 110 subjects: fifty-five subjects without liver cirrhosis who were treated with HCV using DAAs and attained SVR for a period of 2-3 years and 55 age- and gender-matched healthy controls. The study was conducted during the period from January to July 2022. Patients were recruited from the National Viral Hepatitis Treatment Unit, Alexandria University Hepatology outpatient clinic, and the Alexandria University Tropical Medicine outpatient clinic. The frequencies of MDSCs (CD33+CD11b + HLA-DR-) by flow cytometry were assessed.

RESULTS

Even after the virus had been eradicated for longer than two years, MDSC levels in HCV-treated individuals were found to be considerably higher. In the HCV-treated group, the median number of MDSCs was 5, with an interquartile range (IQR) of 3.79-7.69. In contrast, the median for the control group was 3.1, with an IQR of 1.4-3.2 (P˂0.001).

CONCLUSION

Successful DAA therapy leads to slow and partial immunological reconstitution, as demonstrated by the failure to attain normal levels of MDSC's 2 years after successful HCV eradication despite the normalization of laboratory parameters as well as the absence of liver fibrosis. The clinical implications of these findings should be thoroughly studied.

Advancements in microenvironment-based therapies: transforming the landscape of multiple myeloma treatment

Multiple myeloma (MM) is the most prevalent malignant monoclonal disease of plasma cells. There is mounting evidence that interactions with the bone marrow (BM) niche are essential for the differentiation, proliferation, survival, migration, and treatment resistance of myeloma cells. For this reason, gaining a deeper comprehension of how BM microenvironment compartments interact with myeloma cells may inspire new therapeutic ideas that enhance patient outcomes. This review will concentrate on the most recent findings regarding the mechanisms of interaction between microenvironment and MM and highlight research on treatment targeting the BM niche.

Plasmodium yoelii Infection Enhances the Expansion of Myeloid-Derived Suppressor Cells via JAK/STAT3 Pathway

Myeloid-derived suppressor cells (MDSCs), the negative immune regulators, have been demonstrated to be involved in immune responses to a variety of pathological conditions, such as tumors, chronic inflammation, and infectious diseases. However, the roles and mechanisms underlying the expansion of MDSCs in malaria remain unclear. In this study, the phenotypic and functional characteristics of splenic MDSCs during Plasmodium yoelii NSM infection are described. Furthermore, we provide compelling evidence that the sera from P. yoelii-infected C57BL/6 mice containing excess IL-6 and granulocyte-macrophage colony-stimulating factor promote the accumulation of MDSCs by inducing Bcl2 expression. Serum-induced MDSCs exert more potent suppressive effects on T cell responses than control MDSCs within both in vivo P. yoelii infection and in vitro serum-treated bone marrow cells experiments. Serum treatment increases the MDSC inhibitory effect, which is dependent on Arg1 expression. Moreover, mechanistic studies reveal that the serum effects are mediated by JAK/STAT3 signaling. By inhibiting STAT3 phosphorylation with the JAK inhibitor JSI-124, effects of serum on MDSCs are almost eliminated. In vivo depletion of MDSCs with anti-Gr-1 or 5-fluorouracil significantly reduces the parasitemia and promotes Th1 immune response in P. yoelii-infected C57BL/6 mice by upregulating IFN-γ expression. In summary, this study indicates that P. yoelii infection facilitates the accumulation and function of MDSCs by upregulating the expression of Bcl2 and Arg1 via JAK/STAT3 signaling pathway in vivo and in vitro. Manipulating the JAK/STAT3 signaling pathway or depleting MDSCs could be promising therapeutic interventions to treat malaria.

Platelet-derived TGF-β1 induces functional reprogramming of myeloid-derived suppressor cells in immune thrombocytopenia

ABSTRACT

Platelet α-granules are rich in transforming growth factor β1 (TGF-β1), which is associated with myeloid-derived suppressor cell (MDSC) biology. Responders to thrombopoietin receptor agonists (TPO-RAs) revealed a parallel increase in the number of both platelets and MDSCs. Here, anti-CD61 immune-sensitized splenocytes were transferred into severe combined immunodeficient mice to establish an active murine model of immune thrombocytopenia (ITP). Subsequently, we demonstrated that TPO-RAs augmented the inhibitory activities of MDSCs by arresting plasma cells differentiation, reducing Fas ligand expression on cytotoxic T cells, and rebalancing T-cell subsets. Mechanistically, transcriptome analysis confirmed the participation of TGF-β/Smad pathways in TPO-RA-corrected MDSCs, which was offset by Smad2/3 knockdown. In platelet TGF-β1-deficient mice, TPO-RA-induced amplification and enhanced suppressive capacity of MDSCs was waived. Furthermore, our retrospective data revealed that patients with ITP achieving complete platelet response showed superior long-term outcomes compared with those who only reach partial response. In conclusion, we demonstrate that platelet TGF-β1 induces the expansion and functional reprogramming of MDSCs via the TGF-β/Smad pathway. These data indicate that platelet recovery not only serves as an end point of treatment response but also paves the way for immune homeostasis in immune-mediated thrombocytopenia.

Role of antioxidants in modulating anti-tumor T cell immune resposne

It has been well established that in addition to oxygen's vital in cellular respiration, a disruption of oxygen balance can lead to increased stress and oxidative injury. Similarly, reduced oxygen during tumor proliferation and invasion generates a hypoxic tumor microenvironment, resulting in dysfunction of immune cells and providing a conducive milieu for tumors to adapt and grow. Strategies to improve the persistence tumor reactive T cells in the highly oxidative tumor environment are being pursued for enhancing immunotherapy outcomes. To this end, we have focused on various strategies that can help increase or maintain the antioxidant capacity of T cells, thus reducing their susceptibility to oxidative stress/damage. Herein we lay out an overview on the role of oxygen in T cell signaling and how pathways regulating oxidative stress or antioxidant signaling can be targeted to enhance immunotherapeutic approaches for cancer treatment.

Tumor microenvironment as niche constructed by cancer stem cells: Breaking the ecosystem to combat cancer

BACKGROUND

Cancer stem cells (CSCs) are a distinct subpopulation of cancer cells with the capacity to constantly self-renew and differentiate, and they are the main driver in the progression of cancer resistance and relapse. The tumor microenvironment (TME) constructed by CSCs is the "soil" adapted to tumor growth, helping CSCs evade immune killing, enhance their chemical resistance, and promote cancer progression.

AIM OF REVIEW

We aim to elaborate the tight connection between CSCs and immunosuppressive components of the TME. We attempt to summarize and provide a therapeutic strategy to eradicate CSCs based on the destruction of the tumor ecological niche.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review is focused on three main key concepts. First, we highlight that CSCs recruit and transform normal cells to construct the TME, which further provides ecological niche support for CSCs. Second, we describe the main characteristics of the immunosuppressive components of the TME, targeting strategies and summarize the progress of corresponding drugs in clinical trials. Third, we explore the multilevel insights of the TME to serve as an ecological niche for CSCs.

Shortwave-infrared-light-emitting probes for the in vivo tracking of cancer vaccines and the elicited immune responses

Tracking and imaging immune cells in vivo non-invasively would offer insights into the immune responses induced by vaccination. Here we report a cancer vaccine consisting of polymer-coated NaErF4/NaYF4 core-shell down-conversion nanoparticles emitting luminescence in the near-infrared spectral window IIb (1,500-1,700 nm in wavelength) and with surface-conjugated antigen (ovalbumin) and electrostatically complexed adjuvant (class-B cytosine-phosphate-guanine). Whole-body wide-field imaging of the subcutaneously injected vaccine in tumour-bearing mice revealed rapid migration of the nanoparticles to lymph nodes through lymphatic vessels, with two doses of the vaccine leading to the complete eradication of pre-existing tumours and to the prophylactic inhibition of tumour growth. The abundance of antigen-specific CD8+ T lymphocytes in the tumour microenvironment correlated with vaccine efficacy, as we show via continuous-wave imaging and lifetime imaging of two intravenously injected near-infrared-emitting probes (CD8+-T-cell-targeted NaYbF4/NaYF4 nanoparticles and H-2Kb/ovalbumin257-264 tetramer/PbS/CdS quantum dots) excited at different wavelengths, and by volumetrically visualizing the three nanoparticles via light-sheet microscopy with structured illumination. Nanoparticle-based vaccines and imaging probes emitting infrared light may facilitate the design and optimization of immunotherapies.

Myeloid-derived suppressor cells in peripheral blood as predictive biomarkers in patients with solid tumors undergoing immune checkpoint therapy: systematic review and meta-analysis

Background

Immunotherapeutic approaches, including immune checkpoint inhibitor (ICI) therapy, are increasingly recognized for their potential. Despite notable successes, patient responses to these treatments vary significantly. The absence of reliable predictive and prognostic biomarkers hampers the ability to foresee outcomes. This meta-analysis aims to evaluate the predictive significance of circulating myeloid-derived suppressor cells (MDSC) in patients with solid tumors undergoing ICI therapy, focusing on progression-free survival (PFS) and overall survival (OS).

Methods

A comprehensive literature search was performed across PubMed and EMBASE from January 2007 to November 2023, utilizing keywords related to MDSC and ICI. We extracted hazard ratios (HRs) and 95% confidence intervals (CIs) directly from the publications or calculated them based on the reported data. A hazard ratio greater than 1 indicated a beneficial effect of low MDSC levels. We assessed heterogeneity and effect size through subgroup analyses.

Results

Our search yielded 4,023 articles, of which 17 studies involving 1,035 patients were included. The analysis revealed that patients with lower levels of circulating MDSC experienced significantly improved OS (HR=2.13 [95% CI 1.51-2.99]) and PFS (HR=1.87 [95% CI 1.29-2.72]) in response to ICI therapy. Notably, heterogeneity across these outcomes was primarily attributed to differences in polymorphonuclear MDSC (PMN-MDSC) subpopulations and varying cutoff methodologies used in the studies. The monocytic MDSC (M-MDSC) subpopulation emerged as a consistent and significant prognostic marker across various subgroup analyses, including ethnicity, tumor type, ICI target, sample size, and cutoff methodology.

Conclusions

Our findings suggest that standardized assessment of MDSC, particularly M-MDSC, should be integral to ICI therapy strategies. These cells hold the promise of identifying patients at risk of poor response to ICI therapy, enabling tailored treatment approaches. Further research focusing on the standardization of markers and validation of cutoff methods is crucial for integrating MDSC into clinical practice.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023420095, identifier CRD42023420095.

Role of T cells in liver metastasis

The liver is a major metastatic site (organ) for gastrointestinal cancers (such as colorectal, gastric, and pancreatic cancers) as well as non-gastrointestinal cancers (such as lung, breast, and melanoma cancers). Due to the innate anatomical position of the liver, the apoptosis of T cells in the liver, the unique metabolic regulation of hepatocytes and other potential mechanisms, the liver tends to form an immunosuppressive microenvironment and subsequently form a pre-metastatic niche (PMN), which can promote metastasis and colonization by various tumor cells(TCs). As a result, the critical role of immunoresponse in liver based metastasis has become increasingly appreciated. T cells, a centrally important member of adaptive immune response, play a significant role in liver based metastases and clarifying the different roles of the various T cells subsets is important to guide future clinical treatment. In this review, we first introduce the predisposing factors and related mechanisms of liver metastasis (LM) before introducing the PMN and its transition to LM. Finally, we detail the role of different subsets of T cells in LM and advances in the management of LM in order to identify potential therapeutic targets for patients with LM.

Hepatic recruitment of myeloid-derived suppressor cells upon liver injury promotes both liver regeneration and fibrosis

BACKGROUND

The liver regeneration is a highly complicated process depending on the close cooperations between the hepatocytes and non-parenchymal cells involving various inflammatory cells. Here, we explored the role of myeloid-derived suppressor cells (MDSCs) in the processes of liver regeneration and liver fibrosis after liver injury.

METHODS

We established four liver injury models of mice including CCl4-induced liver injury model, bile duct ligation (BDL) model, concanavalin A (Con A)-induced hepatitis model, and lipopolysaccharide (LPS)-induced hepatitis model. The intrahepatic levels of MDSCs (CD11b+Gr-1+) after the liver injury were detected by flow cytometry. The effects of MDSCs on liver tissues were analyzed in the transwell co-culture system, in which the MDSCs cytokines including IL-10, VEGF, and TGF-β were measured by ELISA assay and followed by being blocked with specific antibodies.

RESULTS

The intrahepatic infiltrations of MDSCs with surface marker of CD11b+Gr-1+ remarkably increased after the establishment of four liver injury models. The blood served as the primary reservoir for hepatic recruitment of MDSCs during the liver injury, while the bone marrow appeared play a compensated role in increasing the number of MDSCs at the late stage of the inflammation. The recruited MDSCs in injured liver were mainly the M-MDSCs (CD11b+Ly6G-Ly6Chigh) featured by high expression levels of cytokines including IL-10, VEGF, and TGF-β. Co-culture of the liver tissues with MDSCs significantly promoted the proliferation of both hepatocytes and hepatic stellate cells (HSCs).

CONCLUSIONS

The dramatically and quickly infiltrated CD11b+Gr-1+ MDSCs in injured liver not only exerted pro-proliferative effects on hepatocytes, but also accounted for the activation of profibrotic HSCs.

β-Glucan Subverts the Function of Myeloid Cells in Neonates

β-Glucan is the main component of the cell wall of pathogen-associated molecular patterns (PAMPs) including various yeast, fungi, or certain bacteria. Previous reports demonstrated that β-glucan was widely investigated as a potent immunomodulators to stimulate innate and adaptive immune responses, which indicated that it could be recommended as an effective adjuvant in immunotherapy. However, the detailed effects of β-glucan on neonatal immunity are still largely unknown. Here, we found that β-glucan did not affect the frequencies and numbers of myeloid cells in the spleen and bone marrow from neonates. Functional assay revealed that β-glucan from neonates compromised the immunosuppressive function of immature myeloid cells, which were myeloid-derived suppressor cells (MDSCs). Flow cytometry or gene expression analysis revealed that β-glucan-derived polymorphonuclear (PMN)-MDSCs produced lower level of reactive oxygen species (ROS) and arginase-1 (Arg1) in neonatal mice. Furthermore, β-glucan administration significantly decreased the frequency and ROS level of PMN-MDSCs in vitro. These observations suggest that β-glucan facilitates the maturation of myeloid cells in early life, which may contribute to its beneficial effects against immune disorders later in life.

Understanding the immunosuppressive microenvironment of glioma: mechanistic insights and clinical perspectives

Glioblastoma (GBM), the predominant and primary malignant intracranial tumor, poses a formidable challenge due to its immunosuppressive microenvironment, thereby confounding conventional therapeutic interventions. Despite the established treatment regimen comprising surgical intervention, radiotherapy, temozolomide administration, and the exploration of emerging modalities such as immunotherapy and integration of medicine and engineering technology therapy, the efficacy of these approaches remains constrained, resulting in suboptimal prognostic outcomes. In recent years, intensive scrutiny of the inhibitory and immunosuppressive milieu within GBM has underscored the significance of cellular constituents of the GBM microenvironment and their interactions with malignant cells and neurons. Novel immune and targeted therapy strategies have emerged, offering promising avenues for advancing GBM treatment. One pivotal mechanism orchestrating immunosuppression in GBM involves the aggregation of myeloid-derived suppressor cells (MDSCs), glioma-associated macrophage/microglia (GAM), and regulatory T cells (Tregs). Among these, MDSCs, though constituting a minority (4-8%) of CD45+ cells in GBM, play a central component in fostering immune evasion and propelling tumor progression, angiogenesis, invasion, and metastasis. MDSCs deploy intricate immunosuppressive mechanisms that adapt to the dynamic tumor microenvironment (TME). Understanding the interplay between GBM and MDSCs provides a compelling basis for therapeutic interventions. This review seeks to elucidate the immune regulatory mechanisms inherent in the GBM microenvironment, explore existing therapeutic targets, and consolidate recent insights into MDSC induction and their contribution to GBM immunosuppression. Additionally, the review comprehensively surveys ongoing clinical trials and potential treatment strategies, envisioning a future where targeting MDSCs could reshape the immune landscape of GBM. Through the synergistic integration of immunotherapy with other therapeutic modalities, this approach can establish a multidisciplinary, multi-target paradigm, ultimately improving the prognosis and quality of life in patients with GBM.

The Role of Myeloid-Derived Suppressor Cells in Multiple Sclerosis and Its Animal Model

Myeloid-derived suppressor cells (MDSCs), a heterogeneous cell population that consists of mostly immature myeloid cells, are immunoregulatory cells mainly characterized by their suppressive functions. Emerging findings have revealed the involvement of MDSCs in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). MS is an autoimmune and degenerative disease of the central nervous system characterized by demyelination, axon loss, and inflammation. Studies have reported accumulation of MDSCs in inflamed tissues and lymphoid organs of MS patients and EAE mice, and these cells display dual functions in EAE. However, the contribution of MDSCs to MS/EAE pathogenesis remains unclear. This review aims to summarize our current understanding of MDSC subsets and their possible roles in MS/EAE pathogenesis. We also discuss the potential utility and associated obstacles in employing MDSCs as biomarkers and cell-based therapies for MS.

The role of tumor-associated macrophages in tumor immune evasion

BACKGROUND

Tumor growth is closely linked to the activities of various cells in the tumor microenvironment (TME), particularly immune cells. During tumor progression, circulating monocytes and macrophages are recruited, altering the TME and accelerating growth. These macrophages adjust their functions in response to signals from tumor and stromal cells. Tumor-associated macrophages (TAMs), similar to M2 macrophages, are key regulators in the TME.

METHODS

We review the origins, characteristics, and functions of TAMs within the TME. This analysis includes the mechanisms through which TAMs facilitate immune evasion and promote tumor metastasis. Additionally, we explore potential therapeutic strategies that target TAMs.

RESULTS

TAMs are instrumental in mediating tumor immune evasion and malignant behaviors. They release cytokines that inhibit effector immune cells and attract additional immunosuppressive cells to the TME. TAMs primarily target effector T cells, inducing exhaustion directly, influencing activity indirectly through cellular interactions, or suppressing through immune checkpoints. Additionally, TAMs are directly involved in tumor proliferation, angiogenesis, invasion, and metastasis. Developing innovative tumor-targeted therapies and immunotherapeutic strategies is currently a promising focus in oncology. Given the pivotal role of TAMs in immune evasion, several therapeutic approaches have been devised to target them. These include leveraging epigenetics, metabolic reprogramming, and cellular engineering to repolarize TAMs, inhibiting their recruitment and activity, and using TAMs as drug delivery vehicles. Although some of these strategies remain distant from clinical application, we believe that future therapies targeting TAMs will offer significant benefits to cancer patients.

Key players of immunosuppression in epithelial malignancies: Tumor-infiltrating myeloid cells and γδ T cells

BACKGROUND

The tumor microenvironment of solid tumors governs the differentiation of otherwise non-immunosuppressive macrophages and gamma delta (γδ) T cells into strong immunosuppressors while promoting suppressive abilities of known immunosuppressors such as myeloid-derived suppressor cells (MDSCs) upon infiltration into the tumor beds.

RECENT FINDINGS

In epithelial malignancies, tumor-associated macrophages (TAMs), precursor monocytic MDSCs (M-MDSCs), and gamma delta (γδ) T cells often acquire strong immunosuppressive abilities that dampen spontaneous immune responses by tumor-infiltrating T cells and B lymphocytes against cancer. Both M-MDSCs and γδ T cells have been associated with worse prognosis for multiple epithelial cancers.

CONCLUSION

Here we discuss recent discoveries on how tumor-associated macrophages and precursor M-MDSCs as well as tumor associated-γδ T cells acquire immunosuppressive abilities in the tumor beds, promote cancer metastasis, and perspectives on how possible novel interventions could restore the effective adaptive immune responses in epithelial cancers.

Radiation Therapy and Myeloid-Derived Suppressor Cells: Breaking Down Their Cancerous Partnership

Radiation therapy (RT) has been a primary treatment modality in cancer for decades. Increasing evidence suggests that RT can induce an immunosuppressive shift via upregulation of cells such as tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs). MDSCs inhibit antitumor immunity through potent immunosuppressive mechanisms and have the potential to be crucial tools for cancer prognosis and treatment. MDSCs interact with many different pathways, desensitizing tumor tissue and interacting with tumor cells to promote therapeutic resistance. Vascular damage induced by RT triggers an inflammatory signaling cascade and potentiates hypoxia in the tumor microenvironment (TME). RT can also drastically modify cytokine and chemokine signaling in the TME to promote the accumulation of MDSCs. RT activation of the cGAS-STING cytosolic DNA sensing pathway recruits MDSCs through a CCR2-mediated mechanism, inhibiting the production of type 1 interferons and hampering antitumor activity and immune surveillance in the TME. The upregulation of hypoxia-inducible factor-1 and vascular endothelial growth factor mobilizes MDSCs to the TME. After recruitment, MDSCs promote immunosuppression by releasing reactive oxygen species and upregulating nitric oxide production through inducible nitric oxide synthase expression to inhibit cytotoxic activity. Overexpression of arginase-1 on subsets of MDSCs degrades L-arginine and downregulates CD3ζ, inhibiting T-cell receptor reactivity. This review explains how radiation promotes tumor resistance through activation of immunosuppressive MDSCs in the TME and discusses current research targeting MDSCs, which could serve as a promising clinical treatment strategy in the future.