Polymorphonuclear Myeloid-Derived Suppressor Cells Are Abundant in Peripheral Blood of Cancer Patients and Suppress Natural Killer Cell Anti-Tumor Activity

Exploring the role of the immune microenvironment in hepatocellular carcinoma: Implications for immunotherapy and drug resistance

Hepatocellular carcinoma (HCC), the most common type of liver tumor, is a leading cause of cancer-related deaths, and the incidence of liver cancer is still increasing worldwide. Curative hepatectomy or liver transplantation is only indicated for a small population of patients with early-stage HCC. However, most patients with HCC are not candidates for radical resection due to disease progression, leading to the choice of the conventional tyrosine kinase inhibitor drug sorafenib as first-line treatment. In the past few years, immunotherapy, mainly immune checkpoint inhibitors (ICIs), has revolutionized the clinical strategy for HCC. Combination therapy with ICIs has proven more effective than sorafenib, and clinical trials have been conducted to apply these therapies to patients. Despite significant progress in immunotherapy, the molecular mechanisms behind it remain unclear, and immune resistance is often challenging to overcome. Several studies have pointed out that the complex intercellular communication network in the immune microenvironment of HCC regulates tumor escape and drug resistance to immune response. This underscores the urgent need to analyze the immune microenvironment of HCC. This review describes the immunosuppressive cell populations in the immune microenvironment of HCC, as well as the related clinical trials, aiming to provide insights for the next generation of precision immunotherapy.

Comprehensive approach to cancer immunotherapy - Simultaneous targeting of myeloid-derived suppressor cells and cancer cells with AFP conjugates

The immune system plays a pivotal role in combating diseases, including cancer, with monocytes emerging as key regulators of immune response dynamics. This article describes a novel strategy for cancer treatment centered on depleting myeloid-derived suppressor cells (MDSCs), to enhance the overall immune response while simultaneously targeting cancer cells directly. Alpha-fetoprotein (AFP) is an oncofetal protein that plays an important role in delivering nutrients to immature monocytes, embryonic, and cancer cells in a targeted manner. AFP can be repurposed, making it a vehicle for delivering toxins, rather than nutrients to kill cancer cells and deplete MDSCs in the tumor microenvironment (TME). Depleting monocytes not only stimulates the immune system but also improves the lymphocyte-to-monocyte ratio (LMR), often low in cancer patients. AFP combined with cytotoxic drugs, offers dual benefit-immune stimulation and targeted chemotherapy. Studies in xenograft models demonstrated high efficacy and safety of AFP-toxin conjugates, surpassing conventional targeted chemotherapy. Such conjugates have also been reported to provide superior efficacy and safety in cancer patients compared to chemotherapy. This approach, using AFP conjugated with toxins, either covalently or non-covalently, presents a safe and highly effective option for cancer immuno/chemotherapy.

Human NK cells and cancer

The long story of NK cells started about 50 y ago with the first demonstration of a natural cytotoxic activity within an undefined subset of circulating leukocytes, has involved an ever-growing number of researchers, fascinated by the apparently easy-to-reach aim of getting a "universal anti-tumor immune tool". In fact, in spite of the impressive progress obtained in the first decades, these cells proved far more complex than expected and, paradoxically, the accumulating findings have continuously moved forward the attainment of a complete control of their function for immunotherapy. The refined studies of these latter years have indicated that NK cells can epigenetically calibrate their functional potential, in response to specific environmental contexts, giving rise to extraordinarily variegated subpopulations, comprehensive of memory-like cells, tissue-resident cells, or cells in various differentiation stages, or distinct functional states. In addition, NK cells can adapt their activity in response to a complex body of signals, spanning from the interaction with either suppressive or stimulating cells (myeloid-derived suppressor cells or dendritic cells, respectively) to the engagement of various receptors (specific for immune checkpoints, cytokines, tumor/viral ligands, or mediating antibody-dependent cell-mediated cytotoxicity). According to this picture, the idea of an easy and generalized exploitation of NK cells is changing, and the way is opening toward new carefully designed, combined and personalized therapeutic strategies, also based on the use of genetically modified NK cells and stimuli capable of strengthening and redirecting their effector functions against cancer.

Causal relationships between immune cell phenotypes and lung adenocarcinoma: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Lung adenocarcinoma (LUAD) is the most common type of lung cancer and closely associated with the immune system. Emerging evidence suggests that blood immune cell phenotypes in patients with LUAD may undergo alterations. Nevertheless, the limited amount of relevant research makes it difficult to understand the causal links between LUAD and changes in the immune cells. This study aimed to reveal the potential causal relationships between 731 immune cell phenotypes and LUAD.

METHODS

A bidirectional two-sample Mendelian randomization (MR) analysis was used to clarify causal relationships. Four types of immune phenotypes, absolute cell counts, relative cell counts, median fluorescence intensities (MFIs) of surface antigens, and morphological parameters, were investigated in this study. Heterogeneity tests, horizontal pleiotropy tests, and leave-one-out analyses were performed to validate the reliability of our study.

RESULTS

A total of 26 immune cell characteristics were identified as contributing to the occurrence of LUAD. Memory B cells, IgD-CD38br cells, CD4+ regulatory T cells (Tregs), and plasmacytoid dendritic cells (DCs) may play a role in the development of LUAD. Through reverse MR, our study discovered that the presence of LUAD also induced changes in the expression levels of 16 immune cell traits involving specific surface markers and various types of immune cells, some of which pertain to antigen presentation and immune activation processes.

CONCLUSION

Our study demonstrated causal links between several immune cell phenotypes and LUAD, thereby providing indications of the potentially oncogenic physiological state and early screening biomarkers for future research.

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.

Exosome as a crucial communicator between tumor microenvironment and gastric cancer (Review)

Gastric cancer is one of the most common malignancies and has relatively high morbidity and mortality rates. Exosomes are nanoscale extracellular vesicles that originate from a diverse array of cells and may be found throughout various bodily fluids. These vesicles are endogenous nanocarriers in their natural state with the unique ability to transport lipids, proteins, DNA and RNA. Exosomes contain DNA, RNA, proteins, lipids and other bioactive components that have crucial roles in the transmission of information and regulation of cell activities in gastric cancer. This paper begins with an exploration of the composition, formation and release mechanisms of exosomes. Subsequently, the role of exosomes in the tumor microenvironment is reviewed in terms of the immune cell population, nonimmune cell population and other factors. Finally, the current status and challenges of exosome‑based research on the progression, diagnosis and therapeutic methods of gastric cancer are summarized. This holistic review offers insight that may guide future research directions for exosomes and potentially pave the way for novel therapeutic interventions in the management of gastric cancer.

Myeloid-derived suppressor cells in cancer and cancer therapy

Anticancer agents continue to dominate the list of newly approved drugs, approximately half of which are immunotherapies. This trend illustrates the considerable promise of cancer treatments that modulate the immune system. However, the immune system is complex and dynamic, and can have both tumour-suppressive and tumour-promoting effects. Understanding the full range of immune modulation in cancer is crucial to identifying more effective treatment strategies. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of myeloid cells that develop in association with chronic inflammation, which is a hallmark of cancer. Indeed, MDSCs accumulate in the tumour microenvironment, where they strongly inhibit anticancer functions of T cells and natural killer cells and exert a variety of other tumour-promoting effects. Emerging evidence indicates that MDSCs also contribute to resistance to cancer treatments, particularly immunotherapies. Conversely, treatment approaches designed to eliminate cancer cells can have important additional effects on MDSC function, which can be either positive or negative. In this Review, we discuss the interplay between MDSCs and various other cell types found in tumours as well as the mechanisms by which MDSCs promote tumour progression. We also discuss the relevance and implications of MDSCs for cancer therapy.

[Research Progress of Granulocytic Myeloid-derived Suppressor Cells in Non-small Cell Lung Cancer]

Granulocytic myeloid-derived suppressor cells (G-MDSCs) are one of the main subgroups of MDSCs, which are widely enriched in most cancers. It can inhibit the killing function of T-lymphocyte through the expression of arginase-1 (Arg-1) and reactive oxygen species (ROS), reshape the tumor immune microenvironment, and promote the occurrence and development of tumors. In recent years, more and more studies have found that G-MDSCs are significantly correlated with the prognosis and immunotherapy efficacy of patients with non-small cell lung cancer, and the use of drugs specifically targeting the recruitment, differentiation and function of G-MDSCs can effectively inhibit tumor progression. This article reviews the immunosuppressive effect of G-MDSCs in non-small cell lung cancer and the progress of related pathway targeting drugs.
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The Role of Neutrophil in COVID-19: Positive or Negative

BACKGROUND

Neutrophils are the first line of defense against pathogens. They are divided into multiple subpopulations during development and kill pathogens through various mechanisms. Neutrophils are considered one of the markers of severe COVID-19.

SUMMARY

In-depth research has revealed that neutrophil subpopulations have multiple complex functions. Different subsets of neutrophils play an important role in the progression of COVID-19.

KEY MESSAGES

In this review, we provide a detailed overview of the developmental processes of neutrophils at different stages and their recruitment and activation after SARS-CoV-2 infection, aiming to elucidate the changes in neutrophil subpopulations, characteristics, and functions after infection and provide a reference for mechanistic research on neutrophil subpopulations in the context of SARS-CoV-2 infection. In addition, we have also summarized research progress on potential targeted drugs for neutrophil immunotherapy, hoping to provide information that aids the development of therapeutic drugs for the clinical treatment of critically ill COVID-19 patients.

Landscape of tumor and immune system cells-derived exosomes in lung cancer: mediators of antitumor immunity regulation

The immune system plays a critical role in cancer, including lung cancer, which is the leading cause of cancer-related deaths worldwide. Immunotherapy, particularly immune checkpoint blockade, has revolutionized the treatment of lung cancer, but a large subset of patients either do not respond or develop resistance. Exosomes, essential mediators of cell-to-cell communication, exert a profound influence on the tumor microenvironment and the interplay between cancer and the immune system. This review focuses on the role of tumor-derived exosomes and immune cells-derived exosomes in the crosstalk between these cell types, influencing the initiation and progression of lung cancer. Depending on their cell of origin and microenvironment, exosomes can contain immunosuppressive or immunostimulatory molecules that can either promote or inhibit tumor growth, thus playing a dual role in the disease. Furthermore, the use of exosomes in lung cancer immunotherapy is discussed. Their potential applications as cell-free vaccines and drug delivery systems make them an attractive option for lung cancer treatment. Additionally, exosomal proteins and RNAs emerge as promising biomarkers that could be employed for the prediction, diagnosis, prognosis and monitoring of the disease. In summary, this review assesses the relationship between exosomes, lung cancer, and the immune system, shedding light on their potential clinical applications and future perspectives.

Remodeling the tumor microenvironment to overcome treatment resistance in HPV-negative head and neck cancer

Despite intensive efforts and refined techniques, overall survival in HPV-negative head and neck cancer remains poor. Robust immune priming is required to elicit a strong and durable antitumor immune response in immunologically cold and excluded tumors like HPV-negative head and neck cancer. This review highlights how the tumor microenvironment could be affected by different immune and stromal cell types, weighs the need to integrate metabolic regulation of the tumor microenvironment into cancer treatment strategies and summarizes the emerging clinical applicability of personalized immunotherapeutic strategies in HPV-negative head and neck cancer.

Myeloid-Derived Suppressor Cells (MDSC) in Melanoma Patients Treated with Anti-PD-1 Immunotherapy

Myeloid-derived suppressor cells (MDSC) are a subset of immature myeloid cells with suppressive activity well described in the context of cancer. They inhibit anti-tumour immunity, promote metastasis formation and can lead to immune therapy resistance. In a retrospective study, blood probes of 46 advanced melanoma patients were analysed before the first administration of anti-PD-1 immunotherapy and in the third month of treatment for MDSC, immature monocytic (ImMC), monocytic MDSC (MoMDSC) and granulocytic MDSC (GrMDSC) by multi-channel flow cytometry. Cell frequencies were correlated with response to immunotherapy, progression-free survival (PFS) and lactate dehydrogenase (LDH) serum level. Responders to anti-PD-1 therapy had higher MoMDSC levels (4.1 ± 1.2%) compared to non-responders (3.0 ± 1.2%) (p = 0.0333) before the first administration of anti-PD-1. No significant changes in MDSCs frequencies were observed in the groups of patients before and in the third month of therapy. The cut-off values of MDSCs, MoMDSCs, GrMDSCs and ImMCs for favourable 2- and 3-year PFS were established. Elevated LDH level is a negative prognostic factor of response to the treatment and is related to an elevated ratio of GrMDSCs and ImMCs level compared to patients' LDH level below the cut-off. Our data may provide a new perspective for more careful consideration of MDSCs, and specially MoMDSCs, as a tool for monitoring the immune status of melanoma patients. Changes in MDSC levels may have a potential prognostic value, however a correlation with other parameters must be established.

Exosomes and cancer immunotherapy: A review of recent cancer research

As phospholipid extracellular vesicles (EVs) secreted by various cells, exosomes contain non-coding RNA (ncRNA), mRNA, DNA fragments, lipids, and proteins, which are essential for intercellular communication. Several types of cells can secrete exosomes that contribute to cancer initiation and progression. Cancer cells and the immune microenvironment interact and restrict each other. Tumor-derived exosomes (TDEs) have become essential players in this balance because they carry information from the original cancer cells and express complexes of MHC class I/II epitopes and costimulatory molecules. In the present study, we aimed to identify potential targets for exosome therapy by examining the specific expression and mechanism of exosomes derived from cancer cells. We introduced TDEs and explored their role in different tumor immune microenvironment (TIME), with a particular emphasis on gastrointestinal cancers, before briefly describing the therapeutic strategies of exosomes in cancer immune-related therapy.

Strategies to overcome myeloid cell induced immune suppression in the tumor microenvironment

Cancer progression and metastasis due to tumor immune evasion and drug resistance is strongly associated with immune suppressive cellular responses, particularly in the case of metastatic tumors. The myeloid cell component plays a key role within the tumor microenvironment (TME) and disrupts both adaptive and innate immune cell responses leading to loss of tumor control. Therefore, strategies to eliminate or modulate the myeloid cell compartment of the TME are increasingly attractive to non-specifically increase anti-tumoral immunity and enhance existing immunotherapies. This review covers current strategies targeting myeloid suppressor cells in the TME to enhance anti-tumoral immunity, including strategies that target chemokine receptors to deplete selected immune suppressive myeloid cells and relieve the inhibition imposed on the effector arms of adaptive immunity. Remodeling the TME can in turn improve the activity of other immunotherapies such as checkpoint blockade and adoptive T cell therapies in immunologically "cold" tumors. When possible, in this review, we have provided evidence and outcomes from recent or current clinical trials evaluating the effectiveness of the specific strategies used to target myeloid cells in the TME. The review seeks to provide a broad overview of how myeloid cell targeting can become a key foundational approach to an overall strategy for improving tumor responses to immunotherapy.

Neuroblastoma Tumor-Associated Mesenchymal Stromal Cells Regulate the Cytolytic Functions of NK Cells

Neuroblastoma tumor-associated mesenchymal stromal cells (NB-TA-MSC) have been extensively characterized for their pro-tumorigenic properties, while their immunosuppressive potential, especially against NK cells, has not been thoroughly investigated. Herein, we study the immune-regulatory potential of six primary young and senescent NB-TA-MSC on NK cell function. Young cells display a phenotype (CD105+/CD90+/CD73+/CD29+/CD146+) typical of MSC cells and, in addition, express high levels of immunomodulatory molecules (MHC-I, PDL-1 and PDL-2 and transcriptional-co-activator WWTR1), able to hinder NK cell activity. Notably, four of them express the neuroblastoma marker GD2, the most common target for NB immunotherapy. From a functional point of view, young NB-TA-MSC, contrary to the senescent ones, are resistant to activated NK cell-mediated lysis, but this behavior is overcome using anti-CD105 antibody TRC105 that activates antibody-dependent cell-mediated cytotoxicity. In addition, proliferating NB-TA-MSC, but not the senescent ones, after six days of co-culture, inhibit proliferation, expression of activating receptors and cytolytic activity of freshly isolated NK. Inhibitors of the soluble immunosuppressive factors L-kynurenine and prostaglandin E2 efficiently counteract this latter effect. Our data highlight the presence of phenotypically heterogeneous NB-TA-MSC displaying potent immunoregulatory properties towards NK cells, whose inhibition could be mandatory to improve the antitumor efficacy of targeted immunotherapy.

Counteracting Immunosuppression in the Tumor Microenvironment by Oncolytic Newcastle Disease Virus and Cellular Immunotherapy

An apparent paradox exists between the evidence for spontaneous systemic T cell- mediated anti-tumor immune responses in cancer patients, observed particularly in their bone marrow, and local tumor growth in the periphery. This phenomenon, known as "concomitant immunity" suggests that the local tumor and its tumor microenvironment (TME) prevent systemic antitumor immunity to become effective. Oncolytic Newcastle disease virus (NDV), an agent with inherent anti-neoplastic and immune stimulatory properties, is capable of breaking therapy resistance and immunosuppression. This review updates latest information about immunosuppression by the TME and discusses mechanisms of how oncolytic viruses, in particular NDV, and cellular immunotherapy can counteract the immunosuppressive effect of the TME. With regard to cellular immunotherapy, the review presents pre-clinical studies of post-operative active-specific immunotherapy and of adoptive T cell-mediated therapy in immunocompetent mice. Memory T cell (MTC) transfer in tumor challenged T cell-deficient nu/nu mice demonstrates longevity and functionality of these cells. Graft-versus-leukemia (GvL) studies in mice demonstrate complete remission of late-stage disease including metastases and cachexia. T cell based immunotherapy studies with human cells in human tumor xenotransplanted NOD/SCID mice demonstrate superiority of bone marrow-derived as compared to blood-derived MTCs. Results from clinical studies presented include vaccination studies using two different types of NDV-modified cancer vaccine and a pilot adoptive T-cell mediated therapy study using re-activated bone marrow-derived cancer-reactive MTCs. As an example for what can be expected from clinical immunotherapy against tumors with an immunosuppressive TME, results from vaccination studies are presented from the aggressive brain tumor glioblastoma multiforme. The last decades of basic research in virology, oncology and immunology can be considered as a success story. Based on discoveries of these research areas, translational research and clinical studies have changed the way of treatment of cancer by introducing and including immunotherapy.

High Neutrophil-to-Lymphocyte Ratio Facilitates Cancer Growth-Currently Marketed Drugs Tadalafil, Isotretinoin, Colchicine, and Omega-3 to Reduce It: The TICO Regimen

Simple Summary

Several elements that are composed of, or related to, neutrophils, have been shown to inhibit strong immune responses to cancer and promote cancers’ growth. This paper presents the collected data showing these elements and how their coordinated actions as an ensemble facilitate growth in the common cancers. The paper goes on to present a drug regimen, TICO, designed to reduce the cancer growth enhancing effects of the neutrophil related elements. TICO uses four already marketed, readily available generic drugs, repurposed to inhibit neutrophil centered growth facilitation of cancer.

Abstract

This paper presents remarkably uniform data showing that higher NLR is a robust prognostic indicator of shorter overall survival across the common metastatic cancers. Myeloid derived suppressor cells, the NLRP3 inflammasome, neutrophil extracellular traps, and absolute neutrophil count tend to all be directly related to the NLR. They, individually and as an ensemble, contribute to cancer growth and metastasis. The multidrug regimen presented in this paper, TICO, was designed to decrease the NLR with potential to also reduce the other neutrophil related elements favoring malignant growth. TICO is comprised of already marketed generic drugs: the phosphodiesterase 5 inhibitor tadalafil, used to treat inadequate erections; isotretinoin, the retinoid used for acne treatment; colchicine, a standard gout (podagra) treatment; and the common fish oil supplement omega-3 polyunsaturated fatty acids. These individually impose low side effect burdens. The drugs of TICO are old, cheap, well known, and available worldwide. They all have evidence of lowering the NLR or the growth contributing elements related to the NLR when clinically used in general medicine as reviewed in this paper.

Circulating tumor cell-blood cell crosstalk: Biology and clinical relevance

Circulating tumor cells (CTCs) are the seeds of distant metastasis, and the number of CTCs detected in the blood of cancer patients is associated with a worse prognosis. CTCs face critical challenges for their survival in circulation, such as anoikis, shearing forces, and immune surveillance. Thus, understanding the mechanisms and interactions of CTCs within the blood microenvironment is crucial for better understanding of metastatic progression and the development of novel treatment strategies. CTCs interact with different hematopoietic cells, such as platelets, red blood cells, neutrophils, macrophages, natural killer (NK) cells, lymphocytes, endothelial cells, and cancer-associated fibroblasts, which can affect CTC survival in blood. This interaction may take place either via direct cell-cell contact or through secreted molecules. Here, we review interactions of CTCs with blood cells and discuss the potential clinical relevance of these interactions as biomarkers or as targets for anti-metastatic therapies.

In vitro preliminary study on different anti-PD-1 antibody concentrations on T cells activation

Lung adenocarcinoma predominates among diagnosed nonsmall cell lung cancer subtypes in nonsmokers. The introduction of immune checkpoint inhibitors into clinical practice offered patients prolonged progression-free survival and overall survival times. However, the results demonstrate that the benefits do not apply to all patients. Nivolumab is a monoclonal antibody against the PD-1 protein expressed mainly on T lymphocytes and is widely used in cancer therapy in different settings. Tumor cells often express the PD-L1 molecule and can effectively block the action of PD-1-positive lymphocytes. A body of knowledge regarding the high expression of PD-L1 on tumor cells highlights that it does not always correlate with the effectiveness of anti-PD-1 therapy. The side effects of the therapy also constitute a significant issue. These side effects can occur at any time during anti-PD-1 treatment and lead to discontinuation and even the death of the patient. In these situations, it is possible to delay the dosage. Nevertheless, unfortunately, it is not possible to reduce the dose of anti-PD-1 antibody, which would undoubtedly minimize side effects, leaving the patient's immune system active. In our preliminary study, we analyzed the effect of different concentrations of nivolumab on the functioning of T lymphocytes. Activation and proliferation markers were investigated on T cells after being cultured with antigen-stimulated autologous dendritic cells. This process may indicate an appropriate concentration of nivolumab, which shows clinical activity with minimal side effects.

Managing the TME to improve the efficacy of cancer therapy

The tumor microenvironment (TME) influences tumor growth, metastatic spread and response to treatment. Often immunosuppression, mediated by the TME, impairs a beneficial response. The complexity of the tumor composition challenges our abilities to design new and more effective therapies. Going forward we will need to 'manage' the content and or functionality of the TME to improve treatment outcomes. Currently, several different kinds of treatments are available to patients with cancer: there are the traditional approaches of chemotherapy, radiation and surgery; there are targeted agents that inhibit kinases associated with oncogenic pathways; there are monoclonal antibodies that target surface antigens often delivering toxic payloads or cells and finally there are antibodies and biologics that seek to overcome the immunosuppression caused by elements within the TME. How each of these therapies interact with the TME is currently under intense and widespread investigation. In this review we describe how the TME and its immunosuppressive components can influence both tumor progression and response to treatment focusing on three particular tumor types, classic Hodgkin Lymphoma (cHL), Pancreatic Ductal Adenocarcinoma (PDAC) and Glioblastoma Multiforme (GBM). And, finally, we offer five approaches to manipulate or manage the TME to improve outcomes for cancer patients.