Neutrophil degranulation and immunosuppression in patients with GBM: restoration of cellular immune function by targeting arginase I

Recent advances in biomimetic strategies for the immunotherapy of glioblastoma

Immunotherapy is regarded as one of the most promising approaches for treating tumors, with a multitude of immunotherapeutic thoughts currently under consideration for the lethal glioblastoma (GBM). However, issues with immunotherapeutic agents, such as limited in vivo stability, poor blood-brain barrier (BBB) penetration, insufficient GBM targeting, and represented monotherapy, have hindered the success of immunotherapeutic interventions. Moreover, even with the aid of conventional drug delivery systems, outcomes remain suboptimal. Biomimetic strategies seek to overcome these formidable drug delivery challenges by emulating nature's intelligent structures and functions. Leveraging the variety of biological structures and functions, biomimetic drug delivery systems afford a versatile platform with enhanced biocompatibility for the co-delivery of diverse immunotherapeutic agents. Moreover, their inherent capacity to traverse the BBB and home in on GBM holds promise for augmenting the efficacy of GBM immunotherapy. Thus, this review begins by revisiting the various thoughts and agents on immunotherapy for GBM. Then, the barriers to successful GBM immunotherapy are analyzed, and the corresponding biomimetic strategies are explored from the perspective of function and structure. Finally, the clinical translation's current state and prospects of biomimetic strategy are addressed. This review aspires to provide fresh perspectives on the advancement of immunotherapy for GBM.

The roles of arginases and arginine in immunity

Arginase activity and arginine metabolism in immune cells have important consequences for health and disease. Their dysregulation is commonly observed in cancer, autoimmune disorders and infectious diseases. Following the initial description of a role for arginase in the dysfunction of T cells mounting an antitumour response, numerous studies have broadened our understanding of the regulation and expression of arginases and their integration with other metabolic pathways. Here, we highlight the differences in arginase compartmentalization and storage between humans and rodents that should be taken into consideration when assessing the effects of arginase activity. We detail the roles of arginases, arginine and its metabolites in immune cells and their effects in the context of cancer, autoimmunity and infectious disease. Finally, we explore potential therapeutic strategies targeting arginases and arginine.

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.

An Update on the Clinical Status, Challenges, and Future Directions of Oncolytic Virotherapy for Malignant Gliomas

OPINION STATEMENT

Malignant gliomas are common central nervous system tumors that pose a significant clinical challenge due to the lack of effective treatments. Glioblastoma (GBM), a grade 4 malignant glioma, is the most prevalent primary malignant brain tumor and is associated with poor prognosis. Current clinical trials are exploring various strategies to combat GBM, with oncolytic viruses (OVs) appearing particularly promising. In addition to ongoing and recently completed clinical trials, one OV (Teserpaturev, Delytact®) received provisional approval for GBM treatment in Japan. OVs are designed to selectively target and eliminate cancer cells while promoting changes in the tumor microenvironment that can trigger and support long-lasting anti-tumor immunity. OVs offer the potential to remodel the tumor microenvironment and reverse systemic immune exhaustion. Additionally, an increasing number of OVs are armed with immunomodulatory payloads or combined with immunotherapy approaches in an effort to promote anti-tumor responses in a tumor-targeted manner. Recently completed oncolytic virotherapy trials can guide the way for future treatment individualization through patient preselection, enhancing the likelihood of achieving the highest possible clinical success. These trials also offer valuable insight into the numerous challenges inherent in malignant glioma treatment, some of which OVs can help overcome.

Neutrophils in glioma microenvironment: from immune function to immunotherapy

Glioma is a malignant tumor of the central nervous system (CNS). Currently, effective treatment options for gliomas are still lacking. Neutrophils, as an important member of the tumor microenvironment (TME), are widely distributed in circulation. Recently, the discovery of cranial-meningeal channels and intracranial lymphatic vessels has provided new insights into the origins of neutrophils in the CNS. Neutrophils in the brain may originate more from the skull and adjacent vertebral bone marrow. They cross the blood-brain barrier (BBB) under the action of chemokines and enter the brain parenchyma, subsequently migrating to the glioma TME and undergoing phenotypic changes upon contact with tumor cells. Under glycolytic metabolism model, neutrophils show complex and dual functions in different stages of cancer progression, including participation in the malignant progression, immune suppression, and anti-tumor effects of gliomas. Additionally, neutrophils in the TME interact with other immune cells, playing a crucial role in cancer immunotherapy. Targeting neutrophils may be a novel generation of immunotherapy and improve the efficacy of cancer treatments. This article reviews the molecular mechanisms of neutrophils infiltrating the central nervous system from the external environment, detailing the origin, functions, classifications, and targeted therapies of neutrophils in the context of glioma.

Present and Future of Immunotherapy in Patients With Glioblastoma: Limitations and Opportunities

Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor. Standard therapies, including surgical resection, chemoradiation, and tumor treating fields, have not resulted in major improvements in the survival outcomes of patients with GBM. The lack of effective strategies has led to an increasing interest in immunotherapic approaches, considering the success in other solid tumors. However, GBM is a highly immunosuppressive tumor, as documented by the presence of several mechanisms of immune escape, which may represent a reason why immunotherapy clinical trials failed in this kind of tumor. In this review, we examine the current landscape of immunotherapy strategies in GBM, focusing on the challenge of immunoresistance and potential mechanisms to overcome it. We discussed completed and ongoing clinical trials involving immune checkpoint inhibitors, oncolytic viruses, vaccines, and CAR T-cell therapies, to provide insights into the efficacy and outcomes of different immunotherapeutic interventions. We also explore the impact of radiotherapy on the immune system within the GBM microenvironment highlighting the complex interactions between radiation treatment and the immune response.

Biomarkers of peripheral blood neutrophil extracellular traps in the diagnosis and progression of malignant tumors

BACKGROUND AND AIMS

The mortality rate associated with malignant tumors remains high and there is a lack of effective diagnostic and tumor progression markers. Neutrophil extracellular traps (NETs) can promote tumor-associated thrombosis, invasive metastasis, and inflammatory responses, but there is a lack of research on the value of measuring NETs in the peripheral blood of patients with malignancies.

METHODS

We included 263 patients with malignancies (55 gliomas, 101 ovarian, 64 colorectal, and 43 lung cancers) and 75 healthy controls in this study. We compared the levels of citrullinated histone H3 (citH3), cell-free DNA (cfDNA), and systemic inflammation-related parameters, including neutrophils, lymphocytes, monocytes, platelets, neutrophil-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, platelet-to-lymphocyte ratio, systemic immune inflammation index, and systemic inflammation response index. We assessed the value of changes in NETs in peripheral blood to determine the diagnosis, venous thromboembolism, clinical staging, and systemic inflammatory response in patients with malignancy.

RESULTS

The levels of citH3 and cfDNA in peripheral blood can distinguish between healthy controls and tumor patients. The levels of citH3 and cfDNA before clinical intervention did not predict the risk of combined venous thromboembolism in oncology patients in the short-term after clinical intervention. The levels of citH3, cfDNA, and systemic inflammation-related parameters in the peripheral blood of tumor patients increased with the clinical stage. There was a correlation between cfDNA levels in peripheral blood and systemic inflammation-related parameters in tumor patients, and this correlation was more significant in patients with advanced tumors.

CONCLUSIONS

Changes in NETs in the peripheral blood differ between healthy controls and patients with malignant tumors. NETs may be involved in tumor-induced systemic inflammatory responses through interaction with circulating inflammatory cells, thus promoting tumor progression. NETs may be used as markers to assist in the diagnosis and progression of tumor malignancy.

Novel orally bioavailable piperidine derivatives as extracellular arginase inhibitors developed by a ring expansion

Arginase is a multifaced enzyme that plays an important role in health and disease being regarded as a therapeutic target for the treatment of various pathological states such as malignancies, asthma, and cardiovascular disease. The discovery of boronic acid-based arginase inhibitors in 1997 revolutionized attempts of medicinal chemistry focused on development of drugs targeting arginase. Unfortunately, these very polar compounds had limitations such as analysis and purification without chromophores, synthetically challenging space, and poor oral bioavailability. Herein, we present a novel class of boronic acid-based arginase inhibitors which are piperidine derivatives exhibiting a different pharmacological profile compared to our drug candidate in cancer immunotherapy -OATD-02 - dual ARG1/2 inhibitor with high intracellular activity. Compounds from this new series show low intracellular activity, hence they can inhibit mainly extracellular arginase, providing different therapeutic space compared to a dual intracellular ARG1/2 inhibitor. The disclosed series showed good inhibitory potential towards arginase enzyme in vitro (IC50 up to 160 nM), favorable pharmacokinetics in animal models, and encouraging preliminary in vitro and in vivo tolerability. Compounds from the new series have moderate-to-high oral bioavailability (up to 66 %) and moderate clearance in vivo. Herein we describe the development and optimization of the synthesis of the new class of boronic acid-based arginase inhibitors via a ring expansion approach starting from the inexpensive chirality source (d-hydroxyproline). This upgraded methodology facilitated a gram-scale delivery of the final compound and eliminated the need for costly and time-consuming chiral resolution.

A closer look at the role of iron in glioblastoma

Glioblastoma (GBM) is among the deadliest malignancies facing modern oncology. While our understanding of certain aspects of GBM biology has significantly increased over the last decade, other aspects, such as the role of bioactive metals in GBM progression, remain understudied. Iron is the most abundant transition metal found within the earth's crust and plays an intricate role in human physiology owing to its ability to participate in oxidation-reduction reactions. The importance of iron homeostasis in human physiology is apparent when examining the clinical consequences of iron deficiency or iron overload. Despite this, the role of iron in GBM progression has not been well described. Here, we review and synthesize the existing literature examining iron's role in GBM progression and patient outcomes, as well as provide a survey of iron's effects on the major cell types found within the GBM microenvironment at the molecular and cellular level. Iron represents an accessible target given the availability of already approved iron supplements and chelators. Improving our understanding of iron's role in GBM biology may pave the way for iron-modulating approaches to improve patient outcomes.

Tumor-intrinsic metabolic reprogramming and how it drives resistance to anti-PD-1/PD-L1 treatment

The development of immune checkpoint blockade (ICB) therapies has been instrumental in advancing the field of immunotherapy. Despite the prominence of these treatments, many patients exhibit primary or acquired resistance, rendering them ineffective. For example, anti-programmed cell death protein 1 (anti-PD-1)/anti-programmed cell death ligand 1 (anti-PD-L1) treatments are widely utilized across a range of cancer indications, but the response rate is only 10%-30%. As such, it is necessary for researchers to identify targets and develop drugs that can be used in combination with existing ICB therapies to overcome resistance. The intersection of cancer, metabolism, and the immune system has gained considerable traction in recent years as a way to comprehensively study the mechanisms that drive oncogenesis, immune evasion, and immunotherapy resistance. As a result, new research is continuously emerging in support of targeting metabolic pathways as an adjuvant to ICB to boost patient response and overcome resistance. Due to the plethora of studies in recent years highlighting this notion, this review will integrate the relevant articles that demonstrate how tumor-derived alterations in energy, amino acid, and lipid metabolism dysregulate anti-tumor immune responses and drive resistance to anti-PD-1/PD-L1 therapy.

Siglec15 is a prognostic indicator and a potential tumor-related macrophage regulator that is involved in the suppressive immunomicroenvironment in gliomas

Background

Siglec15 is rising as a promising immunotherapeutic target in bladder, breast, gastric, and pancreatic cancers. The aim of the present study is to explore the prognostic value and immunotherapeutic possibilities of Siglec15 in gliomas using bioinformatics and clinicopathological methods.

Methods

The bioinformatics approach was used to examine Siglec15 mRNA expression in gliomas based on TCGA, CGGA, and GEO datasets. Then, the predictive value of Siglec15 expression on progression-free survival time (PFST) and overall survival time (OST) in glioma patients was comprehensively described.The TCGA database was screened for differentially expressed genes (DEGs) between the high and low Siglec15 expression groups, and enrichment analysis of the DEGs was performed. The Siglec15 protein expression and its prognostic impact in 92 glioma samples were explored using immunohistochemistry Next, the relationships between Siglec15 expression and infiltrating immune cells, immune regulators and multiple immune checkpoints were analysed.

Results

Bioinformatics analyses showed that high Siglec15 levels predicted poor clinical prognosis and adverse recurrence time in glioma patients. In the immunohistochemical study serving as a validation set, Siglec15 protein overexpression was found in 33.3% (10/30) of WHO grade II, 56% (14/25) of WHO grade III, and 70.3% (26/37) of WHO grade IV gliomas respectively. Siglec15 protein overexpression was also found to be an independent prognostic indicator detrimental to the PFST and OST of glioma patients. Enrichment analysis showed that the DEGs were mainly involved in pathways associated with immune function, including leukocyte transendothelial migration, focal adhesion, ECM receptor interaction, and T-cell receptor signaling pathways. In addition, high Siglec15 expression was related to M2 tumor-associated macrophages (TAMs), N2 tumor-infiltrating neutrophils, suppressive tumor immune microenvironment, and multiple immune checkpoint molecules. Immunofluorescence analysis confirmed the colocalization of Siglec15 and CD163 on TAMs.

Conclusion

Siglec15 overexpression is common in gliomas and predicts an adverse recurrence time and overall survival time. Siglec15 is a potential target for immunotherapy and a potential TAMs regulator that is involved in the suppressed immunomicroenvironment in gliomas.

LPCAT1 enhances the invasion and migration in gastric cancer: Based on computational biology methods and in vitro experiments

BACKGROUND AND AIM

The biological functions and clinical implications of lysophosphatidylcholine acyltransferase 1 (LPCAT1) remain unclarified in gastric cancer (GC). The aim of the current study was to explore the possible clinicopathological significance of LPCAT1 and its perspective mechanism in GC tissues.

MATERIALS AND METHODS

The protein expression and mRNA levels of LPCAT1 were detected from in-house immunohistochemistry and public high-throughput RNA arrays and RNA sequencing. To have a comprehensive understanding of the clinical value of LPCAT1 in GC, all enrolled data were integrated to calculate the expression difference and standard mean difference (SMD). The biological mechanism of LPCAT1 in GC was confirmed by computational biology and in vitro experiments. Migration and invasion assays were also conducted to confirm the effect of LPCAT1 in GC.

RESULTS

Both protein and mRNA expression levels of LPCAT1 in GC were remarkably higher than those in noncancerous controls. Comprehensively, the SMD of LPCAT1 mRNA was 1.11 (95% CI = 0.86-1.36) in GC, and the summarized AUC was 0.85 based on 15 datasets containing 1727 cases of GC and 940 cases of non-GC controls. Moreover, LPCAT1 could accelerate the invasion and migration of GC by boosting the neutrophil degranulation pathway and disturbing the immune microenvironment.

CONCLUSION

An increased level of LPCAT1 may promote the progression of GC.

Local and systemic effects of IDH mutations on primary glioma patients

Adult gliomas are divided into isocitrate dehydrogenase (IDH) wild-type and IDH mutant subtypes according to the new 2021 World Health Organization classification system. However, the local and systemic effects of IDH mutations on primary glioma patients are not well illustrated. Retrospective analysis, immune-cell infiltration analysis, meta-analysis, and immunohistochemistry assay were applied in the present study. The results from our cohort showed that IDH mutant gliomas own a lower proliferating rate compared to that in wild-type gliomas. Patients with mutant IDH exhibited a higher frequency of seizures in both our cohort and the cohort from the meta-analysis. Mutations in IDH result in lower levels of intra-tumour but higher levels of circulating CD4+ and CD8+ T lymphocytes. Levels of neutrophils in both intra-tumour and circulating blood were lower in IDH mutant gliomas. Moreover, IDH mutant glioma patients receiving radiotherapy in combination with chemotherapy exhibited better overall survival with respect to radiotherapy alone. Mutations in IDH alters the local and circulating immune microenvironment, and increases the sensitivity of tumour cell to chemotherapy.

Monocyte depletion enhances neutrophil influx and proneural to mesenchymal transition in glioblastoma

Myeloid cells comprise the majority of immune cells in tumors, contributing to tumor growth and therapeutic resistance. Incomplete understanding of myeloid cells response to tumor driver mutation and therapeutic intervention impedes effective therapeutic design. Here, by leveraging CRISPR/Cas9-based genome editing, we generate a mouse model that is deficient of all monocyte chemoattractant proteins. Using this strain, we effectively abolish monocyte infiltration in genetically engineered murine models of de novo glioblastoma (GBM) and hepatocellular carcinoma (HCC), which show differential enrichment patterns for monocytes and neutrophils. Eliminating monocyte chemoattraction in monocyte enriched PDGFB-driven GBM invokes a compensatory neutrophil influx, while having no effect on Nf1-silenced GBM model. Single-cell RNA sequencing reveals that intratumoral neutrophils promote proneural-to-mesenchymal transition and increase hypoxia in PDGFB-driven GBM. We further demonstrate neutrophil-derived TNF-a directly drives mesenchymal transition in PDGFB-driven primary GBM cells. Genetic or pharmacological inhibiting neutrophils in HCC or monocyte-deficient PDGFB-driven and Nf1-silenced GBM models extend the survival of tumor-bearing mice. Our findings demonstrate tumor-type and genotype dependent infiltration and function of monocytes and neutrophils and highlight the importance of targeting them simultaneously for cancer treatments.

Radiation-induced circulating myeloid-derived suppressor cells induce systemic lymphopenia after chemoradiotherapy in patients with glioblastoma

Severe and prolonged lymphopenia frequently occurs in patients with glioblastoma after standard chemoradiotherapy and has been associated with worse survival, but its underlying biological mechanism is not well understood. To address this, we performed a correlative study in which we collected and analyzed peripheral blood of patients with glioblastoma (n = 20) receiving chemoradiotherapy using genomic and immune monitoring technologies. RNA sequencing analysis of the peripheral blood mononuclear cells (PBMC) showed an elevated concentration of myeloid-derived suppressor cell (MDSC) regulatory genes in patients with lymphopenia when compared with patients without lymphopenia after chemoradiotherapy. Additional analysis including flow cytometry and single-cell RNA sequencing further confirmed increased numbers of circulating MDSC in patients with lymphopenia when compared with patients without lymphopenia after chemoradiotherapy. Preclinical murine models were also established and demonstrated a causal relationship between radiation-induced MDSC and systemic lymphopenia using transfusion and depletion experiments. Pharmacological inhibition of MDSC using an arginase-1 inhibitor (CB1158) or phosphodiesterase-5 inhibitor (tadalafil) during radiation therapy (RT) successfully abrogated radiation-induced lymphopenia and improved survival in the preclinical models. CB1158 and tadalafil are promising drugs in reducing radiation-induced lymphopenia in patients with glioblastoma. These results demonstrate the promise of using these classes of drugs to reduce treatment-related lymphopenia and immunosuppression.

Antibody Profiling and In Silico Functional Analysis of Differentially Reactive Antibody Signatures of Glioblastomas and Meningiomas

Studies on tumor-associated antigens in brain tumors are sparse. There is scope for enhancing our understanding of molecular pathology, in order to improve on existing forms, and discover new forms, of treatment, which could be particularly relevant to immuno-oncological strategies. To elucidate immunological differences, and to provide another level of biological information, we performed antibody profiling, based on a high-density protein array (containing 8173 human transcripts), using IgG isolated from the sera of n = 12 preoperative and n = 16 postoperative glioblastomas, n = 26 preoperative and n = 29 postoperative meningiomas, and n = 27 healthy, cancer-free controls. Differentially reactive antigens were compared to gene expression data from an alternate public GBM data set from OncoDB, and were analyzed using the Reactome pathway browser. Protein array analysis identified approximately 350-800 differentially reactive antigens, and revealed different antigen profiles in the glioblastomas and meningiomas, with approximately 20-30%-similar and 10-15%-similar antigens in preoperative and postoperative sera, respectively. Seroreactivity did not correlate with OncoDB-derived gene expression. Antigens in the preoperative glioblastoma sera were enriched for signaling pathways, such as signaling by Rho-GTPases, COPI-mediated anterograde transport and vesicle-mediated transport, while the infectious disease, SRP-dependent membrane targeting cotranslational proteins were enriched in the meningiomas. The pre-vs. postoperative seroreactivity in the glioblastomas was enriched for antigens, e.g., platelet degranulation and metabolism of lipid pathways; in the meningiomas, the antigens were enriched in infectious diseases, metabolism of amino acids and derivatives, and cell cycle. Antibody profiling in both tumor entities elucidated several hundred antigens and characteristic signaling pathways that may provide new insights into molecular pathology and may be of interest for the development of new treatment strategies.

Inflammation in Urological Malignancies: The Silent Killer

Several studies have investigated the role of inflammation in promoting tumorigenesis and cancer progression. Neoplastic as well as surrounding stromal and inflammatory cells engage in well-orchestrated reciprocal interactions to establish an inflammatory tumor microenvironment. The tumor-associated inflammatory tissue is highly plastic, capable of continuously modifying its phenotypic and functional characteristics. Accumulating evidence suggests that chronic inflammation plays a critical role in the development of urological cancers. Here, we review the origins of inflammation in urothelial, prostatic, renal, testicular, and penile cancers, focusing on the mechanisms that drive tumor initiation, growth, progression, and metastasis. We also discuss how tumor-associated inflammatory tissue may be a diagnostic marker of clinically significant tumor progression risk and the target for future anti-cancer therapies.

N1 versus N2 and PMN-MDSC: A critical appraisal of current concepts on tumor-associated neutrophils and new directions for human oncology

Research on tumor-associated neutrophils (TAN) currently surges because of the well-documented strong clinical relevance of tumor-infiltrating neutrophils. This relevance is illustrated by strong correlations between high frequencies of intratumoral neutrophils and poor outcome in the majority of human cancers. Recent high-dimensional analysis of murine neutrophils provides evidence for unexpected plasticity of neutrophils in murine models of cancer and other inflammatory non-malignant diseases. New analysis tools enable deeper insight into the process of neutrophil differentiation and maturation. These technological and scientific developments led to the description of an ever-increasing number of distinct transcriptional states and associated phenotypes in murine models of disease and more recently also in humans. At present, functional validation of these different transcriptional states and potential phenotypes in cancer is lacking. Current functional concepts on neutrophils in cancer rely mainly on the myeloid-derived suppressor cell (MDSC) concept and the dichotomous and simple N1-N2 paradigm. In this manuscript, we review the historic development of those concepts, critically evaluate these concepts against the background of our own work and provide suggestions for a refinement of current concepts in order to facilitate the transition of TAN research from experimental insight to clinical translation.

Pediatric versus adult high grade glioma: Immunotherapeutic and genomic considerations

High grade gliomas are identified as malignant central nervous tumors that spread rapidly and have a universally poor prognosis. Historically high grade gliomas in the pediatric population have been treated similarly to adult high grade gliomas. For the first time, the most recent classification of central nervous system tumors by World Health Organization has divided adult from pediatric type diffuse high grade gliomas, underscoring the biologic differences between these tumors in different age groups. The objective of our review is to compare high grade gliomas in the adult versus pediatric patient populations, highlighting similarities and differences in epidemiology, etiology, pathogenesis and therapeutic approaches. High grade gliomas in adults versus children have varying clinical presentations, molecular biology background, and response to chemotherapy, as well as unique molecular targets. However, increasing evidence show that they both respond to recently developed immunotherapies. This review summarizes the distinctions and commonalities between the two in disease pathogenesis and response to therapeutic interventions with a focus on immunotherapy.

Development of a Novel Prognostic Model of Glioblastoma Based on m6A-Associated Immune Genes and Identification of a New Biomarker

Background

Accumulating evidence shows that m6A regulates oncogene and tumor suppressor gene expression, thus playing a dual role in cancer. Likewise, there is a close relationship between the immune system and tumor development and progression. However, for glioblastoma, m6A-associated immunological markers remain to be identified.

Methods

We obtained gene expression, mutation, and clinical data on glioblastoma from The Cancer Genome Atlas and Chinese Glioma Genome Atlas databases. Next, we performed univariate COX–least absolute shrinkage and selection operator (LASSO)–multivariate COX regression analyses to establish a prognostic gene signature and develop a corresponding dynamic nomogram application. We then carried out a clustering analysis twice to categorize all samples according to their m6A-regulating and m6A-associated immune gene expression levels (high, medium, and low) and calculated their m6A score. Finally, we performed quantitative reverse transcription-polymerase chain reaction, cell counting kit-8, cell stemness detection, cell migration, and apoptosis detection in vitro assays to determine the biological role of CD81 in glioblastoma cells.

Results

Our glioblastoma risk score model had extremely high prediction efficacy, with the area under the receiver operating characteristic curve reaching 0.9. The web version of the dynamic nomogram application allows rapid and accurate calculation of patients’ survival odds. Survival curves and Sankey diagrams indicated that the high-m6A score group corresponded to the groups expressing medium and low m6A-regulating gene levels and high m6A-associated prognostic immune gene levels. Moreover, these groups displayed lower survival rates and higher immune infiltration. Based on the gene set enrichment analysis, the pathophysiological mechanism may be related to the activation of the immunosuppressive function and related signaling pathways. Moreover, the risk score model allowed us to perform immunotherapy benefit assessment. Finally, silencing CD81 in vitro significantly suppressed proliferation, stemness, and migration and facilitated apoptosis in glioblastoma cells.

Conclusion

We developed an accurate and efficient prognostic model. Furthermore, the correlation analysis of different stratification methods with tumor microenvironment provided a basis for further pathophysiological mechanism exploration. Finally, CD81 may serve as a diagnostic and prognostic biomarker in glioblastoma.

Neutrophils: New Critical Regulators of Glioma

In cancer, neutrophils are an important part of the tumour microenvironment (TME). Previous studies have shown that circulating and infiltrating neutrophils are associated with malignant progression and immunosuppression in gliomas. However, recent studies have shown that neutrophils have an antitumour effect. In this review, we focus on the functional roles of neutrophils in the circulation and tumour sites in patients with glioma. The mechanisms of neutrophil recruitment, immunosuppression and the differentiation of neutrophils are discussed. Finally, the potential of neutrophils as clinical biomarkers and therapeutic targets is highlighted. This review can help us gain a deeper and systematic understanding of the role of neutrophils, and provide new insights for treatment in gliomas.

Overcoming resistance to αPD-1 of MMR-deficient tumors with high tumor-induced neutrophils levels by combination of αCTLA-4 and αPD-1 blockers

BACKGROUND

Clinical studies have highlighted the efficacy of anti-programmed death 1 (αPD-1) monoclonal antibodies in patients with DNA mismatch repair-deficient (MMRD) tumors. However, the responsiveness of MMRD cancers to αPD-1 therapy is highly heterogeneous, and the origins of this variability remain not fully understood.

METHODS

4T1 and CT26 mouse tumor cell lines were inactivated for the MMRD gene Msh2, leading to a massive accumulation of mutations after serial passages of cells. Insertions/deletion events and mutation load were evaluated by whole exome sequencing. Mice bearing highly mutated MMRD tumor or parental tumors were treated with αPD-1 and tumor volume was monitored. Immune cell type abundance was dynamically assessed in the tumor microenvironment and the blood by flow cytometry. Neutrophils were depleted in mice using αLY6G antibody, and regulatory T (Treg) cell population was reduced with αCD25 or anti-cytotoxic T-lymphocytes-associated protein 4 (αCTLA-4) antibodies. Patients with MMRD tumors treated with immune checkpoint blockade-based therapy were retrospectively identified and neutrophil-to-lymphocyte ratio (NLR) was evaluated and examined for correlation with clinical benefit.

RESULTS

By recapitulating mismatch repair deficiency in different mouse tumor models, we revealed that elevated circulating tumor-induced neutrophils (TIN) in hypermutated MMRD tumors hampered response to αPD-1 monotherapy. Importantly, depletion of TIN using αLy-6G antibody reduced Treg cells and restored αPD-1 response. Conversely, targeting Treg cells by αCD25 or αCTLA-4 antibodies limited peripheral TIN accumulation and elicited response in αPD-1-resistant MMRD tumors, highlighting a crosstalk between TIN and Treg cells. Thus, αPD-1+αCTLA-4 combination overcomes TIN-induced resistance to αPD-1 in mice bearing MMRD tumors. Finally, in a cohort of human (high microsatellite instability)/MMRD tumors we revealed that early on-treatment change in the NLR ratio may predict resistance to αPD-1 therapy.

CONCLUSIONS

TIN countered αPD-1 efficacy in MMRD tumors. Since αCTLA-4 could restrict TIN accumulation, αPD-1+αCTLA-4 combination overcomes αPD-1 resistance in hosts with hypermutated MMRD tumors displaying abnormal neutrophil accumulation.

Old and New Systemic Immune-Inflammation Indexes Are Associated with Overall Survival of Glioblastoma Patients Treated with Radio-Chemotherapy

Background. Systemic immunity and inflammation indexes (SI) derived from blood cells have gained increasing attention in clinical oncology as potential biomarkers that are associated with survival. Materials and methods. We tested 12 different SI using blood tests from patients with isocitrate dehydrogenase 1 and 2 wild-type glioblastomas, treated with radio-chemotherapy. The primary endpoint was their overall survival. Results. A total of 77 patients, comprising 43 males and 34 females, with a median age of 64 years (age range 26-84), who were treated between October 2010 and July 2020, were included in the present analysis (approved by a local ethics committee). In the univariate Cox regression analysis, all the indexes except two showed a statistically significant impact on OS. In the multivariate Cox regression analysis, neutrophil × platelet × leukocyte/(lymphocyte × monocyte) (NPW/LM) and neutrophil × platelet × monocyte/lymphocyte (NPM/L) maintained their statistically significant impact value. Conclusions. This univariate analysis confirms the potential of systemic inflammation indexes in patients with glioblastoma, while the multivariate analysis verifies the prognostic value of NPW/LM and NPM/L.

Arginase: An emerging and promising therapeutic target for cancer treatment

Arginase is a key hydrolase in the urea cycle that hydrolyses L-arginine to urea and L-ornithine. Increasing number of studies in recent years demonstrate that two mammalian arginase isoforms, arginase 1 (ARG1) and arginase 2 (ARG2), were aberrantly upregulated in various types of cancers, and played crucial roles in the regulation of tumor growth and metastasis through various mechanisms such as regulating L-arginine metabolism, influencing tumor immune microenvironment, etc. Thus, arginase receives increasing focus as an attractive target for cancer therapy. In this review, we provide a comprehensive overview of the physiological and biological roles of arginase in a variety of cancers, and shed light on the underlying mechanisms of arginase mediating cancer cells growth and development, as well as summarize the recent clinical research advances of targeting arginase for cancer therapy.

Mechanistic insights into the interplays between neutrophils and other immune cells in cancer development and progression

Cancer is considered a major public health concern worldwide and is characterized by an uncontrolled division of abnormal cells. The human immune system recognizes cancerous cells and induces innate immunity to destroy those cells. However, sustained tumors may protect themselves by developing immune escape mechanisms through multiple soluble and cellular mediators. Neutrophils are the most plenteous leukocytes in the human blood and are crucial for immune defense in infection and inflammation. Besides, neutrophils emancipate the antimicrobial contents, secrete different cytokines or chemokines, and interact with other immune cells to combat and successfully kill cancerous cells. Conversely, many clinical and experimental studies signpost that being a polarized and heterogeneous population with plasticity, neutrophils, particularly their subpopulations, act as a modulator of cancer development by promoting tumor metastasis, angiogenesis, and immunosuppression. Studies also suggest that tumor infiltrating macrophages, neutrophils, and other innate immune cells support tumor growth and survival. Additionally, neutrophils promote tumor cell invasion, migration and intravasation, epithelial to mesenchymal transition, survival of cancer cells in the circulation, seeding, and extravasation of tumor cells, and advanced growth and development of cancer cells to form metastases. In this manuscript, we describe and review recent studies on the mechanisms for neutrophil recruitment, activation, and their interplay with different immune cells to promote their pro-tumorigenic functions. Understanding the detailed mechanisms of neutrophil-tumor cell interactions and the concomitant roles of other immune cells will substantially improve the clinical utility of neutrophils in cancer and eventually may aid in the identification of biomarkers for cancer prognosis and the development of novel therapeutic approaches for cancer treatment.

Ferroptosis-Related Gene Contributes to Immunity, Stemness and Predicts Prognosis in Glioblastoma Multiforme

Ferroptosis, a recently discovered regulated programmed cell death, is associated with tumorigenesis and progression in glioblastoma. Based on widely recognized ferroptosis-related genes (FRGs), the regulation of ferroptosis patterns and corresponding characteristics of immune infiltration of 516 GBM samples with GSE13041, TCGA-GBM, and CGGA-325 were comprehensively analyzed. Here, we revealed the expression, mutations, and CNV of FRGs in GBM. We identified three distinct regulation patterns of ferroptosis and found the hub genes of immunity and stemness among DEGs in three patterns. A prognostic model was constructed based on five FRGs and verified at the mRNA and protein level. The risk score can not only predict the prognosis but also the degree of immune infiltration and ICB responsiveness by functional annotation. The overall assessment of FRGs in GBM patients will guide the direction of improved research and develop new prognostic prediction tools.

Myeloid Diagnostic and Prognostic Markers of Immune Suppression in the Blood of Glioma Patients

Background

Although gliomas are confined to the central nervous system, their negative influence over the immune system extends to peripheral circulation. The immune suppression exerted by myeloid cells can affect both response to therapy and disease outcome. We analyzed the expansion of several myeloid parameters in the blood of low- and high-grade gliomas and assessed their relevance as biomarkers of disease and clinical outcome.

Methods

Peripheral blood was obtained from 134 low- and high-grade glioma patients. CD14⁺, CD14⁺/p-STAT3⁺, CD14⁺/PD-L1⁺, CD15⁺ cells and four myeloid-derived suppressor cell (MDSC) subsets, were evaluated by flow cytometry. Arginase-1 (ARG1) quantity and activity was determined in the plasma. Multivariable logistic regression model was used to obtain a diagnostic score to discriminate glioma patients from healthy controls and between each glioma grade. A glioblastoma prognostic model was determined by multiple Cox regression using clinical and myeloid parameters.

Results

Changes in myeloid parameters associated with immune suppression allowed to define a diagnostic score calculating the risk of being a glioma patient. The same parameters, together with age, permit to calculate the risk score in differentiating each glioma grade. A prognostic model for glioblastoma patients stemmed out from a Cox multiple analysis, highlighting the role of MDSC, p-STAT3, and ARG1 activity together with clinical parameters in predicting patient’s outcome.

Conclusions

This work emphasizes the role of systemic immune suppression carried out by myeloid cells in gliomas. The identification of biomarkers associated with immune landscape, diagnosis, and outcome of glioblastoma patients lays the ground for their clinical use.

Friends with Benefits: Chemokines, Glioblastoma-Associated Microglia/Macrophages, and Tumor Microenvironment

Glioma is the most common primary intracranial tumor and has the greatest prevalence of all brain tumors. Treatment resistance and tumor recurrence in GBM are mostly explained by considerable alterations within the tumor microenvironment, as well as extraordinary cellular and molecular heterogeneity. Soluble factors, extracellular matrix components, tissue-resident cell types, resident or newly recruited immune cells together make up the GBM microenvironment. Regardless of many immune cells, a profound state of tumor immunosuppression is supported and developed, posing a considerable hurdle to cancer cells' immune-mediated destruction. Several studies have suggested that various GBM subtypes present different modifications in their microenvironment, although the importance of the microenvironment in treatment response has yet to be determined. Understanding the microenvironment and how it changes after therapies is critical because it can influence the remaining invasive GSCs and lead to recurrence. This review article sheds light on the various components of the GBM microenvironment and their roles in tumoral development, as well as immune-related biological processes that support the interconnection/interrelationship between different cell types. Also, we summarize the current understanding of the modulation of soluble factors and highlight the dysregulated inflammatory chemokine/specific receptors cascades/networks and their significance in tumorigenesis, cancer-related inflammation, and metastasis.

Polymorphonuclear Neutrophils and Tumors: Friend or Foe?

Tumor microenvironment (TME) is a dynamic network that apart from tumor cells includes also cells of the immune system, e.g., neutrophils, which are recruited from blood circulation. In TME, neutrophils are strongly implicated in the direct and indirect interactions with tumor cells or other immune cells, and they play roles in both preventing and/or facilitating tumor progression and metastasis. The dual role of neutrophils is determined by their high plasticity and heterogeneity. Analogous to the macrophages, neutrophils can express antitumoral (N1) and protumoral (N2) phenotypes which differ substantially in morphology and function. N1 phenotype characterizes with a high cytotoxic and proinflammatory activities, while N2 phenotype with immunosuppressive and prometastatic properties. The antitumoral effect of neutrophils includes for example the production of reactive oxygen species or proapoptotic molecules. The protumoral action of neutrophils relies on releasing of proangiogenic and prometastatic mediators, immunosuppressive factors, as well as on direct helping tumor cells in extravasation process. This chapter summarizes the heterogeneity of neutrophils in TME, as well as their dual role on tumor cells.

The multifaceted mechanisms of malignant glioblastoma progression and clinical implications

With the application of high throughput sequencing technologies at single-cell resolution, studies of the tumor microenvironment in glioblastoma, one of the most aggressive and invasive of all cancers, have revealed immense cellular and tissue heterogeneity. A unique extracellular scaffold system adapts to and supports progressive infiltration and migration of tumor cells, which is characterized by altered composition, effector delivery, and mechanical properties. The spatiotemporal interactions between malignant and immune cells generate an immunosuppressive microenvironment, contributing to the failure of effective anti-tumor immune attack. Among the heterogeneous tumor cell subpopulations of glioblastoma, glioma stem cells (GSCs), which exhibit tumorigenic properties and strong invasive capacity, are critical for tumor growth and are believed to contribute to therapeutic resistance and tumor recurrence. Here we discuss the role of extracellular matrix and immune cell populations, major components of the tumor ecosystem in glioblastoma, as well as signaling pathways that regulate GSC maintenance and invasion. We also highlight emerging advances in therapeutic targeting of these components.

Macrophage and Neutrophil Interactions in the Pancreatic Tumor Microenvironment Drive the Pathogenesis of Pancreatic Cancer

Simple Summary

The survival rates for patients with pancreatic adenocarcinoma are very low. This dismal prognosis is due in part to late detection and early development of metastases, and successful treatments for pancreatic adenocarcinoma are also lacking. One potential method of treatment is immunotherapy, which has been successfully implemented in several cancers. Despite success in other cancer types, there has been little progress in pancreatic adenocarcinoma. To understand these shortcomings, we explore the roles of macrophages and neutrophils, two prominent immune cell types in the pancreatic tumor environment. In this review, we discuss how macrophages and neutrophils lead to the harsh environment that is unique to pancreatic adenocarcinoma. We further explore how these immune cells can impact standard of care therapies and decrease their effectiveness. Macrophages and neutrophils could ultimately be targeted to improve outcomes for patients with pancreatic adenocarcinoma.

Abstract

Despite modest improvements in survival in recent years, pancreatic adenocarcinoma remains a deadly disease with a 5-year survival rate of only 9%. These poor outcomes are driven by failure of early detection, treatment resistance, and propensity for early metastatic spread. Uncovering innovative therapeutic modalities to target the resistance mechanisms that make pancreatic cancer largely incurable are urgently needed. In this review, we discuss the immune composition of pancreatic tumors, including the counterintuitive fact that there is a significant inflammatory immune infiltrate in pancreatic cancer yet anti-tumor mechanisms are subverted and immune behaviors are suppressed. Here, we emphasize how immune cell interactions generate tumor progression and treatment resistance. We narrow in on tumor macrophage (TAM) spatial arrangement, polarity/function, recruitment, and origin to introduce a concept where interactions with tumor neutrophils (TAN) perpetuate the microenvironment. The sequelae of macrophage and neutrophil activities contributes to tumor remodeling, fibrosis, hypoxia, and progression. We also discuss immune mechanisms driving resistance to standard of care modalities. Finally, we describe a cadre of treatment targets, including those intended to overcome TAM and TAN recruitment and function, to circumvent barriers presented by immune infiltration in pancreatic adenocarcinoma.

Correlation of AIF-1 Expression with Immune and Clinical Features in 1270 Glioma Samples

AIF-1 gene is surrounded by the genes involved in the inflammatory response and located in the major histocompatibility complex (MHC) class III genomic region. It has been found that microglial cells expressed the AIF-1 gene during all stages of mice brain development. However, the role of AIF-1 remains unclear in glioma. A total of 1270 glioma patients from three independent data sets were enrolled in the study. TIMER platform was used for comprehensive molecular characterization of tumor immune infiltrates. Sangerbox was used to analyze AIF-1 RNA sequencing expression data of tumors and normal samples, and to evaluate the association between AIF-1 expression and 29 sub-populations of immune cells. The R language 3.63 was used to identify differentially expressed genes for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Kaplan-Meier survival analysis and univariate/multivariate Cox analysis were used to examine survival distributions. We found that AIF-1 gene was prominently up-regulated, especially in brain glioma including LGG and GBM. A strong correlation was observed between AIF-1 expression and the majority of immune cells, particularly in macrophage, myeloid-derived suppressor cells. Moreover, AIF-1 expression was correlated with immune infiltration level. We found that AIF-1 expression was strongly correlated with the specific immune and prognostic cell markers of monocytes, microglia and macrophages, M1 macrophages, and M2 macrophages after normalization through tumor purity in TCGA-LGG and TCGA-GBM. Higher expression level of AIF-1 was found to be significantly correlated with poor prognosis. GO analysis and KEGG pathways indicated that AIF-1 could affect glioma-related immune activities. Our study suggests that AIF-1 can be treated as a prognostic biomarker for glioma patients. AIF-1 was involved in pro-tumor processes and the regulation of immune status and correlates with poor prognosis.

The Eclectic Nature of Glioma-Infiltrating Macrophages and Microglia

Glioblastomas (GBMs) are complex ecosystems composed of highly multifaceted tumor and myeloid cells capable of responding to different environmental pressures, including therapies. Recent studies have uncovered the diverse phenotypical identities of brain-populating myeloid cells. Differences in the immune proportions and phenotypes within tumors seem to be dictated by molecular features of glioma cells. Furthermore, increasing evidence underscores the significance of interactions between myeloid cells and glioma cells that allow them to evolve in a synergistic fashion to sustain tumor growth. In this review, we revisit the current understanding of glioma-infiltrating myeloid cells and their dialogue with tumor cells in consideration of their increasing recognition in response and resistance to immunotherapies as well as the immune impact of the current chemoradiotherapy used to treat gliomas.

A Simple Preoperative Blood Count to Stratify Prognosis in Isocitrate Dehydrogenase-Wildtype Glioblastoma Patients Treated with Radiotherapy plus Concomitant and Adjuvant Temozolomide

PURPOSE

The survival times of glioblastoma (GB) patients after the standard therapy including safe maximal resection followed by radiotherapy plus concomitant and adjuvant temozolomide are heterogeneous. In order to define a simple, reliable method for predicting whether patients with isocitrate dehydrogenase (IDH)-wildtype GB treated with the standard therapy will be short- or long-term survivors, we analyzed the correlation of preoperative blood counts and their combined forms with progression-free survival (PFS) and overall survival (OS) in these patients.

METHODS

Eighty-five patients with primary IDH-wildtype GB treated with the standard therapy between 2012 and 2019 were analyzed retrospectively. Cox proportional hazards models and Kaplan-Meier analysis were used to investigate the survival function of preoperative hematological parameters.

RESULTS

Preoperative high neutrophil-to-lymphocyte ratio (NLR, >2.42), high platelet count (>236 × 10⁹/L), and low red blood cell (RBC) count (≤4.59 × 10¹²/L) were independent prognostic factors for poorer OS (p = 0.030, p = 0.030, and p = 0.004, respectively). Moreover, a high NLR was an independent prognostic factor for shorter PFS (p = 0.010). We also found that, like NLR, preoperative high derived NLR (dNLR, >1.89) was of poor prognostic value for both PFS (p = 0.002) and OS (p = 0.033). A significant correlation was observed between NLR and dNLR (r = 0.88, p < 0.001), which had a similar prognostic power for OS (NLR: AUC = 0.58; 95% CI: [0.48; 0.68]; dNLR: AUC = 0.62; 95% CI: [0.51; 0.72]). Two scores, one based on preoperative platelet and RBC counts plus NLR and the other on preoperative platelet and RBC counts plus dNLR, were found to be independent prognostic factors for PFS (p = 0.006 and p = 0.002, respectively) and OS (p < 0.001 for both scores).

CONCLUSION

Cheap, routinely ordered, preoperative assessments of blood markers, such as NLR, dNLR, RBC, and platelet counts, can predict the survival outcomes of patients with IDH-wildtype GB treated with the standard therapy.

Immunosuppression in Glioblastoma: Current Understanding and Therapeutic Implications

Glioblastoma (GBM) is the most common primary brain tumor in adults an carries and carries a terrible prognosis. The current regiment of surgical resection, radiation, and chemotherapy has remained largely unchanged in recent years as new therapeutic approaches have struggled to demonstrate benefit. One of the most challenging hurdles to overcome in developing novel treatments is the profound immune suppression found in many GBM patients. This limits the utility of all manner of immunotherapeutic agents, which have revolutionized the treatment of a number of cancers in recent years, but have failed to show similar benefit in GBM therapy. Understanding the mechanisms of tumor-mediated immune suppression in GBM is critical to the development of effective novel therapies, and reversal of this effect may prove key to effective immunotherapy for GBM. In this review, we discuss the current understanding of tumor-mediated immune suppression in GBM in both the local tumor microenvironment and systemically. We also discuss the effects of current GBM therapy on the immune system. We specifically explore some of the downstream effectors of tumor-driven immune suppression, particularly myeloid-derived suppressor cells (MDSCs) and other immunosuppressive monocytes, and the manner by which GBM induces their formation, with particular attention to the role of GBM-derived extracellular vesicles (EVs). Lastly, we briefly review the current state of immunotherapy for GBM and discuss additional hurdles to overcome identification and implementation of effective therapeutic strategies.

Phenotypic plasticity of myeloid cells in glioblastoma development, progression, and therapeutics

Glioblastoma (GBM) is the most common and malignant type of intracranial tumors with poor prognosis. Accumulating evidence suggests that phenotypic alterations of infiltrating myeloid cells in the tumor microenvironment are important for GBM progression. Conventional tumor immunotherapy commonly targets T-cells, while innate immunity as a therapeutic target is an emerging field. Targeting infiltrating myeloid cells that induce immune suppression in the TME provides a novel direction to improve the prognosis of patients with GBM. The factors released by tumor cells recruit myeloid cells into tumor bed and reprogram infiltrating myeloid cells into immunostimulatory/immunosuppressive phenotypes. Reciprocally, infiltrating myeloid cells, especially microglia/macrophages, regulate GBM progression and affect therapeutic efficacy. Herein, we revisited biological characteristics and functions of infiltrating myeloid cells and discussed the recent advances in immunotherapies targeting infiltrating myeloid cells in GBM. With an evolving understanding of the complex interactions between infiltrating myeloid cells and tumor cells in the tumor microenvironment, we will expand novel immunotherapeutic regimens targeting infiltrating myeloid cells in GBM treatment and improve the outcomes of GBM patients.

Mild and Asymptomatic COVID-19 Convalescents Present Long-Term Endotype of Immunosuppression Associated With Neutrophil Subsets Possessing Regulatory Functions

The SARS-CoV-2 infection [coronavirus disease 2019 (COVID-19)] is associated with severe lymphopenia and impaired immune response, including expansion of myeloid cells with regulatory functions, e.g., so-called low-density neutrophils, containing granulocytic myeloid-derived suppressor cells (LDNs/PMN-MDSCs). These cells have been described in both infections and cancer and are known for their immunosuppressive activity. In the case of COVID-19, long-term complications have been frequently observed (long-COVID). In this context, we aimed to investigate the immune response of COVID-19 convalescents after a mild or asymptomatic course of disease. We enrolled 13 convalescents who underwent a mild or asymptomatic infection with SARS-CoV-2, confirmed by a positive result of the PCR test, and 13 healthy donors without SARS-CoV-2 infection in the past. Whole blood was used for T-cell subpopulation and LDNs/PMN-MDSCs analysis. LDNs/PMN-MDSCs and normal density neutrophils (NDNs) were sorted out by FACS and used for T-cell proliferation assay with autologous T cells activated with anti-CD3 mAb. Serum samples were used for the detection of anti-SARS-CoV-2 neutralizing IgG and GM-CSF concentration. Our results showed that in convalescents, even 3 months after infection, an elevated level of LDNs/PMN-MDSCs is still maintained in the blood, which correlates negatively with the level of CD8+ and double-negative T cells. Moreover, LDNs/PMN-MDSCs and NDNs showed a tendency for affecting the production of anti-SARS-CoV-2 S1 neutralizing antibodies. Surprisingly, our data showed that in addition to LDNs/PMN-MDSCs, NDNs from convalescents also inhibit proliferation of autologous T cells. Additionally, in the convalescent sera, we detected significantly higher concentrations of GM-CSF, indicating the role of emergency granulopoiesis. We conclude that in mild or asymptomatic COVID-19 convalescents, the neutrophil dysfunction, including propagation of PD-L1-positive LDNs/PMN-MDSCs and NDNs, is responsible for long-term endotype of immunosuppression.

Marine Power on Cancer: Drugs, Lead Compounds, and Mechanisms

Worldwide, 19.3 million new cancer cases and almost 10.0 million cancer deaths occur each year. Recently, much attention has been paid to the ocean, the largest biosphere of the earth that harbors a great many different organisms and natural products, to identify novel drugs and drug candidates to fight against malignant neoplasms. The marine compounds show potent anticancer activity in vitro and in vivo, and relatively few drugs have been approved by the U.S. Food and Drug Administration for the treatment of metastatic malignant lymphoma, breast cancer, or Hodgkin's disease. This review provides a summary of the anticancer effects and mechanisms of action of selected marine compounds, including cytarabine, eribulin, marizomib, plitidepsin, trabectedin, zalypsis, adcetris, and OKI-179. The future development of anticancer marine drugs requires innovative biochemical biology approaches and introduction of novel therapeutic targets, as well as efficient isolation and synthesis of marine-derived natural compounds and derivatives.

Role of Inflammatory Mediators, Macrophages, and Neutrophils in Glioma Maintenance and Progression: Mechanistic Understanding and Potential Therapeutic Applications

Gliomas are the most common, highly malignant, and deadliest forms of brain tumors. These intra-cranial solid tumors are comprised of both cancerous and non-cancerous cells, which contribute to tumor development, progression, and resistance to the therapeutic regimen. A variety of soluble inflammatory mediators (e.g., cytokines, chemokines, and chemotactic factors) are secreted by these cells, which help in creating an inflammatory microenvironment and contribute to the various stages of cancer development, maintenance, and progression. The major tumor infiltrating immune cells of the tumor microenvironment include TAMs and TANs, which are either recruited peripherally or present as brain-resident macrophages (microglia) and support stroma for cancer cell expansion and invasion. These cells are highly plastic in nature and can be polarized into different phenotypes depending upon different types of stimuli. During neuroinflammation, glioma cells interact with TAMs and TANs, facilitating tumor cell proliferation, survival, and migration. Targeting inflammatory mediators along with the reprogramming of TAMs and TANs could be of great importance in glioma treatment and may delay disease progression. In addition, an inhibition of the key signaling pathways such as NF-κB, JAK/STAT, MAPK, PI3K/Akt/mTOR, and TLRs, which are activated during neuroinflammation and have an oncogenic role in glioblastoma (GBM), can exert more pronounced anti-glioma effects.

Roles of Neutrophils in Glioma and Brain Metastases

Neutrophils, which are the most abundant circulating leukocytes in humans, are the first line of defense against bacterial and fungal infections. Recent studies have reported the role and importance of neutrophils in cancers. Glioma and brain metastases are the most common malignant tumors of the brain. The tumor microenvironment (TME) in the brain is complex and unique owing to the brain-blood barrier or brain-tumor barrier, which may prevent drug penetration and decrease the efficacy of immunotherapy. However, there are limited studies on the correlation between brain cancer and neutrophils. This review discusses the origin and functions of neutrophils. Additionally, the current knowledge on the correlation between neutrophil-to-lymphocyte ratio and prognosis of glioma and brain metastases has been summarized. Furthermore, the implications of tumor-associated neutrophil (TAN) phenotypes and the functions of TANs have been discussed. Finally, the potential effects of various treatments on TANs and the ability of neutrophils to function as a nanocarrier of drugs to the brain TME have been summarized. However, further studies are needed to elucidate the complex interactions between neutrophils, other immune cells, and brain tumor cells.

Blood-Based Biomarkers for Glioma in the Context of Gliomagenesis: A Systematic Review

BACKGROUND

Gliomas are the most common and aggressive tumors of the central nervous system. A robust and widely used blood-based biomarker for glioma has not yet been identified. In recent years, a plethora of new research on blood-based biomarkers for glial tumors has been published. In this review, we question which molecules, including proteins, nucleic acids, circulating cells, and metabolomics, are most promising blood-based biomarkers for glioma diagnosis, prognosis, monitoring and other purposes, and align them to the seminal processes of cancer.

METHODS

The Pubmed and Embase databases were systematically searched. Biomarkers were categorized in the identified biomolecules and biosources. Biomarker characteristics were assessed using the area under the curve (AUC), accuracy, sensitivity and/or specificity values and the degree of statistical significance among the assessed clinical groups was reported.

RESULTS

7,919 references were identified: 3,596 in PubMed and 4,323 in Embase. Following screening of titles, abstracts and availability of full-text, 262 articles were included in the final systematic review. Panels of multiple biomarkers together consistently reached AUCs >0.8 and accuracies >80% for various purposes but especially for diagnostics. The accuracy of single biomarkers, consisting of only one measurement, was far more variable, but single microRNAs and proteins are generally more promising as compared to other biomarker types.

CONCLUSION

Panels of microRNAs and proteins are most promising biomarkers, while single biomarkers such as GFAP, IL-10 and individual miRNAs also hold promise. It is possible that panels are more accurate once these are involved in different, complementary cancer-related molecular pathways, because not all pathways may be dysregulated in cancer patients. As biomarkers seem to be increasingly dysregulated in patients with short survival, higher tumor grades and more pathological tumor types, it can be hypothesized that more pathways are dysregulated as the degree of malignancy of the glial tumor increases. Despite, none of the biomarkers found in the literature search seem to be currently ready for clinical implementation, and most of the studies report only preliminary application of the identified biomarkers. Hence, large-scale validation of currently identified and potential novel biomarkers to show clinical utility is warranted.

MDSC: Markers, development, states, and unaddressed complexity

Myeloid-derived suppressor cells (MDSCs) are one of the most discussed biological entities in immunology. While the context and classification of this group of cells has evolved, MDSCs most commonly describe cells arising during chronic inflammation, especially late-stage cancers, and are defined by their T cell immunosuppressive functions. This MDSC concept has helped explain myeloid phenomena associated with disease outcome, but currently lacks clear definitions and a unifying framework across pathologies. Here, we propose such a framework to classify MDSCs as discrete cell states based on activation signals in myeloid populations leading to suppressive modes characterized by specific, measurable effects. Developing this level of knowledge of myeloid states across pathological conditions may ultimately transform how disparate diseases are grouped and treated.

Comprehensive exploration of tumor mutational burden and immune infiltration in diffuse glioma

BACKGROUND

Immune checkpoint inhibitors (ICIs) have been used as a novel treatment for diffuse gliomas, but the efficacy varies with patients, which may be associated with the tumor mutational burden (TMB) and immune infiltration. We aimed to explore the relationship between the two and their impacts on the prognosis.

METHODS

The data of the training set were downloaded from The Cancer Genome Atlas (TCGA). "DESeq2" R package was used for differential analysis and identification of differentially expressed genes (DEGs). A gene risk score model was constructed based on DEGs, and a nomogram was developed combined with clinical features. With the CIBERSORT algorithm, the relationship between TMB and immune infiltration was analyzed, and an immune risk score model was constructed. Two models were verification in the validation set downloaded from the Chinese Glioma Genome Atlas (CGGA).

RESULTS

Higher TMB was related to worse prognosis, older age, higher grade, and higher immune checkpoint expression. The gene risk score model was constructed based on BIRC5, SAA1, and TNFRSF11B, and their expressions were all negatively correlated with prognosis. The nomogram was developed combined with age and grade. The immune risk score model was constructed based on M0 macrophages, neutrophils, naïve CD4⁺ T cells, and activated mast cells. The proportions of the first two were higher in the high-TMB group and correlated with worse prognosis, while the latter two were precisely opposite.

CONCLUSIONS

In diffuse gliomas, TMB was negatively correlated with prognosis. The association of immune infiltration with TMB and prognosis varied with the type of immune cells. The nomogram and risk score models can accurately predict prognosis. The results can help identify patients suitable for ICIs and potential therapeutic targets, thus improve the treatment of diffuse gliomas.

Uncovering the multifaceted roles played by neutrophils in allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a life-saving procedure used for the treatment of selected hematological malignancies, inborn errors of metabolism, and bone marrow failures. The role of neutrophils in alloHSCT has been traditionally evaluated only in the context of their ability to act as a first line of defense against infection. However, recent evidence has highlighted neutrophils as key effectors of innate and adaptive immune responses through a wide array of newly discovered functions. Accordingly, neutrophils are emerging as highly versatile cells that are able to acquire different, often opposite, functional capacities depending on the microenvironment and their differentiation status. Herein, we review the current knowledge on the multiple functions that neutrophils exhibit through the different stages of alloHSCT, from the hematopoietic stem cell (HSC) mobilization in the donor to the immunological reconstitution that occurs in the recipient following HSC infusion. We also discuss the influence exerted on neutrophils by the immunosuppressive drugs delivered in the course of alloHSCT as part of graft-versus-host disease (GVHD) prophylaxis. Finally, the potential involvement of neutrophils in alloHSCT-related complications, such as transplant-associated thrombotic microangiopathy (TA-TMA), acute and chronic GVHD, and cytomegalovirus (CMV) reactivation, is also discussed. Based on the data reviewed herein, the role played by neutrophils in alloHSCT is far greater than a simple antimicrobial role. However, much remains to be investigated in terms of the potential functions that neutrophils might exert during a highly complex procedure such as alloHSCT.

Macrophages and microglia: the cerberus of glioblastoma

Glioblastoma (GBM) is the most aggressive and deadliest of the primary brain tumors, characterized by malignant growth, invasion into the brain parenchyma, and resistance to therapy. GBM is a heterogeneous disease characterized by high degrees of both inter- and intra-tumor heterogeneity. Another layer of complexity arises from the unique brain microenvironment in which GBM develops and grows. The GBM microenvironment consists of neoplastic and non-neoplastic cells. The most abundant non-neoplastic cells are those of the innate immune system, called tumor-associated macrophages (TAMs). TAMs constitute up to 40% of the tumor mass and consist of both brain-resident microglia and bone marrow-derived myeloid cells from the periphery. Although genetically stable, TAMs can change their expression profiles based upon the signals that they receive from tumor cells; therefore, heterogeneity in GBM creates heterogeneity in TAMs. By interacting with tumor cells and with the other non-neoplastic cells in the tumor microenvironment, TAMs promote tumor progression. Here, we review the origin, heterogeneity, and functional roles of TAMs. In addition, we discuss the prospects of therapeutically targeting TAMs alone or in combination with standard or newly-emerging GBM targeting therapies.

Characterization of an endoplasmic reticulum stress-related signature to evaluate immune features and predict prognosis in glioma

Endoplasmic reticulum (ER) stress has considerable impact on cell growth, proliferation, metastasis, invasion, angiogenesis and chemoradiotherapy resistance in various cancers. However, the effect of ER stress on the outcomes of glioma patients remains unclear. In this study, we established an ER stress risk model based on The Cancer Genome Atlas (TCGA) glioma data set to reflect immune characteristics and predict the prognosis of glioma patients. Survival analysis indicated that there were significant differences in the overall survival (OS) of glioma patients with different ER stress-related risk scores. Moreover, the ER stress-related risk signature, which was markedly associated with the clinicopathological properties of glioma patients, could serve as an independent prognostic indicator. Functional enrichment analysis revealed that the risk model correlated with immune and inflammation responses, as well as biosynthesis and degradation. In addition, the ER stress-related risk model indicated an immunosuppressive microenvironment. In conclusion, we present an ER stress risk model that is an independent prognostic factor and indicates the general immune characteristics in the glioma microenvironment.

Polyamines drive myeloid cell survival by buffering intracellular pH to promote immunosuppression in glioblastoma

Glioblastoma is characterized by the robust infiltration of immunosuppressive tumor-associated myeloid cells (TAMCs). It is not fully understood how TAMCs survive in the acidic tumor microenvironment to cause immunosuppression in glioblastoma. Metabolic and RNA-seq analysis of TAMCs revealed that the arginine-ornithine-polyamine axis is up-regulated in glioblastoma TAMCs but not in tumor-infiltrating CD8+ T cells. Active de novo synthesis of highly basic polyamines within TAMCs efficiently buffered low intracellular pH to support the survival of these immunosuppressive cells in the harsh acidic environment of solid tumors. Administration of difluoromethylornithine (DFMO), a clinically approved inhibitor of polyamine generation, enhanced animal survival in immunocompetent mice by causing a tumor-specific reduction of polyamines and decreased intracellular pH in TAMCs. DFMO combination with immunotherapy or radiotherapy further enhanced animal survival. These findings indicate that polyamines are used by glioblastoma TAMCs to maintain normal intracellular pH and cell survival and thus promote immunosuppression during tumor evolution.

Myeloid Cells in Glioblastoma Microenvironment

Glioblastoma (GBM) is the most aggressive, malignant primary brain tumor in adults. GBM is notoriously resistant to immunotherapy mainly due to its unique immune microenvironment. High dimensional data analysis reveals the extensive heterogeneity of immune components making up the GBM microenvironment. Myeloid cells are the most predominant contributors to the GBM microenvironment; these cells are critical regulators of immune and therapeutic responses to GBM. Here, we will review the most recent advances on the characteristics and functions of different populations of myeloid cells in GBM, including bone marrow-derived macrophages, microglia, myeloid-derived suppressor cells, dendritic cells, and neutrophils. Epigenetic, metabolic, and phenotypic peculiarities of microglia and bone marrow-derived macrophages will also be assessed. The final goal of this review will be to provide new insights into novel therapeutic approaches for specific targeting of myeloid cells to improve the efficacy of current treatments in GBM patients.