Neutrophil Heterogeneity in Cancer: From Biology to Therapies

Single-cell RNA sequencing reveals immune cell dysfunction in the peripheral blood of patients with highly aggressive gastric cancer

Highly aggressive gastric cancer (HAGC) is a gastric cancer characterized by bone marrow metastasis and disseminated intravascular coagulation (DIC). Information about the disease is limited. Here we employed single-cell RNA sequencing to investigate peripheral blood mononuclear cells (PBMCs), aiming to unravel the immune response of patients toward HAGC. PBMCs from seven HAGC patients, six normal advanced gastric cancer (NAGC) patients, and five healthy individuals were analysed by single-cell RNA sequencing. The expression of genes of interest was validated by bulk RNA-sequencing and ELISA. We found a massive expansion of neutrophils in PBMCs of HAGC. These neutrophils are activated, but immature. Besides, mononuclear phagocytes exhibited an M2-like signature and T cells were suppressed and reduced in number. Analysis of cell-cell crosstalk revealed that several signalling pathways involved in neutrophil to T-cell suppression including APP-CD74, MIF-(CD74+CXCR2), and MIF-(CD74+CD44) pathways were increased in HAGC. NETosis-associated genes S100A8 and S100A9 as well as VEGF, PDGF, FGF, and NOTCH signalling that contribute to DIC development were upregulated in HAGC too. This study reveals significant changes in the distribution and interactions of the PBMC subsets and provides valuable insight into the immune response in patients with HAGC. S100A8 and S100A9 are highly expressed in HAGC neutrophils, suggesting their potential to be used as novel diagnostic and therapeutic targets for HAGC.

The Immune Response of Cutaneous Basosquamous- and Squamous-Cell Carcinoma Associated with Sun Exposure

In recent years, there has been an observed increase in the frequency of cutaneous carcinoma, which correlates with sun exposure. This study aims to explore the variances of tumor characteristics and immune response markers among patients diagnosed with cutaneous squamous-cell carcinoma (SCC) and basosquamous-cell carcinoma (BSC) with varying levels of sun exposure. The objective is to elucidate the potential influence of sun exposure on tumor progression and immune response in these types of carcinomas. We conducted a retrospective observational study that included 132 patients diagnosed with SCC and BSC. Participants were separated into high- and low-sun exposure groups. Tumor characteristics and immune response markers, including lymphocyte percentage (LY%), neutrophil-to-lymphocyte ratio (NLR), and lymphocyte-to-monocyte ratio (LMR), were assessed using the Mann-Whitney U test. Our findings revealed the interplay between sun exposure, inflammation, aging, and immune response. In 80% of cases, it was found that individuals had high sun exposure throughout their lifetime. Patients in the high sun exposure category had a significantly higher LY% than those with low sun exposure (24.22 ± 7.64 vs. 20.71 ± 8.10, p = 0.041). Also, the NLR was lower in patients with high sun exposure (3.08 ± 1.47 vs. 3.94 ± 2.43, p = 0.023). Regarding inflammatory markers, the erythrocyte sedimentation rate (ESR), LY%, NLR, and LMR showed significant differences between the two groups. Patients who were diagnosed with SCC had higher ESR values (p = 0.041), higher LY% (p = 0.037), higher NLR (p = 0.041), and lower LMR (p = 0.025). This study provides evidence supporting distinct tumor characteristics and immune response patterns in patients diagnosed with SCC and BSC with a high sun exposure history. These findings imply that sun exposure may contribute to tumor progression and influence the immune response in individuals with SCC and BSC.

Neutrophil Extracellular Traps in Breast Cancer: Roles in Metastasis and Beyond

Despite advances in the treatment of breast cancer, the disease continues to exhibit high global morbidity and mortality. The importance of neutrophils in cancer development has been increasingly recognized. Neutrophil extracellular traps (NETs) are web-like structures released into the extracellular space by activated neutrophils, serving as a potential antimicrobial mechanism for capturing and eliminating microorganisms. The roles played by NETs in cancer development have been a subject of intense research in the last decade. In breast cancer, current evidence suggests that NETs are involved in various stages of cancer development, particularly during metastasis. In this review, we try to provide an updated overview of the roles played by NETs in breast cancer metastasis. These include: 1) facilitating systemic dissemination of cancer cells; 2) promoting cancer-associated inflammation; 3) facilitating cancer-associated thrombosis; 4) facilitating pre-metastatic niche formation; and 5) awakening dormant cancer cells. The translational implications of NETs in breast cancer treatment are also discussed. Understanding the relationship between NETs and breast cancer metastasis is expected to provide important insights for developing new therapeutic strategies for breast cancer patients.

Immunity-on-a-Chip: Integration of Immune Components into the Scheme of Organ-on-a-Chip Systems

Studying the immune system in vitro aims to understand how, when, and where the immune cells migrate/differentiate and respond to the various triggering events and the decision points along the immune response journey. It becomes evident that organ-on-a-chip (OOC) technology has a superior capability to recapitulate the cell-cell and tissue-tissue interaction in the body, with a great potential to provide tools for tracking the paracrine signaling with high spatial-temporal precision and implementing in situ real-time, non-destructive detection assays, therefore, enabling extraction of mechanistic information rather than phenotypic information. However, despite the rapid development in this technology, integration of the immune system into OOC devices stays among the least navigated tasks, with immune cells still the major missing components in the developed models. This is mainly due to the complexity of the immune system and the reductionist methodology of the OOC modules. Dedicated research in this field is demanded to establish the understanding of mechanism-based disease endotypes rather than phenotypes. Herein, we systemically present a synthesis of the state-of-the-art of immune-cantered OOC technology. We comprehensively outlined what is achieved and identified the technology gaps emphasizing the missing components required to establish immune-competent OOCs and bridge these gaps.

Immune Thrombosis: Exploring the Significance of Immune Complexes and NETosis

Neutrophil extracellular traps (NETs) are major contributors to inflammation and autoimmunity, playing a key role in the development of thrombotic disorders. NETs, composed of DNA, histones, and numerous other proteins serve as scaffolds for thrombus formation and promote platelet activation, coagulation, and endothelial dysfunction. Accumulating evidence indicates that NETs mediate thrombosis in autoimmune diseases, viral and bacterial infections, cancer, and cardiovascular disease. This article reviews the role and mechanisms of immune complexes in NETs formation and their contribution to the generation of a prothrombotic state. Immune complexes are formed by interactions between antigens and antibodies and can induce NETosis by the direct activation of neutrophils via Fc receptors, via platelet activation, and through endothelial inflammation. We discuss the mechanisms by which NETs induced by immune complexes contribute to immune thrombotic processes and consider the potential development of therapeutic strategies. Targeting immune complexes and NETosis hold promise for mitigating thrombotic events and reducing the burden of immune thrombosis.

Fast and furious: The neutrophil and its armamentarium in health and disease

Neutrophils are powerful effector cells leading the first wave of acute host-protective responses. These innate leukocytes are endowed with oxidative and nonoxidative defence mechanisms, and play well-established roles in fighting invading pathogens. With microbicidal weaponry largely devoid of specificity and an all-too-well recognized toxicity potential, collateral damage may occur in neutrophil-rich diseases. However, emerging evidence suggests that neutrophils are more versatile, heterogeneous, and sophisticated cells than initially thought. At the crossroads of innate and adaptive immunity, neutrophils demonstrate their multifaceted functions in infectious and noninfectious pathologies including cancer, autoinflammation, and autoimmune diseases. Here, we discuss the kinetics of neutrophils and their products of activation from bench to bedside during health and disease, and provide an overview of the versatile functions of neutrophils as key modulators of immune responses and physiological processes. We focus specifically on those activities and concepts that have been validated with primary human cells.

miR-4780 Derived from N2-Like Neutrophil Exosome Aggravates Epithelial-Mesenchymal Transition and Angiogenesis in Colorectal Cancer

Despite significant advances in diagnostic methods and treatment strategies, the prognosis for patients with advanced colon cancer remains poor, and mortality rates are often high due to metastasis. Increasing evidence showed that it is of significant importance to investigate how the tumor microenvironment participates in the development of colorectal cancer (CRC). In this manuscript, neutrophils were sequentially stimulated with all-trans retinoic acid and transforming growth factor-β in turn to induce the neutrophil polarization. Differentially expressed miRNA in neutrophil exosomes have been sequenced by microarray profile, and the effect of N2-like neutrophil-derived exosomal miR-4780 on epithelial-mesenchymal transition (EMT) and angiogenesis was investigated. In our results, we found that neutrophils were enriched in CRC tumor tissue and that CD11b expression correlated with tumor site and serous membrane invasion. At the same time, we demonstrated that internalization of N2 exosomes exacerbated the viability, migration, and invasion of CRC cell lines and inhibited apoptosis. To further investigate the molecular mechanism, we analyzed the miRNA expression profile in the N2-like neutrophils, which led to the selection of hsa-miR-4780 for the subsequent experiment. The overexpression of miR-4780 from N2-like neutrophil-derived exosomes exacerbated EMT and angiogenesis. Moreover, miR-4780 can regulate its target gene SOX11 to effect EMT and angiogenesis in CRC cell lines. CRC with liver metastasis model also validated that aberrant expression of miR-4780 in N2-like neutrophil exosomes exacerbated tumor metastasis and development of tumor via EMT and angiogenesis. In conclusion, our current findings reveal an important mechanism by which mR-4780 from N2-like neutrophil exosomes exacerbates tumor metastasis and progression via EMT and angiogenesis.

Integrated Analysis Identifies DPP7 as a Prognostic Biomarker in Colorectal Cancer

Colorectal cancer has a poor prognosis and is prone to recurrence and metastasis. DPP7, a prolyl peptidase, is reported to regulate lymphocyte quiescence. However, the correlation of DPP7 with prognosis in CRC remains unclear. With publicly available cohorts, the Wilcoxon rank-sum test and logistic regression were employed to analyze the relationship between DPP7 expression and the clinicopathological features of CRC patients. Specific pathways of differentially expressed genes were determined through biofunctional analysis and gene set enrichment analysis (GSEA). qPCR and immunohistochemical staining were used to determine DPP7 expression levels in surgical specimens. The public dataset and analysis of the biospecimens of CRC patients revealed that DPP7, in the CRC samples, was expressed significantly higher than in non-tumor tissues. Moreover, increased DPP7 was significantly associated with a higher N stage, lymphatic invasion, and shorter overall survival. Functionally, DPP7 is involved in neuroactive ligand-receptor interaction and olfactory transduction signaling. We identified a series of targeted drugs and small-molecule drugs with responses to DPP7. To conclude, DPP7 is a valuable diagnostic and prognostic biomarker for CRC and considered as a new therapeutic target.

The double-edged role of neutrophil heterogeneity in inflammatory diseases and cancers

Neutrophils are important immune cells act as the body's first line of defense against infection and respond to diverse inflammatory cues. Many studies have demonstrated that neutrophils display plasticity in inflammatory diseases and cancers. Clarifying the role of neutrophil heterogeneity in inflammatory diseases and cancers will contribute to the development of novel treatment strategies. In this review, we have presented a review on the development of the understanding on neutrophil heterogeneity from the traditional perspective and a high-resolution viewpoint. A growing body of evidence has confirmed the double-edged role of neutrophils in inflammatory diseases and tumors. This may be due to a lack of precise understanding of the role of specific neutrophil subsets in the disease. Thus, elucidating specific neutrophil subsets involved in diseases would benefit the development of precision medicine. Thusly, we have summarized the relevance and actions of neutrophil heterogeneity in inflammatory diseases and cancers comprehensively. Meanwhile, we also discussed the potential intervention strategy for neutrophils. This review is intended to deepen our understanding of neutrophil heterogeneity in inflammatory diseases and cancers, while hold promise for precise treatment of neutrophil-related diseases.

Neutrophils in triple-negative breast cancer: an underestimated player with increasingly recognized importance

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer, with limited therapeutic options readily available. Immunotherapy such as immune checkpoint inhibition has been investigated in TNBC but still encounters low overall response. Neutrophils, the most abundant leukocytes in the body, are increasingly recognized as an active cancer-modulating entity. In the bloodstream, neutrophils escort circulating tumor cells to promote their survival and stimulate their proliferation and metastasis. In the tumor microenvironment, neutrophils modulate the immune milieu through polarization between the anti-tumor and the pro-tumor phenotypes. Through a comprehensive review of recently published literature, it is evident that neutrophils are an important player in TNBC immunobiology and can be used as an important prognostic marker of TNBC. Particularly, in their pro-tumor form, neutrophils facilitate TNBC metastasis through formation of neutrophil extracellular traps and the pre-metastatic niche. These findings will help advance the potential utilization of neutrophils as a therapeutic target in TNBC.

Prognostic value and model construction of preoperative inflammatory markers in patients with metastatic renal cell carcinoma

BACKGROUND

Inflammation is considered to be one of the driving factors of cancer, and chronic inflammation plays a crucial role in tumor growth and metastasis. The aim of this study was to examine the predictive value of preoperative inflammatory biomarkers for overall survival (OS) in patients with metastatic renal cell carcinoma (mRCC), including preoperative neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), and aspartate aminotransferase-to-lymphocyte ratio (ALR), a novel inflammatory biomarker.

METHOD

This study included 198 patients with mRCC from a single center from 2006 to 2022. The optimal cut-off levels for the three biomarkers were derived using the receiver operating characteristic curve (ROC). Cox univariate and multivariate analyses were used to assess independent prognostic inflammatory biomarkers. Finally, independent prognostic inflammatory biomarkers were incorporated into the prognostic model to establish a nomogram to predict the postoperative survival of patients with mRCC.

RESULT

The area under the ROC curve for NLR, LMR, and ALR, respectively, is 0.71 (CI: 0.635-0.784), 0.68 (CI: 0.604-0.755), and 0.75 (CI: 0.680-0.819). The optimal LMR, NLR, and ALR cut-off levels as evaluated by the ROC curve were 3.836, 3.106, and 68.056, respectively. Patients with NLR and ALR higher than the cut-off level and LMR lower than the cut-off level had a significant relationship with OS. Multivariate analysis revealed that tumor necrosis, lower LMR, and higher ALR were independent risk factors for OS. In addition, a nomogram that includes independent prognostic inflammatory biomarkers can accurately predict the OS in patients with mRCC.

CONCLUSION

ALR and LMR are independent risk factors for the prognosis of individuals with mRCC. By monitoring ALR and LMR postoperatively, the prognosis of patients with mRCC can be better evaluated.

Neutrophil extracellular traps induced by the hypoxic microenvironment in gastric cancer augment tumour growth

BACKGROUND

Inflammation-related predisposition to cancer plays an essential role in cancer progression and is associated with poor prognosis. A hypoxic microenvironment and neutrophil infiltration are commonly present in solid tumours, including gastric cancer (GC). Neutrophil extracellular traps (NETs) have also been demonstrated in the tumour immune microenvironment (TIME), but how NETs affect GC progression remains unknown. Here, we investigated the role of NET formation in the TIME and further explored the underlying mechanism of NETs in GC tumour growth.

METHODS

Hypoxia-induced factor-1α (HIF-1α), citrulline histone 3 (citH3) and CD66b expression in tumour and adjacent nontumor tissue samples was evaluated by western blotting, immunofluorescence and immunohistochemical staining. The expression of neutrophil-attracting chemokines in GC cells and their hypoxic-CM was measured by qRT‒PCR and ELISA. Neutrophil migration under hypoxic conditions was evaluated by a Transwell assay. Pathway activation in neutrophils in a hypoxic microenvironment were analysed by western blotting. NET formation was measured in vitro by immunofluorescence staining. The protumour effect of NETs on GC cells was identified by Transwell, wound healing and cell proliferation assays. In vivo, an lipopolysaccharide (LPS)-induced NET model and subcutaneous tumour model were established in BALB/c nude mice to explore the mechanism of NETs in tumour growth.

RESULTS

GC generates a hypoxic microenvironment that recruits neutrophils and induces NET formation. High mobility group box 1 (HMGB1) was translocated to the cytoplasm from the nucleus of GC cells in the hypoxic microenvironment and mediated the formation of NETs via the toll-like receptor 4 (TLR4)/p38 MAPK signalling pathway in neutrophils. HMGB1/TLR4/p38 MAPK pathway inhibition abrogated hypoxia-induced neutrophil activation and NET formation. NETs directly induced GC cell invasion and migration but not proliferation and accelerated the augmentation of GC growth by increasing angiogenesis. This rapid tumour growth was abolished by treatment with the NET inhibitor deoxyribonuclease I (DNase I) or a p38 MAPK signalling pathway inhibitor.

CONCLUSIONS

Hypoxia triggers an inflammatory response and NET formation in the GC TIME to augment tumour growth. Targeting NETs with DNase I or HMGB1/TLR4/p38 MAPK pathway inhibitors is a potential therapeutic strategy to inhibit GC progression. Video Abstract.

A computer vision approach for analyzing label free leukocyte trafficking dynamics on a microvascular mimetic

High-content imaging techniques in conjunction with in vitro microphysiological systems (MPS) allow for novel explorations of physiological phenomena with a high degree of translational relevance due to the usage of human cell lines. MPS featuring ultrathin and nanoporous silicon nitride membranes (µSiM) have been utilized in the past to facilitate high magnification phase contrast microscopy recordings of leukocyte trafficking events in a living mimetic of the human vascular microenvironment. Notably, the imaging plane can be set directly at the endothelial interface in a µSiM device, resulting in a high-resolution capture of an endothelial cell (EC) and leukocyte coculture reacting to different stimulatory conditions. The abundance of data generated from recording observations at this interface can be used to elucidate disease mechanisms related to vascular barrier dysfunction, such as sepsis. The appearance of leukocytes in these recordings is dynamic, changing in character, location and time. Consequently, conventional image processing techniques are incapable of extracting the spatiotemporal profiles and bulk statistics of numerous leukocytes responding to a disease state, necessitating labor-intensive manual processing, a significant limitation of this approach. Here we describe a machine learning pipeline that uses a semantic segmentation algorithm and classification script that, in combination, is capable of automated and label-free leukocyte trafficking analysis in a coculture mimetic. The developed computational toolset has demonstrable parity with manually tabulated datasets when characterizing leukocyte spatiotemporal behavior, is computationally efficient and capable of managing large imaging datasets in a semi-automated manner.

The Role of Different Immunocompetent Cell Populations in the Pathogenesis of Head and Neck Cancer-Regulatory Mechanisms of Pro- and Anti-Cancer Activity and Their Impact on Immunotherapy

Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive and heterogeneous groups of human neoplasms. HNSCC is characterized by high morbidity, accounting for 3% of all cancers, and high mortality with ~1.5% of all cancer deaths. It was the most common cancer worldwide in 2020, according to the latest GLOBOCAN data, representing the seventh most prevalent human malignancy. Despite great advances in surgical techniques and the application of modern combinations and cytotoxic therapies, HNSCC remains a leading cause of death worldwide with a low overall survival rate not exceeding 40-60% of the patient population. The most common causes of death in patients are its frequent nodal metastases and local neoplastic recurrences, as well as the relatively low response to treatment and severe drug resistance. Much evidence suggests that the tumour microenvironment (TME), tumour infiltrating lymphocytes (TILs) and circulating various subpopulations of immunocompetent cells, such regulatory T cells (CD4+CD25+Foxp3+Tregs), cytotoxic CD3+CD8+ T cells (CTLs) and CD3+CD4+ T helper type 1/2/9/17 (Th1/Th2/Th9/Th17) lymphocytes, T follicular helper cells (Tfh) and CD56dim/CD16bright activated natural killer cells (NK), carcinoma-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), tumour-associated neutrophils (N1/N2 TANs), as well as tumour-associated macrophages (M1/M2 phenotype TAMs) can affect initiation, progression and spread of HNSCC and determine the response to immunotherapy. Rapid advances in the field of immuno-oncology and the constantly growing knowledge of the immunosuppressive mechanisms and effects of tumour cancer have allowed for the use of effective and personalized immunotherapy as a first-line therapeutic procedure or an essential component of a combination therapy for primary, relapsed and metastatic HNSCC. This review presents the latest reports and molecular studies regarding the anti-tumour role of selected subpopulations of immunocompetent cells in the pathogenesis of HNSCC, including HPV+ve (HPV+) and HPV-ve (HPV-) tumours. The article focuses on the crucial regulatory mechanisms of pro- and anti-tumour activity, key genetic or epigenetic changes that favour tumour immune escape, and the strategies that the tumour employs to avoid recognition by immunocompetent cells, as well as resistance mechanisms to T and NK cell-based immunotherapy in HNSCC. The present review also provides an overview of the pre- and clinical early trials (I/II phase) and phase-III clinical trials published in this arena, which highlight the unprecedented effectiveness and limitations of immunotherapy in HNSCC, and the emerging issues facing the field of HNSCC immuno-oncology.

Association of Neutrophil-to-Lymphocyte Ratio with Nutrition in Patients with Various Types of Malignant Tumors: A Multicenter Cross-Sectional Study

Aim

Neutrophil-to-lymphocyte ratio (NLR) is an index of systemic inflammation. This study is to clarify the role of NLR in body functional status, nutritional risk and nutritional status in the course of tumor.

Methods

A multi-center cross-sectional study of patients with various types of malignant tumors was accrued from the whole country. There were 21,457 patients with completed clinical data, biochemical indicators, physical examination, the Patient-Generated Subjective Global Assessment (PG-SGA) and Nutrition Risk Screening 2002 (NRS2002) survey. Logistic regression analysis was used to figure out the influencing factors of NLR, and four models were established to evaluate the influence of NLR on body functions, nutritional risks and nutritional status.

Results

Male patients, TNM stage IV, total bilirubin, hypertension and coronary atherosclerotic heart disease (CAHD) were independent predictors of NLR >2.5. BMI, digestive systemic tumors and triglyceride negatively affect NLR in multivariable logistic regression. NLR was an independent predictor of Karnofsky Performance Scale (KPS), fat store deficit in all degrees, moderate and severe muscle deficit, mild fluid retention and PG-SGA grade.

Conclusion

Male patients and those with hypertension and CAHD are prone to systemic inflammation. Systemic inflammation significantly degrades body function status and nutritional status, increases nutritional risk and influences fat and muscle metabolism in patients with malignant tumor. Improving the intervenable indicators such as elevating albumin and pre-albumin, decreasing total bilirubin and enhancing nutrition support are imperative. Obesity and triglyceride behave like anti-systemic inflammation, which is misleading due to reverse causation in the course of malignancy.

Evaluation of innate and adaptive immune system interactions in the tumor microenvironment via a 3D continuum model

Immune cells in the tumor microenvironment (TME) are known to affect tumor growth, vascularization, and extracellular matrix (ECM) deposition. Marked interest in system-scale analysis of immune species interactions within the TME has encouraged progress in modeling tumor-immune interactions in silico. Due to the computational cost of simulating these intricate interactions, models have typically been constrained to representing a limited number of immune species. To expand the capability for system-scale analysis, this study develops a three-dimensional continuum mixture model of tumor-immune interactions to simulate multiple immune species in the TME. Building upon a recent distributed computing implementation that enables efficient solution of such mixture models, major immune species including monocytes, macrophages, natural killer cells, dendritic cells, neutrophils, myeloid-derived suppressor cells (MDSC), cytotoxic, helper, regulatory T-cells, and effector and regulatory B-cells and their interactions are represented in this novel implementation. Immune species extravasate from blood vasculature, undergo chemotaxis toward regions of high chemokine concentration, and influence the TME in proportion to locally defined levels of stimulation. The immune species contribute to the production of angiogenic and tumor growth factors, promotion of myofibroblast deposition of ECM, upregulation of angiogenesis, and elimination of living and dead tumor species. The results show that this modeling approach offers the capability for quantitative insight into the modulation of tumor growth by diverse immune-tumor interactions and immune-driven TME effects. In particular, MDSC-mediated effects on tumor-associated immune species' activation levels, volume fraction, and influence on the TME are explored. Longer term, linking of the model parameters to particular patient tumor information could simulate cancer-specific immune responses and move toward a more comprehensive evaluation of immunotherapeutic strategies.

Hypoxia induced lactate acidosis modulates tumor microenvironment and lipid reprogramming to sustain the cancer cell survival

It is well known that solid hypoxic tumour cells oxidise glucose through glycolysis, and the end product of this pathway is fermented into lactate which accumulates in the tumour microenvironment (TME). Initially, it was proclaimed that cancer cells cannot use lactate; therefore, they dump it into the TME and subsequently augment the acidity of the tumour milieu. Furthermore, the TME acts as a lactate sink with stope variable amount of lactate in different pathophysiological condition. Regardless of the amount of lactate pumped out within TME, it disappears immediately which still remains an unresolved puzzle. Recent findings have paved pathway in exploring the main role of lactate acidosis in TME. Cancer cells utilise lactate in the de novo fatty acid synthesis pathway to initiate angiogenesis and invasiveness, and lactate also plays a crucial role in the suppression of immunity. Furthermore, lactate re-programme the lipid biosynthetic pathway to develop a metabolic symbiosis in normoxic, moderately hypoxic and severely hypoxic cancer cells. For instance: severely hypoxic cancer cells enable to synthesizing poly unsaturated fatty acids (PUFA) in oxygen scarcity secretes excess of lactate in TME. Lactate from TME is taken up by the normoxic cancer cells whereas it is converted back to PUFAs after a sequence of reactions and then liberated in the TME to be utilized in the severely hypoxic cancer cells. Although much is known about the role of lactate in these biological processes, the exact molecular pathways that are involved remain unclear. This review attempts to understand the molecular pathways exploited by lactate to initiate angiogenesis, invasiveness, suppression of immunity and cause re-programming of lipid synthesis. This review will help the researchers to develop proper understanding of lactate associated bimodal regulations of TME.

Functional plasticity of neutrophils after low- or high-dose irradiation in cancer treatment - A mini review

Over the last several decades, radiotherapy has been considered the primary treatment option for a broad range of cancer types, aimed at prolonging patients' survival and slowing down tumor regression. However, therapeutic outcomes of radiotherapy remain limited, and patients suffer from relapse shortly after radiation. Neutrophils can initiate an immune response to infection by releasing cytokines and chemokines to actively combat pathogens. In tumor immune microenvironment, tumor-derived signals reprogram neutrophils and induce their heterogeneity and functional versatility to promote or inhibit tumor growth. In this review, we present an overview of the typical phenotypes of neutrophils that emerge after exposure to low- and high-dose radiation. These phenotypes hold potential for developing synergistic therapeutic strategies to inhibit immunosuppressive activity and improve the antitumor effects of neutrophils to render radiation therapy as a more effective strategy for cancer patients, through tumor microenvironment modulation.

Heterogeneity of neutrophils in cancer: one size does not fit all

Neutrophils play an essential role in the defense against bacterial infections and orchestrate both the innate and adaptive immune responses. With their abundant numbers, diverse function and short life span, these cells are at the forefront of immune responses, and have gained attention in recent years because of their presence in tumor sites. Neutrophil involvement pertains to tumor cells' ability to construct a suitable tumor microenvironment (TME) that accelerates their own growth and malignancy, by facilitating their interaction with surrounding cells through the circulatory and lymphatic systems, thereby influencing tumor development and progression. Studies have indicated both pro- and anti-tumor properties of infiltrating neutrophils. The TME can exploit neutrophil function, recruitment, and even production, thus resulting in pro-tumor properties of neutrophils, including promotion of genetic instability, tumor cell proliferation, angiogenesis and suppression of anti-tumor or inflammatory response. In contrast, neutrophils can mediate anti-tumor resistance by direct cytotoxicity to the tumor cells or by facilitating anti-tumor functions via crosstalk with T cells. Here, we summarize current knowledge regarding the effects of neutrophil heterogeneity under homeostatic and tumor conditions, including neutrophil phenotype and function, in cancer biology.

The Yin-Yang of myeloid cells in the leukemic microenvironment: Immunological role and clinical implications

The leukemic microenvironment has a high diversity of immune cells that are phenotypically and functionally distinct. However, our understanding of the biology, immunology, and clinical implications underlying these cells remains poorly investigated. Among the resident immune cells that can infiltrate the leukemic microenvironment are myeloid cells, which correspond to a heterogeneous cell group of the innate immune system. They encompass populations of neutrophils, macrophages, and myeloid-derived suppressor cells (MDSCs). These cells can be abundant in different tissues and, in the leukemic microenvironment, are associated with the clinical outcome of the patient, acting dichotomously to contribute to leukemic progression or stimulate antitumor immune responses. In this review, we detail the current evidence and the many mechanisms that indicate that the activation of different myeloid cell populations may contribute to immunosuppression, survival, or metastatic dissemination, as well as in immunosurveillance and stimulation of specific cytotoxic responses. Furthermore, we broadly discuss the interactions of tumor-associated neutrophils and macrophages (TANs and TAMs, respectively) and MDSCs in the leukemic microenvironment. Finally, we provide new perspectives on the potential of myeloid cell subpopulations as predictive biomarkers of therapeutical response, as well as potential targets in the chemoimmunotherapy of leukemias due to their dual Yin-Yang roles in leukemia.

Lack of SIRP-alpha reduces lung cancer growth in mice by promoting anti-tumour ability of macrophages and neutrophils

OBJECTIVES

Signal regulatory protein-alpha (SIRPα) is a transmembrane glycoprotein specifically expressed on myeloid cells. Blockade of SIRPα/CD47 interaction is effective in combinational therapy of some cancers. This study aimed to explore into the role and underlying molecular mechanisms of SIRPα in lung cancer growth.

MATERIALS AND METHODS

A mouse model with lung cancer in wild-type (WT) and SIRPα-knockout mouse (KO) mice was established by subcutaneous injection of Lewis murine lung cancer cells (LLC). Circulating monocytes and neutrophils were depleted in mice by intraperitoneal administration of clodronate liposomes and anti-Ly6G antibody, respectively. Phenotypes and phagocytosis of macrophages and neutrophils were analysed by flow cytometry. Transwell assay was used to analyse LLC cells migration and invasion.

RESULTS

Lack of SIRPα inhibited LLC cells growth in KO mice, associated with reduced infiltrating PD-1⁺ CD8⁺ T cells and production of IL-6 from infiltrating macrophages and neutrophils in tumour tissues. Depletion of circulating monocytes and neutrophils reduced LLC cells growth in WT mice, which was abolished in KO mice. Studies in vitro showed that lack of SIRPα increased M1/M2 ratio, and reduced LLC cell migration and invasion via attenuated IL-6 secretion. Lack of SIRPα expression in neutrophils effectively increased the cytotoxic activity to LLC cells in vitro.

CONCLUSIONS

Lack of SIRPα suppressed lung cancer cell growth in mice, dependent on circulating macrophages and neutrophils, in association with improved phagocytosis and reduced IL-6 expression.

Focus on organoids: cooperation and interconnection with extracellular vesicles - Is this the future of in vitro modeling?

Organoids are simplified in vitro model systems of organs that are used for modeling tissue development and disease, drug screening, cell therapy, and personalized medicine. Despite considerable success in the design of organoids, challenges remain in achieving real-life applications. Organoids serve as unique and organized groups of micro physiological systems that are capable of self-renewal and self-organization. Moreover, they exhibit similar organ functionality(ies) as that of tissue(s) of origin. Organoids can be designed from adult stem cells, induced pluripotent stem cells, or embryonic stem cells. They consist of most of the important cell types of the desired tissue/organ along with the topology and cell-cell interactions that are highly similar to those of an in vivo tissue/organ. Organoids have gained interest in human biomedical research, as they demonstrate high promise for use in basic, translational, and applied research. As in vitro models, organoids offer significant opportunities for reducing the reliance and use of experimental animals. In this review, we will provide an overview of organoids, as well as those intercellular communications mediated by extracellular vesicles (EVs), and discuss the importance of organoids in modeling a tumor immune microenvironment (TIME). Organoids can also be exploited to develop a better understanding of intercellular communications mediated by EVs. Also, organoids are useful in mimicking TIME, thereby offering a better-controlled environment for studying various associated biological processes and immune cell types involved in tumor immunity, such as T-cells, macrophages, dendritic cells, and myeloid-derived suppressor cells, among others.

Engineered exosomes for studies in tumor immunology

Exosomes are a type of extracellular vesicle (EV) with diameters of 30-150 nm secreted by most of the cells into the extracellular spaces and can alter the microenvironment through cell-to-cell interactions by fusion with the plasma membrane and subsequent endocytosis and release of the cargo. Because of their biocompatibility, low toxicity and immunogenicity, permeability (even through the blood-brain barrier (BBB)), stability in biological fluids, and ability to accumulate in the lesions with higher specificity, investigators have started making designer's exosomes or engineered exosomes to carry biologically active protein on the surface or inside the exosomes as well as using exosomes to carry drugs, micro RNA, and other products to the site of interest. In this review, we have discussed biogenesis, markers, and contents of various exosomes including exosomes of immune cells. We have also discussed the current methods of making engineered and designer's exosomes as well as the use of engineered exosomes targeting different immune cells in the tumors, stroke, as well as at peripheral blood. Genetic engineering and customizing exosomes create an unlimited opportunity to use in diagnosis and treatment. Very little use has been discovered, and we are far away to reach its limits.

Multifaceted role of chemokines in solid tumors: From biology to therapy

Chemokines are small secretory chemotactic cytokines that control the directed migration of immune cells. Chemokines are involved in both anti-and pro-tumorigenic immune responses. Accumulating evidence suggests that the balance between these responses is influenced by several factors such as the stage of tumorigenesis, immune cell activation, recruitment of immune activating or immunosuppressive cells in the tumor microenvironment (TME), and chemokine receptor expression on effector and regulatory target cells. Cancer cells engage in a complex network with their TME components via several factors including growth factors, cytokines and chemokines that are critical for the growth of primary tumor and metastasis. However, chemokines show a multifaceted role in tumor progression including maintenance of stem-like properties, tumor cell proliferation/survival/senescence, angiogenesis, and metastasis. The heterogeneity of solid tumors in primary and metastatic cancers presents a challenge to the development of successful cancer therapy. Despite extensive research on how solid tumors escape immune cell-mediated anti-tumor response, finding an effective therapy for metastatic cancer still remains a challenge. This review discusses the multifarious roles of chemokines in solid tumors including various chemokine signaling pathways such as CXCL8-CXCR1/2, CXCL9, 10, 11-CXCR3, CXCR4-CXCL12, CCL(X)-CCR(X) in primary and metastatic cancers. We further discuss the novel therapeutic approaches that have been developed by major breakthroughs in chemokine research to treat cancer patients by the strategic blockade/activation of these signaling axes alone or in combination with immunotherapies.

Computational recognition of LncRNA signatures in tumor-associated neutrophils could have implications for immunotherapy and prognostic outcome of non-small cell lung cancer

Cancer immune function and tumor microenvironment are governed by long noncoding RNAs (lncRNAs). Nevertheless, it has yet to be established whether lncRNAs play a role in tumor-associated neutrophils (TANs). Here, a computing framework based on machine learning was used to identify neutrophil-specific lncRNA with prognostic significance in squamous cell carcinoma and lung adenocarcinoma using univariate Cox regression to comprehensively analyze immune, lncRNA, and clinical characteristics. The risk score was determined using LASSO Cox regression analysis. Meanwhile, we named this risk score as “TANlncSig.” TANlncSig was able to distinguish between better and worse survival outcomes in various patient datasets independently of other clinical variables. Functional assessment of TANlncSig showed it is a marker of myeloid cell infiltration into tumor infiltration and myeloid cells directly or indirectly inhibit the anti-tumor immune response by secreting cytokines, expressing immunosuppressive receptors, and altering metabolic processes. Our findings highlighted the value of TANlncSig in TME as a marker of immune cell infiltration and showed the values of lncRNAs as indicators of immunotherapy.

Granulocyte Apheresis: Can It Be Associated with Anti PD-1 Therapy for Melanoma?

In the field of advanced melanoma, there is an urgent need to investigate novel approaches targeting specific components of the cancer–immunity cycle beyond immune checkpoint inhibitors. The authors reviewed the basic understanding of the role of neutrophils in cancer biology, and the latest clinical evidence supporting the correlation between cancer-associated neutrophils and the prognosis and response to the immunotherapy of advanced melanoma. Finally, they propose that granulocyte and monocyte apheresis, an emerging non-pharmacological treatment in current dermatology, could become an investigative treatment targeting melanoma-associated neutrophils which could be potentially used in combination with the usual immune checkpoint inhibitors.

Neutrophils: Musketeers against immunotherapy

Neutrophils, the most copious leukocytes in human blood, play a critical role in tumorigenesis, cancer progression, and immune suppression. Recently, neutrophils have attracted the attention of researchers, immunologists, and oncologists because of their potential role in orchestrating immune evasion in human diseases including cancer, which has led to a hot debate redefining the contribution of neutrophils in tumor progression and immunity. To make this debate fruitful, this review seeks to provide a recent update about the contribution of neutrophils in immune suppression and tumor progression. Here, we first described the molecular pathways through which neutrophils aid in cancer progression and orchestrate immune suppression/evasion. Later, we summarized the underlying molecular mechanisms of neutrophil-mediated therapy resistance and highlighted various approaches through which neutrophil antagonism may heighten the efficacy of the immune checkpoint blockade therapy. Finally, we have highlighted several unsolved questions and hope that answering these questions will provide a new avenue toward immunotherapy revolution.

Engineering chimeric antigen receptor neutrophils from human pluripotent stem cells for targeted cancer immunotherapy

Neutrophils, the most abundant white blood cells in circulation, are closely related to cancer development and progression. Healthy primary neutrophils present potent cytotoxicity against various cancer cell lines through direct contact and via generation of reactive oxygen species. However, due to their short half-life and resistance to genetic modification, neutrophils have not yet been engineered with chimeric antigen receptors (CARs) to enhance their antitumor cytotoxicity for targeted immunotherapy. Here, we genetically engineered human pluripotent stem cells with synthetic CARs and differentiated them into functional neutrophils by implementing a chemically defined platform. The resulting CAR neutrophils present superior and specific cytotoxicity against tumor cells both in vitro and in vivo. Collectively, we established a robust platform for massive production of CAR neutrophils, paving the way to myeloid cell-based therapeutic strategies that would boost current cancer-treatment approaches.

Neutrophils are important innate immune cells that mediate both protumor and antitumor activities. Chang et al. genetically engineer human pluripotent stem cells to produce chimeric antigen receptor (CAR) neutrophils that display superior antitumor activities and improve survival in an in situ glioblastoma xenograft model.

Melanoma Stem Cells Educate Neutrophils to Support Cancer Progression

Simple Summary

In melanoma patients, poor prognosis often correlates with high presence of cancer-associated neutrophils, indicating that tumors can recruit these immune cells to specifically sustain their own development and progression. However, the role of cancer stem cells (CSCs) in this dialogue has not been elucidated yet. Our results revealed that melanoma SCs can reshape the immune microenvironment by triggering a pro-tumor N2 phenotype in neutrophils, which in turn are able to confer stemness properties to melanoma cells.

Abstract

Background: It is now well-established that cancer stem cells (CSCs) can support melanoma progression by reshaping the tumor immune microenvironment. However, the molecular mechanisms underlying the crosstalk between melanoma SCs and cancer-associated neutrophils have not been elucidated yet. Methods: The aim of the present study was to unravel the role of melanoma SCs in neutrophil polarization. HL60 neutrophil-like (dHL60) cells were treated with conditioned medium from A375 melanoma SCs (CSC-CM), and their phenotype was investigated. Results: We demonstrated that CSC-CM could specifically activate immune cells by increasing CD66b and CD11b expression. In particular, we revealed that A375 CSCs could release various soluble factors, namely TGF-β, IL-6, and IL-8, able to promote the recruitment of neutrophils and their switch toward an N2 phenotype characterized by the activation of ERK, STAT3, and P38 pathways and the overexpression of CXCR2 and NF-kB. Moreover, after exposure to CSC-CM, dHL60 cells exhibited enhanced ROS production and NET release, without undergoing cell death; increased secretion of MMP-9 and pro-inflammatory cytokines was also observed. Finally, CSC-CM-activated neutrophils endowed A375 cells with stemness traits, stimulating both sphere formation and ABCG2 expression. Conclusion: Collectively, our results suggest that melanoma SCs can prime neutrophils to support cancer progression.

G-CSF/GM-CSF-induced hematopoietic dysregulation in the progression of solid tumors

There are two types of abnormal hematopoiesis in solid tumor occurrence and treatment: pathological hematopoiesis, and myelosuppression induced by radiotherapy and chemotherapy. In this review, we primarily focus on the abnormal pathological hematopoietic differentiation in cancer induced by tumor-released granulocyte colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF). As key factors in hematopoietic development, G-CSF/GM-CSF are well-known facilitators of myelopoiesis and mobilization of hematopoietic stem cells (HSCs). In addition, these two cytokines can also promote or inhibit tumors, dependent on tumor type. In multiple cancer types, hematopoiesis is greatly enhanced and abnormal lineage differentiation is induced by these two cytokines. Here, dysregulated hematopoiesis induced by G-CSF/GM-CSF in solid tumors and its mechanism are summarized, and the prognostic value of G-CSF/GM-CSF-associated dysregulated hematopoiesis for tumor metastasis is also briefly highlighted.

Immunomodulatory Properties of Immune Checkpoint Inhibitors-More than Boosting T-Cell Responses?

The approval of immune checkpoint inhibitors (ICI) that serve to enhance effector T-cell anti-tumor responses has strongly improved success rates in the treatment of metastatic melanoma and other tumor types. The currently approved ICI constitute monoclonal antibodies blocking cytotoxic T-lymphocyte-associated protein (CTLA)-4 and anti-programmed cell death (PD)-1. By this, the T-cell-inhibitory CTLA-4/CD80/86 and PD-1/PD-1L/2L signaling axes are inhibited. This leads to sustained effector T-cell activity and circumvents the immune evasion of tumor cells, which frequently upregulate PD-L1 expression and modulate immune checkpoint molecule expression on leukocytes. As a result, profound clinical responses are observed in 40-60% of metastatic melanoma patients. Despite the pivotal role of T effector cells for triggering anti-tumor immunity, mounting evidence indicates that ICI efficacy may also be attributable to other cell types than T effector cells. In particular, emerging research has shown that ICI also impacts innate immune cells, such as myeloid cells, natural killer cells and innate lymphoid cells, which may amplify tumoricidal functions beyond triggering T effector cells, and thus improves clinical efficacy. Effects of ICI on non-T cells may additionally explain, in part, the character and extent of adverse effects associated with treatment. Deeper knowledge of these effects is required to further develop ICI treatment in terms of responsiveness of patients to treatment, to overcome resistance to ICI and to alleviate adverse effects. In this review we give an overview into the currently known immunomodulatory effects of ICI treatment in immune cell types other than the T cell compartment.

Gene signature of circulating platelet‐bound neutrophils is associated with poor prognosis in cancer patients

Beyond their critical role in hemostasis, platelets physically interact with neutrophils to form neutrophil‐platelet aggregates (NPAs), enhancing neutrophil effector functions during inflammation. NPAs may also promote disease worsening in various inflammatory diseases. However, characterization of NPAs in cancer remains totally unexplored. Using ImageStreamX (ISX) imaging flow cytometer, we were not only allowed able to detect CD15⁺ CD14⁻ CD36⁺ ITGA2B⁺ NPAs in both healthy donors' (HDs) and cancer patients' bloods, but we also showed that NPAs result from the binding of platelets preferentially to low‐density neutrophils (LDNs) as opposed to normal‐density neutrophils (NDNs). By reanalyzing two independent public scRNAseq data of whole blood leukocytes from cancer patients and HDs, we could identify a subset of neutrophils with high platelet gene expression that may correspond to NPAs. Moreover, we showed that cancer patients' derived NPAs possessed a distinct molecular signature compared to the other neutrophil subsets, independently of platelet genes. Gene ontology (GO) term enrichment analysis of this NPAs‐associated neutrophil transcriptomic signature revealed a significant enrichment of neutrophil degranulation, chemotaxis and trans‐endothelial migration GO terms. Lastly, using The Cancer Genome Atlas (TCGA), we could show by multivariate Cox analysis that the NPAs‐associated neutrophil transcriptomic signature was associated with a worse patient prognosis in several cancer types. These results suggest that neutrophils from NPAs are systemically primed by platelets empowering them with cancer progression capacities once at tumor site. NPAs may therefore hold clinical utility as novel noninvasive blood prognostic biomarker in cancer patients with solid tumors.

Preoperative Breast Immune Prognostic Index as Prognostic Factor Predicts the Clinical Outcomes of Breast Cancer Patients Receiving Neoadjuvant Chemotherapy

Objective

This study aims at investigating the potential prognostic significance of the breast immune prognostic index (BIPI) in breast cancer patients who received neoadjuvant chemotherapy (NACT).

Methods

The optimal cutoff value was calculated through the receiver operating characteristic curve (ROC). The correlations between BIPI and clinicopathologic characteristics were determined by the chi-square test or Fisher’s exact test. The Kaplan–Meier method was used to estimate the survival probability, and the log-rank test was used to analyze the differences in the survival probability among patients. The univariate and multivariate Cox proportional hazard regression model was used to screen the independent prognostic factors. A prognostic nomogram for disease-free survival (DFS) and overall survival (OS) was built on the basis of the multivariate analyses. Furthermore, the calibration curve and decision curve analysis (DCA) were used to assess the predictive performance of the nomogram.

Results

All enrolled patients were split into three subgroups based on the BIPI score. The mean DFS and OS of the BIPI score 0 group and BIPI score 1 group were significantly longer than those of the BIPI score 2 group (42.02 vs. 38.61 vs. 26.01 months, 77.61 vs. 71.83 vs. 53.15 months; p < 0.05). Univariate and multivariate analyses indicated that BIPI was an independent prognostic factor for patients’ DFS and OS (DFS, hazard ratio (HR): 6.720, 95% confidence interval (CI): 1.629–27.717; OS, HR: 8.006, 95% CI: 1.638–39.119). A nomogram with a C-index of 0.873 (95% CI: 0.779–0.966) and 0.801 (95% CI: 0.702–0.901) had a favorable performance for predicting DFS and OS survival rates for clinical use by combining immune scores with other clinical features. The calibration curves at 1-, 3-, and 5-year survival suggested a good consistency between the predicted and actual DFS and OS probability. The DCA demonstrated that the constructed nomogram had better clinical predictive usefulness than only BIPI in predictive clinical applications of 5-year DFS and OS prognostic assessments.

Conclusions

The patients with low BIPI score have better prognoses and longer DFS and OS. Furthermore, the BIPI-based nomogram may serve as a convenient prognostic tool for breast cancer and help in clinical decision-making.

Neutrophils in chronic inflammatory diseases

Chronic inflammation is a component of many disease conditions that affect a large group of individuals worldwide. Chronic inflammation is characterized by persistent, low-grade inflammation and is increased in the aging population. Neutrophils are normally the first responders to acute inflammation and contribute to the resolution of inflammation. However, in chronic inflammation, the role of neutrophils is less well understood and has been described as either beneficial or detrimental, causing tissue damage and enhancing the immune response. Emerging evidence suggests that neutrophils are important players in several chronic diseases, such as atherosclerosis, diabetes mellitus, nonalcoholic fatty liver disease and autoimmune disorders. This review will highlight the interaction of neutrophils with other cells in the context of chronic inflammation, the contribution of neutrophils to selected chronic inflammatory diseases, and possible future therapeutic strategies.

Neutrophils, Cancer and Thrombosis: The New Bermuda Triangle in Cancer Research

Spontaneous venous thrombosis is often the first clinical sign of cancer, and it is linked to a worsened survival rate. Traditionally, tumor-cell induced platelet activation has been the main actor studied in cancer-associated-thrombosis. However, platelet involvement alone does not seem to be sufficient to explain this heightened pro-thrombotic state. Neutrophils are emerging as key players in both thrombus generation and cancer progression. Neutrophils can impact thrombosis through the release of pro-inflammatory cytokines and expression of molecules like P-selectin and Tissue Factor (TF) on their membrane and on neutrophil-derived microvesicles. Their role in cancer progression is evidenced by the fact that patients with high blood-neutrophil counts have a worsened prognosis. Tumors can attract neutrophils to the cancer site via pro-inflammatory cytokine secretions and induce a switch to pro-tumoral (or N2) neutrophils, which support metastatic spread and have an immunosuppressive role. They can also expel their nuclear contents to entrap pathogens forming Neutrophil Extracellular Traps (NETs) and can also capture coagulation factors, enhancing the thrombus formation. These NETs are also known to have pro-tumoral effects by supporting the metastatic process. Here, we strived to do a comprehensive literature review of the role of neutrophils as drivers of both cancer-associated thrombosis (CAT) and cancer progression.

Single-Cell RNA Sequencing in Lung Cancer: Revealing Phenotype Shaping of Stromal Cells in the Microenvironment

The lung tumor microenvironment, which is composed of heterogeneous cell populations, plays an important role in the progression of lung cancer and is closely related to therapeutic efficacy. Increasing evidence has shown that stromal components play a key role in regulating tumor invasion, metastasis and drug resistance. Therefore, a better understanding of stromal components in the tumor microenvironment is helpful for the diagnosis and treatment of lung cancer. Rapid advances in technology have brought our understanding of disease into the genetic era, and single-cell RNA sequencing has enabled us to describe gene expression profiles with unprecedented resolution, enabling quantitative analysis of gene expression at the single-cell level to reveal the correlations among heterogeneity, signaling pathways, drug resistance and microenvironment molding in lung cancer, which is important for the treatment of this disease. In this paper, several common single-cell RNA sequencing methods and their advantages and disadvantages are briefly introduced to provide a reference for selection of suitable methods. Furthermore, we review the latest progress of single-cell RNA sequencing in the study of stromal cells in the lung tumor microenvironment.

Differential blood leukocyte populations based on individual variances and age

Blood was collected from the New York State Department of Health (NYSDOH) employees to assess variances in leukocyte numbers in January, May, and September throughout a year and over many years. Women and men of ages 20 to 80 volunteered to donate for this program. Most of the blood came from healthy individuals, and many remained healthy throughout the years of their blood donations. The major objective was to determine the extent that blood leukocyte numbers change so that transient vs more lingering changes may be helpful in assessing health status. Since some donors remained in the program for 14 years, age influences over time could be determined. Within a short period of 2-3 years, the flow cytometric immunophenotypic profile of blood lymphocyte is relatively stable with a CV% of < 20%. However, as humans age, the blood CD3⁺ T cell, CD8⁺ T cell, B cell, NKT cell, and CD4^-/CD8^- double-negative T cell (DN-T cell) subsets declined in cell numbers/μL, but the double-positive CD4⁺/CD8⁺ T cells (DP-T cells) increased in numbers. The extent and chronology of a variance, e.g., a subset exceeding its 75th or 90th percentile, might be indicative of a transient or chronic physiological or psychosocial stress affecting health or a developing pathology; however, because of the wide ranges of cell numbers/μL for each subset among individuals reported as healthy, everyone's immunity and health must be carefully evaluated. A CD4 to CD8 ratio (4/8R) of < 1 has been used to define an immunodeficiency such as HIV-induced AIDS, but a high 4/8R is less well associated with health status. A high 4/8R or granulocyte to lymphocyte ratio (GLR) might be an indicator of a stress, infection, or immune-related pathology. Sporadic and longitudinal increases of GLRs are reported. The results suggest that there are some age and sex differences in leukocyte numbers; stress influences on the blood profile of leukocytes likely exist. However, some values exceeding 2 standard deviations from means do not necessarily predict a health concern, whereas a longitudinal increase or decline might be indicative of a need for further evaluations.

Polymorphonuclear Neutrophils in Rheumatoid Arthritis and Systemic Lupus Erythematosus: More Complicated Than Anticipated

Polymorphonuclear neutrophils (PMN) are the most abundant leucocytes in the circulation in humans. They represent a heterogeneous population exerting diverse functions through several activities. Usually described as typical pro-inflammatory cells, immunomodulatory properties of PMNs have been reported. Among others, once activated and depending on the stimulus, PMNs expel neutrophil extracellular traps (NET) in the extracellular space. NETs are complexes made of DNA and granule proteins representing an innate immune mechanism fighting infections. Nevertheless, an excess of NET formation might be involved in the development of inflammatory or autoimmune responses. Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are two chronic, inflammatory, autoimmune diseases of unknown etiology and affecting mostly women. Several abnormal or non-classical functions of PMNs or PMN sub-populations have been described in SLE and RA. Particularly, NETs have been suggested to trigger pro-inflammatory responses by exposing pro-inflammatory mediators. Likewise, NETs may be the targets of autoantibodies or even might trigger the development of autoantibodies by exposing autoantigens. In the present review, we will summarize heterogeneous properties of human PMNs and we will discuss recent evidence linking PMNs and NETs to the pathogenesis of both SLE and RA.

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.

Actionable tests and treatments for patients with gastrointestinal cancers and historically short median survival times

BACKGROUND

Patients have difficult unmet needs when standard chemotherapy produces a median survival of less than 1 year or many patients will experience severe toxicities. Blood tests can predict their survival.

METHODS

Analyses evaluate predictive blood tests to identify patients who often survive 1 and 2 years. A four-test model includes: albumin, absolute neutrophil count, neutrophil-lymphocyte ratio, and lymphocyte-monocyte ratio. Individual tests include: alkaline phosphatase, lymphocytes, white blood count, platelet count, and hemoglobin. Eligible patients have advanced: resistant 3rd line colorectal, and both resistant and new pancreatic and intrahepatic bile duct cancers. Eligibility characteristics include: biopsy-proven, measurable metastatic disease, NCI grade 0-2 blood tests, Karnofsky Score 100-50, and any adult age. Drugs are given at 1/4-1/3 of their standard dosages biweekly: gemcitabine, irinotecan, fluorouracil, leucovorin, and day 2 oxaliplatin every 2 weeks. In case of progression, Docetaxel is added (except colon cancer), with or without Mitomycin C, and next cetuximab (except pancreatic and KRAS BRAF mutation cancers). Bevacizumab is substituted for cetuximab in case of another progression or ineligibility. Consent was written and conforms with Helsinki, IRB, and FDA criteria (FDA #119005).

RESULTS

Median survival is 14.5 months. Of 205 patients, 60% survive 12, and 37% survive 24 months (95% CI ± 8%). Survival is > 24, 13, and 3.8 months for patients with 0, 1-2, and 3-4 unfavorable tests, respectively. Individual "favorable and unfavorable" tests predict long and short survival. Neither age nor prior therapy discernibly affects survival. Net rates of clinically significant toxicities are less than 5%.

CONCLUSION

Treatments reproduce predictable, greater than 12 and 24-month chances of survival for the aged and for patients with drug-resistant tumors. Evaluation of blood tests may change practice, expand eligibility, and personalize treatments. Findings support investigation of drug combinations and novel dosages to reverse resistance and improve safety.

The Emerging Role of Neutrophil Extracellular Traps in Arterial, Venous and Cancer-Associated Thrombosis

Neutrophils play a vital role in the formation of arterial, venous and cancer-related thrombosis. Recent studies have shown that in a process known as NETosis, neutrophils release proteins and enzymes complexed to DNA fibers, collectively called neutrophil extracellular traps (NETs). Although NETs were originally described as a way for the host to capture and kill bacteria, current knowledge indicates that NETs also play an important role in thrombosis. According to recent studies, the destruction of vascular microenvironmental homeostasis and excessive NET formation lead to pathological thrombosis. In vitro experiments have found that NETs provide skeletal support for platelets, red blood cells and procoagulant molecules to promote thrombosis. The protein components contained in NETs activate the endogenous coagulation pathway to promote thrombosis. Therefore, NETs play an important role in the formation of arterial thrombosis, venous thrombosis and cancer-related thrombosis. This review will systematically summarize and explain the study of NETs in thrombosis in animal models and in vivo experiments to provide new targets for thrombosis prevention and treatment.

Multifaceted Roles of Chemokines and Chemokine Receptors in Tumor Immunity

Simple Summary

Various immune cells are involved in host immune responses to cancer. T-helper (Th) 1 cells, cytotoxic CD8⁺ T cells, and natural killer cells are the major effector cells in anti-tumor immunity, whereas cells such as regulatory T cells and myeloid-derived suppressor cells are negatively involved in anti-tumor immunity. Th2 cells and Th17 cells have been shown to have both pro-tumor and anti-tumor activities. The migratory properties of various immune cells are essential for their function and critically regulated by the chemokine superfamily. In this review, we summarize the roles of various immune cells in tumor immunity and their migratory regulation by the chemokine superfamily. We also assess the therapeutic possibilities of targeting chemokines and chemokine receptors in cancer immunotherapy.

Abstract

Various immune cells are involved in host tumor immune responses. In particular, there are many T cell subsets with different roles in tumor immunity. T-helper (Th) 1 cells are involved in cellular immunity and thus play the major role in host anti-tumor immunity by inducing and activating cytotoxic T lymphocytes (CTLs). On the other hand, Th2 cells are involved in humoral immunity and suppressive to Th1 responses. Regulatory T (Treg) cells negatively regulate immune responses and contribute to immune evasion of tumor cells. Th17 cells are involved in inflammatory responses and may play a role in tumor progression. However, recent studies have also shown that Th17 cells are capable of directly inducting CTLs and thus may promote anti-tumor immunity. Besides these T cell subsets, there are many other innate immune cells such as dendritic cells (DCs), natural killer (NK) cells, and myeloid-derived suppressor cells (MDSCs) that are involved in host immune responses to cancer. The migratory properties of various immune cells are critical for their functions and largely regulated by the chemokine superfamily. Thus, chemokines and chemokine receptors play vital roles in the orchestration of host immune responses to cancer. In this review, we overview the various immune cells involved in host responses to cancer and their migratory properties regulated by the chemokine superfamily. Understanding the roles of chemokines and chemokine receptors in host immune responses to cancer may provide new therapeutic opportunities for cancer immunotherapy.

Immune cell landscape and immunotherapy of medulloblastoma

Medulloblastoma is the most common primary pediatric malignancy of the central nervous system. Recurrent and refractory patients account for approximately 30% of them. Immune cells are an important component of the brain tumor microenvironment, including tumor-associated macrophages, T lymphocytes, natural killer cells, dendritic cells, neutrophils and B lymphocytes. Understanding how they behave and interact is important in the investigation of the onset and progression of medulloblastoma. Here, we overview the features and recent advances of each component of immune cells in medulloblastoma. Meanwhile, immunotherapy is a promising but also challenging treatment strategy for medulloblastoma. At present, there are a growing number of immunotherapeutic approaches under investigation including immune checkpoint inhibitors, oncolytic viruses, cancer vaccines, chimeric antigen receptor T cell therapies, and natural killer cells in recurrent and refractory medulloblastoma patients.

The Role of Innate Immune Cells in Tumor Invasion and Metastasis

Simple Summary

Tumor invasion and metastasis are one of the main reasons patients succumb to cancer. In this review, we summarize recent studies which provide evidence on the involvement of cells of the innate immune system and their function in invasion and metastasis.

Abstract

Metastasis is considered one of the hallmarks of cancer and enhanced tumor invasion and metastasis is significantly associated with cancer mortality. Metastasis occurs via a series of integrated processes involving tumor cells and the tumor microenvironment. The innate immune components of the microenvironment have been shown to engage with tumor cells and not only regulate their proliferation and survival, but also modulate the surrounding environment to enable cancer progression. In the era of immune therapies, it is critical to understand how different innate immune cell populations are involved in this process. This review summarizes recent literature describing the roles of innate immune cells during the tumor metastatic cascade.

G-CSF, the guardian of granulopoiesis

A considerable amount of continuous proliferation and differentiation is required to produce daily a billion new neutrophils in an adult human. Of the few cytokines and factors known to control neutrophil production, G-CSF is the guardian of granulopoiesis. G-CSF/CSF3R signaling involves the recruitment of non-receptor protein tyrosine kinases and their dependent signaling pathways of serine/threonine kinases, tyrosine phosphatases, and lipid second messengers. These pathways converge to activate the families of STAT and C/EBP transcription factors. CSF3R mutations are associated with human disorders of neutrophil production, including severe congenital neutropenia, neutrophilia, and myeloid malignancies. More than three decades after their identification, cloning, and characterization of G-CSF and G-CSF receptor, fundamental questions remain about their physiology.

Fluorescent Multiplex Immunohistochemistry Coupled With Other State-Of-The-Art Techniques to Systematically Characterize the Tumor Immune Microenvironment

Our expanding knowledge of the interactions between tumor cells and their microenvironment has helped to revolutionize cancer treatments, including the more recent development of immunotherapies. Immune cells are an important component of the tumor microenvironment that influence progression and treatment responses, particularly to the new immunotherapies. Technological advances that help to decipher the complexity and diversity of the tumor immune microenvironment (TIME) are increasingly used in translational research and biomarker studies. Current techniques that facilitate TIME evaluation include flow cytometry, multiplex bead-based immunoassays, chromogenic immunohistochemistry (IHC), fluorescent multiplex IHC, immunofluorescence, and spatial transcriptomics. This article offers an overview of our representative data, discusses the application of each approach to studies of the TIME, including their advantages and challenges, and reviews the potential clinical applications. Flow cytometry and chromogenic and fluorescent multiplex IHC were used to immune profile a HER2+ breast cancer, illustrating some points. Spatial transcriptomic analysis of a luminal B breast tumor demonstrated that important additional insight can be gained from this new technique. Finally, the development of a multiplex panel to identify proliferating B cells, Tfh, and Tfr cells on the same tissue section demonstrates their co-localization in tertiary lymphoid structures.

Neutrophil to apolipoprotein A-I ratio as an independent indicator of locally advanced nasopharyngeal carcinoma

PURPOSE

To explore the peripheral blood cells (neutrophil/monocyte/lymphocyte/platelet) to apolipoprotein AI or high-density lipoprotein-cholesterol ratio (NAR, MAR, LAR, PAR, NHR, MHR, LHR, and PHR) as independent prognostic indicators for stage III nasopharyngeal carcinoma (NPC).

PATIENTS AND METHODS

Between 2009 and 2014, 562 patients diagnosed with stage III NPC who were treated with a concomitant chemotherapy and intensity-modulated radiotherapy with cumulative cisplatin dose ≥200 mg/m2 were included in this retrospective study. Routine blood and biochemical variables and baseline clinical characteristics (T and N stage, age, sex, and induction chemotherapy) were collected. After inserting 19 hematological parameters into a set, we applied the least absolute shrinkage and selection operator (LASSO) algorithm and restricted cubic splines regression to select valuable parameters for predicting 5-year overall survival (OS). Subsequently, univariate and multivariate survival analyses were used to assess independent indicators of 5-year OS, distant metastasis survival, regional recurrence-free survival (RRFS), and disease-free survival.

RESULTS

NAR, MAR, serum lactated dehydrogenase (LDH), and Epstein-Barr virus (EBV)-DNA were selected using LASSO regression, and the optimal cut-off values for NAR, MAR, EBV-DNA, and, LDH were 4.39, 0.3, 1590 copies/mL, and 218.4 IU/L, respectively. In multivariate survival analysis, higher NAR was associated with both poor 5-year OS and RRFS (hazard ratio [HR], 1.88; 95% confidence interval [CI], 1.09-3.25, P = .024; HR, 3.13; 95% CI, 1.42-6.91, P = .005, respectively).

CONCLUSION

NAR could be an attractive indicator for evaluating the 5-year OS in patients with stage III NPC, which is closely related to inflammation and circulating lipid metabolism.Level of Evidence: 4.

Leveling Up the Controversial Role of Neutrophils in Cancer: When the Complexity Becomes Entangled

Neutrophils are the most abundant immune cell in the circulation of human and act as gatekeepers to discard foreign elements that have entered the body. They are essential in initiating immune responses for eliminating invaders, such as microorganisms and alien particles, as well as to act as immune surveyors of cancer cells, especially during the initial stages of carcinogenesis and for eliminating single metastatic cells in the circulation and in the premetastatic organs. Since neutrophils can secrete a whole range of factors stored in their many granules as well as produce reactive oxygen and nitrogen species upon stimulation, neutrophils may directly or indirectly affect carcinogenesis in both the positive and negative directions. An intricate crosstalk between tumor cells, neutrophils, other immune cells and stromal cells in the microenvironment modulates neutrophil function resulting in both anti- and pro-tumor activities. Both the anti-tumor and pro-tumor activities require chemoattraction towards the tumor cells, neutrophil activation and ROS production. Divergence is seen in other neutrophil properties, including differential secretory repertoire and membrane receptor display. Many of the direct effects of neutrophils on tumor growth and metastases are dependent on tight neutrophil–tumor cell interactions. Among them, the neutrophil Mac-1 interaction with tumor ICAM-1 and the neutrophil L-selectin interaction with tumor-cell sialomucins were found to be involved in the neutrophil-mediated capturing of circulating tumor cells resulting in increased metastatic seeding. On the other hand, the anti-tumor function of neutrophils was found to rely on the interaction between tumor-surface-expressed receptor for advanced glycation end products (RAGE) and Cathepsin G expressed on the neutrophil surface. Intriguingly, these two molecules are also involved in the promotion of tumor growth and metastases. RAGE is upregulated during early inflammation-induced carcinogenesis and was found to be important for sustaining tumor growth and homing at metastatic sites. Cathepsin G was found to be essential for neutrophil-supported lung colonization of cancer cells. These data level up the complexity of the dual role of neutrophils in cancer.

Current Understanding of the Neutrophil Transcriptome in Health and Disease

Neutrophils are key cells of the innate immune system. It is now understood that this leukocyte population is diverse in both the basal composition and functional plasticity. Underlying this plasticity is a post-translational framework for rapidly achieving early activation states, but also a transcriptional capacity that is becoming increasingly recognized by immunologists. Growing interest in the contribution of neutrophils to health and disease has resulted in more efforts to describe their transcriptional activity. Whilst initial efforts focused predominantly on understanding the existing biology, investigations with advanced methods such as single cell RNA sequencing to understand interactions of the entire immune system are revealing higher flexibility in neutrophil transcription than previously thought possible and multiple transition states. It is now apparent that neutrophils utilise many forms of RNA in the regulation of their function. This review collates current knowledge on the nuclei structure and gene expression activity of human neutrophils across homeostasis and disease, before highlighting knowledge gaps that are research priority areas.