The intracellular bacterium Fusobacterium nucleatum (Fn) mediates tumorigenesis and progression in colorectal cancer (CRC). However, the origin of intratumoral Fn and the role of Fn-infected immunocytes in the tumor microenvironment remain unclear. Here, we observed that Fn-infected neutrophils/macrophages (PMNs/MΦs), especially PMNs, accumulate in tumor tissues and fecal Fn abundance correlates positively with an abundance of blood PD-L1+ PMNs in CRC patients. Moreover, Fn accumulates in tumor tissues of tumor-bearing mice via intragingival infection and intravenous injection. Mechanistically, Fn can survive inside PMNs by reducing intracellular ROS levels and producing H2S. Specifically, the lysozyme inhibitor Fn1792 as a novel virulence factor of Fn suppressed apoptosis of phagocytes by inducing CX3CR1 expression. Furthermore, Fn-driven CX3CR1+PD-L1+ phagocytes transfer intracellular Fn to tumor cells, which recruit PMNs/MΦs through the CXCL2/8-CXCR2 and CCL5/CCR5 axes. Consequently, CX3CR1+PD-L1+ PMNs infiltration promotes CRC metastasis and weakens the efficacy of immunotherapy. Treatment with the doxycycline eradicated intracellular Fn, thereby reducing the CX3CR1+PD-L1+ PMNs populations and slowing Fn-promoted tumor growth and metastasis in mice. These results suggest phagocytes as Fn-presenting cells use mutualistic strategies to home to tumor tissues and induce immunosuppression, and treatment with ROS-enhanced antibiotics can inhibit Fn-positive tumor progression.

Targeted regulation of neutrophils is an effective approach for treating neutrophil-driven inflammatory diseases, but challenges remain in minimizing off-target effects and extending drug half-life. A DNA-based nanorobot was developed to target neutrophils by using an N-acetyl Pro-Gly-Pro (Ac-PGP) peptide to specifically bind to the C-X-C motif of chemokine receptor 2 (CXCR2) on neutrophil membranes. This robot (a tetrahedral framework nucleic acid modified with Ac-PGP, APT) identified and hitchhiked neutrophils to accumulate at inflammatory sites and prolong its half-lives, whilst also was internalized to influence the neutrophil cell cycle and maturation process to regulate oxidative stress, inflammation, migration, and recruitment in both in vivo and in vitro inflammation experiments. Consequently, the tissue damage caused by sepsis was greatly reduced. This novel neutrophil-based nanorobot highlights the high precision of targeting and regulating neutrophils, and presents a potential strategy for treating multiple neutrophil-driven diseases.

Radiotherapy, employing high-energy rays to precisely target and eradicate tumor cells, plays a pivotal role in the treatment of various malignancies. Despite its therapeutic potential, the effectiveness of radiotherapy is hindered by the tumor's inherent low radiosensitivity and the immunosuppressive microenvironment. Here we present an innovative approach that integrates peroxynitrite (ONOO-)-mediated radiosensitization with the tumor-associated neutrophils (TANs) polarization for the reversal of immunosuppressive tumor microenvironment (TME), greatly amplifying the potency of radiotherapy. Our design employs X-ray-activated lanthanide-doped scintillators (LNS) in tandem with photosensitive NO precursor to achieve in-situ ONOO- generation. Concurrently, the co-loaded TGF-β inhibitor SB525334, released from the LNS-RS nanoplatform in response to the overexpressed GSH in tumor site, promotes the reprogramming of TANs from N2 phenotype toward N1 phenotype, effectively transforming the tumor-promoting microenvironment into a tumor-inhibiting state. This 'one-two punch' therapy efficiently trigger a robust anti-tumor immune response and exert potent therapeutic effects in orthotopic colorectal cancer and melanoma mouse model. Meanwhile, it also significantly prevents liver metastasis and recurrence in metastatic colorectal cancer. The development of X-ray-controlled platforms capable of activating multiple therapeutic modalities may accelerate the clinical application of radiotherapy-based collaborative therapy.

Breast cancers (BCs) are frequently linked to an immunosuppressive microenvironment that facilitates tumor evasion of anti-cancer immunity. The cells that suppress the immune system such as regulatory B cells (Bregs), regulatory T cells (Tregs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), play a crucial role in immune resistance. Also, tumor progression and immune evasion of cancers are facilitated by cytokines and factors released by tumor cells or immunosuppressive cells. Targeting these regulatory cells therapeutically, whether through elimination, inactivation, or reprogramming, has resulted in hopeful anti-tumor reactions. Yet, the substantial diversity and adaptability of these cells, both in terms of appearance and function, as well as their variation over time and depending on where they are in the body, have posed significant challenges for using them as reliable biomarkers and creating focused therapies that could target their creation, growth, and various tumor-promoting roles. The immunotherapy approaches in BC and their effectiveness in treating certain subtypes are still in their initial phases. In this review, we thoroughly outlined the characteristics, roles, and possible treatment options for these immune-suppressing cells in the tumor environment.

Gastric cancer is a major oncological challenge, ranking highly among causes of cancer-related mortality worldwide. This study was initiated to address the variability in patient responses to combination chemotherapy, highlighting the need for personalized treatment strategies based on genomic data.

We analyzed whole-genome and RNA sequences from biopsy specimens of 65 advanced gastric cancer patients before their chemotherapy treatment. Using machine learning techniques, we developed a model with 123 omics features, such as immune signatures and copy number variations, to predict their chemotherapy outcomes.

The model demonstrated a prediction accuracy of 70-80% in forecasting chemotherapy responses in both test and validation cohorts. Notably, tumor-associated neutrophils emerged as significant predictors of treatment efficacy. Further single-cell analyses from cancer tissues revealed different neutrophil subgroups with potential antitumor activities suggesting their usefulness as biomarkers for treatment decisions.

This study confirms the utility of machine learning in advancing personalized medicine for gastric cancer by identifying tumor-associated neutrophils and their subgroups as key indicators of chemotherapy response. These findings could lead to more tailored and effective treatment plans for patients.

Neutrophils are pivotal in the immune system and have been recognized as significant contributors to cancer development and progression. These cells undergo metabolic reprogramming in response to various stimulus, including infections, diseases, and the tumor microenvironment (TME). Under normal conditions, neutrophils primarily rely on aerobic glucose metabolism for energy production. However, within the TME featured by hypoxic and nutrient-deprived conditions, they shift to altered anaerobic glycolysis, lipid metabolism, mitochondrial metabolism and amino acid metabolism to perform their immunosuppressive functions and facilitate tumor progression. Targeting neutrophils within the TME is a promising therapeutic approach. Yet, focusing on their metabolic pathways presents a novel strategy to enhance cancer immunotherapy. This review synthesizes the current understanding of neutrophil metabolic reprogramming in the TME, with an emphasis on the underlying molecular mechanisms and signaling pathways. Studying neutrophil metabolism in the TME poses challenges, such as their short lifespan and the metabolic complexity of the environment, necessitating the development of advanced research methodologies. This review also discusses emerging solutions to these challenges. In conclusion, given their integral role in the TME, targeting the metabolic pathways of neutrophils could offer a promising avenue for cancer therapy.

Hepatocellular carcinoma (HCC) is a significant global health issue, ranking as the sixth most prevalent malignancy and the fourth leading cause of cancer-related mortality worldwide. Despite advancements in therapeutic strategies, mortality rates for HCC remain high. The tumor immune microenvironment (TIME) plays a vital role in HCC progression by influencing tumor cell survival and growth. Recent studies highlight the essential role of exosomes in mediating intercellular communication within the TIME, particularly in interactions among tumor cells, immune cells, and fibroblasts. These interactions drive critical aspects of tumor development, including immune escape, angiogenesis, drug resistance, and metastasis. A detailed understanding of the molecular mechanisms by which exosomes modulate the TIME is essential for developing targeted therapies. This review systematically evaluated the roles and regulatory mechanisms of exosomes within the TIME of HCC, examining the impact of both HCC-derived and non-HCC-derived exosomes on various cellular components within the TIME. It emphasized their regulatory effects on cell phenotypes and functions, as well as their roles in HCC progression. The review also explored the potential applications of exosome-based immunotherapies, offering new insights into improving therapeutic strategies for HCC.

M6A modification is one of the most common regulatory mechanisms of gene expression in eukaryotic cells, influencing processes such as RNA splicing, degradation, stability, and protein translation. Studies have shown that m6A methylation is closely associated with tumorigenesis and progression, and it plays a key regulatory role in tumor immune responses. m6A modification participates in regulating the differentiation and maturation of immune cells, as well as related anti-tumor immune responses. In the tumor microenvironment, m6A modification can also affect immune cell recruitment, activation, and polarization, thereby promoting or inhibiting tumor cell proliferation and metastasis, and reshaping the tumor immune microenvironment. In recent years, immunotherapies for tumors, such as immune checkpoint inhibitors and adoptive cell immunotherapy, have been increasingly applied in clinical settings, achieving favorable outcomes. Targeting m6A modifications to modulate the immune system, such as using small-molecule inhibitors to target dysregulated m6A regulatory factors or inducing immune cell reprogramming, can enhance anti-tumor immune responses and strengthen immune cell recognition and cytotoxicity against tumor cells. m6A modification represents a new direction in tumor immunotherapy with promising clinical potential. This review discusses the regulatory role of m6A methylation on immune cells and tumor immune responses and explores new strategies for immunotherapy.

Cell fate changes play a crucial role in the processes of natural development, disease progression, and the efficacy of therapeutic interventions. The definition of the various types of cell fate changes, including cell expansion, differentiation, transdifferentiation, dedifferentiation, reprogramming, and state transitions, represents a complex and evolving field of research known as cell lineage tracing. This review will systematically introduce the research history and progress in this field, which can be broadly divided into two parts: prospective tracing and retrospective tracing. The initial section encompasses an array of methodologies pertaining to isotope labeling, transient fluorescent tracers, non-fluorescent transient tracers, non-fluorescent genetic markers, fluorescent protein, genetic marker delivery, genetic recombination, exogenous DNA barcodes, CRISPR-Cas9 mediated DNA barcodes, and base editor-mediated DNA barcodes. The second part of the review covers genetic mosaicism, genomic DNA alteration, TCR/BCR, DNA methylation, and mitochondrial DNA mutation. In the final section, we will address the principal challenges and prospective avenues of enquiry in the field of cell lineage tracing, with a particular focus on the sequencing techniques and mathematical models pertinent to single-cell genetic lineage tracing, and the value of pursuing a more comprehensive investigation at both the spatial and temporal levels in the study of cell lineage tracing.

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

Pancreatic cancer liver metastasis is an important factor leading to dismal prognoses. The details of adaptive immune remodeling in liver metastasis, especially the role of neutrophils, remain elusive. Here, combined single-cell sequencing with spatial transcriptomics results revealed that liver metastases exhibit more aggressive transcriptional characteristics and higher levels of immunosuppression compared with the primary tumor. We identified neutrophils_S100A12 (S100 calcium binding protein A12) cells as the pivotal pro-metastatic cluster, specifically distributed at the invasive front of the metastatic lesions. Mechanistically, our findings indicated that nuclear factor erythroid 2 (NFE2) is a key transcription factor regulating neutrophil phenotypic polarization. Metastatic tumors produce transforming growth factor β to activate the SMAD3 pathway within neutrophils, inducing NFE2-driven polarization. NFE2 promotes the transcription of peptidylarginine deiminase 4 by binding to its promoter, leading to the generation of neutrophil extracellular traps at the invasive front. Collectively, our data demonstrate that NFE2-driven neutrophil polarization is a potential target for anti-metastatic therapy.

Colorectal cancer (CRC) exhibits significant molecular and immunological heterogeneity. Neutrophil infiltration patterns play a crucial yet poorly understood role in tumor progression and patient outcomes. This study presents a comprehensive single-cell atlas of the CRC tumor microenvironment (TME), integrating transcriptomic data from 388,511 cells across 98 samples from 63 patients. Employing advanced computational methods, we stratified patients based on their immune cell infiltration profiles, revealing distinct immunophenotypes with potential therapeutic implications. Our analysis focused on tissue-resident neutrophils (TRNs) and uncovered previously uncharacterized subpopulations with diverse functional states. Trajectory inference analysis revealed a dynamic differentiation path from normal-associated neutrophils to tumor-associated neutrophils, highlighting the remarkable plasticity of these cells within the tumor environment. By integrating single-cell data with bulk transcriptomic and clinical information, we identified specific neutrophil-derived gene signatures associated with poor prognosis in CRC, suggesting their potential as novel prognostic biomarkers. This study not only provides unprecedented insights into neutrophil heterogeneity in CRC but also identifies potential targets for immunomodulatory therapies. Our findings lay the groundwork for developing more nuanced, personalized immunotherapeutic strategies for CRC, potentially improving treatment efficacy for patients who currently show a limited response to existing immunotherapies.

Advancing the understanding of the various roles and components of the immune system requires sophisticated methods and technology for the detection of immune cells in their natural states. Recent advancements in the development of molecular probes for optical imaging have paved the way for non-invasive visualization and real-time monitoring of immune responses and functions. Here we discuss recent progress in the development of molecular probes for the selective imaging of specific immune cells. We emphasize the design principles of the probes and their comparative performance when using various optical modalities across disease contexts. We highlight molecular probes for imaging tumour-infiltrating immune cells, and their applications in drug screening and in the prediction of therapeutic outcomes of cancer immunotherapies. We also discuss the use of these probes in visualizing immune cells in atherosclerosis, lung inflammation, allograft rejection and other immune-related conditions, and the translational opportunities and challenges of using optical molecular probes for further understanding of the immune system and disease diagnosis and prognosis.

Abnormal metabolism of melanoma cells on lipids reveals that breaking their lipid addiction provides a starvation strategy to enhance immunotherapy effects and reduce resistance. Herein, we propose an extracellular matrix-inspired scaffold fabricated by multiple cross-linking of collagen and elastin encapsulated with fatty acid transporter proteins (FATP) inhibitor lipofermata (Lipo) to close the "valve" of lipid transported into both melanoma cells and pro-tumor neutrophils. Meanwhile, model TGF-β inhibitor loaded in scaffold synergized with Lipo to polarize postoperative locally enriched neutrophils towards cytotoxic N1 phenotypes after blocking their energy supply and modulate postsurgical immunosuppressive tumor microenvironment. These N1 neutrophils induced tumor pyroptosis through a reactive oxygen species (ROS)-dependent pathway under melanoma cells suffered starvation, and the intracellular contents released from dead melanoma cells stimulated macrophages into producing proinflammatory cytokines, which recruited a secondary wave of neutrophils to the tumor site. Benefiting from the N1 neutrophil induced tumor pyroptosis feedback loop in situ, adaptive and memory antitumor immunity is activated for suppressing aggressive melanoma recurrence and metastasis. Altogether, this lipid starvation strategy synergized with neutrophil activation for amplification of tumor-specific immunotherapy provides a new paradigm for pyroptosis-mediated postsurgical melanoma therapy.

Tumor-associated neutrophils (TANs) actively interact with antibody-drug conjugates (ADCs) within the tumor microenvironment (TME), though the detailed mechanisms governing their response to ADC treatment remain to be fully elucidated. Herein, we explored how ICAM1-targeted ADCs affect TAN dynamics in preclinical models of cervical cancer. We discovered that I-DXd, our in-house ADC targeting cervical cancer, effectively eliminates tumor cells through specific antigen recognition while concurrently depleting pro-tumor VEGFA + TANs via Fcγ receptor-mediated phagocytosis. This dual action promotes an immunologically favorable TME. Through comprehensive preclinical studies, we established a foundational understanding of the synergistic benefits of combining I-DXd treatment with PD-1 immune checkpoint inhibition, thereby opening new avenues for therapeutic intervention in advanced cervical cancer.

Peritoneal metastasis (PM) is common in colorectal cancer (CRC), yet its underlying mechanisms are poorly understood. Here, we explored the transcriptional profile of CRC, PM and adjacent tissues revealing key players that facilitate PM. Single-cell analysis of 48 matched samples from 12 patients revealed that remodeling of malignant cells and the tumor microenvironment promotes CRC progression and metastasis. Multiplexed imaging confirmed depletion in PM by enrichment in CRC tissues of neutrophils associated with mucosal immunity disruption, intestinal microbiota dysbiosis and mesenchymal transition of both cancerous and mesothelial cells. Functional analyses in cell lines, organoids and in vivo models demonstrated that dysbiosis promoted inflammation and protumor neutrophil recruitment, while coupled mesenchymal transition of malignant and mesothelial cells disrupted the stromal structure and increased cancer cell invasiveness. Our findings suggest that targeting mesothelial cells and tumor microenvironment remodeling may offer therapeutic strategies for CRC-PM.

Esophageal cancer (EC) is associated with a high morbidity and mortality rate. Immunotherapy has demonstrated effective antitumor activity in patients with EC, making it imperative to investigate easily accessible prognostic factors. Consequently, we conducted a meta-analysis to explore the prognostic significance of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in EC patients treated with immunotherapy.

The literature search was conducted across three databases: PubMed, Embase, and Web of Science. The primary deadline for literature retrieval was July 2024. Hazard ratio (HR) with a 95% confidence interval (CI) was utilized to assess the association between NLR or PLR and overall survival (OS) as well as progression-free survival (PFS). Statistical analysis was performed using Review Manager version 5.4 and STATA version 15.0.

The meta-analysis included a total of 16 studies involving 1,481 patients. The results indicated a significant correlation between high pretreatment NLR and poor PFS (HR=1.76, 95%CI:1.38-2.25, p<0.001) as well as poor OS (HR=2.61,95%CI:1.86-3.67, p<0.001). Subgroup analyses based on tumor stage revealed that the association between elevated NLR and poor PFS was only observed in advanced EC patients. Regarding PLR, an increased PLR was found to be indicative of inferior PFS (HR=1.44, 95%CI: 1.20-1.72, p<0.001) and OS (HR=1.72,95%CI:1.08-2.74, p=0.020). However, the sensitivity analyses suggested that the observed increase in PLR lack robustness in terms of its impact on inferior OS.

Elevated NLR and PLR are associated with inferior PFS and OS in EC patients receiving immunotherapy. These findings suggest that NLR and PLR levels hold promise as prognostic biomarkers in clinical practice, offering valuable guidance for personalized immunotherapy strategies.

PROSPERO https://www.crd.york.ac.uk/prospero/, identifier CRD42024596737.

Neutrophils in the tumor microenvironment (TME) are heterogeneous populations associated with cancer prognosis and immunotherapy. However, the plasticity and function of heterogeneous neutrophils in the TME of non-small-cell lung cancer (NSCLC) remain unclear. Here, we show that neutrophils produce high levels of interleukin (IL)-8, which induce the differentiation of CD74highSiglecFlow neutrophils and suppress the generation of CD74lowSiglecFhigh neutrophils in the TME of IL-8-humanized NSCLC mice. The CD74highSiglecFlow neutrophils boost anti-tumor T cell responses via antigen cross-presentation. Deleting CD74 in IL-8-humanized neutrophils impairs T cell activation and exacerbates NSCLC progression, whereas a CD74 agonist enhances T cell activation and the efficacy of anti-programmed cell death 1 (PD-1) or osimertinib therapies. Additionally, the CD74highCD63low neutrophils in the TME and peripheral blood of advanced NSCLC patients phenocopy the CD74highSiglecFlow neutrophils in the TME of NSCLC mice and correlate well with the responsiveness to anti-PD-1 plus chemotherapies. These findings demonstrate an IL-8-CD74high neutrophil axis that promotes anti-tumor immunity in NSCLC.

Design and development of efficient drug delivery technologies that impart site-specificity is the need of the hour for the effective treatment of lung cancer. The emergence of materials science and nanotechnology partially helped drug delivery scientists to achieve this objective. Various stimuli-responsive materials that undergo degradation at the pathological tumor microenvironment (TME) have been developed and explored for drug delivery applications using nanotechnological approaches. Nanoparticles (NPs), owing to their small size and high surface area to volume ratio, demonstrated enhanced cellular internalization, permeation, and retention at the tumor site. Such passive accumulation of stimuli-responsive materials helped to achieve spatiotemporally controlled and targeted drug delivery within the tumors. In this review, we discussed various stimuli-physical (interstitial pressure, temperature, and stiffness), chemical (pH, hypoxia, oxidative stress, and redox state), and biological (receptor expression, efflux transporters, immune cells, and their receptors or ligands)-that are characteristic to the TME. We mentioned an array of biomaterials-based nanoparticulate delivery systems that respond to these stimuli and control drug release at the TME. Further, we discussed nanoparticle-based combinatorial drug delivery strategies. Finally, we presented our perspectives on challenges related to scale-up, clinical translation, and regulatory approvals.

Circulating tumor cells (CTCs) travel through the vasculature to seed secondary sites and serve as direct precursors of metastatic outgrowth for many solid tumors. Heterotypic cell clusters form between CTCs and white blood cells (WBCs) and recent studies report that a majority of these WBCs are neutrophils in patient and mouse models. The lab discovered that CTCs produce tubulin-based protrusions, microtentacles (McTNs), which promote reattachment, retention in distant sites during metastasis and formation of tumor cell clusters. Neutrophil-CTC clusters help CTCs survive the harsh vascular environment to promote successful metastasis, however, the specific mechanism of this interaction is not fully understood. Utilizing TetherChip technology, it is found that primary and differentiated neutrophils produce McTNs composed of detyrosinated and acetylated α-tubulin and vimentin. Neutrophil McTNs aid in cluster formation, migration, and reattachment, which are suppressed with the tubulin-depolymerizing agent, Vinorelbine. Co-culturing differentiated neutrophils and tumor cells formed heterotypic clusters that enhanced migration. CTC-neutrophil clusters have higher metastatic efficiency, and by demonstrating that neutrophils form McTNs, a new possible mechanism for how neutrophils interact with tumor cells is revealed. These findings further support the idea that developing cluster-disrupting therapies can provide a new targeted strategy to reduce the metastatic potential of cancer cells.

Cardiovascular disease and cancer are the leading causes of death in the Western world. The associated risk factors are increased by smoking, hypertension, diabetes, sedentary lifestyle, aging, unbalanced diet, and alcohol consumption. Therefore, the study of cellular metabolism has become of increasing importance, with current research focusing on the alterations and adjustments of the metabolism of cancer patients. This may also affect the efficacy and tolerability of anti-cancer therapies such as immune-checkpoint inhibition (ICI). This review will focus on metabolic adaptations and their consequences for various cell types, including cancer cells, cardiac myocytes, and immune cells. Focusing on ICI, we illustrate how anti-cancer therapies interact with metabolism. In addition to the desired tumor response, we highlight that ICI can also lead to a variety of side effects that may impact metabolism or vice versa. With regard to the cardiovascular system, ICI-induced cardiotoxicity is increasingly recognized as one of the most life-threatening adverse events with a mortality of up to 50%. As such, significant efforts are being made to assess the specific interactions and associated metabolic changes associated with ICIs to improve both efficacy and management of side effects.

Gastric adenocarcinoma (GAC), particularly the Lauren intestinal-type GAC (IGAC), leads to significant mortality in China due to the limited effectiveness of current treatments. This study aims to investigate the mechanisms of immune suppression in IGAC to identify potential targets for enhancing immunotherapy outcomes.

Performing an extensive collection and re-analysis of single-cell RNA sequencing (scRNA-seq) of tumor tissues and the corresponding noncancerous mucosae from 15 Chinese patients diagnosed with IGAC, we identified cell subpopulations involved in immune suppression within the tumor microenvironment (TME). We further validated our findings using spatially resolved transcriptomics (SRT), immunofluorescence (IF), and flow cytometry (FCM) on tissues from IGAC patients.

We demonstrated that the TME of IGAC harbors CD8+ exhausted T cells (Texs) and various subtypes that mediate immunity. We identified specific subpopulations of Texs (HAVCR2+VCAM1+) and regulatory T cells (Tregs) (LAYN+TNFRSF4+) contributing to immune suppression. Furthermore, TNFRSF12A+ cancer-associated fibroblasts (CAFs), CTSB+ macrophages, and SOD2+ monocytes were found to be involved in maintaining the immunosuppressive milieu. SRT and IF assays confirmed the presence and colocalization of these cell types within the tumor tissues, highlighting their functional interactions. FCM assays indicated that the prevalence of HAVCR2+VCAM1+ Texs and LAYN+TNFRSF4+ Tregs in tumor tissues was positively associated with IGAC progression.

Detailed profiles of immunosuppressive cell subpopulations in IGAC provide valuable insights into the complexity and heterogeneity of immunosuppression. These findings underscore the necessity for targeted strategies that disrupt specific immunosuppressive pathways, potentially enhancing the efficacy of immunotherapeutic interventions in IGAC.

Activation of neutrophils has proven to be useful in different models of cancer therapy. However, more comprehensive studies are required to further characterize these potential targets. Thus, we aimed to evaluate the effects of programmed cell death protein-1 (PD-1) and toll-like receptor 9 (TLR-9) inhibition on markers of neutrophil activation in different breast cancer subtypes.

Neutrophils were cultured and treated with PD-1 and TLR-9 inhibitors after being isolated from 43 triple negative breast cancer (TNBC), 31 non-TNBC patients and 30 healthy females. Enzyme linked immunosorbent assay (ELISA) was then used to detect neutrophil elastase (NE) and myeloperoxidase (MPO) in culture supernatants.

The results revealed that increased NE and MPO were significantly associated with advanced clinical stage and vascular invasion, respectively. In addition, treatment with either anti-PD-1 or anti-TLR-9 was associated with a significant decrease in NE and MPO levels of both TNBC and non-TNBC samples compared to untreated samples. Moreover, the ameliorative effect of both treatments was observed to be more obvious on MPO levels compared to NE levels in breast cancer subtypes.

These results may highlight the possible therapeutic role of PD-1 and TLR-9 inhibitors in modulating neutrophil activation markers (NE and MPO) in breast cancer subtypes.

Sepsis-induced immunosuppression is related to increased susceptibility to secondary infections and death. Lung is the most vulnerable target organ in sepsis, but the understanding of the pulmonary immunosuppression state is still limited. Here, single-cell RNA sequencing of bronchoalveolar lavage fluid (BALF) is performed to map the landscape of immune cells, revealing a neutrophil-driven immunosuppressive program in the lungs of patients with immunosuppressive sepsis. Although immunosuppressive genes are upregulated in different immune cells, only neutrophils dramatically increase in the BALF of patients in immunosuppressive phase of sepsis. Five neutrophil subpopulations in BALF are identified, among which CXCR2+ and CD274 (PD-L1 coding gene)+IL1RN+ neutrophil subpopulations increased significantly during septic immunosuppression. Interestingly, a developmental trajectory from CXCR2+ to CD274+IL1RN+ neutrophil subpopulation is disclosed. Moreover, the therapeutic effect of CXCR2 blockade is observed on the survival of septic mice, along with a decreased number of PD-L1+ neutrophils. Taken together, the CXCR2+ neutrophil subpopulation is discovered as a contributor to immunosuppression in sepsis and identified it as a potential therapeutic target in sepsis treatment.

Ulcerative colitis (UC) is an inflammatory colon and rectum disease affecting approximately 5 million people worldwide. There is no cure available for UC, and approximately 8% of patients with UC develop colorectal cancer (CRC) by gradual acquisition of mutations driving the formation of adenomas and their progression to adenocarcinomas and metastatic disease. CRC constitutes 10% of total cancer cases worldwide and 9% of cancer deaths. Both UC and CRC have an increasing incidence worldwide. Although the epithelium has been well studied in UC and CRC, the contributions of neutrophils are less clear. They are rapidly recruited in excessive amounts from peripheral blood to the colon during UC, and their overactivation in the proinflammatory UC tissue environment contributes to tissue damage. In CRC, the role of neutrophils is controversial, but emerging evidence suggests that their role depends on the evolution and context of the disease. The role of neutrophils in the transition from UC to CRC is even less clear. However, recent studies propose neutrophils as therapeutic targets for better clinical management of both diseases. This review summarizes the current knowledge on the roles of neutrophils in UC and CRC.

Neutrophils, the most abundant circulating white blood cells, are essential for the initial immune response to infection and injury. Emerging research reveals a dualistic function of neutrophils in cancer, where they can promote or inhibit tumor progression. This dichotomy is influenced by the tumor microenvironment, with neutrophils capable of remodeling the extracellular matrix, promoting angiogenesis, or alternatively inducing cancer cell death and enhancing immune responses. An intriguing yet poorly understood aspect of neutrophil-cancer interactions is the phenomenon of neutrophil engulfment by cancer cells, which has been observed across various cancers. This process, potentially mediated by LC3-associated phagocytosis (LAP), raises questions about whether it serves as a mechanism for immune evasion or contributes to tumor cell death through pathways like ferroptosis. This review examines current knowledge on neutrophil development, their roles in cancer, and the mechanisms of LAP in neutrophil engulfment by tumor cells. We discuss how manipulating LAP impacts cancer progression and may represent a therapeutic strategy. We also explore neutrophils' potential as delivery vehicles for cancer therapeutic agents. Understanding the complex functions of tumor-associated neutrophils (TANs) and the molecular mechanisms underlying LAP in cancer may open new avenues for effective therapeutic interventions and mitigate potential risks.

The present immune therapy was focused on the immune checkpoint blockade or Chimeric Antigen Receptor T-Cell Immunotherapy (CART) transfer, but how to activate the innate immune system to antitumor still lags out. Neutrophils are the most abundant circulating leukocytes in human, and heterogeneous neutrophils have been increasingly recognized as important players in tumor progression. They play double "edge-sward" by either supporting or suppressing the tumor growth, including driving angiogenesis, extracellular matrix remodeling to promote tumor growth, participating in antitumor adaptive immunity, or killing tumor cells directly to inhibit the tumor growth. The complex role of neutrophils in various tumors depends on the tumor microenvironment (TME) they are located, and emerging evidence has suggested that neutrophils may determine the success of tumor immunotherapy in the context of the immune checkpoint blockade, innate immune training, or drug-loaded extracellular microvesicles therapy, which makes them become an exciting target for tumor immunotherapy, but still with challenges. Here, we summarize the latest insights on how to activate neutrophils in antitumor immunity and discuss the advances of neutrophil-targeted immunotherapy strategies.

Cancer disrupts intratumoral innate-adaptive immune crosstalk, but how the systemic immune landscape evolves during breast cancer progression remains unclear. We profiled circulating immune cells in stage I-III and stage IV triple-negative breast cancer (TNBC) patients and healthy donors (HDs). Metastatic TNBC (mTNBC) patients had reduced T cells, dendritic cells, and differentiated B cells compared to non-metastatic TNBC patients and HDs, partly linked to prior chemotherapy. Vδ1 γδ T cells from mTNBC patients produced more IL17 than those from HDs. Chemotherapy-naïve mTNBC patients showed increased classical monocytes and neutrophils. Transcriptional, proteomic, and functional analyses revealed that neutrophils in mTNBC exhibited enhanced migratory capacity, elevated granule proteins, and higher ROS production. Some immune changes, such as reduced non-switched B cells and heightened neutrophil migration, were evident in earlier TNBC stages. This study comprehensively maps systemic immunity in TNBC, guiding future research on patient stratification and immunomodulation strategies.

Black phosphorus (BP) has demonstrated potential as a drug carrier and photothermal agent in cancer therapy; however, its intrinsic functions in cancer treatment remain underexplored. This study investigates the immunomodulatory effects of polyethylene glycol-functionalized BP (BP-PEG) nanosheets in breast cancer models. Using immunocompetent mouse models-including 4T1 orthotopic BALB/c mice and MMTV-PyMT transgenic mice, it is found that BP-PEG significantly inhibits tumor growth and metastasis without directly inducing cytotoxicity in tumor cells. Mass cytometry analysis reveals that BP-PEG reshapes the tumor immune microenvironment by recruiting neutrophils. Neutrophil depletion experiments further demonstrate that the antitumor effects of BP-PEG are dependent on neutrophils. Moreover, bulk and single-cell RNA sequencing indicate that BP-PEG is mainly taken up by macrophages, leading to the release of inflammatory factors such as IL1A and CXCL2, which enhance neutrophil recruitment and activation, thereby amplifying the antitumor immune response. Finally, co-culture assays confirm that BP-PEG indeed enhances the antitumor activity of neutrophils and natural killer (NK) cells. These findings position BP-PEG as an immunomodulatory agent capable of reprogramming the tumor microenvironment to promote innate immunity against breast cancer. By stimulating neutrophil-mediated antitumor activity, BP-PEG offers a unique therapeutic approach that can potentially enhance the efficacy of existing cancer immunotherapies.

Inflammatory bowel disease (IBD) is a non-specific inflammatory disease of digestive tract, primarily manifesting as ulcerative colitis (UC) and Crohn's disease (CD). The precise etiology of IBD remains elusive. The interplay of genetic factors, environmental influences, and intestinal microbiota contributes to the establishment of an uncontrolled immune environment within the intestine, which can progressively lead to atypical hyperplasia and ultimately to malignancy over a long period. This colorectal malignant tumor that arises from chronic IBD is referred to as colitis-associated colorectal cancer (CAC). Dysregulation in the quantity and functionality of neutrophils plays a significant role in the onset, progression, and recurrence of IBD, as well as in the transition from IBD to CAC. Neutrophils affect the pathophysiology of IBD through various mechanisms, including the production of reactive oxygen species (ROS), degranulation, the release of inflammatory mediators and chemokines, and the formation of neutrophil extracellular traps (NETs). These processes can induce DNA mutations, thereby facilitating the development of colon cancer. Given the incomplete understanding of the disease mechanisms underlying IBD and CAC, effective treatment and prevention strategies remain challenging. Consequently, a comprehensive review of the functional roles of neutrophils in IBD and CAC is essential for advancing our understanding of IBD pathogenesis and identifying potential therapeutic targets.

Blood inflammation index has been shown to correlate with the prognosis of patients with gastric cancer. However, few studies have compared the efficacy of existing blood inflammatory markers in predicting the prognosis of patients with locally advanced gastric cancer in combination with neoadjuvant chemotherapy and immunotherapy.

The objective of this study was to compare the prognostic value of existing commonly used blood inflammatory index in patients with advanced gastric cancer treated with neoadjuvant chemotherapy combined with immunotherapy.

The clinicopathological data of patients with advanced gastric cancer from three centers in China were analyzed retrospectively. Univariate COX regression analysis was used to analyze the independent risk factors of poor tumor regression and overall survival (OS) in this part of patients, and the predictive value of different inflammatory indexes on prognosis was compared by C-index index. Finally, Inflammatory burden index(IBI) was grouped by X-tile software, and Kaplan-Meier method was used to compare the survival difference between groups.

A total of 163 patients were enrolled in this study. The median age was 63 years(56-68). The median cycle of neoadjuvant therapy was 4(3-4). The median survival time was 85.1%(1 years), 65.6%(2 years), and 47.4%(3 years).Univariate analysis showed that IBI was an independent risk factor for non-TR(residual tumor cells>50%) (HR=1.08,95%CI:1.00-1.45,p<0.001)and OS(HR=1.04,95%CI:1.03-1.05,p<0.001). IBI is the best predictor of OS (C-index: 0.82, 95% CI: 0.78-0.87) among all inflammatory indexes. The IBI cutoff value was 52.1. It was found that the high IBI group had a higher incidence of postoperative complications(32.1%vs14.3%, p=0.001), the proportion of non-TR patients was significantly higher than that of the low IBI group(64.3%vs35.7%, p =0.001), and the high IBI group had a significantly lower OS((47.6% vs 87.6%, p < 0.001).

IBI is the best inflammatory index to predict the prognosis of advanced gastric cancer treated with neoadjuvant chemotherapy combined with immunotherapy, which will help guide patients' treatment decisions. This result still needs to be verified by large prospective studies.

There is a renewed interest in neutrophil biology, largely instigated by their prominence in cancer. From an immunologist's perspective, a conceptual breakthrough is the realization that prototypical inflammatory, cytotoxic leukocytes can be tamed to promote the survival and growth of other cells. This has sparked interest in defining the biological principles and molecular mechanisms driving the adaptation of neutrophils to cancer. Yet, many questions remain: is this adaptation mediated by reprogramming mature neutrophils inside the tumoral mass, or rather by rewiring granulopoiesis in the bone marrow? Why, in some instances, are neutrophils beneficial and in others detrimental to cancer? How many different functional programs can be induced in neutrophils by tumors, and is this dependent on the type of tumor? This review summarizes what we know about these questions and discusses therapeutic strategies based on our incipient knowledge of how neutrophils adapt to cancer.

Colorectal cancer (CRC) remains a significant cause of cancer-related mortality worldwide. Despite advancements in surgery, chemotherapy, and radiotherapy, the effectiveness of these conventional treatments is limited, particularly in advanced cases. Therefore, transition to novel treatment is urgently needed. Immunotherapy, especially immune checkpoint inhibitors (ICIs), has shown promise in improving outcomes for CRC patients. Notably, patients with deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H) tumors often benefit from ICIs, while the majority of CRC cases, which exhibit proficient mismatch repair (pMMR) or microsatellite-stable (MSS) status, generally show resistance to this approach. It is assumed that the MSI phenotype cause some changes in the tumor microenvironment (TME), thus triggering antitumor immunity and leading to response to immunotherapy. Understanding these differences in the TME relative to MSI status is essential for developing more effective therapeutic strategies. This review provides an overview of the TME components in CRC and explores current approaches aimed at enhancing ICI efficacy in MSS CRC.

Ewing's sarcoma (EwS), a common pediatric bone cancer, is associated with poor survival due to a lack of therapeutic targets for immunotherapy or targeted therapy. Therefore, more effective treatment options are urgently needed.

Since novel immunotherapies may address this need, we performed an integrative analysis involving single-cell RNA sequencing, cell function experiments, and humanized models to dissect the immunoregulatory interactions in EwS and identify strategies for optimizing immunotherapeutic efficacy.

EwS is infiltrated by immunosuppressive myeloid populations, T and B lymphocytes, and natural killer cells. We found that SLC40A1 and C1QA macrophages were associated with a poor prognosis, whereas CD8+ T-cell infiltration was associated with a good prognosis. A comparative analysis of paired samples revealed that in tumors with a good chemotherapeutic response, macrophages presented increased antigen presentation and reduced release of protumor cytokines, whereas CD8+ T cells presented increased cytotoxicity and reduced exhaustion. An interaction analysis revealed a vast immunoregulatory network and identified MIF-CD74 as a crucial immunoregulatory target that can simultaneously promote M2 polarization of macrophages and inhibit CD8+ T-cell infiltration. Importantly, MIF blockade effectively reshaped the tumor immune microenvironment, turning cold tumors hot and inhibiting tumor growth.

Our integrative analysis revealed that the MIF/CD74 axis is a promising target for the treatment of Ewing sarcoma and provides a rationale for this novel immunotherapy.

Tertiary lymphoid structures (TLSs) are organized ectopic lymphoid aggregates within the tumor microenvironment that serve as crucial sites for the development of adaptive antitumor cellular and humoral immunity. TLSs have been consistently documented in numerous cancer types, correlating with improved prognosis and enhanced responses to immunotherapy, especially immune-checkpoint blockade (ICB). Given the potential role of TLSs as predictive biomarkers for the efficacy of ICB in cancer patients, the therapeutic manipulation of TLSs is gaining significant attention as a promising avenue for cancer treatment. Herein, we comprehensively review the composition, definition, and detection methods of TLSs in humans. We also discuss the contributions of TLSs to antitumor immunity, their prognostic value in cancer patients, and their association with therapeutic response to ICB-based immunotherapy. Finally, we present preclinical data supporting the potential of therapeutically manipulating TLSs as a promising approach for innovative cancer immunotherapy.

Myeloid cells accumulate extensively in most tumors and play a critical role in immunosuppression of the tumor microenvironment (TME). Like T cells, myeloid cells also express immune checkpoint molecules, which induce the immunosuppressive phenotype of these cells. In this review, we summarize the tumor-promoting function and immune checkpoint expression of four types of myeloid cells: macrophages, neutrophils, dendritic cells, and myeloid-derived suppressor cells, which are the main components of the TME. By summarizing the research status of myeloid checkpoints, we propose that blocking immune checkpoints on myeloid cells might be an effective strategy to reverse the immunosuppressive status of the TME. Moreover, combining nanotechnology, cellular therapy, and bispecific antibodies to achieve precise targeting of myeloid immune checkpoints can help to avoid the adverse effects of systemic administration, ultimately achieving a balance between efficacy and safety in cancer therapy.

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

Neutrophils are the most abundant cell type in human blood and play a crucial role in the immune system and development of tumors. This review begins with the generation and development of neutrophils, traces their release from the bone marrow into the bloodstream, and finally discusses their role in the hepatocellular carcinoma (HCC) microenvironment. It elaborates in detail the mechanisms by which tumor-associated neutrophils (TANs) exert antitumor or protumor effects under the influence of various mediators in the tumor microenvironment. Neutrophils can exert antitumor effects through direct cytotoxic action. However, they can also accelerate the formation and progression of HCC by being recruited and infiltrated, promoting tumor angiogenesis, and maintaining an immunosuppressive microenvironment. Therefore, based on the heterogeneity and plasticity of neutrophils in tumor development, this review summarizes the current immunotherapies targeting TANs, discusses potential opportunities and challenges, and provides new insights into exploring more promising strategies for treating HCC.

Tumor vaccines, as an immunotherapeutic approach, harness the body's immune cells to provoke antitumor responses, which have shown promising efficacy in clinical settings. However, the immunosuppressive tumor microenvironment (TME) and the ineffective vaccine delivery systems hinder the progression of many vaccines beyond phase II trials. This article begins with a comprehensive review of the complex interactions between tumor vaccines and TME, summarizing the current state of vaccine clinical research. Subsequently, we review recent advancements in targeted vaccine delivery systems and explore biomaterial-based tumor vaccines as a strategy to improve the efficacy of both delivery systems and treatment. Finally, we have presented our perspectives on tumor vaccine development, aiming to advance the field towards the creation of more effective tumor vaccines.