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

Postoperative leukopenia after cytoreductive surgery and hypertherm intraperitoneal chemotherapy for colorectal carcinomatosis- causes and implication on outcomes in a population-based study

BACKGROUND

Leukocytes have been reported to have tumor stimulating effects in colorectal cancer, among other malignancies. In line with this, earlier research has shown improved disease-free survival in patients with postoperative neutropenia compared to non-neutropenic patients following cytoreductive surgery (CRS) and hypertherm intraperitoneal chemotherapy (HIPEC).

AIM

To evaluate the impact of postoperative leukopenia after CRS and HIPEC on recurrence rate, survival, and risk of complications.

METHODS

All CRS and HIPEC-procedures for colorectal adenocarcinoma in the national Swedish HIPEC-registry since 2015 and local registries in Uppsala and Malmö since 2003 until December 31st, 2021, were included (n = 921). Patients who did not complete a full CRS and HIPEC procedure (n = 99), had incomplete macroscopic cytoreduction (n = 25) or a lack of information on leukocyte count (n = 213) were excluded, resulting in 584 analyzed cases. Primary outcome was overall recurrence rate. Secondary outcomes were overall survival, recurrence-free survival, and perioperative complications.

RESULTS

Postoperative leukopenia was observed in 54 (9.2%) cases of which 32 (5.5%) developed severe leukopenia. No differences in patient characteristics were noted between those with or without leukopenia. There were no differences in 3-year recurrence rate, overall survival or 3-year recurrence-free survival, between the groups. Neoadjuvant chemotherapy treatment, HR 1.32 (95% CI: 1.02-1.71), higher PCI-score, HR 1.50 (95% CI: 1.09-2.05) and higher pN-stage HR 2.52 (95% CI: 1.74-3.65) were associated with higher 3-year recurrence rate. 3-year mortality was associated with neoadjuvant chemotherapy treatment, HR 1.82 (95% CI: 1.06-3.11), severe postoperative complication, HR 2.39 (95% CI: 1.39-4.13) and high PCI-score, HR 2.60 (95% CI: 1.31-5.14). Treatment with combined oxaliplatin/irinotecan, HR 12.34 (95% CI: 4.51-33.74) was associated with developing postoperative leukopenia. Longer operation time, HR 2.30 (95% CI: 1.55-3.42), and severe leukopenia, HR 3.50 (95% CI: 1.25-9.77) were associated with postoperative complication.

CONCLUSIONS

Postoperative leukopenia did not impact recurrence rate or long-term survival in a statistically significant manner. Neoadjuvant chemotherapy and high PCI-score were associated with both recurrent disease and mortality within 3 years.

Mitochondrial DNA signals driving immune responses: Why, How, Where?

There has been a recent expansion in our understanding of DNA-sensing mechanisms. Mitochondrial dysfunction, oxidative and proteostatic stresses, instability and impaired disposal of nucleoids cause the release of mitochondrial DNA (mtDNA) from the mitochondria in several human diseases, as well as in cell culture and animal models. Mitochondrial DNA mislocalized to the cytosol and/or the extracellular compartments can trigger innate immune and inflammation responses by binding DNA-sensing receptors (DSRs). Here, we define the features that make mtDNA highly immunogenic and the mechanisms of its release from the mitochondria into the cytosol and the extracellular compartments. We describe the major DSRs that bind mtDNA such as cyclic guanosine-monophosphate-adenosine-monophosphate synthase (cGAS), Z-DNA-binding protein 1 (ZBP1), NOD-, LRR-, and PYD- domain-containing protein 3 receptor (NLRP3), absent in melanoma 2 (AIM2) and toll-like receptor 9 (TLR9), and their downstream signaling cascades. We summarize the key findings, novelties, and gaps of mislocalized mtDNA as a driving signal of immune responses in vascular, metabolic, kidney, lung, and neurodegenerative diseases, as well as viral and bacterial infections. Finally, we define common strategies to induce or inhibit mtDNA release and propose challenges to advance the field.

Fucoidan reduces NET accumulation and alleviates chemotherapy-induced peripheral neuropathy via the gut-blood-DRG axis

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is a serious adverse reaction to chemotherapy with limited treatment options. Research has indicated that neutrophil extracellular traps (NETs) are critical for the pathogenesis of CIPN. LPS/HMGB1 serve as important inducers of NETs. Here, we aimed to target the inhibition of NET formation (NETosis) to alleviate CIPN.

METHODS

Oxaliplatin (L-OHP) was used to establish a CIPN model. The mice were pretreated with fucoidan to investigate the therapeutic effect. SR-A1-/- mice were used to examine the role of scavenger receptor A1 (SR-A1) in CIPN. Bone marrow-derived macrophages (BMDMs) isolated from SR-A1-/- mice and WT mice were used to investigate the mechanism by which macrophage phagocytosis of NETs alleviates CIPN.

RESULTS

Clinically, we found that the contents of LPS, HMGB1 and NETs in the plasma of CIPN patients were significantly increased and positively correlated with the VAS score. Fucoidan decreased the LPS/HMGB1/NET contents and relieved CIPN in mice. Mechanistically, fucoidan upregulated SR-A1 expression and promoted the phagocytosis of LPS/HMGB1 by BMDMs. Fucoidan also facilitated the engulfment of NETs by BMDMs via the recognition and localization of SR-A1 and HMGB1. The therapeutic effects of fucoidan were abolished by SR-A1 knockout. RNA-seq analysis revealed that fucoidan increased sqstm1 (p62) gene expression. Fucoidan promoted the competitive binding of sqstm1 and Nrf2 to Keap1, increasing Nrf2 nuclear translocation and SR-A1 transcription. Additionally, the sequencing analysis (16 S) of microbial diversity revealed that fucoidan increased the gut microbiota diversity and abundance and increased the Bacteroides/Firmicutes ratio.

CONCLUSIONS

Altogether, fucoidan promotes the SR-A1-mediated phagocytosis of LPS/HMGB1/NETs and maintains gut microbial homeostasis, which may provide a potential therapeutic strategy for CIPN.

Chemokines: Orchestration of the Tumor Microenvironment and Control of Hepatocellular Carcinoma Progression

Chemokines, a family of chemotactic cytokines, play a central role in shaping the tumor microenvironment (TME) and in influencing the progression of hepatocellular carcinoma (HCC), a well-known inflammation-related cancer. This review addresses the intricate interplay between chemokines and HCC and highlights their multifaceted role. We discuss how altered expression of chemokines within the TME contributes to the development of HCC by orchestrating the recruitment of immune cells, ultimately leading to immunosuppression. In addition, we are investigating the contribution of chemokines to important features of HCC progression, including angiogenesis and epithelial-mesenchymal transition (EMT). The potential of chemokines as serum biomarkers for HCC diagnosis and their potential as novel therapeutic targets are also explored. This comprehensive review emphasizes the importance of chemokines in the pathogenesis of HCC and their potential for a better understanding and treatment of this difficult disease.

How oxygenation shapes immune responses: emerging roles for physioxia and pathological hypoxia

Most eukaryotes require oxygen for their survival and, with increasing multicellular complexity, oxygen availability and delivery rates vary across the tissues of complex organisms. In humans, healthy tissues have markedly different oxygen gradients, ranging from the hypoxic environment of the bone marrow (where our haematopoietic stem cells reside) to the lungs and their alveoli, which are among the most oxygenated areas of the body. Immune cells are therefore required to adapt to varying oxygen availability as they move from the bone marrow to peripheral organs to mediate their effector functions. These changing oxygen gradients are exaggerated during inflammation, where oxygenation is often depleted owing to alterations in tissue perfusion and increased cellular activity. As such, it is important to consider the effects of oxygenation on shaping the immune response during tissue homeostasis and disease conditions. In this Review, we address the relevance of both physiological oxygenation (physioxia) and disease-associated hypoxia (where cellular oxygen demand outstrips supply) for immune cell functions, discussing the relevance of hypoxia for immune responses in the settings of tissue homeostasis, inflammation, infection, cancer and disease immunotherapy.

Neutrophil extracellular traps in tumor metabolism and microenvironment

Neutrophil extracellular traps (NETs) are intricate, web-like formations composed of DNA, histones, and antimicrobial proteins, released by neutrophils. These structures participate in a wide array of physiological and pathological activities, including immune rheumatic diseases and damage to target organs. Recently, the connection between NETs and cancer has garnered significant attention. Within the tumor microenvironment and metabolism, NETs exhibit multifaceted roles, such as promoting the proliferation and migration of tumor cells, influencing redox balance, triggering angiogenesis, and driving metabolic reprogramming. This review offers a comprehensive analysis of the link between NETs and tumor metabolism, emphasizing areas that remain underexplored. These include the interaction of NETs with tumor mitochondria, their effect on redox states within tumors, their involvement in metabolic reprogramming, and their contribution to angiogenesis in tumors. Such insights lay a theoretical foundation for a deeper understanding of the role of NETs in cancer development. Moreover, the review also delves into potential therapeutic strategies that target NETs and suggests future research directions, offering new perspectives on the treatment of cancer and other related diseases.

PD-L1 positive platelets mediate resistance to immune checkpoint inhibitors in patients with colorectal cancer

BACKGROUND

Programmed cell death ligand 1 (PD-L1) expression on immune cells is correlated with the efficacy of immune checkpoint inhibitor (ICI) therapy in various types of cancer. Platelets are important components of the tumour microenvironment (TME) and are widely involved in the development of many types of cancer including colorectal cancer (CRC). However, the role of PD-L1 positive platelets in ICI therapy for CRC remains unknown. We hypothesized that PD-L1 positive platelets trigger and sustain CRC immunosuppression.

METHODS

The functional depletion effects of PD-L1 positive platelets on TME and immune cells were measured via western blotting, immunofluorescence staining, qRT-PCR, ELISpot and flow cytometry. In vivo, CD274 knockout (KO), CD8a KO, platelet-specific KO (PF4-Cre-Hsp90b1flox/flox) mouse models and a subcutaneous tumour model treated with aspirin and PD-L1 mAb were established in C57BL/6 N mice.

RESULTS

We found that PD-L1 positive platelets are correlated with a poor prognosis, CD8 + T cell exhaustion and serve as a novel noninvasive biomarker for predicting immunotherapy efficacy in patients with CRC. The transfer of PD-L1 from tumour cells to platelets in the TME depends on direct cell contact via the fibronectin-1/GPIbα/integrin α5β1 pathway. In turn, platelets can also induce PD-L1 expression on cancer cells. Animal experiments revealed that antiplatelet pharmacological agents and genetic knockout of platelets potentiated the antitumour effect of the PD-L1 mAb treatment in a CD8 + T cell dependent manner.

CONCLUSIONS

Our data suggest that PD-L1 positive platelets suppress CD8 + T cell immunity. Clinical combination treatment with ICIs and antiplatelet agents may be an effective therapeutic strategy for treating CRC.

Tumor metastasis and recurrence: The role of perioperative NETosis

Although surgical resection of tumor mass remains the mainstay of curative therapeutic management for solid tumors, accumulating studies suggest that these procedures promote tumor recurrence and metastasis. Regarded as the first immune cells to fight against infectious or inflammatory insults from surgery, neutrophils along with their ability of neutrophil extracellular traps (NETs) production has attracted much attention. A growing body of evidence suggests that NETs promote cancer metastasis by stimulating various stages, including local invasion, colonization, and growth. Therefore, we discussed the mechanism of NETosis induced by surgical stress and tumor cells, and the contribution of NETs on tumor metastasis: aid in the tumor cell migration and proliferation, evasion of immune surveillance, circulating tumor cell adhesion and establishment of a metastatic niche. Lastly, we summarized existing NET-targeting interventions, offering recent insights into potential targets for clinical intervention.

Angiogenesis, a key point in the association of gut microbiota and its metabolites with disease

The gut microbiota is a complex and dynamic ecosystem that plays a crucial role in human health and disease, including obesity, diabetes, cardiovascular diseases, neurodegenerative diseases, inflammatory bowel disease, and cancer. Chronic inflammation is a common feature of these diseases and is closely related to angiogenesis (the process of forming new blood vessels), which is often dysregulated in pathological conditions. Inflammation potentially acts as a central mediator. This abstract aims to elucidate the connection between the gut microbiota and angiogenesis in various diseases. The gut microbiota influences angiogenesis through various mechanisms, including the production of metabolites that directly or indirectly affect vascularization. For example, short-chain fatty acids (SCFAs) such as butyrate, propionate, and acetate are known to regulate immune responses and inflammation, thereby affecting angiogenesis. In the context of cardiovascular diseases, the gut microbiota promotes atherosclerosis and vascular dysfunction by producing trimethylamine N-oxide (TMAO) and other metabolites that promote inflammation and endothelial dysfunction. Similarly, in neurodegenerative diseases, the gut microbiota may influence neuroinflammation and the integrity of the blood-brain barrier, thereby affecting angiogenesis. In cases of fractures and wound healing, the gut microbiota promotes angiogenesis by activating inflammatory responses and immune effects, facilitating the healing of tissue damage. In cancer, the gut microbiota can either inhibit or promote tumor growth and angiogenesis, depending on the specific bacterial composition and their metabolites. For instance, some bacteria can activate inflammasomes, leading to the production of inflammatory factors that alter the tumor immune microenvironment and activate angiogenesis-related signaling pathways, affecting tumor angiogenesis and metastasis. Some bacteria can directly interact with tumor cells, activating angiogenesis-related signaling pathways. Diet, as a modifiable factor, significantly influences angiogenesis through diet-derived microbial metabolites. Diet can rapidly alter the composition of the microbiota and its metabolic activity, thereby changing the concentration of microbial-derived metabolites and profoundly affecting the host's immune response and angiogenesis. For example, a high animal protein diet promotes the production of pro-atherogenic metabolites like TMAO, activating inflammatory pathways and interfering with platelet function, which is associated with the severity of coronary artery plaques, peripheral artery disease, and cardiovascular diseases. A diet rich in dietary fiber promotes the production of SCFAs, which act as ligands for cell surface or intracellular receptors, regulating various biological processes, including inflammation, tissue homeostasis, and immune responses, thereby influencing angiogenesis. In summary, the role of the gut microbiota in angiogenesis is multifaceted, playing an important role in disease progression by affecting various biological processes such as inflammation, immune responses, and multiple signaling pathways. Diet-derived microbial metabolites play a crucial role in linking the gut microbiota and angiogenesis. Understanding the complex interactions between diet, the gut microbiota, and angiogenesis has the potential to uncover novel therapeutic targets for managing these conditions. Therefore, interventions targeting the gut microbiota and its metabolites, such as through fecal microbiota transplantation (FMT) and the application of probiotics to alter the composition of the gut microbiota and enhance the production of beneficial metabolites, present a promising therapeutic strategy.

The Effect of Systemic Immune-Inflammatory Index (SII) and Prognostic Nutritional Index (PNI) in Early Gastric Cancer

Background

In recent years, the systemic immune-inflammatory index (SII) and prognostic nutritional index (PNI) have been considered potential predictors of survival outcomes in various solid tumors, including gastric cancer. However, there is a notable lack of research focusing on their prognostic implications specifically in the early stage of gastric cancer. This study aims to investigate the prognostic indicators of early gastric cancer (EGC), including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), SII, PNI, and lymph node metastasis (LNM).

Methods

In this retrospective analysis, we examined 490 patients diagnosed with EGC (pT1Nx). The peripheral blood indices of interest were SII, PNI, PLR, and NLR. The receiver operating characteristic (ROC) curves and the area under the ROC curve (AUC) were used to determine optimal cutoff values and prognostic efficacy for each parameter. Additionally, Kaplan-Meier survival curves and multivariate Cox regression models were utilized to delineate independent prognostic factors.

Results

The optimal cutoff values for SII and PNI were determined as 613.05 and 42.21, respectively. Patients in the low SII (SII-L) group demonstrated significantly higher 5-year Disease-Free Survival (DFS) and Overall Survival (OS) rates of 94.7% and 96.2%, compared to the high SII (SII-H) group (DFS: 78.7%; OS: 81.9%), with both differences proving statistically significant (P < 0.001, P < 0.001). Similarly, patients in the high PNI (PNI-H) group showed superior 5-year DFS (93.3%) and OS rates (95.1%) versus the low PNI (PNI-L) group (DFS: 71.4%; OS: 74.3%), also demonstrating statistical significance (P < 0.001, P < 0.001). Multivariate analysis identified SII, PNI, and LNM as independent prognostic factors for EGC. A combined analysis of SII, PNI, and LNM yielded a C-index of 0.723 (P = 0.008).

Conclusion

SII, PNI, and LNM are effective markers for predicting the survival outcomes of patients undergoing radical gastrectomy for EGC.

S100A9 promotes renal calcium oxalate stone formation via activating the TLR4-p38/MAPK-LCN2 signaling pathway

OBJECTIVES

To explore the role of S100A9 protein in renal calcium oxalate (CaOx) stone formation.

METHODS

CaOx nephrocalcinosis mice were established via intraperitoneal injection of glyoxylate. They were treated with S100A9 deficiency, Paquinimod, or p38 MAPK-IN-1. Vonkossa staining was conducted to observe the deposition of CaOx crystals. Renal expression of inflammation, macrophage polarization, and injury markers was detected using immunohistochemistry and qPCR. Effects of S100A9 on renal tubular epithelial cells (HK-2) were explored by transcriptome sequencing. The mechanism of how S100A9 regulated lipocalin 2 (LCN2) was studied through Western Blot. Flow cytometry was performed to detect the influence of LCN2 on macrophages polarization.

RESULTS

S100A9 deficiency inhibited the renal deposition of CaOx crystals in nephrocalcinosis mice. S100A9 upregulated the expression of LCN2 in HK-2 cells via activating the TLR4-p38/MAPK pathway. LCN2 promoted the migration and M1 polarization of macrophages. S100A9 deficiency downregulated the renal expression of LCN2, IL1-β, Kim-1, F4/80, and CD80 in nephrocalcinosis mice. Paquinimod and p38 MAPK-IN-1 both inhibited the renal deposition of CaOx crystals and downregulated the expression of LCN2, IL1-β, Kim-1, F4/80, iNOS, and CD68 in nephrocalcinosis mice.

CONCLUSIONS

S100A9 promotes renal inflammatory injury by activating the TLR4-p38/MAPK-LCN2 pathway and then contributes to CaOx stone formation.

Didang decoction attenuates cancer-associated thrombosis by inhibiting PAD4-dependent NET formation in lung cancer

This research aims to investigate the impact of Didang decoction (DD) on the formation of neutrophil extracellular traps (NETs) and cancer-associated thrombosis in lung cancer. BALB/c nude mice were used to establish xenograft models for inducing deep vein thrombosis. Tumor growth and thrombus length were assessed. The impact of DD on NET generation was analyzed using enzyme-linked immunosorbent assay, immunofluorescence staining, quantitative real-time PCR, and western blot analysis, both in vivo and in vitro. CI-amidine, a PAD4 inhibitor, was employed to evaluate the role of PAD4 in the generation of NETs. In vivo studies demonstrated that treatment with DD reduced tumor growth, inhibited thrombus formation, and decreased the levels of NET markers in the serum, tumor tissues, neutrophils, and thrombus tissues of mice. Additional data indicated that DD could suppress neutrophil counts, the release of tissue factor (TF), and the activation of thrombin-activated platelets, all of which contributed to increased formation of NETs in mouse models. In vitro, following incubation with conditioned medium (CM) derived from Lewis lung carcinoma cells, the expression of NET markers in neutrophils was significantly elevated, and an extracellular fibrous network structure was observed. Nevertheless, these NET-associated changes were partially counteracted by DD. Additionally, CI-amidine reduced the expression of NET markers in CM-treated neutrophils, consistent with the effects of DD. Collectively, DD inhibits cancer-associated thrombosis in lung cancer by decreasing PAD4-dependent NET formation through the regulation of TF-mediated thrombin-platelet activation. This presents a promising therapeutic strategy for preventing and treating venous thromboembolism in lung cancer.

Neutrophil extracellular traps in homeostasis and disease

Neutrophil extracellular traps (NETs), crucial in immune defense mechanisms, are renowned for their propensity to expel decondensed chromatin embedded with inflammatory proteins. Our comprehension of NETs in pathogen clearance, immune regulation and disease pathogenesis, has grown significantly in recent years. NETs are not only pivotal in the context of infections but also exhibit significant involvement in sterile inflammation. Evidence suggests that excessive accumulation of NETs can result in vessel occlusion, tissue damage, and prolonged inflammatory responses, thereby contributing to the progression and exacerbation of various pathological states. Nevertheless, NETs exhibit dual functionalities in certain pathological contexts. While NETs may act as autoantigens, aggregated NET complexes can function as inflammatory mediators by degrading proinflammatory cytokines and chemokines. The delineation of molecules and signaling pathways governing NET formation aids in refining our appreciation of NETs' role in immune homeostasis, inflammation, autoimmune diseases, metabolic dysregulation, and cancer. In this comprehensive review, we delve into the multifaceted roles of NETs in both homeostasis and disease, whilst discussing their potential as therapeutic targets. Our aim is to enhance the understanding of the intricate functions of NETs across the spectrum from physiology to pathology.

Innate immune cells in tumor microenvironment: A new frontier in cancer immunotherapy

Innate immune cells, crucial in resisting infections and initiating adaptive immunity, play diverse and significant roles in tumor development. These cells, including macrophages, granulocytes, dendritic cells (DCs), innate lymphoid cells, and innate-like T cells, are pivotal in the tumor microenvironment (TME). Innate immune cells are crucial components of the TME, based on which various immunotherapy strategies have been explored. Immunotherapy strategies, such as novel immune checkpoint inhibitors, STING/CD40 agonists, macrophage-based surface backpack anchoring, ex vivo polarization approaches, DC-based tumor vaccines, and CAR-engineered innate immune cells, aim to enhance their anti-tumor potential and counteract cancer-induced immunosuppression. The proximity of innate immune cells to tumor cells in the TME also makes them excellent drug carriers. In this review, we will first provide a systematic overview of innate immune cells within the TME and then discuss innate cell-based therapeutic strategies. Furthermore, the research obstacles and perspectives within the field will also be addressed.

The therapeutic targets and signaling mechanisms of ondansetron in the treatment of critical illness in the ICU

Background

There is accumulating evidence regarding the benefits of the 5-HT3 receptor antagonist ondansetron for the treatment of critical illness due to its potential anti-inflammatory effect. This study attempted to determine the potential targets and molecular mechanisms of ondansetron's action against critical illnesses.

Methods

A bioinformatics analysis of network pharmacology was conducted to demonstrate screening targets and the signaling pathways of ondansetron action against the most common critical illnesses such as acute kidney injury (AKI), sepsis, and acute respiratory distress syndrome (ARDS). Experiments of LPS-stimulated rat neutrophils with ondansetron treatment were conducted to further validate the relevant hypothesis.

Results

A total of 198, 111, and 26 primary causal targets were identified from the data for the action of ondansetron against AKI, sepsis, and ARDS respectively. We found that the pathway of neutrophil extracellular traps (NETs) formation is statistically significantly involved in the action of ondansetron against these three critical illnesses. In the pathway of NETs formation, the common drug-disease intersection targets in these three critical illnesses were toll-like receptor 8 (TLR8), mitogen-activated protein kinase-14 (MAPK14), nuclear factor kappa-B1 (NFKB1), neutrophil elastase (NE), and myeloperoxidase (MPO). Considering these bioinformatics findings, we concluded that ondansetron anti-critical illness effects are mechanistically and pharmacologically implicated with suppression of neutrophils-associated inflammatory processes. It was also showed that after treatment of LPS-stimulated rat neutrophils with ondansetron, the key proteins NE, MPO, and Peptide Arginine Deaminase 4 (PAD4) in the NETs formation were significantly reduced, and the inflammatory factors IL-6, IL-1β, TNF-α, and chemokine receptor (CXCR4) were also significantly decreased.

Conclusion

The excessive formation of NETs may have important research value in the development and progression of critical illness. Ondansetron may reduce excessive inflammatory injury in critical diseases by reducing the formation of NETs via influencing the five targets: TLR8, NFKB1, MAPK14, NE, and MPO. Ondansetron and these primary predictive biotargets may potentially be used to treat critical illness in future clinical practice.

NETs: Important players in cancer progression and therapeutic resistance

Neutrophil extracellular traps (NETs) are web-like structures composed of cytoplasmic contents, DNA chromatin and various granular proteins released by neutrophils in response to viruses, bacteria, immune complexes and cytokines. Studies have shown that NETs can promote the occurrence, development and metastasis of tumors. In this paper, the mechanism underlying the formation and degradation of NETs and the malignant biological behaviors of NETs, such as the promotion of tumor cell proliferation, epithelial mesenchymal transition, extracellular matrix remodeling, angiogenesis, immune evasion and tumor-related thrombosis, are described in detail. NETs are being increasingly studied as therapeutic targets for tumors. We have summarized strategies for targeting NETs or interfering with NET-cancer cell interactions and explored the potential application value of NETs as biomarkers in cancer diagnosis and treatment, as well as the relationship between NETs and therapeutic resistance.

Hot under the clot: venous thrombogenesis is an inflammatory process

ABSTRACT

Venous thrombosis (VT) is a serious medical condition in which a blood clot forms in deep veins, often causing limb swelling and pain. Current antithrombotic therapies carry significant bleeding risks resulting from targeting essential coagulation factors. Recent advances in this field have revealed that the cross talk between the innate immune system and coagulation cascade is a key driver of VT pathogenesis, offering new opportunities for potential therapeutic interventions without inducing bleeding complications. This review summarizes and discusses recent evidence from preclinical models on the role of inflammation in VT development. We highlight the major mechanisms by which endothelial cell activation, Weibel-Palade body release, hypoxia, reactive oxygen species, inflammasome, neutrophil extracellular traps, and other immune factors cooperate to initiate and propagate VT. We also review emerging clinical data describing anti-inflammatory approaches as adjuncts to anticoagulation in VT treatment. Finally, we identify key knowledge gaps and future directions that could maximize the benefit of anti-inflammatory therapies in VT. Identifying and targeting the inflammatory factors driving VT, either at the endothelial cell level or within the clot, may pave the way for new therapeutic possibilities for improving VT treatment and reducing thromboembolic complications without increasing bleeding risk.

Deciphering the roles of the HMGB family in cancer: Insights from subcellular localization dynamics

The high-mobility group box (HMGB) family consists of four DNA-binding proteins that regulate chromatin structure and function. In addition to their intracellular functions, recent studies have revealed their involvement as extracellular damage-associated molecular patterns (DAMPs), contributing to immune responses and tumor development. The HMGB family promotes tumorigenesis by modulating multiple processes including proliferation, metabolic reprogramming, metastasis, immune evasion, and drug resistance. Due to the predominant focus on HMGB1 in the literature, little is known about the remaining members of this family. This review summarizes the structural, distributional, as well as functional similarities and distinctions among members of the HMGB family, followed by a comprehensive exploration of their roles in tumor development. We emphasize the distributional and functional hierarchy of the HMGB family at both the organizational and subcellular levels, with a focus on their relationship with the tumor immune microenvironment (TIME), aiming to prospect potential strategies for anticancer therapy.

Targeting NETosis: nature's alarm system in cancer progression

Neutrophils are recognized active participants in inflammatory responses and are intricately linked to cancer progression. In response to inflammatory stimuli, neutrophils become activated, releasing neutrophils extracellular traps (NETs) for the capture and eradication of pathogens, a phenomenon termed NETosis. With a deeper understanding of NETs, there is growing evidence supporting their role in cancer progression and their involvement in conferring resistance to various cancer therapies, especially concerning tumor reactions to chemotherapy, radiation therapy (RT), and immunotherapy. This review summarizes the roles of NETs in the tumor microenvironment (TME) and their mechanisms of neutrophil involvement in the host defense. Additionally, it elucidates the mechanisms through which NETs promote tumor progression and their role in cancer treatment resistance, highlighting their potential as promising therapeutic targets in cancer treatment and their clinical applicability.

A Two-Pronged Delivery Strategy Disrupting Positive Feedback Loop of Neutrophil Extracellular Traps for Metastasis Suppression

Neutrophil extracellular traps (NETs) severely affect tumor metastasis through a self-perpetuating feedback loop involving two key steps: (1) mitochondrial aerobic respiration-induced hypoxia promotes NET formation and (2) NETs enhance mitochondrial metabolism to exacerbate hypoxia. Herein, we propose a two-pronged approach with the activity of NET-degrading and mitochondrion-damaging by simultaneously targeting drugs to NETs and tumor mitochondria of this loop. In addition to specifically recognizing and eliminating extant NETs, the NET-targeting nanoparticle also reduces NET-induced mitochondrial biogenesis, thus inhibiting the initial step of the feedback loop and mitigating extant NETs' impact on tumor metastasis. Simultaneously, the mitochondrion-targeting system intercepts mitochondrial metabolism and alleviates tumor hypoxia, inhibiting neutrophil infiltration and subsequent NET formation, which reduces the source of NETs and disrupts another step of the self-amplifying feedback loop. Together, the combination significantly reduces the formation of NET-tumor cell clusters by disrupting the interaction between NETs and tumor mitochondria, thereby impeding the metastatic cascade including tumor invasion, hematogenous spread, and distant colonization. This work represents an innovative attempt to disrupt the feedback loop in tumor metastasis, offering a promising therapeutic approach restraining NET-assisted metastasis.

Platelet factor 4 promotes deep venous thrombosis by regulating the formation of neutrophil extracellular traps

The presence of neutrophil extracellular traps (NETs) in thrombotic diseases has been extensively studied. The exact mechanism of NET formation in deep venous thrombosis (DVT) has not been largely studied. This study is aimed to explore the role of NETs and their interaction with platelet factor 4 (PF4) in DVT. In plasma samples from 51 healthy volunteers and 52 DVT patients, NET markers and PF4 were measured using enzyme-linked immunosorbent assays (ELISA). NET generation in blood samples from healthy subjects and DVT patients was analyzed by confocal microscopy and flow cytometry. The plasma levels of NETs were significantly elevated in DVT patients, and neutrophils from patients showed a stronger ability to generate NETs after treatment. PF4 was upregulated in plasma samples from DVT patients and mediated NET formation. NETs enhanced procoagulant (PCA) via tissue factor and activating platelets to induce procoagulant activity. In addition, we established an inferior vena cava ligation (IVC) model to examine the role of NETs in thrombogenicity in DVT. In conclusion, NET formation was mediated by PF4 and enhance the procoagulant activity in DVT.

Identification of neutrophil extracellular trap-driven gastric cancer heterogeneity and C5AR1 as a therapeutic target

Neutrophil extracellular traps (NETs) are implicated in gastric cancer (GC) growth, metastatic dissemination, cancer-associated thrombosis, etc. This work is conducted to elucidate the heterogeneity of NETs in GC. The transcriptome heterogeneity of NETs is investigated in TCGA-STAD via a consensus clustering algorithm, with subsequent external verification in the GSE88433 and GSE88437 cohorts. Clinical and molecular traits, the immune microenvironment, and drug response are characterized in the identified NET-based clusters. Based upon the feature genes of NETs, a classifier is built for estimating NET-based clusters via machine learning. Multiple experiments are utilized to verify the expressions and implications of the feature genes in GC. A novel NET-based classification system is proposed for reflecting the heterogeneity of NETs in GC. Two NET-based clusters have unique and heterogeneous clinical and molecular features, immune microenvironments, and responses to targeted therapy and immunotherapy. A logistic regression model reliably differentiates the NET-based clusters. The feature genes C5AR1, CSF1R, CSF2RB, CYBB, HCK, ITGB2, LILRB2, MNDA, MPEG1, PLEK, SRGN, and STAB1 are proven to be aberrantly expressed in GC cells. Specific knockdown of C5AR1 effectively hinders GC cell growth and elicits intracellular ROS accumulation. In addition, its suppression suppresses the aggressiveness and EMT phenotype of GC cells. In all, NETs are the main contributors to intratumoral heterogeneity and differential drug sensitivity in GC, and C5AR1 has been shown to trigger GC growth and metastatic spread. These findings collectively provide a theoretical basis for the use of anti-NETs in GC treatment.

Neutrophil extracellular traps promote gastric cancer cell metastasis via the NAT10-mediated N4-acetylcytidine modification of SMYD2

It has been reported that the formation of neutrophil extracellular traps (NETs) is associated with cancer metastasis. The current study aimed to explore the effects of NETs on gastric cancer (GC) cell metastasis and uncover their underlying mechanism. NETs were measured in the plasma of patients with GC. Then, GC cells were treated with NETs to assess cell viability, migration, and invasion using cell counting kit 8 and Transwell assay, The liver metastasis and xenograft tumor mouse models were established to assess tumor growth and metastasis. The N4-acetylcytidine (ac4C) modification of SET and MYND domain containing 2 (SMYD2) mediated by NAT10 was evaluated using acetylated RNA immunoprecipitation. The results showed that the level of NETs was increased in the plasma of patients with GC, particularly in those with metastatic GC. In addition, GC cell co-treatment with NETs promoted cell viability, migration and invasion, while NAT10 or SMYD2 knockdown abrogated this effect. NAT10 also promoted the ac4C modification of SMYD2, thus increasing SMYD2 stability. Furthermore, NETs promoted the metastasis of GC cells in the liver in vivo. Overall, the results of the present study demonstrated that NETs promoted GC cell metastasis via the NAT10-mediated ac4C modification of SMYD2. These findings suggested that inhibiting the formation of NETs could be an effective approach for attenuating GC progression.

Inhibition of HMGB1 improves experimental mice colitis by mediating NETs and macrophage polarization

OBJECTIVE

Inflammatory bowel disease (IBD) is listed by the World Health Organization as one of the modern intractable diseases. High mobility histone box 1 (HMGB1), originally described as a non-histone nucleoprotein involved in transcriptional regulation, was later identified as a pro-inflammatory cytokine that may contribute to the pathogenesis of inflammatory diseases such as IBD. Neutrophil extracellular traps (NETs) play an important role in the pathophysiology of IBD The aim of this study was to investigate the role of HMGB1 in experimental colitis mice and its potential mechanisms of action.

METHODS

We first constructed the experimental colitis mouse model. Intervention of mice by rhHMGB1 supplementation or HMGB1 inhibition. The pathological morphology of the colon was observed using HE staining. Apoptosis of colonic tissue intestinal epithelial cells was evaluated using Tunel assay. The expression of HMGB1, ZO-1 and occludin in colon tissue was detected by immunohistochemistry, ELISA and western-blot. We also assessed the effects of HMGB1 on colonic injury, NETs content, macrophage polarization and inflammatory cells in mice. The regulatory effect of HMGB1 inhibition on NETs was assessed by combining DNase I.

RESULTS

Inhibition of HMGB1 significantly reduced the inflammatory model in experimental colitis mice, as evidenced by reduced body weight, increased colonic length, reduced DAI scores and apoptosis, reduced inflammatory response, and improved colonic histopathological morphology and intestinal mucosal barrier function. Meanwhile, inhibition of HMGB1 was able to reduce the expression of CD86, citH3 and MPO and increase the expression of CD206 in the colonic tissue of mice. In addition, DNase I intervention was also able to improve colonic inflammation in mice. And the best effect was observed when DNase I and inhibition of HMGB1 were intervened together.

CONCLUSION

Inhibition of HMGB1 ameliorates IBD by mediating NETs and macrophage polarization.

Regulation of neutrophil extracellular traps in cancer

Neutrophil extracellular trap (NET) is one of the defense functions of neutrophils, which has a rapid ability to kill infections and is also crucial in a variety of immune-associated diseases including infections, tumors and autoimmune diseases. Recent studies have shown that NETs are closely related to the development of tumors. The regulatory role of NETs in tumors has been of interest to researchers. In addition to awakening latent tumor cells, NETs can also promote the proliferation and development of tumor cells and their metastasis to other sites. At the same time, NETs also have the effect of inhibiting tumors. At present, there are some new advances in the impact of NETs on tumor development, which will provide a more theoretical basis for developing NET-targeted drugs. Therefore, this review just summarized the formation process of NETs, the regulation of tumor development and the treatment methods based on NETs.

Emerging roles of MITF as a crucial regulator of immunity

Microphthalmia-associated transcription factor (MITF), a basic helix-loop-helix leucine zipper transcription factor (bHLH-Zip), has been identified as a melanocyte-specific transcription factor and plays a critical role in melanocyte survival, differentiation, function, proliferation and pigmentation. Although numerous studies have explained the roles of MITF in melanocytes and in melanoma development, the function of MITF in the hematopoietic or immune system-beyond its function in melanin-producing cells-is not yet fully understood. However, there is convincing and increasing evidence suggesting that MITF may play multiple important roles in immune-related cells. Therefore, this review is focused on recent advances in elucidating novel functions of MITF in cancer progression and immune responses to cancer. In particular, we highlight the role of MITF as a central modulator in the regulation of immune responses, as elucidated in recent studies.

NETosis: Sculpting tumor metastasis and immunotherapy

The process of neutrophil extracellular traps (NETs) formation, called NETosis, is a peculiar death modality of neutrophils, which was first observed as an immune response against bacterial infection. However, recent work has revealed the unique biology of NETosis in facilitating tumor metastatic process. Neutrophil extracellular traps released by the tumor microenvironment (TME) shield tumor cells from cytotoxic immunity, leading to impaired tumor clearance. Besides, tumor cells tapped by NETs enable to travel through vessels and subsequently seed distant organs. Targeted ablation of NETosis has been proven to be beneficial in potentiating the efficacy of cancer immunotherapy in the metastatic settings. This review outlines the impact of NETosis at almost all stages of tumor metastasis. Furthermore, understanding the multifaceted interplay between NETosis and the TME components is crucial for supporting the rational development of highly effective combination immunotherapeutic strategies with anti-NETosis for patients with metastatic disease.

TF/PAR2 Signaling Axis Supports the Protumor Effect of Neutrophil Extracellular Traps (NETs) on Human Breast Cancer Cells

Neutrophil extracellular traps (NETs) have been implicated in several hallmarks of cancer. Among the protumor effects, NETs promote epithelial-mesenchymal transition (EMT) in different cancer models. EMT has been linked to an enhanced expression of the clotting-initiating protein, tissue factor (TF), thus favoring the metastatic potential. TF may also exert protumor effects by facilitating the activation of protease-activated receptor 2 (PAR2). Herein, we evaluated whether NETs could induce TF expression in breast cancer cells and further promote procoagulant and intracellular signaling effects via the TF/PAR2 axis. T-47D and MCF7 cell lines were treated with isolated NETs, and samples were obtained for real-time PCR, flow cytometry, Western blotting, and plasma coagulation assays. In silico analyses were performed employing RNA-seq data from breast cancer patients deposited in The Cancer Genome Atlas (TCGA) database. A positive correlation was observed between neutrophil/NETs gene signatures and TF gene expression. Neutrophils/NETs gene signatures and PAR2 gene expression also showed a significant positive correlation in the bioinformatics model. In vitro analysis showed that treatment with NETs upregulated TF gene and protein expression in breast cancer cell lines. The inhibition of ERK/JNK reduced the TF gene expression induced by NETs. Remarkably, the pharmacological or genetic inhibition of the TF/PAR2 signaling axis attenuated the NETs-induced expression of several protumor genes. Also, treatment of NETs with a neutrophil elastase inhibitor reduced the expression of metastasis-related genes. Our results suggest that the TF/PAR2 signaling axis contributes to the pro-cancer effects of NETs in human breast cancer cells.

Disulfide-HMGB1 signals through TLR4 and TLR9 to induce inflammatory macrophages capable of innate-adaptive crosstalk in human liver transplantation

Ischemia-reperfusion injury (IRI) during orthotopic liver transplantation (OLT) contributes to graft rejection and poor clinical outcomes. The disulfide form of high mobility group box 1 (diS-HMGB1), an intracellular protein released during OLT-IRI, induces pro-inflammatory macrophages. How diS-HMGB1 differentiates human monocytes into macrophages capable of activating adaptive immunity remains unknown. We investigated if diS-HMGB1 binds toll-like receptor (TLR) 4 and TLR9 to differentiate monocytes into pro-inflammatory macrophages that activate adaptive immunity and promote graft injury and dysfunction. Assessment of 106 clinical liver tissue and longitudinal blood samples revealed that OLT recipients were more likely to experience IRI and graft dysfunction with increased diS-HMGB1 released during reperfusion. Increased diS-HMGB1 concentration also correlated with TLR4/TLR9 activation, polarization of monocytes into pro-inflammatory macrophages, and production of anti-donor antibodies. In vitro, healthy volunteer monocytes stimulated with purified diS-HMGB1 had increased inflammatory cytokine secretion, antigen presentation machinery, and reactive oxygen species production. TLR4 inhibition primarily impeded cytokine/chemokine and costimulatory molecule programs, whereas TLR9 inhibition decreased HLA-DR and reactive oxygen species production. diS-HMGB1-polarized macrophages also showed increased capacity to present antigens and activate T memory cells. In murine OLT, diS-HMGB1 treatment potentiated ischemia-reperfusion-mediated hepatocellular injury, accompanied by increased serum alanine transaminase levels. This translational study identifies the diS-HMGB1/TLR4/TLR9 axis as potential therapeutic targets in OLT-IRI recipients.

Immune responses of six-transmembrane epithelial antigen of the prostate 4 functions as a novel biomarker in gastric cancer

BACKGROUND

Immune cells play an important role in regulating the behavior of tumor cells. According to emerging evidence, six-transmembrane epithelial antigen of the prostate 4 (STEAP4) performs a crucial part in tumor microenvironmental immune response and tumorigenesis, and serves as the potential target for cellular and antibody immunotherapy. However, the immunotherapeutic role of STEAP4 in gastric cancer (GC) remains unclear.

AIM

To investigate the expression of STEAP4 in GC and its relationship with immune infiltrating cells, and explore the potential value of STEAP4 as an immune prognostic indicator in GC.

METHODS

The expression level of STEAP4 was characterized by immunohistochemistry in tumors and adjacent non-cancerous samples in 96 GC patients. Tumor Immune Estimation Resource was used to study the correlation between STEAP4 and tumor immune infiltration level and immune infiltration gene signature. R package was used to analyze the relationship between STEAP4 expression and immune and stromal scores in GC (GSE62254) by the ESTIMATE algorithm, and Kaplan-Meier Plotter and Gene Expression Profiling Interactive Analysis were applied to analyze the effect of STEAP4 on clinical prognosis.

RESULTS

Immunohistochemistry analysis showed that STEAP4 expression was higher in GC tissues than in adjacent tissues, and STEAP4 expression was positively correlated with the clinical stage of GC. In GC, the expression of STEAP4 was positively correlated with the infiltration levels of B cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells. The expression level of STEAP4 was strongly correlated with most of the immune markers. In addition, STEAP4 expression was inversely correlated with tumor purity, but correlated with stromal score (r = 0.43, P < 0.001), immune score (r = 0.29, P < 0.001) and estimate score (r = 0.39, P < 0.001). Moreover, stromal, immune, and estimate scores were higher in the STEAP4 high expression group, whereas tumor purity was higher in the STEAP4 Low expression group. The relationship between STEAP4 expression and prognosis of patients with GC was further investigated, and the results showed that high STEAP4 expression was associated with poor overall survival and disease-free survival. In addition, Kaplan-Meier Plotter showed that high expression of STEAP4 was significantly correlated with poor survival of patients with GC.

CONCLUSION

The current findings suggest an oncogenic role for STEAP4 in GC, with significantly high levels being associated with poor prognosis. Investigation of the GC tumor microenvironment suggests the potential function of STEAP4 is connected with the infiltration of diverse immune cells, which may contribute to the regulation of the tumor microenvironment. In conclusion, STEAP4 may serve as a potential therapeutic target for GC to improve the immune infiltration, as well as serve as a prognostic biomarker for judging the prognosis and immune infiltration status of GC.

Neutrophil extracellular traps promote angiogenesis in gastric cancer

Although antiangiogenic therapy has been used in gastric cancer, disease progression due to drug resistance remains common. Neutrophils play an important role in the occurrence and progression of cancer via neutrophil extracellular traps (NETs). However, few studies have investigated angiogenic regulation in gastric cancer. We aimed to determine the role of NETs in promoting angiogenesis in gastric cancer. Multiple immunohistochemical staining was used to analyze the spatial distribution of NETs and microvessels in patient tissue samples. A mouse subcutaneous tumor model was established to determine the effect of NETs on tumor growth, and changes in microvessel density were observed via immunohistochemical staining. We screened differentially expressed proteins in HUVECs stimulated by NETs via proteomics. Cell Counting Kit-8, EdU labeling, and tubule formation assays were used to verify the effect of NETs on HUVEC proliferation, migration, and tubule formation. Blocking NETs, which was related to decreased microvessel density, significantly inhibited tumor growth in the murine subcutaneous tumor model. Compared with those of the control group, tumor volume and mass among mice in the inhibition group decreased by 61.3% and 77.9%, respectively. The NET-DNA receptor CCDC25 was expressed in HUVECs, providing a platform for NETs to promote HUVEC proliferation, migration, and tubulation. In an in vitro rat aortic explant model, NETs induced HUVEC proliferation, survival, and chemotaxis, which were not significantly different from those observed in the VEGF stimulation group. Our results confirm that NETs promote angiogenesis in gastric cancer, providing a theoretical basis for identifying new anti-vascular therapeutic targets. Video Abstract.

Immune Checkpoint Inhibitors, Small-Molecule Immunotherapies and the Emerging Role of Neutrophil Extracellular Traps in Therapeutic Strategies for Head and Neck Cancer

Immune checkpoint inhibitor (ICI) therapy has revolutionized the treatment of many cancer types, including head and neck cancers (HNC). When checkpoint and partner proteins bind, these send an "off" signal to T cells, which prevents the immune system from destroying tumor cells. However, in HNC, and indeed many other cancers, more people do not respond and/or suffer from toxic effects than those who do respond. Hence, newer, more effective approaches are needed. The challenge to durable therapy lies in a deeper understanding of the complex interactions between immune cells, tumor cells and the tumor microenvironment. This will help develop therapies that promote lasting tumorlysis by overcoming T-cell exhaustion. Here we explore the strengths and limitations of current ICI therapy in head and neck squamous cell carcinoma (HNSCC). We also review emerging small-molecule immunotherapies and the growing promise of neutrophil extracellular traps in controlling tumor progression and metastasis.

TLR4 inhibited autophagy by modulating PI3K/AKT/mTOR signaling pathway in Gastric cancer cell lines

Toll-like receptors (TLRs) are pattern recognition receptors found on both immune and cancerous cells. Gastric cancer (GC) cells/tissues have been shown to exhibit elevated levels of TLR4. Here, we examined the role of TLR4 on autophagy and proliferation in GC cells. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot (WB) were used to determine TLR4 levels at different stages of GC cells/tissues as well as the levels of autophagy-related proteins (ARPs) and determine the underlying signaling mechanism. Proliferation was assessed via the CCK-8 assay. The protein and mRNA levels of ARPs were elucidated, followed by estimating the involved signaling pathways. Our results demonstrated that the modulation of the PI3K/AKT/mTOR pathway resulted from autophagy inhibition/induction, which was induced by the overexpression and knockdown of TLR4. Thus, TLR4 played a vital role in GC progression.