The present review describes the mechanisms of NETosis and its role in myocardial ischemia-reperfusion injury (MIRI), focusing on the release of neutrophil extracellular traps (NETs) by activated neutrophils. NETs, composed of depolymerized chromatin and granule proteins, are crucial for pathogen entrapment, infection control and immune regulation. However, NET formation, linked to neutrophil death (NETosis), exacerbates MIRI by promoting inflammation and tissue damage. To address therapeutic strategies for NETosis in MIRI, several potential clinically significant approaches were explored, including peptidylarginine deaminase 4 inhibition, DNase therapy, antioxidants, inflammation modulation, and antithrombotic treatments, which not only provide novel diagnostic biomarkers and therapeutic targets in MIRI, but are also expected to improve patient prognosis and advance the development of personalised medicine.

Feline infectious peritonitis is a viral disease caused by feline coronavirus an enveloped virus with a single-stranded RNA genome that is approximately 30 kb long. Although FCoV generally causes mild symptoms, approximately 5% of cases progress to death in cats worldwide. FCoV shares certain virological features with severe acute respiratory syndrome coronavirus 2 that causes COVID-19, indicating that common therapeutic strategies may be applicable. GS-441524 the parent drug of remdesivir and a competitive inhibitor of nucleoside triphosphates in viral RNA synthesis is a well-known treatment for FIP. However, comparative transcriptome and gene ontology analyses of normal (Normal), FIP-diseased (FIPD), and FIP-recovered (FIPR) cats have not yet been conducted.

In this study, we compared the mRNA expression profiles of peripheral blood mononuclear cells from Normal, FIPD, and FIPR cats to identify immunological alterations. We identified 677 (FIPD/Normal) and 431 (FIPR/FIPD) differentially expressed genes with statistical significance. These data were input into the bioinformatics program. As a result, the analysis revealed statistically significant and contrasting patterns of canonical pathways of neutrophil degranulation and interleukin-8 (IL-8) signaling pathways. Additionally, we observed that kruppel-like factor 6 (KLF6) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) were upstream molecules of IL-8, promoting neutrophil activation and function.

This study identified immunological alterations in PBMCs of Normal, FIPD, and FIPR cats. KLF-6 and NF-κB were found to regulate IL-8-mediated neutrophil activation.

Inflammation contributes to myocardial injury in ST-elevation myocardial infarction (STEMI). Interleukin-6 receptor (IL-6R) inhibition has been shown to mitigate myocardial injury and reduce levels of the prothrombotic and inflammatory mediator, neutrophil extracellular traps (NETs). The enzyme peptidylarginine deiminase 4 (PAD4) is central in NET formation. We hypothesized that PAD4 links IL-6R activation and NET formation.

We conducted thrombus aspiration and peripheral blood sampling in 33 STEMI patients. In thrombi and leukocytes, we quantified the mRNA of IL-6, IL-6R, and PAD4. In peripheral blood, the protein levels of IL-6, IL-6R, PAD4, dsDNA, H3Cit, MPO-DNA, and troponin T were quantified.

In thrombi and circulating leukocytes, PAD4 mRNA was associated with IL-6R mRNA (thrombi: β = 0.34, 95% CI [0.16-0.53], p = 0.001, circulating leukocytes: β = 0.92, 95% CI [0.07-1.77], p = 0.036). There were no correlations between PAD4 and IL-6 in thrombi and leukocytes. The protein levels of IL-6R were associated with the NET marker H3Cit (rs = 0.40, p = 0.02). In thrombi, PAD4 mRNA was associated with high levels of troponin T (β = 1.15 95% CI [0.27-2.04], p = 0.013).

We demonstrate an association between PAD4, IL-6R, and troponin release in STEMI patients. Our findings indicate a PAD4-mediated connection between IL-6R and NET formation and highlight PAD4 as a potential treatment target for mitigating inflammation and myocardial injury in STEMI.

NETosis, the process through which neutrophils release neutrophil extracellular traps (NETs), has emerged as a crucial mechanism in host defense and the pathogenesis of autoimmune responses. During the SARS-CoV-2 pandemic, this process received significant attention due to the central role of neutrophil recruitment and activation in infection control. However, elevated neutrophil levels and dysregulated NET formation have been linked to coagulopathy and endothelial damage, correlating with disease severity and poor prognosis in COVID-19. Moreover, it is known that SARS-CoV-2 can induce persistent low-grade systemic inflammation, known as long COVID, although the underlying causes remain unclear. It has been increasingly acknowledged that excessive NETosis and NET generation contribute to further pathophysiological abnormalities following SARS-CoV-2 infection. This review provides an updated overview of the role of NETosis in autoimmune diseases, but also the relationship between COVID-19 and long COVID with autoimmunity (e.g., latent and overt autoimmunity, molecular mimicry, epitope spreading) and NETosis (e.g., immune responses, NET markers). Finally, we discuss potential therapeutic strategies targeting dysregulated NETosis to mitigate the severe complications of COVID-19 and long COVID.

Neutrophils, conventionally regarded as a homogeneous immune cell population, have emerged as a heterogeneous group of cells with distinct gene profiles and immune properties. Activated neutrophils release a spectrum of bioactive substances, including cytokines, chemokines, proteolytic enzymes, reactive oxygen species and neutrophil extracellular traps (NETs), which are composed of decondensed DNA and antimicrobial proteins. NETs have a pivotal role in innate immunity, including in preventing the ascent of uropathogenic bacteria into the kidneys, as they efficiently trap pathogenic microorganisms. However, although indispensable for defence against pathogens, NETs also pose risks of self-damage owing to their cytotoxicity, thrombogenicity and autoantigenicity. Accordingly, neutrophils and NETs have been implicated in the pathogenesis of various disorders that affect the kidneys, including acute kidney injury, vasculitis, systemic lupus erythematosus, thrombotic microangiopathy and in various aetiologies of chronic kidney disease. Pathological alterations in the glomerular vascular wall can promote the infiltration of neutrophils, which can cause tissue damage and inflammation through their interactions with kidney-resident cells, including mesangial cells and podocytes, leading to local cell death. Targeting neutrophil activation and NET formation might therefore represent a new therapeutic strategy for these conditions.

Neutrophil extracellular trap (NET) formation is a process known as NETosis and is a critical innate immune response mechanism that can become pathologically dysregulated in various inflammatory, autoimmune, infectious, and neoplastic diseases. Reactive oxygen species (ROS) play a central role in NETosis induction, making antioxidants a promising therapeutic approach. This review outlines the molecular mechanisms underlying NET formation and highlights three principal antioxidant-based inhibitory strategies: NADPH oxidase (NOX) inhibition, ROS scavenging, and myeloperoxidase (MPO) inhibition. Evidence supports the use of agents such as diphenylene iodonium (NOX inhibitor), N-acetylcysteine and glutathione (ROS scavengers), and thiocyanate (MPO inhibitor), which significantly reduce NETosis in vitro and in vivo. Moreover, natural compounds like resveratrol show pleiotropic effects by modulating neutrophil activation, ROS production, and protease activity. Combination therapies that enhance total antioxidant capacity are particularly effective, though their translation to clinical practice faces challenges such as stimulus specificity, bioavailability, and maintaining immune competence. Antioxidant-based therapies thus represent a promising avenue for targeted NETosis modulation. Future research should focus on improving delivery systems, identifying NET-specific biomarkers, and integrating antioxidants into broader immunomodulatory strategies.

Neutrophils, the most abundant white blood cells in human circulation, play a crucial role in innate immunity. One of their key defense mechanisms is the formation of neutrophil extracellular traps (NETs), web-like structures composed of chromatin and antimicrobial proteins that help capture and neutralize pathogens. While previous studies have identified a limited set of NET-associated proteins, the comprehensive proteomic landscape of NETs induced by different stimuli remains largely unexplored. In this study, we used data-independent acquisition mass spectrometry to analyze the proteomic composition of NETs induced by five distinct stimuli: β-glucan, lipopolysaccharide, polyinosinic-polycytidylic acid sodium, resiquimod, and severe fever with thrombocytopenia syndrome bunyavirus. Across all conditions, we identified 5,868 NET-associated proteins, revealing significant stimulus-dependent differences in protein composition. Notably, differentially expressed proteins were detected in each condition, highlighting unique proteomic signatures that may reflect distinct immune responses. This dataset offers key insights into the proteomic diversity of NETs and their role in immune regulation, providing a foundation for future research on NET-mediated immunity in infectious and inflammatory diseases.

Acute inflammation, characterized by a rapid influx of neutrophils, is a protective response that can lead to chronic inflammatory diseases when left unresolved. We previously showed that secretion of LTB4-containing exosomes via nuclear envelope-derived multivesicular bodies is required for effective neutrophil infiltration during inflammation. Here we report that the co-secretion of these exosomes with nuclear DNA facilitates the resolution of the neutrophil infiltrate in a mouse skin model of sterile inflammation. Activated neutrophils exhibit rapid and repetitive DNA secretion as they migrate directionally using a mechanism distinct from suicidal neutrophil extracellular trap release and cell death. Packaging of DNA in the lumen of nuclear envelope-multivesicular bodies is mediated by lamin B receptor and chromatin decondensation. These findings advance our understanding of neutrophil functions during inflammation and the physiological relevance of DNA secretion.

Thrombotic diseases remain the major cause of death and disability worldwide, and the contribution of inflammation is increasingly recognized. Thromboinflammation has been identified as a key pathomechanism, but an unsupervised map of immune-cell states, trajectories, and intercommunication at a single-cell level has been lacking. Here, we reveal innate leukocyte substates with prominent thrombolytic properties by employing single-cell omics measures on human stroke thrombi. Using in vivo and in vitro thrombosis models, we propose a pro-resolving monocyte-neutrophil axis, combining two properties: (1) NR4A1hi non-classical monocytes acquire a thrombolytic and neutrophil-chemoattractive phenotype, and (2) blood neutrophils are thereby continuously recruited to established thrombi through CXCL8-CXCR1 and CXCR2 and adopt a hypoxia-induced thrombus-resolving urokinase receptor (PLAUR)+ phenotype. This immunothrombolytic axis results in thrombus resolution. Together, with this immune landscape of thrombosis, we provide a valuable resource and introduce the concept of "immunothrombolysis" with broad mechanistic and translational implications at the crossroad of inflammation and thrombosis.

It has been thought that neutrophil extracellular traps (NETs) and thrombosis exacerbate COVID-19, but, on the other hand, NETs are an important player in innate immunity. The precise roles of NETs and thrombosis in the course of COVID-19 have not been fully elucidated.

The roles were investigated in the literature and a new theory was formulated. When neutrophils encounter SARS-CoV-2 in the lung tissue, they undergo NETosis and capture the virus. This capture is triggered by electrostatic interaction between histones in NETs and SARS-CoV-2; histones are highly positively charged, and viruses, including SARS-CoV-2, have a net negative charge under physiological pH. NETs that capture SARS-CoV-2 fall into alveolar capillaries through the collapsed endothelium to spare the lung tissue from the toxicity of NETs. NETs in the microvessels cause microthrombosis; positively charged histones induce the aggregation of negatively charged platelets, which leads to microthrombi. Microthrombi engulfing SARS-CoV-2 are consolidated into fibrin clots, which are eventually degraded by increased fibrinolysis and eliminated from the circulation.

This novel theory suggests that NETosis and microthrombosis are phenomena inevitably elicited in COVID-19, and in combination they are a system newly termed "NETombosis". Undegraded fibrin clots remaining in the microcirculation may be the cause of the sequelae, because they cause long-lasting circulatory failure in various organs.

Sepsis-induced cardiomyopathy is a reversible non-ischemic acute cardiac dysfunction associated with sepsis. It is strongly associated with an abnormal immune response. It emerges as a vital threat to public health owing to its high mortality rate. However, the exact pathogenesis requires further investigation. In recent years, NETosis and ferroptosis, which are novel modes of programmed cell death, have been identified and found to play important roles in sepsis-related organ damage. This article outlines the mechanisms of these two modes of cell death, discusses the role of neutrophil extracellular traps in myocardial injury and the importance of ferroptosis in sepsis-induced cardiomyopathy, and reviews the potential interconnection between these two types of programmed cell death in sepsis-induced cardiomyopathy.

During the acute phase (1-3 days) of cerebral infarction, neutrophils and macrophages accumulate at the infarction site, inducing inflammation and cerebral oedema. However, the role of neutrophils in oedema formation after ischaemic stroke remains unclear. This study examined neutrophil involvement in cerebral oedema using a transient middle cerebral artery occlusion (tMCAO) rat model, primary cultured neutrophils, and astrocytes. Brain specimens were stained with myeloperoxidase (MPO) and lymphocyte antigen 6 complexes, locus G (Ly6G), and the number of MPO+/Ly6G+ cells was counted. Neutrophil infiltration began in the leptomeninges at 3 h, reaching the ischaemic cortex by 6 h and the striatum by 24 h, peaking at 24-48 h before declining. Neutrophils attached to endothelial walls and infiltrated the brain parenchyma, correlating with oedema severity. Infiltrating neutrophils strongly expressed IL-1α and TNF in the ischaemic brain. Co-culturing LPS-activated neutrophils with astrocytes increased Aqp4 mRNA and protein expression, which was inhibited by IL-1RI and TNF antagonists. These findings suggest that activated neutrophils exacerbate cerebral oedema by inducing astrocytic AQP4 expression via IL-1α and TNF in peri-infarct and ischaemic core tissues.

The Glucocorticoid-induced posterior subcapsular cataracts (GIC) is a common complication of patients received glucocorticoid treatment in clinic. We find that dexamethasone (DEX) induces lens epithelial cells' ferroptosis. DEX treatment increases intracellular ferroptosis signatures in lens epithelial cell line in vitro as well as in rat lens in vivo. The inhibition of ferroptosis by liproxstatin-1 reduces the incidence of DEX-induced rat GIC. Experimental evidence and expression profiling showed that DEX induces ferroptosis through upregulating tetraspanin CD82- controlled P53 expression. DEX-activated glucocorticoid receptors directly bind to the CD82 promoter, driving its transcriptional upregulation. CD82 expression is upregulated in the anterior capsular epithelium of GIC patients as well as in the DEX-treated rat lens and caused the cell death of anterior capsule. DEX treatment and Overexpression of CD82 in cells recapitulated ferroptotic signatures through P53 activation and GPX4/SLC7A11 suppression. Taken together, GIC is closely associated with the upregulation of CD82-P53-GPX4/SLC7A11 axis-mediated ferroptosis.

Neutrophil extracellular traps (NETs) are web-like, bactericidal structures produced by neutrophils and are composed principally of extracellular DNA, histones, elastase, and myeloperoxidase, among other components. NET formation is an innate immune response that is beneficial for pathogen killing and clearance. However, excessive NET formation and clearance defects can lead to inflammation and induce damage to host organs. NETs are also implicated in the development of noninfectious inflammatory disorders, such as liver injury in chronic liver diseases. The liver parenchyma contains hepatocytes, liver sinusoidal endothelial cells, Kupffer cells, and hepatic stellate cells. Each of these cells possesses unique structures and functions, and their interactions with NETs result in pathophysiological changes contributing to liver injury. This review updates the findings related to the modes of action and molecular mechanisms by which NETs modulate the pathophysiology of various hepatic cells and potentiate liver injury. The article also reviews the roles of NETs in hepatic ischemia reperfusion injury, hepatocellular carcinoma pathogenesis, and cancer metastasis. Last, we examine data to determine whether NETs induce crosstalk among various hepatic cells during liver injury and to identify future research directions.

Neutrophil extracellular traps (NETs) and circulating cell-free DNA (cfDNA) are pivotal in driving excessive inflammation and organ damage during sepsis, with their levels correlating positively with sepsis severity in both patients and murine models. Despite the ability of deoxyribonuclease I (DNase I) to degrade NETs and cfDNA, its short half-life and rapid degradation limit its therapeutic effectiveness. To address this challenge, we developed a methyl-branched liposome fused with a red blood cell membrane for the systemic delivery of DNase I (DNase I/Rm-Lipo). The efficacy of DNase I/Rm-Lipo was evaluated in the stimulated immune cells and septic model. The data confirmed that DNase I/Rm-Lipo efficiently removed excess NETs and cfDNA in activated neutrophils. Following injection, DNase I/Rm-Lipo exhibited an extended circulation time, effectively suppressing neutrophil activation and regulating macrophage polarization to mitigate inflammation and prevent organ dysfunction in septic mice. These findings highlight the therapeutic potential of DNase I/Rm-Lipo as a promising candidate for sepsis management by targeting the degradation of NETs and cfDNA.

Traumatic brain injury (TBI) triggers a robust inflammatory response that is closely linked to worsened clinical outcomes. S100A8/A9, also known as calprotectin or myeloid-related protein-8/14 (MRP8/14), is an alarmin primarily secreted by activated neutrophils with potent pro-inflammatory property. In this study, we explored the roles of S100A8/A9 in modulating neuroinflammation and influencing TBI outcomes, delving into the underlying mechanisms. S100A8/A9-enriched neutrophils were present in the injured brain tissue of TBI patients, and elevated plasma levels of S100A8/A9 were correlated with poorer neurological function. Furthermore, using a TBI mouse model, we demonstrated that treatment with the selective S100A8/A9 inhibitor Paquinimod significantly mitigated neuroinflammation and neuronal death, thereby improving the prognosis of TBI mice. Mechanistically, we found that S100A8/A9, in conjunction with neutrophil activation and infiltration into the brain, enhances reactive oxygen species (ROS) production within neutrophils, accelerating PAD4-mediated neutrophil extracellular trap (NET) formation, which in turn exacerbates neuroinflammation. These findings suggest that S100A8/A9 amplifies neuroinflammatory responses by promoting NET formation in neutrophils. Inhibition of S100A8/A9 effectively attenuated NET-mediated neuroinflammation; however, when PAD4 was overexpressed in the brain using adenovirus, leading to an increased formation of NET in the brain, the anti-inflammatory effects of S100A8/A9 inhibition were markedly diminished. Further experiments with PAD4 knockout mice confirmed that the reduction of NETs could substantially alleviate S100A8/A9-driven neuroinflammation. Finally, we established that the suppression of NET formation by S100A8/A9 inhibition is primarily mediated through the AMPK/Nrf2/HO-1 signaling pathway. These findings underscore the critical pathological role of S100A8/A9 in TBI and emphasize the need for further exploration of S100A8/A9 inhibitor Paquinimod as a potential therapeutic strategy for TBI.

Bongkrekic acid (BKA), a less well-known foodborne toxin, has been implicated in numerous poisoning incidents. Recent studies suggest that BKA exerts an impact on the immune system, particularly on innate immunity. The release of neutrophil extracellular traps (NETs) is relatively a newly-discovered mechanism involving innate immunity. This study was designed to characterize and evaluate the effects of BKA on human NET formation. The co-localization of DNA, histones, and myeloperoxidase (MPO) was determined via immunostaining to confirm BKA-triggered NET formation in human neutrophils. NET quantification showed that NET formation induced by BKA was both time- and dose-dependent, and was associated with p38, ERK, PAD4 and P2X1 receptor. Moreover, immunostaining analysis observed that BKA triggered both NET formation and autophagy. Additionally, pharmacological experiments revealed that autophagy mediated BKA-triggered NET formation. Collectively, these insights offer a novel perspective on the effects of BKA exposure on host's innate immune response, and may shed new light on BKA poisoning. We call for further work to be conducted in this field to unravel the intricate mechanisms governing NET formation and autophagy in the context of BKA poisoning.

Sepsis is a common critical condition that can lead to multiple organ injury. Sepsis-induced acute respiratory distress syndrome (ARDS) is frequently an important cause of poor prognosis and is associated with high mortality rates, despite existing therapeutic interventions. Neutrophil infiltration and extracellular traps (NET) are implicated in acute lung injury (ALI) and ARDS following sepsis. As circulating neutrophils infiltrate infected tissues, they come into direct contact with vascular endothelial cells (ECs). Although the ability of NETs to induce endothelial damage is well established, the specific role of direct EC-neutrophil interactions in NET formation and lung injury during sepsis is not fully understood.

In this study, NET formation was assessed when neutrophils were co-culture with ECs or separated from them and stimulated with phorbol 12-myristate 13-acetate (PMA), lipopolysaccharide (LPS), lipoteichoic acid (LTA), or septic plasma.

We found that adhesion of neutrophils on ECs is critical in NET formation in response to LPS, LTA, or septic plasma in vitro. Blocking the macrophage-1 antigen (Mac-1) impeded NET formation, while inhibiting P-selectin glycoprotein ligand-1 (PSGL-1) or leukocyte function-associated antigen-1 (LFA-1) did not. This adhesion-dependent NET formation was reliant on the influx of extracellular calcium and peptidylarginine deiminase 4 (PAD4)-mediated citrullination of histone H3. However, Mac-1 blockade did not alter calcium influx. In a murine model of LPS-induced sepsis, Mac-1 blockade reduced NET release, lowered inflammatory cytokine levels, mitigated endothelial damage, and attenuated lung injury.

Our findings offer insights into the critical role of EC-neutrophil direct contact in NET formation during sepsis and propose Mac-1 as a potential therapeutic target.

Sepsis is a complex syndrome resulting from an aberrant host response to infection. A hallmark of sepsis is the failure of the immune system to restore balance, characterized by hyperinflammation or immunosuppression. However, the net effect of immune system imbalance and the clinical manifestations are highly heterogeneous among patients. In recent years, research interest has shifted from focusing on the pathogenicity of microorganisms to the molecular mechanisms of host responses which is also associated with biomarkers that can help early diagnose sepsis and guide treatment decisions. Despite significant advancements in medical science, sepsis remains a major challenge in healthcare, contributing to substantial morbidity and mortality worldwide. Further research is needed to improve our understanding of this condition and develop novel therapies to improve outcomes for patients with sepsis. This review explores the related signal pathways of sepsis and underscores recent advancements in understanding its mechanisms. Exploration of diverse biomarkers and the emerging concept of sepsis endotypes offer promising avenues for precision therapy in the future.

Under hyperglycemic conditions, impaired intestinal barrier integrity leads to heightened level of inflammation, playing important roles in driving diabetic complications. Emerging evidence supports the implications of neutrophil extracellular traps (NETs) in the pathogenesis of diabetes. However, whether NETs contribute to hyperglycemia-linked intestinal barrier impairment remains to be investigated. Moreover, baicalin, the major chemical component of Scutellaria baicalensis Georgi, is equipped with twofold intestinal protective and neutrophil suppressive activities. Yet, it is unclear if baicalin is effective at mitigating hyperglycemia-linked NETs-mediated intestinal barrier impairment.

To directly address the mechanistic implications of NETs in hyperglycemia-linked intestinal epithelial barrier impairment, the impact of DNase I treatment or Padi4 gene deficiency on intestinal epithelial integrity was first examined in the streptozotocin (STZ)-induced hyperglycemic mice in vivo. Next, the pharmacological impact of baicalin on NETs formation and intestinal epithelial barrier impairment was investigated in high glucose- and/or lipopolysaccharides (LPS)-stimulated neutrophils in vitro and in STZ-induced hyperglycemic mice in vivo, respectively.

The in vitro experiments confirmed that high glucose and/or LPS induced NETs formation. NETs directly impaired the viability and tight junction of the intestinal epithelial cells. The histological and immunohistochemical examinations unveiled that along with impaired intestinal epithelial morphology, citrullinated histone H3 (H3Cit), a marker of NETs, and neutrophil specific Ly6G were readily detected in the intestinal epithelium in the hyperglycemic mice. Without affecting the presence of neutrophils, DNase I treatment or Padi4 gene deficiency markedly mitigated intestinal NETs formation and improved the intestinal morphology in the hyperglycemic mice. Notably, baicalin suppressed NETs formation and inhibited histone H3 citrullination stimulated by high glucose, LPS or both in vitro. Furthermore, baicalin blunted NETs formation and partially preserved the integrity of the intestinal epithelium in the hyperglycemic mice in vivo.

The current study sheds new light on the pathophysiological implications of NETs in intestinal epithelial barrier impairment under hyperglycemic conditions. Most importantly, the findings here demonstrate for the first time that baicalin directly inhibits NETs formation stimulated by high glucose and/or LPS, which may in part account for its pharmacological effects at protecting against hyperglycemia-linked intestinal epithelial barrier impairment.

Neutrophils play a key role in inflammatory responses and thrombosis, but their complex interactions in disease pathogenesis are not fully understood. This review examines the multifaceted roles of neutrophils, focusing on their activation, cytokine release, and formation of neutrophil extracellular traps (NETs), which contribute to host defense and thrombosis. We discuss the interaction between inflammation and coagulation, the direct effect of neutrophils on thrombus stability, and their involvement in pathological thrombotic diseases. The therapeutic potential of neutrophil drug loading in the treatment of thrombosis, as well as the clinical implications and future research directions, are highlighted. The aim of this review is to gain insight into the critical neutrophil-inflammation-thrombus axis and its potential as a therapeutic target for thrombotic diseases and to suggest possible directions for neutrophil-loaded drug therapy for thrombosis.

Neutrophil extracellular traps (NETs) have received significant attention in recent years for their role in both the immune response and the vascular damage associated with inflammation. Platelets have been described as critical components of NETs since the initial description of this physio-pathological response of neutrophils. Platelets have been shown to play a dual role as responders and also as stimulators of NETs. The direct interaction with DNA leads to the entrapment of platelets into NETs, a phenomenon that significantly contributes to the thrombotic complications of inflammation and neutrophil activation, while the direct and paracrine stimulation of neutrophils by platelets has been shown to initiate the process of NET formation. In this review, we provide a comprehensive description of our current understanding of the molecular mechanisms underlying the entrapping of platelets into NETs and, in parallel, the platelet-driven cellular responses promoting NET formation. We then illustrate established examples of the contribution of NETs to vascular pathologies, describe the important questions that remain to be answered regarding the contribution of platelets to NET formation and NET-dependent cardiovascular complication, and highlight the fundamental steps taken towards the application of our understanding of platelets' contribution to NETs for the development of novel cardiovascular therapies.

Sepsis remains the leading cause of death in intensive care units. Despite newer antimicrobial and supportive therapies, specific treatments are still lacking. Neutrophils are pivotal components of the effector phase of the host immune defense against pathogens and play a crucial role in the control of infections under normal circumstances. In addition to its anti-infective effects, the dysregulation and overactivation of neutrophils may lead to severe inflammation or tissue damage and are potential mechanisms for poor prognosis in sepsis. This review focuses on recent advancements in the understanding of the functional status of neutrophils across various pathological stages of sepsis to explore the mechanisms by which neutrophils participate in sepsis progression and provide insights for the treatment of sepsis by targeting neutrophils.

Neutrophil extracellular traps (NETs) participate in both host defense and the pathogenesis of various diseases, such as infections, thrombosis, and tumors. While they help capture and eliminate pathogens, NETs' excessive or dysregulated formation can lead to tissue damage and disease progression. Therapeutic strategies targeting NET modulation have shown potential, but challenges remain, particularly in achieving precise drug delivery and maintaining drug stability. Nanoparticle (NP)-based drug delivery systems offer innovative solutions for overcoming the limitations of conventional therapies. This review explores the biological mechanisms of NET formation, their interactions with NPs, and the therapeutic applications of NP-based drug delivery systems for modulating NETs. We discuss how NPs can be designed to either promote or inhibit NET formation and provide a comprehensive analysis of their potential in treating NET-related diseases. Additionally, we address the current challenges and future prospects for NP-based therapies in NET research, aiming to bridge the gap between nanotechnology and NET modulation for the development of novel therapeutic approaches.

Neutrophils release neutrophil extracellular traps (NETs) as part of a healthy host immune response. NETs physically trap and kill pathogens as well as activating and facilitating crosstalk between immune cells and complement. Excessive or inadequately resolved NETs are implicated in the underlying pathophysiology of sepsis and other inflammatory diseases, including amplification of the inflammatory response and inducing thrombotic complications. Here, we review the growing evidence implicating neutrophils and NETs as central players in the dysregulated host immune response. We discuss potential strategies for modifying NETs to improve patient outcomes and the need for careful patient selection.

Neutrophils, as essential component of the innate immune response, form a crucial part in the defence mechanisms through the release of extracellular traps (NETs). These web-like structures, composed of chromatin and antimicrobial proteins, are essential for the entrapment and inactivation of pathogens. However, either constitutive formation or inefficient clearance of NETs leads to adverse effects such as fibrosis, thrombosis, delayed wound healing and tissue damage in multiple diseases associated with sterile inflammation. This dichotomy casts NETs as both protective agents and harmful factors in several diseases such as autoimmune diseases, metabolic syndromes, systemic infections, and malignancies. Besides microbes and their products, variety of stimulants including pro-inflammatory cytokines induce NETs. The complex interactions and cross talk among the pro-inflammatory cytokines including IL-8, IL-6, GM-CSF, TNF-α, IFNs, and IL-1β activate neutrophils to form NETs and also contributes to a vicious circle of inflammatory cascade, leading to increased inflammation, oxidative stress, and thrombotic events. Emerging evidence indicates that the dysregulated cytokine milieus in diseases, such as diabetes mellitus, obesity, atherosclerosis, stroke, rheumatoid arthritis, and systemic lupus erythematosus, potentiate NETs release, thereby promoting disease development. Thus, neutrophils represent both critical effectors and potential therapeutic targets, underscoring their importance in the context of cytokine-mediated therapies for a spectrum of diseases. In the present review, we describe various cytokines and associated signalling pathways activating NETs formation in different human pathologies. Further, the review identifies potential strategies to pharmacologically modulate cytokine pathways to reduce NETs.

Acute pancreatitis (AP) is one of the most common gastrointestinal emergencies, often resulting in self-digestion, edema, hemorrhage, and even necrosis of pancreatic tissue. When AP progresses to severe acute pancreatitis (SAP), it often causes multi-organ damage, leading to a high mortality rate. However, the molecular mechanisms underlying SAP-mediated organ damage remain unclear. This study aims to systematically mine SAP data from public databases and combine experimental validation to identify key molecules involved in multi-organ damage caused by SAP. Retrieve transcriptomic data of mice pancreatic tissue for AP, lung and liver tissue for SAP, and corresponding normal tissue from the Gene Expression Omnibus (GEO) database. Conduct gene differential analysis using Limma and DEseq2 methods. Perform enrichment analysis using the clusterProfiler package in R software. Score immune cells and immune status in various organs using single-sample gene set enrichment analysis (ssGSEA). Evaluate mRNA expression levels of core genes using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. Validate serum amylase, TNF-α, IL-1β, and IL-6 levels in peripheral blood using enzyme-linked immunosorbent assay (ELISA), and detect the formation of neutrophil extracellular traps (NETs) in mice pancreatic, liver, and lung tissues using immunofluorescence. Differential analysis reveals that 46 genes exhibit expression dysregulation in mice pancreatic tissue for AP, liver and lung tissue for SAP, as well as peripheral blood in humans. Functional enrichment analysis indicates that these genes are primarily associated with neutrophil-related biological processes. ROC curve analysis indicates that 12 neutrophil-related genes have diagnostic potential for SAP. Immune infiltration analysis reveals high neutrophil infiltration in various organs affected by SAP. Single-cell sequencing analysis shows that these genes are predominantly expressed in neutrophils and macrophages. FPR1, ITGAM, and C5AR1 are identified as key genes involved in the formation of NETs and activation of neutrophils. qPCR and IHC results demonstrate upregulation of FPR1, ITGAM, and C5AR1 expression in pancreatic, liver, and lung tissues of mice with SAP. Immunofluorescence staining shows increased levels of neutrophils and NETs in SAP mice. Inhibition of NETs formation can alleviate the severity of SAP as well as the levels of inflammation in the liver and lung tissues. This study identified key genes involved in the formation of NETs, namely FPR1, ITGAM, and C5AR1, which are upregulated during multi-organ damage in SAP. Inhibition of NETs release effectively reduces the systemic inflammatory response and liver-lung damage in SAP. This research provides new therapeutic targets for the multi-organ damage associated with SAP.

Acute myocardial infarction (AMI), primarily caused by coronary atherosclerosis, initiates a series of events that culminate in the obstruction of coronary arteries, resulting in severe myocardial ischemia and hypoxia. The subsequent myocardial ischemia/reperfusion (I/R) injury further aggravates cardiac damage, leading to a decline in heart function and the risk of life-threatening complications. The complex interplay of multiple regulated cell death (RCD) pathways plays a pivotal role in the pathogenesis of AMI. Each RCD pathway is orchestrated by a symphony of molecular regulatory mechanisms, highlighting the dynamic changes and critical roles of key effector molecules. Strategic disruption or inhibition of these molecular targets offers a tantalizing prospect for mitigating or even averting the onset of RCD, thereby limiting the extensive loss of cardiomyocytes and the progression of detrimental myocardial fibrosis. This review systematically summarizes the mechanisms underlying various forms of RCD, provides an in-depth exploration of the pathogenesis of AMI through the lens of RCD, and highlights a range of promising therapeutic targets that hold the potential to revolutionize the management of AMI.

Exercising regularly promotes health, but these benefits are complicated by acute inflammation induced by exercise. A potential source of inflammation is cell-free DNA (cfDNA), yet the cellular origins, molecular causes, and immune system interactions of exercise-induced cfDNA are unclear. To study these, 10 healthy individuals were randomized to a 12-wk exercise program of either high-intensity tactical training (HITT) or traditional moderate-intensity training (TRAD). Blood plasma was collected pre- and postexercise at weeks 0 and 12 and after 4 wk of detraining upon program completion. Whole-genome enzymatic methylation sequencing (EM-seq) with cell-type proportion deconvolution was applied to cfDNA obtained from the 50 plasma samples and paired to concentration measurements for 90 circulating cytokines. Acute exercise increased the release of cfDNA from neutrophils, dendritic cells (DCs), and macrophages proportional to exercise intensity. Exercise training reduced cfDNA released in HITT participants but not TRAD and from DCs and macrophages but not neutrophils. For most participants, training lowered mitochondrial cfDNA at rest, even after detraining. Using a sequencing analysis approach we developed, we concluded that rapid ETosis, a process of cell death where cells release DNA extracellular traps, was the likely source of cfDNA, demonstrated by enrichment of nuclear DNA. Further, several cytokines were induced by acute exercise, such as IL-6, IL-10, and IL-16, and training attenuated the induction of only IL-6 and IL-17F. Cytokine levels were not associated with cfDNA induction, suggesting that these cytokines are not the main cause of exercise-induced cfDNA. Overall, exercise intensity and training modulated cfDNA release and cytokine responses, contributing to the anti-inflammatory effects of regular exercise.

The global pandemic of obesity poses a serious health, social, and economic burden. Patients living with obesity are at an increased risk of developing noncommunicable diseases or to die prematurely. Obesity is a state of chronic low-grade inflammation. Neutrophils are first to be recruited to sites of inflammation, where they contribute to host defense via phagocytosis, degranulation, and extrusion of neutrophil extracellular traps (NETs). NETs are web-like DNA structures of nuclear or mitochondrial DNA associated with cytosolic antimicrobial proteins. The primary function of NETosis is preventing the dissemination of pathogens. However, neutrophils may occasionally misidentify host molecules as danger-associated molecular patterns, triggering NET formation. This can lead to further recruitment of neutrophils, resulting in propagation and a vicious cycle of persistent systemic inflammation. This scenario may occur when neutrophils infiltrate expanded obese adipose tissue. Thus, NETosis is implicated in the pathophysiology of autoimmune and metabolic disorders, including obesity. This review explores the role of NETosis in obesity and two obesity-associated conditions-hypertension and liver steatosis. With the rising prevalence of obesity driving research into its pathophysiology, particularly through diet-induced obesity models in rodents, we discuss insights gained from both human and animal studies. Additionally, we highlight the potential offered by rodent models and the opportunities presented by genetically modified mouse strains for advancing our understanding of obesity-related inflammation.

Neutrophil extracellular traps (NETs) are large structures composed of chromatin, histones and granule-derived proteins released extracellularly by neutrophils. They are generally considered to be a part of the antimicrobial defense strategy, preventing the dissemination of pathogens. However, overproduction of NETs or their ineffective clearance can drive various pathologies, many of which are associated with advanced age and involve uncontrolled inflammation, oxidative, cardiovascular and neurodegenerative stress as underlying mechanisms. Targeting NETs in the elderly as an anti-aging therapy seems to be a very attractive therapeutic approach. Therapeutic apheresis with a specific filter to remove NETs could be a promising strategy worth considering.

The field of osteoimmunology has primarily focused on fracture healing in isolated musculoskeletal injuries. The innate immune system is the initial response to fracture, with inflammatory macrophages, cytokines, and neutrophils arriving first at the fracture hematoma, followed by an anti-inflammatory phase to begin the process of new bone formation. This review aims to first discuss the current literature and knowledge gaps on the immune responses governing single fracture healing by encompassing the individual role of macrophages, neutrophils, cytokines, mesenchymal stem cells, bone cells, and other immune cells. This paper discusses the interactive effects of these cellular responses underscoring the field of osteoimmunology. The critical role of the metabolic environment in guiding the immune system properties will be highlighted along with some effective therapeutics for fracture healing in the context of osteoimmunology. However, compared to isolated fractures, which frequently heal well, long bone fractures in over 30 % of polytrauma patients exhibit impaired healing. Clinical evidence suggests there may be distinct physiologic and inflammatory pathways altered in polytrauma resulting in nonunion. Nonunion is associated with worse patient outcomes and increased societal healthcare costs. The dysregulated immunomodulatory/inflammatory response seen in polytrauma may lead to this increased nonunion rate. This paper will investigate the differences in immune response between isolated and polytrauma fractures. Finally, future directions for fracture studies are explored with consideration of the emerging roles of newly discovered immune cell functions in fracture healing, the existing challenges and conflicting results in the field, the translational potential of these studies in clinic, and the more complex nature of polytrauma fractures that can alter cell functions in different tissues.

A heightened risk for thrombosis is a hallmark of COVID-19. Expansive clinical experience and medical literature have characterized small (micro) and large (macro) vessel involvement of the venous and arterial circulatory systems. Most events occur in patients with serious or critical illness in the hyperacute (first 1-2 weeks) or acute phases (2-4 weeks) of SARS-CoV-2 infection. However, thrombosis involving the venous, arterial, and microcirculatory systems has been reported in the subacute (4-8 weeks), convalescent (> 8-12 weeks) and chronic phases (> 12 weeks) among patients with mild-to-moderate illness. The purpose of the current focused review is to highlight the distinguishing clinical features, pathological components, and potential mechanisms of venous, arterial, and microvascular thrombosis in patients with COVID-19. The overarching objective is to better understand the proclivity for thrombosis, laying a solid foundation for screening and surveillance modalities, preventive strategies, and optimal patient management.

Neutrophil extracellular traps (NETs) have been shown to exhibit chemotactic effects on circulating tumor cells at metastatic sites, promoting the progression of colorectal cancer liver metastasis (CRLM). However, the origin and factors contributing to the formation of NETs (NETosis) in the pre-metastatic niche (PMN) of target organs remain unclear. In this study, we investigated the relationship between phosphatase of regenerating liver-3 (PRL-3), myeloid-derived suppressor cells (MDSCs), neutrophils, and NETs through a retrospective clinical cohort study and a mouse model of CRLM. Our clinical findings revealed associations between PRL-3 expression and the infiltration of neutrophils and MDSCs in CRLM patients. Moreover, NETosis emerged as a robust indicator of poor prognosis for overall survival in these patients. In CRLM models, PRL-3 overexpression enhanced both primary tumor growth and liver metastasis. We found that the first week after tumor cell implantation appeared to be a crucial period for PMN formation, with notable infiltration of neutrophils, MDSCs, and NETosis during this time. Notably, co-culturing neutrophils with MDSCs induced NETosis in vitro, particularly with granulocyte-like MDSCs (Gr-MDSCs), the predominant subtype of infiltrating MDSCs. In summary, our findings elucidate the likely origin of NETs in the PMN during CRLM development and underscore the significant influence of PRL-3. These findings may offer potential immunotherapeutic targets for patients at risk of developing CRLM, warranting further investigation in clinical settings.

Obesity is a chronic, multifactorial disease characterized by persistent low-grade tissue and systemic inflammation. Fat accumulation in adipose tissue (AT) leads to stress and dysfunctional adipocytes, along with the infiltration of immune cells, which initiates and sustains inflammation. Neutrophils are the first immune cells to infiltrate AT during high-fat diet (HFD)-induced obesity. Emerging evidence suggests that the formation and release of neutrophil extracellular traps (NETs) play a significant role in the progression of obesity and related diseases. Additionally, obesity is associated with an imbalance in gut microbiota and increased intestinal barrier permeability, resulting in the translocation of live bacteria, bacterial deoxyribonucleic acid (DNA), lipopolysaccharides (LPS), and pro-inflammatory cytokines into the bloodstream and AT, thereby contributing to metabolic inflammation. Recent research has also shown that short-chain fatty acids (SCFAs), produced by gut microbiota, can influence various functions of neutrophils, including their activation, migration, and the generation of inflammatory mediators. This review comprehensively summarizes recent advancements in understanding the role of neutrophils and NET formation in the pathophysiology of obesity and related disorders while also focusing on updated potential therapeutic approaches targeting NETs based on studies conducted in humans and animal models.

Animal genomes are packaged into chromatin, a highly dynamic macromolecular structure of DNA and histone proteins organised into nucleosomes. This accommodates packaging of lengthy genomic sequences within the physical confines of the nucleus while also enabling precise regulation of access to genetic information. However, histones existed before chromatin and have lesser-known functions beyond genome regulation. Most notably, histones are potent antimicrobial agents, and the release of chromatin to the extracellular space is a defence mechanism nearly as ancient and widespread as chromatin itself. Histone sequences have changed very little throughout evolution, suggesting the possibility that some of their 'non-canonical' functions are at play in parallel or in concert with their genome regulatory functions. In this Review, we take an evolutionary perspective of histone, nuclear chromatin and extracellular chromatin biology and describe the known extranuclear and extracellular functions of histones. We detail molecular mechanisms of chromatin release and extracellular chromatin sensing, and we discuss their roles in physiology and disease. Finally, we present evidence and give a perspective on the potential of extracellular histones to act as bioactive, cell modulatory factors.

Idiopathic inflammatory myopathies (IIM) are a group of systemic autoimmune diseases characterized by muscle weakness and elevated serum creatine kinase levels. Recent research has highlighted the role of the innate immune system, particularly inflammasomes, in the pathogenesis of IIM. This review focuses on the role of inflammasomes, specifically NLRP3 and AIM2, and their associated proteins in the development of IIM. We discuss the molecular mechanisms of pyroptosis, a programmed cell death pathway that triggers inflammation, and its association with IIM. The NLRP3 inflammasome, in particular, has been implicated in muscle fiber necrosis and the subsequent release of damage-associated molecular patterns (DAMPs), leading to inflammation. We also explore the potential therapeutic implications of targeting the NLRP3 inflammasome with inhibitors such as glyburide and MCC950, which have shown promise in reducing inflammation and improving muscle function in preclinical models. Additionally, we discuss the role of caspases, particularly caspase-1, in the canonical pyroptotic pathway associated with IIM. The understanding of these mechanisms offers new avenues for therapeutic intervention and a better comprehension of IIM pathophysiology.