Neutrophil Extracellular Traps and Cardiovascular Diseases: An Update

Heart-brain axis in health and disease: role of innate and adaptive immunity

The importance of the brain-heart interaction has been increasingly recognized as a critical physiological axis that is altered in disease. In this review, we explore the intricate relationship between the central nervous system and cardiovascular health, focusing particularly on immunological mechanisms that influence the course of both neurological and cardiovascular diseases. While previous studies have established a key role of the autonomic nervous system (ANS) in linking brain and the heart, more recent studies have expanded our understanding of the multifaceted inter-organ interactions. As such, circulating mediators include immune cells of the adaptive and innate immune system and their secreted immunogenic factors have come into the focus as mediators along this bidirectional communication. Hence, in this review we briefly discuss the contribution of the ANS and then focus on innate and adaptive immune mechanisms along the heart-to-brain and brain-to-heart axes, illustrating how cardiovascular diseases affect cognitive functions and how brain pathologies lead to cardiac complications.

Intestinal neutrophil extracellular traps promote gut barrier damage exacerbating endotoxaemia, systemic inflammation and progression of diabetic retinopathy in type 2 diabetes

AIMS/HYPOTHESIS

Within the small intestine, neutrophils play an integral role in preventing bacterial infection. Upon interaction with bacteria or bacteria-derived antigens, neutrophils initiate a multi-staged response of which the terminal stage is NETosis, formation of protease-decorated nuclear DNA into extracellular traps. NETosis has a great propensity to elicit ocular damage and has been associated with diabetic retinopathy and diabetic macular oedema (DME) progression. Here, we interrogate the relationship between gut barrier dysfunction, endotoxaemia and systemic and intestinal neutrophilia in diabetic retinopathy.

METHODS

In a cohort of individuals with type 2 diabetes (n=58) with varying severity of diabetic retinopathy and DME, we characterised the abundance of circulating neutrophils by flow cytometry and markers of gut permeability and endotoxaemia by plasma ELISA. In a mouse model of type 2 diabetes, we examined the effects of diabetes on abundance and function of intestinal, blood and bone marrow neutrophils, gut barrier integrity, endotoxaemia and diabetic retinopathy severity. Pharmacological inhibition of NETosis was achieved by i.p. injection of the peptidyl arginine deiminase 4 inhibitor (PAD4i) GSK484 daily for 4 weeks between 6 and 7 months of type 2 diabetes.

RESULTS

In human participants, neutrophilia was unique to individuals with type 2 diabetes with diabetic retinopathy and DME and was accompanied by heightened circulating markers of gut permeability. At late-stage diabetes, neutrophilia and gut barrier dysfunction were seen in db/db mice. The db/db mice exhibited an increase in stem-like pre-neutrophils in the intestine and bone marrow and a decrease in haematopoietic vascular reparative cells. In the db/db mouse intestine, enhanced loss of gut barrier integrity was associated with elevated intestinal NETosis. Inhibition of NETosis by the PAD4i GSK484 resulted in decreased abundance of premature neutrophils in the intestine and blood and resulted in neutrophil retention in the bone marrow compared with vehicle-treated db/db mice. Additionally, the PAD4i decreased senescence within the gut epithelium and yielded a slowing of diabetic retinopathy progression.

CONCLUSIONS/INTERPRETATION

Severity of diabetic retinopathy and DME were associated with peripheral neutrophilia, gut barrier dysfunction and endotoxaemia in the human participants. db/db mice exhibited intestinal neutrophilia, specifically stem-like pre-neutrophils, which was associated with elevated NETosis and decreased levels of vascular reparative cells. Chronic inhibition of NETosis in db/db mice reduced intestinal senescence and NETs in the retina. These changes were associated with reduced endotoxaemia and an anti-inflammatory bone marrow milieu with retention of pre-neutrophils in the bone marrow and increased gut infiltration of myeloid angiogenic cells. Collectively, PAD-4i treatment decreased gut barrier dysfunction, restoring physiological haematopoiesis and levels of haematopoietic vascular reparative cells.

Neutrophils in Type 1 Diabetes: Untangling the Intricate Web of Pathways and Hypothesis

Neutrophils are increasingly recognized as key contributors to the pathogenesis of Type 1 Diabetes (T1D), yet their precise mechanistic role in disease onset and progression remains incompletely understood. While these innate immune cells reside in pancreatic tissue and support tissue homeostasis under physiological conditions, they can also drive tissue damage by triggering innate immune responses and modulating inflammation. Within the inflammatory milieu, neutrophils establish complex, bidirectional interactions with various immune cells, including macrophages, dendritic cells, natural killer cells, and lymphocytes. Once activated, they may enhance the innate immune response through direct or indirect crosstalk with immune cells, antigen presentation, and β-cell destruction or dysfunction. These mechanisms underscore the multifaceted and dynamic role of neutrophils in T1D, shaped by their intricate immunological interactions. Further research into the diverse functional capabilities of neutrophils is crucial for uncovering novel aspects of their involvement in T1D, potentially revealing new therapeutic targets to modulate disease progression.

Neutrophils in Atopic Dermatitis

Neutrophils have a critical role in inflammation. Recent studies have identified their distinctive presence in certain types of atopic dermatitis (AD), yet their exact function remains unclear. This review aims to compile studies elucidating the role of neutrophils in AD pathophysiology. Proteins released by neutrophils, including myeloperoxidase, elastase, and lipocalin, contribute to pruritus progression in AD. Neutrophilic oxidative stress and the formation of neutrophil extracellular traps may further worsen AD. Elevated neutrophil elastase and high-mobility group box 1 protein expression in AD patients' skin exacerbates epidermal barrier defects. Neutrophil-mast cell interactions in allergic inflammation steer the immunological response toward Th2 imbalance and activate the Th17 pathway, particularly in response to allergens or infections linked to AD. Notably, drugs alleviating pruritic symptoms in AD inhibit neutrophilic inflammation. In conclusion, these findings underscore that neutrophils may be therapeutic targets for AD symptoms, emphasizing their inclusion in AD treatment strategies.

Thromboinflammation is associated with clinical outcome after ST-elevation myocardial infarction

ABSTRACT

Platelets are crucial in thrombus formation during ST-elevation myocardial infarction (STEMI). In addition, they also play an important role in postischemic thromboinflammation, which is determined by the interplay between activated platelets and neutrophils. The latter form neutrophil extracellular traps, which are detectable in plasma as citrullinated histone H3-deoxyribonucleic acid-DNA complexes. Prediction of the risk of recurrent events is important in precision medicine. Therefore, we investigated whether circulating thromboinflammatory markers predict clinical outcome after STEMI. We performed a prospective, multicentric, observational, all-comer study of patients with STEMI (n = 361). Thromboinflammation, measured as H3Cit-DNA complexes, was assessed on day 1 after presentation with STEMI as well as 5 days and 6 months after STEMI by enzyme-linked immunosorbent assay. Twelve months of clinical follow-up was conducted. Multivariate analysis was performed investigating which variables were independently associated with major adverse cardiac events (MACEs). Patients were aged 64 ± 12 years; 80% were male; and 40% had diabetes mellitus. Thromboinflammation was enhanced during index hospitalization compared with 6-months follow-up (137.4 ± 100.0 μg/L vs 53.7 ± 54.7 μg/L; P < .001). Additionally, patients within the highest tertile of thromboinflammation at day 1 after STEMI showed worse outcome during follow-up (hazard ratio, 2.57; 95% confidence interval, 1.72-3.85; P < .001). Receiver operating characteristic analysis revealed a cutoff value of 219.3 μg/L. In multivariate logistic regression analysis, thromboinflammation was independently associated with outcome after STEMI. To sum it up, thromboinflammation is enhanced in STEMI. It identifies patients at high risk of MACE. Therefore, thromboinflammation might be a promising target and marker in precision medicine. The trial was registered at www.clinicaltrials.gov as #NCT03539133.

Nucleic acid liquid biopsies in cardiovascular disease: Cell-free DNA liquid biopsies in cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of death worldwide, and despite treatment efforts, cardiovascular function cannot always be restored, and progression of disease be prevented. Critical insights are oftentimes based on tissue samples. Current knowledge of tissue pathology typically relies on invasive biopsies or postmortem samples. Liquid biopsies, which assess circulating mediators to deduce the histology and pathology of distant tissues, have been advancing rapidly in cancer research and offer a promising approach to be translated to the understanding and treatment of CVD. The widely understood elevations in cell-free DNA during acute and chronic cardiovascular conditions, associate with disease, severity, and offer prognostic value. The role of neutrophil extracellular traps (NETs) and circulating nucleases in thrombosis provide a solid rationale for liquid biopsies in CVD. cfDNA originates from various tissue types and cellular sources, including mitochondria and nuclei, and can be used to trace cell and tissue type lineage, as well as to gain insight into the activation status of cells. This article discusses the origin, structure, and potential utility of cfDNA, offering a deeper and less invasive approach for the understanding of the complexities of CVD.

Targeting neutrophils extracellular traps, a promising anti-thrombotic therapy for natural products from traditional Chinese herbal medicine

Thrombi are the main cause of vascular occlusion and contribute significantly to cardiovascular events and death. Neutrophils extracellular traps (NETs)-induced thrombosis plays a vital role in thrombotic complications and it takes the main responsibility for the resistance of fibrinolysis. However, the conventional anti-thrombotic therapies are inadequate to treat NETs-induced thrombotic complications but carry a high risk of bleeding. Consequently, increased attention has shifted towards exploring novel anti-thrombotic treatments targeting NETs. Interestingly, accumulating evidences prove that natural products from traditional Chinese herbal medicines have a great potential to mitigate thrombosis through inhibiting generous NETs formation and degrading excessive NETs. In this review, we elaborated the formation and degradation of NETs and highlighted its pivotal role in immunothrombosis through interactions with platelets and coagulation factors. Since available anti-thrombotic drugs targeting NETs are deficient, we further summarized the natural products and compounds from traditional Chinese herbal medicines which exert effective actions on regulating NETs formation and also have anti-thrombotic effects. Our findings underscore the diverse effects of natural products in targeting NETs, including relieving inflammation and oxidative stress of neutrophils, inhibiting neutrophils activation and DNA efflux, suppressing granule proteins release, reducing histones and promoting DNA degradation. This review aims to highlight the significance of natural medicines in anti-thrombotic therapies through targeting NETs and to lay a groundwork for developing novel anti-thrombotic agents from traditional Chinese herbal medicines.

Colchicine prevents perioperative myocardial injury in cardiac surgery by inhibiting the formation of neutrophil extracellular traps: evidence from rat models

OBJECTIVES

Colchicine, an anti-inflammatory agent, has been reported to improve myocardial infarction prognosis by inhibiting neutrophil extracellular traps (NETs) release. However, its role in cardiac surgery and the mechanisms behind NETs suppression remain unclear. This study aimed to explore colchicine's cardioprotective effects against perioperative myocardial injury in cardiac surgery, focusing on NETs inhibition as a novel therapeutic strategy.

METHODS

Male Sprague-Dawley rats were pre-treated with colchicine (0.1 mg/kg/day) or CI-amidine (10 mg/kg/day) for 7 days before undergoing cardiopulmonary bypass and myocardial ischaemia/reperfusion injury. The model was created by subjecting the rats to cardiopulmonary bypass and myocardial ischaemia/reperfusion injury. Under 4.0% sevoflurane anaesthesia, cardiopulmonary bypass was initiated by cannulating the tail artery and right atrium, and perfusion was maintained for 4 h. Immunofluorescence detected NETs, and haematoxylin and eosin staining assessed inflammatory cell.

RESULTS

We found colchicine treatment significantly reduced perioperative myocardial injury in rats. Furthermore, we observed a notable elevation of NETs in the myocardial tissue of animal models. Moreover, suppressing peptidylarginine deiminase 4 was found to markedly diminish perioperative myocardial injury in rats. Additionally, colchicine can mitigate the release of NETs by inhibiting peptidylarginine deiminase 4.

CONCLUSIONS

NETs were significantly elevated during the perioperative period of cardiac surgery. Colchicine significantly mitigated myocardial injury in cardiac surgery by inhibiting NETs formation, with peptidylarginine deiminase 4 inhibition being one of its mechanisms.

The web of intrigue: unraveling the role of NETosis within the gut-microbiome-immune-heart axis in acute myocardial infarction and heart failure

This review summarizes the role of NETosis, or the release of neutrophil extracellular traps (NETs), and its interplay with the gut microbiome in acute myocardial infarction (AMI) and heart failure. NETosis contributes to inflammation, thrombosis, and atherothrombosis, all central to the pathophysiology of AMI and heart failure. NETosis can be activated by inflammation and dietary factors, indicating association with metabolic conditions. In cases of heart failure, NETosis is regulated by inflammatory molecules such as C-reactive protein (CRP), and Krüppel-like factor 2 (KLF2) - a protein that plays a role in controlling inflammation, and angiotensin II. Changes in the gut microbiome are linked to the severity and recovery of cardiac injury post-AMI and heart failure progression. The microbiome's influence extends to immune modulation and inflammatory responses, potentially affecting NETosis.

Pathophysiology in Brain Arteriovenous Malformations: Focus on Endothelial Dysfunctions and Endothelial-to-Mesenchymal Transition

Brain arteriovenous malformations (bAVMs) substantially increase the risk for intracerebral hemorrhage (ICH), which is associated with significant morbidity and mortality. However, the treatment options for bAVMs are severely limited, primarily relying on invasive methods that carry their own risks for intraoperative hemorrhage or even death. Currently, there are no pharmaceutical agents shown to treat this condition, primarily due to a poor understanding of bAVM pathophysiology. For the last decade, bAVM research has made significant advances, including the identification of novel genetic mutations and relevant signaling in bAVM development. However, bAVM pathophysiology is still largely unclear. Further investigation is required to understand the detailed cellular and molecular mechanisms involved, which will enable the development of safer and more effective treatment options. Endothelial cells (ECs), the cells that line the vascular lumen, are integral to the pathogenesis of bAVMs. Understanding the fundamental role of ECs in pathological conditions is crucial to unraveling bAVM pathophysiology. This review focuses on the current knowledge of bAVM-relevant signaling pathways and dysfunctions in ECs, particularly the endothelial-to-mesenchymal transition (EndMT).

Neutrophil extracellular traps mediate neuro-immunothrombosis

Neutrophil extracellular traps are primarily composed of DNA and histones and are released by neutrophils to promote inflammation and thrombosis when stimulated by various inflammatory reactions. Neutrophil extracellular trap formation occurs through lytic and non-lytic pathways that can be further classified by formation mechanisms. Histones, von Willebrand factor, fibrin, and many other factors participate in the interplay between inflammation and thrombosis. Neuro-immunothrombosis summarizes the intricate interplay between inflammation and thrombosis during neural development and the pathogenesis of neurological diseases, providing cutting-edge insights into post-neurotrauma thrombotic events. The blood-brain barrier defends the brain and spinal cord against external assaults, and neutrophil extracellular trap involvement in blood-brain barrier disruption and immunothrombosis contributes substantially to secondary injuries in neurological diseases. Further research is needed to understand how neutrophil extracellular traps promote blood-brain barrier disruption and immunothrombosis, but recent studies have demonstrated that neutrophil extracellular traps play a crucial role in immunothrombosis, and identified modulators of neuro-immunothrombosis. However, these neurological diseases occur in blood vessels, and the mechanisms are unclear by which neutrophil extracellular traps penetrate the blood-brain barrier to participate in immunothrombosis in traumatic brain injury. This review discusses the role of neutrophil extracellular traps in neuro-immunothrombosis and explores potential therapeutic interventions to modulate neutrophil extracellular traps that may reduce immunothrombosis and improve traumatic brain injury outcomes.

IL-1 signaling pathway, an important target for inflammation surrounding in myocardial infarction

Acute myocardial infarction is an important cardiovascular disease worldwide. Although the mortality rate of myocardial infarction (MI) has improved dramatically in recent years due to timely treatment, adverse remodeling of the left ventricle continues to affect cardiac function. Various immune cells are involved in this process to induce inflammation and amplification. The infiltration of inflammatory cells in the infarcted myocardium is induced by various cytokines and chemokines, and the recruitment of leukocytes further amplifies the inflammatory response. As an increasing number of clinical anti-inflammatory therapies have achieved significant success in recent years, treating myocardial infarction by targeting inflammation may become a novel therapeutic option. In particular, successful clinical trials of canakinumab have demonstrated the important role of the inflammatory factor interleukin-1 (IL-1) in atherosclerosis. Targeted IL-1 therapy may decrease inflammation levels and improve cardiac function in patients after myocardial infarction. This article reviews the complex series of responses after myocardial infarction, including the involvement of inflammatory cells and the role of cytokines and chemokines, focusing on the progression of the IL-1 family in myocardial infarction as well as the performance of current targeted therapy drugs in experiments.

Inflammation-, immunothrombosis,- and autoimmune-feedback loops may lead to persistent neutrophil self-stimulation in long COVID

Understanding the pathophysiology of long COVID is one of the most intriguing challenges confronting contemporary medicine. Despite observations recently made in the relevant molecular, cellular, and physiological domains, it is still difficult to say whether the post-acute sequelae of COVID-19 directly correspond to the consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This work hypothesizes that neutrophils and neutrophil extracellular traps (NETs) production are at the interconnection of three positive feedback loops which are initiated in the acute phase of SARS-CoV-2 infection, and which involve inflammation, immunothrombosis, and autoimmunity. This phenomenon could be favored by the fact that SARS-CoV-2 may directly bind and penetrate neutrophils. The ensuing strong neutrophil stimulation leads to a progressive amplification of an exacerbated and uncontrolled NETs production, potentially persisting for months beyond the acute phase of infection. This continuous self-stimulation of neutrophils leads, in turn, to systemic inflammation, micro-thromboses, and the production of autoantibodies, whose significant consequences include the persistence of endothelial and multiorgan damage, and vascular complications.

Neutrophil NLRP3 promotes cardiac injury following acute myocardial infarction through IL-1β production, VWF release and NET deposition in the myocardium

NLRP3 inflammasome has been implicated in neutrophil polarization and extrusion of neutrophil extracellular traps (NETs) in vitro and facilitates secretion of Il1-beta (IL-1β). Permanent ligation of the left anterior descending artery was used to induce MI in WT and NLRP3-/- mice as well as in NLRP3-/- recipient mice transfused with either WT or NLRP3-/- neutrophils. NLRP3 deficiency reduced infarct size to roughly a third of WT heart injury and preserved left ventricular (LV) function at 12 h after MI as assessed by echocardiography and triphenyltetrazolium chloride staining of live tissue. Transfusion of WT but not NLRP3-/- neutrophils after MI increased infarct size in NLRP3-/- mice and significantly reduced LV function. The key features of myocardial tissue in WT neutrophil transfused recipients were increased H3Cit-positive deposits with NET-like morphology and increased tissue levels of IL-1β and plasma levels of von Willebrand Factor (VWF). Flow cytometry analysis also revealed that neutrophil NLRP3 increased the number of labeled and transfused neutrophils in the bone marrow of recipient mice following MI. Our data suggest a key role for neutrophil NLRP3 in the production of IL-1β and deposition of NETs in cardiac tissue exacerbating injury following MI. We provide evidence for a link between neutrophil NLRP3 and VWF release likely enhancing thromboinflammation in the heart. Neutrophil NLRP3 deficiency conferred similar cardioprotective effects to general NLRP3 deletion in MI rendering anti-neutrophil NLRP3 therapy a promising target for early cardioprotective treatment.

LL37/FPR2 regulates neutrophil mPTP promoting the development of neutrophil extracellular traps in diabetic retinopathy

Diabetic retinopathy (DR) is characterized by chronic, low-grade inflammation. This state may be related to the heightened production of neutrophil extracellular traps (NETs) induced by high glucose (HG). Human cathelicidin antimicrobial peptide (LL37) is an endogenous ligand of G protein-coupled chemoattractant receptor formyl peptide receptor 2 (FPR2), expressed on neutrophils and facilitating the formation and stabilization of the structure of NETs. In this study, we detected neutrophils cultured under different conditions, the retinal tissue of diabetic mice, and fibrovascular epiretinal membranes (FVM) samples of patients with proliferative diabetic retinopathy (PDR) to explore the regulating effect of LL37/FPR2 on neutrophil in the development of NETs during the process of DR. Specifically, HG or NG with LL37 upregulates the expression of FPR2 in neutrophils, induces the opening of mitochondrial permeability transition pore (mPTP), promotes the increase of reactive oxygen species and mitochondrial ROS, and then leads to the rise of NET production, which is mainly manifested by the release of DNA reticular structure and the increased expression of NETs-related markers. The PI3K/AKT signaling pathway was activated in neutrophils, and the phosphorylation level was enhanced by FPR2 agonists in vitro. In vivo, increased expression of NETs markers was detected in the retina of diabetic mice and in FVM, vitreous fluid, and serum of PDR patients. Transgenic FPR2 deletion led to decreased NETs in the retina of diabetic mice. Furthermore, in vitro, inhibition of the LL37/FPR2/mPTP axis and PI3K/AKT signaling pathway decreased NET production induced by high glucose. These results suggested that FPR2 plays an essential role in regulating the production of NETs induced by HG, thus may be considered as one of the potential therapeutic targets.

Quantitative evaluation of citrullinated fibrinogen for detection of neutrophil extracellular traps

Activated neutrophils release neutrophil extracellular traps (NETs) composed of chromatin filaments containing bactericidal proteins and enzymes. This process, known as NETosis, is an innate host defense mechanism. However, NET accumulation can lead to uncontrolled inflammation and organ damage. Therefore, NET detection provides clinically important information for the assessment of inflammatory conditions. We investigated whether quantification of citrullinated fibrinogen (C-Fbg), which is catalyzed by peptidylarginine deiminase (PAD) released during NETosis, can be used to detect NETs. Human neutrophils were stimulated with fibrinogen using phorbol 12-myristate 13-acetate (PMA). The myeloperoxidase (MPO)-DNA complex and C-Fbg concentrations in the culture supernatants were quantified using an enzyme-linked immunosorbent assay. The protein levels of peptidylarginine deiminase 2 and 4 in culture supernatants and mRNA levels in PMA-stimulated neutrophils were also assessed. The levels of the MPO-DNA complex in the supernatants of PMA-stimulated neutrophils increased, indicating NETosis. C-Fbg level also increased, which was suppressed by both NETosis and PAD inhibitors. PAD2 was detected in the culture supernatant; however, PAD4, but not PAD2, mRNA levels increased in PMA-stimulated neutrophils. This study quantitatively demonstrates that fibrinogen is citrullinated by PAD derived from PMA-stimulated neutrophils upon NETosis. Although further studies are needed for clinical application, quantification of C-Fbg in blood may help detect the presence of NETs.

The Elevated Inflammatory Status of Neutrophils Is Related to In-Hospital Complications in Patients with Acute Coronary Syndrome and Has Important Prognosis Value for Diabetic Patients

Despite neutrophil involvement in inflammation and tissue repair, little is understood about their inflammatory status in acute coronary syndrome (ACS) patients with poor outcomes. Hence, we investigated the potential correlation between neutrophil inflammatory markers and the prognosis of ACS patients with/without diabetes and explored whether neutrophils demonstrate a unique inflammatory phenotype in patients experiencing an adverse in-hospital outcome. The study enrolled 229 ACS patients with or without diabetes. Poor evolution was defined as either death, left ventricular ejection fraction (LVEF) <40%, Killip Class 3/4, ventricular arrhythmias, or mechanical complications. Univariate and multivariate analyses were employed to identify clinical and paraclinical factors associated with in-hospital outcomes. Neutrophils isolated from fresh blood were investigated using qPCR, Western blot, enzymatic assay, and immunofluorescence. Poor evolution post-myocardial infarction (MI) was associated with increased number, activity, and inflammatory status of neutrophils, as indicated by significant increase of Erythrocyte Sedimentation Rate (ESR), C-reactive protein (CRP), fibrinogen, interleukin-1β (IL-1β), and, interleukin-6 (IL-6). Among the patients with complicated evolution, neutrophil activity had an important prognosis value for diabetics. Neutrophils from patients with unfavorable evolution revealed a pro-inflammatory phenotype with increased expression of CCL3, IL-1β, interleukin-18 (IL-18), S100A9, intracellular cell adhesion molecule-1 (ICAM-1), matrix metalloprotease (MMP-9), of molecules essential in reactive oxygen species (ROS) production p22phox and Nox2, and increased capacity to form neutrophil extracellular traps. Inflammation is associated with adverse short-term prognosis in acute ACS, and inflammatory biomarkers exhibit greater specificity in predicting short-term outcomes in diabetics. Moreover, neutrophils from patients with unfavorable evolution exhibit distinct inflammatory patterns, suggesting that alterations in the innate immune response in this subgroup may exert detrimental effects on disease progression.

NLRP3 inflammasome activation and NETosis positively regulate each other and exacerbate proinflammatory responses: implications of NETosis inhibition for acne skin inflammation treatment

Inflammasomes are multiprotein complexes involved in the host immune response to pathogen infections. Thus, inflammasomes participate in many conditions, such as acne. Recently, it was shown that NETosis, a type of neutrophil cell death, is induced by bacterial infection and is involved in inflammatory diseases such as delayed wound healing in patients with diabetes. However, the relationship between inflammasomes and NETosis in the pathogenesis of inflammatory diseases has not been well studied. In this study, we determined whether NETosis is induced in P. acnes-induced skin inflammation and whether activation of the nucleotide-binding domain, leucine-rich family, and pyrin domain-containing-3 (NLRP3) inflammasome is one of the key factors involved in NETosis induction in a mouse model of acne skin inflammation. We found that NETosis was induced in P. acnes-induced skin inflammation in mice and that inhibition of NETosis ameliorated P. acnes-induced skin inflammation. In addition, our results demonstrated that inhibiting inflammasome activation could suppress NETosis induction in mouse skin. These results indicate that inflammasomes and NETosis can interact with each other to induce P. acnes-induced skin inflammation and suggest that targeting NETosis could be a potential treatment for inflammasome-mediated diseases as well as NETosis-related diseases.

Blood Cell Ratios Unveiled: Predictive Markers of Myocardial Infarction Prognosis

BACKGROUND

Even if the management and treatment of patients with non-ST-elevation myocardial infarction (NSTEMI) have significantly evolved, it is still a burgeoning disease, an active volcano with very high rates of morbidity and mortality. Therefore, novel management and therapeutic strategies for this condition are urgently needed. Lately, theories related to the role of various blood cells in NSTEMI have emerged, with most of this research having so far been focused on correlating the ratios between various leukocyte types (neutrophil/lymphocyte ratio-NLR, neutrophil/monocyte ratio-NMR). But what about erythrocytes? Is there an interaction between these cells and leukocytes, and furthermore, can this relationship influence NSTEMI prognosis? Are they partners in crime?

METHODS

Through the present study, we sought, over a period of sixteen months, to evaluate the neutrophil/red blood cell ratio (NRR), monocyte/red blood cell ratio (MRR) and lymphocyte/red blood cell ratio (LRR), assessing their potential role as novel prognostic markers in patients with NSTEMI.

RESULTS

There was a statistically significant correlation between the NRR, LRR, MRR and the prognosis of NSTEMI patients.

CONCLUSIONS

These new predictive markers could represent the start of future innovative therapies that may influence crosstalk pathways and have greater benefits in terms of cardiac repair and the secondary prevention of NSTEMI.

Association of the neutrophil-to-lymphocyte ratio with the occurrence of venous thromboembolism and arterial thrombosis

OBJECTIVE

This study aimed to assess the association of the neutrophil-to-lymphocyte ratio (NLR) with the occurrence of venous thromboembolism (VTE) and arterial thrombosis (AT).

METHODS

This was a retrospective cross-sectional study including 585 medical records obtained from all consecutive patients who were suspected of having thrombosis.

RESULTS

The AT group had a higher neutrophil count and NLR and a lower lymphocyte count than the non-thrombosis group. Receiver operating characteristic curve analysis showed the ability of the NLR to predict the presence of AT. The cut-off value for the NLR was 4.44. No distinction was found in the NLR between the VTE and non-thrombosis groups. Regression analysis showed that a high NLR was an independent factor related to the presence of AT. Patients with an NLR ≥ 4.44 had a higher risk of AT than those with an NLR < 4.44 (odds ratio = 2.015, 95% confidence interval: 1.180-3.443).

CONCLUSION

A high NLR may be considered a predictive factor for the occurrence of AT, but an association with the presence of VTE was not found.

Neutrophil-Enriched Biomarkers and Long-Term Prognosis in Acute Coronary Syndrome: a Systematic Review and Meta-analysis

Activated neutrophils release a range of inflammatory products that represent potential biomarkers, and there is interest in the prognostic value of these in acute coronary syndrome (ACS) patients. We conducted a systematic review to examine neutrophil-enriched biomarkers and the occurrence of major adverse cardiovascular events (MACE) in patients with ACS. We identified twenty-seven studies including 17,831 patients with ACS. The most studied biomarkers were neutrophil gelatinase-associated lipocalin (NGAL) and myeloperoxidase (MPO). Meta-analyses showed that elevated NGAL was associated with higher MACE rates (unadjusted risk ratio (RR) 1.52, 95% CI 1.12-2.06, p = 0.006) as were elevated MPO levels (unadjusted RR 1.61, 95% CI 1.22-2.13, p = 0.01). There was limited data suggesting that increased levels of calprotectin, proteinase-3 and double-stranded DNA were also associated with MACE. These results suggest that higher levels of neutrophil-enriched biomarkers may be predictive of MACE in patients with ACS, although higher-quality studies are needed to confirm these observations.

An update on the cell-free DNA-derived methylome as a non-invasive biomarker for coronary artery disease

Cardiovascular diseases are the foremost contributor to global mortality, presenting a complex etiology and an expanding array of risk factors. Coronary artery disease characterized by atherosclerotic plaque build-up in the coronary arteries, imposes significant mortality and financial burdens, especially in low- and middle-income nations. The pathogenesis of coronary artery disease involves a multifaceted interplay of genetic, environmental, and epigenetic factors. Epigenetic regulation contributes to the dynamic control of gene expression without altering the underlying DNA sequence. The mounting evidence that highlights the pivotal role of epigenetic regulation in coronary artery disease development and progression, offering potential avenues for the development of novel diagnostic biomarkers and therapeutic targets. Abnormal DNA methylation patterns are linked to the modulation of gene expression involved in crucial processes like lipid metabolism, inflammation, and vascular function in the context of coronary artery disease. Cell-free DNA has become invaluable in tumor biology as a liquid biopsy, while its applications in coronary artery disease are limited, but intriguing. Atherosclerotic plaque rupture causes myocardial infarction, by depriving heart muscles of oxygen, releasing cell-free DNA from dead cardiac cells, and providing a minimally invasive source to explore tissue-specific epigenetic alterations. We discussed the methodologies for studying the global methylome and hydroxy-methylome landscape, their advantages, and limitations. It explores methylome alterations in coronary artery disease, considering risk factors and their relevance in coronary artery disease genesis. The review also details the implications of MI-derived cell-free DNA for developing minimally invasive biomarkers and associated challenges.

Colchicine Inhibits NETs and Alleviates Cardiac Remodeling after Acute Myocardial Infarction

PURPOSE

Colchicine, a multipotent anti-inflammatory drug, has been reported to alleviate cardiac remodeling and improve cardiac function after acute myocardial infarction (AMI). However, the underlying mechanism remains incompletely understood. Because neutrophils extracellular traps (NETs) enhance inflammation and participate in myocardial ischemia injury, and colchicine can inhibit NETosis, we thus aimed to determine whether colchicine exerts cardioprotective effects on AMI via suppressing NETs.

METHODS

Adult C57BL/6 mice were subjected to permanent ligation of the left anterior descending coronary artery and treated with colchicine (0.1 mg/kg/day) or Cl-amidine (10 mg/kg/day) for 7 or 28 days after AMI. Cardiac function was evaluated by echocardiography, and NETs detected by immunofluorescence. ROS production was detected using 2',7'-dichlorodihydrofluorescein diacetates (DCFH-DA) fluorometry. Intracellular Ca2+ concentration was assessed by a fluorometric ratio technique.

RESULTS

We found that colchicine treatment significantly increased mice survival (89.8% in the colchicine group versus 67.9% in control, n = 32 per group; log-rank test, p < 0.05) and improved cardiac function at day 7 (left ventricular ejection fraction (LVEF): 28.0 ± 9.2% versus 12.6 ± 3.9%, n = 8 per group; p < 0.001) and at day 28 (LVEF: 26.2 ± 7.2% versus 14.8 ± 6.7%, n = 8 per group; p < 0.001) post-AMI. In addition, the administration of colchicine inhibited NETs formation and inflammation. Furthermore, colchicine inhibited NETs formation by reducing NOX2/ROS production and Ca2+ influx. Moreover, prevention of NETs formation with Cl-amidine significantly alleviated AMI-induced cardiac remodeling.

CONCLUSIONS

Colchicine inhibited NETs and cardiac inflammation, and alleviated cardiac remodeling after acute myocardial infarction.

Low-Density Neutrophils Contribute to Subclinical Inflammation in Patients with Type 2 Diabetes

Type 2 diabetes (T2D) is characterized by low-grade inflammation. Low-density neutrophils (LDNs) represent normally less than 2% of total neutrophils but increase in multiple pathologies, releasing inflammatory cytokines and neutrophil extracellular traps (NETs). We assessed the count and role of high-density neutrophils (HDNs), LDNs, and NET-related activities in patients with T2D. HDNs and LDNs were purified by fluorescence-activated cell sorting (FACS) and counted by flow cytometry. Circulating inflammatory and NETs biomarkers were measured by ELISA (Enzyme Linked Immunosorbent Assay). NET formation was quantified by confocal microscopy. Neutrophil adhesion onto a human extracellular matrix (hECM) was assessed by optical microscopy. We recruited 22 healthy volunteers (HVs) and 18 patients with T2D. LDN counts in patients with diabetes were significantly higher (160%), along with circulating NETs biomarkers (citrullinated H3 histone (H3Cit), myeloperoxidase (MPO), and MPO-DNA (137%, 175%, and 69%, respectively) versus HV. Circulating interleukins (IL-6 and IL-8) and C-Reactive Protein (CRP) were significantly increased by 117%, 171%, and 79%, respectively, in patients compared to HVs. Isolated LDNs from patients expressed more H3Cit, MPO, and NETs, formed more NETs, and adhered more on hECM compared to LDNs from HVs. Patients with T2D present higher levels of circulating LDN- and NET-related biomarkers and associated pro-inflammatory activities.

Targeting RXFP1 by Ligustilide: A novel therapeutic approach for alcoholic hepatic steatosis

BACKGROUND

Ligustilide (Lig) is the main active ingredient of Umbelliferae Angelicae Sinensis Radix (Chinese Angelica) and Chuanxiong Rhizoma (Sichuan lovase rhizome). Lig possesses various pharmacological properties and could treat obesity by regulating energy metabolism. However, the impact and regulatory mechanism of Lig on alcoholic hepatic steatosis remains unclear.

PURPOSE

This study aimed to explore the therapeutic effect of Lig on alcoholic hepatic steatosis and its related pharmacological mechanism.

RESULTS

With chronic and binge ethanol feeding, liver tissue damage and lipid accumulation in mice suffering alcoholic hepatic steatosis were significantly improved after Lig treatment. Lig effectively regulated the expression levels of lipid metabolism-related proteins in alcoholic hepatic steatosis. In addition, Lig reduced RXFP1 expression, inhibited the activation of NLRP3 inflammasome, and blocked NET formation. Lig reduced the infiltration of immune cells to the liver and the further prevented the occurrence of alcohol-stimulated inflammatory response in liver. Lig significantly regulated lipid accumulation in alcohol exposed AML12 cells via modulating PPARα and SREBP1. In MPMs, Lig decreased the expression of RXFP1, inhibited the activation of NLRP3 in macrophages stimulated by LPS/ATP, and slowed down the occurrence of inflammatory response.

CONCLUSION

Lig sustained lipid metabolism homeostasis in alcoholic hepatic steatosis, through inhibiting the activation of NLRP3 inflammasomes and the formation of NETs, especially targeting RXFP1 in macrophages.

Unveiling the Web: Exploring the Multifaceted Role of Neutrophil Extracellular Traps in Ocular Health and Disease

Neutrophil extracellular traps (NETs) play an essential role in antimicrobial defense. However, NETs have also been shown to promote and mediate a wide spectrum of diseases, including cancer, diabetes mellitus, cardiovascular diseases, and ocular diseases. Data regarding NETs in ocular diseases remain limited. In physiological conditions, NETs protect the eye from debris and cleave proinflammatory cytokines, including several interleukins. On the other hand, NETs play a role in corneal diseases, such as dry eye disease and ocular graft-versus-host disease, where they promote acinar atrophy and delayed wound healing. Additionally, NET levels positively correlate with increased severity of uveitis. NETs have also been described in the context of diabetic retinopathy. Although increased NET biomarkers are associated with an increased risk of the disease, NETs also assist in the elimination of pathological blood vessels and the regeneration of normal vessels. Targeting NET pathways for the treatment of ocular diseases has shown promising outcomes; however, more studies are still needed in this regard. In this article, we summarize the literature on the protective roles of NETs in the eye. Then, we describe their pathogenetic effects in ocular diseases, including those of the cornea, uvea, and retinal blood vessels. Finally, we describe the therapeutic implications of targeting NETs in such conditions.

Moxibustion-mediated alleviation of synovitis in rats with rheumatoid arthritis through the regulation of NLRP3 inflammasome by modulating neutrophil extracellular traps

Purpose

This study investigates the potential mechanism of moxibustion in the treatment of rheumatoid arthritis (RA) by regulating the neutrophil extracellular trap (NET)/NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome axis with the use of a rat model with adjuvant arthritis (AA).

Methods

Four groups, including normal control (NC), AA, moxibustion (MOX), and chlor-amidine (Cl-amidine) were created from 24 Wistar male rats (6 rats/group). After the intervention and treatment respectively, the joint swelling degree (JSD) and arthritis index (AI) were compared. The pathological changes of synovium were observed with hematoxylin and eosin staining and transmission electron microscopy. The formation of NETs in synovial tissues was detected with immunofluorescence staining. The protein expression of myeloperoxidase (MPO), neutrophil elastase (NE), citrullinated histone (Cit-H3), acyl arginine deiminase 4 (PAD-4), and NLRP3 was measured in the synovium of rat ankle joints with western blotting, and the levels of anti-cyclic citrullinated peptide antibody (CCP-Ab) and interleukin (IL)-1β were examined in rat serum with ELISA.

Results

AA modeling markedly increased JSD, AI, synovial protein expression of MPO, NE, Cit-H3, PAD-4, and NLRP3, and serum levels of CCP-Ab and IL-1β in rats (P < 0.01). JSD and AI, as well as the levels of MPO, NE, Cit-H3, PAD-4, NLRP3, CCP-Ab, and IL-1β, were significantly lowered in AA rats by MOX and Cl-amidine (P < 0.01). In addition, AA modeling caused severe pathological injury in the synovium of rats, which was annulled by MOX and Cl-amidine. The formation of NETs in synovium was substantially promoted in rats by AA modeling and was significantly reduced in AA rats after the treatment.

Conclusion

Moxibustion can markedly alleviate synovitis and repress inflammatory factor release in AA rats, which may be achieved by diminished synthesis of NETs or their constituents and the blocked formation of NLRP3 inflammasome.

The tumor-derived cytokine Chi3l1 induces neutrophil extracellular traps that promote T cell exclusion in triple-negative breast cancer

In triple-negative breast cancer (TNBC), stromal restriction of CD8+ T cells associates with poor clinical outcomes and lack of responsiveness to immune-checkpoint blockade (ICB). To identify mediators of T cell stromal restriction, we profiled murine breast tumors lacking the transcription factor Stat3, which is commonly hyperactive in breast cancers and promotes an immunosuppressive tumor microenvironment. Expression of the cytokine Chi3l1 was decreased in Stat3-/- tumors. CHI3L1 expression was elevated in human TNBCs and other solid tumors exhibiting T cell stromal restriction. Chi3l1 ablation in the polyoma virus middle T (PyMT) breast cancer model generated an anti-tumor immune response and delayed mammary tumor onset. These effects were associated with increased T cell tumor infiltration and improved response to ICB. Mechanistically, Chi3l1 promoted neutrophil recruitment and neutrophil extracellular trap formation, which blocked T cell infiltration. Our findings provide insight into the mechanism underlying stromal restriction of CD8+ T cells and suggest that targeting Chi3l1 may promote anti-tumor immunity in various tumor types.

Systemic immune-inflammation index (SII) and the risk of all-cause, cardiovascular, and cardio-cerebrovascular mortality in the general population

BACKGROUND

An elevated systemic immune-inflammation index (SII) is associated with higher mortality in patients with coronary artery disease and other diseases. However, the potential of SII for predicting mortality in the general population has been underexplored. Therefore, this study aimed to analyze the relationship between the SII and all-cause, cardiovascular disease, and cardiocerebrovascular disease mortality in the general population.

METHODS

This study involved 26,855 participants (≥ 18 years) from the National Health and Nutrition Examination Survey 1999-2014 who were grouped according to the SII tertiles. Survival differences between the groups were analyzed using log-rank tests and Kaplan-Meier plots. Furthermore, multivariate Cox regression and restricted cubic spline analyses were used to examine the relationship between the SII and all-cause, cardiovascular, and cardio-cerebrovascular mortality.

RESULTS

Overall, 1947 (7.425%) participants died following an average follow-up of 87.99 ± 54.04 months. Among these, 325 (1.210%) deaths were related to cardiovascular diseases and 392 (1.459%) to cardio-cerebrovascular mortality. Kaplan-Meier analysis revealed statistically significant differences in all-cause, cardiovascular, and cerebrovascular mortality between the SII tertiles (log-rank test: all P < 0.001). Multi-adjusted models showed that participants in the highest tertile of SII had a higher risk of death from all-cause (hazard ratio [HR] = 1.48, 95% confidence interval [CI] 1.48-1.48) and cardiovascular mortality (HR = 1.60, 95% CI 1.60-1.61) compared with those in the lowest tertile. In addition, the restricted cubic spline curve indicated a nonlinear association between SII and all-cause mortality (P < 0.001), with threshold value of SII at 18.284. There was a 15% decrease in the risk of all-cause mortality for each twofold change in SII on the left flank (HR = 0.85, 95% CI 0.69-1.05) and a 42% increase (HR = 1.42, 95% CI 1.23-1.64) on the right flank of the inflection point. In addition, the risk of cardiovascular mortality increased nonlinearly by 39% per twofold change in SII (HR = 1.39, 95% CI 1.07-1.81). There was also a nonlinear increase in the risk of cardio-cerebrovascular mortality per twofold change in SII (HR = 1.29, 95% CI 1.00-1.66).

CONCLUSIONS

In the general population, the SII was significantly associated with all-cause, cardiovascular, and cardio-cerebrovascular mortality, regardless of the established risk factors.

DEL-1 deficiency aggravates pressure overload-induced heart failure by promoting neutrophil infiltration and neutrophil extracellular traps formation

Recent studies have shown that neutrophils play an important role in the development and progression of heart failure. Developmental endothelial locus-1 (DEL-1) is an anti-inflammatory glycoprotein that has been found to have protective effects in various cardiovascular diseases. However, the role of DEL-1 in chronic heart failure is not well understood. In a mouse model of pressure overload-induced non-ischemic cardiac failure, we found that neutrophil infiltration in the heart increased and DEL-1 levels decreased in the early stages of heart failure. DEL-1 deficiency worsened pressure overload-induced cardiac dysfunction and remodeling in mice. Mechanistically, DEL-1 deficiency promotes neutrophil infiltration and the formation of neutrophil extracellular traps (NETs) through the regulation of P38 signaling. In vitro experiments showed that DEL-1 can inhibit P38 signaling and NETs formation in mouse neutrophils in a MAC-1-dependent manner. Depleting neutrophils, inhibiting NETs formation, and inhibiting P38 signaling all reduced the exacerbation of heart failure caused by DEL-1 deletion. Overall, our findings suggest that DEL-1 deficiency worsens pressure overload-induced heart failure by promoting neutrophil infiltration and NETs formation.

What is the role of the neutrophil extracellular traps in the cardiovascular disease burden associated with hemodialysis bioincompatibility?

Despite significant progress in dialysis modalities, intermittent renal replacement therapy remains an "unphysiological" treatment that imperfectly corrects uremic disorders and may lead to low-grade chronic inflammation, neutrophil activation, and oxidative stress due to repetitive blood/membrane interactions contributing to the "remaining uremic syndrome" and cardiovascular disease burden of hemodialysis patients. Understanding dialysis bioincompatibility pathways still remains a clinical and biochemical challenge. Indeed, surrogate biomarkers of inflammation including C-reactive protein could not discriminate between all components involved in these complex pathways. A few examples may serve to illustrate the case. Cytokine release during dialysis sessions may be underestimated due to their removal using high-flux dialysis or hemodiafiltration modalities. Complement activation is recognized as a key event of bioincompatibility. However, it appears as an early and transient event with anaphylatoxin level normalization at the end of the dialysis session. Complement activation is generally assumed to trigger leukocyte stimulation leading to proinflammatory mediators' secretion and oxidative burst. In addition to being part of the innate immune response involved in eliminating physically and enzymatically microbes, the formation of Neutrophil Extracellular Traps (NETs), known as NETosis, has been recently identified as a major harmful component in a wide range of pathologies associated with inflammatory processes. NETs result from the neutrophil degranulation induced by reactive oxygen species overproduction via NADPH oxidase and consist of modified chromatin decorated with serine proteases, elastase, bactericidal proteins, and myeloperoxidase (MPO) that produces hypochlorite anion. Currently, NETosis remains poorly investigated as a sensitive and integrated marker of bioincompatibility in dialysis. Only scarce data could be found in the literature. Oxidative burst and NADPH oxidase activation are well-known events in the bioincompatibility phenomenon. NET byproducts such as elastase, MPO, and circulating DNA have been reported to be increased in dialysis patients more specifically during dialysis sessions, and were identified as predictors of poor outcomes. As NETs and MPO could be taken up by endothelium, NETs could be considered as a vascular memory of intermittent bioincompatibility phenomenon. In this working hypothesis article, we summarized the puzzle pieces showing the involvement of NET formation during hemodialysis and postulated that NETosis may act as a disease modifier and may contribute to the comorbid burden associated with dialysis bioincompatibility.

PREDICTIVE VALUE OF NEUTROPHIL EXTRACELLULAR TRAP COMPONENTS FOR 28-DAY ALL-CAUSE MORTALITY IN PATIENTS WITH CARDIAC ARREST: A PILOT OBSERVATIONAL STUDY

ABSTRACT

Background: Ischemia-reperfusion after cardiac arrest (CA) activates peptidyl arginine deiminase and citrullinated histone H3 (CitH3), which leads to the formation of neutrophil extracellular traps (NETs). This study attempted to determine the alterations in NET components in post-CA patients as well as analyze the association of NETs with 28-day all-cause mortality. Methods : In this study, 95 patients with restoration of spontaneous circulation (ROSC) after CA were included. They were categorized into the survivor group (n = 32) and the nonsurvivor group (n = 63) according to their 28-day survival statuses. The control group comprised 20 healthy individuals. The blood samples were collected from the patients on days 1, 3, and 7 after ROSC and from the control subjects at the time of enrollment. The serum cell-free DNA (cfDNA) level was determined using the fluorescent labeling method, and the serum concentrations of NET components, including CitH3, myeloperoxidase, neutrophil elastase, and nucleosomes, were estimated using the enzyme-linked immunosorbent assay. Results : Compared with the control group, the serum NET components were significantly increased in the patients 1 week after ROSC (all P < 0.05). These components were significantly higher in the nonsurvivor group than in the survivor group (all P < 0.05). Spearman correlational analysis revealed that the components were positively correlated with Acute Physiology and Chronic Health Evaluation II scores (both P < 0.05). Binary logistic regression analysis indicated that serum cfDNA, CitH3, and nucleosomes on days 1 and 3 after ROSC were independent predictors of 28-day all-cause mortality. Furthermore, these parameters on day 1 after ROSC had the biggest areas under the receiver operating characteristic curves (0.876, 0.862, and 0.861, respectively). Conclusions: Elevated serum levels of cfDNA, CitH3, myeloperoxidase, neutrophil elastase, and nucleosomes were positively correlated with disease severity after ROSC. However, only serum CitH3, cfDNA, and nucleosomes on day 1 after ROSC showed a good predictive value for 28-day all-cause mortality.

Interactions between neutrophils and T-helper 17 cells

Neutrophils comprise the majority of immune cells in human peripheral circulation, have potent antimicrobial activities, and are clinically significant in their abundance, heterogeneity, and subcellular localization. In the past few years, the role of neutrophils as components of the innate immune response has been studied in numerous ways, and these cells are crucial in fighting infections, autoimmune diseases, and cancer. T-helper 17 (Th17) cells that produce interleukin 17 (IL-17) are critical in fighting infections and maintaining mucosal immune homeostasis, whereas they mediate several autoimmune diseases. Neutrophils affect adaptive immune responses by interacting with adaptive immune cells. In this review, we describe the physiological roles of both Th17 cells and neutrophils and their interactions and briefly describe the pathological processes in which these two cell types participate. We provide a summary of relevant drugs targeting IL-17A and their clinical trials. Here, we highlight the interactions between Th17 cells and neutrophils in diverse pathophysiological situations.

Bioinformatics analysis of copper death gene in diabetic immune infiltration

BACKGROUND

Copper plays an important role in the human body and is potentially related to the development of diabetes. The mechanism of copper death gene regulating immune infiltration in diabetes has not been studied.

METHODS

Download microarray data from healthy normal and diabetic patients from the GEO database. The identification of differentially expressed genes (DEGs) was analyzed by gene enrichment. Using String online database and Cytoscape software to interact with the protein interaction network and make visual analysis. Using Wilcox analyze the correlation between the copoer death gene and diabetic mellitus. Analysis of the correlation between immune penetration cells and functions, and the difference between the diabetes group and the control group, screening the copper death gene associated with diabetes, and predicting the upper top of microRNA (miRNA) through the Funrich software.

RESULTS

According to the identification of differential genes in 25 samples of GSE25724 and GSE95849 data sets, 328 differential genes were identified by consensus, including 190 up-regulated genes and 138 down-regulated genes (log2FC = 2, P < .01). KEGG results showed that neurodegeneration-multiple disease pathways were most significantly upregulated, followed by Huntington disease. According to Cytohubba, the TOP10 genes HCK, FPR1, MNDA, AQP9, TLR8, CXCR1, CSF3R, VNN2, TLR4, and CCR5 are down-regulated genes, which are mostly enriched in neutrophils. Immunoinfiltration-related heat maps show that Macrophage was strongly positively correlated with Activated dendritic cell, Mast cell, Neutrophil, and Regulatory T cell showed a strong positive correlation. Neutrophil was strongly positively correlated with Activated dendritic cell, Mast cell, and Regulatory T cell. Differential analysis of immune infiltration showed that Neutroph, Mast cell, Activated B cell, Macrophage and Eosinophil were significantly increased in the diabetic group. Central memory CD4 T cell (P < .001), Plasmacytoid dendritic cell, Immature dendritic cell, and Central memory CD8 T cell, etal were significantly decreased. DBT, SLC31A1, ATP7A, LIAS, ATP7B, PDHA1, DLST, PDHB, GCSH, LIPT1, DLD, FDX1, and DLAT genes were significantly associated with one or more cells and their functions in immune invasion. Forty-one miRNA.

CONCLUSIONS

Copper death is closely related to the occurrence of diabetes. Copper death genes may play an important role in the immune infiltration of diabetes.

Neutrophil extracellular traps and long COVID

Post-acute COVID-19 sequelae, commonly known as long COVID, encompasses a range of systemic symptoms experienced by a significant number of COVID-19 survivors. The underlying pathophysiology of long COVID has become a topic of intense research discussion. While chronic inflammation in long COVID has received considerable attention, the role of neutrophils, which are the most abundant of all immune cells and primary responders to inflammation, has been unfortunately overlooked, perhaps due to their short lifespan. In this review, we discuss the emerging role of neutrophil extracellular traps (NETs) in the persistent inflammatory response observed in long COVID patients. We present early evidence linking the persistence of NETs to pulmonary fibrosis, cardiovascular abnormalities, and neurological dysfunction in long COVID. Several uncertainties require investigation in future studies. These include the mechanisms by which SARS-CoV-2 brings about sustained neutrophil activation phenotypes after infection resolution; whether the heterogeneity of neutrophils seen in acute SARS-CoV-2 infection persists into the chronic phase; whether the presence of autoantibodies in long COVID can induce NETs and protect them from degradation; whether NETs exert differential, organ-specific effects; specifically which NET components contribute to organ-specific pathologies, such as pulmonary fibrosis; and whether senescent cells can drive NET formation through their pro-inflammatory secretome in long COVID. Answering these questions may pave the way for the development of clinically applicable strategies targeting NETs, providing relief for this emerging health crisis.

Skin wound healing as a mirror to cardiac wound healing

NEW FINDINGS

What is the topic of this review? Wound healing is a general response of the body to injury and can be divided into three phases: inflammation, inflammation resolution and repair. In this review, we compare the wound-healing response of the skin after an injury and the wound-healing response of the heart after a myocardial infarction. What advances does it highlight? We highlight differences and similarities between skin and cardiac wound healing and summarize how skin can be used to provide information about the heart.

ABSTRACT

Wound healing is a general response of the body to injury. All organs share in common three response elements to wound healing: inflammation to prevent infection and stimulate the removal of dead cells, active anti-inflammatory signalling to turn off the inflammatory response, and a repair phase characterized by extracellular matrix scar formation. The extent of scar formed depends on the ability of endogenous cells that populate each organ to regenerate. The skin has keratinocytes that have regenerative capacity, and in general, wounds are fully re-epithelialized. Heart, in contrast, has cardiac myocytes that have little to no regenerative capacity, and necrotic myocytes are entirely replaced by scars. Despite differences in tissue regeneration, the skin and heart share many wound-healing properties that can be exploited to predict the cardiac response to pathology. We summarize in this review article our current understanding of how the response of the skin to a wounding event can inform us about the ability of the myocardium to respond to a myocardial infarction.

Research progress on the neutrophil components and their interactions with immune cells in the development of psoriasis

BACKGROUND

Psoriasis is an immune-mediated chronic inflammatory disease, and currently it is widely believed that the IL-23/IL-17 axis and Th17 cells play a critical and central role. However, increasing evidence suggests that neutrophils may interact with a variety of immune cells to play an indispensable role in psoriasis.

MATERIALS AND METHODS

We searched the recent literature on psoriasis and neutrophils through databases such as PubMed and CNKI, and summarized the findings to draw conclusions.

RESULTS

Neutrophils can promote the development of psoriasis by secreting IL-23, IL-17, and cytokines with TH17 cell chemotaxis. Activated keratinocytes (KCs) can attract and activate neutrophils, induce the formation of neutrophil extracellular traps (NETs). KCs can also expose self-antigens which lead to strong autoimmune reactions. The granule proteins secreted by activated neutrophils can activate IL-36, which converts vulgaris psoriasis to generalized pustular psoriasis (GPP).

CONCLUSION

The function of neutrophils components and the interaction between neutrophils and immune cells play an essential role in the pathogenesis of psoriasis. The aim is to provide a theoretical basis for the exploration of targeted clinical treatments and fundamental research on the pathogenesis of psoriasis.

Cardiovascular disease biomarkers derived from circulating cell-free DNA methylation

Acute coronary syndrome (ACS) remains a major cause of worldwide mortality. The syndrome occurs when blood flow to the heart muscle is decreased or blocked, causing muscle tissues to die or malfunction. There are three main types of ACS: Non-ST-elevation myocardial infarction, ST-elevation myocardial infarction, and unstable angina. The treatment depends on the type of ACS, and this is decided by a combination of clinical findings, such as electrocardiogram and plasma biomarkers. Circulating cell-free DNA (ccfDNA) is proposed as an additional marker for ACS since the damaged tissues can release DNA to the bloodstream. We used ccfDNA methylation profiles for differentiating between the ACS types and provided computational tools to repeat similar analysis for other diseases. We leveraged cell type specificity of DNA methylation to deconvolute the ccfDNA cell types of origin and to find methylation-based biomarkers that stratify patients. We identified hundreds of methylation markers associated with ACS types and validated them in an independent cohort. Many such markers were associated with genes involved in cardiovascular conditions and inflammation. ccfDNA methylation showed promise as a non-invasive diagnostic for acute coronary events. These methods are not limited to acute events, and may be used for chronic cardiovascular diseases as well.

NLRP3 Exacerbate NETosis-Associated Neuroinflammation in an LPS-Induced Inflamed Brain

Neutrophil extracellular traps (NETs) exert a novel function of trapping pathogens. Released NETs can accumulate in inflamed tissues, be recognized by other immune cells for clearance, and lead to tissue toxicity. Therefore, the deleterious effect of NET is an etiological factor, causing several diseases directly or indirectly. NLR family pyrin domain containing 3 (NLRP3) in neutrophils is pivotal in signaling the innate immune response and is associated with several NET-related diseases. Despite these observations, the role of NLRP3 in NET formation in neuroinflammation remains elusive. Therefore, we aimed to explore NET formation promoted by NLRP3 in an LPS-induced inflamed brain. Wild-type and NLRP3 knockout mice were used to investigate the role of NLRP3 in NET formation. Brain inflammation was systemically induced by administering LPS. In such an environment, the NET formation was evaluated based on the expression of its characteristic indicators. DNA leakage and NET formation were analyzed in both mice through Western blot, flow cytometry, and in vitro live cell imaging as well as two-photon imaging. Our data revealed that NLRP3 promotes DNA leakage and facilitates NET formation accompanied by neutrophil death. Moreover, NLRP3 is not involved in neutrophil infiltration but is predisposed to boost NET formation, which is accompanied by neutrophil death in the LPS-induced inflamed brain. Furthermore, either NLRP3 deficiency or neutrophil depletion diminished pro-inflammatory cytokine, IL-1β, and alleviated blood-brain barrier damage. Overall, the results suggest that NLRP3 exacerbates NETosis in vitro and in the inflamed brain, aggravating neuroinflammation. These findings provide a clue that NLRP3 would be a potential therapeutic target to alleviate neuroinflammation.

Identification and Validation of Molecular Subtype and Prognostic Signature for Bladder Cancer Based on Neutrophil Extracellular Traps

Neutrophil extracellular traps (NETs) could promote tumor growth and distant metastases. Molecular subtypes of bladder cancer were identified with consensus cluster analysis. A NETs-related prognostic signature was constructed with LASSO cox regression analysis. As a result, we identified three subtypes of bladder cancer, which had a distinct difference in prognosis, immune microenvironment, TIDE score, mRNAsi score and IC50 score. We also developed a prognostic signature based on 5 NETs-related genes, which had a good performance in clinical outcome prediction of bladder cancer. These results may provide more data about the vital role of NETs in bladder cancer.

Inhibition of Myeloperoxidase Pro-Fibrotic Effect by Noscapine in Equine Endometrium

Myeloperoxidase is an enzyme released by neutrophils when neutrophil extracellular traps (NETs) are formed. Besides myeloperoxidase activity against pathogens, it was also linked to many diseases, including inflammatory and fibrotic ones. Endometrosis is a fibrotic disease of the mare endometrium, with a large impact on their fertility, where myeloperoxidase was shown to induce fibrosis. Noscapine is an alkaloid with a low toxicity, that has been studied as an anti-cancer drug, and more recently as an anti-fibrotic molecule. This work aims to evaluate noscapine inhibition of collagen type 1 (COL1) induced by myeloperoxidase in equine endometrial explants from follicular and mid-luteal phases, at 24 and 48 h of treatment. The transcription of collagen type 1 alpha 2 chain (COL1A2), and COL1 protein relative abundance were evaluated by qPCR and Western blot, respectively. The treatment with myeloperoxidase increased COL1A2 mRNA transcription and COL1 protein, whereas noscapine was able to reduce this effect with respect to COL1A2 mRNA transcription, in a time/estrous cycle phase-dependent manner (in explants from the follicular phase, at 24 h of treatment). Our study indicates that noscapine is a promising drug to be considered as an anti-fibrotic molecule to prevent endometrosis development, making noscapine a strong candidate to be applied in future endometrosis therapies.

The mechanism and therapy of aortic aneurysms

Aortic aneurysm is a chronic aortic disease affected by many factors. Although it is generally asymptomatic, it poses a significant threat to human life due to a high risk of rupture. Because of its strong concealment, it is difficult to diagnose the disease in the early stage. At present, there are no effective drugs for the treatment of aneurysms. Surgical intervention and endovascular treatment are the only therapies. Although current studies have discovered that inflammatory responses as well as the production and activation of various proteases promote aortic aneurysm, the specific mechanisms remain unclear. Researchers are further exploring the pathogenesis of aneurysms to find new targets for diagnosis and treatment. To better understand aortic aneurysm, this review elaborates on the discovery history of aortic aneurysm, main classification and clinical manifestations, related molecular mechanisms, clinical cohort studies and animal models, with the ultimate goal of providing insights into the treatment of this devastating disease. The underlying problem with aneurysm disease is weakening of the aortic wall, leading to progressive dilation. If not treated in time, the aortic aneurysm eventually ruptures. An aortic aneurysm is a local enlargement of an artery caused by a weakening of the aortic wall. The disease is usually asymptomatic but leads to high mortality due to the risk of artery rupture.

Carnosic acid suppressed the formation of NETs in alcoholic hepatosteatosis based on P2X7R-NLRP3 axis

BACKGROUND

Alcoholic liver disease (ALD) is accompanied by a disruption of lipid metabolism and an inflammatory response in the liver during the process of disease. Carnosic acid (CA), a natural diterpene extracted from Rosmarinus officinalis (rosemary) and Salvia officinalis (sage), has more pharmacological activities, which is known to be useful in the treatment of obesity and acts by regulating energy metabolism. However, the role and regulation mechanism of CA against ALD remain unclear.

HYPOTHESIS

We hypothesized that CA might improve alcoholic-induced hepatosteatosis.

STUDY DESIGN AND METHODS

The alcoholic liver disease model was established a mouse chronic ethanol feeding by Lieber-DeCarli control liquid feed (10 d) plus a single binge with or without CA administration. AML12 cells were exposed to ethanol for 24 h. Murine peritoneal macrophages (MPM) were stimulated with LPS and ATP.

RESULTS

CA ameliorated lipid accumulation in the liver of mice in the NIAAA model, acting by inhibiting the expression of genes related to lipid synthesis. CA reduced alcohol-induced immune cell infiltration in the liver, and inhibited the activation of P2X7R-NLRP3 inflammasome, meanwhile blocked the formation of NETs in mouse livers tissue. In AML12 cells, CA attenuated the lipid accumulation triggered by ethanol stimulation, which was achieved by inhibiting the expression of SREBP1 and CA reduced the release of inflammatory factor IL-1β by inhibiting the activation of P2X7R-NLRP3. In MPM, IL-1β and HMGB1 were reduced after LPS/ATP stimulation in CA-treated cells and supernatant.

CONCLUSIONS

CA attenuated alcohol-induced fat accumulation, suppressed the formation of NETs based on P2X7R-NLRP3 axis in mouse livers. Our data indicated that CA exerted hepatoprotective effects, which might be a promising candidate.

Neutrophil Extracellular Traps and NLRP3 Inflammasome: A Disturbing Duo in Atherosclerosis, Inflammation and Atherothrombosis

Atherosclerosis is the formation of plaque within arteries due to overt assemblage of fats, cholesterol and fibrous material causing a blockage of the free flow of blood leading to ischemia. It is harshly impinging on health statistics worldwide because of being principal cause of high morbidity and mortality for several diseases including rheumatological, heart and brain disorders. Atherosclerosis is perpetuated by pro-inflammatory and exacerbated by pro-coagulatory mediators. Besides several other pathways, the formation of neutrophil extracellular traps (NETs) and the activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome contribute significantly to the initiation and propagation of atherosclerotic plaque for its worst outcomes. The present review highlights the contribution of these two disturbing processes in atherosclerosis, inflammation and atherothrombosis in their individual as well as collaborative manner.

The Role of Neutrophils in Lower Limb Peripheral Artery Disease: State of the Art and Future Perspectives

In recent years, increasing attention has been paid to the role of neutrophils in cardiovascular (CV) disease (CVD) with evidence supporting their role in the initiation, progression, and rupture of atherosclerotic plaque. Although these cells have long been considered as terminally differentiated cells with a relatively limited spectrum of action, recent research has revealed intriguing novel cellular functions, including neutrophil extracellular trap (NET) generation and inflammasome activation, which have been linked to several human diseases, including CVD. While most research to date has focused on the role of neutrophils in coronary artery and cerebrovascular diseases, much less information is available on lower limb peripheral artery disease (PAD). PAD is a widespread condition associated with great morbidity and mortality, though physician and patient awareness of the disease remains low. To date, several studies have produced some evidence on the role of certain biomarkers of neutrophil activation in this clinical setting. However, the etiopathogenetic role of neutrophils, and in particular of some of the newly discovered mechanisms, has yet to be fully elucidated. In the future, complementary assessment of neutrophil activity should improve CV risk stratification and provide personalized treatments to patients with PAD. This review aims to summarize the basic principles and recent advances in the understanding of neutrophil biology, current knowledge about the role of neutrophils in atherosclerosis, as well as available evidence on their role of PAD.

Neutrophil Extracellular Traps in Cerebral Ischemia/Reperfusion Injury: Friend and Foe

Cerebral ischemic injury, one of the leading causes of morbidity and mortality worldwide, triggers various central nervous system (CNS) diseases, including acute ischemic stroke (AIS) and chronic ischemia-induced Alzheimer's disease (AD). Currently, targeted therapies are urgently needed to address neurological disorders caused by cerebral ischemia/reperfusion injury (CI/RI), and the emergence of neutrophil extracellular traps (NETs) may be able to relieve the pressure. Neutrophils are precursors to brain injury following ischemic stroke and exert complicated functions. NETs extracellularly release reticular complexes of neutrophils, i.e., double-stranded DNA (dsDNA), histones, and granulins. Paradoxically, NETs play a dual role, friend and foe, under different conditions, for example, physiological circumstances, infection, neurodegeneration, and ischemia/reperfusion. Increasing evidence indicates that NETs exert anti-inflammatory effects by degrading cytokines and chemokines through protease at a relatively stable and moderate level under physiological conditions, while excessive amounts of NETs release (NETosis) irritated by CI/RI exacerbate the inflammatory response and aggravate thrombosis, disrupt the blood-brain barrier (BBB), and initiates sequential neuron injury and tissue damage. This review provides a comprehensive overview of the machinery of NETs formation and the role of an abnormal cascade of NETs in CI/RI, as well as other ischemia-induced neurological diseases. Herein, we highlight the potential of NETs as a therapeutic target against ischemic stroke that may inspire translational research and innovative clinical approaches.

Identification and validation of the molecular subtype and prognostic signature for clear cell renal cell carcinoma based on neutrophil extracellular traps

Background: Renal cell carcinoma (RCC) is one of the most common cancers, with an annual incidence of nearly 400,000 cases worldwide. Increasing evidence has also demonstrated the vital role of neutrophil extracellular traps (NETs) in cancer progression and metastatic dissemination. Methods: Consensus cluster analysis was performed to determine the number of ccRCC subtypes. The Kruskal-Wallis test or Student t-test was performed to evaluate the difference of infiltrating immune cell and gene expression in different groups. The Kaplan-Meier (KM) method was used to draw the survival curve. LASSO cox regression analysis was conducted to construct a NET-related prognostic signature. We also constructed a lncRNA-miRNA-mRNA regulatory axis by several miRNA and lncRNA target databases. Results: A total of 23 differentially expressed NET-related genes were obtained in ccRCC. Three clusters of ccRCC cases with significant difference in prognosis, immune infiltration, and chemotherapy and targeted therapy were identified. LASSO Cox regression analysis identified a NET-related prognostic signature including six genes (G0S2, DYSF, MMP9, SLC22A4, SELP, and KCNJ15), and this signature had a good performance in predicting the overall survival of ccRCC patients. The expression of prognostic signature genes was significantly correlated with the pTMN stage, immune infiltration, tumor mutational burdens, microsatellite instability, and drug sensitivity of ccRCC patients. MMP9 was identified as the hub gene. We also identified the lncRNA UBA6-AS1/miR-149-5p/MMP9 regulatory axis for the progression of ccRCC. Conclusion: Collectively, the current study identified three molecular clusters and a prognostic signature for ccRCC based on neutrophil extracellular traps. Integrative transcriptome analyses plus clinical sample validation may facilitate the biomarker discovery and clinical transformation.

Interleukin-33 Induces Neutrophil Extracellular Trap (NET) Formation and Macrophage Necroptosis via Enhancing Oxidative Stress and Secretion of Proatherogenic Factors in Advanced Atherosclerosis

Interleukin-33 (IL-33) acts as an 'alarmin', and its role has been demonstrated in driving immune regulation and inflammation in many human diseases. However, the precise mechanism of action of IL-33 in regulating neutrophil and macrophage functioning is not defined in advanced atherosclerosis (aAT) patients. Further, the role of IL-33 in neutrophil extracellular trap (NET) formation in aAT and its consequent effect on macrophage function is not known. In the present study, we recruited n = 52 aAT patients and n = 52 control subjects. The neutrophils were isolated from both groups via ficoll/percoll-based density gradient centrifugation. The effect of IL-33 on the NET formation ability of the neutrophils was determined in both groups. Monocytes, isolated via a positive selection method, were used to differentiate them into macrophages from each of the study subjects and were challenged by IL-33-primed NETs, followed by the measurement of oxidative stress by calorimetric assay and the expression of the proinflammatory molecules by quantitative PCR (qPCR). Transcript and protein expression was determined by qPCR and immunofluorescence/ELISA, respectively. The increased expression of IL-33R (ST-2) was observed in the neutrophils, along with an increased serum concentration of IL-33 in aAT compared to the controls. IL-33 exacerbates NET formation via specifically upregulating CD16 expression in aAT. IL-33-primed NETs/neutrophils increased the cellular oxidative stress levels in the macrophages, leading to enhanced macrophage necroptosis and the release of atherogenic factors and matrix metalloproteinases (MMPs) in aAT compared to the controls. These findings suggested a pathogenic effect of the IL-33/ST-2 pathway in aAT patients by exacerbating NET formation and macrophage necroptosis, thereby facilitating the release of inflammatory factors and the release of MMPs that may be critical for the destabilization/rupture of atherosclerotic plaques in aAT. Targeting the IL-33/ST-2-NETs axis may be a promising therapeutic target for preventing plaque instability/rupture and its adverse complications in aAT.

Neutrophil Extracellular Traps in Asthma: Friends or Foes?

Asthma is a chronic inflammatory disease characterized by variable airflow limitation and airway hyperresponsiveness. A plethora of immune and structural cells are involved in asthma pathogenesis. The roles of neutrophils and their mediators in different asthma phenotypes are largely unknown. Neutrophil extracellular traps (NETs) are net-like structures composed of DNA scaffolds, histones and granular proteins released by activated neutrophils. NETs were originally described as a process to entrap and kill a variety of microorganisms. NET formation can be achieved through a cell-death process, termed NETosis, or in association with the release of DNA from viable neutrophils. NETs can also promote the resolution of inflammation by degrading cytokines and chemokines. NETs have been implicated in the pathogenesis of various non-infectious conditions, including autoimmunity, cancer and even allergic disorders. Putative surrogate NET biomarkers (e.g., double-strand DNA (dsDNA), myeloperoxidase-DNA (MPO-DNA), and citrullinated histone H3 (CitH3)) have been found in different sites/fluids of patients with asthma. Targeting NETs has been proposed as a therapeutic strategy in several diseases. However, different NETs and NET components may have alternate, even opposite, consequences on inflammation. Here we review recent findings emphasizing the pathogenic and therapeutic potential of NETs in asthma.