Inflammation. Neutrophil extracellular traps license macrophages for cytokine production in atherosclerosis

Neutrophils modulate natural killer-mediated osteoclastogenesis during Aggregatibacteractinomycetemcomitans (JP2 clone) infection

The study investigates the interplay of neutrophils and natural-killer cells (NK) in mediating osseoresorption during infection of molar-incisor-pattern-periodontitis (MIPP). Human neutrophils from periodontally healthy and MIPP patients were inoculated with the periopathogen Aggregatibacter-actinomycetemcomitans (JP2) and their supernatants were exposed to NK to study their function and osteoclastogenesis promotion. A mouse MIPP model was used to compare disease progression following NK versus neutrophils depletion. The exposure of primary NK to supernatants of neutrophils inoculated with JP2 led to NK cell arrest and activation with enhanced osteoprotegerin expression. Incubation of monocytes with NK led to osteoclastogenesis, whereas NK that were pre-exposed to healthy neutrophil supernatant showed reduced osteoclastogenesis. In mice, NK depletion led to the similar bone phenotype as the neutrophil's depletion highlighting their role on osseoprotection. The present study portrays a key crosstalk between neutrophils and NK cells during JP2 infection as a central mechanism that regulates bone loss.

T cells in abdominal aortic aneurysm: immunomodulation and clinical application

Abdominal aortic aneurysm (AAA) is characterized by inflammatory cell infiltration, extracellular matrix (ECM) degradation, and vascular smooth muscle cell (SMC) dysfunction. The inflammatory cells involved in AAA mainly include immune cells including macrophages, neutrophils, T-lymphocytes and B lymphocytes and endothelial cells. As the blood vessel wall expands, more and more lymphocytes infiltrate into the outer membrane. It was found that more than 50% of lymphocytes in AAA tissues were CD3+ T cells, including CD4+, CD8+T cells, γδ T cells and regulatory T cells (Tregs). Due to the important role of T cells in inflammatory response, an increasing number of researchers have paid attention to the role of T cells in AAA and dug into the relevant mechanism. Therefore, this paper focuses on reviewing the immunoregulatory role of T cells in AAA and their role in immunotherapy, seeking potential targets for immunotherapy and putting forward future research directions.

Micro- and Macrovascular Effects of Inflammation in Peripheral Artery Disease-Pathophysiology and Translational Therapeutic Approaches

Inflammation has a critical role in the development and progression of atherosclerosis. On the molecular level, inflammatory pathways negatively impact endothelial barrier properties and thus, tissue homeostasis. Conformational changes and destruction of the glycocalyx further promote pro-inflammatory pathways also contributing to pro-coagulability and a prothrombotic state. In addition, changes in the extracellular matrix composition lead to (peri-)vascular remodelling and alterations of the vessel wall, e.g., aneurysm formation. Moreover, progressive fibrosis leads to reduced tissue perfusion due to loss of functional capillaries. The present review aims at discussing the molecular and clinical effects of inflammatory processes on the micro- and macrovasculature with a focus on peripheral artery disease.

The perspectives of NETosis on the progression of obesity and obesity-related diseases: mechanisms and applications

Obesity is a disease commonly associated with urbanization and can also be characterized as a systemic, chronic metabolic condition resulting from an imbalance between energy intake and expenditure. The World Health Organization (WHO) has identified obesity as the most serious chronic disease that is increasingly prevalent in the world population. If left untreated, it can lead to dangerous health issues such as hypertension, hyperglycemia, hyperlipidemia, hyperuricemia, nonalcoholic steatohepatitis, atherosclerosis, and vulnerability to cardiovascular and cerebrovascular events. The specific mechanisms by which obesity affects the development of these diseases can be refined to the effect on immune cells. Existing studies have shown that the development of obesity and its associated diseases is closely related to the balance or lack thereof in the number and function of various immune cells, of which neutrophils are the most abundant immune cells in humans, infiltrating and accumulating in the adipose tissues of obese individuals, whereas NETosis, as a newly discovered type of neutrophil-related cell death, its role in the development of obesity and related diseases is increasingly emphasized. The article reviews the significant role that NETosis plays in the development of obesity and related diseases, such as diabetes and its complications. It discusses the epidemiology and negative impacts of obesity, explains the mechanisms of NETosis, and examines its potential as a targeted drug to treat obesity and associated ailments.

Diabetes-associated neutrophil NETosis: pathogenesis and interventional target of diabetic complications

Neutrophil extracellular traps (NETs) are known as extracellular fibers networks consisting of antimicrobial proteins and decondensated chromatin DNA released by activated neutrophils. NETosis is a NETs-induced neutrophilic cell death which is unique from necrosis or apoptosis. Besides its neutralizing pathogen, NETosis plays a crucial role in diabetes and diabetes-related complications. In patients with diabetes, NETs-releasing products are significantly elevated in blood, and these findings confirm the association of NETosis and diabetic complications, including diabetic wound healing, diabetic retinopathy, and atherosclerosis. This article briefly summarizes the mechanisms of NETosis and discusses its contribution to the pathogenesis of diabetes-related complications and suggests new therapeutic targets by some small molecule compounds.

Association Between IL-17 and Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

Background

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease characterized by neutrophils airway infiltration. It is currently known that Interleukin-17 (IL-17) is an important pro-inflammatory factor. It can promote the accumulation of neutrophils and participate in the chronic inflammatory process of COPD. However, the value of IL-17 levels in the diagnosis and assessment of COPD remains controversial. In view of this, we conducted a systematic review and meta-analysis to assess its relevance.

Methods

We searched databases such as PubMed, Web of Science, Cochrane Library and Embase to extract original research.

Results

A total of 10 studies with 2268 participants were included in this meta-analysis. The results showed that the level of serum IL-17 in patients with stable COPD was significantly higher than that in healthy controls (standard mean difference SMD, 1.59, 95% CI 0.84-2.34; p<0.001). Compared with the stable COPD group, the serum IL-17 level in acute exacerbation (AECOPD) was significantly higher (SMD, 1.78, 95% CI 1.22-2.33; p<0.001). The level of IL-17 in sputum of COPD patients was also higher than that of healthy controls (SMD, 2.03, 95% CI 0.74-3.31; p<0.001).

Conclusion

Our results showed that IL-17 levels were elevated in serum and sputum in COPD patients compared with healthy controls, and IL-17 levels increased with disease progression. IL-17 serves as a potential biomarker to indicate the persistence of neutrophilic inflammation and exacerbation of COPD.

Neutrophil extracellular traps contributing to atherosclerosis: From pathophysiology to clinical implications

Neutrophil extracellular traps (NETs) are network-like structures of chromatin filaments decorated by histones, granules, and cytoplasmic-derived proteins expelled by activated neutrophils under multiple pathogenic conditions. NETs not only capture pathogens in innate immunity but also respond to sterile inflammatory stimuli in atherosclerosis, such as lipoproteins and inflammatory cytokines. Atherosclerosis is a lipid-driven chronic inflammatory disease characterized by the accumulation and transformation of inflammatory cells, and smooth muscle cells in the intimal space. NETs-derived extracellular components possess toxic and proinflammatory properties leading to cellular dysfunction and tissue damage, which may establish a link among lipid metabolism, inflammatory immunity, and atherosclerosis. In this review, we discuss recent advances regarding the role of NETs engaged in the pathogenesis of atherosclerosis, particularly focusing on the interaction with lipids and inflammasomes, crosstalk with smooth muscle cells and inflammatory cells, and the association with aging. We also evaluate the current knowledge on the potential of NETs as biomarkers and therapeutic targets for atherosclerosis and its related diseases in clinical practice.

Reduction of neutrophil extracellular traps accelerates inflammatory resolution and increases bone formation on titanium implants

Neutrophils are the most abundant immune cells in the blood and the first cells to be recruited to the biomaterial implantation site. Neutrophils are fundamental in recruiting mononuclear leukocytes to mount an immune response at the injury site. Neutrophils exert significant pro-inflammatory effects through the release of cytokines and chemokines, degranulation and release of myeloperoxidase (MPO) and neutrophil elastase (NE), and the production of large DNA-based networks called neutrophil extracellular traps (NETs). Neutrophils are initially recruited and activated by cytokines and pathogen- and damage-associated molecular patterns, but little is known about how the physicochemical composition of the biomaterial affects their activation. This study aimed to understand how ablating neutrophil mediators (MPO, NE, NETs) affected macrophage phenotype in vitro and osseointegration in vivo. We discovered that NET formation is a crucial mediator of pro-inflammatory macrophage activation, and inhibition of NET formation significantly suppresses macrophage pro-inflammatory phenotype. Furthermore, reducing NET formation accelerated the inflammatory phase of healing and produced greater bone formation around the implanted biomaterial, suggesting that NETs are essential regulators of biomaterial integration. Our findings emphasize the importance of the neutrophil response to implanted biomaterials and highlight innate immune cells' regulation and amplification signaling during the initiation and resolution of the inflammatory phase of biomaterial integration. STATEMENT OF SIGNIFICANCE: Neutrophils are the most abundant immune cells in blood and are the first to be recruited to the injury/implantation site where they exert significant pro-inflammatory effects. This study aimed to understand how ablating neutrophil mediators affected macrophage phenotype in vitro and bone apposition in vivo. We found that NET formation is a crucial mediator of pro-inflammatory macrophage activation. Reducing NET formation accelerated the inflammatory phase of healing and produced greater appositional bone formation around the implanted biomaterial, suggesting that NETs are essential regulators of biomaterial integration.

Role of neutrophils in different stages of atherosclerosis

Neutrophils constitute the first line of defense in human immunity and can be attracted to inflamed and infected sites by various chemokines. As essential players in immune processes, neutrophils theoretically play integral roles in the course of chronic inflammation-induced atherosclerosis. However, because neutrophils are rarely found in atherosclerotic lesions, their involvement in the pathophysiological progression of atherosclerosis has been largely underestimated or ignored. Recent research has revealed convincing evidence showing the presence of neutrophils in atherosclerotic lesions and has revealed neutrophil contributions to different atherosclerosis stages in mice and humans. This review describes the underlying mechanisms of neutrophils in different stages of atherosclerosis and highlights potential neutrophil-targeted therapeutic strategies relevant to atherosclerosis. An in-depth understanding of neutrophils' roles in atherosclerosis pathology will promote exploration of new methods for the prevention and treatment of atherogenesis and atherothrombosis.

Advances in the Mechanism of Action of Neutrophil Extracellular Traps in Gastrointestinal Tumors: A Review

Introduction

Neutrophils are important immune cells in the body, extremely abundant, phagocytic and bactericidal, and usually involved in the defense against infectious diseases as immune become. However, a new reticulum structure has been discovered: neutrophil extracellular traps (NETs), which consists of various components such as DNA and proteins, etc. Current studies have found that NETs are closely associated with various diseases such as immune diseases, inflammation and tumors, and the study of the development and metastasis of gastrointestinal tumors has become a recent research hotspot. The clinical significance of NETs has been gradually highlighted, especially in the area of immunosuppression.

Methods

We reviewed a large amount of relevant literature, summarized the latest detection methods of NETs, explored the mechanism of NETs in gastrointestinal tumors and summarized the latest hotspot directions.

Results

NETs are involved in the development of gastrointestinal tumors, and are closely related to the proliferation and metastasis of gastrointestinal tumors. Higher levels of NETs are associated with poor prognosis of gastrointestinal tumors, promote local growth of tumors through various pathways, participate in tumor-related systemic injury, and promote tumor growth and metastasis by enhancing the mitochondrial function of tumor cells and awakening dormant tumor cells.

Discussion

NETs are highly expressed in tumors, and tumors and their microenvironment can promote the production of NETs, providing new ideas for the clinical diagnosis and treatment of gastrointestinal tumors. In this paper, we describe the basic information about NETs, explore the research mechanisms related to NETs in gastrointestinal tumors, and prospectively explore the clinical potential of hotspots and inhibitors related to NETs for gastrointestinal tumors, in order to provide new ideas and targets for the diagnosis and treatment of gastrointestinal tumors.

Innate immune responses in Behçet disease and relapsing polychondritis

Behçet disease (BD) and relapsing polychondritis (RP) are chronic multisystem disorders characterized by recurrent flare-ups of tissue inflammation. Major clinical manifestations of BD are oral aphthae, genital aphthous ulcers, skin lesions, arthritis, and uveitis. Patients with BD may develop rare but serious neural, intestinal, and vascular complications, with high relapse rates. Meanwhile, RP is characterized by the inflammation of the cartilaginous tissues of the ears, nose, peripheral joints, and tracheobronchial tree. Additionally, it affects the proteoglycan-rich structures in the eyes, inner ear, heart, blood vessels, and kidneys. The mouth and genital ulcers with inflamed cartilage (MAGIC) syndrome is a common characteristic of BD and RP. The immunopathology of these two diseases may be closely related. It is established that the genetic predisposition to BD is related to the human leukocyte antigen (HLA)-B51 gene. Skin histopathology demonstrates the overactivation of innate immunity, such as neutrophilic dermatitis/panniculitis, in patients with BD. Monocytes and neutrophils frequently infiltrate cartilaginous tissues of patients with RP. Somatic mutations in UBA1, which encodes a ubiquitylation-related enzyme, cause vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome (VEXAS) with severe systemic inflammation and activation of myeloid cells. VEXAS prompts auricular and/or nasal chondritis, with neutrophilic infiltration around the cartilage in 52-60% of patients. Thus, innate immune cells may play an important role in the initiation of inflammatory processes underlying both diseases. This review summarizes the recent advances in our understanding of the innate cell-mediated immunopathology of BD and RP, with a focus on the common and distinct features of these mechanisms.

Mechanisms of neutrophil extracellular trap in chronic inflammation of endothelium in atherosclerosis

Cardiovascular diseases are a primary cause of morbidity and mortality around the world. In addition, atherosclerosis (AS)-caused cardiovascular disease is the primary cause of death in human diseases, and almost two billion people suffer from carotid AS worldwide. AS is caused by chronic inflammation of the arterial vessel and is initiated by dysfunction of vascular endothelial cells. Neutrophils protect against pathogen invasion because they function as a component of the innate immune system. However, the contribution of neutrophils to cardiovascular disease has not yet been clarified. Neutrophil extracellular traps (NETs) represent an immune defense mechanism that is different from direct pathogen phagocytosis. NETs are extracellular web-like structures activated by neutrophils, and they play important roles in promoting endothelial inflammation via direct or indirect pathways. NETs consist of DNA, histones, myeloperoxidase, matrix metalloproteinases, proteinase 3, etc. Most of the components of NETs have no direct toxic effect on endothelial cells, such as DNA, but they can damage endothelial cells indirectly. In addition, NETs play a critical role in the process of AS; therefore, it is important to clarify the mechanisms of NETs in AS because NETs are a new potential therapeutic target AS. This review summarizes the possible mechanisms of NETs in AS.

COVID-19 and the cardiovascular system: a study of pathophysiology and interpopulation variability

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in humans can lead to various degrees of tissue and organ damage, of which cardiovascular system diseases are one of the main manifestations, such as myocarditis, myocardial infarction, and arrhythmia, which threaten the infected population worldwide. These diseases threaten the cardiovascular health of infected populations worldwide. Although the prevalence of coronavirus disease 2019 (COVID-19) has slightly improved with virus mutation and population vaccination, chronic infection, post-infection sequelae, and post-infection severe disease patients still exist, and it is still relevant to study the mechanisms linking COVID-19 to cardiovascular disease (CVD). This article introduces the pathophysiological mechanism of COVID-19-mediated cardiovascular disease and analyzes the mechanism and recent progress of the interaction between SARS-CoV-2 and the cardiovascular system from the roles of angiotensin-converting enzyme 2 (ACE2), cellular and molecular mechanisms, endothelial dysfunction, insulin resistance, iron homeostasis imbalance, and psychosocial factors, respectively. We also discussed the differences and mechanisms involved in cardiovascular system diseases combined with neocoronavirus infection in different populations and provided a theoretical basis for better disease prevention and management.

Neutrophil extracellular trap burden correlates with the stenosis of coronary atherosclerosis

Background

Coronary atherosclerosis diseases (CADs) are associated with chronic inflammation. Neutrophil extracellular traps (NETs) are a type of novel proinflammatory cytokines whose levels are dramatically elevated in acute coronary syndrome. We conducted this study to further evaluate the association between circulating NET-associated markers and CAD in Chinese adults.

Methods

A total of 174 patients with CAD and 55 healthy controls were screened using percutaneous coronary intervention or coronary computed tomography angiography. Blood lipid levels, blood glucose levels, and blood cell counts were determined using commercial kits. Serum levels of myeloperoxidase (MPO) and neutrophil elastase (NE) were measured using ELISA. Double-stranded DNA (dsDNA) in serum was quantified using the Quant-iT PicoGreen assay. We also compared the circulating NET levels with various parameters in the study subjects.

Results

The levels of serum NET markers, dsDNA, MPO, and NE, were significantly elevated in patients with CAD, particularly in the severe group, consistent with the increase in neutrophil counts. The levels of NET markers correlated with the risk factors of AS, increasing with the number of risk factors. NET markers were identified as independent risk factors for severe coronary stenosis and also as predictors of severe CAD.

Conclusion

NETs may be related to AS and serve as indicators or predictors of stenosis in patients with severe CAD.

Mapping current status and emerging trends in NETosis: A bibliometric study

BACKGROUND

NETosis is a critical innate immune mechanism of neutrophils that contributes to the accelerated progression of autoimmune diseases, thrombosis, cancer, and coronavirus disease 2019 (COVID-19). This study qualitatively and quantitatively analyzed the relevant literature by bibliometric methods in order to provide a more comprehensive and objective view of the knowledge dynamics in the field.

METHODS

The literature on NETosis was downloaded from the Web of Science Core Collection, analyzed with VOSviewer, CiteSpace, and Microsoft for co-authorship, co-occurrence, and co-citation analysis.

RESULTS

In the field of NETosis, the United States was the most influential countries. Harvard University was the most active institutions. Mariana J. Kaplan and Brinkmann V were, respectively, the most prolific and most co-cited authors. Frontiers in Immunology, Journal of Immunology, Plos One, Blood, Science, Journal of Cell Biology, and Nature Medicine were the most influential journals. The top 15 keywords are associated with immunological and NETosis formation mechanisms. The keywords with the strongest burst detection were mainly related to COVID-19 (coronavirus, ACE2, SARS coronavirus, cytokine storm, pneumonia, neutrophil to lymphocyte ratio), and cancer (circulating tumor cell).

CONCLUSION

Research on NETosis is currently booming. The mechanism of NETosis and its role in innate immunity, autoimmune diseases, especially systemic lupus erythematosus and rheumatoid arthritis, and thrombosis are the focus of research in the field of NETosis. A future study will concentrate on the function of NETosis in COVID-19 and recurrent metastasis of cancer.

Inflammasomes and Atherosclerosis: a Mixed Picture

The CANTOS (Canakinumab Anti-inflammatory Thrombosis Outcome Study) and colchicine trials suggest an important role of inflammasomes and their major product IL-1β (interleukin 1β) in human atherosclerotic cardiovascular disease. Moreover, studies in mouse models indicate a causal role of inflammasomes and IL-1β in atherosclerosis. However, recent studies have led to a more granular view of the role of inflammasomes in atherosclerosis. Studies in hyperlipidemic mouse models suggest that prominent activation of the NLRP3 inflammasome requires a second hit such as defective cholesterol efflux, defective DNA repair, clonal hematopoiesis or diabetes. Similarly in humans some mutations promoting clonal hematopoiesis increase coronary artery disease risk in part by promoting inflammasome activation. Recent studies in mice and humans point to a wider role of the AIM2 (absent in melanoma 2) inflammasome in promoting cardiovascular disease including in some forms of clonal hematopoiesis and diabetes. These developments suggest a precision medicine approach in which treatments targeting inflammasomes or IL-1β might be best employed in clinical settings involving increased inflammasome activation.

NET-(works) in arterial and venous thrombo-occlusive diseases

Formation of Neutrophil Extracellular Traps (NETosis), accompanied by the release of extracellular decondensed chromatin and pro-inflammatory as well as pro-thrombotic factors, is a pivotal element in the development and progression of thrombo-occlusive diseases. While the process of NETosis is based on complex intracellular signalling mechanisms, it impacts a wide variety of cells including platelets, leukocytes and endothelial cells. Consequently, although initially mainly associated with venous thromboembolism, NETs also affect and mediate atherothrombosis and its acute complications in the coronary, cerebral and peripheral arterial vasculature. In this context, besides deep vein thrombosis and pulmonary embolism, NETs in atherosclerosis and especially its acute complications such as myocardial infarction and ischemic stroke gained a lot of attention in the cardiovascular research field in the last decade. Thus, since the effect of NETosis on platelets and thrombosis in general is extensively discussed in other review articles, this review focusses on the translational and clinical relevance of NETosis research in cardiovascular thrombo-occlusive diseases. Consequently, after a brief summary of the neutrophil physiology and the cellular and molecular mechanisms underlying NETosis are presented, the role of NETosis in atherosclerotic and venous thrombo-occlusive diseases in chronic and acute settings are discussed. Finally, potential prevention and treatment strategies of NET-associated thrombo-occlusive diseases are considered.

Neutrophil extracellular traps in acute coronary syndrome

Acute coronary syndrome (ACS) is a group of clinical syndromes caused by acute myocardial ischemia, which can cause heart failure, arrhythmia and even sudden death. It is the major cause of disability and death worldwide. Neutrophil extracellular traps (NETs) are reticular structures released by neutrophils activation and have various biological functions. NETs are closely related to the occurrence and development of ACS and also the subsequent damage after myocardial infarction. The mechanisms are complex and interdependent on various pathways, which require further exploration. This article reviewed the role and mechanism of NETs in ACS, thereby providing a valuable reference for the diagnosis and clinical treatment of ACS.

Neutrophil metabolomics in severe COVID-19 reveal GAPDH as a suppressor of neutrophil extracellular trap formation

Severe COVID-19 is characterized by an increase in the number and changes in the function of innate immune cells including neutrophils. However, it is not known how the metabolome of immune cells changes in patients with COVID-19. To address these questions, we analyzed the metabolome of neutrophils from patients with severe or mild COVID-19 and healthy controls. We identified widespread dysregulation of neutrophil metabolism with disease progression including in amino acid, redox, and central carbon metabolism. Metabolic changes in neutrophils from patients with severe COVID-19 were consistent with reduced activity of the glycolytic enzyme GAPDH. Inhibition of GAPDH blocked glycolysis and promoted pentose phosphate pathway activity but blunted the neutrophil respiratory burst. Inhibition of GAPDH was sufficient to cause neutrophil extracellular trap (NET) formation which required neutrophil elastase activity. GAPDH inhibition increased neutrophil pH, and blocking this increase prevented cell death and NET formation. These findings indicate that neutrophils in severe COVID-19 have an aberrant metabolism which can contribute to their dysfunction. Our work also shows that NET formation, a pathogenic feature of many inflammatory diseases, is actively suppressed in neutrophils by a cell-intrinsic mechanism controlled by GAPDH.

Cholesterol accumulation in macrophages drives NETosis in atherosclerotic plaques via IL-1β secretion

AIMS

Neutrophil extracellular trap formation (NETosis) increases atherosclerotic plaque vulnerability and athero-thrombosis. However, mechanisms promoting NETosis during atherogenesis are poorly understood. We have shown that cholesterol accumulation due to myeloid cell deficiency of the cholesterol transporters ATP Binding Cassette A1 and G1 (ABCA1/G1) promotes NLRP3 inflammasome activation in macrophages and neutrophils and induces prominent NETosis in atherosclerotic plaques. We investigated whether NETosis is a cell-intrinsic effect in neutrophils or is mediated indirectly by cellular crosstalk from macrophages to neutrophils involving IL-1β.

METHODS AND RESULTS

We generated mice with neutrophil or macrophage-specific Abca1/g1 deficiency (S100A8CreAbca1fl/flAbcg1fl/fl or CX3CR1CreAbca1fl/flAbcg1fl/fl mice, respectively), and transplanted their bone marrow into low-density lipoprotein receptor knockout mice. We then fed the mice a cholesterol-rich diet. Macrophage, but not neutrophil Abca1/g1 deficiency activated inflammasomes in macrophages and neutrophils, reflected by caspase-1 cleavage, and induced NETosis in plaques. NETosis was suppressed by administering an interleukin (IL)-1β neutralizing antibody. The extent of NETosis in plaques correlated strongly with the degree of neutrophil accumulation, irrespective of blood neutrophil counts, and neutrophil accumulation was decreased by IL-1β antagonism. In vitro, IL-1β or media transferred from Abca1/g1-deficient macrophages increased NETosis in both control and Abca1/Abcg1 deficient neutrophils. This cell-extrinsic effect of IL-1β on NETosis was blocked by an NLRP3 inhibitor.

CONCLUSION

These studies establish a new link between inflammasome-mediated IL-1β production in macrophages and NETosis in atherosclerotic plaques. Macrophage-derived IL-1β appears to increase NETosis both by increasing neutrophil recruitment to plaques and by promoting neutrophil NLRP3 inflammasome activation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Immune cell response to orthopedic and craniofacial biomaterials depends on biomaterial composition

Materials for craniofacial and orthopedic implants are commonly selected based on mechanical properties and corrosion resistance. The biocompatibility of these materials is typically assessed in vitro using cell lines, but little is known about the response of immune cells to these materials. This study aimed to evaluate the inflammatory and immune cell response to four common orthopedic materials [pure titanium (Ti), titanium alloy (TiAlV), 316L stainless steel (SS), polyetheretherketone (PEEK)]. Following implantation into mice, we found high recruitment of neutrophils, pro-inflammatory macrophages, and CD4+ T cells in response to PEEK and SS implants. Neutrophils produced higher levels of neutrophil elastase, myeloperoxidase, and neutrophil extracellular traps in vitro in response to PEEK and SS than neutrophils on Ti or TiAlV. Macrophages co-cultured on PEEK, SS, or TiAlV increased polarization of T cells towards Th1/Th17 subsets and decreased Th2/Treg polarization compared to Ti substrates. Although SS and PEEK are considered biocompatible materials, both induce a more robust inflammatory response than Ti or Ti alloy characterized by high infiltration of neutrophils and T cells, which may cause fibrous encapsulation of these materials. STATEMENT OF SIGNIFICANCE: Materials for craniofacial and orthopedic implants are commonly selected based on their mechanical properties and corrosion resistance. This study aimed to evaluate the immune cell response to four common orthopedic and craniofacial biomaterials: pure titanium, titanium-aluminum-vanadium alloy, 316L stainless steel, and PEEK. Our results demonstrate that while the biomaterials tested have been shown to be biocompatible and clinically successful, the inflammatory response is largely driven by chemical composition of the biomaterials.

Polyunsaturated fatty acids drive neutrophil extracellular trap formation in nonalcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is the hepatic manifestation of metabolic syndrome. Non-resolving inflammation, triggered by sustained accumulation of lipids, is an important driving force of NASH. Thus, unveiling metabolic immune regulation could help better understand the pathology and intervention of NASH. In this study, we found the recruitment of neutrophils is an early inflammatory event in NASH mice, following the formation of neutrophil extracellular traps (NETs). NET is an initiating factor which exacerbates inflammatory responses in macrophages. Inhibition of NETs using DNase I significantly alleviated inflammation in NASH mice. We further carried out a metabolomic study to identify possible metabolic triggers of NETs, and linoleic acid (LA) metabolic pathway was the most altered pathway. We re-analyzed published clinical data and validated that LA metabolism was highly correlated with NASH. Consistently, both LA and γ-linolenic acid (GLA) were active in triggering NETs formation by oxidative burst. Furthermore, we identified silybin, a hepatoprotective agent, as a potent NETosis inhibitor, which effectively blocked NETs formation both in vitro and in vivo. Together, this study not only provide new insights into metabolism-immune causal link in NASH progression, but also demonstrate silybin as an important inhibitor of NETs and its therapeutical potential in treating NETosis-related diseases.

New Insights into Pathophysiology and New Risk Factors for ACS

Cardiovascular disease still represents the main cause of mortality worldwide. Despite huge improvements, atherosclerosis persists as the principal pathological condition, both in stable and acute presentation. Specifically, acute coronary syndromes have received substantial research and clinical attention in recent years, contributing to improve overall patients' outcome. The identification of different evolution patterns of the atherosclerotic plaque and coronary artery disease has suggested the potential need of different treatment approaches, according to the mechanisms and molecular elements involved. In addition to traditional risk factors, the finer portrayal of other metabolic and lipid-related mediators has led to higher and deep knowledge of atherosclerosis, providing potential new targets for clinical management of the patients. Finally, the impressive advances in genetics and non-coding RNAs have opened a wide field of research both on pathophysiology and the therapeutic side that are extensively under investigation.

Colchicine exerts anti-atherosclerotic and -plaque-stabilizing effects targeting foam cell formation

Colchicine is a broad-acting anti-inflammatory agent that has attracted interest for repurposing in atherosclerotic cardiovascular disease. Here, we studied its ability at a human equivalent dose of 0.5 mg/day to modify plaque formation and composition in murine atherosclerosis and investigated its actions on macrophage responses to atherogenic stimuli in vitro. In atherosclerosis induced by high-cholesterol diet, Apoe^-/- mice treated with colchicine had 50% reduction in aortic oil Red O⁺ plaque area compared to saline control (p = .001) and lower oil Red O⁺ staining of aortic sinus lesions (p = .03). In vitro, addition of 10 nM colchicine inhibited foam cell formation from murine and human macrophages after treatment with oxidized LDL (ox-LDL). Mechanistically, colchicine downregulated glycosylation and surface expression of the ox-LDL uptake receptor, CD36, and reduced CD36⁺ staining in aortic sinus plaques. It also decreased macrophage uptake of cholesterol crystals, resulting in lower intracellular lysosomal activity, inhibition of the NLRP3 inflammasome, and reduced secretion of IL-1β and IL-18. Colchicine's anti-atherosclerotic actions were accentuated in a mouse model of unstable plaque induced by carotid artery tandem stenosis surgery, where it decreased lesion size by 48% (p = .01), reduced lipid (p = .006) and necrotic core area (p = .007), increased collagen content and cap-to-necrotic core ratio (p = .05), and attenuated plaque neutrophil extracellular traps (p < .001). At low dose, colchicine's effects were not accompanied by the evidence of microtubule depolymerization. Together, these results show that colchicine exerts anti-atherosclerotic and plaque-stabilizing effects at low dose by inhibiting foam cell formation and cholesterol crystal-induced inflammation. This provides a new framework to support its repurposing for atherosclerotic cardiovascular disease.

Artificial Intelligence in Symptomatic Carotid Plaque Detection: A Narrative Review

Identifying atherosclerotic disease is the mainstay for the correct diagnosis of the large artery atherosclerosis ischemic stroke subtype and for choosing the right therapeutic strategy in acute ischemic stroke. Classification into symptomatic and asymptomatic plaque and estimation of the cardiovascular risk are essential to select patients eligible for pharmacological and/or surgical therapy in order to prevent future cerebral ischemic events. The difficulties in a “vulnerability” definition and the methodical issues concerning its detectability and quantification are still subjects of debate. Non-invasive imaging studies commonly used to detect arterial plaque are computed tomographic angiography, magnetic resonance imaging, and ultrasound. Characterization of a carotid plaque type using the abovementioned imaging modalities represents the basis for carotid atherosclerosis management. Classification into symptomatic and asymptomatic plaque and estimation of the cardiovascular risk are essential to select patients eligible for pharmacological and/or surgical therapy in order to prevent future cerebral ischemic events. In this setting, artificial intelligence (AI) can offer suggestive solutions for tissue characterization and classification concerning carotid artery plaque imaging by analyzing complex data and using automated algorithms to obtain a final output. The aim of this review is to provide overall knowledge about the role of AI models applied to non-invasive imaging studies for the detection of symptomatic and vulnerable carotid plaques.

Neutrophil extracellular traps contribute to coagulopathy after traumatic brain injury

Coagulopathy contributes to the majority of deaths and disabilities associated with traumatic brain injury (TBI). Whether neutrophil extracellular traps (NETs) contribute to an abnormal coagulation state in the acute phase of TBI remains unknown. Our objectives were to demonstrate the definitive role of NETs in coagulopathy in TBI. We detected NET markers in 128 TBI patients and 34 healthy individuals. Neutrophil-platelet aggregates were detected in blood samples from TBI patients and healthy individuals using flow cytometry and staining for CD41 and CD66b. Endothelial cells were incubated with isolated NETs and we detected the expression of vascular endothelial cadherin, syndecan-1, thrombomodulin, von Willebrand factor, phosphatidylserine, and tissue factor. In addition, we established a TBI mouse model to determine the potential role of NETs in TBI-associated coagulopathy. NET generation was mediated by high mobility group box 1 (HMGB1) from activated platelets and contributed to procoagulant activity in TBI. Furthermore, coculture experiments indicated that NETs damaged the endothelial barrier and caused these cells to assume a procoagulant phenotype. Moreover, the administration of DNase I before or after brain trauma markedly reduced coagulopathy and improved the survival and clinical outcome of mice with TBI.

NETworking with cancer: The bidirectional interplay between cancer and neutrophil extracellular traps

Neutrophils are major effectors and regulators of the immune system. They play critical roles not only in the eradication of pathogens but also in cancer initiation and progression. Conversely, the presence of cancer affects neutrophil activity, maturation, and lifespan. By promoting or repressing key neutrophil functions, cancer cells co-opt neutrophil biology to their advantage. This co-opting includes hijacking one of neutrophils' most striking pathogen defense mechanisms: the formation of neutrophil extracellular traps (NETs). NETs are web-like filamentous extracellular structures of DNA, histones, and cytotoxic granule-derived proteins. Here, we discuss the bidirectional interplay by which cancer stimulates NET formation, and NETs in turn support disease progression. We review how vascular dysfunction and thrombosis caused by neutrophils and NETs underlie an elevated risk of death from cardiovascular events in cancer patients. Finally, we propose therapeutic strategies that may be effective in targeting NETs in the clinical setting.

Neutrophil extracellular traps in tumor progression and immunotherapy

Tumor immunity is a growing field of research that involves immune cells within the tumor microenvironment. Neutrophil extracellular traps (NETs) are neutrophil-derived extracellular web-like chromatin structures that are composed of histones and granule proteins. Initially discovered as the predominant host defense against pathogens, NETs have attracted increasing attention due to they have also been tightly associated with tumor. Excessive NET formation has been linked to increased tumor growth, metastasis, and drug resistance. Moreover, through direct and/or indirect effects on immune cells, an abnormal increase in NETs benefits immune exclusion and inhibits T-cell mediated antitumor immune responses. In this review, we summarize the recent but rapid progress in understanding the pivotal roles of NETs in tumor and anti-tumor immunity, highlighting the most relevant challenges in the field. We believe that NETs may be a promising therapeutic target for tumor immunotherapy.

Prognostic impact of white blood cell counts on clinical outcomes in patients with chronic renal insufficiency undergoing percutaneous coronary intervention

Objective

To determine whether the inclusion of white blood cell (WBC) counts in the SYNTAX score (SS) or SS II models could improve the models’ performance for risk stratification in individuals with chronic renal insufficiency (CRI) following percutaneous coronary intervention (PCI).

Methods

In total, 2,313 patients with CRI, who were subjected to PCI and had data available on in-hospital WBC (ih-WBC) counts, were recruited. Patients were divided into 3 groups as per their ih-WBC counts (low, medium, and high). The primary endpoints were all-cause mortality (ACM) and cardiac mortality (CM). The secondary endpoints incorporated myocardial infarction, stroke, unplanned revascularization, and major adverse cardiovascular and cerebrovascular events (MACCEs).

Results

During a median follow-up of 3 years, the high WBC group had the highest incidences of CM (2.4% vs. 2.1% vs. 6.7%; p &lt; 0.001), ACM (6.3% vs. 4.1% vs. 8.2%; p &lt; 0.001), unplanned revascularization (8.4% vs. 12.4% vs. 14.1%; p &lt; 0.001), and MACCEs (19.3% vs. 23.0% vs. 29.2%; p &lt; 0.001) among the three groups. Multivariable Cox regression analysis depicted that the risk of ACM and CM in the high WBC group was 2.577 (95% confidence interval [CI]: 1.504–4.415, p &lt; 0.001) and 3.850 (95% CI: 1.835–8.080, p &lt; 0.001) times that in the low WBC group after adjusting for other confounding factors. A combination of ih-WBC counts with SS or SS II significantly improved the risk assessment and prediction of ACM and CM.

Conclusion

The ih-WBC counts was associated with the risk of occurrence of ACM, CM, unplanned revascularization, and MACCEs in individuals with CRI following PCI. It provides an incremental predictive value for the occurrence of ACM and CM when included in SS or SS II models.

The impact of neutrophil extracellular traps in coronavirus disease - 2019 pathophysiology

Coronavirus disease 2019 (COVID-19), which is caused by novel coronavirus-2019 (nCoV-2019), is a highly contagious disease with high mortality and morbidity risk. Infected people may suffer from respiratory infections, which may be more progressive in patients with a defective immune system and underlying medical problems. In this regard, the cells involved in the innate immune system, play a decisive role in disease progression and complication development. Pathogen entrapment is the critical role of neutrophil extracellular traps (NETosis). This process involves the widespread release of fibrous structures by the stimulant-activated neutrophils. These fibrous structures are composed of cytosolic proteins and granular contents brought together by a network of released chromatins. This network can inhibit the spread of pathogens by their entrapment. Moreover, NETosis damage the host by producing toxic agents and triggering thrombosis. Therefore, this phenomenon may act as a double-edged sword. Regarding the rapid expansion of COVID-19, it is crucial to examine the involvement of NETosis in infected patients. This study aims to discuss NETosis participation to show its probable association with increased risk of thrombogenicity and help develop new therapeutic approaches in the battle against this viral disease.

PET/MR imaging of inflammation in atherosclerosis

Myocardial infarction, stroke, mental disorders, neurodegenerative processes, autoimmune diseases, cancer and the human immunodeficiency virus impact the haematopoietic system, which through immunity and inflammation may aggravate pre-existing atherosclerosis. The interplay between the haematopoietic system and its modulation of atherosclerosis has been studied by imaging the cardiovascular system and the activation of haematopoietic organs via scanners integrating positron emission tomography and resonance imaging (PET/MRI). In this Perspective, we review the applicability of integrated whole-body PET/MRI for the study of immune-mediated phenomena associated with haematopoietic activity and cardiovascular disease, and discuss the translational opportunities and challenges of the technology.

Neutrophil intrinsic and extrinsic regulation of NETosis in health and disease

Neutrophil extracellular traps (NETs) evolved to protect the host against microbial infections and are formed by a web-like structure of DNA that is decorated with antimicrobial effectors. Due to their potent inflammatory functions, NETs also cause tissue damage and can favor and/or aggravate inflammatory diseases. This multipronged activity of NETs requires that the induction, release, and degradation of NETs are tightly regulated. Here we describe the key pathways that are intrinsic to neutrophils and regulate NETosis, and we review the most recent findings on how neutrophil extrinsic factors participate in the formation of NETs. In particular, we emphasize how bystander cells contribute to modifying the capacity of neutrophils to undergo NETosis. Finally, we discuss how these neutrophil extrinsic processes can be harnessed to protect the host against the excessive inflammation elicited by uncontrolled NET release.

Putative Role of Neutrophil Extracellular Trap Formation in Chronic Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are hematologic malignancies characterized by gene mutations that promote myeloproliferation and resistance to apoptosis via constitutively active signaling pathways, with Janus kinase 2-signal transducers and the activators of transcription (JAK-STAT) axis as a core part. Chronic inflammation has been described as a pivot for the development and advancement of MPNs from early stage cancer to pronounced bone marrow fibrosis, but there are still unresolved questions regarding this issue. The MPN neutrophils are characterized by upregulation of JAK target genes, they are in a state of activation and with deregulated apoptotic machinery. Deregulated neutrophil apoptotic cell death supports inflammation and steers them towards secondary necrosis or neutrophil extracellular trap (NET) formation, a trigger of inflammation both ways. NETs in proinflammatory bone marrow microenvironment induce hematopoietic precursor proliferation, which has an impact on hematopoietic disorders. In MPNs, neutrophils are primed for NET formation, and even though it seems obvious for NETs to intervene in the disease progression by supporting inflammation, no reliable data are available. We discuss in this review the potential pathophysiological relevance of NET formation in MPNs, with the intention of contributing to a better understanding of how neutrophils and neutrophil clonality can orchestrate the evolution of a pathological microenvironment in MPNs.

Relationship between Cholesterol-Related Lipids and Severe Acute Pancreatitis: From Bench to Bedside

It is well known that hypercholesterolemia in the body has pro-inflammatory effects through the formation of inflammasomes and augmentation of TLR (Toll-like receptor) signaling, which gives rise to cardiovascular disease and neurodegenerative diseases. However, the interaction between cholesterol-related lipids and acute pancreatitis (AP) has not yet been summarized before. This hinders the consensus on the existence and clinical importance of cholesterol-associated AP. This review focuses on the possible interaction between AP and cholesterol-related lipids, which include total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and apolipoprotein (Apo) A1, from the bench to the bedside. With a higher serum level of total cholesterol, LDL-C is associated with the severity of AP, while the persistent inflammation of AP is allied with a decrease in serum levels of cholesterol-related lipids. Therefore, an interaction between cholesterol-related lipids and AP is postulated. Cholesterol-related lipids should be recommended as risk factors and early predictors for measuring the severity of AP. Cholesterol-lowering drugs may play a role in the treatment and prevention of AP with hypercholesterolemia.

Transient receptor potential melastatin 2 regulates neutrophil extracellular traps formation and delays resolution of neutrophil-driven sterile inflammation

The formation of neutrophil extracellular traps (NETs) is a process releasing into the extracellular space networks of chromatin fibers decorated with granular proteins. It is implicated in infection-related as well as sterile inflammation. Monosodium urate (MSU) crystals serve as damage-associated molecular pattern (DAMP) in various conditions of disease. Formation of NETs or aggregated NETs (aggNETs) orchestrates initiation and resolution of MSU crystals-triggered inflammation, respectively. Elevated intracellular calcium levels and the generation of reactive oxygen species (ROS) are crucial for the formation of MSU crystal-induced NETs. However, the exact signaling pathways involved are still elusive. Herein, we demonstrate that the ROS-sensing, non-selective calcium-permeable channel transient receptor potential cation channel subfamily M member 2 (TRPM2) is required for a full-blown MSU crystal-induced NET formation. Primary neutrophils from TRPM2^-/- mice showed reduced calcium influx and ROS production and, consequently a reduced formation of MSU crystal-induced NETs and aggNETs. Furthermore, in TRPM2^-/- mice the infiltration of inflammatory cells into infected tissues and their production of inflammatory mediators was suppressed. Taken together these results describe an inflammatory role of TRPM2 for neutrophil-driven inflammation and identify TRPM2 as potential target for therapeutic intervention.

Analysis of the Genetic Relationship between Atherosclerosis and Non-Alcoholic Fatty Liver Disease through Biological Interaction Networks

Non-alcoholic fatty liver disease (NAFLD) seems to have some molecular links with atherosclerosis (ATH); however, the molecular pathways which connect both pathologies remain unexplored to date. The identification of common factors is of great interest to explore some therapeutic strategies to improve the outcomes for those affected patients. Differentially expressed genes (DEGs) for NAFLD and ATH were extracted from the GSE89632 and GSE100927 datasets, and common up- and downregulated DEGs were identified. Subsequently, a protein-protein interaction (PPI) network based on the common DEGs was performed. Functional modules were identified, and the hub genes were extracted. Then, a Gene Ontology (GO) and pathway analysis of common DEGs was performed. DEGs analysis in NAFLD and ATH showed 21 genes that were regulated similarly in both pathologies. The common DEGs with high centrality scores were ADAMTS1 and CEBPA which appeared to be down- and up-regulated in both disorders, respectively. For the analysis of functional modules, two modules were identified. The first one was oriented to post-translational protein modification, where ADAMTS1 and ADAMTS4 were identified, and the second one mainly related to the immune response, where CSF3 was identified. These factors could be key proteins with an important role in the NAFLD/ATH axis.

Nanoparticulate Cationic Poly(amino acid)s Block Cancer Metastases by Destructing Neutrophil Extracellular Traps

Cancer metastasis that is resistant to conventional therapies has become a major cause of patient death. Recent reports indicate that the neutrophil extracellular trap (NET) is closely associated with cancer distant metastases, and the cell-free DNA of NETs has been identified as the ligand of the transmembrane protein CCDC25 of cancer cells, acting as a chemokine to induce cancer cell migration to distant organs. In this work, we present the poly(aspartic acid) based-cationic materials to interfere with the interaction between NET-DNA and CCDC25, and furthermore to inhibit NET-DNA-mediated cancer cell chemotaxis and migration. Because of a stronger binding affinity to DNA and favorable retention in the liver, nanoparticulate poly(aspartic acid) derivatives (cANP) efficiently reduce the level of hepatic NET-DNA infiltration, leading to a significant suppression of cancer metastases in mice and several human metastatic models. Moreover, the cANP exhibits no toxicity to organs of animals during the entire treatment. Thus, this work suggests a strategy for controlling cancer metastases, which will benefit patients in clinics.

THE ROLE OF NEUTROPHIL EXTRACELLULAR TRAPS (NETS) IN THE IMMUNOPATHOGENESIS OF SEVERE COVID-19: POTENTIAL IMMUNOTHERAPEUTIC STRATEGIES REGULATING NET FORMATION AND ACTIVITY

The role of neutrophil granulocytes (NG) in the pathogenesis of COVID-19 is associated with the recruitment of NG into inflammatory foci, activation of their functions and enhanced formation of neutrophil extracellular networks (NETs). In this review, we analyzed a fairly large volume of scientific literature devoted to the peculiarities of the formation of NETs, their role in the pathogenesis of COVID-19, participation in the occurrence of immunothrombosis, vasculitis, acute respiratory distress syndrome, cytokine storm syndrome, multi-organ lesions. Convincing data are presented that clearly indicate the significant involvement of NETs in the immunopathogenesis of COVID-19 and the associated severe complications resulting from the intensification of the inflammation process, which is key for the course of infection caused by the SARS-CoV-2 virus. The presented role of NG and NETs, along with the role of other immune system cells and pro-inflammatory cytokines, is extremely important in understanding the development of an overactive immune response in severe COVID-19. The obtained scientific results, available today, allow identifying the possibilities of regulatory effects on hyperactivated NG, on the formation of NETs at various stages and on limiting the negative impact of already formed NETs on various tissues and organs. All of the above should help in the creation of new, specialized immunotherapy strategies designed to increase the chances of survival, reduce the severity of clinical manifestations in patients with COVID-19, as well as significantly reduce mortality rates. Currently, it is possible to use existing drugs and a number of new drugs are being developed, the action of which can regulate the amount of NG, positively affect the functions of NG and limit the intensity of NETs formation. Continuing research on the role of hyperactive NG and netosis, as well as understanding the mechanisms of regulation of the phenomenon of formation and restriction of NETs activity in severe COVID-19, apparently, are a priority, since in the future the new data obtained could become the basis for the development of targeted approaches not only to immunotherapy aimed at limiting education and blocking negative effects already formed NETs in severe COVID-19, but also to immunotherapy, which could be used in the complex treatment of other netopathies, first of all, autoimmune diseases, auto-inflammatory syndromes, severe purulent-inflammatory processes, including bacterial sepsis and hematogenous osteomyelitis.

Emerging Targets for Modulation of Immune Response and Inflammation in Stroke

The inflammatory and immunological responses play a significant role after stroke. The innate immune activation stimulated by microglia during stroke results in the migration of macrophages and lymphocytes into the brain and are responsible for tissue damage. The immune response and inflammation following stroke have no defined targets, and the intricacies of the immunological and inflammatory processes are only partially understood. Innate immune cells enter the brain and meninges during the acute phase, which can cause ischemia damage. Activation of systemic immunity is caused by danger signals sent into the bloodstream by injured brain cells, which is followed by a significant immunodepression that encourages life-threatening infections. Neuropsychiatric sequelae, a major source of post-stroke morbidity, may be induced by an adaptive immune response that is initiated by antigen presentation during the chronic period and is directed against the brain. Thus, the current review discusses the role of immune response and inflammation in stroke pathogenesis, their role in the progression of injury during the stroke, and the emerging targets for the modulation of the mechanism of immune response and inflammation that may have possible therapeutic benefits against stroke.

Blood Count-Derived Inflammatory Markers and Acute Complications of Ischemic Heart Disease in Elderly Women

Coronary artery disease (CAD) in women occurs later than in men. Underlying atherosclerosis, a chronic process of lipoprotein deposition in arterial walls with a prominent inflammatory component, is influenced by several risk factors. In women, commonly used inflammatory markers are generally found to be related to the occurrence of acute coronary syndrome (ACS), as well as the development of other diseases that influence CAD. New inflammatory markers derived from total blood count-systemic inflammatory response index (SII), systemic inflammatory reaction index (SIRI), monocyte-lymphocyte ratio (MLR), platelet-lymphocyte ratio (PLR), and neutrophil-lymphocyte ratio (NLR)-were analyzed in the group of 244 elderly, postmenopausal women with the diagnosis of ACS or stable CAD. SII, SIRI, MLR, and NLR were significantly higher in women with ACS compared to those with stable CAD (p < 0.05 for all)-the highest values were observed in women with NSTEMI. MLR from new inflammatory markers, HDL, and history of MI turned out to be significant factors associated with ACS. These results suggest that MLR as representative of blood count-derived inflammatory markers may be considered as additional CVD risk factors in women with suspected ACS.

White blood cells and coronary heart disease: A mendelian randomization study

Background: The causal direction and magnitude of the associations between blood cell count and coronary heart disease (CHD) remain uncertain due to susceptibility of reverse causation and confounding. This study aimed to investigate the associations between blood cell count and CHD using Mendelian randomization (MR). Methods: In this two-sample MR study, we identified independent blood cell count associated genetic variants from a genome-wide association studies (GWAS) among European ancestry individuals. Summary level data of CHD was obtained from a GWAS consisting of 547261 subjects. Methods of inverse variance weighted (IVW), Mendelian Randomization-Egger (MR-Egger), weighted median, and outlier test (MR-PRESSO) were conducted to investigate the associations between blood cell and CHD. Results: Among all cardiovascular outcomes of interest, blood cell counts were only associated with CHD. Our findings indicated that white blood cell count and neutrophil cell count were significantly associated with increased risk of CHD [odds ratio (OR) = 1.07, 95% confidence interval (CI), 1.01-1.14; OR = 1.09, 1.02-1.16). However, there was no significant association between monocyte cell count, basophil cell count, lymphocyte cell count, eosinophil cell count, and CHD (p > 0.05). The results after excluding outliers were consistent with main results and the sensitivity analyses showed no evidence of pleiotropy (MR-Egger intercept, p > 0.05). Conclusion: Our MR study suggested that greater white blood cell count and neutrophil cell count were associated with a higher risk of CHD. Future studies are still warranted to validate the results and investigate the mechanisms underlying these associations.

The NLRP3 inflammasome fires up heme-induced inflammation in hemolytic conditions

Overactive inflammatory responses are central to the pathophysiology of many hemolytic conditions including sickle cell disease. Excessive hemolysis leads to elevated serum levels of heme due to saturation of heme scavenging mechanisms. Extracellular heme has been shown to activate the NLRP3 inflammasome, leading to activation of caspase-1 and release of pro-inflammatory cytokines IL-1β and IL-18. Heme also activates the non-canonical inflammasome pathway, which may contribute to NLRP3 inflammasome formation and leads to pyroptosis, a type of inflammatory cell death. Some clinical studies indicate there is a benefit to blocking the NLRP3 inflammasome pathway in patients with sickle cell disease and other hemolytic conditions. However, a thorough understanding of the mechanisms of heme-induced inflammasome activation is needed to fully leverage this pathway for clinical benefit. This review will explore the mechanisms of heme-induced NLRP3 inflammasome activation and the role of this pathway in hemolytic conditions including sickle cell disease.

Neutrophil CEACAM1 determines susceptibility to NETosis by regulating the S1PR2/S1PR3 axis in liver transplantation

Neutrophils, the largest innate immune cell population in humans, are the primary proinflammatory sentinel in the ischemia-reperfusion injury (IRI) mechanism in orthotopic liver transplantation (OLT). Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1, CC1, or CD66a) is essential in neutrophil activation and serves as a checkpoint regulator of innate immune-driven IRI cascade in OLT. Although CC1 alternative splicing generates two functionally distinct short and long cytoplasmic isoforms, their role in neutrophil activation remains unknown. Here, we undertook molecular and functional studies to interrogate the significance of neutrophil CC1 signaling in mouse and human OLT recipients. In the experimental arm, we employed a mouse OLT model to document that ablation of recipient-derived neutrophil CC1-long (CC1-L) isotype aggravated hepatic IRI by promoting neutrophil extracellular traps (NETs). Notably, by regulating the S1P-S1PR2/S1PR3 axis, neutrophil CC1-L determined susceptibility to NET formation via autophagy signaling. In the clinical arm, liver grafts from 55 transplant patients selectively enriched for neutrophil CC1-L showed relative resistance to ischemia-reperfusion (IR) stress/tissue damage, improved hepatocellular function, and clinical outcomes. In conclusion, despite neutrophils being considered a principal villain in peritransplant tissue injury, their CC1-L isoform may serve as a regulator of IR stress resistance/NETosis in human and mouse OLT recipients.

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.

Exploratory Study of Serum Lactoferrin and Anti-Lactoferrin Antibody Concentrations in Patients with Endometriosis

Endometriosis is a disease that is characterized by the ectopic presence of the endometrium or its similar cells. A high prevalence of patients with autoimmune diseases has been reported among patients with endometriosis although the cause of endometriosis remained unknown. Recently, the anti-lactoferrin antibody is reported to be highly detected in autoimmune diseases. This study focused on lactoferrin and anti-lactoferrin antibodies to explore the pathology of endometriosis. Lactoferrin is a substance that regulates inflammation and is produced by neutrophils. Anti-lactoferrin antibody is a type of perinuclear antineutrophil cytoplasmic antibody. The serum lactoferrin and anti-lactoferrin antibody levels were compared among patients with or without endometriosis, revealing significantly higher levels in patients with endometriosis. Additionally, a decreased serum anti-lactoferrin antibody level was observed after surgical endometriosis resection. The receiver operating characteristic curve analysis determined the reference values for the serum lactoferrin and anti-lactoferrin antibody levels. Patients whose serum level exceeded the reference anti-lactoferrin antibody value were significantly higher in more than 40% of cases in the endometriosis group. The rate is comparable to that of autoimmune diseases. This is the first report that anti-lactoferrin antibody is frequently observed in patients with endometriosis, adding a new perspective to the understanding of the pathology of endometriosis although precisely elucidating the mechanism by which lactoferrin and anti-lactoferrin antibody appear in endometriosis in the future is necessary.

Neutrophil extracellular traps and pulmonary fibrosis: an update

Pulmonary fibrosis (PF) is a serious and often fatal illness that occurs in various clinical settings and represents a significant unmet medical need. Increasing evidence indicates that neutrophil extracellular traps (NETs) contribute significantly to the progression of PF. Therefore, understanding the pathways by which NETs contribute to the disease is crucial for developing effective treatments. This review focuses on the formation of NETs and the common mechanisms of NETs in PF.

Neutrophil inhibition improves acute inflammation in a murine model of viral myocarditis

AIMS

Viral myocarditis (VM) is an inflammatory pathology of the myocardium triggered by a viral infection that may cause sudden death or heart failure (HF), especially in the younger population. Current treatments only stabilize and improve cardiac function without resolving the underlying inflammatory cause. The factors that induce VM to progress to HF are still uncertain, but neutrophils have been increasingly associated with the negative evolution of cardiac pathologies. The present study investigates the contribution of neutrophils to VM disease progression in different ways.

METHODS AND RESULTS

In a coxsackievirus B3- (CVB3) induced mouse model of VM, neutrophils and neutrophil extracellular traps (NETs) were prominent in the acute phase of VM as revealed by enzyme-linked immunosorbent assay analysis and immunostaining. Anti-Ly6G-mediated neutrophil blockade starting at model induction decreased cardiac necrosis and leucocyte infiltration, preventing monocyte and Ly6CHigh pro-inflammatory macrophage recruitment. Furthermore, genetic peptidylarginine deiminase 4-dependent NET blockade reduced cardiac damage and leucocyte recruitment, significantly decreasing cardiac monocyte and macrophage presence. Depleting neutrophils with anti-Ly6G antibodies at 7 days post-infection, after the acute phase, did not decrease cardiac inflammation.

CONCLUSION

Collectively, these results indicate that the repression of neutrophils and the related NET response in the acute phase of VM improves the pathological phenotype by reducing cardiac inflammation.

The methylome and cell-free DNA: current applications in medicine and pediatric disease

DNA methylation is an epigenetic mechanism that contributes to cell regulation and development, and different methylation patterns allow for the identification of cell and tissue type. Cell-free DNA (cfDNA) is composed of small circulating fragments of DNA found in plasma and urine. Total cfDNA levels correlate with the presence of inflammation and tissue injury in a variety of disease states. Unfortunately, the utility of cfDNA is limited by its lack of tissue or cell-type specificity. However, methylome analysis of cfDNA allows the identification of the tissue or cell type from which cfDNA originated. Thus, methylation patterns in cfDNA from tissues isolated from direct study may provide windows into health and disease states, thereby serving as a "liquid biopsy". This review will discuss methylation and its role in establishing cellular identity, cfDNA as a biomarker and its pathophysiologic role in the inflammatory process, and the ways cfDNA and methylomics can be jointly applied in medicine. IMPACT: Cell-free DNA (cfDNA) is increasingly being used as a noninvasive diagnostic and disease-monitoring tool in pediatric medicine. However, the lack of specificity of cfDNA limits its utility. Identification of cell type-specific methylation signatures can help overcome the limited specificity of cfDNA. As knowledge of the cfDNA methylome improves, cfDNA will be more broadly applied in medicine, such that clinicians will need to understand the methods and applications of its use.