Neutrophil extracellular traps induce endothelial dysfunction in systemic lupus erythematosus through the activation of matrix metalloproteinase-2

Bacterial Brain Abscesses Expand Despite Effective Antibiotic Treatment: A Process Powered by Osmosis Due to Neutrophil Cell Death

BACKGROUND AND OBJECTIVES

A bacterial brain abscess is an emergency and should be drained of pus within 24 hours of diagnosis, as recently recommended. In this cross-sectional study, we investigated whether delaying pus drainage entails brain abscess expansion and what the underlying mechanism might be.

METHODS

Repeated brain MRI of 47 patients who did not undergo immediate pus drainage, pus osmolarity measurements, immunocytochemistry, proteomics, and 18F-fluorodeoxyglucose positron emission tomography.

RESULTS

Time from first to last MRI before neurosurgery was 1 to 14 days. Abscesses expanded in all but 2 patients: The median average increase was 23% per day (range 0%-176%). Abscesses expanded during antibiotic therapy and even if the pus did not contain viable bacteria. In a separate patient cohort, we found that brain abscess pus tended to be hyperosmolar (median value 360 mOsm; range 266-497; n = 14; normal cerebrospinal fluid osmolarity is ∼290 mOsm). Hyperosmolarity would draw water into the abscess cavity, causing abscess expansion in a ballooning manner through increased pressure in the abscess cavity. A mechanism likely underlying pus hyperosmolarity was the recruitment of neutrophils to the abscess cavity with ensuing neutrophil cell death and decomposition of neutrophil proteins and other macromolecules to osmolytes: Pus analysis showed the presence of neutrophil proteins (protein-arginine deiminases, citrullinated histone, myeloperoxidase, elastase, cathelicidin). Previous studies have shown very high levels of osmolytes (ammonia, amino acids) in brain abscess pus. 18F-fluorodeoxyglucose positron emission tomography showed focal neocortical hypometabolism 1 to 8 years after brain abscess, indicating long-lasting damage to brain tissue.

CONCLUSION

Brain abscesses expand despite effective antibiotic treatment. Furthermore, brain abscesses cause lasting damage to surrounding brain tissue. These findings support drainage of brain abscesses within 24 hours of diagnosis.

Elevated matrix metalloproteinase‑9 expression is associated with COVID‑19 severity: A meta‑analysis

The present meta-analysis investigated the clinical value of serum matrix metalloproteinase (MMP)-9 levels in Coronavirus Disease 2019 (COVID-19) patients. Studies assessing the outcomes of patients with COVID-19 in correlation with the MMP-9 levels were retrieved from PubMed, Web of Science, EMBASE, Cochrane, WANFANG, and CNKI. A meta-analysis was performed to compare the serum MMP-9 levels between different patient groups: Severe vs. non-severe; acute respiratory distress syndrome (ARDS) vs. non-ARDS; non-survivors vs. survivors; neurologic syndrome vs. non-neurologic syndrome; and obese diabetic vs. non-obese diabetic. A total of 2,062 COVID-19-confirmed patients from 12 studies were included in this meta-analysis. The serum MMP-9 levels were significantly higher in patients with severe COVID-19 than in those with non-severe COVID-19 [weighted mean difference (WMD) 246.61 (95% confidence interval (CI), 115.86-377.36), P<0.001]. Patients with ARDS exhibited significantly higher MMP-9 levels than those without ARDS [WMD 248.55 (95% CI, 63.84-433.25), P<0.001]. The MMP-9 levels in the non-survivors did not significantly differ from those in the survivors [WMD 37.79 (95% CI, -18.08-93.65), P=0.185]. Patients with comorbidities, including neurological syndromes, and obese diabetic patients had significantly higher MMP-9 levels than those without comorbidities [WMD 170.73 (95% CI, 95.61-245.85), P<0.001]. Serum MMP-9 levels were associated with COVID-19 severity and may serve as a therapeutic target for improving the prognosis of patients with COVID-19.

Recent advances in the role of neutrophils and neutrophil extracellular traps in acute pancreatitis

Pancreatitis is an inflammatory disease, which is triggered by adverse events in acinar cells of the pancreas. After the initial injury, infiltration of neutrophils in pancreas is observed. In the initial stages of pancreatitis, the inflammation is sterile. It has been shown that the presence of neutrophils at the injury site can modulate the disease. Their depletion in experimental animal models of the acute pancreatitis has been shown to be protective. But information on mechanism of contribution to inflammation by neutrophils at the injury site is not clear. Once at injury site, activated neutrophils release azurophilic granules containing proteolytic enzymes and generate hypochlorous acid which is a strong microbicidal agent. Additionally, emerging evidence shows that neutrophil extracellular traps (NETs) are formed which consist of decondensed DNA decorated with histones, proteases and granular and cytosolic proteins. NETs are considered mechanical traps for microbes, but there is preliminary evidence to indicate that NETs, which constitute a special mechanism of the neutrophil defence system, play an adverse role in pancreatitis by contributing to the pancreatic inflammation and distant organ injury. This review presents the overall current information about neutrophils and their role including NETs in acute pancreatitis (AP). It also highlights current gaps in knowledge which should be explored to fully elucidate the role of neutrophils in AP and for therapeutic gains.

Qualitative Proteome-wide Lysine Crotonylation Profiling Reveals Protein Modification Alteration in the Leukocyte Extravasation Pathway in Systemic Lupus Erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is a severe systemic autoimmune disease with multiple manifestations. Lysine crotonylation (Kcr) is a newly discovered posttranslational modification epigenetic pattern that may affect gene expression and is linked to diseases causally.

METHODS

We collected blood samples from 11 SLE individuals and 36 healthy subjects. Then, we used highly sensitive liquid chromatography-mass spectrometry technology to carry out proteomics and quantitative crotonylome analysis of SLE peripheral blood mononuclear cells in this investigation, which indicated the unique etiology of SLE. Finally, we verified the expression of critical protein in the leukocyte extravasation pathway by online database analysis and Western blot.

RESULTS

There were 618 differentially expressed proteins (DEPs), and 612 crotonylated lysine sites for 272 differentially modified proteins (DMPs) found. These DEPs and DMPs are primarily enriched in the leukocyte extravasation signaling pathway, such as MMP8, MMP9, and ITGAM.

CONCLUSIONS

This is the first study of crotonylated modification proteomics in SLE. The leukocyte extravasation signaling pathway had a considerable concentration of DEPs and DMPs, indicating that this pathway may be involved in the pathogenic development of SLE.

Neutrophil nucleus: shaping the past and the future

Neutrophils are innate immune cells that are key to protecting the host against infection and maintaining body homeostasis. However, if dysregulated, they can contribute to disease, such as in cancer or chronic autoinflammatory disorders. Recent studies have highlighted the heterogeneity in the neutrophil compartment and identified the presence of immature neutrophils and their precursors in these pathologies. Therefore, understanding neutrophil maturity and the mechanisms through which they contribute to disease is critical. Neutrophils were first characterized morphologically by Ehrlich in 1879 using microscopy, and since then, different technologies have been used to assess neutrophil maturity. The advances in the imaging field, including state-of-the-art microscopy and machine learning algorithms for image analysis, reinforce the use of neutrophil nuclear morphology as a fundamental marker of maturity, applicable for objective classification in clinical diagnostics. New emerging approaches, such as the capture of changes in chromatin topology, will provide mechanistic links between the nuclear shape, chromatin organization, and transcriptional regulation during neutrophil maturation.

The role of neutrophil extracellular traps in sepsis and sepsis-related acute lung injury

Neutrophils release neutrophil extracellular traps (NETs) to trap pathogenic microorganisms. NETs are involved in the inflammatory response and bacterial killing and clearance. However, their excessive activation can lead to an inflammatory storm in the body, which may damage tissues and cause organ dysfunction. Organ dysfunction is the main pathophysiological cause of sepsis and also a cause of the high mortality rate in sepsis. Acute lung injury caused by sepsis accounts for the highest proportion of organ damage in sepsis. NET formation can lead to the development of sepsis because by promoting the release of interleukin-1 beta, interleukin-8, and tumor necrosis factor-alpha, thereby accelerating acute lung injury. In this review, we describe the critical role of NETs in sepsis-associated acute lung injury and review the current knowledge and novel therapeutic approaches.

Light-induced circadian rhythm disorder leads to microvascular dysfunction via up-regulating NETs

Circadian rhythm is a physical, mental, and behavioral pattern over the course of 24-hour cycle, and its disturbance is associated with increased risk of cardiovascular diseases. Microvascular dysfunction serves as an important cause of cardiovascular disease, but the relationship between rhythm disturbances and microcirculation remains elusive. Herein, we constructed the mice model of circadian rhythm disturbance and investigated the alterations of microvascular conditions. It was revealed that coronary microcirculatory function and cardiac diastolic function were significantly reduced, along with endothelium-dependent diastolic function of microvessels remarkably impaired in the rhythm-disordered group of mice compared to the control group. Notably, rhythm disturbance led to a significant upregulation of neutrophil extracellular traps (NETs) levels in mice, which cause endothelial dysfunction by inhibiting microvascular endothelial cell activity and migration capacity as well as inducing apoptosis. Additionally, intraperitoneal injection of Cl-amidine suppressed the production of NETs, which further improved coronary microcirculatory function and endothelium-dependent diastolic function. In conclusion, this study demonstrated that circadian rhythm disorders could induce the development of coronary microvascular dysfunction (CMD) through the up-regulation of NETs, providing a potential therapeutic direction for the treatment of CMD.

Endothelial cell activation and glycocalyx shedding - potential as biomarkers in patients with lupus nephritis

Lupus nephritis (LN) is a common and severe manifestation of systemic lupus erythematosus and an important cause of acute and chronic kidney injury. Early diagnosis of LN and preventing relapses are key to preserving renal reserve. However, due to the complexity and heterogeneity of the disease, clinical management remains challenging. Kidney biopsy remains the gold standard for confirming the diagnosis of LN and subsequent assessment of kidney histopathology, but it is invasive and cannot be repeated frequently. Current clinical indicators of kidney function such as proteinuria and serum creatinine level are non-specific and do not accurately reflect histopathological changes, while anti-dsDNA antibody and C3 levels reflect immunological status but not kidney injury. Identification of novel and specific biomarkers for LN is prerequisite to improve management. Renal function deterioration is associated with changes in the endothelial glycocalyx, a delicate gel-like layer located at the interface between the endothelium and bloodstream. Inflammation induces endothelial cell activation and shedding of glycocalyx constituents into the circulation. This review discusses the potential role of soluble glycocalyx components as biomarkers of active LN, especially in patients in whom conventional serological and biochemical markers do not appear helpful.

Association between neutrophil/lymphocyte ratio and disease severity in scleroderma patients

Introduction

Systemic sclerosis is a chronic and progressive connective tissue disease with various manifestation. Inflammatory status is developed in early stages and is followed by major organs' dysfunction. Disease severity is evaluated mostly through Medsger scale. There is not any single laboratory test to evaluate disease severity, although some hematologic can reflect disease severity. In this study, we evaluated the association between hematologic indices (specially Neutrophil/Lymphocyte ratio) and Medsger score of disease severity.

Materials and methods

One hundred and twenty-three patients along with the same number of healthy controls were enrolled in this study. Demographic information and past medical records were gathered in first appointment. Hematologic indices were calculated based on the laboratory findings and the association between these indices and Medsger score of disease severity was evaluated.

Results

One hundred and twenty-three patients with mean disease duration of 9.54 and mean Medsger score of 7.42 were investigated in this study. Neutrophil count, erythrocyte sedimentation rate, red cell distribution width and NLR were significantly higher and mean platelets volume was significantly lower in SSc patients in comparison to controls. NLR was significantly correlated with pulmonary and cardiac involvements and Monocyte/Lymphocyte ratio was significantly correlated with the involvement of joint and tendons. We showed that NLR is a predictive factor for the severity of systemic sclerosis. We also found a cut off Value of 1.9 for NLR as a predictor for disease severity in our patients.

Conclusion

Our study shows that SSc and its severity is associated with some hematologic indices like NLR, MLR, platelets and hemoglobin. These indices can also specifically predict the involvement of some organs.

The intricate relationship between autoimmunity disease and neutrophils death patterns: a love-hate story

Autoimmune diseases are pathological conditions that result from the misidentification of self-antigens in immune system, leading to host tissue damage and destruction. These diseases can affect different organs and systems, including the blood, joints, skin, and muscles. Despite the significant progress made in comprehending the underlying pathogenesis, the complete mechanism of autoimmune disease is still not entirely understood. In autoimmune diseases, the innate immunocytes are not functioning properly: they are either abnormally activated or physically disabled. As a vital member of innate immunocyte, neutrophils and their modes of death are influenced by the microenvironment of different autoimmune diseases due to their short lifespan and diverse death modes. Related to neutrophil death pathways, apoptosis is the most frequent cell death form of neutrophil non-lytic morphology, delayed or aberrant apoptosis may contribute to the development anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV). In addition, NETosis, necroptosis and pyroptosis which are parts of lytic morphology exacerbate disease progression through various mechanisms in autoimmune diseases. This review aims to summarize recent advancements in understanding neutrophil death modes in various autoimmune diseases and provide insights into the development of novel therapeutic approaches for autoimmune diseases.

NETosis: an emerging therapeutic target in renal diseases

Introduction

Neutrophil extracellular traps (NETs) are web-like structures composed of nuclear and granular components. The primary role of NETS is to prevent the dissemination of microbes and facilitate their elimination. However, this process is accompanied by collateral proinflammatory adverse effects when the NET release becomes uncontrollable, or clearance is impaired. Although NET-induced organ damage is conducted primarily and indirectly via immune complexes and the subsequent release of cytokines, their direct effects on cells are also remarkable. NETosis plays a critical pathogenic role in several renal disorders, such as the early phase of acute tubular necrosis, anti-neutrophil cytoplasmic antibody-mediated renal vasculitis, lupus nephritis, thrombotic microangiopathies, anti-glomerular basement membrane disease, and diabetic nephropathy. Their substantial contribution in the course of these disorders makes them a desirable target in the therapeutic armamentarium. This article gives an in-depth review of the heterogeneous pathogenesis and physiological regulations of NETosis and its pivotal role in renal diseases. Based on the pathogenesis, the article also outlines the current therapeutic options and possible molecular targets in the treatment of NET-related renal disorders.

Methods

We carried out thorough literature research published in PubMed and Google Scholar, including a comprehensive review and analysis of the classification, pathomechanisms, and a broad spectrum of NET-related kidney disorders.

Conclusions

NETosis plays a pivotal role in certain renal diseases. It initiates and maintains inflammatory and autoimmune disorders, thus making it a desirable target for improving patient and renal outcomes. Better understanding and clinical translation of the pathogenesis are crucial aspects to treatment, for improving patient, and renal outcomes.

MMP-2 and its implications on cardiac function and structure: Interplay with inflammation in hypertension

Hypertension is one of the leading risk factors for the development of heart failure. Despite being a multifactorial disease, in recent years, preclinical and clinical studies suggest strong evidence of the pivotal role of inflammatory cells and cytokines in the remodeling process and cardiac dysfunction. During the heart remodeling, activation of extracellular matrix metalloproteinases (MMPs) occurs, with MMP-2 being one of the main proteases secreted by cardiomyocytes, fibroblasts, endothelial and inflammatory cells in cardiac tissue. In this review, we will address the process of cardiac remodeling and injury induced by the increase in MMP-2 and the main signaling pathways involving cytokines and inflammatory cells in the process of transcriptional, secretion and activation of MMP-2. In addition, an interaction and coordinated action between MMP-2 and inflammation are explored and significant in maintaining the cardiac cycle. These observations suggest that new therapeutic opportunities targeting MMP-2 could be used to reduce inflammatory biomarkers and reduce cardiac damage in hypertension.

The Role of Neutrophil Extracellular Traps (NETs) in the Pathogenesis of Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease of unknown aetiology [...].

Neutrophil extracellular traps mediate deep vein thrombosis: from mechanism to therapy

Deep venous thrombosis (DVT) is a part of venous thromboembolism (VTE) that clinically manifests as swelling and pain in the lower limbs. The most serious clinical complication of DVT is pulmonary embolism (PE), which has a high mortality rate. To date, its underlying mechanisms are not fully understood, and patients usually present with clinical symptoms only after the formation of the thrombus. Thus, it is essential to understand the underlying mechanisms of deep vein thrombosis for an early diagnosis and treatment of DVT. In recent years, many studies have concluded that Neutrophil Extracellular Traps (NETs) are closely associated with DVT. These are released by neutrophils and, in addition to trapping pathogens, can mediate the formation of deep vein thrombi, thereby blocking blood vessels and leading to the development of disease. Therefore, this paper describes the occurrence and development of NETs and discusses the mechanism of action of NETs on deep vein thrombosis. It aims to provide a direction for improved diagnosis and treatment of deep vein thrombosis in the near future.

SARS-CoV-2 Spike Proteins and Cell-Cell Communication Induce P-Selectin and Markers of Endothelial Injury, NETosis, and Inflammation in Human Lung Microvascular Endothelial Cells and Neutrophils: Implications for the Pathogenesis of COVID-19 Coagulopathy

COVID-19 progression often involves severe lung injury, inflammation, coagulopathy, and leukocyte infiltration into pulmonary tissues. The pathogenesis of these complications is unknown. Because vascular endothelium and neutrophils express angiotensin-converting enzyme-2 and spike (S)-proteins, which are present in bodily fluids and tissues of SARS-CoV-2-infected patients, we investigated the effect of S-proteins and cell-cell communication on human lung microvascular endothelial cells and neutrophils expression of P-selectin, markers of coagulopathy, NETosis, and inflammation. Exposure of endothelial cells or neutrophils to S-proteins and endothelial-neutrophils co-culture induced P-selectin transcription and expression, significantly increased expression/secretion of IL-6, von Willebrand factor (vWF, pro-coagulant), and citrullinated histone H3 (cit-H3, NETosis marker). Compared to the SARS-CoV-2 Wuhan variant, Delta variant S-proteins induced 1.4-15-fold higher P-selectin and higher IL-6 and vWF. Recombinant tissue factor pathway inhibitor (rTFPI), 5,5'-dithio-bis-(2-nitrobenzoic acid) (thiol blocker), and thrombomodulin (anticoagulant) blocked S-protein-induced vWF, IL-6, and cit-H3. This suggests that following SARS-CoV-2 contact with the pulmonary endothelium or neutrophils and endothelial-neutrophil interactions, S-proteins increase adhesion molecules, induce endothelial injury, inflammation, NETosis and coagulopathy via the tissue factor pathway, mechanisms involving functional thiol groups, and/or the fibrinolysis system. Using rTFPI, effectors of the fibrinolysis system and/or thiol-based drugs could be viable therapeutic strategies against SARS-CoV-2-induced endothelial injury, inflammation, NETosis, and coagulopathy.

Effective Attenuation of Arteriosclerosis Following Lymphatic-Targeted Delivery of Hyaluronic Acid-Decorated Rapamycin Liposomes

Background

The activation of lymphatic vessel function is the crux to resolving atherosclerosis (AS), a chronic inflammatory disease. Rapamycin (RAPA) recently has attracted considerable attention as a potent drug to induce atherosclerotic plaque attenuation. The objective of this work was to develop a ligand-decorated, RAPA-loaded liposome for lymphatic-targeted delivery of drugs to improve abnormal lymphatic structure and function, resulting in highly effective regression of atherosclerotic plaques.

Methods

Hyaluronic acid-decorated, RAPA-loaded liposomes (HA-RL) were fabricated by emulsion-solvent evaporation. The average size, zeta potential, entrapment efficiency were characterized, and the stability and drug release in vitro were investigated. Furthermore, the in vitro and in vivo lymphatic targeting ability were evaluated on lymphatic endothelial cells and LDLR-/- mice, and the efficiency of this nano-system in inducing the attenuation of atherosclerotic plaques was confirmed.

Results

HA-RL had a size of 100 nm, over 90% drug encapsulation efficiency, the storage stability was distinguished, demonstrating a slow release from the lipid nano-carriers. The mean retention time (MRT) and elimination half-life (t1/2β) achieved from HA-RL were 100.27±73.08 h and 70.74±50.80 h, respectively. HA-RL acquired the most prominent efficacy of lymphatic-targeted delivery and atherosclerotic plaques attenuation, implying the successful implementation of this novel drug delivery system in vivo.

Conclusion

HA-RL exhibited the most appreciable lymphatic targeting ability and best atherosclerotic plaques attenuation efficiency, opening a new paradigm and promising perspective for the treatment of arteriosclerosis.

The Effect of Local Anesthetics on Neutrophils in the Context of Different Isolation Techniques

Various functions of polymorphonuclear neutrophils (PMNs) are related to diseases and postoperative plasma changes. The influence of some local anesthetics (LAs) on PMNs obtained by conventional isolation methods and their functions has already been demonstrated. This study investigates the effect of selected LAs on PMNs, comparing a new isolation method with conventional ones. To obtain the PMNs, we performed either gelafundin sedimentation, hypotonic lysis or density gradient centrifugation. Subsequently, PMNs were mixed with different concentrations of bupivacaine, levobupivacaine, lidocaine or ropivacaine. Live cell imaging and flow cytometry were performed to quantify the migration, ROS production, NETosis and antigen expression of PMNs. We found the inhibition of chemotaxis and ROS production by LAs. PMNs showed a strong reduction in time to half maximal NETosis in response to bupivacaine and lidocaine, but not to levobupivacaine and ropivacaine. We also found distinct differences in survival time and migration duration between the isolation methods. This suggests that the careful selection of LAs has a short-term impact on in vitro PMNs.

The central role of neutrophil extracellular traps (NETs) and by-products in COVID-19 related pulmonary thrombosis

Extracellular trap networks (neutrophil extracellular traps [NETs]) of polymorphonuclear neutrophils are mesh-like substances that prevent the spread of pathogens. They primarily consist of DNA skeletons, histones, granule components, and cytoplasmic proteins. NETs formation requires a certain environment and there are different pathways for NETs production. However, it is still not clear how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) promotes NETs. NETs exert antiinflammatory effects through immune response, while they can also lead to certain adverse outcomes, such as the development of immunothrombosis. Coronavirus disease 2019 (COVID-19) is an inflammatory reaction affecting various organs caused by SARS-CoV-2, especially the lungs. NETs production and disease severity are linked with unique neutrophil clusters by single-cell RNA sequencing. NETs might exert an anti-inflammatory role in the initial stage of lung tissue inflammation. Nevertheless, numerous studies and cases have shown that they can also result in pulmonary thrombosis. There is mounting evidence that NETs are tightly related with COVID-19 pulmonary thrombosis, and many studies on the mechanisms are involved. The role and mechanism of NETs in the development of pulmonary thrombosis will be the main topics of this manuscript. Additionally, we address the potential targeting of NETs in COVID-19 patients.

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.

Neutrophil extracellular traps (NET): not only antimicrobial but also modulators of innate and adaptive immunities in inflammatory autoimmune diseases

Polymorphonuclear neutrophils (PMN) represent one of the first lines of defence against invading pathogens and are the most abundant leucocytes in the circulation. Generally described as pro-inflammatory cells, recent data suggest that PMN also have immunomodulatory capacities. In response to certain stimuli, activated PMN expel neutrophil extracellular traps (NET), structures made of DNA and associated proteins. Although originally described as an innate immune mechanism fighting bacterial infection, NET formation (or probably rather an excess of NET together with impaired clearance of NET) may be deleterious. Indeed, NET have been implicated in the development of several inflammatory and autoimmune diseases as rheumatoid arthritis or systemic lupus erythematosus, as well as fibrosis or cancer. They have been suggested as a source of (neo)autoantigens or regulatory proteins like proteases or to act as a physical barrier. Different mechanisms of NET formation have been described, leading to PMN death or not, depending on the stimulus. Interestingly, NET may be both pro-inflammatory and anti-inflammatory and this probably partly depends on the mechanism, and thus the stimuli, triggering NET formation. Within this review, we will describe the pro-inflammatory and anti-inflammatory activities of NET and especially how NET may modulate immune responses.

Differential expression of IFN-α, IL-12 and BAFF on renal immune cells and its relevance to disease activity and treatment responsiveness in patients with proliferative lupus nephritis

OBJECTIVE

Since molecularly targeted therapies are emerging for treating lupus nephritis (LN), this study aimed to assess the immunohistochemical findings of the cytokines in renal tissue and their pathological and clinical relevance in LN.

METHODS

Fifty patients with proliferative LN formed the case group; 5 with LN class II, IgA nephropathy and 10 with idiopathic haematuria were enrolled as controls. Immunohistochemical analysis for CD3, CD20, interferon (IFN)-α, interleukin (IL)-12/p40 and B-cell activating factor (BAFF) was performed by scoring the number of positive cells/area of the cortex. All immunohistochemical investigations were performed on formalin-fixed paraffin-embedded renal tissue. Proliferative LN cases were grouped by the dominant expression of IFN-α, IL-12/p40 and BAFF, and subsequently, clinicopathological features were compared.

RESULTS

Clinical data of patients with proliferative LN included urine protein creatinine ratio, 2.2 g/gCre; anti-double-stranded DNA antibody, 200.9 IU/mL; total complement activity (CH50), 21.9 U/mL and SLE Disease Activity Index, 19.8 points. Proliferative LN cases, including class III (n=18) and IV (n=32), were classified into three subgroups according to the immunohistochemical score based on the dominancy of IFN-α (n=17), IL-12 (n=16) and BAFF group (n=17) proteins. Hypocomplementaemia and glomerular endocapillary hypercellularity were significantly increased in the IFN-α group, whereas chronic lesions were significantly higher in the IL-12 group (p<0.05). The IFN-α group had a poorer renal prognosis in treatment response after 52 weeks.

CONCLUSIONS

The immunohistochemistry (IHC) of IFN-α, IL-12 and BAFF for proliferative LN enabled grouping. Especially, the IFN-α and IL-12 groups showed different clinicopathological features and renal prognoses. The results indicated the possibility of stratifying cases according to the IHC of target molecules, which might lead to precision medicine.

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.

Connective Tissue Disease Associated Interstitial Lung Disease

Connective tissue disease associated interstitial lung disease (CTD-ILD) is a heterogenous collection of conditions with a diverse spectrum of interstitial lung disease (ILD) manifestations. Currently, clinical practice of lung-directed immunosuppression in CTD-ILD is supported by several randomized, placebo-controlled trials (RCTs) in patients with scleroderma and several observational, retrospective studies in other autoimmune conditions. However, given the harm of immunosuppression in idiopathic pulmonary fibrosis, there is an urgent need for RCTs of immunosuppression and antifibrotic agents in fibrotic CTD-ILD populations as well as the study of intervention in patients with subclinical CTD-ILD.

Neutrophil diversity in inflammation and cancer

Neutrophils are the most abundant circulating leukocytes in humans and the first immune cells recruited at the site of inflammation. Classically perceived as short-lived effector cells with limited plasticity and diversity, neutrophils are now recognized as highly heterogenous immune cells, which can adapt to various environmental cues. In addition to playing a central role in the host defence, neutrophils are involved in pathological contexts such as inflammatory diseases and cancer. The prevalence of neutrophils in these conditions is usually associated with detrimental inflammatory responses and poor clinical outcomes. However, a beneficial role for neutrophils is emerging in several pathological contexts, including in cancer. Here we will review the current knowledge of neutrophil biology and heterogeneity in steady state and during inflammation, with a focus on the opposing roles of neutrophils in different pathological contexts.

Crosstalk between oxidative stress and neutrophil response in early ischemic stroke: a comprehensive transcriptome analysis

Background

Ischemic stroke (IS) is the second leading cause of mortality worldwide, continuing to be a serious health concern. It is well known that oxidative stress and neutrophil response play vital roles in the pathophysiology of early IS. However, the complex interactions and critical genes associated with them have not been fully understood.

Methods

Two datasets (GSE37587 and GSE16561) from the Gene Expression Omnibus database were extracted and integrated as the discovery dataset. Subsequent GSVA and WGCNA approaches were used to investigate IS-specific oxidative stress-related genes (ISOSGS). Then, we explored IS-specific neutrophil-associated genes (ISNGS) using CIBERSORT analysis. Next, the protein-protein interaction network was established to ascertain candidate critical genes related with oxidative stress and neutrophil response. Furthermore, these candidate genes were validated using GSE58294 dataset and our clinical samples by RT-qPCR method. Finally, functional annotation, diagnostic capability evaluation and drug-gene interactions were performed by using GSEA analysis, ROC curves and DGIDB database.

Result

In our analysis of discovery dataset, 155 genes were determined as ISOSGS and 559 genes were defined as ISNGS. Afterward, 9 candidate genes were identified through the intersection of ISOSGS and ISNGS, PPI network construction, and filtration by degree algorithm. Then, six real critical genes, including STAT3, MMP9, AQP9, SELL, FPR1, and IRAK3, passed the validation using the GSE58294 dataset and our clinical samples. Further functional annotation analysis indicated these critical genes were associated with neutrophil response, especially neutrophil extracellular trap. Meanwhile, they had a good diagnostic performance. Lastly, 53 potential drugs targeting these genes were predicted by DGIDB database.

Conclusion

We identified 6 critical genes, STAT3, FPR1, AQP9, SELL, MMP9 and IRAK3, related to oxidative stress and neutrophil response in early IS, which may provide new insights into understanding the pathophysiological mechanism of IS. We hope our analysis could help develop novel diagnostic biomarkers and therapeutic strategies for IS.

Calciphylaxis and its co-occurrence with connective tissue diseases

Calciphylaxis, also known as calcific uremic arteriopathy, is a rare calcification syndrome that presents as ischemic skin necrosis and severe pain. It has a high mortality rate and is characterised by calcification of the small and medium arteries and micro-thrombosis. Calciphylaxis mainly occurs in patients with end-stage renal disease. In recent years, there have been an increasing number of cases of calciphylaxis associated with connective tissue diseases. Given the absence of clear diagnostic criteria for calciphylaxis thus far, an early diagnosis is crucial for designing an effective multidisciplinary treatment plan. In this article, we review the research progress on calciphylaxis and describe its characteristics in the context of connective tissue diseases.

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.

Insights into the pathogenic role of neutrophils in systemic lupus erythematosus

PURPOSE OF REVIEW

Although dysregulated adaptive immune response has been considered as the main culprit for systemic lupus erythematosus (SLE), emerging studies have indicated that innate immunity, functioning upstream of adaptive immunity, acts as an important trigger of autoimmune diseases and promotes SLE development. Here, we have reviewed the most recent findings to highlight the influence of neutrophils on SLE pathogenesis.

RECENT FINDINGS

Neutrophils participate in SLE development mainly via promoting self-antigen exposure and autoantibody production, advocating the release of type I interferons (IFNs) and other pro-inflammatory cytokines, and mediating systemic tissue injury. A recent study revealed that neutrophil ferroptosis exerts a strong pathogenic effect in SLE, and that dysregulated innate immunity is adequate to disrupt the homeostasis of immune tolerance.

SUMMARY

Insights into the pathogenic role of neutrophils in SLE will contribute to a more comprehensive understanding of this disease and may propose novel clinical targets for accurate diagnosis and precision medicine.

Neutrophil extracellular trap: A key player in the pathogenesis of autoimmune diseases

Numerous studies suggest that neutrophils might have a crucial role in the pathogenesis of systemic autoimmune diseases through neutrophil extracellular trap (NET) formation, production of pro-inflammatory cytokines, and organ destruction. NET components that are released into extracellular spaces can be considered autoantigens, which contribute to causing a break in self-tolerance. Subsequently, this leads to the development of autoimmune responses in predisposed individuals. Additionally, an imbalance between NET formation and NET degradation may prolong immune system contact with these modified autoantigens and enhance NET-induced tissue damage. In this review, we discuss the generation and clearance of the NET, as well as the role of NETosis in the pathogenesis of autoimmune disorders, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV), multiple sclerosis (MS), psoriasis, antiphospholipid syndrome (APS), and Type-1 diabetes mellitus (T1DM).

Low-density granulocytes in systemic autoimmunity and autoinflammation

A body of evidence has re-energized the interest on the role neutrophils in inflammatory and autoimmune conditions. For decades, neutrophils have been considered a homogenous population. Nevertheless, accumulating evidence suggests that neutrophils are more versatile and heterogeneous than initially considered. The notion of neutrophil heterogeneity has been supported by the identification of low-density granulocytes (LDGs) in systemic lupus erythematosus (SLE) and other systemic autoimmune and autoinflammatory conditions. Transcriptomic, epigenetic, proteomic, and functional analyses support that LDGs are a distinct subset of proinflammatory neutrophils implicated in the pathogenesis of SLE and other autoimmune diseases. Importantly, it remains incompletely characterized whether LDGs detected in other inflammatory/autoimmune conditions display the same phenotype that those present in SLE. A shared feature of LDGs across diseases is their association with vascular damage, an important contributor to morbidity and mortality in chronic inflammatory conditions. Additionally, the lack of specific markers to identify LDGs in circulation or in tissue, makes it a challenge to elucidate their role in the pathogenesis of inflammatory and autoimmune conditions. In this review, we aim to examine the evidence on the biology and the putative pathogenic role of LDGs in systemic autoimmune diseases.

Blood Neutrophil Count and Neutrophil-to-Lymphocyte Ratio for Prediction of Disease Progression and Mortality in Two Independent Systemic Sclerosis Cohorts

OBJECTIVE

To assess the predictive significance of blood neutrophil count and the ratio between neutrophil and lymphocyte count (neutrophil-to-lymphocyte ratio [NLR]) for disease severity and mortality in systemic sclerosis (SSc).

METHODS

Neutrophil and lymphocyte counts were prospectively measured in the Genetics versus Environment in Scleroderma Outcome Study (GENISOS) and the Scleroderma Lung Study II (SLS II). Forced vital capacity percent predicted (FVC%) and modified Rodnan skin thickness score (MRSS) were used as surrogate measures for disease severity. Longitudinal analyses were performed using generalized linear mixed models. Cox proportional hazards models evaluated the predictive significance of these cell counts for mortality.

RESULTS

Of the 447 SSc patients in the GENISOS cohort at the time of analysis, 377 (84.3%) had available baseline blood neutrophil and lymphocyte counts. Higher baseline neutrophil count and NLR predicted lower serially obtained FVC% (b = -4.74, P = 0.009 and b = -2.68, P = 0.028, respectively) and higher serially obtained MRSS (b = 4.07, P < 0.001 and b = 2.32, P < 0.001, respectively). Longitudinal neutrophil and NLR measurements also significantly correlated with lower concurrently obtained FVC% measurements and higher concurrently obtained MRSS. Baseline neutrophil count and NLR predicted increased risk of long-term mortality, even after adjustment for baseline demographic and clinical factors (hazard ratio [HR] 1.42, P = 0.02 and HR 1.48, P < 0.001, respectively). The predictive significance of higher baseline neutrophil count and NLR for declining FVC% and increased long-term mortality was confirmed in the SLS II.

CONCLUSION

Higher blood neutrophil count and NLR are predictive of more severe disease course and increased mortality, indicating that these easily obtainable laboratory studies might be a reflection of pathologic immune processes in SSc.

Neutrophil extracellular traps in central nervous system pathologies: A mini review

Neutrophils are the first cells to be recruited to sites of acute inflammation and contribute to host defense through phagocytosis, degranulation and neutrophil extracellular traps (NETs). Neutrophils are rarely found in the brain because of the highly selective blood-brain barrier (BBB). However, several diseases disrupt the BBB and cause neuroinflammation. In this regard, neutrophils and NETs have been visualized in the brain after various insults, including traumatic (traumatic brain injury and spinal cord injury), infectious (bacterial meningitis), vascular (ischemic stroke), autoimmune (systemic lupus erythematosus), neurodegenerative (multiple sclerosis and Alzheimer's disease), and neoplastic (glioma) causes. Significantly, preventing neutrophil trafficking into the central nervous system or NET production in these diseases alleviates brain pathology and improves neurocognitive outcomes. This review summarizes the major studies on the contribution of NETs to central nervous system (CNS) disorders.

Coagulation Disorders in Sepsis and COVID-19-Two Sides of the Same Coin? A Review of Inflammation-Coagulation Crosstalk in Bacterial Sepsis and COVID-19

Sepsis is a major cause of morbidity and mortality worldwide. Sepsis-associated coagulation disorders are involved in the pathogenesis of multiorgan failure and lead to a subsequently worsening prognosis. Alongside the global impact of the COVID-19 pandemic, a great number of research papers have focused on SARS-CoV-2 pathogenesis and treatment. Significant progress has been made in this regard and coagulation disturbances were once again found to underlie some of the most serious adverse outcomes of SARS-CoV-2 infection, such as acute lung injury and multiorgan dysfunction. In the attempt of untangling the mechanisms behind COVID-19-associated coagulopathy (CAC), a series of similarities with sepsis-induced coagulopathy (SIC) became apparent. Whether they are, in fact, the same disease has not been established yet. The clinical picture of CAC shows the unique feature of an initial phase of intravascular coagulation confined to the respiratory system. Only later on, patients can develop a clinically significant form of systemic coagulopathy, possibly with a consumptive pattern, but, unlike SIC, it is not a key feature. Deepening our understanding of CAC pathogenesis has to remain a major goal for the research community, in order to design and validate accurate definitions and classification criteria.

Beta 2 glycoprotein I and neutrophil extracellular traps: Potential bridge between innate and adaptive immunity in anti-phospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by recurrent vascular thrombosis and miscarriages in the absence of known causes. Antibodies against phospholipid-binding proteins (aPL) are pathogenic players in both clotting and pregnancy APS manifestations. There is sound evidence that antibodies specific for beta2 glycoprotein I (β2GPI) trigger thrombotic and pregnancy complications by interacting with the molecule on the membranes of different cell types of the coagulation cascade, and in placenta tissues. In addition to the humoral response against β2GPI, both peripheral and tissue CD4⁺ β2GPI-specific T cells have been reported in primary APS as well as in systemic lupus erythematosus (SLE)-associated APS. While adaptive immunity plays a clear role in APS, it is still debated whether innate immunity is involved as well. Acute systemic inflammation does not seem to be present in the syndrome, however, there is sound evidence that complement activation is crucial in animal models and can be found also in patients. Furthermore, neutrophil extracellular traps (NETs) have been documented in arterial and venous thrombi with different etiology, including clots in APS models. Keeping in mind that β2GPI is a pleiotropic glycoprotein, acting as scavenger molecule for infectious agents and apoptotic/damaged body constituents and that self-molecules externalized through NETs formation may become immunogenic autoantigens, we demonstrated β2GPI on NETs, and its ability to stimulate CD4⁺β2GPI-specific T cells. The aim of this review is to elucidate the role of β2GPI in the cross-talk between the innate and adaptive immunity in APS.

Necrostatin-1 Alleviates Diffuse Pulmonary Haemorrhage by Preventing the Release of NETs via Inhibiting NE/GSDMD Activation in Murine Lupus

Diffuse alveolar haemorrhage (DAH) is a rapidly developing condition owing to a lack of effective treatment and resulting in a high mortality rate in systemic lupus erythematosus (SLE). Neutrophil extracellular traps (NETs) contain numerous antigens and proinflammatory substances that directly damage the vascular endothelium and aggravate vascular inflammation, which is considered an important pathogenic factor of DAH in SLE. Therefore, blocking the release of NETs from neutrophils is an important target for the treatment of DAH in SLE. In this study, we investigated whether the inhibition of neutrophils releasing NETs could relieve DAH in SLE. Necrostatin-1 (Nec-1), a small molecule, has been reported to inhibit the release of NETs by neutrophils. In vitro experiments revealed that Nec-1 inhibited alveolar epithelial cell damage by preventing the release of NETs. Furthermore, vivo studies showed that Nec-1 alleviated lupus pulmonary haemorrhage in mice by reducing lung pathology severity, body weight, and serum inflammatory cytokine levels. Mechanistically, Nec-1 prevented NET release by inhibiting neutrophil elastase (NE) activation and N-Gasdermin D (N-GSDMD) expression. Additionally, immunohistochemistry and immunofluorescence findings showed that Nec-1 decreased NE expression in the lung tissues of mice with lupus pulmonary haemorrhage. Thus, NETs released by neutrophils contributed to the pathogenesis of DAH in SLE, and Nec-1 showed protective effects by the inhibition of NET production via the reduction of NE activation and N-GSDMD expression.

Neutralizing Anti‒DNase 1 and ‒DNase 1L3 Antibodies Impair Neutrophil Extracellular Traps Degradation in Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a debilitating inflammatory skin disorder characterized by abscess-like nodules and boils resulting in fistulas and tissue scarring. We previously reported evidence of an autoimmune signature in HS, characterized by enhanced neutrophil extracellular trap (NET) infiltration in HS skin lesions and dysregulation of the adaptive immune system characterized by the presence of autoantibodies. Timely removal of NETs is critical for tissue homeostasis to prevent a dysregulated generation of modified autoantigens and tissue damage. DNases 1 and 1L3 play important roles in proper NET removal. We tested the hypothesis that NETs in patients with HS are not effectively cleared owing to the presence of antibodies against DNase 1 and DNase 1L3. We report that HS serum poorly degraded NETs. Addition of exogenous DNase 1 restored NET degradation capabilities in a subset of HS samples. DNase 1 activity was significantly decreased in HS sera. Anti‒DNase 1 and ‒DNase 1L3 antibodies were detected in serum samples and skin lesions from patients with HS. Purified IgGs from HS decreased DNase 1 activity and NET degradation. Taken together, this identification of neutralizing antibodies against nucleases in HS expands the understanding of the pathogenesis of this disease to support an autoimmune mechanism in its underlying pathogenesis.

Neutrophil extracellular traps in autoimmune diseases: Analysis of the knowledge map

Introduction

Recent studies have shown much progress in the research of exosomes in AIDs. However, there is no bibliometric analysis in this research field. This study aimed to provide a bibliometrics review of the knowledge structure and research hotspots of neutrophil extracellular traps (NETs) in autoimmune diseases (AIDs).

Methods

Articles relevant to NETs in AIDs from 2010 to 2022 were retrieved through the Web of Science Core Collection (WoSCC) database. This bibliometric analysis was performed by VOSview, CiteSpace, and Scimago Graphica.

Results

A total of 289 papers analyzed in this research were from 493 organizations in 47 countries by 1537 authors. They were published in 133 journals and cited 20,180 citations from 2,465 journals. The number of annual publications in this field is growing steadily and rapidly, with the United States, China and Germany leading the research effort. Frontiers in Immunology and Journal of Immunology have significantly impacted research in this field. Kaplan, Mariana J, from the National Institutes of Health (The United States), has the most published articles, and Brinkmann, v, from Max Planck Institute for Infection Biology (Germany), is the most co-cited author. Systemic lupus erythematosus and rheumatoid arthritis are the leading topics in this field. The trend of clinical application in the future is the development of new therapies by controlling NETs in the progression of AIDs.

Conclusions

Our study summarized the research trends and developments of NETs in AIDs in recent years and would provide a reference for scholars in this field.

A Well-Intentioned Enemy in Autoimmune and Autoinflammatory Diseases: NETosis

Neutrophils are an essential member of the innate immune system derived from the myeloid stem cell series and develop in the bone marrow. The action of neutrophils defined in immune response includes phagocytosis, degranulation, cytokine production, and neutrophil extracellular traps. The success of the host immune defense depends on effective neutrophil activation. Recent studies have shown that neutrophils that have completed their task in the field of inflammation rejoin circulation. Uncontrolled inflammatory response and dysregulated immune responses to the host are important factors in the development of acute and chronic diseases. Neutrophils are the first cells to be drawn into the field at the time of inflammation. They have developed response strategies that produce proinflammatory cytokines and are known as neutrophil extracellular traps since they create mesh-like structures with their DNA contents into the external environment and release their granular proteins in this way. This article summarizes numerous recent studies and reviews the role of neutrophil extracellular traps in autoimmune and autoinflammatory diseases in the hope, that this will lead to the development of more effective treatments. In addition, in this review, the role of neutrophil extracellular trap formation in some pediatric autoimmune diseases is emphasized.

Neutrophil Extracellular Traps Induce Glomerular Endothelial Cell Dysfunction and Pyroptosis in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease. Neutrophil extracellular traps (NETs) are a network structure composed of loose chromatin and embedded with multiple proteins. Here, we observed increased NETs deposition in the glomeruli of DKD patients and diabetic mice (streptozotocin-induced or db/db mice). After NETs were degraded with DNase I, diabetic mice exhibited attenuated glomerulopathy and glomerular endothelial cells (GECs) injury. We also observed alleviated glomerulopathy and GECs injury in peptidylarginine deiminase 4-knockout mice with streptozotocin-induced diabetes. In vitro, NETs-induced GECs pyroptosis was characterized by pore formation in the cell membrane, dysregulation of multiple genes involved in cell membrane function, and increased expression of pyroptosis-related proteins. Strengthening the GECs surface charge by oleylamine significantly inhibited NETs-induced GECs pyroptosis. These findings suggest that the GECs charge-related pyroptosis is involved in DKD progression, which is promoted by NETs.

Recent Insights into Neutrophil Extracellular Traps in Cardiovascular Diseases

Neutrophils are primary effector cells of the innate immune system. Emerging evidence has consistently shown that activated neutrophils produce and release neutrophil extracellular traps (NETs) that play roles in immunity and non-infectious diseases. NETs are composed of DNA and proteins and serve as a structural platform for pathogen sequestration and degradation. In contrast to their protective role during pathogenic infection, NETs are pathologically involved in cardiovascular disease (CVD). In this review, we introduce the formation, release, and clearance of NETs and the regulatory mechanisms of NETs formation, followed by an overview of the clinical evidence for the involvement of NETs in CVD. Because atherosclerosis is a fundamental part of the pathogenesis of CVD, we chose to focus on the mechanisms by which NETs promote endothelial cell damage and collaborate with macrophages and platelets to accelerate plaque progression and thrombosis. Finally, we present options for clinical intervention to inhibit NETs production and release in the treatment of CVD. In conclusion, this review integrates the latest findings and provides new insights into NETs, which represent a novel biomarker and therapeutic target in clinical practice.

Immune mechanisms associated with cardiovascular disease in systemic lupus erythematosus: A path to potential biomarkers

Systemic lupus erythematosus (SLE) patients display an increased risk of cardiovascular disease (CVD). With the improved clinical management of other classical severe manifestation of the disease, CVD is becoming one of the most relevant complications of SLE, and it is an important factor causing morbidity and mortality. Several immune constituents have been shown to be involved in the pathogenesis of atherosclerosis and endothelial damage in SLE patients, including specific circulating cell populations, autoantibodies, and inflammatory mediators. In this review, we summarize the presentation of CVD in SLE and the role of the autoimmune responses present in SLE patients in the induction of atherogenesis, endothelial impairment and cardiac disease. Additionally, we discuss the utility of these immune mediators as early CVD biomarkers and targets for clinical intervention in SLE patients.

Neutrophils' Extracellular Trap Mechanisms: From Physiology to Pathology

Neutrophils are an essential part of the innate immune system and the first line of defense against invading pathogens. They phagocytose, release granular contents, produce reactive oxygen species, and form neutrophil extracellular traps (NETs) to fight pathogens. With the characterization of NETs and their components, neutrophils were identified as players of the innate adaptive crosstalk. This has placed NETs at the center not only of physiological but also pathological processes. Aside from their role in pathogen uptake and clearance, NETs have been demonstrated to contribute to the resolution of inflammation by forming aggregated NETs able to degrade inflammatory mediators. On the other hand, NETs have the potential to foster severe pathological conditions. When homeostasis is disrupted, they occlude vessels and ducts, serve as sources of autoantigens and danger or damage associated molecular patterns, directly damage tissues, and exaggerate complement activity and inflammation. This review focusses on the understanding of NETs from their formation to their functions in both physiological and pathological processes.

Neutrophil extracellular traps in systemic autoimmune and autoinflammatory diseases

Systemic autoimmune diseases are characterized by the failure of the immune system to differentiate self from non-self. These conditions are associated with significant morbidity and mortality, and they can affect many organs and systems, having significant clinical heterogeneity. Recent discoveries have highlighted that neutrophils, and in particular the neutrophil extracellular traps that they can release upon activation, can have central roles in the initiation and perpetuation of systemic autoimmune disorders and orchestrate complex inflammatory responses that lead to organ damage. Dysregulation of neutrophil cell death can lead to the modification of autoantigens and their presentation to the adaptive immune system. Furthermore, subsets of neutrophils that seem to be more prevalent in patients with systemic autoimmune disorders can promote vascular damage and increased oxidative stress. With the emergence of new technologies allowing for improved assessments of neutrophils, the complexity of neutrophil biology and its dysregulation is now starting to be understood. In this Review, we provide an overview of the roles of neutrophils in systemic autoimmune and autoinflammatory diseases and address putative therapeutic targets that may be explored based on this new knowledge.

Dysregulated miRNAs network in the critical COVID-19: An important clue for uncontrolled immunothrombosis/thromboinflammation

Known as a pivotal immunohemostatic response, immunothrombosis is activated to restrict the diffusion of pathogens. This beneficial intravascular defensive mechanism represents the close interaction between the immune and coagulation systems. However, its uncontrolled form can be life-threatening to patients with the critical coronavirus disease 2019 (COVID-19). Hyperinflammation and ensuing cytokine storm underlie the activation of the coagulation system, something which results in the provocation of more immune-inflammatory responses by the thrombotic mediators. This vicious cycle causes grave clinical complications and higher risks of mortality. Classified as an evolutionarily conserved family of the small non-coding RNAs, microRNAs (miRNAs) serve as the fine-tuners of genes expression and play a key role in balancing the pro/anticoagulant and pro-/anti-inflammatory factors maintaining homeostasis. Therefore, any deviation from their optimal expression levels or efficient functions can lead to severe complications. Despite their extensive effects on the molecules and processes involved in uncontrolled immunothrombosis, some genetic agents and uncontrolled immunothrombosis-induced interfering factors (e.g., miRNA-single nucleotide polymorphysms (miR-SNPs), the complement system components, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, and reactive oxygen species (ROS)) have apparently disrupted their expressions/functions. This review study aims to give an overview of the role of miRNAs in the context of uncontrolled immunothrombosis/thromboinflammation accompanied by some presumptive interfering factors affecting their expressions/functions in the critical COVID-19. Detecting, monitoring, and resolving these interfering agents mafy facilitate the design and development of the novel miRNAs-based therapeutic approaches to the reduction of complications incidence and mortality in patients with the critical COVID-19.

Neutrophil extracellular traps facilitate cancer metastasis: cellular mechanisms and therapeutic strategies

Background

The formation of neutrophil extracellular traps (NETs) was initially discovered as a novel immune response against pathogens. Recent studies have also suggested that NETs play an important role in tumor progression. This review summarizes the cellular mechanisms by which NETs promote distant metastasis and discusses the possible clinical applications targeting NETs.

Method

The relevant literature from PubMed and Google Scholar (2001–2021) have been reviewed for this article.

Results

The presence of NETs has been detected in various primary tumors and metastatic sites. NET-associated interactions have been observed throughout the different stages of metastasis, including initial tumor cell detachment, intravasation and extravasation, the survival of circulating tumor cells, the settlement and the growth of metastatic tumor cells. Several in vitro and in vivo studies proved that inhibiting NET formation resulted in anti-cancer effects. The biosafety and efficacy of some NET inhibitors have also been demonstrated in early phase clinical trials.

Conclusions

Considering the role of NETs in tumor progression, NETs could be a promising diagnostic and therapeutic target for cancer management. However, current evidence is mostly derived from experimental models and as such more clinical studies are still needed to verify the clinical significance of NETs in oncological settings.

Neutrophil-to-lymphocyte ratio as an independent inflammatory indicator for poor renal prognosis in adult IgA vasculitis with nephritis

BACKGROUND

Skin-limited IgAV patients usually present self-limiting disease and good prognosis, while adult IgA vasculitis with nephritis (IgAV-N) present severe phenotype and poor prognosis. Previous studies showed that neutrophil-to-lymphocyte ratio (NLR) was an inflammatory indicator for predicting systemic involvement in children IgAV patients. In this study, we focused on adult IgAV-N patients to explore the relationship of NLR with disease phenotype and long-term renal prognosis.

METHODS

In this study, 245 IgAV-N patients, 1151 IgAN patients and 251 healthy controls were recruited. Composite endpoint was defined as 30% eGFR declined or end stage kidney disease.

RESULTS

IgAV-N patients presented increased white blood cells (WBC), neutrophils (NE), platelet-to-lymphocyte ratio (PLR), and NLR levels, while decreased lymphocyte (LY) than healthy controls. When compared to clinical and pathological features matched IgAN patients, IgAV-N patients still showed higher WBC, NE, and NLR levels. NLR showed the best performance for the diagnosis of IgAV-N with the highest area under the ROC curves (0.738). IgAV-N patients in high NLR group (>2.41) presented with sever baseline manifestations and more acute pathological lesions than low NLR group (≤2.41). 77 patients with regular follow-up were used for survival analysis. After adjusting some well-known risk factors, NLR levels remained as an independent risk factor for poor renal outcome in adult patients with IgAV-N (HR, 1.913; 95% CI, 1.314 to 2.787, P = 0.001).

CONCLUSIONS

NLR levels were associated with the clinical and pathological phenotypes, and NLR may serve as an independent risk factor for poor renal outcome in adult IgAV-N patients.

Recent Developments in the Understanding of Immunity, Pathogenesis and Management of COVID-19

Coronaviruses represent a diverse family of enveloped positive-sense single stranded RNA viruses. COVID-19, caused by Severe Acute Respiratory Syndrome Coronavirus-2, is a highly contagious respiratory disease transmissible mainly via close contact and respiratory droplets which can result in severe, life-threatening respiratory pathologies. It is understood that glutathione, a naturally occurring antioxidant known for its role in immune response and cellular detoxification, is the target of various proinflammatory cytokines and transcription factors resulting in the infection, replication, and production of reactive oxygen species. This leads to more severe symptoms of COVID-19 and increased susceptibility to other illnesses such as tuberculosis. The emergence of vaccines against COVID-19, usage of monoclonal antibodies as treatments for infection, and implementation of pharmaceutical drugs have been effective methods for preventing and treating symptoms. However, with the mutating nature of the virus, other treatment modalities have been in research. With its role in antiviral defense and immune response, glutathione has been heavily explored in regard to COVID-19. Glutathione has demonstrated protective effects on inflammation and downregulation of reactive oxygen species, thereby resulting in less severe symptoms of COVID-19 infection and warranting the discussion of glutathione as a treatment mechanism.

Dysregulation of neutrophil death in sepsis

Sepsis is a prevalent disease that has alarmingly high mortality rates and, for several survivors, long-term morbidity. The modern definition of sepsis is an aberrant host response to infection followed by a life-threatening organ dysfunction. Sepsis has a complicated pathophysiology and involves multiple immune and non-immune mediators. It is now believed that in the initial stages of sepsis, excessive immune system activation and cascading inflammation are usually accompanied by immunosuppression. During the pathophysiology of severe sepsis, neutrophils are crucial. Recent researches have demonstrated a clear link between the process of neutrophil cell death and the emergence of organ dysfunction in sepsis. During sepsis, spontaneous apoptosis of neutrophils is inhibited and neutrophils may undergo some other types of cell death. In this review, we describe various types of neutrophil cell death, including necrosis, apoptosis, necroptosis, pyroptosis, NETosis, and autophagy, to reveal their known effects in the development and progression of sepsis. However, the exact role and mechanisms of neutrophil cell death in sepsis have not been fully elucidated, and this remains a major challenge for future neutrophil research. We hope that this review will provide hints for researches regarding neutrophil cell death in sepsis and provide insights for clinical practitioners.

Neutrophils activated by membrane attack complexes increase the permeability of melanoma blood vessels

Cancer cell dissemination is the seed for metastasis and adversely linked to patients’ benefit. Critical for hematogenous dissemination is the entrance of the cancer cell into the circulation, which is regulated by vascular permeability within the primary tumor. Here, we describe pathophysiological communication between endothelial cells, tumor infiltrating neutrophils, and the complement system, with implications for vascular barrier opening and melanoma cell dissemination. Experiments in complement-deficient animals indicate that interference with complement-mediated activation of neutrophils stabilizes blood vessel integrity and abolishes the systemic spread of melanoma cells.

The microenvironment of malignant melanomas defines the properties of tumor blood vessels and regulates infiltration and vascular dissemination of immune and cancer cells, respectively. Previous research in other cancer entities suggested the complement system as an essential part of the tumor microenvironment. Here, we confirm activation of the complement system in samples of melanoma patients and murine melanomas. We identified the tumor endothelium as the starting point of the complement cascade. Generation of complement-derived C5a promoted the recruitment of neutrophils. Upon contact with the vascular endothelium, neutrophils were further activated by complement membrane attack complexes (MACs). MAC-activated neutrophils release neutrophil extracellular traps (NETs). Close to the blood vessel wall, NETs opened the endothelial barrier as indicated by an enhanced vascular leakage. This facilitated the entrance of melanoma cells into the circulation and their systemic spread. Depletion of neutrophils or lack of MAC formation in complement component 6 (C6)–deficient animals protected the vascular endothelium and prevented vascular intravasation of melanoma cells. Our data suggest that inhibition of MAC-mediated neutrophil activation is a potent strategy to abolish hematogenous dissemination in melanoma.