Regulating Neutrophil PAD4/NOX-Dependent Cerebrovasular Thromboinflammation

T-2 toxin triggers immunotoxic effects in goats by inducing ferroptosis and neutrophil extracellular traps

T-2 toxin, a prevalent mycotoxin, represents a notable global public health risk. Neutrophil extracellular traps (NETs) and ferroptosis are involved in a variety of pathophysiological processes and are implicated in goat immunity. However, the impact of T-2 toxin on NETs release, ferroptosis, and their interplay have not been previously documented. In this study, neutrophils were stimulated with T-2 toxin for 4 h. The structure and mechanism of NETs were analyzed using immunofluorescence and Pico Green staining. The expressions of glutathione peroxidase 4 (GPX4) and ferritin (FT) was quantified by qRT-PCR and western blotting. The levels of ROS and lipid ROS were assessed using DCFH-DA and C11 BODIPY 581/591 probes, and cellular mitochondria Fe2+ were detected by using Mito-FerroGreen probe. Inhibitors were utilized to explore the interaction between these two processes. The results confirmed that the T-2 toxin stimulated the NETs production, characterized by a structure co-modified by citrullinated histones (citH3), neutrophil elastase (NE) and DNA. Notably, significant inhibition of NETs production by T-2 toxin was observed with the NOX inhibitor DPI (P < 0.001), the ERK inhibitor U0126 (P < 0.001), the TLR2 inhibitor C29 (P < 0.001), and the TLR4 inhibitor TLR4-IN-C34 (P < 0.001). T-2 toxin triggered ferroptosis in neutrophils by suppressing GPX4 and FT expression, elevating ROS and lipid ROS, and augmenting the concentration of mitochondrial Fe2+. The ferroptosis inhibitor Fer-1 could rescue this induction; however, Fer-1 was unable to inhibit NETs which is induced by T-2 toxin. Conversely, T-2 toxin effectively triggered the downregulation of GPX4, which was counteracted by DPI, U0126, C29, and C34. This research elucidates the immunotoxic mechanisms of T-2 toxin in goat neutrophils and offers a novel perspective on preventing and treating T-2 toxin.

Neutrophil Extracellular Trap Formation Model Induced by Monosodium Urate and Phorbol Myristate Acetate: Involvement in MAPK Signaling Pathways

Neutrophil extracellular traps (NETs) formation is a key process in inflammatory diseases like gout, but the underlying molecular mechanisms remain incompletely understood. This study aimed to establish a model to examine the formation of NETs induced by monosodium urate (MSU) and phorbol 12-myristate 13-acetate (PMA) and to elucidate their molecular pathways. Laser confocal microscopy was used to visualize NET formation, while flow cytometry was employed to detect reactive oxygen species (ROS) production. The microstructure of neutrophils was observed by transmission electron microscopy, and the expression of key proteins was determined by Western blotting. Additionally, the effect of various inhibitors targeting the MAPK signaling pathway on NET formation was evaluated. They include the Ras inhibitor Salirasib, Raf inhibitor Vemurafenib, ERK inhibitor PD98059, and p38 MAPK inhibitor SB203580, as well as NADPH oxidase inhibitor DPI and neutrophil elastase inhibitor Alvelestat. The results showed that MSU and PMA triggered significant NET formation, which was accompanied by increased ROS levels, lactate dehydrogenase release, dsDNA, and IL-8. Notably, selective MAPK pathway inhibitors and DPI and Alvelestat, except for SB203580, effectively down-regulated these indicators. These data indicated that the activation of a signaling pathway involving Ras-Raf-ERK, which is dependent on ROS, is crucial for the induction of NET formation by MSU and PMA. Given the involvement of NETs in multiple pathologies, our findings could potentially serve as molecular targets for the intervention and treatment of crystal-related diseases, especially for gout.

Type I IFN-mediated NET release promotes Mycobacterium tuberculosis replication and is associated with granuloma caseation

Neutrophils are the most abundant cell type in the airways of tuberculosis patients. Mycobacterium tuberculosis (Mtb) infection induces the release of neutrophil extracellular traps (NETs); however, the molecular regulation and impact of NET release on Mtb pathogenesis are unknown. We find that during Mtb infection in neutrophils, PAD4 citrullinates histones to decondense chromatin that gets released as NETs in a manner that can maintain neutrophil viability and promote Mtb replication. Type I interferon promotes the formation of chromatin-containing vesicles that allow NET release without compromising plasma membrane integrity. Analysis of nonhuman primate granulomas supports a model where neutrophils are exposed to type I interferon from macrophages as they migrate into the granuloma, thereby enabling the release of NETs associated with necrosis and caseation. Our data reveal NET release as a promising target to inhibit Mtb pathogenesis.

Neutrophil extracellular traps in tumor progression of gynecologic cancers

This article delves into the intricate interplay between tumors, particularly gynecologic malignancies, and neutrophil extracellular traps (NETs). The relationship between tumors, specifically gynecologic malignancies, and NETs is a multifaceted and pivotal area of study. Neutrophils, pivotal components of the immune system, are tasked with combating foreign invaders. NETs, intricate structures released by neutrophils, play a vital role in combating systemic infections but also play a role in non-infectious conditions such as inflammation, autoimmune diseases, and cancer. Cancer cells have the ability to attract neutrophils, creating tumor-associated neutrophils, which then stimulate the release of NETs into the tumor microenvironment. The impact of NETs within the tumor microenvironment is profound and intricate. They play a significant role in influencing cancer development and metastasis, as well as modulating tumor immune responses. Through the release of proteases and pro-inflammatory cytokines, NETs directly alter the behavior of tumor cells, increasing invasiveness and metastatic potential. Additionally, NETs can trigger epithelial-mesenchymal transition in tumor cells, a process associated with increased invasion and metastasis. The interaction between tumors and NETs is particularly critical in gynecologic malignancies such as ovarian, cervical, and endometrial cancer. Understanding the mechanisms through which NETs operate in these tumors can offer valuable insights for the development of targeted therapeutic interventions. Researchers are actively working towards harnessing this interaction to impede tumor progression and metastasis, opening up new avenues for future treatment modalities. As our understanding of the interplay between tumors and NETs deepens, it is anticipated that novel treatment strategies will emerge, potentially leading to improved outcomes for patients with gynecologic malignancies. This article provides a comprehensive overview of the latest research findings on the interaction between NETs and cancer, particularly in gynecologic tumors, serving as a valuable resource for future exploration in this field.

Mast cell extracellular trap formation underlies vascular and neural injury and hyperalgesia in sickle cell disease

Sickle cell disease (SCD) is the most common inherited monogenetic disorder. Chronic and acute pain are hallmark features of SCD involving neural and vascular injury and inflammation. Mast cells reside in the vicinity of nerve fibers and vasculature, but how they influence these structures remains unknown. We therefore examined the mechanism of mast cell activation in a sickle microenvironment replete with cell-free heme and inflammation. Mast cells exposed to this environment showed an explosion of nuclear contents with the release of citrullinated histones, suggestive of mast cell extracellular trap (MCET) release. MCETs interacted directly with the vasculature and nerve fibers, a cause of vascular and neural injury in sickle cell mice. MCET formation was dependent upon peptidylarginine deiminase 4 (PAD4). Inhibition of PAD4 ameliorated vasoocclusion, chronic and acute hyperalgesia, and inflammation in sickle mice. PAD4 activation may also underlie neutrophil trap formation in SCD, thus providing a novel target to treat the sequelae of vascular and neural injury in SCD.

Immunothrombosis: A bibliometric analysis from 2003 to 2023

BACKGROUND

Immunothrombosis is a physiological process that constitutes an intravascular innate immune response. Abnormal immunothrombosis can lead to thrombotic disorders. With the outbreak of COVID-19, there is increasing attention to the mechanisms of immunothrombosis and its critical role in thrombotic events, and a growing number of relevant research papers are emerging. This article employs bibliometrics to discuss the current status, hotspots, and trends in research of this field.

METHODS

Research papers relevant to immunothrombosis published from January 1, 2003, to May 29, 2023, were collected from the Web of Science Core Collection database. VOSviewer and the R package "Bibliometrix" were employed to analyze publication metrics, including the number of publications, authors, countries, institutions, journals, and keywords. The analysis generated visual results, and trends in research topics and hotspots were examined.

RESULTS

A total of 495 target papers were identified, originating from 58 countries and involving 3287 authors from 1011 research institutions. Eighty high-frequency keywords were classified into 5 clusters. The current key research topics in the field of immunothrombosis include platelets, inflammation, neutrophil extracellular traps, Von Willebrand factor, and the complement system. Research hotspots focus on the mechanisms and manifestations of immunothrombosis in COVID-19, as well as the discovery of novel treatment strategies targeting immunothrombosis in cardiovascular and cerebrovascular diseases.

CONCLUSION

Bibliometric analysis summarizes the main achievements and development trends in research on immunothrombosis, offering readers a comprehensive understanding of the field and guiding future research directions.

Artificial intelligence-driven multiomics predictive model for abdominal aortic aneurysm subtypes to identify heterogeneous immune cell infiltration and predict disease progression

BACKGROUND

Abdominal aortic aneurysm (AAA) poses a significant health risk and is influenced by various compositional features. This study aimed to develop an artificial intelligence-driven multiomics predictive model for AAA subtypes to identify heterogeneous immune cell infiltration and predict disease progression. Additionally, we investigated neutrophil heterogeneity in patients with different AAA subtypes to elucidate the relationship between the immune microenvironment and AAA pathogenesis.

METHODS

This study enrolled 517 patients with AAA, who were clustered using k-means algorithm to identify AAA subtypes and stratify the risk. We utilized residual convolutional neural network 200 to annotate and extract contrast-enhanced computed tomography angiography images of AAA. A precise predictive model for AAA subtypes was established using clinical, imaging, and immunological data. We performed a comparative analysis of neutrophil levels in the different subgroups and immune cell infiltration analysis to explore the associations between neutrophil levels and AAA. Quantitative polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay were performed to elucidate the interplay between CXCL1, neutrophil activation, and the nuclear factor (NF)-κB pathway in AAA pathogenesis. Furthermore, the effect of CXCL1 silencing with small interfering RNA was investigated.

RESULTS

Two distinct AAA subtypes were identified, one clinically more severe and more likely to require surgical intervention. The CNN effectively detected AAA-associated lesion regions on computed tomography angiography, and the predictive model demonstrated excellent ability to discriminate between patients with the two identified AAA subtypes (area under the curve, 0.927). Neutrophil activation, AAA pathology, CXCL1 expression, and the NF-κB pathway were significantly correlated. CXCL1, NF-κB, IL-1β, and IL-8 were upregulated in AAA. CXCL1 silencing downregulated NF-κB, interleukin-1β, and interleukin-8.

CONCLUSION

The predictive model for AAA subtypes demonstrated accurate and reliable risk stratification and clinical management. CXCL1 overexpression activated neutrophils through the NF-κB pathway, contributing to AAA development. This pathway may, therefore, be a therapeutic target in AAA.

Neutrophil extracellular traps mediate neuro-immunothrombosis

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

The role of extracellular traps released by neutrophils, eosinophils, and macrophages in asthma

Extracellular traps (ETs) are a specialized form of innate immune defense in which leukocytes release ETs composed of chromatin and active proteins to eliminate pathogenic microorganisms. In addition to the anti-infection effect of ETs, researchers have also discovered their involvement in the pathogenesis of inflammatory disease, tumors, autoimmune disease, and allergic disease. Asthma is a chronic airway inflammatory disease involving multiple immune cells. The increased level of ETs in asthma patients suggests that ETs play an important role in the pathogenesis of asthma. Here we review the research work on the formation mechanism, roles, and therapeutic strategies of ETs released by neutrophils, eosinophils, and macrophages in asthma.

A promising frontier: targeting NETs for stroke treatment breakthroughs

Stroke is a prevalent global acute cerebrovascular condition, with ischaemic stroke being the most frequently occurring type. After a stroke, neutrophils accumulate in the brain and subsequently generate and release neutrophil extracellular traps (NETs). The accumulation of NETs exacerbates the impairment of the blood‒brain barrier (BBB), hampers neovascularization, induces notable neurological deficits, worsens the prognosis of stroke patients, and can facilitate the occurrence of t-PA-induced cerebral haemorrhage subsequent to ischaemic stroke. Alternative approaches to pharmacological thrombolysis or endovascular thrombectomy are being explored, and targeting NETs is a promising treatment that warrants further investigation.

NADPH-oxidases as potential pharmacological targets for thrombosis and depression comorbidity

There is a complex interrelationship between the nervous system and the cardiovascular system. Comorbidities of cardiovascular diseases (CVD) with mental disorders, and vice versa, are prevalent. Adults with mental disorders such as anxiety and depression have a higher risk of developing CVD, and people with CVD have an increased risk of being diagnosed with mental disorders. Oxidative stress is one of the many pathways associated with the pathophysiology of brain and cardiovascular disease. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is one of the major generators of reactive oxygen species (ROS) in mammalian cells, as it is the enzyme that specifically produces superoxide. This review summarizes recent findings on the consequences of NOX activation in thrombosis and depression. It also discusses the therapeutic effects and pharmacological strategies of NOX inhibitors in CVD and brain disorders. A better comprehension of these processes could facilitate the development of new therapeutic approaches for the prevention and treatment of the comorbidity of thrombosis and depression.

Reducing Abdominal Aortic Aneurysm Progression by Blocking Neutrophil Extracellular Traps Depends on Thrombus Formation

Neutrophil extracellular traps (NETs) are implicated in the pathogenesis of abdominal aortic aneurysm (AAA), located in adventitia and intraluminal thrombus. We compared the therapeutic potential of targeting upstream or downstream effector molecules of NET formation in 2 murine AAA models based on angiotensin II or peri-adventitial elastase application. In both models, NETs were detected in formed aneurysms at treatment start. Although NET inhibitors failed in the elastase model, they prevented progression of angiotensin II-induced aneurysms with thrombus, which resembles established human disease (including thrombus development). Blockade of upstream NET mediators was more effective than interference with downstream NET molecules.

NETosis: Sculpting tumor metastasis and immunotherapy

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

Eosinophil extracellular traps in asthma: implications for pathogenesis and therapy

Asthma is a common, chronic inflammatory disease of the airways that affects millions of people worldwide and is associated with significant healthcare costs. Eosinophils, a type of immune cell, play a critical role in the development and progression of asthma. Eosinophil extracellular traps (EETs) are reticular structures composed of DNA, histones, and granulins that eosinophils form and release into the extracellular space as part of the innate immune response. EETs have a protective effect by limiting the migration of pathogens and antimicrobial activity to a controlled range. However, chronic inflammation can lead to the overproduction of EETs, which can trigger and exacerbate allergic asthma. In this review, we examine the role of EETs in asthma.

The invisible string of coagulation, complement, iron, and inflammation in sickle cell disease

PURPOSE OF REVIEW

This review provides an update on recent advances in mechanistic studies of thromboinflammatory mechanisms that contribute to the disease pathology in sickle cell disease (SCD). There is a focus on novel pathways, clinical relevance, and translational potential of these findings. We hope to encourage more advances in this area to reduce organ damage in young patients prior to gene therapy, and to serve the aging SCD patient population.

RECENT FINDINGS

Novel insights into the roles of neutrophils, the ADAMTS-13/VWF axis, oxidative stress, and the intrinsic coagulation cascade, as well as relevant clinical trials, are discussed.

SUMMARY

Several studies implicate dysregulation of the ADAMTS-13/VWF axis as playing a major role in vaso-occlusive events (VOE) in SCD. Another highlight is reducing iron overload, which has beneficial effects on erythrocyte and neutrophil function that reduce VOE and inflammation. Multiple studies suggest that targeting HO-1/ROS in erythrocytes, platelets, and endothelium can attenuate disease pathology. New insights into coagulation activation identify intrinsic coagulation factor XII as a central regulator of many thromboinflammatory pathologies in SCD. The complement cascade and modulators of neutrophil function and release of neutrophil extracellular traps are also discussed.

IκB kinase β (IKKβ): Structure, transduction mechanism, biological function, and discovery of its inhibitors

The effective approach to discover innovative drugs will ask natural products for answers because of their complex and changeable structures and multiple biological activities. Inhibitory kappa B kinase beta (IKKβ), known as IKK2, is a key regulatory kinase responsible for the activation of NF-κB through its phosphorylation at Ser177 and Ser181 to promote the phosphorylation of inhibitors of kappa B (IκBs), triggering their ubiquitination and degradation to active the nuclear factor kappa-B (NF-κB) cascade. Chemical inhibition of IKKβ or its genetic knockout has become an effective method to block NF-κB-mediated proliferation and migration of tumor cells and inflammatory response. In this review, we summarized the structural feature and transduction mechanism of IKKβ and the discovery of inhibitors from natural resources (e.g. sesquiterpenoids, diterpenoids, triterpenoids, flavonoids, and alkaloids) and chemical synthesis (e.g. pyrimidines, pyridines, pyrazines, quinoxalines, thiophenes, and thiazolidines). In addition, the biosynthetic pathway of novel natural IKKβ inhibitors and their biological potentials were discussed. This review will provide inspiration for the structural modification of IKKβ inhibitors based on the skeleton of natural products or chemical synthesis and further phytochemistry investigations.

Poststroke venous thromboembolism and neutrophil activation: an illustrated review

Patients with acute ischemic stroke are at a high risk of venous thromboembolism (VTE), such as deep vein thrombosis (DVT), estimated to affect approximately 80,000 patients with stroke each year in the United States. The prevalence of symptomatic DVT after acute stroke is approximately 10%. VTE is associated with increased rates of in-hospital death and disability, with higher prevalence of in-hospital complications and increased 1-year mortality in patients with stroke. Current guidelines recommend the use of pharmacologic VTE prophylaxis in patients with acute ischemic stroke. However, thromboprophylaxis prevents only half of expected VTE events and is associated with high risk of bleeding, suggesting the need for targeted alternative treatments to reduce VTE risk in these patients. Neutrophils are among the first cells in blood to respond after ischemic stroke. Importantly, coordinated interactions among neutrophils, platelets, and endothelial cells contribute to the development of DVT. In case of stroke and other related immune disorders, such as antiphospholipid syndrome, neutrophils potentiate thrombus propagation through the formation of neutrophil-platelet aggregates, secreting inflammatory mediators, complement activation, releasing tissue factor, and producing neutrophil extracellular traps. In this illustrated review article, we present epidemiology and management of poststroke VTE, preclinical and clinical evidence of neutrophil hyperactivation in stroke, and mechanisms for neutrophil-mediated VTE in the context of stroke. Given the hyperactivation of circulating neutrophils in patients with stroke, we propose that a better understanding of molecular mechanisms leading to neutrophil activation may result in the development of novel therapeutics to reduce the risk of VTE in this patient population.