Search Results (783)

Cardiovascular diseases (CVDs) are increasingly being defined not only in terms of metabolic or purely vascular disorders, but also as complex immunometabolic disorders. One of the most groundbreaking discoveries in recent years is the role of neutrophil extracellular networks (NETs/NENs) as a key link between chronic vascular wall inflammation and thrombotic processes. In this article, we present a synthetic overview of the latest data on the biology of NETs/NENs and their impact on the development of atherosclerosis, endothelial dysfunction, and the mechanisms of immunothrombosis. We highlight how these structures contribute to the weakening of atherosclerotic plaque stability, impaired endothelial barrier integrity, platelet activation, and the initiation of the coagulation cascade. We also discuss the modulating role of classic risk factors such as hypertension, dyslipidemia, and exposure to tobacco smoke, which may increase the formation or hinder the elimination of NETs/NENs. We also focus on the practical application of this knowledge: we present biomarkers associated with the presence of NETs/NENs (cfDNA, MPO–DNA complexes, CitH3, NE), which may be useful in diagnostics and risk stratification, and we discuss innovative therapeutic strategies. In addition to classic methods for indirectly inhibiting NET/NEN formation (antiplatelet, anti-inflammatory, and immunometabolic agents), we present experimental approaches aimed at their neutralization and removal (e.g., DNase I, elastase, and myeloperoxidase inhibitors). We pay particular attention to the context of cardiac and cardiac surgical procedures (Percutaneous Coronary Intervention-PCI, coronary artery bypass grafting-CABG), where rapid NET/NEN bursts can increase the risk of acute thrombotic complications. The overall evidence indicates that NETs/NENs represent an innovative and promising research and therapeutic target, allowing us to view cardiovascular diseases in a new light—as a dynamic interaction of inflammatory, atherosclerotic, and thrombotic processes. This opens up new possibilities in diagnostics, combination treatment and personalisation of therapy, although further research and standardization of detection methods remain necessary. Full article

Neutrophils are an essential protective component of the innate immune system. However, in severe bacterial infections, neutrophils are known to mis-localise from the primary site of infection to other organs, where excessive release of cytokines, chemokines, and neutrophil extracellular traps (NETs) can induce organ damage and death. In this study, we use an animal model of bacterial infection originating in the peritoneum to show that hydrogen peroxide (H₂O₂, a potent neutrophil chemoattractant) is initially released in high concentrations both in the peritoneum and in multiple ‘off-target’ organs (lungs, liver and kidneys). The initial high H₂O₂ release inhibits neutrophil chemotaxis, but after 24 h concentrations of H₂O₂ reduce and can promote neutrophil migration to organs, where they release pro-inflammatory cytokines and chemokines along with NETs. The antimalarial compound artesunate potently inhibits neutrophil migration to off-target organs. It also abolishes cytokine, chemokine, and NET production, suggesting that artesunate may be a valuable novel therapy for preventing off-target organ inflammation associated with severe bacterial infections. Finally, the potency of H₂O₂ as a chemoattractant is shown by in vitro experiments in which, faced with competing gradients of H₂O₂ and other chemoattractants, neutrophils preferentially migrate towards H₂O₂. Full article

Neutrophils are the most abundant immune cells in the human body. Neutrophil extracellular traps (NETs) have recently garnered significant attention as a novel, non-traditional mechanism for combating pathogenic microorganisms. Recent studies have shown that NETs play a crucial role in antiviral immunity, providing new perspectives on how neutrophils defend against viral invasion. Viruses not only induce NET formation through various mechanisms but have also developed multiple escape strategies targeting NETs. It is worth noting that NETs are a double-edged sword for the host: while they possess antiviral effects that inhibit viral spread and replication, their constituent components may also exacerbate tissue damage and play important pathological roles in the progression of certain viral infections. Therefore, a thorough understanding of the regulatory mechanisms and dynamic balance of NETs in viral infections is of critical importance. Additionally, since the components of NETs may vary depending on the stimulus, NET-related markers have the potential to serve as biomarkers for the severity and prognosis of viral diseases. This article provides a systematic review of the induction mechanisms, antiviral effects, viral escape strategies, and virus-induced NET-related immunopathological damage in viral infections, offering new insights for antiviral immunotherapy. Full article

Endothelial dysfunction is an early driver of atherosclerosis, yet the direct impact of endogenous crystals such as cholesterol crystals and monosodium urate on endothelial activation remains incompletely understood. In this study, we examine how crystalline stimuli modulate human umbilical vein endothelial cells by assessing inflammatory signaling, mitochondrial respiration, and neutrophil recruitment. Using dose- and time-controlled experiments, we show that CC and MSU are internalized by endothelial cells, activating NF-κB and STAT3 signaling pathways and inducing a robust pro-inflammatory cytokine profile. Notably, CC caused marked mitochondrial dysfunction, evidenced by impaired respiratory capacity and loss of membrane potential, revealing a novel bioenergetic vulnerability in endothelial cells. Both direct crystal stimulation and exposure to crystal-primed conditioned media triggered endothelial adhesion molecule expression and promoted neutrophil adhesion, indicating that soluble mediators released upon crystal stimulation can propagate vascular inflammation. These findings demonstrate that crystalline stimuli are potent vascular danger signals capable of driving endothelial inflammation, mitochondrial impairment, and immune cell engagement, which are hallmarks of early atherogenesis. By elucidating these multifaceted endothelial responses, this study provides important mechanistic insights into how crystal-induced signals may contribute to vascular dysfunction and the early stages of atherogenesis. Full article

Eosinophils are innate immune cells that infiltrate tissues in response to cell proliferation and necrosis, which occurs during normal injury repair, parasitic infections, allergies, and cancer. Their involvement in cancer is controversial particularly with regard to tumor-associated tissue eosinophilia (TATE) and a recently defined mechanism of extracellular trap cell death (ETosis), a particular type of eosinophil cell death that is distinct from both apoptosis and necrosis. This narrative review synthesizes the literature regarding the prognostic significance of TATE, focusing on eosinophil ETosis and the important role of transmission electron microscopy (TEM) in its detection and morphological characterization. The prognostic role of TATE is contradictory: in certain tumors, it is a favorable prognostic marker, while in others, it is unfavorable. However, recent research reveals that TATE is associated with a better prognosis in non-viral neoplasms, but it may correlate with a poor prognosis in virus-related neoplasms, such as human T-lymphotropic virus type 1 (HTLV-1)-associated lymphomas and HPV-positive carcinomas. Our ultrastructural investigations revealed distinct phases of eosinophil ETosis in gastric cancer, which were defined by chromatin decondensation, plasma membrane disruption, granule discharge, and development of extracellular traps. We observed synapse-like interactions between eosinophils, exhibiting ETosis or compound exocytosis, and tumor cells, which showed various degrees of cellular damage, ultimately leading to colloid-osmotic tumor cell death. TEM provides important insights into eosinophil-mediated cytotoxicity, requiring further investigation as potential immune effector mechanisms in non-viral tumors. TATE evaluation, together with the viral status of the neoplasia, may be useful to confirm its prognostic significance and consequently its therapeutic implication in specific cancers. Full article

Immune cells like neutrophils, monocytes/macrophages, and lymphocytes play key roles in the development, progression, and resolution of deep vein thrombosis (DVT) by contributing to inflammation, coagulation, and fibrinolysis. IFN-γ, a cytokine mainly secreted by natural killer (NK) and T cells, is a critical factor in DVT pathogenesis. It links immune responses to coagulation activation by promoting endothelial activation, leukocyte recruitment, cytokine release, and coagulation imbalance. Its strong pro-inflammatory and prothrombotic effects make IFN-γ a promising target for DVT treatment beyond standard anticoagulants. Exploring ways to block IFN-γ signaling or its downstream effects could open doors to novel therapies for DVT, aiding in resolution and preventing post-thrombotic complications. This review delves into DVT pathophysiology, diagnostics, and management, emphasizing the importance of targeting immune cells and IFN-γ to advance treatment options. Full article

Legionella pneumophila (L. pneumophila) infection is characterized by a wide spectrum of manifestations, from influenza-like illness to life-threatening atypical pneumonia with multiorgan failure. The aim of our study was the assessment of in vitro and ex vivo neutrophil activation in L. pneumophila infections, as well as the role of neutrophils’ peptides such as LL-37 in infection. The ability of neutrophils to form ex vivo extracellular traps (NETs) in response to bacterial infection was examined by immunofluorescence. In parallel, patients’ sera, as well as opsonized standard L. pneumophila strains, were used for in vitro activation of neutrophils from healthy individuals. The serum levels of interleukins were assessed using the LEGENDplexTM Multi-Analyte Flow Assay Kit. Furthermore, citrullinated cf-DNA as a marker of neutrophil extracellular traps (NETs) was detected in the serum of patients with acute infection. It was demonstrated that neutrophils released NETs in vitro and ex vivo upon L. pneumophila (interaction in an autophagy-independent manner. Notably, IL-1b was detected on NETs, but an antimicrobial peptide LL-37 was absent. The lack of antimicrobial activity failed to inhibit bacterial proliferation. In addition, in vitro and ex vivo NETs formation was observed during the Clarithromycin treatment. Those NETs were decorated with bioactive antimicrobial peptide LL-37, which inhibits bacterial proliferation. The findings provide evidence that neutrophils release NETs in vitro and ex vivo by expressing the IL1β protein in them. The lack of expression of the antimicrobial peptide LL-37 on the NETs demonstrates the inability of the cells to inhibit proliferation, and consequently the elimination of L. pneumophila. Clarithromycin plays a dual role in the elimination. Full article

Background: Multiple mechanisms might lead to cancer-related hypercoagulability. In brain tumors, podoplanin, via its ability to activate platelets, seems to play a crucial role in developing venous thromboembolism (VTE). Different stimuli (including activated platelets) can trigger the release of prothrombotic neutrophil extracellular traps (NETs) by neutrophils. It remains to be elucidated whether podoplanin-induced platelet aggregates might also impact NET formation and subsequent hypercoagulability and thrombosis. Methods: Patients with glioma were enrolled in this prospective observational cohort study. The primary endpoint was VTE. Immunohistochemical staining of NETs (via citrullinated histone H3 [H3Cit]) and neutrophils (via myeloperoxidase [MPO]) was conducted in glioma specimens and correlated with intravascular platelet clusters (via CD61) and podoplanin. Results: In total, 154 patients were included. H3Cit+ tumor vessels were found in 45/154 cases. H3Cit were significantly associated with increased intravascular platelet clusters (CD61− vs. CD61+ vs. CD61++ vs. CD61+++: 3.7% (1/27) vs. 18.6% (11/59) vs. 39.4% (13/33) vs. 57.1% (20/35), p < 0.001) and podoplanin expression (PDPN− vs. PDPN+: 14.3% (7/49) vs. 36.2% (38/105), p = 0.007) in the tumor tissue. Furthermore, H3Cit+ tumor vessels were significantly associated with tumor-infiltrating MPO+ neutrophils (H3Cit− vs. H3Cit+, median [Q1-Q3]: 6.0 [3.3–12.3] vs. 12.5 [5.9–22.0] cells/mm², p < 0.001) and with D-dimer levels (H3Cit− vs. H3Cit+: 0.53 [0.32–1.10] vs. 0.84 [0.46–2.75] µg/mL, p = 0.034). The VTE risk was not linked to H3Cit+ tumor vessels (p = 0.613, log-rank). Conclusions: H3Cit in tumor vessels was not associated with VTE. However, H3Cit was linked to a local procoagulant phenotype in glioma, thereby potentially contributing to a systemic hypercoagulable state and thrombus formation. Full article

Background/Objectives: Eosinophilic myocarditis (EM) is a rare, life-threatening inflammatory cardiomyopathy driven by eosinophil cytotoxicity and extracellular trap formation. Interleukin-5 (IL-5) inhibition may disrupt this pathogenic cascade. We reviewed contemporary evidence on IL-5 blockade in EM and contextualized it with an illustrative case. Methods: We searched PubMed through May 2025 for reports of EM treated with mepolizumab or benralizumab. Inclusion criteria were consistent with prior cohorts: acute cardiac symptoms with biomarker elevation plus abnormalities on transthoracic echocardiography and/or cardiac magnetic resonance imaging (CMR), along with documented IL-5-targeted therapy. We extracted clinical, imaging, biopsy, treatment-timing, and outcome data and included one institutional case. Results: Twenty-one episodes were analyzed (median age, 45 years; 10 men). Underlying conditions included eosinophilic granulomatosis with polyangiitis (10 cases; 48%), hypereosinophilic syndrome (5 cases; 24%), drug reaction with eosinophilia and systemic symptoms (DRESS, 3 cases; 14%), and eosinophilic asthma (3 cases; 14%). Treatments involved mepolizumab in 17 cases (81%) and benralizumab in 4 (19%); 4 patients received “early-start” therapy within 14 days of EM diagnosis. Among the 11 episodes with reported left ventricular ejection fraction (LVEF) at baseline and follow-up, the median baseline LVEF was 40% (range, 30–62), with 10 of 11 (91%) <50%. On follow-up, all 11 patients improved: 4 normalized (≥50%) and 7 improved to 40–49%. CMR (n = 18) demonstrated late gadolinium enhancement in 14 cases (78%), edema in 9 (50%), and intracardiac thrombus in 4 (22%). Endomyocardial biopsy confirmed eosinophilic infiltration in 13 of 15 cases (87%). Outcomes included one death (fulminant DRESS), one recovery following veno-arterial extracorporeal membrane oxygenation, and one successful heart transplantation. Illustrative case: A 24-year-old man on a steroid taper received mepolizumab 300 mg on Day 4. His LVEF improved from 47% to 59% by Day 15, accompanied by biomarker decline and successful steroid tapering. Conclusions: Across published cases and our institutional experience, IL-5–targeted therapy appears safe, steroid-sparing, and associated with rapid ventricular recovery, particularly when initiated early. Although limited, these findings support the need for prospective trials to define the optimal agent, dosing, timing, and integration with standard immunosuppression and anticoagulation. Full article

Upon activation, neutrophils perform three distinct functions: phagocytosis, degranulation of antimicrobial substances into the extracellular medium, and release of neutrophil extracellular traps. Determination of the nuclear area expansion of neutrophils activated to release neutrophil extracellular traps has become critical in demonstrating early neutrophil activation and has become standard. Here, we demonstrate an automated method for measuring nuclear area expansion in two different mammalian species: canine and bovine. For both species, neutrophils were isolated from peripheral blood and co-incubated with fresh spermatozoa for up to 120 min for canine neutrophil–spermatozoa and recently thawed cryopreserved spermatozoa up to 240 min for bovine neutrophil–spermatozoa. Fluorescence images were acquired using a TissueFAXS microscope and then analyzed using StrataQuest v.7.0 software. The images show the release of neutrophil extracellular traps upon activation with spermatozoa for both species, as evidenced by the co-localization of neutrophil elastase and DNA staining. Neutrophil nuclei were expanded as early as 15 min and were detected at up to 120 min in both species. Analysis by nuclei segmentation showed that the data sets generated for both species were reliable and consistent with previously published methods. The method was developed as an automated alternative for measuring the area expansion of neutrophil nuclei in different species. Full article

Neutrophils, a first-line defender, has a multifaceted presence in chronic inflammation, autoimmune pathology, and tumor progression. The microenvironmental cues facilitate functional plasticity and phenotypic heterogeneity to neutrophils that enable both their protective and pathogenic roles. Autoimmune diseases including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and juvenile idiopathic arthritis (JIA) display the presence of dysregulated subsets of neutrophil, such as low-density granulocytes (LDGs) that promote proinflammation and contribute to tissue damage via NETosis and type I interferon-mediated signaling. In cancer, particularly tumors, they exhibit tumor-associated neutrophils (TANs) which may polarize either towards anti-tumorigenic ‘N1’ or pro-tumorigenic ‘N2’ phenotypes based on available modulators such as TGF-β and leucine-driven epigenetic modifications. The development in neutrophil biology has introduced several novel therapeutic strategies that allow NET targeting, inhibition of chemokine receptors like CXCR2, and exploration of neutrophil-derived biomarkers for diagnosis and disease monitoring. Such findings encourage the importance of neutrophils as both effectors and therapeutic targets in inflammatory and neoplastic conditions. Full article

Lupus nephritis (LN) is a serious complication of systemic lupus erythematosus that is associated with long-term morbidity and mortality. Pathomorphological findings of LN are broadly divided into proliferative lupus nephritis (PLN) and membranous lupus nephritis (MLN). PLN is characterized by diffuse global or segmental proliferative glomerulonephritis with significant infiltration of inflammatory cells. Type 1 T-helper (Th1) cells, which predominate under inflammatory conditions, and NETosis, as the process of forming neutrophil extracellular traps (NETs), are key factors in the development of PLN. Meanwhile, MLN is characterized by diffuse membranous nephropathy (MN) with global granular subepithelial immune deposits. MLN patients usually experience massive proteinuria, and occasionally show an unfavorable renal prognosis despite aggressive treatment, similar to PLN patients. Intriguingly, in some instances, MLN patients do not show the general immunoserological characteristics of SLE, such as low serum complement and elevated anti-DNA antibody titers. Several reports have indicated an association between Th2 cell dominance and the development of MLN. Moreover, exostosin 1 (EXT1) and exostosin 2 (EXT2) on the glomerular basement membrane have recently been discovered as novel putative antigens for secondary MN, and have been shown to be up-regulated in patients with MLN. To date, many studies have focused on the dissimilarities between PLN and MLN. However, the reason for two polar morphological forms existing within the same disease is not completely clear. The present review addresses published observations on this topic in addition to providing our assertion regarding characteristic NETosis and glomerular EXT1/EXT2 expressions between PLN and MLN. Full article

Neutrophils are the first line of defense of the human immune system against pathogens. Photobiomodulation, mediated by mitochondrial photoacceptors such as cytochrome c oxidase, has emerged as a method to modulate neutrophil function through targeted light exposure. Despite the extensive characterization of neutrophil extracellular traps (NETs) formation (NETosis), the wavelength-specific modulation of neutrophil photoactivation and the involvement of redox pathways remain poorly defined. In this study, the effects of monochromatic (365 nm, 415 nm, 437 nm, and 625 nm) and dichromatic LED-light irradiation on NETs formation were systematically examined. The highest netotic responses were elicited by UV-A (365 nm) and violet-blue light (415 nm), whereas 437 nm showed the lowest induction and 625 nm stimulated a moderate netotic response. The pharmacological inhibition of NETosis induced by 365 nm and 415 nm irradiation with specific NADPH oxidase inhibitor, apocynin, and mitochondrial reactive oxygen species (mtROS) scavenger, MitoTEMPO, attenuated NETs formation by engaging both enzymatic and mitochondrial oxidative sources. Notably, mtROS played a dominant role under 415 nm stimulation in contrast to 365 nm-induced NETosis as demonstrated by higher sensitivity to MitoTEMPO. Importantly, combined simultaneous irradiation with 415 nm and 625 nm LEDs resulted in a significant suppression of NETs formation by more than 50%, highlighting a potent inhibitory synergy observed for the first time and suggesting a new approach of wavelength pairing to modulate neutrophil activation. These results were further supported by measurements of ROS production using a luminol-amplified chemiluminescence assay. Collectively, these findings delineate a wavelength- and ROS-dependent framework for light-induced neutrophil activation, with mitochondrial pathways exerting central control particularly under short-wavelength irradiation. Full article

The cGAS-STING pathway initiates the core cascade of innate immune defense by recognizing pathogen-associated and self-derived abnormal nucleic acids, and key molecules (such as cGAS, STING, downstream IFN-β, IL-6, etc.) may serve as biomarkers in various diseases. The diverse mechanisms by which distinct nucleic acids activate this pathway provide novel insights for therapeutic strategies targeting infectious diseases, cancer, and autoimmune disorders. To prevent aberrant cGAS-STING pathway activation, cells employ multiple regulatory mechanisms, including restricting self-DNA recognition and terminating downstream signaling. Strategies to mitigate pathological activation involve reducing nucleic acid accumulation through nuclease degradation (e.g., of mitochondrial DNA or neutrophil extracellular traps, NETs) or directly inhibiting cGAS or STING. This review elucidates the molecular mechanism of nucleic acid-mediated regulation of cGAS-STING and its role in disease regulation. Full article

Alpha-1 antitrypsin deficiency (AATD) represents a paradigmatic genetic disorder with well-characterized hepatic manifestations but relatively underexplored pulmonary implications. While liver involvement has been extensively reviewed, the underlying mechanisms of lung disease progression remain poorly understood, particularly regarding immunological pathways and inflammatory processes. The pathophysiology involves defective alpha-1 antitrypsin (AAT) production, including AAT variants that induce neutrophil elastase activity, causing progressive alveolar destruction and sustained inflammation, leading to emphysema, as one of the main components of chronic obstructive pulmonary disease (COPD). AATD and smoking represent major risk factors for COPD, the third leading cause of death worldwide at present. In AATD patients, neutrophils, which constitute the majority of circulating leukocytes, become dysregulated. Under normal conditions, cells perform essential functions, including phagocytosis and neutrophil extracellular trap formation (NETosis); in AATD, however, they accumulate excessively in alveolar spaces due to impaired elastase control. The accumulation of Z-AAT polymers within epithelial cells creates a pathological cycle, acting as chemoattractants that sustain pro-inflammatory responses and contribute to chronic obstructive pulmonary disease development. In addition, monocytes, representing a smaller fraction of leukocytes, migrate to inflammatory sites and differentiate into macrophages while secreting AAT with anti-inflammatory properties. However, in PiZZ patients, this protective mechanism fails, as polymer accumulation within cells reduces both AAT secretion and the number of protective human leukocyte antigen(HLA)-DR-monocyte subsets. In particular, macrophages demonstrate remarkable plasticity, switching between pro-inflammatory M1 (classically activated macrophages) and tissue-repairing M2 (alternatively activated macrophages) phenotypes based on environmental cues. In AATD, this adaptive capability becomes compromised due to intracellular polymer accumulation, leading to impaired phagocytic function and dysregulated cytokine production and ultimately perpetuating chronic inflammation and progressive tissue damage. Recent advances in induced pluripotent stem cell (iPSC) technology have facilitated alveolar epithelial cell (AEC) generation, in addition to the correction of AATD mutations through gene editing systems. Despite the limitations of AAT correction, iPSC-derived organoid models harboring AATD mutations can deliver important insights into disease pathophysiology, while gene editing approaches help demonstrate causality between specific mutations and observed phenotypes. Therefore, in this review, we investigated recent studies that can serve as tools for gene editing and drug development based on recently developed iPSC-related technologies to understand the pathogenesis of AATD. Full article