Simvastatin Reduces NETosis to Attenuate Severe Asthma by Inhibiting PAD4 Expression

The methyl-CpG binding domain 2 regulates peptidylarginine deiminase 4 expression and promotes neutrophil extracellular trap formation via the Janus kinase 2 signaling pathway in experimental severe asthma

OBJECTIVE

The prognosis for severe asthma is poor, and the current treatment options are limited. The methyl-CpG binding domain protein 2 (MBD2) participates in neutrophil-mediated severe asthma through epigenetic regulation. Neutrophil extracellular traps (NETs) play a critical role in the pathogenesis of severe asthma. This study aims to detect if MBD2 can reduce NETs formation and the potential mechanism in severe asthma.

METHODS

A severe asthma model was established in C57BL/6 wild-type mice exposure to house dust mite (HDM), ovalbumin (OVA), and lipopolysaccharide (LPS). Enzyme-linked immunosorbent assay was used to measure the concentrations of IL-4, IL-17A, and IFN-γ in lung tissues. Flow cytometry was employed to determine the percentages of Th2, Th17, and Treg cells in lung tissues. Quantitative real-time polymerase chain reaction was utilized to assess the mRNA expression levels of MBD2, JAK2, and PAD4. Western blotting and immunofluorescence were conducted to detect the protein of MBD2, JAK2, PAD4, and CitH3. HL-60 cells were differentiated into neutrophil-like cells by culturing in a medium containing dimethyl sulfoxide and then stimulated with LPS. KCC-07, Ruxolitinib, and Cl-amidine were used to inhibit the expressions of MBD2, JAK2, and PAD4, respectively.

RESULTS

Severe asthma mice were characterized by pulmonary neutrophilic inflammation and increased formation of neutrophil extracellular traps (NETs). The expression of MBD2, JAK2, and PAD4 was elevated in severe asthma mice. Inhibiting the expression of MBD2, JAK2, and PAD4 reduced NETs formation and decreased airway inflammation scores, total cell counts and neutrophil counts in BALF, and percentage of Th2 and Th17 cell in lung tissues, whereas increasing Treg cell counts. In both severe asthma mice and HL-60-differentiated neutrophil-like cells in vitro, inhibiting MBD2 reduced the mRNA and protein expression of JAK2 and PAD4, and inhibiting JAK2 reduced the expression of PAD4 mRNA and protein.

CONCLUSION

MBD2 regulates PAD4 expression through the JAK2 signaling pathway to promote NETs formation in mice with severe asthma. Further bench-based and bedside-based studies targeting the MBD2, PAD4, and JAK2 signaling pathways will help open new avenues for drug development of severe asthma.

Neutrophil percentage-to-albumin ratio (NPAR) as a biomarker for asthma: a cross-sectional analysis of NHANES data

OBJECTIVE

This study aimed to access the neutrophil percentage-to-albumin ratio (NPAR) as a potential biomarker for asthma risk and to explore its association with asthma incidence in a nationally representative adult population.

METHODS

We analyzed cross-sectional data from 17,800 adults in the National Health and Nutrition Examination Survey (NHANES 2009-2018). NPAR was calculated as the ratio of neutrophil percentage to serum albumin concentration. Multivariable logistic regression models adjusted for demographic, socioeconomic, clinical, and laboratory covariates were employed to assess NPAR-asthma associations. Missing data were addressed via multiple imputations, and model performance was evaluated using receiver operating characteristic (ROC) curves with bootstrap validation. Restricted cubic splines analyzed non-linear relationships, while subgroup analyses tested effect heterogeneity across demographic and clinical strata. Sensitivity analyses compared complete-case and imputed datasets.

RESULTS

Elevated NPAR levels were strongly associated with increased asthma risk. In fully adjusted models, each one-unit increase in NPAR corresponded to a 2.6% rise in asthma prevalence (adjusted OR = 1.026, 95% CI: 1.008-1.045, P = 0.0046). ROC curve analysis demonstrated an AUC of 0.699 for NPAR in predicting asthma. Subgroup analyses revealed effect modification by sex, race, and cardiovascular disease history, though interaction terms did not meet Bonferroni-adjusted significance thresholds. Restricted cubic spline analyses indicated a U-shaped dose-response relationship, with minimal risk observed at NPAR values of 12-15, suggesting dual pathological mechanisms: oxidative stress susceptibility at lower NPAR values and neutrophilic inflammation dominance at higher values.

CONCLUSION

This study provides the first epidemiological evidence supporting NPAR as an independent biomarker for asthma risk. The U-shaped association highlights the complex interplay between systemic inflammation and oxidative stress in asthma pathogenesis. While NPAR offers a cost-effective and accessible tool for risk stratification, its moderate predictive performance underscores the need for complementary biomarkers to enhance clinical utility. Future research should integrate serial NPAR measurements and multi-omics profiling to validate its role in asthma management.

Simvastatin mitigates ventilator-induced lung injury in mice with acute respiratory distress syndrome via a mechanism partly dependent on neutrophil extracellular traps

BACKGROUND

Mechanical ventilation (MV) is an essential life support for patients with acute respiratory distress syndrome (ARDS). However, mechanical ventilation in patients with ARDS can cause ventilator-induced lung injury (VILI). Simvastatin can alleviate acute lung injury by anti-inflammatory and enhancing endothelial barrier. The present study aimed to evaluate whether simvastatin could attenuate VILI in mice with ARDS.

METHODS

Mice were randomized into six groups: the sham (S), LPS (L), MV (V), LPS/MV (LV), LPS/MV/simvastatin (MS) and LPS/MV/GSK484 (MG) groups. The mice in the L group received LPS but not ventilation, the mice in the V group received only MV, and the mice in the LV, MS and MG groups received LPS and MV. Additionally, MS group were treated with simvastatin, MG group were treated with GSK484, and the other mice were injected with saline, starting three days prior to mechanical ventilation. The PaO2/FiO2 ratio and wet‒dry weight ratio were calculated. Histopathological changes were observed, and injury scores were calculated. Inflammatory factor levels in the bronchoalveolar lavage fluid (BALF) were detected. Peptidylarginine deiminase 4 (PAD4), neutrophil elastase (NE) and citrullinated histone 3 (Cit-H3) in the lung tissue were detected, apoptosis were also evaluated.

RESULTS

All indices were improved in group S compared with the other groups. The lung injury score and wet‒dry weight ratio were lower, the PaO2/FiO2 ratio was greater, inflammatory factor levels in the BALF were lower, PAD4, NE, and Cit-H3 expression was lower, and apoptosis was decreased in the MS and MG groups compared with the LV group.

CONCLUSIONS

Simvastatin attenuated VILI in mice with ARDS, potentially via reductions in neutrophil extracellular traps (NETs) generation and apoptosis.

Research trends on neutrophil extracellular traps in ischemic stroke: a scientific metrology study

Background

Ischemic stroke (IS) remains a leading global cause of mortality and chronic disability. Neutrophil extracellular traps (NETs), recently identified as neutrophil-derived structures that trap and neutralize pathogens, have increasingly drawn attention for their involvement in IS pathogenesis. Despite a surge in related research, no bibliometric analyses have yet examined the knowledge framework and trends within this emerging field. Here, we conducted a systematic bibliometric analysis to map the research landscape and identify current and potential hotspots regarding NETs in IS.

Methods

Relevant literature published between 2014 and 2024 was systematically retrieved from the Web of Science Core Collection (WoSCC) database. Multiple analytical tools, including CiteSpace, VOSviewer, R package "bibliometrix," and Python scripts, were employed to explore publication trends, academic collaborations, prominent research themes, and emerging topics.

Results

Ninety-two publications were eligible for bibliometric assessment, supplemented by an additional latent Dirichlet allocation (LDA)-based topic analysis of 4,504 documents. China (30 publications) and the United States (23 publications) emerged as leading countries in terms of research output, with global collaboration networks predominantly centering around the United States. Noteworthy contributions also arose from European institutions, particularly Katholieke Universiteit Leuven and Karolinska Institutet. The leading authors identified were Desilles, Jean-Philippe, Ho-Tin-Noé, Benoit, and Mazighi, Mikael. Journals such as Stroke, Annals of Neurology, and Nature Communications significantly influenced this domain. Three main research hotspots emerged: (1) "promoting effect of protein arginine deiminase 4 (PAD4) in NET formation," (2) "cell-free DNA as a biomarker for disease diagnosis," and (3) "influence of platelets and thrombosis on NETs-related diseases."

Conclusion

Our study offers an extensive overview of existing literature and evolving research trajectories concerning NETs in IS, providing researchers with clear insights into current trends and future investigative directions. Nevertheless, our study has limitations-including dependence on a single database (WoSCC), restriction to English-language publications, and inherent constraints of the LDA methodology-that merit consideration in interpreting these findings.

Extracellular Traps in Inflammation: Pathways and Therapeutic Targets

New roles for immune cells, overcoming the classical cytotoxic response, have been highlighted by growing evidence. The immune cells, such as neutrophils, monocytes/macrophages, and eosinophils, are versatile cells involved in the release of web-like DNA structures called extracellular traps (ETs) which represent a relevant mechanism by which these cells prevent microbes' dissemination. In this process, many enzymes, such as elastase, myeloperoxidase (MPO), and microbicidal nuclear and granule proteins, which contribute to the clearance of entrapped microorganisms after DNA binding, are involved. However, an overproduction and release of ETs can cause unwanted and dangerous effects in the host, resulting in several pathological manifestations, among which are chronic inflammatory disorders, autoimmune diseases, cancer, and diabetes. In this review, we discuss the release mechanisms and the double-edged sword role of ETs both in physiological and in pathological contexts. In addition, we evaluated some possible strategies to target ETs aimed at either preventing their formation or degrading existing ones.

Paeonol inhibits NETs-mediated foam cell inflammation through the CitH3/NLRP3/caspase-1 signaling pathway in atherosclerosis

Atherosclerosis is a chronic inflammatory disease characterized by lipid streaks, which are produced by aggregates of lipid-rich foam cells. Foam cells intensify atherosclerosis by secreting a range of inflammatory mediators. Neutrophil extracellular traps produced by activated neutrophils, which are abundantly present in lipid-accumulating plaques. However, the relationship between neutrophil extracellular traps and foam cells inflammation is still unclear. Paeonol is well known for its anti-inflammatory effects in atherosclerosis. Nevertheless, the exact pharmacological mechanisms by which paeonol affects atherosclerosis are not fully understood which require further investigation. The purpose of this study is to investigate the effects of paeonol on the neutrophil extracellular traps' formation and foam cell inflammation caused by neutrophil extracellular traps, and to explore the potential mechanisms. A high-fat diet was administered to ApoE-/- mice for a period of 12 weeks to induce an atherosclerosis model. Our findings demonstrated that paeonol notably suppressed the advancement of atherosclerosis in ApoE-/- mice, curtailed the formation of neutrophil extracellular traps, and lowered inflammatory factor levels within the plaque. In vitro studies have shown that neutrophil extracellular traps could enhance the inflammation in foam cells. CitH3 played a role in the cellular communication between neutrophil extracellular traps and foam cells. Concurrently, NLRP3 acted as a key receptor in the inflammation mediated by this interaction. Paeonol is capable of regulating NE, thereby affecting the formation of neutrophil extracellular traps. Most notably, the foam cell inflammation caused by neutrophil extracellular traps was significantly mitigated by the inclusion of paeonol. Our findings suggested that paeonol inhibited foam cell inflammation which induced by neutrophil extracellular traps through the CitH3/NLRP3/caspase-1 signaling pathway, shedding new lights on its anti-atherosclerotic pharmacological mechanism.

Rosuvastatin accelerates the healing process of partial-thickness burn wounds in rats by reducing TNF-α levels

Introduction

Burn wound healing is a complex, dynamic process that involves a coordinated cascade of cellular responses and phases. Inflammation, proliferation and remodeling are the main phases of tissue repair, while tumor necrosis factor α (TNF-α) and procalcitonin (PCT) seem to be important mediators affecting the inflammatory state. Our aim was to assess the effect of rosuvastatin on tissue repair after partial thickness burn injury in healthy animals.

Material and methods

In this randomized prospective experimental study, 36 male rats were randomly divided into two groups: placebo-treated (PG) and topical rosuvastatin-treated (SG). Under anesthesia, a partial-thickness burn trauma was induced in the dorsal region of the rats using an iron seal. Tissue samples were collected for histopathological examination as well.

Results

Variables of TNF-α, procalcitonin and macroscopic assessment were normally distributed between the two groups on all studied days. The expression of TNF-α was found to be lower in burn injuries treated with topical rosuvastatin in comparison with placebo-treated animals on days 3, 6 and 9. PCT values in rosuvastatin-treated subgroups were statistically significantly lower than in placebo subgroups. Upon macroscopic examination, a significantly smaller burnt area in the statin-treated group was detected compared to the non-statin group on all days, except for day 3. Histopathological examination demonstrated higher levels of mean neutrophil infiltration in the placebo group (day 3). Finally, fibroblast proliferation, angiogenesis and re-epithelization levels were noted to be higher after the topical application of rosuvastatin.

Conclusions

Rosuvastatin accelerated wound healing and down-regulated TNF-α and PCT levels.

Exploration of novel human neutrophil elastase inhibitors from natural compounds: Virtual screening, in vitro, molecular dynamics simulation and in vivo study

BACKGROUND

Human neutrophil elastase (HNE) is an important contributor to lung diseases such as acute lung injury (ALI) or acute respiratory distress syndrome. Therefore, this study aimed to identify natural HNE inhibitors with anti-inflammatory activity through machine learning algorithms, in vitro assays, molecular dynamic simulation, and an in vivo ALI assay.

METHODS

Based on the optimized Discovery Studio two-dimensional molecular descriptors, combined with different molecular fingerprints, six machine learning models were established using the Naïve Bayesian (NB) method to identify HNE inhibitors. Subsequently, the optimal model was utilized to screen 6925 drug-like compounds obtained from the Traditional Chinese Medicine Systems Pharmacy Database and Analysis Platform (TCMSP), followed by ADMET analysis. Finally, 10 compounds with reported anti-inflammatory activity were selected to determine their inhibitory activities against HNE in vitro, and the compounds with the best activity were selected for a 100 ns molecular dynamics simulation and its anti-inflammatory effect was evaluated using Poly (I:C)-induced ALI model.

RESULTS

The evaluation of the in vitro HNE inhibition efficiency of the 10 selected compounds showed that the flavonoid tricetin had the strongest inhibitory effect on HNE. The molecular dynamics simulation indicated that the binding of tricetin to HNE was relatively stable throughout the simulation. Importantly, in vivo experiments indicated that tricetin treatment substantially improved the Poly (I:C)-induced ALI.

CONCLUSION

The proposed NB model was proved valuable for exploring novel HNE inhibitors, and natural tricetin was screened out as a novel HNE inhibitor, which was confirmed by in vitro and in vivo assays for its inhibitory activities.

TNF inhibitors target a mevalonate metabolite/TRPM2/calcium signaling axis in neutrophils to dampen vasculitis in Behçet's disease

TNF inhibitors have been used to treat autoimmune and autoinflammatory diseases. Here we report an unexpected mechanism underlying the therapeutic effects of TNF inhibitors in Behçet's disease (BD), an autoimmune inflammatory disorder. Using serum metabolomics and peripheral immunocyte transcriptomics, we find that polymorphonuclear neutrophil (PMN) from patients with BD (BD-PMN) has dysregulated mevalonate pathway and subsequently increased farnesyl pyrophosphate (FPP) levels. Mechanistically, FPP induces TRPM2-calcium signaling for neutrophil extracellular trap (NET) and proinflammatory cytokine productions, leading to vascular endothelial inflammation and damage. TNF, but not IL-1β, IL-6, IL-18, or IFN-γ, upregulates TRPM2 expression on BD-PMN, while TNF inhibitors have opposite effects. Results from mice with PMN-specific FPP synthetase or TRPM2 deficiency show reduced experimental vasculitis. Meanwhile, analyses of public datasets correlate increased TRPM2 expressions with the clinical benefits of TNF inhibitors. Our results thus implicate FPP-TRPM2-TNF/NETs feedback loops for inflammation aggravation, and novel insights for TNF inhibitor therapies on BD.

Phenotypes and functions of "aged" neutrophils in cardiovascular diseases

Neutrophils are important effector cells of innate immunity and undergo several phenotypic changes after release from the bone marrow. Neutrophils with a late life cycle phenotype are often referred to as "aged" neutrophils. These neutrophils undergo functional changes that accompany stimuli of inflammation, tissue senescence and injury, inducing their maturation and senescence in the circulation and locally in damaged tissues, forming a unique late-life neutrophil phenotype. "Aged" neutrophils, although attenuated in antibacterial capacity, are more active in aging and age-related diseases, exhibit high levels of mitochondrial ROS and mitochondrial DNA leakage, promote senescence of neighboring cells, and exacerbate cardiac and vascular tissue damage, including vascular inflammation, myocardial infarction, atherosclerosis, stroke, abdominal aortic aneurysm, and SARS-CoV-2 myocarditis. In this review, we outline the phenotypic changes of "aged" neutrophils characterized by CXCR4high/CD62Llow, investigate the mechanisms driving neutrophil aging and functional transformation, and analyze the damage caused by "aged" neutrophils to various types of heart and blood vessels. Tissue injury and senescence promote neutrophil infiltration and induce neutrophil aging both in the circulation and locally in damaged tissues, resulting in an "aged" neutrophil phenotype characterized by CXCR4high/CD62Llow. We also discuss the effects of certain agents, such as neutralizing mitochondrial ROS, scavenging IsoLGs, blocking VDAC oligomers and mPTP channel activity, activating Nrf2 activity, and inhibiting neutrophil PAD4 activity, to inhibit neutrophil NET formation and ameliorate age-associated cardiovascular disease, providing a new perspective for anti-aging therapy in cardiovascular disease.

Neutrophil and neutrophil extracellular trap involvement in neutrophilic asthma: A review

Asthma is a highly prevalent chronic inflammatory disease characterized by variable airflow obstruction and airway hyperresponsiveness. Neutrophilic asthma (NA) is classified as "type 2 low" asthma, defined as 65% or more neutrophils in the total cell count. There is no clear consensus on the pathogenesis of NA, and the accumulation of neutrophils and release of neutrophil extracellular traps (NETs) may be responsible for its development. A NET is a large extracellular meshwork comprising cell membrane and granule proteins. It is a powerful antimicrobial defence system that traps, neutralizes, and kills bacteria, fungi, viruses, and parasites and prevents the spread of microorganisms. However, dysregulation of NETs may lead to chronic airway inflammation, is associated with worsening of asthma, and has been the subject of major research advances in chronic lung diseases in recent years. NA is insensitive to steroids, and there is a need to find effective biomarkers as targets for the treatment of NA to replace steroids. This review analyses the mechanisms of action between asthmatic neutrophil recruitment and NET formation and their impact on NA development. It also discusses their possible therapeutic significance in NA, summarizing the advances made in NA agents and providing strategies for the treatment of NA, provide a theoretical basis for the development of new therapeutic drugs, thereby improving the level of diagnosis and treatment, and promoting the research progress in the field of asthma.

Neutrophil PAD4 Expression and Its Pivotal Role in Assessment of Alcohol-Related Liver Disease

Neutrophils release neutrophil extracellular traps (NETs) as a defense strategy in response to broad-spectrum infections and sterile triggers. NETs consist of a DNA scaffold decorated with antimicrobial peptides (AMPs) and enzymatically active proteases, including peptidyl arginine deiminase type 4 (PAD4). Susceptibility to infections and inflammatory dysregulation are hallmarks of alcohol-related liver disease (ALD). Sixty-two patients with ALD were prospectively recruited, and they were followed for 90 days. Twenty-four healthy volunteers served as the control group. PAD4 concentrations were quantified using immunoenzymatic ELISAs. Correlation coefficients between PAD4 blood concentrations and markers of systemic inflammation; liver dysfunction severity scores; and ALD complications were calculated. The receiver operating curves (ROCs) and their areas under the curve (AUCs) were checked in order to assess the accuracy of PAD4 expression in predicting the degree of liver failure and the development of ALD complications. Systemic concentrations of PAD4 were significantly increased in the patients with ALD in comparison with controls. PAD4 levels correlated with the standard markers of inflammation and revealed a good predictive AUC (0.76) for survival in the whole ALD group. PAD4 seems to be an inflammatory mediator and may be potentially applied as a predictor of patient survival in ALD.

Triple threat: neutrophil ER stress, NETosis, airway inflammation escalation

This report aims to propose the novel term 'neutrophil endoplasmic reticulum (ER) stress' (NERS). NERS explores the influence of neutrophil extracellular trap (NET) formation and exacerbation of respiratory ailments. This inquiry aims to advance comprehension in neutrophil biology and respiratory health.

Association between lipid-lowering drugs and allergic diseases: A Mendelian randomization study

Background

Several observational studies suggest a possible link between lipid-lowering drugs and allergic diseases. However, inferring causality from these studies can be challenging due to issues such as bias, reverse causation, and residual confounding. To investigate the potential causal effect of lipid-lowering drugs, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) inhibitors, on allergic diseases (allergic asthma, allergic conjunctivitis, atopic dermatitis, allergic rhinitis, and allergic urticaria), we performed a Mendelian randomization (MR)-based study.

Methods

We employed MR and summary-data-based MR (SMR), analyzing genome-wide association study (GWAS) data from people of European descent. Single nucleotide polymorphisms (SNPs) were employed as instrumental variables. We selected 2 types of genetic measures to represent the impact of lipid-lowering drugs, including genetic variants near or within drug target genes correlated with low-density lipoprotein cholesterol (LDL-C), and expression quantitative trait loci of drug target genes. The inverse-variance weighted (IVW)-MR approach was the primary utilized MR method, while sensitivity analyses were used to test the robustness of the results. We used SMR analysis as a supplementary analytical method, applying the heterogeneity in dependent instruments (HEIDI) test to assess if the observed correlation between gene expression and outcome was due to a linkage situation.

Results

The IVW-MR analysis revealed significant evidence for an association between PCSK9-mediated LDL-C reduction and a decrease in the risk of allergic asthma (odds ratio [OR] = 1.31, 95% confidence interval [CI] = 1.11-1.56; P < 0.01). Likewise, SMR analysis discovered an augmented expression of PCSK9 being linked with a heightened susceptibility to allergic asthma (OR = 1.21, 95% CI = 1.03-1.43; P = 0.02). No consistent evidence was found for other associations in either analysis.

Conclusion

Our findings support a potential causal relationship between PCSK9 activity and an increased risk of allergic asthma. Thus, PCSK9 inhibitors, which reduce PCSK9 activity, might be considered a priority in future clinical trials investigating drugs for allergic asthma prevention or treatment.

Neutrophil Extracellular Traps in Tumors and Potential Use of Traditional Herbal Medicine Formulations for Its Regulation

Neutrophil extracellular traps (NETs) are extracellular fibers composed of deoxyribonucleic acid (DNA) and decorated proteins produced by neutrophils. Recently, NETs have been associated with the development of many diseases, including tumors. Herein, we reviewed the correlation between NETs and tumors. In addition, we detailed active compounds from traditional herbal medicine formulations that inhibit NETs, related nanodrug delivery systems, and antibodies that serve as "guiding moieties" to ensure targeted delivery to NETs. Furthermore, we discussed the strategies used by pathogenic microorganisms to evade NETs.

Top Five Stories of the Cellular Landscape and Therapies of Atherosclerosis: Current Knowledge and Future Perspectives

Atherosclerosis (AS) is characterized by impairment and apoptosis of endothelial cells, continuous systemic and focal inflammation and dysfunction of vascular smooth muscle cells, which is documented as the traditional cellular paradigm. However, the mechanisms appear much more complicated than we thought since a bulk of studies on efferocytosis, transdifferentiation and novel cell death forms such as ferroptosis, pyroptosis, and extracellular trap were reported. Discovery of novel pathological cellular landscapes provides a large number of therapeutic targets. On the other side, the unsatisfactory therapeutic effects of current treatment with lipid-lowering drugs as the cornerstone also restricts the efforts to reduce global AS burden. Stem cell- or nanoparticle-based strategies spurred a lot of attention due to the attractive therapeutic effects and minimized adverse effects. Given the complexity of pathological changes of AS, attempts to develop an almighty medicine based on single mechanisms could be theoretically challenging. In this review, the top stories in the cellular landscapes during the initiation and progression of AS and the therapies were summarized in an integrated perspective to facilitate efforts to develop a multi-targets strategy and fill the gap between mechanism research and clinical translation. The future challenges and improvements were also discussed.

Neutrophil extracellular traps and their implications in airway inflammatory diseases

Neutrophil extracellular traps (NETs) are essential for immune defense and have been increasingly recognized for their role in infection and inflammation. In the context of airway inflammatory diseases, there is growing evidence suggesting the involvement and significance of NETs. This review aims to provide an overview of the formation mechanisms and components of NETs and their impact on various airway inflammatory diseases, including acute lung injury/ARDS, asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis. By understanding the role of NETs in airway inflammation, we can gain valuable insights into the underlying pathogenesis of these diseases and identify potential targets for future therapeutic strategies that either target NETs formation or modulate their harmful effects. Further research is warranted to elucidate the complex interactions between NETs and airway inflammation and to develop targeted therapies that can effectively mitigate their detrimental effects while preserving their beneficial functions in host defense.

Predicting the risk of acute respiratory failure among asthma patients-the A2-BEST2 risk score: a retrospective study

Objectives

Acute respiratory failure (ARF) is a common complication of bronchial asthma (BA). ARF onset increases the risk of patient death. This study aims to develop a predictive model for ARF in BA patients during hospitalization.

Methods

This was a retrospective cohort study carried out at two large tertiary hospitals. Three models were developed using three different ways: (1) the statistics-driven model, (2) the clinical knowledge-driven model, and (3) the decision tree model. The simplest and most efficient model was obtained by comparing their predictive power, stability, and practicability.

Results

This study included 398 patients, with 298 constituting the modeling group and 100 constituting the validation group. Models A, B, and C yielded seven, seven, and eleven predictors, respectively. Finally, we chose the clinical knowledge-driven model, whose C-statistics and Brier scores were 0.862 (0.820-0.904) and 0.1320, respectively. The Hosmer-Lemeshow test revealed that this model had good calibration. The clinical knowledge-driven model demonstrated satisfactory C-statistics during external and internal validation, with values of 0.890 (0.815-0.965) and 0.854 (0.820-0.900), respectively. A risk score for ARF incidence was created: The A2-BEST2 Risk Score (A2 (area of pulmonary infection, albumin), BMI, Economic condition, Smoking, and T2(hormone initiation Time and long-term regular medication Treatment)). ARF incidence increased gradually from 1.37% (The A2-BEST2 Risk Score ≤ 4) to 90.32% (A2-BEST2 Risk Score ≥ 11.5).

Conclusion

We constructed a predictive model of seven predictors to predict ARF in BA patients. This predictor's model is simple, practical, and supported by existing clinical knowledge.

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.

Exosomal PGE2 from M2 macrophages inhibits neutrophil recruitment and NET formation through lipid mediator class switching in sepsis

BACKGROUND

Excess polymorphonuclear neutrophil (PMN) recruitment or excessive neutrophil extracellular trap (NET) formation can lead to the development of multiple organ dysfunction during sepsis. M2 macrophage-derived exosomes (M2-Exos) have exhibited anti-inflammatory activities in some inflammatory diseases to mediate organ functional protection, but their role in treating sepsis-related acute lung injury (ALI) remains unclear. In this study, we sought to investigate whether M2-Exos could prevent potentially deleterious inflammatory effects during sepsis-related ALI by modulating abnormal PMN behaviours.

METHODS

C57BL/6 wild-type mice were subjected to a caecal ligation and puncture (CLP) mouse model to mimic sepsis in vivo, and M2-Exos were administered intraperitoneally 1 h after CLP. H&E staining, immunofluorescence and immunohistochemistry were conducted to investigate lung tissue injury, PMN infiltration and NET formation in the lung. We further demonstrated the role of M2-Exos on PMN function and explored the potential mechanisms through an in vitro coculture experiment using PMNs isolated from both healthy volunteers and septic patients.

RESULTS

Here, we report that M2-Exos inhibited PMN migration and NET formation, alleviated lung injury and reduced mortality in a sepsis mouse model. In vitro, M2-Exos significantly decreased PMN migration and NET formation capacity, leading to lipid mediator class switching from proinflammatory leukotriene B4 (LTB4) to anti-inflammatory lipoxin A4 (LXA4) by upregulating 15-lipoxygenase (15-LO) expression in PMNs. Treatment with LXA4 receptor antagonist attenuated the effect of M2-Exos on PMNs and lung injury. Mechanistically, prostaglandin E2 (PGE2) enriched in M2-Exos was necessary to increase 15-LO expression in PMNs by functioning on the EP4 receptor, upregulate LXA4 production to downregulate chemokine (C-X-C motif) receptor 2 (CXCR2) and reactive oxygen species (ROS) expressions, and finally inhibit PMN function.

CONCLUSIONS

Our findings reveal a previously unknown role of M2-Exos in regulating PMN migration and NET formation through lipid mediator class switching, thus highlighting the potential application of M2-Exos in controlling PMN-mediated tissue injury in patients with sepsis.

Bergapten ameliorates combined allergic rhinitis and asthma syndrome after PM2.5 exposure by balancing Treg/Th17 expression and suppressing STAT3 and MAPK activation in a mouse model

Combined allergic rhinitis and asthma syndrome (CARAS) causes chronic respiratory inflammation in allergic individuals. Long-term exposure to particulate matter 2.5 (PM2.5; particles 2.5 µm or less in diameter) can aggravate respiratory damage. Bergapten (5-methoxysporalen) is a furocoumarin mostly found in bergamot essential oil and has significant antioxidant, anticancer, and anti-inflammatory activity. This study created a model in which CARAS was exacerbated by PM2.5 exposure, in BALB/c mice and explored the potential of bergapten as a therapeutic agent. The bergapten medication increased ovalbumin (OVA)-specific immunoglobulin (Ig) G2a level in serum and decreased OVA-specific IgE and IgG1 expression. Clinical nasal symptoms diminished significantly, with weakened inflammatory reaction in both the nasal mucosa and lungs. Furthermore, bergapten controlled the T helper (Th)1 to Th2 ratio by increasing cytokines associated with Th1-like interleukin (IL)-12 and interferon gamma and decreasing the Th2 cytokines IL-4, IL-5, and IL-13. Factors closely related to the balance between regulatory T cells and Th17 (such as IL-10, IL-17, Forkhead box protein P3, and retinoic-related orphan receptor gamma) were also regulated. Notably, pro-inflammatory cytokines IL-6, IL-1β, and tumor necrosis factor-alpha were reduced by bergapten, which suppressed the activation of both the signal transducer and activator of transcription 3 signaling pathway and the mitogen-activated protein kinase signaling pathway. Therefore, bergapten might have potential as a therapeutic agent for CARAS.