Deoxyribonuclease 1 Q222R single nucleotide polymorphism and long-term mortality after acute myocardial infarction

Leveraging circulating DNase I activity to detect silent coronary artery disease among hypertensive diabetes individuals

In individuals with diabetic hypertension, silent coronary artery disease (CAD) is common due to underlying chronic inflammation, but there is no biomarker to monitor this high-risk group of individuals before noticeable symptoms emerge clinically. cfDNA from dying endothelial cells triggers chronic inflammation, leading us to hypothesize that enzymes that degrade cfDNA, DNase I and/or II, could serve as more sensitive biomarkers for silent CAD. To test this, we conducted a study with 30 hypertensive diabetic patients with clinical symptoms of CAD (CAD-HTN-DM) and 30 controls without CAD (HTN-DM). Negligible serum DNase II activity was detected in both groups. Student's t test was used to compare cfDNA, DNase I activity, and groups. We observed elevated serum DNase I activity in the CAD-HTN-DM group (1.71 ± 0.1 U/mL) compared with the HTN-DM group (1.12 ± 0.1 U/mL) (P < 0.0001). Among the CAD-HTN-DM group, DNase I activity was significantly higher in patients with all three coronary arteries blocked, even though the cfDNA levels were similar in both groups. Elevated DNase I activity was associated with a 1.5-fold increased risk of major adverse cardiac events despite ongoing treatment with statins, antihypertensive medications, and antidiabetic therapies. Surprisingly, serum DNase I activity was lower in patients who suffered a myocardial infarction. By leveraging our observations, we hope that regular monitoring of serum DNase I activity will identify individuals at high risk for the clinical onset of CAD, enabling early intervention to mitigate its adverse effects and slow its progression.NEW & NOTEWORTHY Our observation suggests that the progression of cardiac disease among hypertensive patients with diabetes is associated with elevated DNase I activity that maintains optimal cfDNA levels, thereby reducing its inflammatory potential and worsening of cardiac dysfunction. Thus, DNase I activity may be both a protective factor early on and a potential biomarker for cardiac health among hypertensive patients with diabetes.

Malondialdehyde-specific natural IgM inhibit NETosis triggered by culprit site-derived extracellular vesicles from myocardial infarction patients

BACKGROUND AND AIMS

Neutrophil extracellular traps (NETs) trigger atherothrombosis during acute myocardial infarction (AMI), but mechanisms of induction remain unclear. Levels of extracellular vesicles (EV) carrying oxidation-specific epitopes (OSE), which are targeted by specific natural immunoglobulin M (IgM), are increased at the culprit site in AMI. This study investigated EV as inducers of NETosis and assessed the inhibitory effect of natural anti-OSE-IgM in this process.

METHODS

Blood from the culprit and peripheral site of ST-segment elevation myocardial infarction (STEMI) patients (n = 28) was collected, and myocardial function assessed by cardiac magnetic resonance imaging (cMRI) 4 ± 2 days and 195 ± 15 days post-AMI. Extracellular vesicles were isolated from patient plasma and cell culture supernatants for neutrophil stimulation in vitro and in vivo, in the presence of a malondialdehyde (MDA)-specific IgM or an isotype control. NETosis and neutrophil functions were assessed via enzyme-linked immunosorbent assay and fluorescence microscopy. Pharmacological inhibitors were used to map signalling pathways. Neutrophil extracellular trap markers and anti-OSE-IgM were measured by ELISA.

RESULTS

CD45+ MDA+ EV and NET markers were elevated at the culprit site. Extracellular vesicles induced neutrophil activation and NET formation via TLR4 and PAD4, and mice injected with EV showed increased NETosis. Malondialdehyde-specific IgM levels were inversely associated with citH3 in STEMI patient blood. An MDA-specific IgM inhibited EV-induced NET release in vitro and in vivo. CD45+ MDA+ EV concentrations inversely correlated with left ventricular ejection fraction post-AMI.

CONCLUSIONS

Culprit site-derived EV induce NETosis, while MDA-specific natural IgM inhibit this effect, potentially impacting outcome after AMI.

Nucleic acid liquid biopsies in cardiovascular disease: Cell-free DNA liquid biopsies in cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of death worldwide, and despite treatment efforts, cardiovascular function cannot always be restored, and progression of disease be prevented. Critical insights are oftentimes based on tissue samples. Current knowledge of tissue pathology typically relies on invasive biopsies or postmortem samples. Liquid biopsies, which assess circulating mediators to deduce the histology and pathology of distant tissues, have been advancing rapidly in cancer research and offer a promising approach to be translated to the understanding and treatment of CVD. The widely understood elevations in cell-free DNA during acute and chronic cardiovascular conditions, associate with disease, severity, and offer prognostic value. The role of neutrophil extracellular traps (NETs) and circulating nucleases in thrombosis provide a solid rationale for liquid biopsies in CVD. cfDNA originates from various tissue types and cellular sources, including mitochondria and nuclei, and can be used to trace cell and tissue type lineage, as well as to gain insight into the activation status of cells. This article discusses the origin, structure, and potential utility of cfDNA, offering a deeper and less invasive approach for the understanding of the complexities of CVD.

Neutrophil extracellular traps as a unique target in the treatment of inflammatory pain

Pain is a widespread motivation for seeking healthcare and stands as a substantial global public health concern. Despite comprehensive investigations into the mechanisms of pain sensitization induced by inflammation, efficacious treatments options remain scarce. Neutrophil extracellular traps (NETs) have been associated with the progression and tissue damage of diverse inflammatory diseases. This study aims to explore the impact of NETs on the progression of inflammatory pain and explore potential therapeutic approaches. Initially, we observed neutrophil infiltration and the formation of NETs in the left hind paw of mice with inflammatory pain induced by complete Freund's adjuvant (CFA). Furthermore, we employed the peptidyl arginine deiminase 4 (PAD4) inhibitor Cl-amidine (diluted at 50 mg/kg in saline, administered via tail vein injection once daily for three days) to impede NETs formation and administered DNase1 (diluted at 10 mg/kg in saline, once daily for three days) to break down NETs. We investigated the pathological importance of peripheral NETs formation in inflammatory pain and its influence on the activation of spinal dorsal horn microglia. The findings indicate that neutrophils infiltrating locally generate NETs, leading to an increased release of inflammatory mediators that worsen peripheral inflammatory reactions. Consequently, this results in the transmission of more harmful peripheral stimuli to the spinal cord, triggering microglial activation and NF-κB phosphorylation, thereby escalating neuroinflammation and fostering pain sensitization. Suppression of peripheral NETs can mitigate peripheral inflammation in mice with inflammatory pain, reverse mechanical and thermal hypersensitivity by suppressing microglial activation in the spinal cord, ultimately diminishing inflammatory pain. In conclusion, these discoveries propose that obstructing or intervening with NETs introduces a novel therapeutic avenue for addressing inflammatory pain.

Effect of a 12-Week Walking Program Monitored by Global Physical Capacity Score (GPCS) on Circulating Cell-Free mtDNA and DNase Activity in Patients with Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) involves low-grade mucosal inflammation. Among the various approaches capable of managing the symptoms, physical activity is still under investigation. Despite its benefits, it promotes oxidative stress and inflammation. Mitochondria impacts gut disorders by releasing damage-associated molecular patterns, such as cell-free mtDNA (cf-mtDNA), which support inflammation. This study evaluated the effects of a 12-week walking program on the cf-mtDNA and DNase in 26 IBS and 17 non-IBS subjects. Pro- and anti-inflammatory cytokines were evaluated by ELISA. Digital droplet PCR was used to quantify cf-mtDNA; DNase activity was assessed using a single radial enzyme diffusion assay. PCR-RFLP was used to genotype DNASE1 rs1053874 SNP. Significantly lower IL-10 levels were found in IBS than in non-IBS individuals. Exercise reduced cf-mtDNA in non-IBS subjects but not in IBS patients. DNase activity did not correlate with the cf-mtDNA levels in IBS patients post-exercise, indicating imbalanced cf-mtDNA clearance. Different rs1053874 SNP frequencies were not found between groups. The study confirms the positive effects of regular moderate-intensity physical activity in healthy subjects and its role in cf-mtDNA release and clearance. Walking alone might not sufficiently reduce subclinical inflammation in IBS, based on imbalanced pro- and anti-inflammatory molecules. Prolonged programs are necessary to investigate their effects on inflammatory markers in IBS.

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.

Physical Exercise Promotes DNase Activity Enhancing the Capacity to Degrade Neutrophil Extracellular Traps

(1) Background: An unhealthy lifestyle is a significant contributor to the development of chronic diseases. Physical activity can benefit primary and secondary prevention. Higher DNase activity is associated with favourable outcomes after cardiovascular (CV) events. In this study, we aimed to investigate the influence of consequent endurance exercise on DNase activity. (2) Methods: 98 subjects with at least one CV risk factor but the physical ability to perform endurance training were included. Individuals performed a bicycle stress test at the beginning and after 8 months to assess physical performance. In between, all participants were instructed to engage in guideline-directed physical activity. Blood samples were drawn in two-month intervals to assess routine laboratory parameters, cell-free DNA (cfDNA), and DNase activity. (3) Results: Prevailing CV risk factors were overweight (65.9%), a positive family history (44.9%), hypertension (32.7%) and smoking (20.4%). Performance changed by 7.8 ± 9.1% after 8 months. Comparison of baseline to 8 months revealed a decrease in cfDNA and an increase in DNase activity. This effect was driven by participants who achieved a performance gain. (4) Conclusions: Regular physical activity might improve CV health by increasing DNase activity and thereby, the capacity to lower pro-inflammatory signalling, complementing measures of primary and secondary prevention.

Extracellular traps and the role in thrombosis

Thrombotic complications pose serious health risks worldwide. A significant change in our understanding of the pathophysiology of thrombosis has occurred since the discovery of extracellular traps (ETs) and their prothrombotic properties. As a result of immune cells decondensing chromatin into extracellular fibers, ETs promote thrombus formation by acting as a scaffold that activates platelets and coagulates them. The involvement of ETs in thrombosis has been reported in various thrombotic conditions including deep vein thrombosis (DVT), pulmonary emboli, acute myocardial infarction, aucte ischemic stroke, and abdominal aortic aneurysms. This review summarizes the existing evidence of ETs in human and animal model thrombi. The authors described studies showing the existence of ETs in venous or arterial thrombi. In addition, we studied potential novel therapeutic opportunities related to the resolution or prevention of thrombosis by targeting ETs.

Neutrophil extracellular traps regulate ischemic stroke brain injury

Ischemic stroke prompts a strong inflammatory response, which is associated with exacerbated outcomes. In this study, we investigated mechanistic regulators of neutrophil extracellular trap (NET) formation in stroke and whether they contribute to stroke outcomes. NET-forming neutrophils were found throughout brain tissue of ischemic stroke patients, and elevated plasma NET biomarkers correlated with worse stroke outcomes. Additionally, we observed increased plasma and platelet surface-expressed high-mobility group box 1 (HMGB1) in stroke patients. Mechanistically, platelets were identified as the critical source of HMGB1 that caused NETs in the acute phase of stroke. Depletion of platelets or platelet-specific knockout of HMGB1 significantly reduced plasma HMGB1 and NET levels after stroke, and greatly improved stroke outcomes. We subsequently investigated the therapeutic potential of neonatal NET-inhibitory factor (nNIF) in stroke. Mice treated with nNIF had smaller brain infarcts, improved long-term neurological and motor function, and enhanced survival after stroke. nNIF specifically blocked NET formation without affecting neutrophil recruitment after stroke. Importantly, nNIF also improved stroke outcomes in diabetic and aged mice and was still effective when given 1 hour after stroke onset. These results support a pathological role for NETs in ischemic stroke and warrant further investigation of nNIF for stroke therapy.

The Emerging Role of Neutrophil Extracellular Traps in Arterial, Venous and Cancer-Associated Thrombosis

Neutrophils play a vital role in the formation of arterial, venous and cancer-related thrombosis. Recent studies have shown that in a process known as NETosis, neutrophils release proteins and enzymes complexed to DNA fibers, collectively called neutrophil extracellular traps (NETs). Although NETs were originally described as a way for the host to capture and kill bacteria, current knowledge indicates that NETs also play an important role in thrombosis. According to recent studies, the destruction of vascular microenvironmental homeostasis and excessive NET formation lead to pathological thrombosis. In vitro experiments have found that NETs provide skeletal support for platelets, red blood cells and procoagulant molecules to promote thrombosis. The protein components contained in NETs activate the endogenous coagulation pathway to promote thrombosis. Therefore, NETs play an important role in the formation of arterial thrombosis, venous thrombosis and cancer-related thrombosis. This review will systematically summarize and explain the study of NETs in thrombosis in animal models and in vivo experiments to provide new targets for thrombosis prevention and treatment.