Predictors of neutrophil extracellular traps markers in type 2 diabetes mellitus: associations with a prothrombotic state and hypofibrinolysis

Distinct Roles of Common Genetic Variants and Their Contributions to Diabetes: MODY and Uncontrolled T2DM

Type 2 diabetes mellitus (T2DM) encompasses a range of clinical manifestations, with uncontrolled diabetes leading to progressive or irreversible damage to various organs. Numerous genes associated with monogenic diabetes, exhibiting classical patterns of inheritance (autosomal dominant or recessive), have been identified. Additionally, genes involved in complex diabetes, which interact with environmental factors to trigger the disease, have also been discovered. These genetic findings have raised hopes that genetic testing could enhance diagnostics, disease surveillance, treatment selection, and family counseling. However, the accurate interpretation of genetic data remains a significant challenge, as variants may not always be definitively classified as either benign or pathogenic. Research to date, however, indicates that periodic reevaluation of genetic variants in diabetes has led to more consistent findings, with biases being steadily eliminated. This has improved the interpretation of variants across diverse ethnicities. Clinical studies suggest that genetic risk information may motivate patients to adopt behaviors that promote the prevention or management of T2DM. Given that the clinical features of certain monogenic diabetes types overlap with T2DM, and considering the significant role of genetic variants in diabetes, healthcare providers caring for prediabetic patients should consider genetic testing as part of the diagnostic process. This review summarizes current knowledge of the most common genetic variants associated with T2DM, explores novel therapeutic targets, and discusses recent advancements in the pharmaceutical management of uncontrolled T2DM.

Development and validation of a risk prediction model for 30-day readmission in elderly type 2 diabetes patients complicated with heart failure: a multicenter, retrospective study

Background

Elderly type 2 diabetes mellitus (T2DM) patients complicated with heart failure (HF) exhibit a high rate of 30-day readmission. Predictive models have been suggested as tools for identifying high-risk patients. Thus, we aimed to develop and validate a predictive model using multicenter electronic medical records (EMRs) data to estimate the risk of 30-day readmission in elderly T2DM patients complicated with HF.

Methods

EMRs data of elderly T2DM patients complicated with HF from five tertiary hospitals, spanning 2012 to 2023, were utilized to develop and validate the 30-day readmission model. The model were evaluated using holdout data with the area under the receiver operating characteristic curve (AUROC), calibration curves, decision curve analysis (DCA), and clinical impact curves (CIC).

Results

A total of 1899 patients were included, with 955, 409, and 535 in the derivation, internal validation, and external validation cohorts, respectively. Pulmonary infections (odds ratio [OR]: 3.816, 95% confidence interval [CI]: 2.377-6.128, P < 0.001), anti-hypertensive drug use (OR: 5.536, 95% CI: 1.658-18.486, P = 0.005), and neutrophil percentage-to-albumin ratio (NPAR) (OR: 1.144, 95% CI: 1.093-1.197, P < 0.001) were independent predictors of 30-day readmission risk. AUROC in the derivation, internal validation, and external validation cohorts were 0.782 (95% CI: 0.737-0.826), 0.746 (95% CI: 0.654-0.838), and 0.753 (95% CI: 0.684-0.813), respectively. The calibration curve, DCA results, and CIC results indicated that the model also possessed good predictive power. Additionally, an operation interface on a web page (https://cqykdxtjt.shinyapps.io/readmission/) was created for clinical practitioners to apply.

Conclusion

A 30-day readmission risk prediction model was developed and externally validated. This model facilitates the targeting of interventions for elderly T2DM patients complicated with HF who are at high risk of an early readmission.

Trapped in the NETs: Multiple Roles of Platelets in the Vascular Complications Associated with Neutrophil Extracellular Traps

Neutrophil extracellular traps (NETs) have received significant attention in recent years for their role in both the immune response and the vascular damage associated with inflammation. Platelets have been described as critical components of NETs since the initial description of this physio-pathological response of neutrophils. Platelets have been shown to play a dual role as responders and also as stimulators of NETs. The direct interaction with DNA leads to the entrapment of platelets into NETs, a phenomenon that significantly contributes to the thrombotic complications of inflammation and neutrophil activation, while the direct and paracrine stimulation of neutrophils by platelets has been shown to initiate the process of NET formation. In this review, we provide a comprehensive description of our current understanding of the molecular mechanisms underlying the entrapping of platelets into NETs and, in parallel, the platelet-driven cellular responses promoting NET formation. We then illustrate established examples of the contribution of NETs to vascular pathologies, describe the important questions that remain to be answered regarding the contribution of platelets to NET formation and NET-dependent cardiovascular complication, and highlight the fundamental steps taken towards the application of our understanding of platelets' contribution to NETs for the development of novel cardiovascular therapies.

The Proteome Content of Blood Clots Observed Under Different Conditions: Successful Role in Predicting Clot Amyloid(ogenicity)

A recent analysis compared the proteome of (i) blood clots seen in two diseases-sepsis and long COVID-when blood was known to have clotted into an amyloid microclot form (as judged by staining with the fluorogenic amyloid stain thioflavin T) with (ii) that of those non-amyloid clots considered to have formed normally. Such fibrinaloid microclots are also relatively resistant to fibrinolysis. The proteins that the amyloid microclots contained differed markedly both from the soluble proteome of typical plasma and that of normal clots, and also between the diseases studied (an acute syndrome in the form of sepsis in an ITU and a chronic disease represented by Long COVID). Many proteins in the amyloid microclots were low in concentration in plasma and were effectively accumulated into the fibres, whereas many other abundant plasma proteins were excluded. The proteins found in the microclots associated with the diseases also tended to be themselves amyloidogenic. We here ask effectively the inverse question. This is: can the clot proteome tell us whether the clots associated with a particular disease contained proteins that are observed uniquely (or are highly over-represented) in known amyloid clots relative to normal clots, and thus were in fact amyloid in nature? The answer is in the affirmative in a variety of major coagulopathies, viz., venous thromboembolism, pulmonary embolism, deep vein thrombosis, various cardiac issues, and ischaemic stroke. Galectin-3-binding protein and thrombospondin-1 seem to be especially widely associated with amyloid-type clots, and the latter has indeed been shown to be incorporated into growing fibrin fibres. These may consequently provide useful biomarkers with a mechanistic basis.

Hyperactivity and Pro-inflammatory Functions of Platelets in Diabetes

Cardiovascular complications claim the lives of up to 70% of patients with diabetes mellitus (DM). The mechanisms increasing cardiovascular risk in DM remain to be fully understood and successfully addressed. Nonetheless, there is increasing evidence in the scientific literature of the participation of platelets in the cardiovascular complications of DM. Multiple reports describe the hyperactivity of platelets in DM and their participation in inflammatory responses. The understanding of the mechanisms underlying the contribution of platelets to cardiovascular pathologies in DM will help the development of targeted therapeutic strategies able to reduce cardiovascular risk in these patients. In this literature review, we summarise our current understanding of the molecular mechanisms leading to the contribution of platelets to cardiovascular risk in DM. Both platelet haemostatic activity leading to thrombus formation and their participation to inflammatory processes are stimulated by the biochemical conditions associated with DM. We also present evidence on how DM affect the efficacy of existing therapeutic treatments for thrombosis and, by converse, how antidiabetic drugs may affect platelet function and the haemostasis/thrombosis balance. Taken together, the growing evidence of the different and unexpected roles of platelets in the progression of DM provides a strong rationale for the design of cardiovascular drugs targeting specifically platelets, their pro-inflammatory activity and their activation mechanisms in this disease. Overall, this article provides an important up-to-date overview of the pathophysiological alterations of platelets in DM, which need to be taken into account for the effective management of cardiovascular health in this disease.

The Evolving Role of Neutrophils and Neutrophil Extracellular Traps (NETs) in Obesity and Related Diseases: Recent Insights and Advances

Obesity is a chronic, multifactorial disease characterized by persistent low-grade tissue and systemic inflammation. Fat accumulation in adipose tissue (AT) leads to stress and dysfunctional adipocytes, along with the infiltration of immune cells, which initiates and sustains inflammation. Neutrophils are the first immune cells to infiltrate AT during high-fat diet (HFD)-induced obesity. Emerging evidence suggests that the formation and release of neutrophil extracellular traps (NETs) play a significant role in the progression of obesity and related diseases. Additionally, obesity is associated with an imbalance in gut microbiota and increased intestinal barrier permeability, resulting in the translocation of live bacteria, bacterial deoxyribonucleic acid (DNA), lipopolysaccharides (LPS), and pro-inflammatory cytokines into the bloodstream and AT, thereby contributing to metabolic inflammation. Recent research has also shown that short-chain fatty acids (SCFAs), produced by gut microbiota, can influence various functions of neutrophils, including their activation, migration, and the generation of inflammatory mediators. This review comprehensively summarizes recent advancements in understanding the role of neutrophils and NET formation in the pathophysiology of obesity and related disorders while also focusing on updated potential therapeutic approaches targeting NETs based on studies conducted in humans and animal models.

Good metabolic control is associated with decreased circulating factor VIIa- antithrombin complexes in type 2 diabetes: a cross-sectional study

BACKGROUND

Diabetes is associated with a prothrombotic state that contributes to cardiovascular (CV) events in type 2 diabetes (T2DM). Activated factor VII (FVIIa)- antithrombin (AT) complexes are indicative of tissue factor (TF) exposure and have been associated with thromboembolic risk in coronary artery disease. To our knowledge there have been no reports on FVIIa-AT complexes in T2DM, therefore we assessed factors that determine FVIIa-AT complexes in this disease and the impact of higher complexes on a prothrombotic state.

METHODS

In 108 T2DM patients (mean age 63.8 years, 52.8% men, median HbA1c of 6.9 [interquartile range 6.1-8.2] %) and 83 age- and sex-matched non-diabetic subjects, we measured FVIIa-AT complexes. Metabolic control of T2DM involved fasting glucose, glycated hemoglobin (HbA1c), albumin/creatinine ratio (ACR), and lipid levels. To characterize a prothrombotic state, we determined thrombin generation parameters, fibrinolysis markers, and plasma fibrin clot properties.

RESULTS

FVII-AT complexes in T2DM patients were similar to controls (73.6 [59.4-91.7] vs. 79.6 [59.2-97.1]pM, respectively, p = 0.30). The T2DM patients with FVIIa-AT in the top vs. the bottom quartile had a larger prevalence of active smoking and insulin use, along with higher fasting glucose (+ 36.4%), HbA1c (+ 27.4%), ACR (+ 72.8%), total cholesterol (+ 34.5%), and LDL-cholesterol (+ 80%). FVIIa-AT complexes showed no associations with in vitro thrombin generation potential, plasma fibrin clot properties, or fibrinolysis variables. On multivariable analysis HbA1c, ACR, and total cholesterol remained independently associated with FVIIa-AT complexes in T2DM.

CONCLUSIONS

This is the first study to show that in T2DM higher FVIIa-AT complexes are associated with markers of dyslipidemia and glycemia control, indicating that TF-induced coagulation activation could be suppressed by achieving treatment targets.

A New Application for Cenicriviroc, a Dual CCR2/CCR5 Antagonist, in the Treatment of Painful Diabetic Neuropathy in a Mouse Model

The ligands of chemokine receptors 2 and 5 (CCR2 and CCR5, respectively) are associated with the pathomechanism of neuropathic pain development, but their role in painful diabetic neuropathy remains unclear. Therefore, the aim of our study was to examine the function of these factors in the hypersensitivity accompanying diabetes. Additionally, we analyzed the analgesic effect of cenicriviroc (CVC), a dual CCR2/CCR5 antagonist, and its influence on the effectiveness of morphine. An increasing number of experimental studies have shown that targeting more than one molecular target is advantageous compared with the coadministration of individual pharmacophores in terms of their analgesic effect. The advantage of using bifunctional compounds is that they gain simultaneous access to two receptors at the same dose, positively affecting their pharmacokinetics and pharmacodynamics and consequently leading to improved analgesia. Experiments were performed on male and female Swiss albino mice with a streptozotocin (STZ, 200 mg/kg, i.p.) model of diabetic neuropathy. We found that the blood glucose level increased, and the mechanical and thermal hypersensitivity developed on the 7th day after STZ administration. In male mice, we observed increased mRNA levels of Ccl2, Ccl5, and Ccl7, while in female mice, we observed additional increases in Ccl8 and Ccl12 levels. We have demonstrated for the first time that a single administration of cenicriviroc relieves pain to a similar extent in male and female mice. Moreover, repeated coadministration of cenicriviroc with morphine delays the development of opioid tolerance, while the best and longest-lasting analgesic effect is achieved by repeated administration of cenicriviroc alone, which reduces pain hypersensitivity in STZ-exposed mice, and unlike morphine, no tolerance to the analgesic effects of CVC is observed until Day 15 of treatment. Based on these results, we suggest that targeting CCR2 and CCR5 with CVC is a potent therapeutic option for novel pain treatments in diabetic neuropathy patients.

Right Lower Pulmonary Vein Thrombi and Right Upper Pulmonary Vein Thrombi Connected on the Anterior Wall of the Left Atrium

The interaction between the right upper pulmonary vein (RUPV) and the right lower pulmonary vein (RLPV) is poorly understood. In this paper, using transesophageal echocardiography (TEE) and 80-slice multidetector computed tomography (80-MDCT), we report that the RUPV thrombi and the RLPV thrombi invade the left atrium (LA) and reach the anterior wall of the LA. To our knowledge, this is the first study to directly show the connection between the RUPV thrombi and the RLPV thrombi on the anterior wall of the LA using TEE and 80-MDCT.

Neutrophil extracellular traps - a potential trigger for the development of thrombocytopenia during extracorporeal membrane oxygenation

Neutrophil extracellular traps (NETs) have recently emerged as a potential link between inflammation, immunity, and thrombosis, as well as other coagulation disorders which present a major challenge in the context of extracorporeal membrane oxygenation (ECMO). By examining blood from ECMO patients for NETs and their precursors and correlating them with clinical and laboratory biomarkers of coagulation and inflammation, this study aims to evaluate the association between the presence of NETs in the bloodstream of ECMO patients and the development of potentially severe coagulation disorders during ECMO therapy. Therefore, blood samples were collected from healthy volunteers (n=13) and patients receiving veno-venous (VV) ECMO therapy (n=10). To identify NETs and their precursors, DNA and myeloperoxidase as well as granulocyte marker CD66b were visualized simultaneously by immunofluorescence staining in serial blood smears. Differentiation of DNA-containing objects and identification of NETs and their precursors was performed semiautomatically by a specific algorithm using the shape and size of DNA staining and the intensity of MPO and CD66b signal. Neutrophil extracellular traps and their precursors could be detected in blood smears from patients requiring VV ECMO. Compared to volunteers, ECMO patients presented significantly higher rates of NETs and NET precursors as well as an increased proportion of neutrophil granulocytes in all detected nucleated cells. A high NET rate prior to the initiation of ECMO therapy was associated with both increased IL-6 and TNF-α levels as an expression of a high cytokine burden. These patients with increased NET release also presented an earlier and significantly more pronounced decrease in platelet counts and ATIII activity following initiation of therapy compared with patients with less elevated NETs. These findings provide further indications for the development of immune-mediated acquired thrombocytopenia in ECMO patients.

Diabetes- versus smoking-related thrombo-inflammation in peripheral artery disease

Peripheral artery disease (PAD) is a major health problem with increased cardiovascular mortality, morbidity and disabling critical limb threatening ischemia (CLTI) and amputation. Diabetes mellitus (DM) and cigarette smoke are the main risk factors for the development of PAD. Although diabetes related PAD shows an accelerated course with worse outcome regarding complications, mortality and amputations compared with non-diabetic patients, current medical treatment does not make this distinction and includes standard antiplatelet and lipid lowering drugs for all patients with PAD. In this review we discuss the pathophysiologic mechanisms of PAD, with focus on differences in thrombo-inflammatory processes between diabetes-related and smoking-related PAD, and hypothesize on possible mechanisms for the progressive course of PAD in DM. Furthermore, we comment on current medical treatment and speculate on alternative medical drug options for patients with PAD and DM.

The Causality between Diabetes and Venous Thromboembolism: A Bidirectional Two-Sample Mendelian Randomization Study

BACKGROUND

 Diabetes was considered as a risk factor for venous thromboembolism (VTE), but conflicting findings have been reported from observational studies. This study aimed at investigating the causal associations of type 1 and type 2 diabetes with VTE, including deep vein thrombosis (DVT) and pulmonary embolism (PE).

METHODS

 We designed a bidirectional two-sample Mendelian randomization (MR) analysis by using summary-level data from large genome-wide association studies performed in European individuals. Inverse variance weighting with multiplicative random effect method was used to obtain the primary causal estimates, and weighted median, weighted mode, and MR egger regression were replenished as sensitivity analyses to test the robustness of the results.

RESULTS

 We found no significant causal effects of type 1 diabetes on VTE (odds ratio [OR]: 0.98, 95% confidence interval [CI]: 0.96-1.00, p = 0.043), DVT (OR: 0.98, 95% CI: 0.95-1.00, p = 0.102), and PE (OR: 0.98, 95% CI: 0.96-1.01, p = 0.160). Similarly, no significant associations of type 2 diabetes with VTE (OR: 0.97, 95% CI: 0.91-1.03, p = 0.291), DVT (OR: 0.96, 95% CI: 0.89-1.03, p = 0.255), and PE (OR: 0.97, 95% CI: 0.90-1.04, p = 0.358) were also observed. Results from multivariable MR analysis were consistent with the findings in univariable analysis. In the other direction, the results showed no significant causal effects of VTE on type 1 and type 2 diabetes.

CONCLUSION

 This MR analysis demonstrated no significant causal associations of type 1 and type 2 diabetes with VTE in both directions, in conflict with previous observational studies reporting positive association, which provided clues for understanding the underlying pathogenesis of diabetes and VTE.

Association between Citrullinated Histone H3 and White Matter Lesions Burden in Patients with Ischemic Stroke

INTRODUCTION

Neutrophil extracellular traps play a role in the pathophysiology of stroke and are associated with severity and mortality. We aimed to investigate whether the citrullinated histone H3 (CitH3), a biomarker for neutrophil extracellular traps formation, is associated with the white matter lesion (WML) burden in ischemic stroke patients.

METHODS

Between September 2021 and April 2022, 322 patients were enrolled in this prospective observational cohort study. Serum CitH3 levels were measured after admission using an enzyme-linked immunosorbent assay. WMLs severity was graded according to the Fazekas scale and conceptually defined as mild (total Fazekas score 0-2) and severe (total Fazekas score 3-6). We used multivariable regression models to determine the relationship between CitH3 concentrations and the severity of WMLs burden.

RESULTS

One-hundred and forty-eight (46.0%) patients were diagnosed with severe WMLs burden after admission. Increased CitH3 levels (first quartile vs. fourth quartile of H3Cit, odds ratio, 3.311, 95% confidence interval, 1.336-8.027; p = 0.011) were independently associated with a greater WML burden in the fully adjusted multivariable model. Similar results were found when the H3Cit was analyzed as a continuous variable. Furthermore, the multiple-adjusted spline regression model showed a linear association between H3Cit levels and severe WMLs (P = 0.001 for linearity).

CONCLUSIONS

In the present study, increased CitH3 levels were positively associated with extensive WMLs in ischemic stroke patients, indicating a role of neutrophil extracellular traps formation in the pathogenesis of WMLs.

Spontaneous Neutrophil Extracellular Traps Release Are Inflammatory Markers Associated with Hyperglycemia and Renal Failure on Diabetic Retinopathy

Diabetic retinopathy (DR) is the major microvascular complication of diabetes and causes vitreous traction and intraretinal hemorrhages leading to retinal detachment and total blindness. The evolution of diabetes is related to exacerbating inflammation caused by hyperglycemia and activation of inflammatory cells. Neutrophils are cells able to release structures of extracellular DNA and proteolytic enzymes called extracellular traps (NETs), which are associated with the persistence of inflammation in chronic pathologies. The purpose of the study was to determine the usefulness of neutrophil traps as indicators of DR progression in patients with type 2 diabetes (T2DM). We performed a case-control study of seventy-four cases classified into five groups (non-proliferative DR, mild, moderate, severe, and proliferative) and fifteen healthy controls. We found correlations between NETs and a diagnostic time of T2DM (r = 0.42; p < 0.0001), fasting glucose (r = 0.29; p < 0.01), glycated hemoglobin (HbA1c) (r = 0.31; p < 0.01), estimated glomerular filtration rate (eGFR) (r = -0.29; p < 0.01), and plasma osmolarity (r = 0.25; p < 0.01). These results suggest that due to NETs being associated with clinical indicators, such as HbA1c and eGFR, and that NETs are also associated with DR, clinical indicators might be explained in part through an NET-mediated inflammation process.

Altered platelet reactivity, coagulation, endothelial and inflammatory markers early after smoking cessation verified with cotinine plasma concentration

BACKGROUND/INTRODUCTION

Cigarette smoking is a potent modifiable risk factor for coronary artery disease (CAD). However, little is known about alterations to prothrombotic state and platelet reactivity early after smoking cessation following percutaneous coronary interventions (PCI).

PURPOSE

We investigated alterations to platelet reactivity, coagulation and markers of platelet, endothelial, inflammatory and coagulation activation in clopidogrel-treated patients with CAD after PCI before and after smoking cessation.

METHODS

Smoking patients aged 18 years or older at least 30 days after PCI were recruited and encouraged to quit the habit. At baseline and at 30 days, we measured platelet reactivity with VerifyNow system, thrombomodulin, P-selectin, platelet factor 4 (CXCL4/PF4), citrullinated histone H3 (H3cit) and cotinine level.

RESULTS

Among 117 patients, 84 patients (72%) at a median age of 60.5 years (40 [interquartile range 30-47] pack-years) completed a 30-day follow-up. At day 30, 30 (35.7%) patients stopped smoking with cotinine level < 50 ng/ml. Baseline characteristics were similar in both groups. In smoking quitters a change in platelet reactivity was larger (Δ platelet reactivity units (PRU) 19 [2, 43] vs. -6 [-32, 37], p = 0.018), along with a change in P-selectin concentration (-11.82 [-23.62, 1.34] vs. 7.19 [-14.24, 17.19] ng/ml, p = 0.005). Positive correlations was noticed between cotinine and both P-selectin ( r = 0.23, p = 0.045) and CXCL4 (r = 0.27, p = 0.02).

CONCLUSION

After smoking cessation in CAD patients following PCI an increase in platelet reactivity and a decrease in P-selectin levels were observed. The risk of thrombotic complications post PCI might be paradoxically enhanced among patients who stopped smoking.

Fibrin clot properties in cardiovascular disease: from basic mechanisms to clinical practice

Fibrinogen conversion into insoluble fibrin and the formation of a stable clot is the final step of the coagulation cascade. Fibrin clot porosity and its susceptibility to plasmin-mediated lysis are the key fibrin measures, describing the properties of clots prepared ex vivo from citrated plasma. Cardiovascular disease (CVD), referring to coronary heart disease, heart failure, stroke, and hypertension, has been shown to be associated with the formation of dense fibrin networks that are relatively resistant to lysis. Denser fibrin mesh characterized acute patients at the onset of myocardial infarction or ischaemic stroke, while hypofibrinolysis has been identified as a persistent fibrin feature in patients following thrombotic events or in those with stable coronary artery disease. Traditional cardiovascular risk factors, such as smoking, diabetes mellitus, hyperlipidaemia, obesity, and hypertension, have also been linked with unfavourably altered fibrin clot properties, while some lifestyle modifications and pharmacological treatment, in particular statins and anticoagulants, may improve fibrin structure and function. Prospective studies have suggested that prothrombotic fibrin clot phenotype can predict cardiovascular events in short- and long-term follow-ups. Mutations and splice variants of the fibrinogen molecule that have been proved to be associated with thrombophilia or increased cardiovascular risk, along with fibrinogen post-translational modifications, prothrombotic state, inflammation, platelet activation, and neutrophil extracellular traps formation, contribute also to prothrombotic fibrin clot phenotype. Moreover, about 500 clot-bound proteins have been identified within plasma fibrin clots, including fibronectin, α2-antiplasmin, factor XIII, complement component C3, and histidine-rich glycoprotein. This review summarizes the current knowledge on the mechanisms underlying unfavourable fibrin clot properties and their implications in CVD and its thrombo-embolic manifestations.

Neutrophil extracellular traps in tumor progression and immunotherapy

Tumor immunity is a growing field of research that involves immune cells within the tumor microenvironment. Neutrophil extracellular traps (NETs) are neutrophil-derived extracellular web-like chromatin structures that are composed of histones and granule proteins. Initially discovered as the predominant host defense against pathogens, NETs have attracted increasing attention due to they have also been tightly associated with tumor. Excessive NET formation has been linked to increased tumor growth, metastasis, and drug resistance. Moreover, through direct and/or indirect effects on immune cells, an abnormal increase in NETs benefits immune exclusion and inhibits T-cell mediated antitumor immune responses. In this review, we summarize the recent but rapid progress in understanding the pivotal roles of NETs in tumor and anti-tumor immunity, highlighting the most relevant challenges in the field. We believe that NETs may be a promising therapeutic target for tumor immunotherapy.

Lower Circulating Cell-Free Mitochondrial DNA Is Associated with Heart Failure in Type 2 Diabetes Mellitus Patients

Cell-free nuclear (cf-nDNA) and mitochondrial (cf-mDNA) DNA are released from damaged cells in type 2 diabetes mellitus (T2DM) patients, contributing to adverse cardiac remodeling, vascular dysfunction, and inflammation. The purpose of this study was to correlate the presence and type of cf-DNAs with HF in T2DM patients. A total of 612 T2DM patients were prescreened by using a local database, and 240 patients (120 non-HF and 120 HF individuals) were ultimately selected. The collection of medical information, including both echocardiography and Doppler imagery, as well as the assessment of biochemistry parameters and the circulating biomarkers, were performed at baseline. The N-terminal brain natriuretic pro-peptide (NT-proBNP) and cf-nDNA/cf-mtDNA levels were measured via an ELISA kit and real-time quantitative PCR tests, respectively. We found that HF patients possessed significantly higher levels of cf-nDNA (9.9 ± 2.5 μmol/L vs. 5.4 ± 2.7 μmol/L; p = 0.04) and lower cf-mtDNA (15.7 ± 3.3 μmol/L vs. 30.4 ± 4.8 μmol/L; p = 0.001) than those without HF. The multivariate log regression showed that the discriminative potency of cf-nDNA >7.6 μmol/L (OR = 1.07; 95% CI = 1.03–1.12; p = 0.01) was higher that the NT-proBNP (odds ratio [OR] = 1.10; 95% confidence interval [CI] = 1.04–1.19; p = 0.001) for HF. In conclusion, we independently established that elevated levels of cf-nDNA, originating from NT-proBNP, were associated with HF in T2DM patients.

Spontaneous NETosis in diabetes: A role of hyperglycemia mediated ROS and autophagy

Type 2-diabetes, particularly poorly controlled diabetes, is a risk factor for several infections such as lower respiratory tract and skin infections. Hyperglycemia, a characteristic downstream effect of poorly controlled diabetes, has been shown to impair the function of immune cells, in particular neutrophils. Several studies have demonstrated that hyperglycemia-mediated priming of NADPH oxidase results in subsequent elevated levels of reactive oxygen species (ROS). In healthy neutrophils, ROS plays an important role in pathogen killing by phagocytosis and by induction of Neutrophil Extracellular Traps (NETs). Given the key role of ROS in autophagy, phagocytosis and NETosis, the relationship between these pathways and the role of diabetes in the modulation of these pathways has not been explored previously. Therefore, our study aimed to understand the relationship between autophagy, phagocytosis and NETosis in diabetes. We hypothesized that hyperglycemia-associated oxidative stress alters the balance between phagocytosis and NETosis by modulating autophagy. Using whole blood samples from individuals with and without type 2-diabetes (in the presence and absence of hyperglycemia), we demonstrated that (i) hyperglycemia results in elevated levels of ROS in neutrophils from those with diabetes, (ii) elevated levels of ROS increase LCIII (a marker for autophagy) and downstream NETosis. (iii) Diabetes was also found to be associated with low levels of phagocytosis and phagocytic killing of S. pneumoniae. (iv) Blocking either NADPH oxidase or cellular pathways upstream of autophagy led to a significant reduction in NETosis. This study is the first to demonstrate the role of ROS in altering NETosis and phagocytosis by modulating autophagy in type 2-diabetes. GRAPHICAL ABSTRACT.

The predictive value of Thromboelastography (TEG) parameters in vascular complications in patients with type 2 diabetes mellitus

AIMS

The purpose of this research was to explore the association of TEG parameters (Reaction time, R; Clot kinetics, K; Alpha angle, α-angle; Maximum amplitude, MA) with vascular complications of type 2 diabetes mellitus (T2DM), and assess whether TEG parameters could predict T2DM patients with vascular complications.

METHODS

A total of 68 healthy controls (HC), 57 T2DM patients without vascular complications (NC), 18 T2DM patients with only microvascular complications (MIC), 196 T2DM patients with only macrovascular complications (MAC), and 94 T2DM patients with both microvascular and macrovascular complications (MIC+MAC) were recruited in this study. Participants' clinical information and TEG parameters were recorded. TEG parameters were analyzed by the Jonckheere-Terpstra trend test, assuming the vascular complication was progressing from HC → NC → MIC → MIC+MAC or HC → NC → MAC → MIC+MAC. Receiver operating characteristic (ROC) was performed to explore the diagnostic accuracy of TEG parameters in T2DM with vascular complications.

RESULTS

Shorter TEGK, higher TEG-α-angle, and higher TEG-MA were found in T2DM patients with both microvascular and macrovascular complications (MIC+MAC) group compared with healthy controls (HC) group and T2DM patients without vascular complications (NC) group (P < 0.05). Trend analysis showed that TEG-R/K decreased, but TEG-α-angle/MA increased gradually as the vascular complication progressed (P < 0.001). With stratification of urine microalbumin/creatinine ratio (UACR), diabetic nephropathy with macroalbuminuria (grade A3) behaves shorter TEGK, higher TEG-α-angle/MA compared with normal to mildly increased albuminuria (grade A1) and microalbuminuria (grade A2) (P < 0.05). ROC curves implied that TEGK, TEG-α-angle, and TEG-MA have moderate diagnostic values in T2DM without vascular complications (K-AUC: 0.780, α-angle-AUC: 0.773, and MA-AUC: 0.740) as well as T2DM with both microvascular and macrovascular complications (K-AUC: 0.778, α-angle-AUC: 0.757, and MA-AUC: 0.800).

CONCLUSION

TEG parameters are associated with the progression of vascular complications in T2DM, and it could be a diagnostic indicator for T2DM without vascular complications or with advanced vascular complications.

The Citrullination-Neutrophil Extracellular Trap Axis in Chronic Diseases

Citrullination of proteins is crucial for the formation of neutrophil extracellular traps (NETs) − strands of nuclear DNA expulsed in the extracellular environment along with antimicrobial proteins in order to halt the spread of pathogens. Paradoxically, NETs may be immunogenic and contribute to inflammation. It is known that for the externalization of DNA, a group of enzymes called peptidyl arginine deiminases (PADs) is required. Current research often looks at citrullination, NET formation, PAD overexpression, and extracellular DNA (ecDNA) accumulation in chronic diseases as separate events. In contrast, we propose that citrullination can be viewed as the primary mechanism of autoimmunity, for instance by the formation of anti-citrullinated protein antibodies (ACPAs) but also as a process contributing to chronic inflammation. Therefore, citrullination could be at the center, connecting and impacting multiple inflammatory diseases in which ACPAs, NETs, or ecDNA have already been documented. In this review, we aimed to highlight the importance of citrullination in the etiopathogenesis of a number of chronic diseases and to explore the diagnostic, prognostic, and therapeutic potential of the citrullination-NET axis.

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.

Role of neutrophils in type 2 diabetes and associated atherosclerosis

The development of cardiovascular diseases associated with Type-2 diabetes remains one of the most challenging public health burdens in the developed world. Early onset of metabolic deficiencies, namely dysregulated glucose homeostasis, peripheral insulin resistance, and impaired insulin production are accompanied by both innate and adaptive immune responses that culminate in a state of chronic, low-grade inflammation. Neutrophils are a critical component of the innate immune system which offer frontline defense against pathogens through a variety of potent effector functions. Recent data indicate an essential role of neutrophils in various disease processes that contribute to the development of Type-2 diabetes and atherosclerosis. In this brief review, we aim to distill the most relevant clinical and pre-clinical literature that investigates the role of neutrophils as an important mediator for the Type-2 diabetes/atherosclerosis connection.

The influence of biological and lifestyle factors on circulating cell-free DNA in blood plasma

Research and clinical use of circulating cell-free DNA (cirDNA) is expanding rapidly; however, there remain large gaps in our understanding of the influence of lifestyle and biological factors on the amount of cirDNA present in blood. Here, we review 66 individual studies of cirDNA levels and lifestyle and biological factors, including exercise (acute and chronic), alcohol consumption, occupational hazard exposure, smoking, body mass index, menstruation, hypertension, circadian rhythm, stress, biological sex and age. Despite technical and methodological inconsistences across studies, we identify acute exercise as a significant influence on cirDNA levels. Given the large increase in cirDNA induced by acute exercise, we recommend that controlling for physical activity prior to blood collection is routinely incorporated into study design when total cirDNA levels are of interest. We also highlight appropriate selection and complete reporting of laboratory protocols as important for improving the reproducibility cirDNA studies and ability to critically evaluate the results.

Hypofibrinolysis in type 2 diabetes and its clinical implications: from mechanisms to pharmacological modulation

A prothrombotic state is a typical feature of type 2 diabetes mellitus (T2DM). Apart from increased platelet reactivity, endothelial dysfunction, hyperfibrinogenemia, and hypofibrinolysis are observed in T2DM. A variety of poorly elucidated mechanisms behind impaired fibrinolysis in this disease have been reported, indicating complex associations between platelet activation, fibrin formation and clot structure, and fibrinolysis inhibitors, in particular, elevated plasminogen antigen inhibitor-1 levels which are closely associated with obesity. Abnormal fibrin clot structure is of paramount importance for relative resistance to plasmin-mediated lysis in T2DM. Enhanced thrombin generation, a proinflammatory state, increased release of neutrophil extracellular traps, elevated complement C3, along with posttranslational modifications of fibrinogen and plasminogen have been regarded to contribute to altered clot structure and impaired fibrinolysis in T2DM. Antidiabetic agents such as metformin and insulin, as well as antithrombotic agents, including anticoagulants, have been reported to improve fibrin properties and accelerate fibrinolysis in T2DM. Notably, recent evidence shows that hypofibrinolysis, assessed in plasma-based assays, has a predictive value in terms of cardiovascular events and cardiovascular mortality in T2DM patients. This review presents the current data on the mechanisms underlying arterial and venous thrombotic complications in T2DM patients, with an emphasis on hypofibrinolysis and its impact on clinical outcomes. We also discuss potential modulators of fibrinolysis in the search for optimal therapy in diabetic patients.

Neutrophil extracellular traps in gastrointestinal cancer

Gastrointestinal (GI) cancer is a high-risk malignancy and is characterized by high mortality and morbidity worldwide. Neutrophil extracellular traps (NETs), a weblike structure consisting of chromatin DNA with interspersed cytoplasmic and granule proteins, are extruded by activated neutrophils to entrap and kill bacteria and fungi. However, accumulating evidence shows that NETs are related to the progression and metastasis of cancer. In clinical studies, NETs infiltrate primary GI cancer tissues and are even more abundant in metastatic lesions. The quantity of NETs in peripheral blood is revealed to be associated with ascending clinical tumour stages, indicating the role of NETs as a prognostic markers in GI cancer. Moreover, several inhibitors of NETs or NET-related proteins have been discovered and used to exert anti-tumour effects in vitro or in vivo, suggesting that NETs can be regarded as targets in the treatment of GI cancer. In this review, we will focus on the role of NETs in gastric cancer and colorectal cancer, generalizing their effects on tumour-related thrombosis, invasion and metastasis. Recent reports are also listed to show the latest evidences of how NETs affect GI cancer. Additionally, notwithstanding the scarcity of systematic studies elucidating the underlying mechanisms of the interaction between NETs and cancer cells, we highlight the potential importance of NETs as biomarkers and anti-tumour therapeutic targets.

Neutrophil Extracellular Trap Formation and Syndecan-1 Shedding Are Increased After Trauma

BACKGROUND

Damage-associated molecular patterns (DAMPs) stimulate endothelial syndecan-1 shedding and neutrophil extracellular traps (NET) formation. The role of NETs in trauma and trauma-induced hypercoagulability is unknown. We hypothesized that trauma patients with accelerated thrombin generation would have increased NETosis and syndecan-1 levels.

METHODS

In this pilot study, we analyzed 50 citrated plasma samples from 30 trauma patients at 0 h (n = 22) and 6 h (n = 28) from time of injury (TOI) and 21 samples from healthy volunteers, for a total of 71 samples included in analysis. Thrombin generation was quantified using calibrated automated thrombogram (CAT) and reported as lag time (LT), peak height (PH), and time to peak (ttPeak). Nucleosome calibrated (H3NUC) and free histone standardized (H3Free) ELISAs were used to quantify NETs. Syndecan-1 levels were quantified by ELISA. Results are presented as median [interquartile range] and Spearman rank correlations.

RESULTS

Plasma levels of H3NUC were increased in trauma patients as compared with healthy volunteers both at 0 h (89.8 ng/mL [35.4, 180.3]; 18.1 ng/mL [7.8, 37.4], P = 0.002) and at 6 h (86.5 ng/mL [19.2, 612.6]; 18.1 ng/mL [7.8, 37.4], P = 0.003) from TOI. H3Free levels were increased in trauma patients at 0 h (5.74 ng/mL [3.19, 8.76]; 1.61 ng/mL [0.66, 3.50], P = 0.002) and 6 h (5.52 ng/mL [1.46, 11.37]; 1.61 ng/mL [0.66, 3.50], P = 0.006). Syndecan-1 levels were greater in trauma patients (4.53 ng/mL [3.28, 6.28]; 2.40 ng/mL [1.66, 3.20], P < 0.001) only at 6 h from TOI. H3Free and syndecan-1 levels positively correlated both at 0 h (0.376, P = 0.013) and 6 h (0.583, P < 0.001) from TOI. H3NUC levels and syndecan-1 levels were positively correlated at 6 h from TOI (0.293, P = 0.041). TtPeak correlated inversely to H3 NUC (-0.358, P = 0.012) and syndecan-1 levels (-0.298, P = 0.038) at 6 h from TOI.

CONCLUSIONS

Our pilot study demonstrates that trauma patients have increased NETosis, measured by H3NUC and H3Free levels, increased syndecan-1 shedding, and accelerated thrombin generation kinetics early after injury.

To Trap a Pathogen: Neutrophil Extracellular Traps and Their Role in Mucosal Epithelial and Skin Diseases

Neutrophils are the most abundant circulating innate immune cells and comprise the first immune defense line, as they are the most rapidly recruited cells at sites of infection or inflammation. Their main microbicidal mechanisms are degranulation, phagocytosis, cytokine secretion and the formation of extracellular traps. Neutrophil extracellular traps (NETs) are a microbicidal mechanism that involves neutrophil death. Since their discovery, in vitro and in vivo neutrophils have been challenged with a range of stimuli capable of inducing or inhibiting NET formation, with the objective to understand its function and regulation in health and disease. These networks composed of DNA and granular components are capable of immobilizing and killing pathogens. They comprise enzymes such as myeloperoxidase, elastase, cathepsin G, acid hydrolases and cationic peptides, all with antimicrobial and antifungal activity. Therefore, the excessive formation of NETs can also lead to tissue damage and promote local and systemic inflammation. Based on this concept, in this review, we focus on the role of NETs in different infectious and inflammatory diseases of the mucosal epithelia and skin.

Effects of Hyperglycemia and Diabetes Mellitus on Coagulation and Hemostasis

In patients with diabetes, metabolic disorders disturb the physiological balance of coagulation and fibrinolysis, leading to a prothrombotic state characterized by platelet hypersensitivity, coagulation disorders and hypofibrinolysis. Hyperglycemia and insulin resistance cause changes in platelet number and activation, as well as qualitative and/or quantitative modifications of coagulatory and fibrinolytic factors, resulting in the formation of fibrinolysis-resistant clots in patients with diabetes. Other coexisting factors like hypoglycemia, obesity and dyslipidemia also contribute to coagulation disorders in patients with diabetes. Management of the prothrombotic state includes antiplatelet and anticoagulation therapies for diabetes patients with either a history of cardiovascular disease or prone to a higher risk of thrombus generation, but current guidelines lack recommendations on the optimal antithrombotic treatment for these patients. Metabolic optimizations like glucose control, lipid-lowering, and weight loss also improve coagulation disorders of diabetes patients. Intriguing, glucose-lowering drugs, especially cardiovascular beneficial agents, such as glucagon-like peptide-1 receptor agonists and sodium glucose co-transporter inhibitors, have been shown to exert direct anticoagulation effects in patients with diabetes. This review focuses on the most recent progress in the development and management of diabetes related prothrombotic state.

Neutrophil extracellular trap-associated molecules: a review on their immunophysiological and inflammatory roles

Neutrophil extracellular traps (NETs) are a defense mechanism against pathogens. They are composed of DNA and various proteins and have the ability to hinder microbial spreading and survival. However, NETs are not only related to infections but also participate in sterile inflammatory events. In addition to DNA, NETs contain histones, serine proteases, cytoskeletal proteins and antimicrobial peptides, all of which have immunomodulatory properties that can augment or decrease the inflammatory response. Extracellular localization of these molecules alerts the immune system of cellular damage, which is triggered by recognition of damage-associated molecular patterns (DAMPs) through specific pattern recognition receptors. However, not all of these molecules are DAMPs and may have other immunophysiological properties in the extracellular space. The release of NETs can lead to production of pro-inflammatory cytokines (due to TLR2/4/9 and inflammasome activation), the destruction of the extracellular matrix, activation of serine proteases and of matrix metallopeptidases (MMPs), modulation of cellular proliferation, induction of cellular migration and adhesion, promotion of thrombogenesis and angiogenesis and disruption of epithelial and endothelial permeability. Understanding the dynamics of NET-associated molecules, either individually or synergically, will help to unravel their role in inflammatory events and open novel perspectives for potential therapeutic targets. We here review molecules contained within NETS and their immunophysiological roles.

Associations of NETs with inflammatory risk and atherosclerotic severity in ST-segment elevation myocardial infarction

AIM

To investigate the association between neutrophil extracellular traps (NETs) in coronary thrombus and risk profile of patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

All participants enrolled in the Optical Coherence Tomography Examination in Acute Myocardial Infarction (NCT03593928) registry from March 2017 to November 2019 were screened and 104 patients were qualified for the current analysis. Coronary aspirated materials were collected and culprit lesion characteristics were examined by optical coherence tomography. NETs in thrombus were identified by immunofluorescence as the co-localization of anti-histone H3 and myeloperoxidase, and NETs level was assessed using a semi-quantitative score. Patient-oriented composite endpoint included all-cause death, myocardial infarction, stroke, any revascularization, and re-admission for heart failure.

RESULTS

According to NETs burden, 44 patients were in the low NETs group and 60 in the high NETs group. The two groups were comparable in age, sex, and comorbidities but the high NETs group presented with significantly higher level of high-sensitivity C reactive protein than the low NETs group (median 9.3 mg/L vs 5.2 mg/L, p = 0.036). Although culprit plaque morphology did not differ between groups, the lipid arc was smaller (maximal lipid arc 320° vs 360°, p = 0.012) and the flow area was larger (median 1.85mm² vs 1.65mm², p = 0.041) in the high NETs group. No significant difference was observed between groups in patient-oriented composite endpoint.

CONCLUSION

Increased NETs in aspirated coronary thrombus appear to be associated with more elevated inflammation but less advanced atherosclerosis.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT03593928.

NETosis as a Pathogenic Factor for Heart Failure

Heart failure threatens the lives of patients and reduces their quality of life. Heart failure, especially heart failure with preserved ejection fraction, is closely related to systemic and local cardiac persistent chronic low-grade aseptic inflammation, microvascular damage characterized by endothelial dysfunction, oxidative stress, myocardial remodeling, and fibrosis. However, the initiation and development of persistent chronic low-grade aseptic inflammation is unexplored. Oxidative stress-mediated neutrophil extracellular traps (NETs) are the main immune defense mechanism against external bacterial infections. Furthermore, NETs play important roles in noninfectious diseases. After the onset of myocardial infarction, atrial fibrillation, or myocarditis, neutrophils infiltrate the damaged tissue and aggravate inflammation. In tissue injury, damage-related molecular patterns (DAMPs) may induce pattern recognition receptors (PRRs) to cause NETs, but whether NETs are directly involved in the pathogenesis and development of heart failure and the mechanism is still unclear. In this review, we analyzed the markers of heart failure and heart failure-related diseases and comorbidities, such as mitochondrial DNA, high mobility box group box 1, fibronectin extra domain A, and galectin-3, to explore their role in inducing NETs and to investigate the mechanism of PRRs, such as Toll-like receptors, receptor for advanced glycation end products, cGAS-STING, and C-X-C motif chemokine receptor 2, in activating NETosis. Furthermore, we discussed oxidative stress, especially the possibility that imbalance of thiol redox and MPO-derived HOCl promotes the production of 2-chlorofatty acid and induces NETosis, and analyzed the possibility of NETs triggering coronary microvascular thrombosis. In some heart diseases, the deletion or blocking of neutrophil-specific myeloperoxidase and peptidylarginine deiminase 4 has shown effectiveness. According to the results of current pharmacological studies, MPO and PAD4 inhibitors are effective at least for myocardial infarction, atherosclerosis, and certain autoimmune diseases, whose deterioration can lead to heart failure. This is essential for understanding NETosis as a therapeutic factor of heart failure and the related new pathophysiology and therapeutics of heart failure.

Diabetes Mellitus/Poststroke Hyperglycemia: a Detrimental Factor for tPA Thrombolytic Stroke Therapy

Intravenous administration of tissue-type plasminogen activator (IV tPA) therapy has long been considered a mainstay in ischemic stroke management. However, patients respond to IV tPA therapy unequally with some subsets of patients having worsened outcomes after treatment. In particular, diabetes mellitus (DM) is recognized as a clinically important vascular comorbidity that leads to lower recanalization rates and increased risks of hemorrhagic transformation (HT). In this short-review, we summarize the recent advances in understanding of the underlying mechanisms involved in post-IV tPA worsening of outcome in diabetic stroke. Potential pathologic factors that are related to the suboptimal tPA recanalization in diabetic stroke include higher plasma plasminogen activator inhibitor (PAI)-1 level, diabetic atherogenic vascular damage, glycation of the tPA receptor annexin A2, and alterations in fibrin clot density. While factors contributing to the exacerbation of HT in diabetic stroke include hyperglycemia, vascular oxidative stress, and inflammation, tPA neurovascular toxicity and imbalance in extracellular proteolysis are discussed. Besides, impaired collaterals in DM also compromise the efficacy of IV tPA therapy. Additionally, several tPA combination approaches developed from experimental studies that may help to optimize IV tPA therapy are also briefly summarized. In summary, more research efforts are needed to improve the safety and efficacy of IV tPA therapy in ischemic stroke patients with DM/poststroke hyperglycemia.

Neutrophil extracellular traps promote scar formation in post-epidural fibrosis

Low back pain following spine surgery is a major complication due to excessive epidural fibrosis, which compresses the lumbar nerve. The mechanisms of epidural fibrosis remain largely elusive. In the drainage samples from patients after spine operation, neutrophil extracellular traps (NETs) and NETs inducer high-mobility group box 1 were significantly increased. In a mouse model of laminectomy, NETs developed in the wound area post epidural operation, accompanied with macrophage infiltration. In vitro, macrophages ingested NETs and thereby increased the elastase from NETs via the receptor for advanced glycation end product. Moreover, NETs boosted the expression of fibronectin in macrophages, which was dependent on elastase and could be partially blocked by DNase. NF-κB p65 and Smad pathways contributed to the increased expression fibronectin in NETs-treated macrophages. In the mouse spine operation model, post-epidural fibrosis was significantly mitigated with the administration of DNase I, which degraded DNA and cleaved NETs. Our study shed light on the roles and mechanisms of NETs in the scar formation post spine operation.

Quantification of citrullinated histones: Development of an improved assay to reliably quantify nucleosomal H3Cit in human plasma

BACKGROUND

Recent data propose a diagnostic and prognostic capacity for citrullinated histone H3 (H3Cit), a marker of neutrophil extracellular traps (NETs), in pathologic conditions such as cancer and thrombosis. However, current research is hampered by lack of standardized assays.

OBJECTIVES

We aimed to develop an assay to reliably quantify nucleosomal H3Cit in human plasma.

METHODS

We assessed the common practice of in vitro enzymatically modified histone H3 as calibration standards and the specificity of available intrapeptidyl citrulline antibodies. Based on our findings, we developed and validated a novel assay to quantify nucleosomal H3Cit in human plasma.

RESULTS

We show that enzymatically citrullinated H3 proteins are compromised by high enzyme-dependent lot variability as well as instability in plasma. We furthermore demonstrate that the majority of commercially available antibodies against intrapeptidyl citrulline display poor specificity for their reported target when tested against a panel of semi-synthetic nucleosomes containing distinct histone H3 citrullinations. Finally, we present a novel assay utilizing highly specific monoclonal antibodies and semi-synthetic nucleosomes containing citrulline in place of arginine at histone H3, arginine residues 2, 8, and 17 (H3R2,8,17Cit) as calibration standards. Rigorous validation of this assay shows its capacity to accurately and reliably quantify nucleosomal H3Cit levels in human plasma with clear elevations in cancer patients compared to healthy individuals.

CONCLUSIONS

Our novel approach using defined nucleosome controls enables reliable quantification of H3Cit in human plasma. This assay will be broadly applicable to study the role of histone citrullination in disease and its utility as a biomarker.

Pulmonary Neutrophilic Inflammation and Noncommunicable Diseases: Pathophysiology, Redox Mechanisms, Biomarkers, and Therapeutics

Significance: Pulmonary neurophilic inflammation (PNI) is the homing and activation of neutrophil with damage to the microvasculature. This process is involved in pulmonary damage in patients exposed to airborne pollutants (exogenous stressors) and also to systemic inflammation/oxidative stress (endogenous stressors) associated with noncommunicable diseases (NCDs). Recent Advances: PNI is an important trigger of the early onset and progression of NCD in susceptible patients exposed to airborne pollutants. Irritation of the lung microvasculature by exogenous and endogenous stressors causes PNI. Circulating endogenous stressors in NCD can cause PNI. Critical Issues: Air pollution-triggered PNI causes increased circulating endogenous stressors that can trigger NCD in susceptible patients. Systemic inflammation/oxidative stress associated with NCD can cause PNI. Inflammation/end-oxidation products of macromolecules are also potential biomarkers and therapeutic targets for NCD-triggered PNI- and PNI-triggered NCD. Future Directions: Understanding the molecular mechanism of PNI triggered by exogenous or endogenous stressors will help explain the early onset of NCD in susceptible patients exposed to air pollution. It can also help undercover biomarkers and mechanism-based therapeutic targets in air pollutant-triggered PNI, PNI-triggered NCD, and NCD-triggered PNI.

Neutrophil Extracellular Traps (NETs) and Damage-Associated Molecular Patterns (DAMPs): Two Potential Targets for COVID-19 Treatment

COVID-19 is a pandemic disease caused by the new coronavirus SARS-CoV-2 that mostly affects the respiratory system. The consequent inflammation is not able to clear viruses. The persistent excessive inflammatory response can build up a clinical picture that is very difficult to manage and potentially fatal. Modulating the immune response plays a key role in fighting the disease. One of the main defence systems is the activation of neutrophils that release neutrophil extracellular traps (NETs) under the stimulus of autophagy. Various molecules can induce NETosis and autophagy; some potent activators are damage-associated molecular patterns (DAMPs) and, in particular, the high-mobility group box 1 (HMGB1). This molecule is released by damaged lung cells and can induce a robust innate immunity response. The increase in HMGB1 and NETosis could lead to sustained inflammation due to SARS-CoV-2 infection. Therefore, blocking these molecules might be useful in COVID-19 treatment and should be further studied in the context of targeted therapy.

Citrullinated histone H3, a marker of extracellular trap formation, is increased in blood of stable asthma patients

BACKGROUND

Emerging data indicates that extracellular traps (ETs), structures formed by various immune cell types, may contribute to the pathology of noninfectious inflammatory diseases. Histone hypercitrullination is an important step in ETs formation and citrullinated histone H3 (H3cit) is considered a novel and specific biomarker of that process. In the present study we have evaluated circulating H3cit in stable asthmatics and investigated its relationship with asthma severity, pulmonary function and selected blood and bronchoalveolar lavage (BAL) biomarkers.

METHODS

In 60 white adult stable asthmatics and 50 well-matched controls we measured serum levels of H3cit. In asthmatics we also performed bronchoscopy with BAL. We analyzed blood and BAL biomarkers, including interleukin (IL)-4, IL-5, IL-6, IL-10, IL-12p70, IL-17A and interferon γ. For statistical analysis, Mann-Whitney U-test, χ2 test, one-way ANCOVA, ROC curve analysis and univariate linear regression were applied. Independent determinants of H3cit were established in a multiple linear regression model.

RESULTS

Asthma was characterized by elevated circulating H3cit (17.49 [11.25-22.58] vs. 13.66 [8.66-18.87] ng/ml, p = 0.03). In asthmatics positive associations were demonstrated between serum H3cit and lung function variables, including total lung capacity (TLC) (β = 0.37 [95% CI 0.24-0.50]) and residual volume (β = 0.38 [95% CI 0.25-0.51]). H3cit was increased in asthma patients receiving systemic steroids (p = 0.02), as well as in subjects with BAL eosinophilia above 144 cells/ml (p = 0.02). In asthmatics, but not in controls, circulating H3cit correlated well with number of neutrophils (β = 0.31 [95% CI 0.19-0.44]) and monocytes (β = 0.42 [95% CI 0.29-0.55]) in peripheral blood. Furthermore, BAL macrophages, BAL neutrophils, TLC, high-sensitivity C-reactive protein, Il-12p70 and bronchial obstruction degree were independent determinants of H3cit in a multivariate linear regression model.

CONCLUSIONS

Asthma is characterized by increased circulating H3cit likely related to the enhanced lung ETs formation. Inhibition of ETs might be a therapeutic option in selected asthma phenotypes, such as neutrophilic asthma.

Mechanistic Causes of Reduced Cardiorespiratory Fitness in Type 2 Diabetes

Type 2 diabetes (T2D) has been rising in prevalence in the United States and worldwide over the past few decades and contributes to significant morbidity and premature mortality, primarily due to cardiovascular disease (CVD). Cardiorespiratory fitness (CRF) is a modifiable cardiovascular (CV) risk factor in the general population and in people with T2D. Young people and adults with T2D have reduced CRF when compared with their peers without T2D who are similarly active and of similar body mass index. Furthermore, the impairment in CRF conferred by T2D is greater in women than in men. Various factors may contribute to this abnormality in people with T2D, including insulin resistance and mitochondrial, vascular, and cardiac dysfunction. As proof of concept that understanding the mediators of impaired CRF in T2D can inform intervention, we previously demonstrated that an insulin sensitizer improved CRF in adults with T2D. This review focuses on how contributing factors influence CRF and why they may be compromised in T2D. Functional exercise capacity is a measure of interrelated systems biology; as such, the contribution of derangement in each of these factors to T2D-mediated impairment in CRF is complex and varied. Therefore, successful approaches to improve CRF in T2D should be multifaceted and individually designed. The current status of this research and future directions are outlined.

Novel biomarkers for the evaluation of aging-induced proteinopathies

Proteinopathies are characterized by aging related accumulation of misfolded protein aggregates. Irreversible covalent modifications of aging proteins may significantly affect the native three dimentional conformation of proteins, alter their function and lead to accumulation of misfolded protein as dysfunctional aggregates. Protein misfolding and accumulation of aberrant proteins are known to be associated with aging-induced proteinopathies such as amyloid ß and tau proteins in Alzheimer's disease, α-synuclein in Parkinson's disease and islet amyloid polypeptides in Type 2 diabetes mellitus. Protein oxidation processes such as S-nitrosylation, dityrosine formation and some of the newly elucidated processes such as carbamylation and citrullination recently drew the attention of researchers in the field of Gerontology. Studying over these processes and illuminating their relations between proteinopathies may help to diagnose early and even to treat age related disorders. Therefore, we have chosen to concentrate on aging-induced proteinopathic nature of these novel protein modifications in this review.

Elevated Lactate Levels in Acute Pulmonary Embolism Are Associated with Prothrombotic Fibrin Clot Properties: Contribution of NETs Formation

BACKGROUND

Elevated plasma lactate levels correlate with high mortality rate in acute pulmonary embolism (PE) patients. We hypothesized that elevated lactate levels correlate with prothrombotic fibrin clot properties and enhanced neutrophil extracellular trap (NET) formation in acute PE.

METHODS

As many as 126 normotensive acute PE patients (aged 58 ± 14 years) were enrolled. Plasma fibrin clot permeability (Ks), clot lysis time (CLT), endogenous thrombin potential (ETP), citrullinated histone H3 (citH3), and plasminogen activator inhibitor-1 antigen (PAI-1), together with plasma L-lactate levels were evaluated on admission.

RESULTS

Lactate levels ≥2 mM were found in 70 (55.6%) patients in whom we observed 29% higher neutrophil count and 45% elevated plasma citH3 levels. Elevated lactate levels were associated with more prothrombotic fibrin properties as reflected by 11% reduced Ks, 13% longer CLT, along with 11% increased ETP. Lactate levels were positively associated with plasma citH3 concentrations, ETP, CLT, and PAI-1 (p < 0.05). An increase of lactate levels by 1 mM leading to the prolongation of CLT by 8.82 minutes was shown in the linear regression.

CONCLUSIONS

Our findings suggest a new mechanism contributing to a negative impact of elevated lactate levels on prognosis in acute PE patients, in particular hypofibrinolysis, associated with enhanced NET formation.

Plasma neutrophil extracellular trap level is modified by disease severity and inhaled corticosteroids in chronic inflammatory lung diseases

A flow cytometry-based method was developed to quantify in vivo circulating neutrophil extracellular trap (NET) levels in plasma and compare them in patients with different chronic inflammatory lung diseases. Seventeen asthmatic and 11 control children, 12 adult controls, 46 asthmatic, 6 COPD and 6 adult patients with asthma-COPD overlap syndrome (ACOS) were recruited in the study. The presence of NETs in unstimulated cell-free plasma was confirmed and visualized by confocal laser-scanning microscopy. No significant differences were found in plasma NET levels between children and adults, children with or without asthma and adults with or without asthma, COPD or ACOS. When asthmatic patients were stratified according to their disease severity the average plasma NET level was significantly higher in asthmatic patients with more serious symptoms (adjusted p = 0.027). Patients with poorer pulmonary functions had higher plasma NET levels which negatively correlated with the FEV1 values (r = -0.39, p = 0.002). Patients who were medicated daily with inhaled corticosteroids (ICS) had significantly lower average plasma NET level than patients who did not or just occasionally used ICS (p = 0.027). If further studies confirm the NET-lowering effect of ICS in the circulation, it can be utilized in diseases where NETosis contributes to the pathogenesis.

Extracellular Trap by Blood Cells: Clinical Implications

BACKGROUND

Extracellular trap formation (ETosis) by various blood cells has been reported. This trap contains DNA, histones and granular proteins which can elicit an innate immune response by entrapping microorganisms. The trap thus formed has been reported to have an involvement in various pathogenic conditions as well. This review focusses on the trap formation by different blood cells, the immune response associated with trap formation and also its role in various clinical conditions.

METHOD

An extensive literature survey on ETosis by blood cells from 2003 to 2019 has been done. After going through the literature throughly, in this review we focuses on the trap formation by different blood cell types such as neutrophils, macrophages, eosinophils, basophils, mast cells, plasmacytoid dentritic cells, and monocytes. The mechanism with which it releases trap, the immune response it elicits and ultimately its involvement in various pathogenic conditions are described here. This article extensively covered all the above aspects and finally comprehends in nutshell the various stimuli that are currently known in trigerring the ETosis, its effect and ultimately its role in disease process.

RESULTS

A clarity about the extracellular trap formation by various blood cells, mechanism of ETosis, role of Etosis in microbial invasion and in various pathogenic situations by various blood cells have been described here.

CONCLUSION

The current understanding about the process of ETosis and its effects has been extensively described here. Along with lot of favourable outcomes, the process of ETosis will lead to lot of pathogenic situations including thrombosis, tumour metastasis and sepsis. Current understanding about ETosis is limited. Indepth understanding of ETosis may have great therapeutic potential in the diagnosis, guiding of therapy and prognostication in various pathogenic situations including infectious conditions, autoimmune disorders and tumors.

Sodium fluoride exposure triggered the formation of neutrophil extracellular traps

In recent years, numerous studies paid more attention to the molecular mechanisms associated with fluoride toxicity. However, the detailed mechanisms of fluoride immunotoxicity in bovine neutrophils remain unclear. Neutrophil extracellular traps (NETs) is a novel immune mechanism of neutrophils. We hypothesized that sodium fluoride (NaF) can trigger NETs activation and release, and investigate the related molecular mechanisms during the process. We exposed peripheral blood neutrophils to 1 mM NaF for 120 min in bovine neutrophils. The results showed that NaF exposure triggered NET-like structures decorated with histones and granule proteins. Quantitative measurement of NETs content correlated positively with the concentration of NaF. Mechanistically, NaF exposure increased reactive oxygen species (ROS) levels and phosphorylation levels of ERK, p38, whereas inhibiting the activities of superoxide dismutase (SOD) and catalase (CAT) compared with control neutrophils. NETs formation is induced by NaF and this effect was inhibited by the inhibitors diphenyleneiodonium chloride (DPI), U0126 and SB202190. Our findings described the potential importance of NaF-triggered NETs related molecules, which might help to extend the current understanding of NaF immunotoxicity.