Neutrophil activation precedes myocardial injury in patients with acute myocardial infarction

Myeloperoxidase as a Promising Therapeutic Target after Myocardial Infarction

Coronary artery disease (CAD) and myocardial infarction (MI) remain leading causes of death and disability worldwide. CAD begins with the formation of atherosclerotic plaques within the intimal layer of the coronary arteries, a process driven by persistent arterial inflammation and oxidation. Myeloperoxidase (MPO), a mammalian haem peroxidase enzyme primarily expressed within neutrophils and monocytes, has been increasingly recognised as a key pro-inflammatory and oxidative enzyme promoting the development of vulnerable coronary atherosclerotic plaques that are prone to rupture, and can precipitate a MI. Mounting evidence also implicates a pathogenic role for MPO in the inflammatory process that follows a MI, which is characterised by the rapid infiltration of activated neutrophils into the damaged myocardium and the release of MPO. Excessive and persistent cardiac inflammation impairs normal cardiac healing post-MI, resulting in adverse cardiac outcomes and poorer long-term cardiac function, and eventually heart failure. This review summarises the evidence for MPO as a significant oxidative enzyme contributing to the inappropriate inflammatory responses driving the progression of CAD and poor cardiac healing after a MI. It also details the proposed mechanisms underlying MPO's pathogenic actions and explores MPO as a novel therapeutic target for the treatment of unstable CAD and cardiac damage post-MI.

Myeloperoxidase induces monocyte migration and activation after acute myocardial infarction

Introduction

Myocardial infarction (MI) is a significant contributor to morbidity and mortality worldwide. Many individuals who survive the acute event continue to experience heart failure (HF), with inflammatory and healing processes post-MI playing a pivotal role. Polymorphonuclear neutrophils (PMN) and monocytes infiltrate the infarcted area, where PMN release high amounts of the heme enzyme myeloperoxidase (MPO). MPO has numerous inflammatory properties and MPO plasma levels are correlated with prognosis and severity of MI. While studies have focused on MPO inhibition and controlling PMN infiltration into the infarcted tissue, less is known on MPO's role in monocyte function.

Methods and results

Here, we combined human data with mouse and cell studies to examine the role of MPO on monocyte activation and migration. We revealed a correlation between plasma MPO levels and monocyte activation in a patient study. Using a mouse model of MI, we demonstrated that MPO deficiency led to an increase in splenic monocytes and a decrease in cardiac monocytes compared to wildtype mice (WT). In vitro studies further showed that MPO induces monocyte migration, with upregulation of the chemokine receptor CCR2 and upregulation of inflammatory pathways identified as underlying mechanisms.

Conclusion

Taken together, we identify MPO as a pro-inflammatory mediator of splenic monocyte recruitment and activation post-MI and provide mechanistic insight for novel therapeutic strategies after ischemic injury.

Neutrophil-Enriched Biomarkers and Long-Term Prognosis in Acute Coronary Syndrome: a Systematic Review and Meta-analysis

Activated neutrophils release a range of inflammatory products that represent potential biomarkers, and there is interest in the prognostic value of these in acute coronary syndrome (ACS) patients. We conducted a systematic review to examine neutrophil-enriched biomarkers and the occurrence of major adverse cardiovascular events (MACE) in patients with ACS. We identified twenty-seven studies including 17,831 patients with ACS. The most studied biomarkers were neutrophil gelatinase-associated lipocalin (NGAL) and myeloperoxidase (MPO). Meta-analyses showed that elevated NGAL was associated with higher MACE rates (unadjusted risk ratio (RR) 1.52, 95% CI 1.12-2.06, p = 0.006) as were elevated MPO levels (unadjusted RR 1.61, 95% CI 1.22-2.13, p = 0.01). There was limited data suggesting that increased levels of calprotectin, proteinase-3 and double-stranded DNA were also associated with MACE. These results suggest that higher levels of neutrophil-enriched biomarkers may be predictive of MACE in patients with ACS, although higher-quality studies are needed to confirm these observations.

Electrochemical detection of myeloperoxidase (MPO) in blood plasma with surface-modified electroless nickel immersion gold (ENIG) printed circuit board (PCB) electrodes

Printed circuit board (PCB) based biosensors have often utilized hard gold electroplating, that nullifies the cost advantages of this technology as compared to screen printed electrodes. Electroless nickel immersion gold (ENIG) is a popular gold deposition process widely used in PCB manufacturing, but vulnerable to pinhole defects and large surface roughness, which compromises biosensor performance. In this work, we present a method to address these challenges through electrodeposition of methylene blue (MB) to cover surface defects and improve electroactivity of ENIG PCB electrodes. We also demonstrate a process to realize in situ synthesis of gold nanoparticles (AuNPs) using acid-functionalized multi-walled carbon nanotubes (MWCNTs) as scaffold, that are used to immobilize antibody for the target molecule (myeloperoxidase: MPO, early warning biomarker for cardiovascular diseases) through a modified cysteamine/gluteraldehyde based process. The processing steps on the electrode surface are developed in a manner that do not compromise the integrity of the electrode, resulting in repeatable and reliable performance of the sensors. Further, we demonstrate a cost-effective microfluidic packaging process to integrate a capillary pump driven microfluidic channel on the PCB electrode for seamless introduction of samples for testing. We demonstrate the ability of the sensor to distinguish clinically abnormal concentrations of MPO from normal concentrations through extensive characterization using spiked serum and blood plasma samples, with a limit of detection of 15.79 ng/mL.

Plasma Concentrations of New Biochemical Markers of Atherosclerosis in Patients with Dyslipidemia-A Pilot Study

Background and Objectives: The process of atherosclerotic plaque formation and its destabilisation is a process in which many proteins and cytokines are involved. Examples of such proteins are osteopontin (OPN), osteoprotegerin (OPG), metalloproteinases (MMPs) and myeloperoxidase (MPO). The aim of our study is to compare the concentrations of the above-mentioned markers in the plasma of patients with the confirmed presence of rupture plaque in comparison with the plasma of healthy people. Materials and Methods: The study included people suffering from dyslipidemia in whom the presence of unstable atherosclerotic plaque was confirmed by ultrasound. The concentrations of OPN, OPG, MPO, metalloproteinase 2 (MMP-2), and metalloproteinase 9 (MMP-9) in the plasma of these people were determined and compared with the concentrations of these proteins in the plasma of healthy people. Results: Levels of MMP-2, MMP-9 (p < 0.001), OPN, and OPG (p < 0.05) were statistically significantly lower in the group of healthy people than in the study group. Differences in MPO concentration were not statistically significant (p = 0.073). Conclusions: In the plasma of people with confirmed presence of rupture plaque, the concentrations of OPN, OPG, and MMPs are higher compared to the group of healthy people, which may suggest the use of these proteins as novel markers of the presence of unstable atherosclerotic plaque.

Macrophages secrete murinoglobulin-1 and galectin-3 to regulate neutrophil degranulation after myocardial infarction

Inflammation presides early after myocardial infarction (MI) as a key event in cardiac wound healing. Ischemic cardiomyocytes secrete inflammatory cues to stimulate infiltration of leukocytes, predominantly macrophages and neutrophils. Infiltrating neutrophils degranulate to release a series of proteases including matrix metalloproteinase (MMP)-9 to break down extracellular matrix and remove necrotic myocytes to create space for the infarct scar to form. While neutrophil to macrophage communication has been explored, the reverse has been understudied. We used a proteomics approach to catalogue the macrophage secretome at MI day 1. Murinoglobulin-1 (MUG1) was the highest-ranked secreted protein (4.1-fold upregulated at MI day 1 vs. day 0 pre-MI cardiac macrophages, p = 0.004). By transcriptomics evaluation, galectin-3 (Lgals3) was 2.2-fold upregulated (p = 0.008) in MI day 1 macrophages. We explored the direct roles of MUG1 and Lgals3 on neutrophil degranulation. MUG1 blunted while Lgals3 amplified neutrophil degranulation in response to phorbol 12-myristate 13-acetate or interleukin-1β, as measured by MMP-9 secretion. Lgals3 itself also stimulated MMP-9 secretion. To determine if MUG1 regulated Lgals3, we co-stimulated neutrophils with MUG1 and Lgals3. MUG1 limited degranulation stimulated by Lgals3 by 64% (p < 0.001). In vivo, MUG1 was elevated in the infarct region at MI days 1 and 3, while Lgals3 increased at MI day 7. The ratio of MUG1 to Lgals3 positively correlated with infarct wall thickness, revealing that MUG1 attenuated infarct wall thinning. In conclusion, macrophages at MI day 1 secrete MUG1 to limit and Lgals3 to accentuate neutrophil degranulation to regulate infarct wall thinning.

Prognostic Role of Neutrophil to High-Density Lipoprotein Cholesterol Ratio for All-Cause and Cardiovascular Mortality in the General Population

Background

Neutrophil counts to high-density lipoprotein cholesterol ratio (NHR), a composite marker of inflammation and lipid metabolism, has been considered as a predictor of clinical outcomes in patients with acute ischemic stroke and acute myocardial infarction. However, the predictive value of NHR for all-cause and cardiovascular mortality in the general population remains unclear.

Methods

Our study population comprised 34,335 adults in the United States obtained from the National Health and Nutrition Examination Survey (NHANES) (1999–2014) and were grouped in accordance with tertiles of NHR. Kaplan–Meier curves and log-rank test were used to investigate the differences of survival among groups. Multivariate Cox regression, restricted cubic spline analysis, and subgroup analysis were applied to explore the relationship of NHR with all-cause and cardiovascular mortality.

Results

The mean age of the study cohort was 49.6 ± 18.2 years and 48.4% were men. During a median follow-up of 82 months, 4,310 (12.6%) all-cause deaths and 754 (2.2%) cardiovascular deaths occurred. In a fully-adjusted Cox regression model, participants in the highest tertile had 29% higher hazard of all-cause mortality than those in the lowest tertile [hazard ratio (HR) = 1.29, 95% CI: 1.19–1.41]. For cardiovascular mortality, the continuously increased HR with 95% CIs among participants in the middle and highest tertile were 1.30 (1.06–1.59) and 1.44 (1.17–1.78), respectively. The restricted cubic spline curve indicated that NHR had a non-linear association with all-cause mortality (p for non-linearity < 0.001) and a linear association with cardiovascular mortality (p for non-linearity = 0.553).

Conclusion

Increased NHR was a strong and independent predictor of all-cause and cardiovascular mortality in the general population.

A Review of Novel Cardiac Biomarkers in Acute or Chronic Cardiovascular Diseases: The Role of Soluble ST2 (sST2), Lipoprotein-Associated Phospholipase A2 (Lp-PLA2), Myeloperoxidase (MPO), and Procalcitonin (PCT)

While the received traditional predictors are still the mainstay in the diagnosis and prognosis of CVD events, increasing studies have focused on exploring the ancillary effect of biomarkers for the aspiring of precision. Under which circumstances, soluble ST2 (sST2), lipoprotein-associated phospholipase A2 (Lp-PLA2), myeloperoxidase (MPO), and procalcitonin (PCT) have recently emerged as promising markers in the field of both acute and chronic cardiovascular diseases. Existent clinical studies have demonstrated the significant associations between these markers with various CVD outcomes, which further verified the potentiality of markers in helping risk stratification and diagnostic and therapeutic work-up of patients. The current review article is aimed at illuminating the applicability of these four novels and often neglected cardiac biomarkers in common clinical scenarios, including acute myocardial infarction, acute heart failure, and chronic heart failure, especially in the emergency department. By thorough classification, combination, and discussion of biomarkers with clinical and instrumental evaluation, we hope the current study can provide insights into biomarkers and draw more attention to their importance.

Serum Progranulin As a Risk Predictor in Patients with Acute Myocardial Infarction

BACKGROUND Although progranulin was recently proposed as an adipokine that may be involved in glucose metabolic and inflammatory diseases, the role of serum progranulin in cardiovascular disease is elusive and remains disputed. The aim of our research was to determine the concentration of serum progranulin in Chinese patients with cardiovascular disease, notably in acute myocardial infarction (AMI), and its relationship to other cardiometabolic risk factors. MATERIAL AND METHODS This prospective observational study included 342 Chinese AMI patients and 255 healthy control subjects. Serum progranulin concentrations and various cardiometabolic risk factor levels were investigated. We assessed the relationship between progranulin and other cardiometabolic risk factors. Logistic regression analysis was applied to evaluate risk factors in patients with AMI. RESULTS Progranulin levels were obviously elevated in AMI patients compared to control subjects (P=0.0001). Correlation analysis showed that progranulin levels were positively associated with coronary artery disease severity (r=0.380, P=0.0001), glucose (r=0.195, P=0.015), and myeloperoxidase (r=0.198, P=0.014). In logistic regression analysis, serum progranulin (Exp(B)=1.104, 95% CI=1.043-1.168, P=0.001), myeloperoxidase (Exp(B)=1.006, 95% CI=1.003-1.008, P=0.0001), and uric acid (Exp(B)=1.020, 95% CI=1.009-1.032, P=0.0001) were independent risk factors in AMI patients. CONCLUSIONS Patients with AMI had significantly higher serum progranulin concentrations than control subjects. This study suggests that serum progranulin is an independent risk predictor in Chinese patients with AMI.

The expression of myeloperoxidase in thrombi is associated with reduced heme oxygenase-1 induction and worse left ventricular remodeling in patients with acute ST-elevation myocardial infarction

Background

Myeloperoxidase (MPO) secreted by neutrophils is the enzyme that kills bacteria and other pathogens. Acute myocardial infarction (AMI) is usually caused by thrombosis in response to vulnerable plaque rupture. Circulating MPO was found to be associated with increased mortality in AMI patients. However, the relationship between MPO in thrombi and the prognosis of AMI patients remains unknown.

Hypothesis

MPO expression in thrombi is associated with the prognosis of patients who underwent primary percutaneous coronary intervention (PCI) after AMI.

Methods

This study included 41 consecutive patients with acute ST‐elevation myocardial infarction, who successfully underwent primary PCI, during which we collected thrombi remaining in the culprit artery using aspiration catheters. These thrombus samples were fixed, and immunohistochemical staining against MPO and heme oxygenase‐1 (HO‐1) was conducted. Enrolled patients were divided into two groups based on the induction of thrombotic MPO, which was quantified using Image J software.

Methods

We observed that increased MPO was associated with lower left ventricular ejection fraction (LVEF) and worse LV remodeling in AMI patients. Instead, patients with decreased thrombotic MPO induction had a considerable improvement in LVEF 1 month after discharge (54.4 ± 2.0% vs. 61.1 ± 2.3%, p < 0.01). In the MPO group, a reduction in the thrombotic HO‐1 level contributed to the development of adverse LV remodeling. Logistic regression showed that MPO was a considerable risk factor for adverse LV remodeling (adjusted OR 3.70, p < 0.05).

Conclusion

MPO expression in thrombi is associated with reduced LVEF and deteriorated LV remodeling in AMI patients, which may be due to HO‐1 suppression in thrombi.

Neutrophils as a Novel Target of Modified Low-Density Lipoproteins and an Accelerator of Cardiovascular Diseases

Neutrophil extracellular traps (NETs) significantly contribute to various pathophysiological conditions, including cardiovascular diseases. NET formation in the vasculature exhibits inflammatory and thrombogenic activities on the endothelium. NETs are induced by various stimulants such as exogenous damage-associated molecular patterns (DAMPs). Oxidatively modified low-density lipoprotein (oxLDL) has been physiologically defined as a subpopulation of LDL that comprises various oxidative modifications in the protein components and oxidized lipids, which could act as DAMPs. oxLDL has been recognized as a crucial initiator and accelerator of atherosclerosis through foam cell formation by macrophages; however, recent studies have demonstrated that oxLDL stimulates neutrophils to induce NET formation and enhance NET-mediated inflammatory responses in vascular endothelial cells, thereby suggesting that oxLDL may be involved in cardiovascular diseases through neutrophil activation. As NETs comprise myeloperoxidase and proteases, they have the potential to mediate oxidative modification of LDL. This review summarizes recent updates on the analysis of NETs, their implications for cardiovascular diseases, and prospects for a possible link between NET formation and oxidative modification of lipoproteins.

Myeloperoxidase: A versatile mediator of endothelial dysfunction and therapeutic target during cardiovascular disease

Myeloperoxidase (MPO) is a prominent mammalian heme peroxidase and a fundamental component of the innate immune response against microbial pathogens. In recent times, MPO has received considerable attention as a key oxidative enzyme capable of impairing the bioactivity of nitric oxide (NO) and promoting endothelial dysfunction; a clinically relevant event that manifests throughout the development of inflammatory cardiovascular disease. Increasing evidence indicates that during cardiovascular disease, MPO is released intravascularly by activated leukocytes resulting in its transport and sequestration within the vascular endothelium. At this site, MPO catalyzes various oxidative reactions that are capable of promoting vascular inflammation and impairing NO bioactivity and endothelial function. In particular, MPO catalyzes the production of the potent oxidant hypochlorous acid (HOCl) and the catalytic consumption of NO via the enzyme's NO oxidase activity. An emerging paradigm is the ability of MPO to also influence endothelial function via non-catalytic, cytokine-like activities. In this review article we discuss the implications of our increasing knowledge of the versatility of MPO's actions as a mediator of cardiovascular disease and endothelial dysfunction for the development of new pharmacological agents capable of effectively combating MPO's pathogenic activities. More specifically, we will (i) discuss the various transport mechanisms by which MPO accumulates into the endothelium of inflamed or diseased arteries, (ii) detail the clinical and basic scientific evidence identifying MPO as a significant cause of endothelial dysfunction and cardiovascular disease, (iii) provide an up-to-date coverage on the different oxidative mechanisms by which MPO can impair endothelial function during cardiovascular disease including an evaluation of the contributions of MPO-catalyzed HOCl production and NO oxidation, and (iv) outline the novel non-enzymatic mechanisms of MPO and their potential contribution to endothelial dysfunction. Finally, we deliver a detailed appraisal of the different pharmacological strategies available for targeting the catalytic and non-catalytic modes-of-action of MPO in order to protect against endothelial dysfunction in cardiovascular disease.

Neutrophil-Mediated Cardiac Damage After Acute Myocardial Infarction: Significance of Defining a New Target Cell Type for Developing Cardioprotective Drugs

Significance: Acute myocardial infarction (AMI) is a leading cause of death worldwide. Post-AMI survival rates have increased with the introduction of angioplasty as a primary coronary intervention. However, reperfusion after angioplasty represents a clinical paradox, restoring blood flow to the ischemic myocardium while simultaneously inducing ion and metabolic imbalances that stimulate immune cell recruitment and activation, mitochondrial dysfunction and damaging oxidant production. Recent Advances: Preclinical data indicate that these metabolic imbalances contribute to subsequent heart failure through sustaining local recruitment of inflammatory leukocytes and oxidative stress, cardiomyocyte death, and coronary microvascular disturbances, which enhance adverse cardiac remodeling. Both left ventricular dysfunction and heart failure are strongly linked to inflammation and immune cell recruitment to the damaged myocardium. Critical Issues: Overall, therapeutic anti-inflammatory and antioxidant agents identified in preclinical trials have failed in clinical trials. Future Directions: The versatile neutrophil-derived heme enzyme, myeloperoxidase (MPO), is gaining attention as an important oxidative mediator of reperfusion injury, vascular dysfunction, adverse ventricular remodeling, and atrial fibrillation. Accordingly, there is interest in therapeutically targeting neutrophils and MPO activity in the setting of heart failure. Herein, we discuss the role of post-AMI inflammation linked to myocardial damage and heart failure, describe previous trials targeting inflammation and oxidative stress post-AMI, highlight the potential adverse impact of neutrophil and MPO, and detail therapeutic options available to target MPO clinically in AMI patients.

Protective effect of puerarin against burn-induced heart injury in rats

The present study evaluated the potential protective effects of puerarin and its associated mechanism on burn-induced myocardial damage. A total of 40 healthy adult Wistar rats were randomly divided into four groups: i) Sham; ii) burn; iii) burn + puerarin; and iv) puerarin. Serum levels of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α) and IL-6 were measured using ELISA. Myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels were determined in myocardial homogenates using a commercial assay kit. TUNEL staining and western blot analysis of cleaved and pro-caspase-3 were also performed to assess apoptosis. Activation of p38-MAPK, ERK, JNK and AKT were measured using western blot analysis. Left ventricular systolic pressure, maximum rates of increase/decrease in left ventricular pressure, creatine kinase MB activity and cardiac troponin T levels were found to be altered in the burn group 12 h after burn, which were reversed by puerarin treatment. Injection of puerarin following burn injury also reduced heart water content. Serum levels of IL-1β, TNF-α and IL-6 were significantly higher in the burn group compared with those in the sham group. Puerarin treatment reduced serum levels of IL-1β, TNF-α and IL-6, in addition to reducing MPO activity and MDA levels in myocardial tissues. Puerarin inhibited the activation of caspase-3, p38, ERK and JNK following severe burn, but elevated Akt activation following severe burn. In conclusion, puerarin improved cardiac function in rats following severe burn injury, which may be due to reduced myocardial injury, inhibition of cardiomyocyte apoptosis and reduced oxidative inflammatory stress; the MAPK and AKT signaling pathways are proposed to the underlying mechanism of these findings.

Neutrophil to high-density lipoprotein ratio has a superior prognostic value in elderly patients with acute myocardial infarction: a comparison study

Background

The importance of the lipid-related biomarkers has been implicated in the pathological process and prognosis of acute myocardial infarction (AMI). Our work was conducted to discuss and compare the predictive ability of the neutrophil to high-density lipoprotein cholesterol (HDL-C) ratio (NHR) with other existing prognostic indices, for instance, the monocyte to HDL-C ratio (MHR) and the low-density lipoprotein cholesterol (LDL-C) to HDL-C ratio (LDL-C/HDL-C) in elderly patients with AMI.

Methods

Our population was 528 consecutive elderly AMI patients (65–85 years) who were enrolled from Tongji Hospital and grouped according to the cutoff points which were depicted by the receiver operating characteristic (ROC). The Kaplan-Meier curves were plotted with the survival data from the follow-up to investigate the difference between cutoff point-determined groups. Moreover, we assessed the impact of NHR, MHR, LDL-C/HDL-C on the long-term mortality and recurrent myocardial infarction (RMI) with Cox proportional hazard models.

Results

Mean duration of follow-up was 673.85 ± 14.32 days (median 679.50 days). According to ROC curve analysis, NHR ≥ 5.74, MHR ≥ 0.67, LDL-C/HDL-C ≥ 3.57 were regarded as high-risk groups. Kaplan-Meier analysis resulted that the high-NHR, high-MHR and high-LDL-C/HDL-C groups presented higher mortality and RMI rate than the corresponding low-risk groups in predicting the long-term clinical outcomes (log-rank test: all P < 0.050). In multivariate analysis, compared with MHR and LDL-C/HDL-C, only NHR was still recognized as a latent predictor for long-term mortality (harzard ratio [HR]: 1.96, 95% confidence interval [CI]: 1.02 to 3.75, P = 0.044) and long-term RMI (HR: 2.23, 95% CI: 1.04 to 4.79, P = 0.040). Furthermore, the positive correlation between NHR and Gensini score (r = 0.15, P < 0.001) indicated that NHR was relevant to the severity of coronary artery to some extent.

Conclusions

NHR, a novel laboratory marker, might be a predictor of the long-term clinical outcomes of elderly patients with AMI, which was superior to MHR and LDL-C/HDL-C.

Binding of myeloperoxidase to the extracellular matrix of smooth muscle cells and subsequent matrix modification

The extracellular matrix (ECM) of tissues is susceptible to modification by inflammation-associated oxidants. Considerable data support a role for hypochlorous acid (HOCl), generated by the leukocyte-derived heme-protein myeloperoxidase (MPO) in these changes. HOCl can modify isolated ECM proteins and cell-derived matrix, with this resulting in decreased cell adhesion, modulated proliferation and gene expression, and phenotypic changes. Whether this arises from free HOCl, or via site-specific reactions is unresolved. Here we examine the mechanisms of MPO-mediated changes to human coronary smooth muscle cell ECM. MPO is shown to co-localize with matrix fibronectin as detected by confocal microscopy, and bound active MPO can initiate ECM modification, as detected by decreased antibody recognition of fibronectin, versican and type IV collagen, and formation of protein carbonyls and HOCl-mediated damage. These changes are recapitulated by a glucose/glucose oxidase/MPO system where low continuous fluxes of H₂O₂ are generated. HOCl-induced modifications enhance MPO binding to ECM proteins as detected by ELISA and MPO activity measurements. These data demonstrate that MPO-generated HOCl induces ECM modification by interacting with ECM proteins in a site-specific manner, and generates alterations that increase MPO adhesion. This is proposed to give rise to an increasing cycle of alterations that contribute to tissue damage.

Sodium tanshinone IIA sulfonate prevents the adverse left ventricular remodelling: Focus on polymorphonuclear neutrophil-derived granule components

AIMS

The aims of this study were to evaluate the effects of sodium tanshinone IIA sulfonate (STS) on left ventricular (LV) remodelling after for ST-elevated myocardial infarction (STEMI).

METHODS AND RESULTS

In this prospective, randomized clinical trial, 101 patients with the ST-elevated MI (STEMI) and a successful reperfusion were immediately randomized to receive STS (80 mg qd for 7 days) or saline control, along with standard therapy. The primary effectiveness endpoint is the % change in LV end diastolic volumes index (%∆ LVEDVi) as measured by echocardiography from baseline to 6 months. Secondary effectiveness endpoints include 6-month period for major adverse cardiac events (MACE), including the occurrence of recurrent myocardial infarction, death, hospitalization for heart failure and malignant arrhythmia. The 6-month changes in %∆ LVEDVi were significantly smaller in the STS group than in the control group [-5.05% vs 3.32%; P < 0.001]. With respect to MACE, there was a significant difference between those who received STS (8.16%) and those patients on control (26.00%) (P = 0.019). Meaningfully, results of parallel tests aimed at mechanistic explanation of the reported clinical effects, revealed a significantly reduced levels of neutrophils-derived granule components in the blood of STS treated patients.

CONCLUSION

We found that short-term treatment with STS reduced progressive left ventricular remodelling and subsequent better clinical outcome that could be mechanistically linked to the inhibition of the ultimate damage of infarcted myocardium by infiltrating neutrophils.

Myeloperoxidase - A bridge linking inflammation and oxidative stress with cardiovascular disease

Myeloperoxidase (MPO) is a member of the superfamily of heme peroxidases that is mainly expressed in neutrophils and monocytes. MPO-derived reactive species play a key role in neutrophil antimicrobial activity and human defense against various pathogens primarily by participating in phagocytosis. Elevated MPO levels in circulation are associated with inflammation and increased oxidative stress. Multiple lines of evidence suggest an association between MPO and cardiovascular disease (CVD) including coronary artery disease, congestive heart failure, arterial hypertension, pulmonary arterial hypertension, peripheral arterial disease, myocardial ischemia/reperfusion-related injury, stroke, cardiac arrhythmia and venous thrombosis. Elevated MPO levels are associated with a poor prognosis including increased risk for overall and CVD-related mortality. Elevated MPO may signify an increased risk for CVD for at least 2 reasons. First, low-grade inflammation and increased oxidative stress coexist with many metabolic abnormalities and comorbidities and consequently an elevated MPO level may represent an increased cardiometabolic risk in general. Second, MPO produces a large number of highly reactive species which can attack, destroy or modify the function of every known cellular component. The most common MPO actions relevant to CVD are generation of dysfunctional lipoproteins with an increased atherogenicity potential, reduced NO availability, endothelial dysfunction, impaired vasoreactivity and atherosclerotic plaque instability. These actions strongly suggest that MPO is directly involved in the pathophysiology of CVD. In this regard MPO may be seen as a mediator or an instrument through which inflammation promotes CVD at molecular and cellular level. Clinical value of MPO therapeutic inhibition remains to be tested.

Myeloperoxidase activity and acute coronary syndrome survival: long-term evaluation in the ERICO study

AIM

We aimed to analyze the influence of myeloperoxidase (MPO) activity on mortality in the Acute Coronary Syndrome Registry Strategy (ERICO) study.

METHODS

MPO activity levels were evaluated in 342 patients. We performed survival analyses using Kaplan-Meier curves and Cox regression with respective hazard ratios, 95% CI, according to MPO tertiles distribution up to 7 years of follow-up.

RESULTS

Higher MPO activity levels were seen in men, smokers, diabetics and those who were taking aspirin. MPO activity levels were neither significant in relation to mortality nor to survival rates up to seven years.

CONCLUSION

We found no relationship between elevated levels of MPO activity post-acute coronary syndrome and mortality up to 7-years of follow-up in the ERICO study.

Proteomic Discovery and Validation of the Confounding Effect of Heparin Administration on the Analysis of Candidate Cardiovascular Biomarkers

BACKGROUND

Several plasma proteins have been suggested as markers for a variety of cardiovascular conditions but fail to qualify in independent patient cohorts. This may relate to interference of medication on plasma protein concentrations. We used proteomics to identify plasma proteins that changed in concentration with heparin administration and therefore potentially may confound their evaluation as biomarkers in situations in which heparin is used.

METHODS

We used a proteomic approach based on isobaric tagging and nano-LC-MS/MS analysis to quantify several hundred proteins in a discovery study in which individual plasma samples from 9 patients at intravascular ultrasound follow-up 12 months after an acute myocardial infarction before heparin administration and 2, 15, and 60 min after heparin administration; we validated our findings in 500 individual plasma samples obtained at admission from patients with suspected ST segment elevation myocardial infarction (STEMI), of whom 363 were treated with heparin before admission.

RESULTS

In the discovery study, 25 of 653 identified plasma proteins displayed a changed concentration after heparin administration (Bonferroni-corrected P value at P &lt; 7.66 × 10−5). Fourteen of the proteins changed significantly among heparin-treated patients in the validation study (nominal significance level of P &lt; 6.92 × 10−5). Among heparin-affected proteins in both the discovery study and the validation study were midkine, spondin 1, secreted frizzled-like protein 1, lipoprotein lipase, and follistatin, all previously associated with STEMI.

CONCLUSIONS

Medications such as heparin administration given before blood sampling may confound biomarker discovery and should be carefully considered in such studies.

Role of myeloperoxidase in early diagnosis of acute myocardial infarction in patients admitted with chest pain

Myeloperoxidase (MPO) is an inflammatory marker, elevated in acute coronary syndromes (ACSs), especially in acute myocardial infarction (AMI) cases. This study aimed to evaluate the diagnostic power of MPO in AMI patients. MPO, creatine kinase (CK) MB, and Troponin I (cTn I) were performed for all study patients. Area under the curves (AUCs) and 95% confidence intervals (CI); P values of baseline levels of MPO for discriminating AMI patients from noncoronary chest pain (NCCP) patients, stable angina (SA) patients, and unstable angina (UA) patients were 0.91, 95% CI: 0.82-0.99; P < 0.0001, 0.87, 95% CI: 0.77-0.98; P < 0.0001, and 0.72, 95% CI: 0.58-0.85; P = 0.002, respectively. For diagnosing AMI from ACS patients, MPO was the most efficient marker than others markers with efficiency 82.5% within 0-6 hr after the onset time of chest pain. A predictive score that depends on a combination of baseline levels of three markers (MPO, CK-MB, and TnI) was correctly discriminated 91% of the AMI patients with high specificity 76%. In conclusion, the use of baseline levels of three biomarkers in combination could confer the information that is required for best available early diagnosis of AMI.

Utility of myeloperoxidase in the differential diagnosis of acute coronary syndrome

OBJECTIVES

To determine the usefulness of myeloperoxidase in discriminating between patients with acute coronary syndrome and patients with chest pain by other causes.

METHODS

The study included all patients over 18 years of age who come consecutively to the emergency department from September 2015 to December 2015 with chest pain of non-traumatic origin. The initial patient evaluation was performed according to the study protocol for patients with suspected acute coronary syndrome (ACS) in our Emergency Department. This included the serial measurement of troponin, and in this case myeloperoxidase, with serialization on admission and at 6h. For the determination of myeloperoxidase (MPO), a single step sandwich enzyme immunoassay by Siemens, automated on a Dimension analyser, was used.

RESULTS

Statistically significant differences were observed in the concentration of myeloperoxidase at time 0 among patients diagnosed with ACS: 505 (413)pmol/L, and non-ACS patients: 388 (195)pmol/L (p<.001), as well as at 6h (p<.001). An area under the curve ROC of 0.824 was obtained at 6h for ACS patients, with a confidence interval of 95% from 0.715 to 0.933 and a level of significance of p<.001. Statistically significant differences were also found in the concentration of myeloperoxidase at time 0 and at 6h among patients with ACS and patients with heart disease other than coronary artery disease.

CONCLUSIONS

The concentration of MPO helps to differentiate between ACS and non-ACS patients, as well as between ACS patients and patients with heart diseases other than coronary artery disease.

Altered Expression of TXNIP in the peripheral leukocytes of patients with coronary atherosclerotic heart disease

BACKGROUND

Coronary atherosclerotic heart disease (CAD) is mainly caused by atherosclerosis, an inflammatory disease characterized by plaque formation in arteries. Reactive oxygen species caused structural damage and dysfunction of arterial endothelial cells. Thioredoxin-interacting protein (TXNIP) is the endogenous inhibitor and regulator of thioredoxin, a major cellular antioxidant and antiapoptotic system. In order to explore the role of TXNIP in the occurrence and development of CAD, we detected the TXNIP expression and discussed its molecular mechanisms in CAD.

METHODS

The mRNA levels of TXNIP gene in peripheral leucocytes were detected in CAD and healthy controls (CTR) by quantitative real-time polymerase chain reaction. And TXNIP proteins were detected by western blotting.

RESULTS

TXNIP gene expression levels in patients with unstable angina pectoris (UAP, n = 96) were significantly increased compared with those of CTR (n = 192, P < .05). However, the situation is different in acute myocardial infarction (n = 96, P > .05). Logistic regression analysis showed that TXNIP levels were significantly positive correlated with UAP (OR = 1.728, P < .05).

CONCLUSIONS

TXNIP gene expression in the peripheral leucocytes was increased in patients with UAP, indicating that TXNIP in circulating leucocytes may be involved in the pathogenesis of UAP.

Relation between high levels of myeloperoxidase in the culprit artery and microvascular obstruction, infarct size and reverse remodeling in ST-elevation myocardial infarction

MAIN OBJECTIVE

To better understand the role of myeloperoxidases (MPO) in microvascular obstruction (MO) phenomenon and infarct size (IS) using cardiac magnetic resonance (CMR) data in patients with acute myocardial infarction (AMI).

METHOD

40 consecutive patients classified according to the median level of MPO in the culprit artery. A CMR study was performed during the week following AMI and at 6 months, with late gadolinium enhancement sequences.

RESULTS

Persistent MO was observed in the same proportion (50 vs. 65%, p = 0.728) between the low vs. high MPO group levels. However, the extent of the microvascular obstruction was significantly greater in the high-MPO group (6 (0-9) vs.16.5 (0-31), p = 0.027), together with a greater infarct size, and a trend towards a lower left ventricular ejection fraction (LVEF) (p = 0.054) at one week. CMR data at 6 months showed that reverse systolic remodeling was two fold more present in the low-MPO group (p = 0.058). Interestingly, the extent of MO (8.5 (6.5-31) vs. 4.1 (3-11.55), p = 0.042) and IS remained significantly greater (24.5 (9.75-35) vs. 7.5 (2.5-18.75), p = 0.022) in the high-MPO group. Moreover, MPO in the culprit artery appeared to correlate positively with MPO in non-culprit arteries and serum, and with troponin levels and peak CK.

CONCLUSION

This patient-based study revealed in patients after AMI that high MPO levels in the culprit artery were associated with more severe microvascular obstruction and greater IS. These findings may provide new insights pathophysiology explanation for the adverse prognostic impact of MO.

Relationship between Serum Inflammatory Biomarkers and Thrombus Characteristics in Patients with ST Segment Elevation Myocardial Infarction

OBJECTIVES

To compare angiographic and optical coherence tomography (OCT) data pertinent to thrombi, along with the histologic characteristics of aspirated thrombi in patients presenting with ST elevation myocardial infarction (STEMI) with or without inflammation, as assessed by C-reactive protein (CRP) and myeloperoxidase (MPO).

METHODS

In the OCTAVIA (Optical Coherence Tomography Assessment of Gender Diversity in Primary Angioplasty) study, 140 patients with STEMI referred for primary percutaneous intervention were enrolled. The patients underwent OCT assessment of the culprit vessel, along with blood sampling of CRP and MPO, and histologic analysis of the thrombus.

RESULTS

Biomarkers were available for 129 patients, and histology and immunohistochemistry of the thrombi were available for 78 patients. Comparisons were made using the median thresholds of CRP and MPO (2.08 mg/L and 604.124 ng/mL, respectively). There was no correlation between CRP and MPO levels in the whole population (p = 0.685). Patients with high CRP levels had higher thrombus grades and more frequent TIMI flow 0/1 compared with those with low CRP levels (5 [1st quartile 3; 3rd quartile 5] vs. 3.5 mg/L [1; 5], p = 0.007, and 69.3 vs. 48.5%, p = 0.04, respectively). Patients with high MPO levels more commonly had early thrombi than had those with low MPO levels (42.5 vs. 20.0%, p = 0.04).

CONCLUSIONS

CRP and MPO were not correlated in STEMI patients, possibly reflecting different pathogenic mechanisms, with CRP more related to thrombus burden and MPO to thrombus age.

The roles of myeloperoxidase in coronary artery disease and its potential implication in plaque rupture

Atherosclerosis is the main pathophysiological process underlying coronary artery disease (CAD). Acute complications of atherosclerosis, such as myocardial infarction, are caused by the rupture of vulnerable atherosclerotic plaques, which are characterized by thin, highly inflamed, and collagen-poor fibrous caps. Several lines of evidence mechanistically link the heme peroxidase myeloperoxidase (MPO), inflammation as well as acute and chronic manifestations of atherosclerosis. MPO and MPO-derived oxidants have been shown to contribute to the formation of foam cells, endothelial dysfunction and apoptosis, the activation of latent matrix metalloproteinases, and the expression of tissue factor that can promote the development of vulnerable plaque. As such, detection, quantification and imaging of MPO mass and activity have become useful in cardiac risk stratification, both for disease assessment and in the identification of patients at risk of plaque rupture. This review summarizes the current knowledge about the role of MPO in CAD with a focus on its possible roles in plaque rupture and recent advances to quantify and image MPO in plasma and atherosclerotic plaques.

Puerarin attenuates severe burn-induced acute myocardial injury in rats

BACKGROUND

Puerarin, the main isoflavone glycoside extracted from the root of Pueraria lobata, is widely prescribed for patients with cardiovascular disorders in China. This study investigates the effect of puerarin on severe burn-induced acute myocardial injury in rats and its underlying mechanisms.

MATERIALS AND METHODS

Healthy adult Wistar rats were divided into three groups: (1) sham group, sham burn treatment; (2) burn group, third-degree burns over 30% of the total body surface area (TBSA) with lactated Ringer's solution for resuscitation; and (3) burn plus puerarin group, third-degree burns over 30% of TBSA with lactated Ringer's solution containing puerarin for resuscitation. The burned animals were sacrificed at 1, 3, 6, 12, and 24 h after burn injury. Myocardial injury was evaluated by analyzing serum creatine kinase MB fraction (CK-MB) activity and cardiac troponin T (cTNT) level. Changes in cardiomyocyte ultrastructure were also determined using a transmission electron microscope. Tumor necrosis factor (TNF)-α concentration in serum was measured by radioimmunoassay. Cardiac myeloperoxidase (MPO) activity and malondialdehyde (MDA) concentration were measured to determine neutrophil infiltration and oxidative stress in the heart, respectively. The expression of p38 mitogen-activated protein (MAP) kinase in the heart was determined by Western blot analysis.

RESULTS

After the 30% TBSA full-thickness burn injury, serum CK-MB activities and cTnT levels increased markedly, both of which were significantly decreased by the puerarin treatment. The level of serum TNF-α concentration in burn group at each time-point was obviously higher than those in sham group (1.09±0.09 ng/ml), and it reached the peak value at 12 h post burn. Burn trauma also resulted in worsen ultrastructural condition, elevated MPO activity and MDA content in heart tissue, and a significant activation of cardiac p38 MAP kinase. Administration of puerarin improved the ultrastructural changes in cardiomyocytes, decreased TNF-α concentration in serum as well as suppressed cardiac MPO activity and reduced MDA content, and abolished the activation of p38 MAP kinase in heart tissue after severe burn.

CONCLUSIONS

These results suggest that puerarin attenuates inflammatory responses, reduces neutrophil infiltration and oxidative stress in the heart, and protects against acute myocardial injury induced by severe burn.

Temporal cardiac remodeling post-myocardial infarction: dynamics and prognostic implications in personalized medicine

Despite dramatic improvements in short-term mortality rates following myocardial infarction (MI), long-term survival for MI patients who progress to heart failure remains poor. MI occurs when the left ventricle (LV) is deprived of oxygen for a sufficient period of time to induce irreversible necrosis of the myocardium. The LV response to MI involves significant tissue, cellular, and molecular level modifications, as well as substantial hemodynamic changes that feedback negatively to amplify the response. Inflammation to remove necrotic myocytes and fibroblast activation to form a scar are key wound healing responses that are highly variable across individuals. Few biomarkers of early remodeling stages are currently clinically adopted. The discovery of underlying pathophysiological mechanisms and associated novel biomarkers has the potential of improving prognostic capability and therapeutic monitoring. Combining these biomarkers with other prominent ones could constitute a powerful diagnostic and prognostic tool that directly reflects the pathophysiological remodeling of the LV. Understanding temporal remodeling at the tissue, cellular, and molecular level and its link to a well-defined set of biomarkers at early stages post-MI is a prerequisite for improving personalized care and devising more successful therapeutic interventions. Here we summarize the integral mechanisms that occur during early cardiac remodeling in the post-MI setting and highlight the most prominent biomarkers for assessing disease progression.

Associations between circulating proteins and corresponding genes expressed in coronary thrombi in patients with acute myocardial infarction

INTRODUCTION

Several genes are expressed in aspirated coronary thrombi in acute myocardial infarction (AMI), exhibiting dynamic changes along ischemic time. Whether soluble biomarkers reflect the local gene environment and ischemic time is unclear. We explored whether circulating biomarkers were associated with corresponding coronary thrombi genes and total ischemic time.

MATERIAL AND METHODS

In 33 AMI patients undergoing percutaneous coronary intervention (PCI), blood samples were collected within 6-24h for markers related to plaque rupture (metalloproteinase 9, tissue inhibitor of metalloproteinases 1), platelet and endothelial cell activation (P-selectin, CD40 ligand, PAR-1), hemostasis (tissue factor, tissue plasminogen activator, plasminogen activator inhibitor 1, free and total tissue factor pathway inhibitor, D-dimer, prothrombin fragment 1+2), inflammation (interleukin 8 and 18, fractalkine, monocyte chemoattractant protein 1 (MCP-1), CXCL1, pentraxin 3, myeloperoxidase) and galectin 3, caspase 8 and epidermal growth factor (EGF). Laboratory analyses were performed by Proximity Extension Assay (Proseek Multiplex CVD I(96 × 96)), ELISAs and RT-PCR.

RESULTS

Only circulating P-selectin correlated to the corresponding P-selectin gene expression in thrombi (r=0.530, p=0.002). Plasma galectin 3, fractalkine, MCP-1 and caspase 8 correlated inversely to ischemic time (r=-0.38-0.50, all p <0.05), while plasma MCP-1, galectin 3 and EGF were higher at short (≤ 4 h) vs. long (>4h) ischemic time (all p <0.05).

CONCLUSIONS

The dynamic changes in circulating mediators along ischemic time were not reflected in the profile of locally expressed genes. These observations indicate a locally confined milieu within the site of atherothrombosis, which may be important for selective therapy.

B-Type natriuretic peptide suppression of neutrophil superoxide generation: mechanistic studies in normal subjects

Many acute cardiovascular disease states are associated with neutrophil infiltration of myocardium and subsequent release of superoxide (O2 (-) ) and myeloperoxidase (MPO), which contribute to inflammatory reactions. B-Type natriuretic peptide (BNP) is known to exert anti-inflammatory and antifibrotic effects, but it is not known whether these may include interactions with neutrophils. In neutrophils isolated from 20 healthy subjects, we assessed the effect of BNP on the 'neutrophil burst' (O2 (-) production and MPO release) stimulated by phorbol myristate acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (fMLP), respectively. Effects of BNP on cGMP accumulation, and the effects of the cell-permeable cGMP analogue 8-(4-chlorophenylthio) guanosine-cGMP (8-p-CPT-cGMP) and protein kinase G (PKG) inhibition with KT5823 on the neutrophil-BNP interaction were also evaluated. B-Type natriuretic peptide suppressed O2 (-) release from neutrophils by 23 ± 6% (P < 0.001) and 24 ± 8% (P < 0.05) following PMA and fMLP stimulation, respectively. Although BNP did not significantly increase cGMP formation, 8-p-CPT-cGMP suppressed both PMA- and fMLP-induced neutrophil O2 (-) release by 16% and 28%, respectively (P < 0.05). The PKG inhibitor KT5823 attenuated the effects of BNP on both fMLP- and PMA-associated O2 (-) production. Neither BNP nor 8-p-CPT-cGMP significantly affected MPO release from neutrophils. Suppression of O2 (-) release from neutrophils by BNP may contribute to its anti-inflammatory and antifibrotic actions.

The Effect of Intracoronary Stem Cell Injection on Markers of Leukocyte Activation in Acute Myocardial Infarction

BACKGROUND

Beneficial effects of stem cell treatment during acute myocardial infarction (AMI) have been suggested, but the effects on inflammation are controversial. The neutrophil cell markers pentraxin 3 (PTX3) and myeloperoxidase (MPO) are both reported to be elevated during AMI. We studied the effects of stem cell treatment in ST-elevation myocardial infarction (STEMI) on PTX3 and MPO levels.

METHODS

Subjects with STEMI undergoing percutaneous coronary intervention (PCI) were randomized to intracoronary injection of bone marrow cells (mBMCs) (n = 50) or controls (n = 50). Blood samples were drawn 1 day before mBMC injection (baseline), after 1 day, 3 days, 2 - 3 weeks and 3 months. Enzyme-linked immunosorbent assay (ELISA) and RT-PCR were used for biochemical analysis. Myocardial necrosis was quantified by single photon emission computed tomography (SPECT) and creatine kinase MB (CKMB) levels.

RESULTS

PTX3 and MPO levels did not differ between the groups at any time points. Within the mBMC group, overall changes in both variables were observed (P < 0.01), with decreased levels from baseline throughout. Within the control group, similar patterns were observed. The relative reduction of PTX3 from baseline to day 1 was significantly less pronounced in the mBMC group compared to controls (P = 0.002), whereas no differences in relative changes from baseline were observed for MPO. Plasma and gene expression levels of PTX3 in leukocytes correlated significantly at all time points (r = 0.379 - 0.448, P < 0.01, all). MPO was significantly correlated to baseline left ventricular ejection fraction (LVEF) (r = -0.229, P = 0.025) and peak CKMB (r = 0.200, P = 0.05).

CONCLUSIONS

Stem cell treatment had limited effect on plasma levels of PTX3 and MPO. The initially high PTX3 and MPO levels, the genetic regulation of PTX3 and the association between MPO and myocardial injury support the importance of neutrophil cell activation in STEMI.

Effects of apocynin, an NADPH oxidase inhibitor, on levels of ADMA, MPO, iNOS and TLR4 induced by myocardial ischemia reperfusion

PURPOSE

In this study, the effects of apocynin, an NADPH oxidase inhibitor, on the levels of inducible nitric oxide synthase (iNOS) and the toll-like receptor 4 (TLR4), which are inflammatory mediators in myocardial ischemia-reperfusion (MIR) injury, and myeloperoxidase (MPO), which is the indicator of neutrophil infiltration and the endogenous nitric oxide synthase inhibitor asymmetric dimethyl arginine (ADMA) increasing with oxidative stress were investigated.

METHODS

MIR injury was accomplished by the application of occlusion for 30 minutes and reperfusion for 120 minutes in the left anterior descending artery (LAD). In the study, 21 Sprague-Dawley male rats were divided into three groups: a sham group (n = 7); a MIR group (n = 7); and a MIR + apocynin treatment group (n = 7, before the procedure, an intraperitoneal administration of 10 mg/kg of apocynin for 15 days). After reperfusion, iNOS, TLR4, MPO and ADMA levels in myocardial tissue were measured by ELISA.

RESULTS

While myocardial TLR4, MPO and ADMA levels increased in the MIR group, these parameters were found to be decreased significantly in the group treated with apocynin. Although iNOS levels showed an increase in the MIR group compared to the sham group and a reduction in the MIR+apocynin group, there was no statistically significant difference between the groups.

DISCUSSION

In our study, the effect of the treatment of apocynin in MIR on ADMA, MPO, iNOS and TLR4 levels in myocardial tissue was shown for the first time. It is thought that apocynin treatment may show a protective effect in MIR injury by affecting oxidative stress (ADMA) and inflammatory parameters (iNOS, MPO).

Predictive value of the novel risk score BETTER (BiomarkErs and compuTed Tomography scorE on Risk stratification) for patients with unstable angina

BACKGROUND

The Braunwald classification and TIMI (Thrombolysis In Myocardial Infarction) risk score are used to stratify cardiovascular risk in patients with unstable angina (UA). However, these scores have a limited capacity in the practice of cardiology.

OBJECTIVES

This study sought to develop a new score, based on blood biomarkers and coronary computed tomographic angiography (CCTA) characteristics, for patients with UA.

PATIENTS AND METHODS

The study group consisted of 201 patients with confirmed UA. Follow-up time was 1 year; major adverse cardiac events (MACEs) included cardiovascular death, recurrent acute coronary syndrome (ACS), and re-admission to hospital. Blood biomarkers including high-sensitivity cardiac troponin T (Hs-cTnT), high-sensitivity C-reactive protein (Hs-CRP), myeloperoxidase (MPO) N-terminal pro-B-type natriuretic peptide (NT-proBNP), and ischemia-modified albumin (IMA) were measured. CCTA characteristics such as stenosis, plaque, epicardial fat volume (EFV), and calcification were evaluated. After analysis of relationships, the novel risk BETTER (BiomarkErs and compuTed Tomography scorE on Risk stratification) score was assessed in 201 patients.

RESULTS

In all, 25 MACEs (12.44 %) occurred: 2 cardiac deaths (1.00 %), 13 non-fatal myocardial infarctions (6.47 %), 10 recurrent ACS and re-admission in hospital (4.96 %). Serum levels of MPO, NT-proBNP, Hs-TnT, Hs-CRP, and IMA were correlated with MACEs (r = 0.20, r = 0.40, r = 0.18, r = 0.24, p < 0.01, respectively; r = 0.12, p > 0.05). CCTA characteristics of stenosis, plaque, EFV, and calcification were significantly correlated with MACEs (r = 0.53, r = 0.57, r = 0.42, and r = 0.52, all p < 0.01 respectively) and were significantly higher in the MACEs group than in the non-MACEs group. Thus, a new risk score was created combining biomarkers and CCTA statistics into a Cox multivariable for risk prediction of 1-year MACEs: BETTER risk score = MPO•0.1 + Hs-TnT•50 + Hs-CRP•0.4 + stenosis•9 + plaque•13 + EFV•0.2. The areas under the curve (AUC) for the prediction by Hs-cTnT, Hs-CRP, and MPO were 0.536 (95 % CI 0.409-0.662), 0.745 (95 % CI 0.641-0.850), and 0.650 (95 % CI 0.541-0.760), respectively. The AUC for the prediction of CCTA characteristics of stenosis, plaque, and EFV were 0.905 (95 % CI 0.860-0.950), 0.912 (95 % CI 0.867-0.957), and 0.835 (95 % CI 0.752-0.917), respectively. In addition, the AUC was 0.621 (95 % CI 0.492-0.750) for the Braunwald classification and 0.680 (95 % CI 0.559-0.801) for the TIMI score. The AUC for the BETTER risk score was 0.937 (95 % CI 0.902-0.972).

CONCLUSION

The BETTER risk score is new tool specifically developed for patients with UA. The score displays higher prediction accuracy in terms of discrimination and calibration than other currently available scores for risk stratification.

Myeloperoxidase upregulates endothelin receptor type B expression

Neutrophil recruitment and activation are principal events in inflammation. Upon activation neutrophils release myeloperoxidase (MPO), a heme enzyme, which binds to and transcytoses endothelial cells. Whereas the significance of the subendothelial deposition of MPO has evolved as a critical prerequisite for the enzyme's suppression of nitric oxide (NO⋅) bioavailability, the functional consequences of MPO binding to and interaction with endothelial and smooth muscle cells remain poorly understood. Cultured human endothelial cells (HUVECs) were exposed to MPO. Gene expression of the endothelin receptor type B (ETRB), which is critically involved not only in endothelin-1 clearance, but also in endothelin-mediated vasoconstriction, was significantly increased. Real time PCR, Western blotting and immunofluorescence confirmed up-regulation of ETRB in MPO-treated endothelial cells. Inhibition of MPO's enzymatic activity blunted the increase in ETRB protein expression. Treatment of the cells with the MAP kinase inhibitors PD98059 or SB203580 indicates that MPO activates ETRB expression via MAP kinase pathways. On human smooth muscle cells (HAoSMCs), which not only express the endothelin receptor type B (ETRB) but also express the endothelin receptor type A (ETRA), MPO also stimulated ETRB expression as opposed to ETRA expression, which remained unchanged. Functional ex vivo organ bath chamber studies with MPO-incubated rat femoral artery sections revealed increased ETRB agonist dependent constriction. Binding of MPO to endothelial and vascular smooth muscle cells increases expression of the endothelin receptor type B (ETRB) via classical MAP kinase pathways. This suggests that MPO not only affects vasomotion by reducing the bioavailability of vasodilating molecules but also by increasing responsiveness to vasoconstrictors, further advocating for MPO as a central, leukocyte-derived regulator of vascular tone.

Myeloperoxidase may help to differentiate coronary plaque erosion from plaque rupture in patients with acute coronary syndromes

Coronary thrombosis is the most frequent final event leading to an acute coronary syndrome. In approximately two-thirds of cases, the thrombus overlies a ruptured plaque, whereas in one-third of cases it overlies an intact plaque with superficial endothelial erosion, a finding showed initially by histopathological postmortem studies and more recently confirmed by in vivo optical coherence tomography imaging. Interestingly, recent observations suggest that mechanisms leading to plaque rupture or erosion are different. In fact, in a recent study, we showed that myeloperoxidase levels in peripheral blood and expression within thrombi overlying the culprit plaque are much higher in patients with plaque erosion than in those with plaque rupture. These observations suggest that innate immunity activation is likely to play a key role, in particular, in plaque erosion and might become a therapeutic target in this subset of patients.

Diagnostic and Prognostic Performance of Myeloperoxidase Plasma Levels Compared With Sensitive Troponins in Patients Admitted With Acute Onset Chest Pain

Background—

Activation of leukocytes with release of myeloperoxidase (MPO) has been linked to acute coronary disease. To date, studies investigating the diagnostic and prognostic performance of circulating MPO in patients with chest pain (CP) are mainly retrospective, of low size, and lack a cut-off value for MPO. Herein, we prospectively assess the diagnostic and prognostic properties of MPO compared with sensitive troponin I (sTNI) in patients admitted to the emergency room with CP.

Methods and Results—

One thousand, eight hundred and eighteen consecutive patients (mean age, 61.4±13.5 years; 33.6% female) admitted for CP underwent determination of MPO, sTnI, and B-natriuretic peptide plasma levels at admission and 3 hours and 6 hours thereafter. A cut-off for MPO was defined in 5000 population-based subjects. Baseline MPO levels were elevated in patients with acute myocardial infarction compared with patients with noncoronary CP. For all time-points accuracy of MPO was inferior to sTNI for predicting AMI. The sensitivity of MPO to diagnose AMI at presentation was 73.5% compared with 90.7% for sTNI, and the specificity of MPO was 45.5% as opposed to 90.2%. B-natriuretic peptide levels also failed to demonstrate independent diagnostic information. Both MPO and B-natriuretic peptide were predictive for increased risk of adverse events at 30 days and 6 months, whereas their predictive value was weakened after covariate adjustment.

Conclusions—

The data demonstrate that MPO and B-natriuretic peptide fail to provide incremental information for patients with acute onset CP when added to sensitive troponin. However, there is a potential value for both biomarkers as prognostic markers.

Serum levels of gelatinase associated lipocalin as indicator of the inflammatory status in coronary artery disease

Background. Atherosclerosis is a chronic inflammatory disease and the acute clinical manifestations represent acute on chronic inflammation. Neutrophil gelatinase-associated lipocalin (NGAL) is found in the granules of human neutrophils, with many diverse functions. The aim of this study was to evaluate the hypothesis that levels NGAL in blood may reflect the inflammatory process in various stages of coronary artery disease. Methods. We studied 140 patients, with SA 40, UA 35, NSTEMI 40, and STEMI 25, and 20 healthy controls. Serum NGAL was measured upon admission and before coronary angiography. Results. Significant differences were observed in median serum-NGAL(ng/mL) between patients with SA (79.23 (IQR, 37.50–100.32)), when compared with UA (108.00 (68.34–177.59)), NSTEMI (166.49 (109.24–247.20)), and STEMI (178.63 (111.18–305.92)) patients and controls (50.31 (44.30–69.78)) with significant incremental value from SA to STEMI. We observed a positive and significant correlation between serum-NGAL and hs-CRP (spearman coefficient rho = 0.685, P < 0.0001) as well as with neutrophil counts (r = 0.511, P < 0.0001). Conclusions. In patients with coronary artery disease serum levels of NGAL increase and reflect the degree of inflammatory process. In patients with acute coronary syndromes, serum levels of NGAL have high negative predictive value and reflecting the inflammatory status could show the severity of coronary clinical syndrome.

Neutrophilic inflammatory response and oxidative stress in premenopausal women chronically exposed to indoor air pollution from biomass burning

The possibility of inflammation and neutrophil activation in response to indoor air pollution (IAP) from biomass fuel use has been investigated. For this, 142 premenopausal, never-smoking women (median age, 34 years) who cook exclusively with biomass (wood, dung, crop wastes) and 126 age-matched control women who cook with cleaner fuel liquefied petroleum gas (LPG) were enrolled. The neutrophil count in blood and sputum was significantly higher (p < 0.05) in biomass users than the control group. Flow cytometric analysis revealed marked increase in the surface expression of CD35 (complement receptor-1), CD16 (F(C)γ receptor III), and β(2) Mac-1 integrin (CD11b/CD18) on circulating neutrophils of biomass users. Besides, enzyme-linked immunosorbent assay showed that they had 72%, 67%, and 54% higher plasma levels of the proinflammatory cytokines tumor necrosis factor-alpha, interleukin-6, and interleukin-12, respectively, and doubled neutrophil chemoattractant interleukin-8. Immunocytochemical study revealed significantly higher percentage of airway neutrophils expressing inducible nitric oxide synthase, while the serum level of nitric oxide was doubled in women who cooked with biomass. Spectrophotometric analysis documented higher myeloperoxidase activity in circulating neutrophils of biomass users, suggesting neutrophil activation. Flow cytometry showed excess generation of reactive oxygen species (ROS) by leukocytes of biomass-using women, whereas their erythrocytes contained a depleted level of antioxidant enzyme superoxide dismutase (SOD). Indoor air of biomass-using households had two to four times more particulate matter with diameters of <10 μm (PM(10)) and <2.5 μm (PM(2.5)) as measured by real-time laser photometer. After controlling potential confounders, rise in proinflammatory mediators among biomass users were positively associated with PM(10) and PM(2.5) in indoor air, suggesting a close relationship between IAP and neutrophil activation. Besides, the levels of neutrophil activation and inflammation markers were positively associated with generation of ROS and negatively with SOD, indicating a role of oxidative stress in mediating neutrophilic inflammatory response following chronic inhalation of biomass smoke.

An intense and short-lasting burst of neutrophil activation differentiates early acute myocardial infarction from systemic inflammatory syndromes

Background

Neutrophils are involved in thrombus formation. We investigated whether specific features of neutrophil activation characterize patients with acute coronary syndromes (ACS) compared to stable angina and to systemic inflammatory diseases.

Methods and Findings

The myeloperoxidase (MPO) content of circulating neutrophils was determined by flow cytometry in 330 subjects: 69 consecutive patients with acute coronary syndromes (ACS), 69 with chronic stable angina (CSA), 50 with inflammation due to either non-infectious (acute bone fracture), infectious (sepsis) or autoimmune diseases (small and large vessel systemic vasculitis, rheumatoid arthritis). Four patients have also been studied before and after sterile acute injury of the myocardium (septal alcoholization). One hundred thirty-eight healthy donors were studied in parallel. Neutrophils with normal MPO content were 96% in controls, >92% in patients undergoing septal alcoholization, 91% in CSA patients, but only 35 and 30% in unstable angina and AMI (STEMI and NSTEMI) patients, compared to 80%, 75% and 2% of patients with giant cell arteritis, acute bone fracture and severe sepsis. In addition, in 32/33 STEMI and 9/21 NSTEMI patients respectively, 20% and 12% of neutrophils had complete MPO depletion during the first 4 hours after the onset of symptoms, a feature not observed in any other group of patients. MPO depletion was associated with platelet activation, indicated by P-selectin expression, activation and transactivation of leukocyte β2-integrins and formation of platelet neutrophil and -monocyte aggregates. The injection of activated platelets in mice produced transient, P-selectin dependent, complete MPO depletion in about 50% of neutrophils.

Conclusions

ACS are characterized by intense neutrophil activation, like other systemic inflammatory syndromes. In the very early phase of acute myocardial infarction only a subpopulation of neutrophils is massively activated, possibly via platelet-P selectin interactions. This paroxysmal activation could contribute to occlusive thrombosis.

Neutrophil gelatinase-associated lipocalin in acute kidney injury

Acute kidney injury (AKI) is recognized as an independent risk factor for morbidity and mortality. Unfortunately, this syndrome was historically underdiagnosed due to inconsistent definition of AKI as well as insensitive and nonspecific diagnostic tools. Recent advances in defining AKI, understanding its pathophysiology, and improving its diagnostic accuracy have an impact in disease management and clinical outcome. Prompt recognition and treatment of AKI still remains the cornerstone of clinical management of this syndrome. This chapter focuses on the recent advances in diagnosis of AKI using novel serum and urine biomarkers. The role of neutrophil gelatinase-associated lipocalin (NGAL) in pathophysiology and diagnosis of AKI is presented. A detailed analysis of the biology of NGAL and presentation of laboratory methods of measurement is also provided. The role of NGAL as biomarker beyond the boundaries of nephrology is also presented.

Myocardial protective effect by ulinastatin via an anti-inflammatory response after regional ischemia/reperfusion injury in an in vivo rat heart model

Background

Ulinastatin has anti-inflammatory properties and protects organs from ischemia/reperfusion-induced injury. The aim of this study was to investigate whether ulinastatin provides a protective effect on a regional myocardial ischemia/reperfusion injury in an in vivo rat heart model and to determine whether the anti-inflammatory response is related to its myocardial protective effect.

Methods

Rats were randomized to two groups. One group is received ulinastatin (50,000 U/kg or 100,000 U/kg) diluted in normal saline and the other group is received normal saline, which was administered intraperitoneally 30 min before the ischemic insult. Reperfusion after 30 min of ischemia of the left coronary artery territory was applied. Hemodynamic measurements were recorded serially during 6 h after reperfusion. After the 6 h reperfusion, myocardial infarct size, cardiac enzymes, myeloperoxidase activity, and inflammatory cytokine levels were compared between the ulinastatin treated and untreated groups.

Results

Ulinastatin improved cardiac function and reduced infarct size after regional ischemia/reperfusion injury. Ulinastatin significantly attenuated tumor necrosis factor-α expression and reduced myeloperoxidase activity.

Conclusions

Ulinastatin showed a myocardial protective effect after regional ischemia/reperfusion injury in an in vivo rat heart model. This protective effect of ulinastatin might be related in part to ulinastatin's ability to inhibit myeloperoxidase activity and decrease expression of tumor necrosis factor-α.

Risk prediction with serial myeloperoxidase monitoring in patients with acute chest pain

BACKGROUND

Although myeloperoxidase (MPO) monitoring is predictive for cardiovascular outcomes in suspected acute coronary syndromes, the value of serial testing is unknown.

METHODS

We investigated the relationship between serial MPO concentrations in 490 individuals with acute chest pain and incident major adverse cardiac events (MACE) during 6 months of follow-up. We measured MPO with the CardioMPO assay, and cardiac troponin I (cTnI), with the Abbott Architect assay.

RESULTS

Plasma MPO concentrations during the first 16 h were higher in individuals who experienced MACE. Higher MPO quartiles predicted a greater likelihood of 6-month MACE at baseline [OR (95% CI), 2.4 (1.4-4.1), P = 0.001 for highest vs lowest quartile] and all subsequent time points, with strongest predictive ability found in 16-h postbaseline samples [9.9 (4.7-20.9), P < 0.001 for highest vs lowest quartile]. MPO was predictive for MACE among individuals whose cTnI remained within reference intervals (<0.028 μg/L). The lowest rate of missed cases was found when MPO was <640 pmol/L at baseline and all other time points. Serial MPO monitoring predicted MACE risk better than baseline MPO measurements alone (c statistic 0.813 vs 0.602; P = 0.002), including in individuals whose cTnI remained within reference intervals (c statistic 0.903; P = 0.009). Combined serial cTnI and MPO testing improved accuracy for predicting 6-month MACE, reduced the number of missed MACE events from cTnI testing alone, and improved risk classification in 26.1% of patients.

CONCLUSIONS

MPO concentrations are predictive of outcome up to 16 h after presentation with chest pain and predict events missed by cTnI testing, supporting a potential role in rapid patient triage.

Diagnostic efficacy of myeloperoxidase for the detection of acute coronary syndromes

BACKGROUND

Early diagnosis of acute coronary syndrome (ACS) is frequently a challenging task, while immediate risk stratification remains crucial for the prompt implementation of appropriate therapy in this setting. Employing markers that increase rapidly after the symptom onset may enhance triage and therapeutic decision-making in patients suspected for ACS. Myeloperoxidase (MPO) exerting proinflammatory and pro-oxidative properties is suggested as a reliable early marker for ACS associated with unfavourable clinical outcome. We assessed the diagnostic efficacy of plasma MPO alone or in combination with cardiac troponin I (cTnI) for detecting ACS in patients presenting with chest pain initiating within 6h before the hospital admission.

MATERIAL AND METHODS

A study group consisted of 253 patients diagnosed with ACS and 47 subjects having other heart disease or unspecified chest pain. Clinically healthy volunteers (n=124) served as controls. MPO concentration was measured in plasma (Abbott Diagnostics, USA), while serum was assayed for cTnI, creatine-kinase MB, lipids, glucose, creatinine, brain natriuretic peptide type B and C-reactive protein.

RESULTS

Both MPO and cTnI values were significantly lower in non-ACS subjects than in patients with ACS. At 97·5th percentile as cut-off, the superiority of MPO over cTnI was observed in patients with unstable angina and non-ACS subjects. Considerably higher MPO concentrations were demonstrated in the troponin-negative ACS patients on admission who became troponin-positive after 6h. Combined evaluation of MPO and cTnI possessed remarkably higher sensitivity than assessment of cTnI alone in all patients with ACS.

CONCLUSIONS

Myeloperoxidase substantially facilitates the early diagnosis of ACS.

The paradox of the neutrophil's role in tissue injury

The neutrophil is an essential component of the innate immune system, and its function is vital to human life. Its production increases in response to virtually all forms of inflammation, and subsequently, it can accumulate in blood and tissue to varying degrees. Although its participation in the inflammatory response is often salutary by nature of its normal interaction with vascular endothelium and its capability to enter tissues and respond to chemotactic gradients and to phagocytize and kill microrganisms, it can contribute to processes that impair vascular integrity and blood flow. The mechanisms that the neutrophil uses to kill microorganisms also have the potential to injure normal tissue under special circumstances. Its paradoxical role in the pathophysiology of disease is particularly, but not exclusively, notable in seven circumstances: 1) diabetic retinopathy, 2) sickle cell disease, 3) TRALI, 4) ARDS, 5) renal microvasculopathy, 6) stroke, and 7) acute coronary artery syndrome. The activated neutrophil's capability to become adhesive to endothelium, to generate highly ROS, and to secrete proteases gives it the potential to induce local vascular and tissue injury. In this review, we summarize the evidence for its role as a mediator of tissue injury in these seven conditions, making it or its products potential therapeutic targets.