Is there a clinical role for oxidative stress biomarkers in atherosclerotic diseases?

Genetic and clinical study of myeloperoxidase's association with coronary artery disease

BACKGROUND

Unraveling myeloperoxidase's (MPO) correlation with coronary artery disease (CAD) and genetic variations, this study seeks to enhance diagnostic precision and therapeutic strategies.

RESULTS

CAD patients were found to be older and more male than controls. Several clinical parameters, including glucose, total bilirubin, alkaline phosphatase, creatinine, and troponin levels, showed significant variations. Moreover, CAD patients had lower red cell distribution width (RDW%) and mean platelet volume (MPV) than controls. Serum MPO levels did not differ significantly between CAD patients and controls, and no correlation was found with other clinical parameters except for glucose, creatinine, and total bilirubin.

CONCLUSIONS

The data suggest that serum MPO levels are not substantially related to CAD patients, as indicated by lower MPO levels in CAD patients compared to controls. While highlighting the potential of MPV and RDW% as predictors of severe atherosclerosis in CAD. Further research is needed to validate the diagnostic and prognostic value of RDW%, MPV, and MPO levels in CAD.

TRIAL REGISTRATION

15092021-9-12. Registered 15 September 2021.

Blood-Based and Imaging Biomarkers of Atherosclerosis

Atherosclerosis is the main cause of arterial thrombosis, causing acute occlusive cardiovascular syndromes. Numerous risk prediction models have been developed, which mathematically combine multiple predictors, to estimate the risk of developing cardiovascular events. Current risk models typically do not include information from biomarkers that can potentially improve these existing prediction models especially if they are pathophysiologically relevant. Numerous cardiovascular disease biomarkers have been investigated that have focused on known pathophysiological pathways including those related to cardiac stress, inflammation, matrix remodelling, and endothelial dysfunction. Imaging biomarkers have also been studied that have yielded promising results with a potential higher degree of clinical applicability in detection of atherosclerosis and cardiovascular event prediction. To further improve therapy decision-making and guidance, there is continuing intense research on emerging biologically relevant biomarkers. As the pathogenesis of cardiovascular disease is multifactorial, improvements in discrimination and reclassification in risk prediction models will likely involve multiple biomarkers. This article will provide an overview of the literature on potential blood-based and imaging biomarkers of atherosclerosis studied so far, as well as potential future directions.

Mechanism by Which Inflammation and Oxidative Stress Induce Mineralocorticoid Receptor Gene Expression in Aging Vascular Smooth Muscle Cells

BACKGROUND

Vascular MR (mineralocorticoid receptor) expression increases with age driving aging-associated vascular stiffness and hypertension. MR has two isoforms (1α and 1β) with distinct 5'-untranslated and promoter sequences (P1 and P2), but the gene regulatory mechanisms remain unknown. We investigated mechanisms driving MR gene transcriptional regulation in aging human smooth muscle cells (SMC).

METHODS

MR was quantified in aortic tissue and primary human aortic SMC (HASMC) comparing adult and aged donors and adult HASMC treated with H2O2, to induce aging. Predicted transcription factor (TF) binding sites in the MR gene were validated using chromatin immunoprecipitations and reporter assays. The impact of TF inhibitors on MR isoforms and fibrosis target gene expression was examined.

RESULTS

Expression of both MR mRNA isoforms increased with donor age or H2O2 treatment in HASMCs. HIF1α (hypoxia-inducible factor) and the inflammatory TF NFκB (nuclear factor kappa B) both increased with age in HASMCs and are predicted to bind MR promoters. H2O2 induced HIF1α and NFκB expression and DNA binding of HIF1α to the MR P1 promoter and of NFκB to both MR promoters in HASMCs. HIF1α inhibition decreased MR-1α isoform expression while NFκB inhibition decreased both MR isoforms. HIF1α, NFκB, and MR inhibition decreased the expression of a SMC-MR target gene implicated in vascular fibrosis. In human aortic tissues, expression of HIF1α and NFκB each positively correlated with donor age and MR expression (P<0.0001).

CONCLUSIONS

These data implicate the inflammatory TF, NFκB, and oxidative stress-induced TF, HIF1α, in regulating SMC MR transcription in aging HASMCs, which drives aging-related vascular stiffness and cardiovascular disease.

Olive Pomace Oil versus High Oleic Sunflower Oil and Sunflower Oil: A Comparative Study in Healthy and Cardiovascular Risk Humans

Olive pomace oil (OPO) is mainly a source of monounsaturated fat together with a wide variety of bioactive compounds, such as triterpenic acids and dialcohols, squalene, tocopherols, sterols and aliphatic fatty alcohols. To date, two long-term intervention studies have evaluated OPO’s health effects in comparison with high oleic sunflower oil (HOSO, study-1) and sunflower oil (SO, study-2) in healthy and cardiovascular risk subjects. The present study integrates the health effects observed with the three oils. Two randomized, blinded, cross-over controlled clinical trials were carried out in 65 normocholesterolemic and 67 moderately hypercholesterolemic subjects. Each study lasted fourteen weeks, with two four-week intervention phases (OPO versus HOSO or SO), each preceded by a three-week run-in or washout period. Regular OPO consumption reduced total cholesterol (p = 0.017) and LDL cholesterol (p = 0.018) levels as well as waist circumference (p = 0.026), and only within the healthy group did malondialdehyde (p = 0.004) levels decrease after OPO intake versus HOSO. Contrarily, after the SO intervention, apolipoprotein (Apo) B (p < 0.001) and Apo B/Apo A ratio (p < 0.001) increased, and to a lower extent Apo B increased with OPO. There were no differences between the study groups. OPO intake may improve cardiometabolic risk, particularly through reducing cholesterol-related parameters and waist circumference in healthy and hypercholesterolemic subjects.

Aging-Related Decline of Autophagy in Patients with Atrial Fibrillation-A Post Hoc Analysis of the ATHERO-AF Study

Background: Aging is an independent risk factor for cardiovascular diseases. The autophagy process may play a role in delaying aging and improving cardiovascular function in aging. Data regarding autophagy in atrial fibrillation (AF) patients are lacking. Methods: A post hoc analysis of the prospective ATHERO-AF cohort study, including 150 AF patients and 150 sex- and age-matched control subjects (CS), was performed. For the analysis, the population was divided into three age groups: <50−60, 61−70, and >70 years. Oxidative stress (Nox2 activity and hydrogen peroxide, H2O2), platelet activation (PA) by sP-selectin and CD40L, endothelial dysfunction (nitric oxide, NO), and autophagy parameters (P62 and ATG5 levels) were assessed. Results: Nox2 activity and H2O2 production were higher in the AF patients than in the CS; conversely, antioxidant capacity was decreased in the AF patients compared to the CS, as was NO production. Moreover, sP-selectin and CD40L were higher in the AF patients than in the CS. The autophagy process was also significantly impaired in the AF patients. We found a significant difference in oxidative stress, PA, NO production, and autophagy across the age groups. Autophagy markers correlated with oxidative stress, PA, and endothelial dysfunction in both groups. Conclusions: This study provides evidence that the autophagy process may represent a mechanism for increased cardiovascular risk in the AF population.

Mediterranean Diet: A Tool to Break the Relationship of Atrial Fibrillation with the Metabolic Syndrome and Non-Alcoholic Fatty Liver Disease

Atrial fibrillation (AF) is the most common supraventricular arrhythmia associated with increased cardiovascular and non-cardiovascular morbidity and mortality. As multiple factors may predispose the onset of AF, the prevention of the occurrence, recurrence and complications of this arrhythmia is still challenging. In particular, a high prevalence of cardio-metabolic comorbidities such as the metabolic syndrome (MetS) and in its hepatic manifestation, the non-alcoholic fatty liver disease (NAFLD), have been described in the AF population. A common pathogenetic mechanism linking AF, MetS and NAFLD is represented by oxidative stress. For this reason, in the past decades, numerous studies have investigated the effect of different foods/nutrients with antioxidant properties for the prevention of, and their therapeutic role is still unclear. In this narrative comprehensive review, we will summarize current evidence on (1) the association between AF, MetS and NAFLD (2) the antioxidant role of Mediterranean Diet and its components for the prevention of AF and (3) the effects of Mediterranean Diet on MetS components and NAFLD.

8-Isoprostanes and Asymmetric Dimethylarginine as Predictors of Mortality in Patients Following Coronary Bypass Surgery: A Long-Term Follow-Up Study

Background: We previously demonstrated that enhanced oxidative stress and reduced nitric oxide bioavailability are associated with unfavorable outcomes early after coronary artery bypass grafting. It is not known whether these processes may impact long-term results. We sought to assess whether during long-term follow-up, markers of oxidative stress and nitric oxide bioavailability may predict cardiovascular mortality following bypass surgery. Methods: We studied 152 consecutive patients (118 men, age 65.2 ± 8.3 years) who underwent elective, primary, isolated on-pump bypass surgery. We measured plasma 8-iso-prostaglandin F2α and asymmetric dimethylarginine before surgery and twice after surgery (18–36 h and 5–7 days). We assessed all-cause and cardiovascular death in relation to these two biomarkers during a mean follow-up time of 11.7 years. Results: The overall mortality was 44.7% (4.7 per 100 patient-years) and cardiovascular mortality was 21.0% (2.2 per 100 patient-years). Baseline 8-iso-prostaglandin F2α was associated with cardiovascular mortality (HR 1 pg/mL 1.010, 95% CI 1.001–1.021, p = 0.036) with the optimal cut-off ≤ 364 pg/mL for higher survival rate (HR 0.460, 95% CI 0.224–0.942, p = 0.030). Asymmetric dimethylarginine > 1.01 μmol/L measured 18–36 h after surgery also predicted cardiovascular death (HR 2.467, 95% CI 1.140–5.340, p = 0.020). Additionally, elevated 8-iso-prostaglandin F2α measured at the same time point associated with all-cause mortality (HR 1 pg/mL 1.007, 95% CI 1.000–1.014, p = 0.048). Conclusions: Our findings indicate that in advanced coronary disease, increased oxidative stress, reflected by 8-iso-prostaglandin F2α before bypass surgery and enhanced asymmetric dimethylarginine accumulation just after the surgery are associated with cardiovascular death during long-term follow-up

Interventional study with vitamin E in cardiovascular disease and meta-analysis

Cardiovascular disease (CVD) is one of the major causes of morbidity and mortality and atherosclerosis is the common root to most of the CVD. Oxidative stress is one of the most important factors driving atherosclerosis and its complications. Thus, strategies for the prevention and treatment of cardiovascular events had oxidative changes as a potential target. Natural vitamin E consists of a family of eight different compounds, four tocopherols and four tocotrienols. All tocopherols and tocotrienols are potent antioxidants with lipoperoxyl radical-scavenging activities. In addition, α-tocopherol possesses also anti-inflammatory as well as anti-atherothrombotic effects by modulating platelet and clotting system. Experimental and in vitro studies described molecular and cellular signalling pathways regulated by vitamin E antithrombotic and antioxidant properties. While observational studies demonstrated an inverse association between vitamin E serum levels and CVD, interventional trials with vitamin supplements provided negative results. This review focus on the impact of vitamin E in the atherothrombotic process and describes the results of experimental and clinical studies with the caveats related to the interventional trials with vitamin E to prevent CVD.

Cardioprotective Effects of Glucagon-like Peptide-1 (9-36) Against Oxidative Injury in H9c2 Cardiomyoblasts: Potential Role of the PI3K/Akt/NOS Pathway

ABSTRACT

Glucagon-like peptide (GLP)-1(7-36), a major active form of GLP-1 hormone, is rapidly cleaved by dipeptidyl peptidase-4 to generate a truncated metabolite, GLP-1(9-36) which has a low affinity for GLP-1 receptor (GLP-1R). GLP-1(7-36) has been shown to have protective effects on cardiovascular system through GLP-1R-dependent pathway. Nevertheless, the cardioprotective effects of GLP-1(9-36) have not fully understood. The present study investigated the effects of GLP-1(9-36), including its underlying mechanisms against oxidative stress and apoptosis in H9c2 cells. Here, we reported that GLP-1(9-36) protects H9c2 cardiomyoblasts from hydrogen peroxide (H2O2)-induced oxidative stress by promoting the synthesis of antioxidant enzymes, glutathione peroxidase-1, catalase, and heme oxygenase-1. In addition, treatment with GLP-1(9-36) suppressed H2O2-induced apoptosis by attenuating caspase-3 activity and upregulating antiapoptotic proteins, Bcl-2 and Bcl-xL. These protective effects of GLP-1(9-36) are attenuated by blockade of PI3K-mediated Akt phosphorylation and prevention of nitric oxide synthase-induced nitric oxide production. Thus, GLP-1(9-36) represents the potential therapeutic target for prevention of oxidative stress and apoptosis in the heart via PI3K/Akt/nitric oxide synthase signaling pathway.

Circulating Lipopolysaccharides and Impaired Antioxidant Status in Patients With Atrial Fibrillation. Data From the ATHERO-AF Study

Objectives: Atrial fibrillation (AF) is characterized by an oxidative imbalance, which is associated with an increased risk of cardiovascular events (CVEs). It is unclear whether low grade endotoxemia may contribute to the impaired antioxidant status in AF patients. We investigated the relationship between circulating lipopolysaccharides (LPS) and antioxidant status in AF patients.

Patients and Methods:Post-hoc analysis from the ongoing prospective observational cohort ATHERO-AF study including 907 patients. Antioxidant status was evaluated by the activity of glutathione peroxidase 3 (GPx3) and superoxide dismutase (SOD). Patients were divided into two groups to evaluate the risk of CVEs: (1) LPS below median and GPx3 above median (n = 254); (2) LPS above median and GPx3 below median (n = 263).

Results: The mean age was 73.5 ± 8.3 years, and 43.1% were women. Median LPS and GPx3 were 50.0 pg/ml [interquartile range (IQR) 15–108] and 20.0 U/ml (IQR 10.0–34.0), respectively. Patients of Groups 2 were older, with a higher prevalence of heart failure. LPS above the median was associated with reduced GPx3 [Odds Ratio for LPS 1.752, 95% Confidence Interval (CI) 1.344–2.285, p < 0.001] and SOD (OR 0.525, 95%CI 0.403–0.683) activity after adjustment for CHA₂DS₂VASc score. In a mean follow-up of 54.0 ± 36.8 months, 118 CVEs occurred, 42 in Group 1 and 76 in Group 2 (Log-Rank test p = 0.001). At multivariable Cox regression analysis, Group 2 was associated with a higher risk of CVEs [Hazard Ratio (HR) 1.644, 95%CI 1.117–2,421, p = 0.012], along with age ≥ 75 years (HR 2.035, 95%CI 1.394–2.972, p < 0.001), diabetes (HR 1.927, 95%CI 1.280–2.900, p = 0.002), and previous cerebrovascular disease (HR 1.895, 95%CI 1.251–2.870, p = 0.003) and previous cardiovascular disease (HR 1.708, 95%CI 1.149–2.538, p = 0.008).

Conclusions: Our study indicates that circulating LPS may contribute to impaired antioxidant status in patients with AF. Patients with coincidentally high LPS and reduced GPx3 activity showed the highest risk of CVEs.

Particulate matter air pollutants and cardiovascular disease: Strategies for intervention

Air pollution is consistently linked with elevations in cardiovascular disease (CVD) and CVD-related mortality. Particulate matter (PM) is a critical factor in air pollution-associated CVD. PM forms in the air during the combustion of fuels as solid particles and liquid droplets and the sources of airborne PM range from dust and dirt to soot and smoke. The health impacts of PM inhalation are well documented. In the US, where CVD is already the leading cause of death, it is estimated that PM2.5 (PM < 2.5 μm in size) is responsible for nearly 200,000 premature deaths annually. Despite the public health data, definitive mechanisms underlying PM-associated CVD are elusive. However, evidence to-date implicates mechanisms involving oxidative stress, inflammation, metabolic dysfunction and dyslipidemia, contributing to vascular dysfunction and atherosclerosis, along with autonomic dysfunction and hypertension. For the benefit of susceptible individuals and individuals who live in areas where PM levels exceed the National Ambient Air Quality Standard, interventional strategies for mitigating PM-associated CVD are necessary. This review will highlight current state of knowledge with respect to mechanisms for PM-dependent CVD. Based upon these mechanisms, strategies for intervention will be outlined. Citing data from animal models and human subjects, these highlighted strategies include: 1) antioxidants, such as vitamins E and C, carnosine, sulforaphane and resveratrol, to reduce oxidative stress and systemic inflammation; 2) omega-3 fatty acids, to inhibit inflammation and autonomic dysfunction; 3) statins, to decrease cholesterol accumulation and inflammation; 4) melatonin, to regulate the immune-pineal axis and 5) metformin, to address PM-associated metabolic dysfunction. Each of these will be discussed with respect to its potential role in limiting PM-associated CVD.

Cancer and atrial fibrillation: Epidemiology, mechanisms, and anticoagulation treatment

Cancer patients are at an increased risk of developing atrial fibrillation (AF) and thrombosis. However, the management of anticoagulation in patients with both diseases may be challenging, and data on these patients are lacking. We summarize the current evidence on the incidence and prevalence of cancer in AF and vice versa and provide some practical considerations on the management of oral anticoagulation in specific clinical situations. Low-molecular weight heparins are not approved for thromboprophylaxis in AF, and management of warfarin can be difficult. The use of direct oral anticoagulants may be particularly attractive for their rapid onset/offset action and lower bleeding risk.

Effect of Cryptotanshinone on Measures of Rat Cardiomyocyte Oxidative Stress and Gene Activation Associated with Apoptosis

BACKGROUND

Oxidative stress is a key factor that results in cardiomyocyte apoptosis and cardiovascular diseases. Cryptotanshinone (CTS), one of the major bioactive constitutes extracted from the root of the plant Salvia miltiorrhizaBunge, has been widely studied for various disease treatments. However, the roles of CTS on cardiomyocytes remain unclear.

METHODS

In the present study, neonatal rat cardiomyocytes were pretreated with CTS for 4 h before being exposed to H2O2. Cell viability for the cells with or without pretreatment with CTS before exposure to H2O2 was evaluated by the MTT assay. Production of lactate dehydrogenase (LDH), nitric oxide (NO), prostaglandin E2 (PGE2), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxides (GSH-Px) was quantified by corresponding detection kits. The mRNA levels of Bcl-2 antiapoptotic and Bax-like proapoptotic genes were quantified with RT-PCR. Production of reactive oxygen species (ROS) was qualified and quantified with a dichlorofluorescein diacetate cellular ROS detection assay kit. The extracellular signal-related kinase (ERK) phosphorylation and nuclear factor κB (NF-κB) activation were measured by Western blot.

RESULTS

Our results revealed that the CTS pretreatment could enhance cell viability and promote Bcl-2 antiapoptotic gene expression. Additionally, CTS could abolish the H2O2-induced production of NO, LDH, and PGE2. Consistent with these findings, CTS could inhibit ROS and MDA production and promote SOD, CAT, and GSH-Px activities. Mechanistically, CTS may achieve these processes by inhibiting ERK and NF-κB signal pathways.

CONCLUSION

CTS protects cardiomyocytes against the H2O2-induced cellular injuries through ERK and NF-κB inactivation and ROS scavenging. Therefore, CTS is a promising reagent against ROS-induced cardiomyopathy.

Myeloperoxidase and calprotectin; Any role as non-invasive markers for the prediction of ınflammation and fibrosis in non-alcoholic steatohepatitis?

BACKGROUND/AIMS

Specific serum markers reflecting hepatic inflammation and fibrosis are required to tailor the treatment strategies in non-alcoholic steatohepatitis (NASH). We aimed to investigate the roles of myeloperoxidase (MPO) and calprotectin in predicting the hepatic inflammation status and disease severity in NASH.

MATERIALS AND METHODS

A total of 48 patients with biopsy-proven NASH and 25 healthy volunteers with normal weight were prospectively enrolled. Serum MPO and calprotectin levels were compared between the NASH and control groups. Hepatic MPO and calprotectin expressions were compared in terms of histologic non-alcoholic fatty liver disease activity scores (NAS) (low NAS [≤4] vs. high NAS [>5]) and fibrosis stage (insignificant [F0-1]/significant [F2-4]).

RESULTS

Serum MPO and calprotectin levels were not significantly different between the NASH and control groups. In the subgroup analysis, hepatic MPO expression was significantly increased in patients with NASH with significant fibrosis than in those with insignificant fibrosis (F2-4: 7.04±3.61 vs. F0-1: 4.83±2.42, p=0.01). We found no difference between the groups with low and high NAS with regard to serum MPO and calprotectin levels and hepatic MPO and calprotectin expressions.

CONCLUSION

This study demonstrated that hepatic MPO expression can reflect advanced fibrosis in NASH. However, when serum MPO and calprotectin levels were evaluated as potential serum markers, both did not associate with hepatic inflammation status and fibrosis stage in NASH. Therefore, our study results preclude their use as serum markers for hepatic inflammation in NASH.

Does Hashimoto's Thyroiditis Increase the Risk of Cardiovascular Disease in Young Type 1 Diabetic Patients?

Background: Immunological and hormonal disorders have undoubted influence on the development of atherosclerotic process. Autoimmune diseases accompanying type 1 diabetes (T1D) may additionally accelerate atherosclerosis progression and increase the risk of cardiovascular events in the future. The influence of subclinical hypothyroidism on the cardiovascular system, in particular, has recently aroused great interest. The aim of our study was to assess intima-media thickness (cIMT) of common carotid arteries and the occurrence of classical atherosclerosis risk factors together with selected new biomarkers of cardiovascular diseases in young patients with type 1 diabetes mellitus coexisting with Hashimoto's disease (HD). Patients and Methods: The study included 50 adolescents and young adults with T1D with mean age 17.1 ± 3 years, with mean diabetes duration of 10.5 ± 3.3 years, including 20 patients with diagnosed HD: T1D and HD(+), and 30 patients with no additional diseases: T1D and HD(-). Twenty-two healthy, age-matched volunteers formed control group (C). We analyzed mean HbA₁c value from all years of disease, BMI, blood pressure, lipids, new biomarkers of atherosclerosis (hsCRP, adiponectin, myeloperoxidase, NT-proBNP peptide, vitamin D), and cIMT of common carotid arteries. Results: In the group of patients with T1D and HD(+), significantly higher BMI was found: 23.3 ± 4.4 vs. 21.28 ± 2.9 in group HD(-) and 19.65 ± 2.4 kg/m² in group C (p = 0.003), and higher waist circumference: 79 ± 10.9 vs. 75.10 ± 7.6 in group HD(-) vs. 69.0 ± 7.4 cm in group C (p < 0.001). The mean value of HbA₁c was higher in group T1D and HD(+): 8.8% than in group HD(-): 8.1% (p = 0.04). Significantly higher concentration of hsCRP and lower vitamin D were observed in T1D and HD(+) in comparison to T1D and HD(-) and the control group. The IMT index in the HD(+) group was 0.46 ± 0.05 mm and was comparable to the HD(-) group but significantly higher than in healthy controls: 0.41 ± 0.03 mm (P < 0.05). Conclusions: Young patients with type 1 diabetes mellitus and with coexisting Hashimoto's thyroiditis have a higher BMI, a higher waist circumference, and a higher HbA₁c value, which altogether may cause faster development of macroangiopathy in the near future. Additional risk for cardiovascular disease may result from low vitamin D and increased hsCRP concentration in this group of patients. Coexistence of Hashimoto's thyroiditis did not significantly affect the cIMT value in the studied population.

Oxidative Stress in Peripheral Arterial Disease (PAD) Mechanism and Biomarkers

Hemodynamic dysfunction mainly characterizes pathophysiology of peripheral arterial disease (PAD) leading to chronic ischemia. Hemodynamic dysfunction is the origin of intermittent claudication (chronic PAD) or of critical limb ischemia (very severe PAD). Notably, it is well known that oxidative stress (OxS) plays a pathophysiological role in PAD. The higher production of reactive oxygen species (ROS) from OxS and reduced redox capability are two crucial players in initiating and progressing PAD. A number of biomarkers highlight OxS and monitor it in PAD. The present review summarizes data on OxS, on biomarkers available to mark OxS occurrence and to monitor on PAD progression, as well as to evaluate the effects treatments in PAD patients. In conclusion, by detailing OxS and its biomarkers, we hope to encourage more studies to focus on drugs which combat OxS and inflammation.

Circulating Oxidative Stress Biomarkers in Clinical Studies on Type 2 Diabetes and Its Complications

Type 2 diabetes (T2DM) and its complications constitute a major worldwide public health problem, with high rates of morbidity and mortality. Biomarkers for predicting the occurrence and development of the disease may therefore offer benefits in terms of early diagnosis and intervention. This review provides an overview of human studies on circulating biomarkers of oxidative stress and antioxidant defence systems and discusses their usefulness from a clinical perspective. Most case-control studies documented an increase in biomarkers of oxidative lipid, protein, and nucleic acid damage in patients with prediabetes and in those with a diagnosis of T2DM compared to controls, and similar findings were reported in T2DM with micro- and macrovascular complications compared to those without. The inconsistence of the results regarding antioxidant defence systems renders difficulty to draw a general conclusion. The clinical relevance of biomarkers of oxidative lipid and protein damage for T2DM progression is uncertain, but prospective studies suggest that markers of oxidative nucleic acid damage such as 8-hydroxy-2'-deoxyguanosine and 8-hydroxyguanosine are promising for predicting macrovascular complications of T2DM. Emerging evidence also points out the relationship between serum PON1 and serum HO1 in T2DM and its complications. Overall, enhanced oxidative damage represents an underlying mechanism of glucose toxicity in T2DM and its related micro- and macrovascular complications suggesting that it may be considered as a potential additional target for pharmacotherapy. Therefore, further studies are needed to understand whether targeting oxidative stress may yield clinical benefits. In this view, the measurement of oxidative stress biomarkers in clinical trials deserves to be considered as an additional tool to currently used parameters to facilitate a more individualized treatment of T2DM in terms of drug choice and patient selection.

Markers of Atherosclerosis: Part 1 - Serological Markers

Atherosclerosis is a major contributor to morbidity and mortality worldwide. With therapeutic consequences in mind, several risk scores are being used to differentiate individuals with low, intermediate or high cardiovascular (CV) event risk. The most appropriate management of intermediate risk individuals is still not known, therefore, novel biomarkers are being sought to help re-stratify them as low or high risk. This narrative review is presented in two parts. Here, in Part 1, we summarise current knowledge on serum (serological) biomarkers of atherosclerosis. Among novel biomarkers, high sensitivity C-reactive protein (hsCRP) has emerged as the most promising in chronic situations, others need further clinical studies. However, it seems that a combination of serum biomarkers offers more to risk stratification than either biomarker alone. In Part 2, we address genetic and imaging markers of atherosclerosis, as well as other developments relevant to risk prediction.

Oxidative Stress in Aortas of Patients with Advanced Occlusive and Aneurysmal Diseases

BACKGROUND

Aortoiliac occlusive disease (AOD) and abdominal aortic aneurysm (AAA) are very important cardiovascular diseases that present different aspects of pathophysiology; however, oxidative stress and inflammatory response seem be relevant in both of them. Our objective was to evaluate oxidative damage and degree of inflammatory infiltrate in aortas of patients surgically treated for AOD and AAA.

MATERIALS AND METHODS

Levels of reactive oxygen species (ROS), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, and myeloperoxidase (MPO) expression as well as nitrite levels and superoxide dismutase (SOD) and catalase (CAT) activities were evaluated in aortas of patients with AOD (n = 16) or AAA (n = 14), while the control group was formed by cadaveric organ donors (n = 10). We also analyzed the degree of inflammatory infiltrate in these aortas.

RESULTS

There was an increase in ROS levels and NADPH oxidase activity in patients with AOD and AAA when compared with the control group, and the AOD group demonstrated higher ROS production and NADPH oxidase activity and also nitrite levels when compared with the AAA group (P < 0.001). On the other hand, an increase of SOD activity in the AOD group and CAT activity in the AAA group was observed. Inflammatory infiltrate and MPO expression were higher in the AOD group when compared with the control group (P < 0.05).

CONCLUSIONS

Oxidative stress is relevant in both AOD and AAA, though AOD presented higher ROS levels and NADPH activity. Increased activities of antioxidant enzymes may be a compensatory phenomenon which occurs in aortas of patients with AOD and AAA. Perhaps, a relationship between oxidative stress and degree of inflammatory infiltrate may exist in the pathophysiology of AOD and AAA.

Blood hydrogen peroxide break-down activity in healthy subjects and in patients at risk of cardiovascular events

BACKGROUND AND AIMS

Antioxidant status has been shown to be associated with cardiovascular events (CVEs). The aim of the study was to develop an assay measuring serum hydrogen peroxide (H₂O₂) break-down activity (HBA) of healthy subjects (HS) and to validate it in a cohort of patients with atrial fibrillation (AF).

METHODS

We developed the HBA assay in 121 HS and validated it in 842 AF patients. The occurrence of CVEs was registered and correlated with HBA in AF during a median follow-up of 30.6 months (3226 patient-years). A combined endpoint of CVEs included fatal/non-fatal ischemic stroke and myocardial infarction, cardiovascular death and transient ischemic attack.

RESULTS

In HS, median HBA was 61.2% [IQR: 52.9-69.4]. AF patients disclosed lower HBA than 30 HS balanced for age and sex (48.6% [IQR: 24.7-65.1] vs. 59.4% [IQR: 49.2-66.2], p < 0.001). During a mean follow-up of 30.6 months (3226 patient-years), 168 CVEs occurred (5.2%/year). A multivariable Cox's proportional hazards regression analysis showed that age group 3 (71-80 years, HR:5.419, p = 0.020), age group 4 (>80 years, HR:9.783, p = 0.002), diabetes (HR:1.464, p = 0.049), previous cardiac events (HR:1.887, p = 0.001) and HBA (below median, HR:2.313, p < 0.001) predicted CVEs.

CONCLUSIONS

We developed an easy assay to measure serum HBA, which was associated with CVEs in AF patients. This assay may represent an additional useful tool for cardiovascular risk stratification and should be validated in other high-risk populations.

Uric Acid Impairs Insulin Signaling by Promoting Enpp1 Binding to Insulin Receptor in Human Umbilical Vein Endothelial Cells

High levels of uric acid (UA) are associated with type-2 diabetes and cardiovascular disease. Recent pieces of evidence attributed to UA a causative role in the appearance of diabetes and vascular damage. However, the molecular mechanisms by which UA induces these alterations have not been completely elucidated so far. Among the mechanisms underlying insulin resistance, it was reported the role of a transmembrane glycoprotein, named either ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) or plasma cell antigen 1, which is able to inhibit the function of insulin receptor (I_R) and it is overexpressed in insulin-resistant subjects. In keeping with this, we stimulated human umbilical vein endothelial cells (HUVECs) with insulin and UA to investigate the effects of UA on insulin signaling pathway, testing the hypothesis that UA can interfere with insulin signaling by the activation of ENPP1. Cultures of HUVECs were stimulated with insulin, UA and the urate transporter SLC22A12 (URAT1) inhibitor probenecid. Akt and endothelial nitric oxide synthase (eNOS) phosphorylation levels were investigated by immunoblotting. ENPP1 binding to I_R and its tyrosine phosphorylation levels were tested by immunoprecipitation and immunoblotting. UA inhibited insulin-induced Akt/eNOS axis. Moreover, UA induced ENPP1 binding to I_R that resulted in an impairment of insulin signaling cascade. Probenecid reverted UA effects, suggesting that UA intracellular uptake is required for its action. In endothelial cells, UA directly interferes with insulin signaling pathway at receptor level, through ENPP1 recruitment. This evidence suggests a new molecular model of UA-induced insulin resistance and vascular damage.

Unraveling mechanisms of toxicant-induced oxidative stress in cardiovascular disease

To date, numerous clinical studies examining correlations between oxidative stress biomarkers and cardiovascular diseases (CVD) have repeatedly suggested a role for oxidant injury in the pathogenesis of diseases such as atherosclerosis. Despite this, antioxidant supplementation trials have not demonstrated a reduction in disease progression. Nevertheless, small animal and epidemiological studies have linked exposures to certain toxicants with increased CVD risk involving putative oxidative stress mechanisms. A few prototypical vascular toxicants will be discussed as examples of toxicants that likely act via oxidative stress mechanisms. For discussion, we will classify these toxicants as those that induce direct (e.g., arsenic, nucleoside reverse transcriptase inhibitors) versus indirect (particulate matter, ozone) oxidative stress mechanisms, and those that likely induce CVD through both direct and indirect mechanisms (cigarette smoke). Finally, new findings in oxidative stress research, including the emerging importance of reactive sulfur species, hydrogen peroxide as a presumed endothelium-derived hyperpolarizing factors, etc., will be discussed, as well as the need to determine the role of toxicants in modulating these newly identified pathways. Moreover, given the lack of success in conclusively demonstrating the roles of oxidative stress in CVD risk stratification, research probing the roles of toxicant exposures in propagating CVD pathogenesis may be a novel approach for more conclusively delineating the causal role of oxidative stress in CVD initiation and progression.

Antioxidant and Antihyperlipidemic Effects of Campomanesia adamantium O. Berg Root

Campomanesia adamantium O. Berg, popularly known as guavira, has been used in Brazilian traditional medicine for reduction of serum lipid. The present study was carried out to investigate the antioxidant and antihyperlipidemic effects of Campomanesia adamantium root aqueous extract (ExCA). Phenolic compounds were quantified in the ExCA and gallic and ellagic acids were identified by HPLC. ExCA showed efficiency in 2,2-diphenyl-1-picrylhydrazyl free radical scavenging, with IC₅₀ similar to butylhydroxytoluene control, and protected the erythrocytes against lipid peroxidation induced by 2,2′-azobis(2-methylpropionamidine) dihydrochloride, reducing generated malondialdehyde. Hyperlipidemic Wistar rats treated daily by gavage during eight weeks with ExCA (200 mg/kg of body weight) showed reduced serum level of total cholesterol and triglycerides, similar to normolipidemic rats and hyperlipidemic rats treated with simvastatin (30 mg/kg of body weight) and ciprofibrate (2 mg/kg of body weight). Moreover, the treatment with ExCA also decreased malondialdehyde serum level in the hyperlipidemic rats. The body weight and organ mass were unmodified by ExCA in hyperlipidemic rats, except an increase of liver mass; however, the hepatic enzymes, alanine aminotransferase and aspartate aminotransferase, were unchanged. Together, these results confirm the potential value of Campomanesia adamantium root for lowering lipid peroxidation and lipid serum level, improving risk factors for cardiometabolic diseases development.

Circulating miR-130a, miR-27b, and miR-210 in Patients With Peripheral Artery Disease and Their Potential Relationship With Oxidative Stress

Some emerging risk factors such as oxidative stress biomarkers and microRNAs (miRs) may add additional value to the established risk factors for peripheral artery disease (PAD). We enrolled 27 patients with PAD and 27 age-matched controls. We examined the levels of a series of miRs (miR-130a, miR-27b, and miR-210) in serum samples. The level of well-established oxidative stress biomarkers, such as lipid hydroperoxides, isoprostanes, hemeoxygenase-1 (HO-1) and reduced glutathione, was also measured in plasma and their relationship with the miRs was determined. Levels of miR-130a, miR-27b, and miR-210 were significantly increased in patients with PAD when compared to the controls. The level of miR-130 was positively correlated with body mass index, whereas miR-210 was inversely associated with pain-free walking distance (PfWD). None of the evaluated miRs was associated with lowered PfWD of patients with PAD (stage IIa > 250 m, IIb < 250 m) or oxidative stress parameters. In conclusion, our findings suggest the need for more research to assess if miRs can serve as useful markers for the early diagnosis and monitoring of PAD.

RETRACTED:Betulinic acid downregulates expression of oxidative stress-induced lipoprotein lipase via the PKC/ERK/c-Fos pathway in RAW264.7 macrophages

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. Concerns raised by Dr. Sander Kersten in PubPeer pointed out that Figures 6.1B and 6.2B of this paper were different figures but the legends and Western blots were identical; the quantification was also seen to be different between the two figures. Shortly afterwards, the authors asked to publish a corrigendum for part B of Figure 6.1, including images of western blots and associated bar plots. Subsequently, the journal conducted an investigation and found evidence that there had been improper manipulation and duplication of images in Figures 2 E, 6.2 B, 5 A and and 6.2 D, as shown by the reuse of several western blot bands with approximately 180° rotation in each case. After raising the complaint with the authors, the corresponding author agreed that the paper should be retracted. The authors apologise to the readers of the journal.

Salivary Lipid Peroxidation in Patients With Generalized Chronic Periodontitis and Acute Coronary Syndrome

BACKGROUND

Lipid peroxidation is a major consequence of oxidative stress and can be evaluated via malondialdehyde (MDA) levels. The present study aims to assess MDA levels in the saliva of patients with chronic periodontitis (CP) and acute coronary syndrome (ACS) and establish their correlation with periodontal clinical parameters, serum high-sensitivity C-reactive protein (hsCRP), and plasma fibrinogen.

METHODS

The study enrolled 64 patients stratified into four age- and sex-matched groups: both ACS and CP, ACS only, CP only, and healthy controls. All patients were examined, periodontal clinical parameters were recorded, and saliva and blood samples were collected. Salivary MDA levels were measured using a spectrophotometric assay. A quantitative turbidimetric test was used for the measurement of serum hsCRP levels, and plasma fibrinogen levels were determined using an automated analyzer.

RESULTS

Salivary MDA levels were significantly higher in patients with both ACS and CP than in those with only ACS or only CP and healthy controls (P <0.05). There were significant positive correlations between salivary MDA levels and periodontal clinical parameters as well as biomarkers for cardiovascular events (P <0.001).

CONCLUSIONS

To our knowledge, this study is the first to investigate salivary MDA levels in patients with ACS and their correlations with serum hsCRP and plasma fibrinogen levels. The results indicate that salivary MDA levels could be a biomarker for cardiovascular and/or periodontal disease.

Extra virgin olive oil use is associated with improved post-prandial blood glucose and LDL cholesterol in healthy subjects

OBJECTIVES

Extra virgin olive oil (EVOO) is a key component of the Mediterranean diet and seems to account for the protective effect against cardiovascular disease. However, the underlying mechanism is still elusive.

DESIGN

We tested the effect of EVOO, added to Mediterranean-type meal, on post-prandial glycemic and lipid profile.

SUBJECTS

Post-prandial glycemic and lipid profile were investigated in 25 healthy subjects who were randomly allocated in a cross-over design to a Mediterranean-type meal added with or without 10 g EVOO (first study), or Mediterranean-type meal with EVOO (10 g) or corn oil (10 g; second study). Glycemic profile, which included glucose, insulin, dipeptidyl-peptidase-4 (DPP-4) protein and activity, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and lipid profile, which included, low-density lipoprotein (LDL) cholesterol (LDL-C), oxidized LDL (ox-LDL), triglycerides and high-density lipoprotein (HDL) cholesterol (HDL-C), were analyzed before and 2 h after the meal.

RESULTS

In the first study, 2 h after meal, subjects who assumed a meal with EVOO had significantly lower blood glucose (P<0.001), DPP-4 protein (P<0.001) and activity (P<0.001), LDL-C (P<0.001) and ox-LDL (P<0.001) and higher insulin (P<0.05), GLP-1 (P<0.001) and GIP (P<0.05) compared with those without EVOO. The second study showed that compared with corn oil, EVOO improved both glycemic and lipid profile. Thus, a significantly smaller increase of glucose (P<0.05), DPP4 protein (P<0.001) and activity (P<0.05) and higher increase of insulin (P<0.001) and GLP-1 (P<0.001) were observed. Furthermore, compared with corn oil, EVOO showed a significantly less increase of LDL-C (P<0.05) and ox-LDL (P<0.001).

CONCLUSIONS

We report for the first time that EVOO improves post-prandial glucose and LDL-C, an effect that may account for the antiatherosclerotic effect of the Mediterranean diet.

Flaxseed Oil Containing α -Linolenic Acid Ester of Plant Sterol Improved Atherosclerosis in ApoE Deficient Mice

Plant sterols (PS) have potential preventive function in atherosclerosis due to their cholesterol-lowering ability. Dietary α-linolenic acid in flaxseed oil is associated with a reduction in cardiovascular events through its hypolipidemic and anti-inflammation properties. This study was designed to evaluate the effects of flaxseed oil containing α-linolenic acid ester of PS (ALA-PS) on atherosclerosis and investigate the underlying mechanisms. C57BL/6 mice were administered a regular diet and apoE knockout (apoE-KO) mice were given a high fat diet alone or supplemented with 5% flaxseed oil with or without 3.3% ALA-PS for 18 weeks. Results demonstrated that flaxseed oil containing ALA-PS was synergistically interaction in ameliorating atherosclerosis as well as optimizing overall lipid levels, inhibiting inflammation and reducing oxidative stress. These data were associated with the modification effects on expression levels of genes involved in lipid metabolism (PPARα, HMGCR, and SREBPs), inflammation (IL-6, TNF, MCP-1, and VCAM-1), and oxidative stress (NADPH oxidase).

Hydrogen Peroxide Induce Human Cytomegalovirus Replication through the Activation of p38-MAPK Signaling Pathway

Human cytomegalovirus (HCMV) is a major risk factor in transplantation and AIDS patients, which induces high morbidity and mortality. These patients infected with HCMV experience an imbalance of redox homeostasis that cause accumulation of reactive oxygen species (ROS) at the cellular level. H₂O₂, the most common reactive oxygen species, is the main byproduct of oxidative metabolism. However, the function of H₂O₂ on HCMV infection is not yet fully understood and the effect and mechanism of N-acetylcysteine (NAC) on H₂O₂-stimulated HCMV replication is unclear. We, therefore, examined the effect of NAC on H₂O₂-induced HCMV production in human foreskin fibroblast cells. In the present study, we found that H₂O₂ enhanced HCMV lytic replication through promoting major immediate early (MIE) promoter activity and immediate early (IE) gene transcription. Conversely, NAC inhibited H₂O₂-upregulated viral IE gene expression and viral replication. The suppressive effect of NAC on CMV in an acute CMV-infected mouse model also showed a relationship between antioxidants and viral lytic replication. Intriguingly, the enhancement of HCMV replication via supplementation with H₂O₂ was accompanied with the activation of the p38 mitogen-activated protein kinase pathway. Similar to NAC, the p38 inhibitor SB203580 inhibited H₂O₂-induced p38 phosphorylation and HCMV upregulation, while upregulation of inducible ROS was unaffected. These results directly relate HCMV replication to H₂O₂, suggesting that treatment with antioxidants may be an attractive preventive and therapeutic strategy for HCMV.

Mechanisms And Management Of Thrombo-Embolism In Atrial Fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia in the general population and in patients with a history of cardiovascular disease. AF is becoming an outbreak particularly for the western countries as it increases with advancing age; furthermore, AF has a negative social impact because it is associated with stroke and myocardial infarction. Thrombosis generated in the left atrial appendage with ensuing embolism in the cerebral circulation is considered the most important cause of ischemic stroke. In addition to thrombo-embolism, AF is characterized by a constellation of atherosclerotic risk factors, including hypertension, dyslipidaemia and diabetes, which may predispose to serious clinical complications of atherosclerosis such myocardial infarction. Even if interventional trials with oral anticoagulants such as warfarin reduced by about 60% the risk of stroke, AF patients still disclose an elevated residual cardiovascular risk, which may severely complicate the clinical course and management of AF. Recent trials with new oral anticoagulants (NOACs) are opening a new scenario for the treatment of AF, which could improve its management, as NOACs apparently would not require monitoring. However, important caveats are emerging in the real world of AF management, which are questioning the concept that NOACs do not need monitoring. Thus, issues related to compliance and large variability in blood concentration may negatively influence the cost/effectiveness benefit of NOACs. This review will focus on pathophysiology of thrombo-embolism and athero-thrombosis and the impact of old and new anticoagulants in the real world of AF management.

Inhibition of cellular methyltransferases promotes endothelial cell activation by suppressing glutathione peroxidase 1 protein expression

S-adenosylhomocysteine (SAH) is a negative regulator of most methyltransferases and the precursor for the cardiovascular risk factor homocysteine. We have previously identified a link between the homocysteine-induced suppression of the selenoprotein glutathione peroxidase 1 (GPx-1) and endothelial dysfunction. Here we demonstrate a specific mechanism by which hypomethylation, promoted by the accumulation of the homocysteine precursor SAH, suppresses GPx-1 expression and leads to inflammatory activation of endothelial cells. The expression of GPx-1 and a subset of other selenoproteins is dependent on the methylation of the tRNA(Sec) to the Um34 form. The formation of methylated tRNA(Sec) facilitates translational incorporation of selenocysteine at a UGA codon. Our findings demonstrate that SAH accumulation in endothelial cells suppresses the expression of GPx-1 to promote oxidative stress. Hypomethylation stress, caused by SAH accumulation, inhibits the formation of the methylated isoform of the tRNA(Sec) and reduces GPx-1 expression. In contrast, under these conditions, the expression and activity of thioredoxin reductase 1, another selenoprotein, is increased. Furthermore, SAH-induced oxidative stress creates a proinflammatory activation of endothelial cells characterized by up-regulation of adhesion molecules and an augmented capacity to bind leukocytes. Taken together, these data suggest that SAH accumulation in endothelial cells can induce tRNA(Sec) hypomethylation, which alters the expression of selenoproteins such as GPx-1 to contribute to a proatherogenic endothelial phenotype.

Propolis Reduces Phosphatidylcholine-Specific Phospholipase C Activity and Increases Annexin a7 Level in Oxidized-LDL-Stimulated Human Umbilical Vein Endothelial Cells

To understand the mechanisms underlying the regulating dyslipidemia action of Chinese propolis and Brazilian green propolis, we investigated their effects on phosphatidylcholine-specific phospholipase C (PC-PLC) activity and annexin a7 (ANXA7) level which play crucial roles in the control of the progress of atherosclerosis. Furthermore, active oxygen species (ROS) levels, nuclear factor-KappaB p65 (NF-κB p65), and mitochondrial membrane potential (MMP) were also investigated in oxidized-LDL- (ox-LDL-) stimulated human umbilical vein endothelial cells (HUVECs). Our data indicated that the treatment of both types of propolis 12.5 μg/mL significantly increased cell viability and attenuated apoptosis rate, increased ANXA7 level, and decreased PC-PLC activity. Both types of propolis also inhibited ROS generation as well as the subsequent MMP collapse, and NF-κB p65 activation induced by ox-LDL in HUVECs. Our results also indicated that Chinese propolis and Brazilian green propolis had similar biological activities and prevented ox-LDL induced cellular dysfunction in HUVECs.