Clinical impact of admission urinary 8-hydroxydeoxyguanosine level for predicting cardiovascular mortality in patients with acute coronary syndrome

The Dual Role of Oxidative Stress in Atherosclerosis and Coronary Artery Disease: Pathological Mechanisms and Diagnostic Potential

Oxidative stress plays a pivotal role in the pathogenesis of atherosclerosis and coronary artery disease (CAD), with both beneficial and detrimental effects on cardiovascular health. On one hand, the excessive production of reactive oxygen species (ROS) contributes to endothelial dysfunction, inflammation, and vascular remodeling, which are central to the development and progression of CAD. These pathological effects drive key processes such as atherosclerosis, plaque formation, and thrombosis. On the other hand, moderate levels of oxidative stress can have beneficial effects on cardiovascular health. These include regulating vascular tone by promoting blood vessel dilation, supporting endothelial function through nitric oxide production, and enhancing the immune response to prevent infections. Additionally, oxidative stress can stimulate cellular adaptation to stress, promote cell survival, and encourage angiogenesis, which helps form new blood vessels to improve blood flow. Oxidative stress also holds promise as a source of biomarkers that could aid in the diagnosis, prognosis, and monitoring of CAD. Specific oxidative markers, such as malondialdehyde (MDA), isoprostanes (isoP), ischemia-modified albumin, and antioxidant enzyme activity, have been identified as potential indicators of disease severity and therapeutic response. This review explores the dual nature of oxidative stress in atherosclerosis and CAD, examining its mechanisms in disease pathogenesis as well as its emerging role in clinical diagnostics and targeted therapies. The future directions for research aimed at harnessing the diagnostic and therapeutic potential of oxidative stress biomarkers are also discussed. Understanding the balance between the detrimental and beneficial effects of oxidative stress could lead to innovative approaches in the prevention and management of CAD.

The role of DNA and RNA guanosine oxidation in cardiovascular diseases

Cardiovascular diseases (CVD) persist as a prominent cause of mortality worldwide, with oxidative stress constituting a pivotal contributory element. The oxidative modification of guanosine, specifically 8-oxoguanine, has emerged as a crucial biomarker for oxidative stress, providing novel insights into the molecular underpinnings of CVD. 8-Oxoguanine can be directly generated at the DNA (8-oxo-dG) and RNA (8-oxo-G) levels, as well as at the free nucleotide level (8-oxo-dGTP or 8-oxo-GTP), which are produced and can be integrated through DNA replication or RNA transcription. When exposed to oxidative stress, guanine is more readily produced in RNA than in DNA. A burgeoning body of research surrounds 8-oxoguanine, exhibits its accumulation playing a pivotal role in the development of CVD. Therapeutic approaches targeting oxidative 8-Oxoguanine damage to DNA and RNA, encompassing the modulation of repair enzymes and the development of small molecule inhibitors, are anticipated to enhance CVD management. In conclusion, we explore the noteworthy elevation of 8-oxoguanine levels in patients with various cardiac conditions and deliberate upon the formation and regulation of 8-oxo-dG and 8-oxo-G under oxidative stress, as well as their function in CVD.

Prognostic importance of glycemic variability on left ventricular reverse remodeling after the first episode of ST-segment elevation myocardial infarction

BACKGROUND

This study aimed to investigate the effect of glycemic variability (GV), determined using a continuous glucose monitoring system (CGMS), on left ventricular reverse remodeling (LVRR) after ST-segment elevation myocardial infarction (STEMI).

METHODS

A total of 201 consecutive patients with STEMI who underwent reperfusion therapy within 12 h of onset were enrolled. GV was measured using a CGMS and determined as the mean amplitude of glycemic excursion (MAGE). Left ventricular volumetric parameters were measured using cardiac magnetic resonance imaging (CMRI). LVRR was defined as an absolute decrease in the LV end-systolic volume index of > 10% from 1 week to 7 months after admission. Associations were also examined between GV and LVRR and between LVRR and the incidence of major adverse cardiovascular events (MACE; cardiovascular death, acute coronary syndrome recurrence, non-fatal stroke, and heart failure hospitalization).

RESULTS

The prevalence of LVRR was 28% (n = 57). The MAGE was independent predictor of LVRR (odds ratio [OR] 0.98, p = 0.002). Twenty patients experienced MACE during the follow-up period (median, 65 months). The incidence of MACE was lower in patients with LVRR than in those without (2% vs. 13%, p = 0.016).

CONCLUSION

Low GV, determined using a CGMS, was significantly associated with LVRR, which might lead to a good prognosis. Further studies are needed to validate the importance of GV in LVRR in patients with STEMI.

Emerging Biomarkers for Predicting Clinical Outcomes in Patients with Heart Disease

Cardiovascular disease is most frequently caused by the development and progression of atherosclerosis. When coronary arteries are afflicted, and the stenoses caused by atherosclerotic plaques are severe enough, the metabolic supply-and-offer balance is disturbed, leading to myocardial ischemia. If atherosclerotic plaques become unstable and local thrombosis develops, a myocardial infarction occurs. Sometimes, myocardial ischemia and infarction may result in significant and irreversible heart failure. To prevent severe complications, such as acute coronary syndromes and ischemia-related heart failure, extensive efforts have been made for developing biomarkers that would help identify patients at increased risk for cardiovascular events. In this two-part study, we attempted to provide a review of existing knowledge of blood biomarkers that may be used in this setting. The first part of this work was dedicated to conventional biomarkers, which are already used in clinical practice. In the second part, here presented, we discuss emerging biomarkers which have not yet become mainstream.

Oxidative stress-responsive apoptosis-inducing protein in patients with heterozygous familial hypercholesterolemia

Oxidative stress, an inducer of apoptosis, plays a critical role in ischemia/reperfusion injury and atherosclerosis. We previously identified an apoptosis-inducing ligand, the post-translationally modified secreted form of eukaryotic translation initiation factor 5A (eIF5A), 'oxidative stress-responsive apoptosis-inducing protein' (ORAIP). In this study, we investigated the role of ORAIP in patients with heterozygous familial hypercholesterolemia (HeFH), a leading cause of premature cardiovascular disease. We analyzed plasma ORAIP and oxidized low-density lipoprotein (oxLDL) levels in 60 patients with HeFH (60% male, 57.0 ± 13.6 years of age) and 20 patients with LDL-C hypercholesterolemia (DL, 85% male, 64.1 ± 13.3 years of age). The coronary artery atherosclerosis from the patients with HeFH who had a coronary artery bypass graft was investigated by double immunostaining. The plasma ORAIP levels in the patients with HeFH were significantly elevated compared to those in the patients with DL (73.5 ± 46.0 vs. 48.3 ± 21.4 ng/mL, p = 0.0277). The plasma oxLDL levels in HeFH patients were also elevated (156.8 ± 65.2 vs. 123.7 ± 46.6 mg/dL, p = 0.0461) compared to those in DL patients and correlated with maxLDL-C levels (R = 0.4454, p = 0.00648). Double-immunostaining of ORAIP and oxLDL in the coronary artery from patients with HeFH who had a coronary artery bypass graft showed that ORAIP and oxLDL were colocalized with apoptotic vascular smooth muscle cells in the atherosclerotic plaque. ORAIP plays a role in the development of oxidative stress-induced atherosclerosis and may be an important therapeutic target for plaque rupture in patients with HeFH.

Molecular characterization of two Chinese pedigrees with maternally inherited hypertension

BACKGROUND

Mutations in mitochondrial tRNA (mt-tRNA) genes are associated with hypertension, although their pathogenic mechanisms remain poorly understood.

METHODS

In the present study, two Han Chinese families with maternally transmitted hypertension were interviewed. The mtDNA mutations of matrilineal relatives were screened by polymerase chain reaction-Sanger sequencing. Mitochondrial ATP, membrane potential and reactive oxygen species (ROS) were also analyzed in polymononuclear leukocytes carrying these mt-tRNA mutations. Additionally, the levels of oxidative stress-related biomarkers [malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and 8-hydroxy-2-deoxyguanosine (8-OHdG)] were analyzed.

RESULTS

Nine of 13 adult matrilineal relatives of these pedigrees exhibited a wide range of severity of hypertension. The age at onset of hypertension was 30-62 years (average 46 years). Mutational screening of mitochondrial genomes revealed tRNA^Arg T10410C and T10454C mutations. Indeed, the m.T10454C and m.T10410C mutations occurred at conserved bases of TΨC-loop and acceptor arm of tRNA^Arg (positions 55 and 6), which are critical for tRNA^Arg post-transcriptional modification. Thus, the defects in tRNA modification may cause failure in tRNA metabolism, impairing mitochondrial translation. Biochemical analysis revealed that m.T10454C or m.T10410C mutation significantly reduced mitochondrial ATP and membrane potential and also increased ROS production in mutant cell lines (all p < 0.05). In addition, the levels of MDA and 8-OHdG in hypertensive patients markedly increased, whereas those of SOD and GSH-Px decreased (all p < 0.05).

CONCLUSIONS

These findings demonstrate that m.T10410C and m.T10454C mutations affect the structure and function of tRNA^Arg and consequently alter mitochondrial function and lead to oxidative stress, which are involved in the pathogenesis of maternally inherited hypertension.

Skeletal muscle mass is associated with glycemic variability in patients with ST-segment elevation myocardial infarction

Skeletal muscle function has been studied to determine its effect on glucose metabolism; however, its effect on glycemic variability (GV), which is a significant glycemic marker in patients with coronary artery disease, is unknown. The aim of the present study was to elucidate the association between skeletal muscle mass and GV. Two hundred and eight consecutive ST-segment elevation myocardial infarction (STEMI) patients who underwent continuous glucose monitoring to evaluate mean amplitude of glycemic excursion (MAGE) as GV and a dual-energy X-ray absorptiometry (DEXA) to evaluate skeletal muscle mass were enrolled. Skeletal muscle index (SMI) level was calculated as skeletal muscle mass divided by height squared (kg/m²). SMI level in men had a weak inverse correlation with Log MAGE level by the linear regression model in diabetes mellitus (DM) patients (R² = 0.139, P = 0.004) and even in non-DM patients (R² = 0.068, P = 0.004). Multivariate linear regression analysis with a stepwise algorithm (age, male sex, body mass index [BMI], hemoglobin A1c [HbA1c], fasting glucose, HOMA-IR, and SMI; R² = 0.203, P < 0.001) demonstrated that HbA1c level (B = 0.077, P < 0.001) and SMI level (B = - 0.062, P < 0.001) were both independently associated with Log MAGE level. This association was also confirmed in limited non-DM patients with a subgroup analysis. SMI level was associated with Log MAGE level (B = - 0.055, P = 0.001) independent of BMI or HbA1c level. SMI level was inversely associated with MAGE level independent of glucose metabolism in STEMI patients, suggesting the significance of skeletal muscle mass as blood glucose storage for glucose homeostasis to reduce GV.