Polymorphisms of C242T and A640G in CYBA gene and the risk of coronary artery disease: a meta-analysis

Analysis of Genes Involved in Oxidative Stress and Iron Metabolism in Heart Failure: A Step Forward in Risk Stratification

INTRODUCTION

Heart failure (HF) is a clinical syndrome characterized by cardinal symptoms that may be accompanied by signs. It results from structural and/or functional abnormalities of the heart leading to elevated intracardiac pressures and/or inadequate cardiac output at rest and/or during exercise. The prevalence of iron deficiency and anemia justifies the current guidelines recommendation of screening. Genes HP, ACE, MTHFR, HFE, and CYBA are involved in oxidative mechanisms, iron metabolism, and hematologic homeostasis. This study investigates the contribution of variants Hp1/2 (HP), I/D (ACE), C677T (MTHFR), C282Y and H63D (HFE), and C242T (CYBA) to the development of HF, either independently or in epistasis.

METHODS

We used a database of 389 individuals, 143 HF patients, and 246 healthy controls. Genotypes were characterized through PAGE electrophoresis, PCR, PCR-RFLP, and multiplex-ARMS. Data analysis was performed with the SPSS® 26.0 software (IBM Corp., Armonk, NY).

RESULTS

We observed a significant association between the MTHFR gene and HF predisposition. The presence of allele T and genotype CT constituted risk, while genotype CC granted protection. Epistatic interactions revealed risk between genotype II of the ACE gene and genotypes CC (C282Y) or HH (H63D) of the HFE gene. Risk was also observed for interactions between genotype CC (CYBA)and genotypes 2-2 (HP), CT (MTHFR), or HH (HFE-H63D).

CONCLUSION

We concluded that genes HP, ACE, MTHFR, HFE, and CYBA contribute to the susceptibility for HF, individually or in epistasis. This study contributes to the clarification of the role that genes involved in oxidative mechanisms and iron metabolism play in the physiopathology of HF. It is, therefore, a step forward in risk stratification and personalized medicine.

Myeloperoxidase G-463A and CYBA C242T genetic variants in gestational diabetes mellitus

Oxidative stress plays an important role in the pathophysiology of gestational diabetes mellitus (GDM). We investigated the relationship between NADPH oxidase p22phox subunit (CYBA) C242T (rs4673) and myeloperoxidase (MPO) G-463A (rs2333227) genetic variants and GDM in 719 patients with GDM and 1205 control women. Clinical, metabolic, and oxidative stress parameters were analyzed. We found that frequencies of the A allele (15.6% vs 12.3%) and GA + AA genotype (28.5% vs 23.2%) of the MPO G-463A variation were significantly higher in patients with GDM than in the control women (OR = 1.318, 95% CI: 1.068-1.625, P = 0.010 for the dominant model; OR = 1.999, 95% CI: 1.040-3.843, P = 0.034 for the recessive model; OR = 1.320, 95% CI: 1.095-1.591, P = 0.004 for the allele model). Genotype GA + AA remained a significant predictor of GDM in a logistic regression model including age and BMI at delivery (OR = 1.282, 95% CI: 1.037‒1.583, P = 0.021). Furthermore, the ‒463A allele was associated with higher TG and the 242T allele was related to higher pre-pregnancy BMI and oxidative stress index in all subjects (P < 0.05). The 242T allele was also associated with higher homeostatic model assessment of insulin resistance but lower serum total antioxidant capacity in patients with GDM (P < 0.05). We conclude that the MPO G-463A, but not the CYBA C242T, genetic variation is associated with an increased risk of GDM in Chinese women. These two genetic polymorphisms may be linked to obesity, dyslipidemia, insulin resistance, and oxidative stress.

Interpretation of Dihydrorhodamine-1,2,3 Flow Cytometry in Chronic Granulomatous Disease: an Atypical Exemplar

PURPOSE

This is a functional characterization of a novel CYBA variant associated with normal DHR flow cytometry. Chronic granulomatous disease (CGD) is an inborn error of immunity characterized by recurrent bacterial and fungal infections and dysregulated inflammatory responses due to defective phagocytic cell function leading to the formation of granulomas. CGD patients have pathogenic variants in any of the five components of the phagocytic NADPH oxidase, which transfers electrons through the phagosomal membrane and produces superoxide upon bacterial uptake. Here, we report a pediatric female patient with a novel homozygous missense variant (c.293C > T, p.(Ser98Leu)) in CYBA, encoding the p22^phox protein, associated with autosomal recessive CGD.

METHODS AND RESULTS

The patient presented with severe recurrent pneumonia. Specific pathogens identified included Burkholderia and Serratia species suggesting neutrophil functional abnormalities; however, the dihydrorhodamine-1,2,3 (DHR) flow cytometric and cytochrome c reduction assays for neutrophil respiratory burst fell within the low side of the normal range. Western blot and flow cytometric analysis of individual NADPH oxidase components revealed reduced levels of p22^phox and gp91^phoxphox proteins. The pathological consequence of the p.Ser98Leu variant was further evaluated in heterologous expression systems, which confirmed reduced p22^phox protein stability and oxidase activity.

CONCLUSIONS

Although this patient did not exhibit all the classic features of CGD, such as granulomas and skin infections, she had recurrent pneumonias with oxidant-sensitive pathognomonic organisms, resulting in appropriate targeted CGD testing. This case emphasizes the need to contextually interpret laboratory data, especially using clinical findings to direct additional assessments including genetic analysis.

Cytochrome b-245 Alpha Chain Gene Variants and Arterial Function in Indonesian Short Stature Children

Background

The association between short stature, undernutrition and the risk to cardiovascular disease has been clinically established. Genetic factor, particularly the variants in cytochrome b-245 alpha chain (CYBA) gene, which alter the formation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase level, might affect arterial function. This study aimed to observe the association between single nucleotide variants (SNVs) of the CYBA gene and the arterial function of short stature children to understand the reason why some people with short stature develop cardiovascular disease.

Methods

A total of 142 genomic deoxyribonucleic acid (DNA) samples have been collected from short stature children in Brebes, Central Java, Indonesia. Four common single-nucleotide polymorphisms (SNPs): C242T (rs4673), A640G (rs1049255), -930A>G (rs9932581) and *49A>G (rs7195830) in the CYBA gene were examined using TaqMan allelic discrimination assay. The arterial function was measured using transthoracic echocardiography and described as aortic stiffness and distensibility index. Statistical analysis was done to find a significant difference in arterial function between genotypes of each SNV.

Results

A P-value of < 0.05 was considered significant. In rs9932581 (-930A>G) of CYBA gene, the subjects with GG genotype were found to have significantly lower arterial stiffness and higher distensibility compared to AA and AG genotypes. No significant difference was found in the other SNVs.

Conclusion

The GG genotype in rs9932581 of the CYBA gene might have a protective effect on cardiovascular disease in short stature children.

Mitochondrion as a Selective Target for the Treatment of Atherosclerosis: Role of Mitochondrial DNA Mutations and Defective Mitophagy in the Pathogenesis of Atherosclerosis and Chronic Inflammation

BACKGROUND

Atherosclerosis is a chronic inflammatory condition that affects different arteries in the human body and often leads to severe neurological complications, such as stroke and its sequelae. Affected blood vessels develop atherosclerotic lesions in the form of focal thickening of the intimal layer, so called atherosclerotic plaques.

OBJECTIVES

Despite the high priority of atherosclerosis research for global health and the numerous preclinical and clinical studies conducted, currently, there is no effective pharmacological treatment that directly impacts atherosclerotic plaques. Many knowledge gaps exist in our understanding of the mechanisms of plaque formation. In this review, we discuss the role of mitochondria in different cell types involved in atherogenesis and provide information about mtDNA mutations associated with the disease.

RESULTS

Mitochondria of blood and arterial wall cells appear to be one of the important factors in disease initiation and development. Significant experimental evidence connects oxidative stress associated with mitochondrial dysfunction and vascular disease. Moreover, mitochondrial DNA (mtDNA) deletions and mutations are being considered as potential disease markers. Further study of mtDNA damage and associated dysfunction may open new perspectives for atherosclerosis treatment.

CONCLUSION

Mitochondria can be considered as important disease-modifying factors in several chronic pathologies. Deletions and mutations of mtDNA may be used as potential disease markers. Mitochondria-targeting antioxidant therapies appear to be promising for the development of treatment of atherosclerosis and other diseases associated with oxidative stress and chronic inflammation.

[Association of AGT, ACE, NOS3, TNF, MMP9, CYBA polymorphism with subclinical arterial wall changes]

Aim    Activation of the renin-angiotensin-aldosterone system, decreased nitric oxide production, chronic inflammation, and oxidative stress result in subclinical changes in the arterial wall, which favor the development of cardiovascular diseases (CVD). The effect of allelic gene variants that encode the proteins participating in pathogenetic pathways of age-associated diseases with subclinical changes in the arterial wall [increased pulse wave velocity (PWV), increased intima-media thickness, endothelial dysfunction (ED), presence of atherosclerotic plaques (ASP)] are understudied. This study analyzed the relationship between AGT, ACE, NOS3 TNF, MMP9, and CYBA gene polymorphism and the presence of subclinical changes in the arterial wall, including the dependence on risk factors for CVD, in arbitrarily healthy people of various age.Material and methods    The relationship of polymorphisms с.521С&gt;Т of AGT gene, Ins&gt;Del of AСE gene, с.894G&gt;T of NOS3 gene, - 238G&gt;A of TNF gene, - 1562С&gt;T of MMP9 gene, and c.214Т&gt;С of CYBA gene with indexes of changes in the arterial wall and risk factors for CVD was studied in 160 arbitrarily healthy people by building models of multiple logistic regression and also by analyzing frequencies of co-emergence of two signs with the Pearson chi-squared test (χ2) and Fisher exact test.Results    The DD-genotype of Ins&gt;Del ACE gene polymorphism was correlated with increased PWV (p=0.006; odds ratio (OR) =3.41, 95 % confidence interval (CI): 1.48-8.67) and ED (p=0.014; OR=2.60, 95 % CI: 1.22-5.68). The GG genotype of с.894G&gt;T NOS3 gene polymorphism was correlated with ED (p=0.0087; OR=2.65, 95 % CI: 1.26-5.72); the ТТ-genotype of с.894G&gt;T NOS3 gene polymorphism was correlated with ASP (p=0.033; OR=0.034, 95 % CI: 0.001-0.549).Conclusion    Polymorphic variants of AСE and NOS3 genes correlated with ED, increased arterial wall stiffness, and the presence of subclinical changes in the arterial wall.

The association between CYBA gene C242T variant and risk of metabolic syndrome

BACKGROUND

Both inflammation and oxidative stress may contribute to pathogenesis of metabolic syndrome (MetS). The C242T polymorphism (rs4673) in the CYBA gene, as the main components of NAD (P) H oxidase, causes inter-individual variability in the enzyme activity. We aimed to investigate the association between this polymorphism with MetS and its components.

METHODS

Two hundred nine patients with MetS and 232 controls were included in this study. MetS was defined based on NCEP ATP-III A criteria with some modifications. The C242T polymorphism within CYBA gene was determined by using PCR-based restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

After applying a multiple logistic regression model with adjusting for potential confounders of MetS including, age, sex, body mass index, hypertension, used medications, and diabetes mellitus, C242T polymorphism was found to be associated with the presence of MetS in men but not in the total population or in women. T allele as compared to C allele was associated with decreased odds of MetS in men (adjusted OR = 0.42, 95% CI = 0.24-0.74; P = .003), but not in women (adjusted OR = 1.03, 95% CI = 0.07-1.61; P = .890), or in the total population (adjusted OR = 0.72, 95% CI = 0.51-1.02; P = .063).

CONCLUSION

This study shows that T allele of C242T polymorphism in CYBA gene is protective against MetS in Iranian men but not in women. Further cohort studies with larger sample size in subgroups of men and women are required to confirm such association in other racial or ethnic group.

NADPH Oxidase Gene Polymorphism is Associated with Mortality and Cardiovascular Events in 7-Year Follow-Up

The CYBA gene encodes the regulatory subunit of NADPH oxidase, which maintains the redox state within cells and in the blood vessels. That led us to investigate the course of coronary artery disease (CAD) with regards to CYBA polymorphisms. Thus, we recruited 1197 subjects with coronary atherosclerosis and observed them during 7-year follow-up. Three CYBA polymorphisms: c.214C>T (rs4673), c.-932G>A (rs9932581), and c.*24G>A (1049255) were studied for an association with death, major adverse cardiovascular events (MACE) and an elective percutaneous coronary intervention or coronary artery bypass grafting (PCI/CABG). We found an association between the CYBA c.214C>T polymorphism and two end points: death and PCI/CABG. CYBA c.214TT genotype was associated with a lower risk of death than C allele (9.5% vs. 21%, p < 0.05) and a higher risk of PCI/CABG than C allele (69.3% vs. 51.7%, p < 0.01). This suggests that the CYBA c.214TT genotype may be a protective factor against death OR = 0.47 (95%CI 0.28–0.82; p < 0.01), while also being a risk factor for an elective PCI/CABG OR = 2.36 (95%CI 1.15–4.82; p < 0.05). Thus, we hypothesize that among patients with coronary atherosclerosis, the CYBA c.214TT genotype contributes to atherosclerotic plaque stability by altering the course of CAD towards chronic coronary syndrome, thereby lowering the incidence of fatal CAD-related events.

Beneficial Effect of Jojoba Seed Extracts on Hyperglycemia-Induced Oxidative Stress in RINm5f Beta Cells

Hyperglycemia occurs during diabetes and insulin resistance. It causes oxidative stress by increasing reactive oxygen species (ROS) levels, leading to cellular damage. Polyphenols play a central role in defense against oxidative stress. In our study, we investigated the antioxidant properties of simmondsin, a pure molecule present in jojoba seeds, and of the aqueous extract of jojoba seeds on fructose-induced oxidative stress in RINm5f beta cells. The exposure of RINm5f beta cells to fructose triggered the loss of cell viability (-48%, p < 0.001) and disruption of insulin secretion (p < 0.001) associated with of reactive oxygen species (ROS) production and a modulation of pro-oxidant and antioxidant signaling pathway. Cell pre-treatments with extracts considerably increased cell viability (+86% p < 0.001) for simmondsin and +74% (p < 0.001) for aqueous extract and insulin secretion. The extracts also markedly decreased ROS (-69% (p < 0.001) for simmondsin and -59% (p < 0.001) for aqueous extract) and caspase-3 activation and improved antioxidant defense, inhibiting p22phox and increasing nuclear factor (erythroid-derived 2)-like 2 (Nrf2) levels (+70%, p < 0.001) for aqueous extract. Simmondsin had no impact on Nrf2 levels. The richness and diversity of molecules present in jojoba seed extract makes jojoba a powerful agent to prevent the destruction of RINm5f beta cells induced by hyperglycemia.

Three novel mutations in CYBA among 22 Iranians with Chronic granulomatous disease

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency caused by defect in one of the components of nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase enzyme. The enzyme is at least composed of membrane-bound subunits gp91-phox and p22-phox (also named cytochrome b₅₅₈ ), and cytosolic ones p40-phox, p47-phox and p67-phox. A defect in the enzyme activity leads to impaired intracellular killing of phagocytic cells. The CYBA gene encoding p22-phox is located on chromosome 16q24. In this study, new genetic changes of CYBA gene in 22 Iranian patients with autosomal recessive-CGD (AR-CGD) were identified. Twenty-two patients with CGD were referred to Immunology, Asthma and Allergy Research Institute (IAARI) and enrolled in this study based on defect in NADPH oxidase activity, demographic data and clinical histories. All patients had p22-phox deficiency based on Western blotting. Genomic DNA was extracted from peripheral blood mononuclear cells (PBMCs), and PCR followed by direct sequencing was performed to find p22-phox mutations. Mutation analysis of CYBA revealed 12 different mutations, including three novel mutations: one was deletion of exon 1, and two were point mutations in exon 3 (c.136G>A (p.Gly46Ser)), and exon 6 (c.388C>T (p.Gln130X)). Three new mutations of CYBA gene in four of 22 Iranian patients with AR-CGD were found. These three novel mutations can partly complete the database of Human Gene Mutation Database (HGMD) and other related ones. It can also be helpful for further prenatal diagnosis in the affected families. Given that currently bone marrow transplantation is considered to be the curative treatment for patients with CGD, finding mutations will also be useful for timely decision-making in bone marrow transplantation.

Oxidative Stress in Atherosclerosis

PURPOSE OF REVIEW

Atherosclerosis is now considered a chronic inflammatory disease. Oxidative stress induced by generation of excess reactive oxygen species has emerged as a critical, final common mechanism in atherosclerosis. Reactive oxygen species (ROS) are a group of small reactive molecules that play critical roles in the regulation of various cell functions and biological processes. Although essential for vascular homeostasis, uncontrolled production of ROS is implicated in vascular injury. Endogenous anti-oxidants function as checkpoints to avoid these untoward consequences of ROS, and an imbalance in the oxidant/anti-oxidant mechanisms leads to a state of oxidative stress. In this review, we discuss the role of ROS and anti-oxidant mechanisms in the development and progression of atherosclerosis, the role of oxidized low-density lipoprotein cholesterol, and highlight potential anti-oxidant therapeutic strategies relevant to atherosclerosis.

RECENT FINDINGS

There is growing evidence on how traditional risk factors translate into oxidative stress and contribute to atherosclerosis. Clinical trials evaluating anti-oxidant supplements had failed to improve atherosclerosis. Current studies focus on newer ROS scavengers that specifically target mitochondrial ROS, newer nanotechnology-based drug delivery systems, gene therapies, and anti-miRNAs. Synthetic LOX-1 modulators that inhibit the effects of Ox-LDL are currently in development. Research over the past few decades has led to identification of multiple ROS generating systems that could potentially be modulated in atherosclerosis. Therapeutic approaches currently being used for atheroslcerotic vascular disease such as aspirin, statins, and renin-angiotensin system inhibitors exert a pleiotropic antioxidative effects. There is ongoing research to identify novel therapeutic modalities to selectively target oxidative stress in atherosclerosis.

Association analysis of rs1049255 and rs4673 transitions in p22phox gene with coronary artery disease: A case-control study and a computational analysis

BACKGROUND

The p22phox gene encodes the main subunit of NADH/NADPH-oxidase. This enzyme is expressed in smooth muscle cells of arteries, and it produces the reactive oxygen species. On the other hand, oxidative stress plays a main role in the pathogenesis of coronary artery disease (CAD).

AIM

The aim of this study is to evaluate the association between rs4673 and rs1049255 polymorphisms of p22phox gene with CAD in an Iranian population which was followed with a computational analysis approach.

METHODS

In a cross-sectional study, we collected blood samples of 302 Iranian Caucasian including 143 patients and 159 healthy controls. Genotype of the polymorphisms was detected through PCR-RFLP method. A computational analysis was also performed using SNAP, Polyphen-2, Chou-Fasman, RNAsnp, and miRNA SNP databases.

RESULTS

Data of case control study demonstrated that CT genotype (R = 1.84, 95% CI = 1.13-3.00, p = 0.014) and T allele (OR = 1.53, 95% CI = 1.09-2.15, p = 0.013) of rs4673 polymorphism, have a significant association with enhanced risk of CAD. But rs1049255 analysis demonstrated the absence of such an association with CAD. Indeed, in silico data analysis demonstrated that rs4673 transition could impact on function of p22phox protein (SNAP score 56, expected accuracy 75%; Polyphen-2 score 0.99, sensitivity 0.09, specificity 0.99). Data derived from miRNA SNP database demonstrated that rs1049255 polymorphism increases the affinity of attachment between has-miR-3689a-3b with 3'-UTR of p22phox gene.

CONCLUSION

Our data demonstrated that rs4673 transition may be involved in susceptibility to CAD and could be applied as a potential biomarker for this disease.

Roles of Vascular Oxidative Stress and Nitric Oxide in the Pathogenesis of Atherosclerosis

Major reactive oxygen species (ROS)–producing systems in vascular wall include NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase, xanthine oxidase, the mitochondrial electron transport chain, and uncoupled endothelial nitric oxide (NO) synthase. ROS at moderate concentrations have important signaling roles under physiological conditions. Excessive or sustained ROS production, however, when exceeding the available antioxidant defense systems, leads to oxidative stress. Animal studies have provided compelling evidence demonstrating the roles of vascular oxidative stress and NO in atherosclerosis. All established cardiovascular risk factors such as hypercholesterolemia, hypertension, diabetes mellitus, and smoking enhance ROS generation and decrease endothelial NO production. Key molecular events in atherogenesis such as oxidative modification of lipoproteins and phospholipids, endothelial cell activation, and macrophage infiltration/activation are facilitated by vascular oxidative stress and inhibited by endothelial NO. Atherosclerosis develops preferentially in vascular regions with disturbed blood flow (arches, branches, and bifurcations). The fact that these sites are associated with enhanced oxidative stress and reduced endothelial NO production is a further indication for the roles of ROS and NO in atherosclerosis. Therefore, prevention of vascular oxidative stress and improvement of endothelial NO production represent reasonable therapeutic strategies in addition to the treatment of established risk factors (hypercholesterolemia, hypertension, and diabetes mellitus).

The CYBA Gene (⁎)49A>G Polymorphism (rs7195830) Is Associated with Hypertension in Patients with Coronary Artery Disease

Purpose. Single nucleotide polymorphisms of the CYBA gene may modify the risk of coronary artery disease (CAD). The aim of the present study was to investigate whether the ^⁎49A>G (rs7195830) polymorphism is associated with CAD. Materials and Methods. CYBA gene ^⁎49A>G polymorphism was determined in 481 subjects: 242 patients with premature CAD and 239 age and sex matched controls using the fluorescently labeled allele-specific oligonucleotides method. Results. The frequency of the ^⁎49G allele carrier state was significantly higher in patients than in controls (84.8% versus 76.6%, resp., P = 0.020), as well as the frequency of the ^⁎49G allele (62.2% versus 54.0%, P = 0.009). Both factors were associated with CAD in the analyzed population (OR = 1.70, 95% CI: 1.04–2.76 for GG+AG versus AA and OR = 1.40, 95% CI: 1.08–1.83 for ^⁎49G versus  ^⁎49A). Carrier state of the ^⁎49G allele was a stronger and independent risk factor for CAD among women (OR = 4.35, 95% CI: 1.50–13.20, P = 0.002), as well as the ^⁎49G allele (OR = 2.25, 95% CI: 1.34–3.77, P = 0.001). The ^⁎49G allele carrier state was also associated with left ventricular hypertrophy in patients with coronary artery disease (P = 0.015). Conclusion. The CYBA gene ^⁎49A>G polymorphism modifies the risk of coronary artery disease.

p22phox C242T Single-Nucleotide Polymorphism Inhibits Inflammatory Oxidative Damage to Endothelial Cells and Vessels

BACKGROUND

The NADPH oxidase, by generating reactive oxygen species, is involved in the pathophysiology of many cardiovascular diseases and represents a therapeutic target for the development of novel drugs. A single-nucleotide polymorphism, C242T of the p22(phox) subunit of NADPH oxidase, has been reported to be negatively associated with coronary heart disease and may predict disease prevalence. However, the underlying mechanisms remain unknown.

METHODS AND RESULTS

With the use of computer molecular modeling, we discovered that C242T single-nucleotide polymorphism causes significant structural changes in the extracellular loop of p22(phox) and reduces its interaction stability with Nox2 subunit. Gene transfection of human pulmonary microvascular endothelial cells showed that C242T p22(phox) significantly reduced Nox2 expression but had no significant effect on basal endothelial O2 (.-) production or the expression of Nox1 and Nox4. When cells were stimulated with tumor necrosis factor-α (or high glucose), C242T p22(phox) significantly inhibited tumor necrosis factor-α-induced Nox2 maturation, O2 (.-) production, mitogen-activated protein kinases and nuclear factor κB activation, and inflammation (all P<0.05). These C242T effects were further confirmed using p22(phox) short-hairpin RNA-engineered HeLa cells and Nox2(-/-) coronary microvascular endothelial cells. Clinical significance was investigated by using saphenous vein segments from non-coronary heart disease subjects after phlebotomies. TT (C242T) allele was common (prevalence of ≈22%) and, in comparison with CC, veins bearing TT allele had significantly lower levels of Nox2 expression and O2 (.-) generation in response to high-glucose challenge.

CONCLUSIONS

C242T single-nucleotide polymorphism causes p22(phox) structural changes that inhibit endothelial Nox2 activation and oxidative response to tumor necrosis factor-α or high-glucose stimulation. C242T single-nucleotide polymorphism may represent a natural protective mechanism against inflammatory cardiovascular diseases.

Association of CYBA G640A variation with coronary artery disease in Indians

INTRODUCTION

Oxidative stress induces atherosclerosis by triggering an inflammatory cascade within the vascular wall.

OBJECTIVE

To investigate the role of pro-oxidant and antioxidant gene variations with CAD in Indian subjects.

MATERIALS & METHODS

It's a case-control study and genotyping for the variants MPO G-463A, CYBA G640A, SOD2 Val16Ala and CAT C-262T were performed by conventional PCR techniques.

RESULTS

Only CYBA G640A variant allele was found to be significantly (p = 0.0075) associated with CAD.

CONCLUSION

Although CYBA G640A variation was found to be significant, a larger study is needed to validate these results and establish its role as a biomarker.

Meta-analysis of C242T polymorphism in CYBA genes: risk of acute coronary syndrome is lower in Asians but not in Caucasians

BACKGROUND

A lot of studies have demonstrated that C242T polymorphism in CYBA genes may play an important role in the pathological process of acute coronary syndrome (ACS). However, the results are not consistent. To further evaluate this debate, we performed a meta-analysis to determine the relationship between C242T polymorphism and ACS.

METHODS AND RESULTS

We screened PubMed/MEDLINE, EBSCIO, and EMBASE research reports until Mar. 2014 and extracted data from 10 studies involving 6102 ACS patients and 8669 controls. Subgroup analysis by ethnicity documented a significant decreased risk of ACS for C242T polymorphism in the Asian population under allelic comparison (odd ratio (OR) 0.73; 95% confidence intervals (CI) 0.64-0.83), dominant model (OR 0.71; 95% CI 0.62-0.82), and homozygote comparison (OR 0.57; 95% CI 0.35-0.92). However, in the overall population and especially with Caucasians, no significant association was uncovered. Further meta-regression analysis revealed that the heterogeneity among studies was largely attributed to ethnicity. No publication bias was detected through a funnel plot and an Egger's linear regression test.

CONCLUSIONS

Taken together, our results suggest that the C242T polymorphism might be a protective factor against developing ACS in the Asian population. Further researches will be needed to identify the confounding factors which modified the protective effect of T allele among Caucasians.

CYBA encoding p22(phox), the cytochrome b558 alpha polypeptide: gene structure, expression, role and physiopathology

P22(phox) is a ubiquitous protein encoded by the CYBA gene located on the long arm of chromosome 16 at position 24, containing six exons and spanning 8.5 kb. P22(phox) is a critical component of the superoxide-generating nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs). It is associated with NOX2 to form cytochrome b558 expressed mainly in phagocytes and responsible for the killing of microorganisms when bacterial and fungal infections occur. CYBA mutations lead to one of the autosomal recessive forms of chronic granulomatous disease (AR22(0)CGD) clinically characterized by recurrent and severe infections in early childhood. However, p22(phox) is also the partner of NOX1, NOX3 and NOX4, but not NOX5, which are analogs of NOX2, the first identified member of the NOX family. P22(phox)-NOX complexes have emerged as one of the most relevant sources of reactive oxygen species (ROS) in tissues and cells, and are associated with several diseases such as cardiovascular and cerebrovascular diseases. The p22(phox)-deficient mouse strain nmf333 has made it possible to highlight the role of p22(phox) in the control of inner ear balance in association with NOX3. However, the relevance of p22(phox) for NOX3 function remains uncertain because AR22(0)CGD patients do not suffer from vestibular dysfunction. Finally, a large number of genetic variations of CYBA have been reported, among them the C242T polymorphism, which has been extensively studied in association with coronary artery and heart diseases, but conflicting results continue to be reported.

Genetics of coronary artery disease and myocardial infarction

Atherosclerotic coronary artery disease (CAD) comprises a broad spectrum of clinical entities that include asymptomatic subclinical atherosclerosis and its clinical complications, such as angina pectoris, myocardial infarction (MI) and sudden cardiac death. CAD continues to be the leading cause of death in industrialized society. The long-recognized familial clustering of CAD suggests that genetics plays a central role in its development, with the heritability of CAD and MI estimated at approximately 50% to 60%. Understanding the genetic architecture of CAD and MI has proven to be difficult and costly due to the heterogeneity of clinical CAD and the underlying multi-decade complex pathophysiological processes that involve both genetic and environmental interactions. This review describes the clinical heterogeneity of CAD and MI to clarify the disease spectrum in genetic studies, provides a brief overview of the historical understanding and estimation of the heritability of CAD and MI, recounts major gene discoveries of potential causal mutations in familial CAD and MI, summarizes CAD and MI-associated genetic variants identified using candidate gene approaches and genome-wide association studies (GWAS), and summarizes the current status of the construction and validations of genetic risk scores for lifetime risk prediction and guidance for preventive strategies. Potential protective genetic factors against the development of CAD and MI are also discussed. Finally, GWAS have identified multiple genetic factors associated with an increased risk of in-stent restenosis following stent placement for obstructive CAD. This review will also address genetic factors associated with in-stent restenosis, which may ultimately guide clinical decision-making regarding revascularization strategies for patients with CAD and MI.

Polymorphisms in NADPH oxidase CYBA gene modify the risk of ESRD in patients with chronic glomerulonephritis

End-stage renal disease (ESRD) was defined as start of renal replacement therapy or death due to kidney disease. However, death due to acute kidney injury was not included. It typically occurs when chronic renal failure progresses to a point where the kidneys are permanently functioning at less than 10% of their capacity. Oxidative stress (OS) plays a crucial role in ESRD. Nicotinamide adenine dinucleotide phosphate (NADPH) is one of the most important enzymes during oxidative stress. Cytochrome b light chain (CYBA), encoded by a polymorphic gene, which is a critical component of the nicotinamide adenine dinucleotide (NADH)/NADPH oxidase system and plays an important role in electron transport and superoxide anion production, is located on chromosome band 16q24 and has six exons spanning almost 7.76 kb of genomic DNA. CYBA gene polymorphisms can influence the activity of NADPH oxidase. To evaluate the association between CYBA gene polymorphisms and ESRD, we genotyped five CYBA polymorphisms using TaqMan allelic discrimination assay on DNA samples from 306 healthy controls and 332 patients with ESRD. Our results suggested that rs1049255 polymorphism of CYBA modified the risk of ESRD (p  =  0.019; OR  =  0.625; 95%CI  =  0.424-0.921). GG genotype and G allele might be a protective factor against the risk of ESRD, especially in patients with chronic glomerulonephritis.

Determinants of ventricular arrhythmias in human explanted hearts with dilated cardiomyopathy

BACKGROUND

The molecular and cellular determinants of ventricular tachycardia (VT) in patients with nonischaemic dilated cardiomyopathy (NIDCM) remain poorly defined.

MATERIALS AND METHODS

We examined 20 NIDCM hearts where VT was reported in 10 cases and VT was absent in 10 cases, using a double-blinded case-control study design, and assessed the molecular and cellular features of the adverse myocardial remodelling.

RESULTS

Explanted hearts from patients with VT showed greater hypertrophic changes based on cardiomyocyte cross-sectional area and expression of disease markers, and increased myocardial fibrosis which extended into the left ventricular and right ventricular outflow tract regions. The VT group also showed increased oxidative stress with reduction in reduced glutathione levels. Connexin 43 levels in the intercalated discs showed increased levels in the VT group with reduced phosphorylation. Microarray mRNA analysis of gene expression in the left ventricle (LV) free wall revealed several families of genes which were differentially upregulated or downregulated in hearts with documented VT compared to hearts without VT. Notably, we identified reduced expression of the Ca(2+) -activated K(+) channel (KCNN2) and increased expression of the transient receptor potential cation channel 7 (TRPM7) and intracellular chloride channel 3. Western blot analysis on LV membrane fractions showed reduced KCNN2 and increased TRPM7 levels in hearts with VT.

CONCLUSIONS

In explanted human hearts with NIDCM, VT is associated with greater hypertrophy, oxidative stress and myocardial fibrosis, differential gene expression, and altered ion channel levels indicative of a distinctive adverse myocardial remodelling process associated with clinically significant VT.

Relationship between C242T polymorphism and arterial stiffness in an apparently healthy population

Superoxide production is modulated by the C242T polymorphism of the CYBA gene. A major source of the superoxide anion that contributes to arterial stiffness is oxidase. We investigated the relationship between the C242T polymorphism and brachial-ankle pulse wave velocity (baPWV) in an apparently healthy population, while controlling for the amount of consumed cigarette. We measured baPWV non-invasively, recorded the detailed history of smoking and genotyped the C242T polymorphism in 856 participants. The CC genotype was related to a higher value of baPWV than the CT/TT genotype (1438.7±11.9 vs 1371.0±32.4 cm s(-1), β=-0.069, P=0.03) after adjustment for covariates. Further investigation showed an interaction between C242T polymorphism and smoking status with respect to baPWV (P<0.0001). For smokers, the CC genotype of C242T polymorphism was correlated with higher baPWV values compared with CT/TT genotype (1344.2±17.4 vs 1126.8±22.5 cm s(-1), β=-0.279, P<0.0001), whereas this relationship in the non-smokers was not significant (1485.5±15.1 vs 1499.0±41.5 cm s(-1), β=0.027, P=0.48). Additionally, for smokers who smoked at least 180 cigarette-years, the CC genotype participants showed higher values of baPWV compared with CT/TT polymorphism carriers (P⩽0.011). Our findings suggest that the C242T gene polymorphism is associated with arterial stiffness. Additionally, this relationship could be modified by smoking dose.

Genetic Variants of Cytochrome b-245, Alpha Polypeptide Gene and Premature Acute Myocardial Infarction Risk in an Iranian Population

Background

Oxidative stress induced by superoxide anion plays critical roles in the pathogenesis of coronary artery disease (CAD) and hence acute myocardial infarction (AMI). The major source of superoxide production in vascular smooth muscle and endothelial cells is the NADPH oxidase complex. An essential component of this complex is p22phox, that is encoded by the cytochrome b-245, alpha polypeptide (CYBA) gene. The aim of this study was to investigate the association of CYBA variants (rs1049255 and rs4673) and premature acute myocardial infarction risk in an Iranian population.

Methods

The study population consisted of 158 patients under the age of 50 years, with a diagnosis of premature AMI, and 168 age-matched controls with normal coronary angiograms. Genotyping of the polymorphisms was performed by the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP).

Results

There was no association between the genotypes and allele frequencies of rs4673 polymorphism and premature acute myocardial infarction (P>0.05). A significant statistical association was observed between the genotypes distribution of rs1049255 polymorphism and AMI risk (P=0.037). Furthermore, the distribution of AA+AG/GG genotypes was found to be statistically significant between the two groups (P=0.011).

Conclusions

Our findings indicated that rs1049255 but not rs4673 polymorphism is associated with premature AMI.

Tumor necrosis factor-alpha G-238A polymorphism and coronary artery disease risk: a meta-analysis of 4,222 patients and 4,832 controls

BACKGROUND

The aim of the present study was to investigate the association between tumor necrosis factor-alpha (TNF-α) gene G-238A polymorphism and risk of coronary artery disease (CAD) using a meta-analytical approach.

METHODS

The PubMed and Embase databases were searched for relevant publications up to January 13, 2015. Four authors (XPH, XDZ, XTZ, and ZJZ) independently selected the studies, extracted, and analyzed the data using the Comprehensive Meta-Analysis software. The sensitivity and subgroups analyses were also performed. Either a fixed effects or a random effects model was used to estimate pooled odds ratios (ORs) and their 95% confidence intervals (CIs).

RESULTS

Finally, ten articles including eleven case-control studies involving 4,222 patients and 4,832 controls were yielded. The results indicated no significant association between G-238A polymorphism and CAD risk (A vs G: OR =1.08, 95% CI =0.89-1.30; AA vs GG: OR =1.15, 95% CI =0.59-2.25; GA vs GG: OR =1.14, 95% CI =0.88-1.48; AA vs [GG + GA]: OR =1.09, 95% CI =0.56-2.14; (GA + AA) vs GG: OR =1.11, 95% CI =0.90-1.38). In the subgroup analyses, similar results were obtained with overall populations. The sensitivity analyses showed that the overall results were robust. No publication bias was detected.

CONCLUSION

Based on current evidence, we can conclude that TNF-α G-238A polymorphism might not be associated with CAD risk.

Association of the NAD(P)H oxidase p22 phox gene C242T polymorphism with type 2 diabetes mellitus, diabetic nephropathy, and carotid atherosclerosis with type 2 diabetes mellitus: A meta-analysis

Background

Several epidemiological studies have evaluated the association between the NAD(P)H oxidase p22 phox gene C242T polymorphism and the risk of type 2 diabetes mellitus (T2DM), diabetic nephropathy (DN), and carotid atherosclerosis with T2DM (CA), but the results are inconclusive. This meta-analysis was therefore designed to clarify these controversies.

Methods

Systematic searches were performed using electronic databases such as MEDLINE, PubMed, EMBASE, and China National Knowledge Infrastructure, as well as through manual searching of the references of identified articles. A total of 11 publications were eligible for this meta-analysis after running a search on the NAD(P)H oxidase p22 phox gene C242T polymorphism, including 7 with outcomes for T2DM, 7 with outcomes for DN, and 3 with outcomes for CA. The pooled odds ratio (OR) with a 95% confidence interval (CI) was calculated using a fixed effects model (FEM) or a random effects model (REM). Publication bias was tested by Begg's funnel plot analysis. Sensitivity analysis was also performed.

Results

The results showed a significant association between the NAD(P)H oxidase p22 phox gene C242T polymorphism and T2DM risk in the allelic model (REM: OR = 1.23, 95% CI = 1.06–1.43), additive model (FEM: OR = 1.61, 95% CI = 1.14–2.26), and recessive model (FEM: OR = 1.50, 95% CI = 1.10–2.05). A significant association was also observed for DN in the allelic model (REM: OR = 1.25, 95% CI = 1.06–1.47), additive model (FEM: OR = 1.61, 95% CI = 1.08–2.38), and dominant model (REM: OR = 1.26, 95% CI = 1.03–1.54). However, no association was observed for CA. Similar results were obtained in subgroup analysis based on ethnicity.

Conclusions

Results of this meta-analysis suggest that the NAD(P)H oxidase p22 phox gene 242T allele might be associated with an increased risk of T2DM and DN, but not CA.

•

There are significant association between P22 phox gene C242T polymorphism with T2DM DN risk but no significant association with CA.

Effect of apolipoprotein A1 genetic polymorphisms on lipid profiles and the risk of coronary artery disease

Background

The disorder of lipid metabolism and genetic predisposition are major risk factors for coronary artery disease (CAD). Variants in the apolipoprotein A1 (APOA1) gene play an important role in the regulation of lipids. The objective of the present study was to investigate the effect of two polymorphisms (-75 G/A and +83 C/T) of APOA1 on lipid profiles and the risk of CAD.

Methods

A total number of 300 subjects with CAD and 300 age and sex matched healthy controls were enrolled for the study. Genotyping of the APOA1 was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) combined with gel electrophoresis, and then confirmed by direct sequencing.

Results

The frequencies of APOA1 -75 AA genotype [odds ratio (OR) =0.50, 95 % confidence interval (CI) = 0.28, 0.88; P = 0.02] and APOA1 -75 A allele (OR =0.76, 95 % CI = 0.59, 0.98; P = 0.04) were significantly lower in CAD than in controls. The APOA1 -75 A allele was significantly associated with increasing serum concentrations of ApoA1 and high-density lipoprotein cholesterol (HDL-C) (P < 0.001).

Conclusions

The individuals with the APOA1 -75 A allele were likely to have a lower risk of CAD as a result of its effect on higher serum concentrations of ApoA1 and HDL-C.