NADH/NADPH oxidase p22 phox C242T polymorphism and coronary artery disease in the Australian population

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.

Clinical Application of NOX Activity and Other Oxidative Biomarkers in Cardiovascular Disease: A Critical Review

SIGNIFICANCE

The oxidative stress theory of atherosclerosis is based on the assumption that the production of reactive oxidant species (ROS) by blood, as well as resident cells of the artery wall, elicits the formation of oxidized low-density lipoproteins (ox-LDL), which, in turn, promotes a series of inflammatory responses, ultimately leading to atherosclerotic plaque. This theory prompted the development of new laboratory methodologies that aimed at assessing the relationship between oxidative stress and clinical progression of human atherosclerosis.

CRITICAL ISSUES

Markers assessing the oxidation of phospholipid and protein components of LDL were among the first to be developed. Clinical trials included cross-sectional as well as retrospective and prospective studies that, however, provided equivocal results. Thus, clear evidence that oxidative biomarkers add more to the risk stratification by common atherosclerotic risk factors is still lacking.

RECENT ADVANCES

More recently, the analysis of oxidative stress focused on enzymatic pathways generating ROS, such as NADPH oxidase and myeloperoxidase (MPO). Experimental and clinical studies suggest that both enzymes may be implicated in promoting atherosclerotic disease. Novel laboratory methodologies have been, therefore, developed to study NADPH oxidase and MPO in patients with stable atherosclerosis as well as in patients with acute coronary and cerebro-vascular syndromes.

FUTURE DIRECTIONS

This review will analyze the strengths and weaknesses of the current methodology to study these enzymes in human atherosclerosis with particular regard to their clinical application in several settings of cardiovascular disease. Clinical methodology and results of previous studies with regard to markers of LDL oxidation have also been reviewed as a useful background for the future development of clinical trials.

NADPH oxidase p22phox C242T polymorphism and ischemic cerebrovascular disease: an updated meta-analysis

Background

A growing number of studies on the associations between nicotinamide adenine dinucleotide phosphate (NADPH) oxidase p22^phox C242T polymorphism and risk of ischemic cerebrovascular disease have recently been published, but the results remain inconsistent.

Material/Methods

We performed an updated meta-analysis to evaluate this association. Eight case-control studies were included, involving 2045 cases and 2102 controls. Heterogeneity was assessed by the Q test and the I² statistic. Begg and Egger’s tests were conducted to evaluate publication bias. Odds ratio (OR) was tested to identify the associations.

Results

Significant associations between p22^phox gene C242T polymorphism and ischemic cerebrovascular disease (ICVD) risk were observed in the allelic genetic model (OR=1.33, 95% confidence interval [CI] 1.00–1.77, p=0.048). No statistical significant association was found in the dominant model (OR=0.74, 95% CI 0.54–1.02, p=0.064) and recessive model (OR=1.40, 95% CI 0.89–2.19, p=0.146). Subgroup analysis showed an association in European populations for recessive model (OR=2.13, 95% CI 1.06–4.26, p=0.034) and no significant evidence of association in Asian populations was found (dominant model: OR=0.64, 95% CI 0.41–1.00, p=0.05; recessive model: OR=0.98, 95% CI 0.53–1.81, p=0.948; allelic model: OR=1.51, 95% CI 0.98–2.32, p=0.061).

Conclusions

p22^phox gene C242T polymorphism was associated with ICVD risk in the allelic genetic model, as well as in European populations for recessive model. No evidence showed association between p22^phox gene C242T polymorphism and ICVD risk in the dominant model and recessive model. Furthermore, no association existed in Asian populations for any of the 3 genetic models and European populations in the dominant model and allelic model.

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

Background

Coronary artery disease (CAD) is a leading cause of mortality in many countries. Considerable studies have been carried out to investigate the relationship between the C242T and A640G polymorphisms of CYBA gene and CAD, but the results were still inconsistent. Hence we conducted a meta-analysis to clarify the association.

Methods and Results

A total of 21 eligible literatures were included in the meta-analysis. We observed a significant decreased risk of CAD for C242T polymorphism in Asian population under an allelic model (OR 0.75; 95% CI 0.67–0.84) and a dominant model (OR 0.69; 95% CI 0.61–0.79), however, in overall population and other population no significant association was revealed. We also found A640G polymorphism may contribute to reducing CAD risk under an allelic model (OR 0.84; 95% CI 0.75–0.93), dominant model (OR0.77; 95% CI 0.64–0.92) and recessive model (OR0.82; 95% CI 0.69–0.97). No publication bias was found.

Conclusion

Our meta-analysis confirmed a protective effect of C242Tpolymorphism on CAD in Asian population and indicated that A640G polymorphism was significantly associated with decreased risk of CAD.

An association between polymorphism of the NADH/NADPH oxidase p22phox (phagocyte oxidase) subunit and aging in Turkish population

BACKGROUND AND AIMS

Aging is a complex and multifactorial process that is stimulated by a number of factors including genes and life-style. It is thought that the production of reactive oxygen species (ROS) in the face of antioxidant enzymes and molecules is related to aging and age-related diseases. NAD(P)H oxidase system is the predominant cellular source of ROS, and p22phox, the major component of that system, is essential for the activation of NAD(P)H oxidase. The aim of this study was to investigate the association between p22phox C242T single nucleotide polymorphism and aging in Turkish population.

METHODS

Blood samples were collected from 332 volunteers between 18 and 95 years of age and were classified into three groups according to their ages as <65, 65-84 and ≥ 85. p22phox C242T polymorphism was genotyped by PCR-RFLP method.

RESULTS

CC genotype frequency in the C242T polymorphism is higher in older group (≥ 85) than younger groups (<65 and 65-85), whereas CT + TT genotype frequency is lower in older group. When the p22phox C242T polymorphism was compared with the mean ages and age groups, statistically significant associations were found.

CONCLUSIONS

We showed for the first time that human aging is significantly associated with p22phox C242T genotypes in Turkish population, being highest in CC, intermediate in CT, and lowest in TT homozygote. It is plausible to suggest that CC genotype might protect people from chronic inflammation, diseases as well as from oxidative stress and, thus, individuals with CC genotype might be more advantageous for aging as compared to those with CT + TT genotypes.

Relationship of the p22phox (CYBA) gene polymorphism C242T with risk of coronary artery disease: a meta-analysis

Background

Observational and experimental studies have thus far been unable to resolve whether the CYBA C242T polymorphism is associated with coronary artery disease (CAD). Therefore, we undertook a comprehensive meta-analysis to more precisely evaluate the influence of this polymorphism on CAD and potential biases.

Methods

We screened MEDLINE, Embase, CNKI, Wanfang and CBM up to January 2013 and extracted data from 22 studies with 9,279 CAD patients and 9,349 controls. A random-effects model was exploited to synthesize the inconsistent outcomes of the individual studies, while addressing between-study heterogeneity and publication bias.

Results

The CYBA C242T polymorphism conformed to Hard-Weinberg Equilibrium for all studies (P>0.05). Overall comparison of the T allele with the C allele produced a non-significant risk estimate for CAD but with striking heterogeneity (T versus C: P = 0.87, OR = 0.99, 95%CI 0.89–1.11, P_{heterogeneity}<0.0001, I² = 67.8%). However, subgroup analysis by ethnicity documented that the T allele carriers had a marginal risk increase (21%) of CAD among Caucasians (recessive genetic model: P = 0.05, 95%CI 1.00–1.46, P_{heterogeneity} = 0.15, I² = 29.1%). Then data were divided into study design, the significance of CAD risk increase was substantially strengthened in matched case-control studies (allele comparison: P = 0.02, OR = 1.13, 95%CI 1.02–1.26, P_{heterogeneity} = 0.24, I² = 21.6%).Further meta-regression analysis identified that a large proportion of heterogeneity was explained by body mass index (BMI) (P = 0.03, OR = 1.07, 95%CI 1.01–1.15) and study design (P = 0.03, OR = 1.30, 95%CI 1.02–1.64).There was no obvious publication bias as verified by funnel plot and Egger's linear regression test (t = −0.25, P = 0.81 for allele comparison).

Conclusion

Taken together, our results suggested the CYBA C242T polymorphism might be a risk-conferring factor on developing CAD and BMI and study design were probable sources of between-study heterogeneity.

Association of the C242T polymorphism in the NADPH oxidase p22 phox gene with carotid atherosclerosis in Slovenian patients with type 2 diabetes

Oxidative stress plays an important role in the pathogenesis of diabetes and its complications. Genetic variations of enzymes producing reactive oxygen species could change their activity, thus contributing to the susceptibility to oxidative stress. The aim of this study was to examine the role of the NADPH oxidase C242T polymorphism in the development of carotid atherosclerosis in patients with type 2 diabetes. 286 diabetic patients and 150 healthy controls were enrolled in the study. Carotid atherosclerosis was quantified ultrasonographically as carotid intima-media thickness, plaque score (0-6) and plaque type (1-5). Diabetic patients were divided into low and high risk groups based on ultrasound phenotypes of carotid atherosclerosis. Genotypes were determined by real-time PCR. Levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) were measured by enzyme-linked immunosorbent assay (ELISA). Diabetic patients demonstrated a statistically significant difference compared to healthy controls in the following parameters: age, BMI, waist circumference, smoking prevalence, glucose, triglyceride and 8-OHdG serum levels. Control subjects had significantly higher levels of HDL, LDL and total cholesterol than diabetics (p < 0.001). The NADPH C242T polymorphism was not related with clinical characteristics, lipid parameters and 8-OHdG serum levels. We found no significant difference in the NADPH genotype distribution between diabetics and controls (p = 0.19) nor between low and high risk subgroups of diabetics (mean CIMT: p = 0.67; plaque score: p = 0.49, plaque type: p = 0.56). In the present study the NADPH C242T polymorphism was not associated with the degree of oxidative stress and carotid atherosclerosis. Further studies will show if it can be used as a genetic marker for carotid atherosclerosis in diabetic patients.

NADPH oxidases in cardiovascular disease: insights from in vivo models and clinical studies

NADPH oxidase family enzymes (or NOXs) are the major sources of reactive oxygen species (ROS) that are implicated in the pathophysiology of many cardiovascular diseases. These enzymes appear to be especially important in the modulation of redox-sensitive signalling pathways that underlie key cellular functions such as growth, differentiation, migration and proliferation. Seven distinct members of the family have been identified of which four (namely NOX1, 2, 4 and 5) may have cardiovascular functions. In this article, we review our current understanding of the roles of NOX enzymes in several common cardiovascular disease states, with a focus on data from genetic studies and clinical data where available.

Association of p22phox gene C242T polymorphism with coronary artery disease: a meta-analysis

INTRODUCTION

The C242T polymorphism of p22phox gene (rs4673) has been linked to the reduced coronary artery disease (CAD) risk, but results in the published literatures are controversial. A meta-analysis was performed to assess the effect of this polymorphism on the CAD risk.

METHODS

A comprehensive search was conducted to identify all studies on the association of p22phox gene C242T polymorphism with CAD risk. The fixed or random effect pooled measure was selected based on the homogeneity test among studies. Heterogeneity among studies was evaluated using Q test and the I(2) of Higgins and Thompson. Meta-regression was used to explore the sources of between-study heterogeneity. Publication bias was estimated using modified Egger's linear regression test proposed by Harbord etal.

RESULTS

We identified 15 published articles including 6273 CAD cases and 5045 controls. In this studied overall and non-Asian populations, we didn't found any significant association of p22phox gene C242T polymorphism with CAD in any of codominant, dominant, and recessive models. Only in Asian population, both fixed effect model (FEM) and random effect model (REM) indicated the significant protective effect both in codominant (FEM: OR=0.771, 95%CI: 0.681-0.873; REM: OR=0.751, 95%CI: 0.607-0.930) and dominant (FEM: OR=0.714, 95%CI: 0.621-0.822; REM: OR=0.694, 95%CI: 0.538-0.895) models with strong evidence for between-study heterogeneity (I(2)=52.6% for codominant and I(2)=56.5% for dominant), but not in recessive model. No evidence of publication bias was detected.

CONCLUSIONS

The results suggested a significant heterogeneity across ethnicities about the relationship between the T allele of p22phox gene C242T polymorphism and reduced CAD risk, with a significant protective effect only in Asian population that needs to be confirmed by further studies.

CYP1A1, CYP1A2 and CYBA gene polymorphisms associated with oxidative stress in COPD

BACKGROUND

The genetic susceptibility to chronic obstructive pulmonary disease (COPD) depends on detoxification and antioxidant enzymes, which detoxify cigarette smoke reactive components that, otherwise, generate oxidative stress.

METHODS

In a case-control study of 346 subjects with and without COPD, we examined the polymorphisms 462Ile/Val, 3801T/C of CYP1A1, -3860G/A of CYP1A2 and -930A/G, 242C/T of CYBA individually or in combination and their contribution to oxidative stress markers by measuring malondialdehyde (MDA), catalase (CAT), glutathione (GSH) and glutathione peroxidase (GPx).

RESULTS

COPD patients had significantly increased MDA concentration (p<0.001) and decreased CAT activity, GSH concentration, GPx activity (p< or =0.01). The patients were over-represented by the alleles 462Val, 3801C of CYP1A1 and -930G, 242C of CYBA (p<0.001, p=0.003, p=0.030 and p=0.031, respectively) and consequently the haplotypes of same alleles i.e. 462Val:3801C, 462Val:3801T and -930G:242C (p=0.048, p=0.016 and p=0.039, respectively). Similarly, CYP1A1 and CYP1A2 haplotypes, 462Val:3860G and 462Val:3801T:3860G were significantly over-represented (p=0.001 and p=0.003), respectively in patients. The same alleles-associated genotype-combinations between genes were more prevalent in patients. Of note, the genotypes, 462Ile/Val+Val/Val, 3801TC+CC of CYP1A1 and -930AG+GG of CYBA associated with increased MDA concentration (p=0.018, p=0.045 and p=0.017, respectively), decreased CAT activity (p<0.0001, p=0.080 and p<0.0001, respectively) and GSH concentration (p<0.0001, p=0.0002 and p=0.011, respectively) in patients.

CONCLUSION

The identified alleles, its haplotypes and the genotype-combination along with increased oxidative stress, signify the importance in susceptibility to COPD.

C242T Polymorphism of NADPH Oxidase p22phox and Recurrence of Cardiovascular Events in Coronary Artery Disease

Objectives— The common C242T polymorphism in the gene for the p22phox subunit of NADPH oxidase has been reported to be negatively associated with oxidative stress, but whether it confers prognostic information is not yet clear.

Methods and Results— The incidence of major adverse cardiovascular events (MACE) were determined in 237 patients with coronary stenosis during a median follow-up of 7.8 years. The p22phox genotypes were evaluated in 213 patients (89.9%) by polymerase chain reaction and Rsa I. digestion. Plasma levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG), a marker of oxidative stress, were also measured. In the univariate analysis, patients with CT/TT genotypes showed reduced recurrence of cardiovascular deaths, nonfatal MI, and revascularization procedures compared with homozygous carriers of the C allele. After controlling for confounders, a significantly lower risk of new revascularization procedures (HR=0.31, 95% CI 0.12 to 0.70; P =0.014) remained associated with the T allele. The Kaplan–Meier analysis showed a longer survival free from fatal and nonfatal MI in carriers of T allele ( P <0.001). The presence of the 242T allele was associated with significantly reduced plasma concentrations of 8-OHdG.

Conclusions— The 242T allele was a predictor of lower risk of recurrence of cardiovascular events in high-risk patients and was associated with reduced systemic oxidative stress.

NADPH oxidase CYBA polymorphisms, oxidative stress and cardiovascular diseases

Oxidative stress plays a key role in the pathophysiology of several major cardiovascular diseases, including atherosclerosis, hypertension, heart failure, stroke and diabetes. ROS (reactive oxygen species) affect multiple tissues either directly or through NO depletion. ROS induce cardiovascular dysfunction by modulating cell contraction/dilation, migration, growth/apoptosis and extracellular matrix protein turnover, which contribute to vascular and cardiac remodelling. Of the several sources of ROS within the cardiovascular system, a family of multisubunit NADPH oxidases appears to be a predominant contributor of superoxide anion. Recent findings suggest a significant role of the genetic background in NADPH oxidase regulation. Common genetic polymorphisms within the promoter and exonic sequences of CYBA, the gene that encodes the p22(phox) subunit of NADPH oxidase, have been characterized in the context of cardiovascular diseases. This review aims to present the current state of research into these polymorphisms in their relationship to cardiovascular diseases.

Genetics and reverse epidemiology among patients on chronic hemodialysis

A reversal in the association between traditional and nontraditional risk factors and clinical outcomes is often encountered in patients with chronic illness, including among those with advanced chronic kidney disease (CKD) on maintenance hemodialysis (MHD). The effects of the malnutrition-inflammation complex syndrome (MICS) may play a significant role in the reversal of this risk factor-outcomes association. the MICS, this syndrome complex is not universal in its prevalence among MHD patients. The significant inter- and intra-individual differences in the prevalence of inflammation, oxidative stress, and malnutrition, indicates the influence of genetic factors in this variability. In recent years, enormous advancement in the field of molecular genetics, genomics and bioinformatics, have revolutionized studies of the genetic epidemiology of several diseases. However, genetic association studies are at a preliminary stage in the population with advanced CKD (Table 1). Preliminary studies of the impact of polyphisms in inflammation and oxidative stress-related genes and genes affecting body composition and metabolism suggest that genetic variation may indeed affect the phenotype of the MHD population. Further, some of these gene polymorphisms may also contribute to a reversal of the association between traditional risk factors, such as BMI, blood pressure, and cholesterol and clinical outcomes in this vulnerable patient population. Genetic studies in patients with advanced CKD pose enormous challenges, including recruitment of sufficient numbers of patients to achieve adequate statistical power, resolution of immense genotypic and phenotypic heterogeneity, and gene-environment and gene-gene interactions. However, well-designed adequately powered studies with carefully defined phenotypes may potentially allow definition of risk profiles characterized by combinations of relevant Single nucleotide polymorphisms in the setting of given environmental factors. Accurate risk stratification that takes into account genetic information would allow more informed targeting of pharmacologic intervention and better refined clinical trial methodologies.

NAD(P)H oxidase p22phoxC242T polymorphism and ischemic stroke in Japan: the Fukuoka Stroke Registry and the Hisayama study

The C242T polymorphism of p22phox, a component of NAD(P)H oxidase, may have an impact on cardiovascular diseases; however, the association between this polymorphism and brain infarction is not fully understood. Here, we investigate the relationship between the C242T polymorphism and brain infarction in Japan. We recruited 1055 patients with brain infarction and 1055 control subjects. A chi-squared test revealed that the T-allele frequency was lower in patients with cardioembolic infarction (5.6%) than in control subjects (11.0%, P < 0.001); however, allele frequencies in patients with lacunar and atherothrombotic infarction (11.2%) were not significantly different from those in control subjects (11.0%). A multivariate-adjusted conditional logistic regression analysis also revealed no association between CT + TT genotype, and lacunar and atherothrombotic infarction (odds ratio = 0.97, 95% confidence interval: 0.72-1.32). To investigate the functional effects of the C242T polymorphism, we examined superoxide production in COS-7 cells cotransfected with Nox4 and p22phox of each genotype. The superoxide-producing activity in those cells expressing p22phox with the T allele was not significantly different from that in cells expressing p22phox with the C allele. The present results suggest that the p22phox C242T polymorphism may have a protective effect against cardioembolic infarction, but is not related to lacunar and atherothrombotic infarction in Japan.

Polymorphism C242T of the gene of the p22phox subunit for nicotinamide adenine dinucleotide phosphate oxidase, and erythrocytic antioxidant enzymes, in patients with tetralogy of Fallot

BACKGROUND

Nicotinamide adenine dinucleotide phosphate oxidase of the vascular cell membrane is an important source of reactive oxygen species. The aim of our study was to evaluate the possible influence of the p22phox C242T gene polymorphism on blood pressure and some markers of oxidative stress in children with tetralogy of Fallot.

METHODS

After surgical repair in early life, we recruited 38 children, aged 11.7 plus or minus 3.2 years, including 185 healthy individuals as controls for the purposes of establishing frequencies of alleles and genotypes. From this latter group, we matched a sub-sample of 53 healthy caucasian children, aged 11.0 plus or minus 1.0 years, in order to compare enzymic activities.

RESULTS

The children with tetralogy of Fallot showed significantly lower values of low-molecular-weight protein tyrosine phosphatase, particularly in carriers of CC genotype for the p22phox gene, with values of 145.2 plus or minus 77.4 micromol/g Hb/h, compared to controls, at 344.4 plus or minus 100.4 micromol/g Hb/h (p less than 0.001). Methemoglobin reductase activity in the patients with tetralogy was also lower in those with the CC genotype, at 9.8 plus or minus 3.2 micromol/g Hb-1 min(-1) compared to 24.2 plus or minus 11.8 micromol/g Hb(-1) min(-1) as measured in the controls (p less than 0.01). Lower systolic (p less than 0.05) and diastolic (p less than 0.01) blood pressures were also observed in the patients with tetralogy of Fallot.

CONCLUSIONS

Patients with tetralogy of Fallot having the CC genotype may be at a higher state of oxidative stress than T allele carriers, a finding which could have prognostic implications. Long term follow-up of these patients, however, may be necessary in order to draw definite conclusions.

Associations between the CYBA 242C/T and the MPO –463G/A Polymorphisms, Oxidative Stress and Cardiovascular Disease in Chronic Kidney Disease Patients

Genetic variations in the NADPH/MPO system in chronic kidney disease (CKD) patients might lead to altered activity of these enzymes, and thus to altered risk for oxidative stress (OS) and cardiovascular disease (CVD). We evaluated the impact of 242C/T CYBA and -463G/A MPO polymorphisms on OS and CVD mortality in stage 5 CKD patients starting dialysis. Two hundred and fifty-seven patients were genotyped using Pyrosequencing. Plasmalogen [dimethylacetal (DMA) 16/C16:0] was used as OS marker. CVD was assessed from patient history and clinical symptoms. Prevalence of CVD was higher (35%) in GG patients (MPO) compared to AG (26%) and AA (0%) patients (p < 0.01). Patients with CC genotype (CYBA) had lower levels of DMA 16/C16:0 (ratio 0.071 +/- 0.003) compared to TT patients (0.089 +/- 0.006; p < 0.05). These patients also had increased CVD mortality compared to CT and TT patients (chi(2) 2.19; p < 0.05). We conclude that genetic variations in the NADPH/MPO system are associated with OS, presence of CVD and CVD-related mortality in CKD patients.

The NOX family of ROS-generating NADPH oxidases: physiology and pathophysiology

For a long time, superoxide generation by an NADPH oxidase was considered as an oddity only found in professional phagocytes. Over the last years, six homologs of the cytochrome subunit of the phagocyte NADPH oxidase were found: NOX1, NOX3, NOX4, NOX5, DUOX1, and DUOX2. Together with the phagocyte NADPH oxidase itself (NOX2/gp91(phox)), the homologs are now referred to as the NOX family of NADPH oxidases. These enzymes share the capacity to transport electrons across the plasma membrane and to generate superoxide and other downstream reactive oxygen species (ROS). Activation mechanisms and tissue distribution of the different members of the family are markedly different. The physiological functions of NOX family enzymes include host defense, posttranlational processing of proteins, cellular signaling, regulation of gene expression, and cell differentiation. NOX enzymes also contribute to a wide range of pathological processes. NOX deficiency may lead to immunosuppresion, lack of otoconogenesis, or hypothyroidism. Increased NOX activity also contributes to a large number or pathologies, in particular cardiovascular diseases and neurodegeneration. This review summarizes the current state of knowledge of the functions of NOX enzymes in physiology and pathology.

NADPH oxidase (CYBA) and FcgammaR polymorphisms as risk factors for aggressive periodontitis: a case-control association study

INTRODUCTION

Neutrophils (PMN) in aggressive periodontitis (AgP) patients have been reported to be hyperactive especially with regards to superoxide production. Polymorphisms in genes influencing PMN function have been proposed as candidate risk factors for AgP. The aim of this study was to test the association of specific gene polymorphisms affecting PMN functions with AgP.

MATERIALS AND METHODS

Two hundred and twenty-four patients with confirmed diagnosis of AgP and 231 subjects with healthy periodontium took part in the study. A blood sample was collected from subjects and genotypes for p22phox (CYBA) NADPH oxidase, FP, Fcalpha and Fcgamma receptors were analysed in a blind fashion.

RESULTS

The C242T p22phox NADPH oxidase T allele was significantly associated with AgP in a multiple logistic regression model adjusting for confounders, and this was observed for all subjects [p = 0.002, odds ratio (OR) = 1.87, 95% confidence interval (CI) = 1.27-2.83] and Caucasians (p = 0.009, OR=2.07, 95% CI = 1.20-3.59). Concomitant presence of C242T p22phox NADPH oxidase T allele and FcgammaRIIIb NA1 homozygosity was associated with the generalized AgP phenotype in Caucasians (p = 0.001, OR = 30.35, 95% CI = 3.81-241.97).

CONCLUSIONS

C242T p22phox NADPH oxidase and FcgammaR polymorphisms may predispose to AgP through a modulation of neutrophil superoxide production.

The p22phox C242T gene polymorphism is associated with a reduced risk of angiographically verified coronary artery disease in a high-risk Finnish Caucasian population. The Finnish Cardiovascular Study

BACKGROUND

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is a major source of the superoxide anion, which may play an important role in the development of atherosclerosis and coronary artery disease (CAD). The p22phox, a component of the NADPH oxidase, is essential for the activation of this enzyme, and intensive expression of the p22phox has been reported in human atherosclerotic arteries. However, studies on the association of the C242T polymorphism in the p22phox gene with CAD have produced conflicting results, and the relation of this polymorphism with CAD is not well known in a population with acquired risk factors enhancing the NADPH-dependent superoxide production.

METHODS

As part of the Finnish Cardiovascular Study, a case-control study was conducted with 402 high-risk Finnish Caucasian patients undergoing coronary angiography. Genotyping was performed using the 5' nuclease TaqMan assay.

RESULTS

The prevalence of the T allele (TT + TC genotypes) was significantly lower among angiographically verified CAD patients (n = 250) than among control subjects (n = 152, P = .013). In contrast to subjects with the CC genotype, the T allele was found protective against CAD (odds ratio = 0.531, 95% CI 0.331-0.852, P = .009), and the results remained significant after adjustment for other significant coronary risk factors.

CONCLUSIONS

The T allele in the C242Tpolymorphism of the p22phox gene had a protective effect against the development of CAD despite the exposure of study subjects to risk factors related to excessive NADPH-dependent superoxide production.

The C242T CYBA polymorphism of NADPH oxidase is associated with essential hypertension

OBJECTIVE

Oxidative stress is implicated in hypertension. The reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidases are the main source of superoxide in phagocytic and vascular cells. The C242T polymorphism of CYBA, the human gene that encodes p22phox, has been found to be functionally associated with vascular NADPH oxidase activity in atherosclerotic patients. We investigated the association of the C242T polymorphism with hypertension and its potential impact on NADPH oxidase activity. We also analysed the interaction of C242T polymorphism with the -930A/G CYBA variant.

DESIGN

Case-control study in a random sample of 623 subjects (326 hypertensive patients and 297 normotensive controls) from the general population.

METHODS

CYBA polymorphisms were determined by restriction fragment length polymorphism (RFLP) or allelic discrimination. NADPH oxidase activity and p22phox expression were quantified in phagocytic cells by chemiluminescence and by northern and western blots, respectively.

RESULTS

The prevalence of the CC genotype and the C allele frequency were significantly higher (P < 0.05) in hypertensives than in normotensives. CC genotype remained associated with hypertension after adjusting for potential confounders in a logistic regression analysis. Increased phagocytic NADPH oxidase activity was observed in CC hypertensives compared with CT and TT hypertensives (P < 0.05). Enhanced plasma levels of von Willebrand factor were found in CC hypertensives compared with TT hypertensives (P < 0.05). The C242T polymorphism was not in linkage disequilibrium with the -930A/G CYBA promoter variation, which also associates with hypertension.

CONCLUSION

The C242T CYBA polymorphism is associated with essential hypertension. Furthermore, hypertensives carrying the CC genotype of this polymorphism exhibit features of NADPH oxidase-mediated oxidative stress and endothelial damage.

NAD(P)H oxidase p22phox gene C242T polymorphism, nitric oxide production, salt sensitivity and cardiovascular risk factors in Hispanics

Mutations in the NAD(P)H oxidase gene may be associated with abnormal superoxide generation, nitric oxide (NO) availability and cardiovascular diseases. We investigated the prevalence of the NAD(P)H oxidase p22phox gene C242T polymorphism, and its possible association with blood pressure, NO production, salt sensitivity and cardiovascular risk factors in Hispanics. Genotype frequencies were as follows: CC, 52.9%; CT, 40.3%; and TT, 6.8%. There were no significant differences in systolic blood pressure, diastolic blood pressure, age, weight, fasting and post-load glucose levels, LDL and HDL cholesterol, triglyceride and urinary albumin levels in subjects with CC, CT or the TT genotypes. Presence of the T allele was associated with increased salt sensitivity in women, but not in men. NO metabolite excretion was markedly decreased both in women and men with the TT genotype (CC: 868+/-79 micromol/day; CT: 839+/-75 micromol/day; TT: 534+/-78 micromol/day; P<0.05). In conclusion, the prevalence of the NAD(P)H oxidase p22phox gene C242T polymorphism in Venezuelans was comparable to that of Caucasians, but different from that of Chinese and Japanese. Although the T allele was not associated with cardiovascular risk factors, hyperinsulinaemia or hypertension, in women, it appeared to be a genetic susceptibility factor for salt sensitivity. Both in women and men, the p22phox gene may play a role in the genetic control of NO levels.

NAD(P)H oxidase and multidrug resistance protein genetic polymorphisms are associated with doxorubicin-induced cardiotoxicity

BACKGROUND

A significant number of patients treated with anthracyclines develop cardiotoxicity (anthracycline-induced cardiotoxicity [ACT]), mainly presenting as arrhythmias (acute ACT) or congestive heart failure (chronic ACT). There are no data on pharmacogenomic predictors of ACT.

METHODS AND RESULTS

We genotyped participants of the German non-Hodgkin lymphoma study (NHL-B) who were followed up for the development of heart failure for a median of >3 years. Single-nucleotide polymorphisms (SNPs) were selected from 82 genes with conceivable relevance to ACT. Of 1697 patients, 55 developed acute and 54 developed chronic ACT (cumulative incidence of either form, 3.2%). We detected 5 significant associations with polymorphisms of the NAD(P)H oxidase and doxorubicin efflux transporters. Chronic ACT was associated with a variant of the NAD(P)H oxidase subunit NCF4 (rs1883112, -212A-->G; symbols with right-pointing arrows, as edited?' odds ratio [OR], 2.5; 95% CI, 1.3 to 5.0). Acute ACT was associated with the His72Tyr polymorphism in the p22phox subunit (rs4673; OR, 2.0; 95% CI, 1.0 to 3.9) and with the variant 7508T-->A (rs13058338; OR, 2.6; 95% CI, 1.3 to 5.1) of the RAC2 subunit of the same enzyme. In agreement with these results, mice deficient in NAD(P)H oxidase activity, unlike wild-type mice, were resistant to chronic doxorubicin treatment. In addition, acute ACT was associated with the Gly671Val variant of the doxorubicin efflux transporter multidrug resistance protein 1 (MRP1) (OR, 3.6; 95% CI, 1.6 to 8.4) and with the Val1188Glu-Cys1515Tyr (rs8187694-rs8187710) haplotype of the functionally similar MRP2 (OR, 2.3; 95% CI, 1.0 to 5.4). Polymorphisms in adrenergic receptors previously demonstrated to be predictive of heart failure were not associated with ACT.

CONCLUSIONS

Genetic variants in doxorubicin transport and free radical metabolism may modulate the individual risk to develop ACT.

A beneficial effect of simvastatin on DNA damage in 242T allele of the NADPH oxidase p22phox in hypercholesterolemic patients

BACKGROUND

The effect of simvastatin on DNA damage in hypercholesterolemic patients was investigated, and the relationship between the C242T polymorphism of the NADPH oxidase p22phox gene and the antioxidant effects of simvastatin was examined.

METHODS

Simvastatin (20-40 mg /day) was administered for 8 weeks in 72 hypercholesterolemic patients. DNA damage in lymphocytes was quantified using single-cell gel electrophoresis (COMET assay) by measuring tail DNA (%), tail length (microm) and tail moment (tail length x % tail DNA/100).

RESULTS

Simvastatin significantly reduced DNA damage as expressed by tail DNA (%, p< 0.001), tail length (mum, p<0.001) and tail moment on the DNA in lymphocytes (p<0.001) after 8 weeks. The frequencies of the C242T genotypes for CC, TC, and TT were 75.0%, 23.6% and 1.4% in the subjects. In the presence of the 242T allele, there were higher levels of baseline DNA damage and also a greater improvement in the DNA damage after 8 week simvastatin treatment compared with the CC homozygotes.

CONCLUSION

Simvastatin significantly reduced DNA damage of hypercholesterolemic patients. This study showed that simvastatin has a beneficial effect on the improvement of DNA damage in patients with the 242T allele of NADPH oxidase p22phox gene.

Genetic polymorphisms of oxidative and antioxidant enzymes and arsenic-related hypertension

The association of 4 genetic polymorphisms, NAD(P)H oxidase, manganesesuperoxide dismutase (MnSOD), catalase, and endothelial nitric oxide synthase (e-NOS), was assessed with arsenic-related hypertension risk among 79 hypertensive cases and 213 controls in an arseniasis-hyperendemic area of Taiwan. Overall, MnSOD polymorphism significantly increased the risk of hypertension regardless of arsenic exposure. NADPH oxidase and eNOS polymorphisms were significantly associated with hypertension risk in the high arsenic exposure group; however, catalase polymorphism was not associated with hypertension. Groups were further stratified by triglyceride levels to evaluate whether the cumulative arsenic exposure combined the three polymorphisms together. The adjusted adds ratios (ORs) of at least two risk factors of the cumulative arsenic exposure and MnSOD, NADPH oxidase, and eNOS three-polymorphism combination versus any one risk factor of them were 0.8 (95% CI 0.3-2.3) for individuals with low triglyceride levels (<110 mg/dl) and 2.5 (95% CI 1.0-6.01) for high-triglyceride groups (>110 mg/dl), respectively. These results suggested that the NADPH oxidase, MnSOD, and e-NOS polymorphisms, but not catalase, might play a role in the development of arsenic-related hypertension, especially in subjects with high triglyceride levels.

Oxidative stress and cardiovascular risk: the role of vascular NAD(P)H oxidase and its genetic variants

Several risk factors for coronary artery disease (CAD) induce atherosclerosis through endothelial activation and dysfunction, and ample evidence now suggests that the balance between production and removal of reactive oxygen species (ROS) - a condition termed oxidative stress - is implicated in such processes. A main source of ROS in vascular cells is the reduced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase system. This is a membrane-associated enzyme, composed of five subunits, catalyzing the one-electron reduction of oxygen, using NADH or NADPH as the electron donor. One of the system subunits, termed p22-phox, has a polymorphic site on exon 4, associated with variable enzyme activity. This polymorphism is generated by a point mutation (C(242)T) producing a substitution of histidine with tyrosine at position 72, which affects one of the heme binding sites essential for the NAD(P)H enzyme activity. The consequent decrease of superoxide production thus characterizes a phenotype candidate for conferring to the carrier a reduced susceptibility to CAD. At present, however, the body of evidence from current literature is not yet sufficient to confirm or exclude the hypothesis that the C(242)T polymorphism protects from CAD. The functional effects of this polymorphism and the potential and its pathophysiological consequences also need further investigation.

Functional effects of NAD(P)H oxidase p22phox C242T mutation in human leukocytes and association with thrombotic cerebral infarction

BACKGROUND

Previous study showed that polymorphism of the NAD(P)H oxidase p22(phox) gene is associated with atherosclerosis, although others could not confirm such association. We investigated the association between p22(phox) C242T polymorphism and thrombotic cerebral infarction and the role of this polymorphism on superoxide-production activity in human neutrophils and promyelocytic HL-60 cells as a model system.

METHODS

PCR-RFLP analysis revealed that genotype and allele frequencies of C242T polymorphism in 120 patients with thrombotic cerebral infarction and 177 control subjects. The superoxide-production activity in neutrophils was determined by cytochrome c reduction assay. To clarify the role of p22(phox) C242T polymorphism on NAD(P)H oxidase activity, we used transgenic HL-60 cells transfected with expression plasmids carrying p22(phox) cDNAs with or without C242T polymorphism.

RESULTS

Genotype and allele frequencies of C242T polymorphism in patients and control subjects were not significantly different. The superoxide-production activity in neutrophils with T allele was higher than in neutrophils without T allele. Moreover, expression analysis showed that superoxide-production activity in p22(phox) C242T-expressing HL-60 cells were significantly higher than in p22(phox)-expressing HL-60 cells.

CONCLUSIONS

We conclude that C242T of p22(phox) gene is not involved in thrombotic cerebral infarction but more likely in increased NAD(P)H oxidase activity in phagocytes.

C242TCYBAPolymorphism of the NADPH Oxidase Is Associated With Reduced Respiratory Burst in Human Neutrophils

Oxidative stress contributes to the pathogenesis of atherosclerosis. p22phox-based NAD(P)H oxidases exist in the vessel wall, acting as important superoxide-generating systems in the vasculature. Some studies have identified reduced atherosclerosis in the presence of the C242T CYBA polymorphism, whereas others have not. Because vascular p22phox is identical to neutrophil p22phox, we studied the association between the C242T, A640G, and -930A/G CYBA polymorphisms and the quantity of superoxide produced from neutrophils isolated from healthy adults to determine if these polymorphisms had any functional impact on NADPH oxidase function. Neutrophils were isolated from 90 subjects by Percoll density gradient centrifugation. Genotypes were determined by polymerase chain reaction (PCR) and restriction mapping, as well as real-time PCR. The oxidative burst was stimulated with phorbol 12-myristate 13-acetate. Superoxide was quantified using the superoxide dismutase inhibitable oxidation of the spin probe hydroxylamine 1-hydroxy-3-carboxy-pyrrolidine, detected by electron paramagnetic resonance. Superoxide production was significantly affected by the C242T polymorphism, being 8.7+/-0.7, 7.9+/-0.6, and 5.9+/-1.2 micromol/L per minute per 10(6) neutrophils for the C242T CC, CT, and TT genotypes, respectively (P<0.05). In contrast, the A640G and the -930A/G polymorphisms did not alter the neutrophil respiratory burst. Phagocytic respiratory burst activity in homozygous individuals with the T allele of the C242T CYBA polymorphism is significantly lower than of wild-type carriers and heterozygous individuals. Because p22phox exists in both the neutrophil and vessel wall, vascular oxidative stress is likely diminished in individuals with this polymorphism.

Angiotensin-converting enzyme and p22phox polymorphisms and the risk of coronary heart disease in a low-risk Spanish population

OBJECTIVE

To evaluate the genetic contribution to myocardial infarction in a homogeneous Caucasian population (a Mediterranean Spanish population) with very low frequency of coronary heart disease (CHD).

DESIGN

We analyzed a total of 210 subjects, younger than 55 years, considered to be a low-risk population (104 cases of myocardial infarction and 106 control), and genotyped them (using polymerase chain reaction and sequencing) for the angiotensin-converting enzyme (ACE) insertion/deletion (ACE I/D) and for the C242T polymorphism of NADPH oxidase p22(phox). Also, we sequenced 23 alleles of the ACE gene (9 D and 14 I) for the region that includes the end of the intron 16 and the exon 17.

RESULTS

The ACE genotype-prevalence values for II, ID and DD were 4.81%, 28.85% and 66.34%, respectively, among the myocardial infarction patients, and 2.83%, 71.70% and 25.47% among controls. The statistical analysis comparing patients and controls revealed significant differences (chi(2)=25.09, P=0.00000055) between the two subpopulations. Also, we found a strong association between the genotype DD and the risk of suffering CHD (odds ratio (OR): 3.64; 95% CI: 2.37-8.07). The prevalence of the CC, TC and TT genotypes of p22(phox) gene among healthy controls proved to be 53.77%, 44.34% and 1.89%, while those of myocardial infarction were 58.65%, 39.42% and 1.93%, respectively. The association of C242T polymorphism of the p22(phox) gene with CHD was not statistically significant, (chi(2)=0.49, P=0.48). Logistic-regression analysis demonstrated that the independent risk factor for developing myocardial infarction was the DD genotype of ACE gene. Finally, our results indicate that alleles I and D of ACE gene are differentiated at three positions (nucleotide sites 14,480, 14,488 and 14,521) of which, the positions 14,480 and 14,488 were in absolute linkage disequilibrium.

CONCLUSIONS

Among subjects of a Mediterranean population with low risk for CHD, the presence of DD ACE genotype could be a risk factor for myocardial infarction, and we confirm the linkage disequilibrium between two nucleotide positions of the ACE gene and the polymorphism for an Alu insertion.

Relation between development of nephropathy and the p22phox C242T and receptor for advanced glycation end product G1704T gene polymorphisms in type 2 diabetic patients

OBJECTIVE

The development of diabetic nephropathy is considered to be associated with oxidative stress. NADPH oxidase and the receptor for advanced glycation end products (RAGE) have attracted attention as mechanisms of generating oxidative stress. We studied the relation between the genotypes of the NADPH p22phox C242T and RAGE G1704T polymorphisms and the development of diabetic nephropathy in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

Using a retrospective review of clinical data, we allocated 181 Japanese type 2 diabetic patients to one of two groups: patients without diabetic nephropathy (group N; n = 108) and patients developing diabetic nephropathy (group D; n = 73) for 10 years or more. The p22phox C242T and RAGE G1704T polymorphisms were examined by Taqman PCR methods.

RESULTS

The frequency of the p22phox CC genotype was significantly higher in group D than in group N (90 vs. 79%; P = 0.0427). The frequency of the RAGE GT + TT genotype was significantly higher in group D than in group N (26 vs. 13%; P = 0.0313). The frequency of the combination of p22phox CC and RAGE GT + TT genotypes was significantly higher in group D than in group N (22 vs. 8%; P = 0.0057). In multiple logistic regression analysis, systolic blood pressure, HbA(1c), triglycerides, and the combination of polymorphisms were shown to be independent variables.

CONCLUSIONS

These results suggest that assessment of the combination of NADPH p22phox C242T and RAGE G1704T polymorphisms may be useful in identifying the risk for developing diabetic nephropathy in type 2 diabetic patients.

Gender, ethnicity and genetics in cardiovascular disease: part 1: Basic principles

Prior to 1993, most drug efficacy and safety trials were conducted in white males, although gender and racial differences in pharmacodynamics and pharmacokinetics have been documented since the early 1900s. Over the last 2 decades, supported by the FDA and legislation, attempts to include more women and minorities in clinical drug trials have been made, with limited success. Yet, there are important differences in pathophysiology and pharmacogenetics, as well as pharmacotherapeutic effectiveness. This is the first of 2 articles that review the basic scientific principles of such differences. In particular, genetic polymorphisms of cardiovascular candidate genes and drug metabolism are described. The pharmacodynamic and pharmacokinetic variations among genders and ethnicities are summarized.

NAD (P) H oxidase p22 phox C242T polymorphism affects LDL particle size and insulin resistance in Japanese subjects

Elevated cardiovascular risk is associated with an increased number of small, dense low-density lipoprotein (LDL) particles, which exhibit increased susceptibility to lipid oxidation, however, the mechanism determining LDL particle size has never been fully elucidated. We have examined the association between the C242T polymorphism of the p22 phox gene, which is a small subunit of vascular NAD(P)H oxidase, and both LDL particle size and clinical characteristics in 260 healthy subjects. Peak LDL particle diameter (LDL-PPD) was measured by continuous disk polyacrylamide gel electrophoresis. Twenty-one of the 217 subjects with the CC genotype showed pattern B (median LDL-PPD under 25.5 nm), whereas, none of the 43 subjects with TC + TT genotypes showed pattern B. The pattern B fraction was significantly larger in the CC group than in the TC + TT group (p = 0.030). The subjects with the CC genotype also showed a significantly higher fasting glucose level, plasma insulin level, and insulin resistance index of homeostasis model assessment (HOMA-R) than those with the TC + TT genotype. Our data demonstrate that variation in the small NAD(P)H oxidase subunit p22 phox gene substantially influences LDL particle size and may also reflect differences in the insulin sensitivity of non-diabetic subjects.

Association of NAD(P)H oxidase p22 phox gene variation with advanced carotid atherosclerosis in Japanese type 2 diabetes

OBJECTIVE

To evaluate the association between the C242T polymorphism of the p22 phox gene, an essential component of NAD(P)H oxidase in the vasculature, with intima-media thickness (IMT) of the carotid artery and risk factors for atherosclerosis in type 2 diabetic subjects.

RESEARCH DESIGN AND METHODS

C242T polymorphism of the p22 phox gene was detected by polymerase chain reaction-restriction fragment-length polymorphism in 200 Japanese type 2 diabetic subjects and 215 nondiabetic subjects. We examined the association with this mutation and carotid atherosclerosis as well as the patients' clinical characteristics and the level of 8-hydroxy-2'deoxyguanosine (8-OHdG) as an index of oxidative DNA damage.

RESULTS

The diabetic subjects with the TC+TT genotypes displayed a significantly lower average IMT (1.13 +/- 0.31 vs. 1.31 +/- 0.34 mm; P = 0.0099) and a not significantly lower serum 8-OHdG level than those with the CC genotype, despite no difference in the risk factors. Stepwise multiple regression analysis showed that the risk factors for increased IMT in the diabetic subjects were systolic blood pressure (P = 0.0042) and p22 phox CC genotype (P = 0.0151). In nondiabetic subjects, the average IMT of the TC+TT group was not different from that of the CC group (0.85 +/- 0.14 vs. 0.94 +/- 0.30 mm, P = 0.417). Fasting plasma insulin concentration (41.4 +/- 15.6 vs. 64.2 +/- 59.4 pmol/l, P = 0.0098) and insulin resistance index of homeostasis model assessment (HOMA-R) (1.58 +/- 0.66 vs. 2.60 +/- 2.56, P = 0.0066) were significantly lower in the TC+TT group than in the CC group.

CONCLUSIONS

These results show that the C242T mutation in the p22 phox gene is associated with progression of asymptomatic atherosclerosis in the subjects with type 2 diabetes and is also associated with insulin resistance in nondiabetic subjects.

NADPH oxidase(s): new source(s) of reactive oxygen species in the vascular system?

Reactive oxygen species play an important role in a variety of (patho)physiological vascular processes. Recent publications have produced evidence of a role for putative non-phagocyte NADP oxidase(s) in the vascular production of reactive oxygen species. In the present review, we discuss the detection of the different components of NADP oxidase(s) in the vascular system, together with the putative role of reactive oxygen species produced by vascular NADPH oxidase(s), in both in vitro and in vivo studies.

The A640G and C242T p22(phox) polymorphisms in patients with coronary artery disease

Oxidative stress plays a significant role in the pathogenesis of coronary artery disease (CAD). A p22(phox)-based NAD(P)H oxidase acts as a potent superoxide-generating system in the vasculature. We studied the association of the A640G and the C242T polymorphisms with clinical risk factors, endothelial function, and severity of CAD in a cohort of 216 patients referred for coronary angiography. The frequency of p22(phox) genotypes for AA, AG, and GG was 22.5, 52.3, and 25.2%, and for CC, CT, and TT 35.5, 51.3, and 13.2%, respectively. The A640G and the C242T polymorphisms were not associated with severity of CAD and endothelial function. The frequency distribution of the genotypes among patients with or without angiographically significant CAD did not reach statistical significance. Our study does not support a functional role for the A640G or C242T polymorphisms either in the severity of CAD or in determining endothelial function in older men.

Increased NADPH oxidase activity, gp91phox expression, and endothelium-dependent vasorelaxation during neointima formation in rabbits

Reactive oxygen species including superoxide and hydrogen peroxide are important mediators in atherogenesis. We investigated the enzymatic source of vascular superoxide and its role in endothelium-dependent vasorelaxation during neointima formation. Silastic collars positioned around carotid arteries of rabbits for 14 days induced neointimal thickening. Using lucigenin-enhanced chemiluminescence, superoxide production was detectable in collared artery sections, but not in controls, only after inactivation of endogenous Cu2+/Zn2+-superoxide dismutase (Cu2+/Zn2+-SOD) with diethyldithiocarbamate (DETCA). Dihydroethidium staining indicated that endothelium and adventitia were the major sites of superoxide generation. Superoxide production in DETCA-treated collared arteries was enhanced further by NADPH and was inhibited by diphenyleneiodonium, suggesting NADPH oxidase was the source of the radical in collared arteries. Moreover, real-time PCR demonstrated 11-fold higher expression of the gp91phox subunit of NADPH oxidase in collared arteries than in controls. In vascular reactivity studies, endothelium-dependent vasorelaxation to acetylcholine did not differ between collared and control sections. However, treatment with DETCA reduced relaxations to acetylcholine in collared rings, but not in controls. NADPH further reduced relaxations to acetylcholine in DETCA-treated collared sections, but not in controls. In DETCA/NADPH-treated collared rings, sensitivity to nitroprusside, in contrast to acetylcholine, exceeded that of controls. Moreover, further treatment of such rings with exogenous Cu2+/Zn2+-SOD restored acetylcholine relaxations without altering nitroprusside responses. Thus, early neointimal lesions induced by periarterial collars are associated with elevated gp91phox expression and increased NAPDH-oxidase-dependent superoxide production in endothelium and adventitia. However, endothelium-dependent vasorelaxation is largely preserved due to the actions of Cu2+/Zn2+-SOD and increased smooth muscle sensitivity to nitric oxide.

NADH/NADPH oxidase p22 phox C242T polymorphism and lipid peroxidation in coronary artery disease

The nicotinamide adenine dinucleotide (NADH)/nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system is a major source of superoxide anion (.O2-) production in the human vasculature and may therefore influence lipid peroxidation and severity of atherosclerosis. This study aimed to investigate a hypothetical influence of the p22 phox C242T polymorphism on the generation of malondialdehyde (MDA), extent and clinical onset of coronary artery disease (CAD) in patients. We studied 108 male Caucasians with angiographically documented CAD and 45 controls free of vascular disease under 60 years of age. p22 phox C242T genotypes and MDA levels were determined. Additional information was obtained from each subject on classic risk factors and clinical events of CAD. Genotype distribution in CAD-patients and controls was thymine-thymine (TT): 13.8% (13.3%), cytosine-thymine (CT): 46.3% (53.3%) and cytosine-cytosine (CC): 39.8% (33.3%), respectively. No significant influence was seen of the p22 phox C242T polymorphism on corresponding mean MDA levels in both groups. Furthermore, age at onset of first time angina pectoris (AP) and myocardial infarction (MCI) was not significantly different between genotype groups. It is concluded that the C242T polymorphism of the p22 phox gene is not associated with lipid peroxidation as measured by MDA, and is not a genetic risk marker for CAD Caucasians.

Oxidative stress, human genetic variation, and disease

Oxidative stress has been implicated in numerous pathophysiological conditions and also aging. The tools for studying oxidative stress are now expanding as a result of the human genome effort and, in particular, expanding knowledge on human genetic variation. A few genetic variants, mostly in the form of single nucleotide polymorphisms of relevance to oxidative stress are already studied by a molecular epidemiologic approach. A review of the current knowledge on variant human genes that are directly implicated in human protection against oxidative stress is presented.

Molecular analysis of 9 new families with chronic granulomatous disease caused by mutations in CYBA, the gene encoding p22phox

Chronic granulomatous disease is a rare inherited disorder caused by nonexistent or severely decreased phagocyte superoxide production that results in a severe defect in host defense and consequent predisposition to microbial infection. The enzyme responsible for generating the superoxide, NADPH oxidase, involves at least 5 protein components. The absence of, or a defect in, any 1 of 4 of these proteins (p22phox, p47phox, p67phox, or gp91phox) gives rise to the known types of chronic granulomatous disease. One of the rarest forms of the disease is due to defects in the CYBA gene encoding p22phox, which together with gp91phox forms flavocytochromeb558, the catalytic core of NADPH oxidase. To date, only 9 kindreds with p22phoxdeficiency have been described in the literature comprising 10 mutant alleles. Four polymorphisms in the CYBA gene have also been reported. Here we describe 9 new, unrelated kindreds containing 12 mutations, 9 of which are novel. In addition, we report 3 new polymorphisms. The novel mutations are (a) deletion of exons 2 and 3, (b) a missense mutation in exon 3 (T155→C), (c) a splice site mutation at the 5′ end of intron 3, (d) a missense mutation in exon 2 (G74→T), (e) a nonsense mutation in exon 1 (G26→A), (f) a missense mutation in exon 4 (C268→T), (g) a frameshift in exon 3 due to the insertion of C at C162, (h) a nonsense mutation in exon 2 (G107→A), and (i) a missense mutation in exon 2 (G70→A).

Molecular analysis of 9 new families with chronic granulomatous disease caused by mutations in CYBA, the gene encoding p22phox

Chronic granulomatous disease is a rare inherited disorder caused by nonexistent or severely decreased phagocyte superoxide production that results in a severe defect in host defense and consequent predisposition to microbial infection. The enzyme responsible for generating the superoxide, NADPH oxidase, involves at least 5 protein components. The absence of, or a defect in, any 1 of 4 of these proteins (p22phox, p47phox, p67phox, or gp91phox) gives rise to the known types of chronic granulomatous disease. One of the rarest forms of the disease is due to defects in the CYBA gene encoding p22phox, which together with gp91phox forms flavocytochromeb558, the catalytic core of NADPH oxidase. To date, only 9 kindreds with p22phoxdeficiency have been described in the literature comprising 10 mutant alleles. Four polymorphisms in the CYBA gene have also been reported. Here we describe 9 new, unrelated kindreds containing 12 mutations, 9 of which are novel. In addition, we report 3 new polymorphisms. The novel mutations are (a) deletion of exons 2 and 3, (b) a missense mutation in exon 3 (T155→C), (c) a splice site mutation at the 5′ end of intron 3, (d) a missense mutation in exon 2 (G74→T), (e) a nonsense mutation in exon 1 (G26→A), (f) a missense mutation in exon 4 (C268→T), (g) a frameshift in exon 3 due to the insertion of C at C162, (h) a nonsense mutation in exon 2 (G107→A), and (i) a missense mutation in exon 2 (G70→A).

C242T polymorphism of NADPH oxidase p22 PHOX gene and ischemic cerebrovascular disease in the Japanese population

BACKGROUND AND PURPOSE

Superoxide has been implicated in the pathogenesis of ischemic stroke and atherosclerosis. NADPH oxidase, a major source of superoxide generation in neutrophils and the vascular system, plays a critical role in ischemic injury and atherogenesis. Recently, an association between the C242T polymorphism of p22 PHOX, an essential component of NADPH oxidase, and coronary artery disease (CAD) has been reported in several studies. To investigate the relationship between the C242T polymorphism of p22 PHOX and ischemic cerebrovascular disease (CVD), we conducted a case-control study.

METHODS

We recruited 226 CVD patients (atherothrombotic infarction, lacunar infarction, and transient ischemic attack) and 301 control subjects and analyzed C242T polymorphism of p22 PHOX by detection of restriction fragment length polymorphism.

RESULTS

The TC+TT genotype frequencies in the CVD group and control group were 21.7% and 13.3%, respectively, and the prevalence of the TC+TT genotype was significantly higher in the CVD patients (chi(2)=6.477, P=0.01, OR 1.81, 95% CI 1.15 to 2.86). Analysis by CVD subtypes showed that the OR for the TC+TT genotype was higher in the CVD patients with atherothrombotic infarction than in those with lacunar infarction and transient ischemic attack.

CONCLUSIONS

The C242T polymorphism of the NADPH oxidase p22 PHOX gene is a novel pathogenetic risk factor for CVD.