Relationship of the C242T p22phox gene polymorphism to angiographic coronary artery disease and endothelial function

A Case-Control Study of the Genetic Variability in Reactive Oxygen Species-Metabolizing Enzymes in Melanoma Risk

Recent studies have shown that ultraviolet (UV)-induced chemiexcitation of melanin fragments leads to DNA damage; and chemiexcitation of melanin fragments requires reactive oxygen species (ROS), as ROS excite an electron in the melanin fragments. In addition, ROS also cause DNA damages on their own. We hypothesized that ROS producing and metabolizing enzymes were major contributors in UV-driven melanomas. In this case-control study of 349 participants, we genotyped 23 prioritized single nucleotide polymorphisms (SNPs) in nicotinamide adenine dinucleotide phosphate (NADPH) oxidases 1 and 4 (NOX1 and NOX4, respectively), CYBA, RAC1, superoxide dismutases (SOD1, SOD2, and SOD3) and catalase (CAT), and analyzed their associated melanoma risk. Five SNPs, namely rs1049255 (CYBA), rs4673 (CYBA), rs10951982 (RAC1), rs8031 (SOD2), and rs2536512 (SOD3), exhibited significant genotypic frequency differences between melanoma cases and healthy controls. In simple logistic regression, RAC1 rs10951982 (odds ratio (OR) 8.98, 95% confidence interval (CI): 5.08 to 16.44; p < 0.001) reached universal significance (p = 0.002) and the minor alleles were associated with increased risk of melanoma. In contrast, minor alleles in SOD2 rs8031 (OR 0.16, 95% CI: 0.06 to 0.39; p < 0.001) and SOD3 rs2536512 (OR 0.08, 95% CI: 0.01 to 0.31; p = 0.001) were associated with reduced risk of melanoma. In multivariate logistic regression, RAC1 rs10951982 (OR 6.15, 95% CI: 2.98 to 13.41; p < 0.001) remained significantly associated with increased risk of melanoma. Our results highlighted the importance of RAC1, SOD2, and SOD3 variants in the risk of melanoma.

p22phox C242T gene polymorphism and overt diabetic nephropathy: a meta-analysis of 1,452 participants

BACKGROUND/AIMS

The p22phox C242T gene polymorphism (rs4673) may be linked to an increased susceptibility for overt diabetic nephropathy (ODN), but the study results are still inconclusive.

METHODS

To explore the relationship between p22phox C242T gene polymorphism and ODN, the current meta-analysis of 707 ODN patients and 745 controls from five individual studies was conducted. The pooled odds ratio (OR) and its corresponding 95% confidence interval (CI) were evaluated by either a random or fixed effect model.

RESULTS

In our meta-analysis, a significant relationship between the p22phox C242T gene polymorphism and ODN was found under allelic (OR, 2.760; 95% CI, 1.400 to 5.450; p = 0.004), recessive (OR, 5.080; 95% CI, 1.020 to 25.430; p = 0.05), dominant (OR, 1.700; 95% CI, 1.167 to 2.477; p = 0.006), homozygous (OR, 3.900; 95% CI, 1.022 to 14.889; p = 0.046), heterozygous (OR, 1.523; 95% CI, 1.167 to 1.986; p = 0.002), and additive genetic models (OR, 2.019; 95% CI, 1.232 to 3.309; p = 0.005).

CONCLUSIONS

A positive correlation between p22phox C242T gene polymorphism and ODN risk was found. The T allele carriers of p22phox C242T gene polymorphism might be predisposed to ODN.

RAGE and CYBA polymorphisms are associated with microalbuminuria and end-stage renal disease onset in a cohort of type 1 diabetes mellitus patients over a 20-year follow-up

AIMS

We investigated the association of polymorphisms of three genes implicated in oxidative stress: CYBA C242T, RAGE -374T/A and -429T/C, and ALOX12 Arg261Gln, with the delay of microalbuminuria onset in patients with type 1 diabetes mellitus (DT1).

METHODS

A total of 162 T1D patients presenting with diabetes for 32.9 ± 9 years were included in the study; 53 had persistent microalbuminuria (>30 mg/l) and 109 did not. Onset of diabetes, microalbuminuria and end-stage renal disease (ESRD) were recorded as bio-clinical data. We determined polymorphism association of microalbuminuria with a Cox regression model.

RESULTS

All polymorphisms respected the Hardy-Weinberg equilibrium. The Cox regression model validated four significant variables associated with microalbuminuria: RAGE 374AA (HR 4.19 [1.84-9.58] (p = 0.001)), CYBA TT+TC (HR 2.1 [1.16-3.80], p = 0.015), male sex (HR 1.92 [1.07-3.43], p = 0.028) and diabetes diagnosis at the pediatric stage (HR 1.85 [1.03-3.32], p = 0.039). The same association was found with ESRD (p = 0.028 and p = 0.033 for CYBA TC+TT and RAGE 374AA, respectively). CYBA C242T and RAGE 374T/A were not significantly associated with diabetic retinopathy.

CONCLUSIONS

CYBA C242T and RAGE -374T/A correlate with microalbuminuria onset in the French DT1 cohort. The same correlation with ESRD onset supports the argument for the involvement of a genetic predisposition involving kidney-specific oxidative stress for diabetic nephropathy.

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.

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.

Polymorphisms of genes in nitric oxide-forming pathway associated with ischemic stroke in Chinese Han population

AIM

To investigate the association of polymorphisms in four critical genes implicated in the NO-forming pathway with ischemic stroke (IS) in a Chinese Han population.

METHODS

DNA samples of 558 IS patients and 557 healthy controls from Chinese Han population were genotyped using the Taqman(TM) 7900HT Sequence Detection System. Six SNPs (rs841, rs1049255, rs2297518, rs1799983, rs2020744, rs4673) of the 4 related genes (eNOS, iNOS, GCH1, and CYBA) in the NO forming pathway were analyzed using the SPSS 13.0 software package for Windows.

RESULTS

One SNP located in the intron of GCH1 (rs841) was associated with IS independent of the traditional cardiovascular risk factors in co-dominant and dominant models (P=0.003, q=0.027; P=0.00006, q=0.0108; respectively). Moreover, the combination of rs1049255 CC+CT and rs841 GA+AA genotypes was associated with significantly higher risk for IS after adjustments (OR=1.73, 95% CI: 1.27-2.35, P<0.0001, q<0.0001).

CONCLUSION

The data suggest that genetic variants within the NO-forming pathway alter susceptibility to IS in Chinese Han population. Replication of the present results in other independent cohorts is warranted.

The C242T polymorphism of the p22-phox gene (CYBA) is associated with higher left ventricular mass in Brazilian hypertensive patients

BACKGROUND

Reactive oxygen species have been implicated in the physiopathogenesis of hypertensive end-organ damage. This study investigated the impact of the C242T polymorphism of the p22-phox gene (CYBA) on left ventricular structure in Brazilian hypertensive subjects.

METHODS

We cross-sectionally evaluated 561 patients from 2 independent centers [Campinas (n = 441) and Vitória (n = 120)] by clinical history, physical examination, anthropometry, analysis of metabolic and echocardiography parameters as well as p22-phox C242T polymorphism genotyping. In addition, NADPH-oxidase activity was quantified in peripheral mononuclear cells from a subgroup of Campinas sample.

RESULTS

Genotype frequencies in both samples were consistent with the Hardy- Weinberg equilibrium. Subjects with the T allele presented higher left ventricular mass/height2.7 than those carrying the CC genotype in Campinas (76.8 ± 1.6 vs 70.9 ± 1.4 g/m2.7; p = 0.009), and in Vitória (45.6 ± 1.9 vs 39.9 ± 1.4 g/m2.7; p = 0.023) samples. These results were confirmed by stepwise regression analyses adjusted for age, gender, blood pressure, metabolic variables and use of anti-hypertensive medications. In addition, increased NADPH-oxidase activity was detected in peripheral mononuclear cells from T allele carriers compared with CC genotype carriers (p = 0.03).

CONCLUSIONS

The T allele of the p22-phox C242T polymorphism is associated with higher left ventricular mass/height 2.7 and increased NADPH-oxidase activity in Brazilian hypertensive patients. These data suggest that genetic variation within NADPH-oxidase components may modulate left ventricular remodeling in subjects with systemic hypertension.

Exploring epistatic relationships of NO biosynthesis pathway genes in susceptibility to CHD

AIM

To assess the epistatic relationships of nitric oxide (NO) biosynthesis pathway genes in susceptibility to coronary heart disease (CHD).

METHODS

A total of 2142 subjects enrolled in two case-control studies was genotyped for 7 single-nucleotide polymorphisms (SNP) within NO biosynthesis pathway genes using TaqMan assays. The association analyses were performed at both SNP and haplotype levels. Two-way SNP-SNP interactions and high-order interactions were tested using multiple unconditional logistic regression analyses and generalized multifactor dimensionality reduction (GMDR) analyses, respectively.

RESULTS

Two alleles (rs1049255*C and rs841*A) were identified that were significantly associated with increased risk of CHD after adjusting for all confounders (OR=1.21, 95% CI: 1.06-1.39, combined P=0.001, P(corr)=0.007 and OR=1.30, 95% CI 1.12-1.50, combined P<0.001, P(corr)<0.001, respectively). Significant two-way SNP-SNP interactions were found between SNP rs2297518 and these two significant polymorphisms, affecting the risk of CHD (P<0.001 for both). No significant high-order interactions were identified.

CONCLUSION

The results suggested that two-way SNP-SNP interactions of polymorphisms within NO biosynthesis pathway genes contribute to CHD risk.

Homing endonucleases: from basics to therapeutic applications

Homing endonucleases (HE) are double-stranded DNAses that target large recognition sites (12-40 bp). HE-encoding sequences are usually embedded in either introns or inteins. Their recognition sites are extremely rare, with none or only a few of these sites present in a mammalian-sized genome. However, these enzymes, unlike standard restriction endonucleases, tolerate some sequence degeneracy within their recognition sequence. Several members of this enzyme family have been used as templates to engineer tools to cleave DNA sequences that differ from their original wild-type targets. These custom HEs can be used to stimulate double-strand break homologous recombination in cells, to induce the repair of defective genes with very low toxicity levels. The use of tailored HEs opens up new possibilities for gene therapy in patients with monogenic diseases that can be treated ex vivo. This review provides an overview of recent advances in this field.

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.

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.

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.

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.

Impact of NAD(P)H oxidase p22 phox gene polymorphism on vascular aging in Korean centenarian and nonagenarian

BACKGROUND

Oxidative stress, the imbalance between production and removal of reactive oxygen species (ROS), is implicated in the process of cardiovascular aging. Membrane-associated NAD(P)H oxidase system is the most important source of ROS in vascular cells. p22(phox), a critical component of the NAD(P)H oxidase, has a polymorphic site on exon 4, associated with variable enzyme activity. The goal of this study is to investigate the effect of the p22(phox) C242T polymorphism on cardiovascular aging.

METHODS

We investigated, in a cross-sectional study, the distribution of the p22(phox) genotypes and its impact on vascular aging in elderly Korean subjects (N=123, mean age+/-SD: 97.0+/-5.0). p22(phox) C242T polymorphism was determined by PCR and restriction fragment length polymorphism analysis. The p22(phox) genotype and allele frequencies were also compared with younger Korean subjects (N=363, mean age+/-SD: 49.0+/-10.3).

RESULTS

No significant difference was identified in p22(phox) genotype frequency according to the subject's age. However, the prevalence of CT+TT genotype was significantly less frequent in normotensive extremely elderly compared with younger subjects. Furthermore, the prevalence of the CT+TT genotype was significantly more frequent in hypertensive subjects (21.9%) than in the normotensive group (6.0%, P=0.016) in extremely elderly subject. The association was more significant in systolic hypertension rather than diastolic hypertension. Mean systolic blood pressure and pulse pressure were also significantly higher in subjects with CT+TT genotype. In contrast, there was no significant association between p22(phox) genotype and hypertension in younger-aged group.

CONCLUSION

These results suggest an association between the p22(phox) C242T polymorphism and vascular aging, which might be mediated by the increase of oxidative stress.

Genetic markers of oxidative stress and coronary atherosclerosis

Atherosclerosis, the primary cause of coronary artery disease (CAD), is a multifactorial disease, the molecular etiology of which involves interaction of many genes and environmental factors. Reactive oxygen species are integral to many cellular and biomolecular processes that are active in the transition of incipient fatty streaks into acute coronary syndromes. Animal models of atherosclerosis and correlative data from human studies support the oxidative stress hypothesis of atherosclerosis. However, the association of genetic polymorphisms that underlie enhanced oxidative stress with CAD is controversial. In this review, we discuss polymorphisms in genes that are main sources of reactive oxygen species generation (NADH oxidase, endothelial nitric oxide synthase, and myeloperoxidase) in mitochondria and the antioxidant enzymes paraoxonase, glutathione reductase, and heme oxygenase. The contribution of defined genetic variants involved in oxidative homeostasis to human atherosclerosis susceptibility is modest because regulation of oxidative stress is multifactorial. However, the contribution of genetic haplotypes in concert with environmental factors is likely significant. A more rigorous characterization of genetic and oxidative phenotypes together with characterization of novel gene polymorphisms may help in early therapeutic intervention for CAD.

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 Enzymopathies and Vascular Disease

In the vasculature, reactive oxygen species (ROS) generated by both mitochondrial respiration and enzymatic sources serve as integral components of cellular signaling and homeostatic mechanisms. Because ROS are highly reactive biomolecules, the cellular redox milieu is carefully maintained by small-molecule antioxidants and antioxidant enzymes to prevent the deleterious consequences of ROS excess. When this redox balance is perturbed, because of either increased ROS production or decreased antioxidant capacity, oxidant stress is increased in the vessel wall and, if not offset, vascular dysfunction ensues. A number of heritable polymorphisms of pro-oxidant enzymes, including 5-lipoxygenase, cyclooxygenase-2, nitric oxide synthase-3, and NAD(P)H oxidase, have been identified and found to modulate ROS production and, thereby, the risk of atherothrombotic cardiovascular disease in individuals with these genetic polymorphisms. Similarly, heritable deficiency of the antioxidant enzymes catalase, glutathione peroxidases, glutathione- S -transferases, heme oxygenase, and glucose-6-phosphate dehydrogenase favors ROS accumulation, and has been associated with an increased risk of vascular disease. Individually, each of these polymorphisms imposes a state of uncompensated oxidant stress on the vasculature and collectively comprise the oxidative enzymopathies.

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.

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.

Lack of evidence for association of high altitude pulmonary edema and polymorphisms of the NO pathway

One essential factor in the development of high altitude pulmonary edema (HAPE) is elevated pulmonary artery pressure, possibly due to a lack of nitric oxide (NO) in pulmonary vessels. NOS3 gene polymorphisms (G894T, T-786C, and CA-repeats > or =38) might be linked to decreased NO synthesis and increased susceptibility to HAPE, while the C242T polymorphism of the CYBA gene [encoding for the NAD(P)H oxidase subunit p22phox] may increase NO availability and thus convey resistance to HAPE. To test this hypothesis, we genotyped 51 mountaineers susceptible and 52 mountaineers not susceptible to HAPE. Genotyping revealed similar genotype frequencies of the G894T and the T-786C NOS3 polymorphism in both groups (G894T: susceptibles, 39.2% GG, 47.1% GT, 13.7% TT; nonsusceptibles, 48.0% GG, 44.0% GT, 8.0% TT; p = 0.54. T-786C: susceptibles, 45.1% TT, 39.2% TC, 15.7% CC; nonsusceptibles, 53.8% TT, 40.4% TC, 5.8% CC; p = 0.28). Genotype frequencies of the C242T CYBA polymorphism were 43.1% CC, 47.1 % CT, and 9.8% TT in HAPE susceptibles and 38.0% CC, 52.0 % CT, and 10.0% TT (p = 0.92) in nonsusceptibles. There was also no difference between the two groups in the number of CA repeats (p = 0.57), and individuals with > or =38 CA repeats were not more likely to develop HAPE (p = 1.0). Haplotype analysis for the NOS3 polymorphisms also revealed no association with HAPE. The results of this study suggest that none of these genetic variants plays a substantial role in the pathogenesis of HAPE in Caucasians, but does not exclude epistatic effects that might still involve the genetic systems studied here.

Polymorphisms of the NADPH oxidase P22PHOX gene in a Caucasian population with intracranial aneurysms

BACKGROUND

Vascular remodeling generated by reactive oxygen species contributes to aneurysm formation. The NADPH oxidase system is a major source of superoxide anion not only in phagocytes, but also in endothelial and vascular smooth muscle cells. Polymorphisms of p22phox, an essential component of the NADPH oxidase system, are found to be associated with atherosclerosis, while a recent study found a significant association between the 214C>T polymorphism and the occurrence of ischemic cerebrovascular disease. We conducted a case-control study to investigate the relationship of five polymorphisms of the P22PHOX gene and the occurrence of cerebral aneurysms.

METHODS

The study population consisted of 113 patients with intracranial aneurysms and 53 control subjects. The 214C>T polymorphism was investigated by restriction fragment length polymorphism analysis, while polymorphisms 381T>C, 480G>A, 521C>T, and *24A>G were analyzed by direct sequencing of exon 6 and adjacent intronic sequences.

RESULTS

The analysis of a primary study sample comprising 35 cases and 28 controls failed to show a significant association between any of the five polymorphisms and the occurrence of intracranial aneurysms using both allele frequencies and genotypes (all nominal p > 0.05). Although there was a deviation from Hardy-Weinberg equilibrium in cases at the 521C>T locus (nominal p < 0.05), this could not be confirmed in a second study sample of 78 patients. Haplotypes were constructed regarding three frequent polymorphisms (214C>T, 521C>T, and *24A>G); haplotype frequencies in cases and controls were not significantly different.

CONCLUSION

Although polymorphisms of the P22PHOX gene located in the coding region and the 3'-untranslated region were reported to be associated with atherosclerosis and cerebrovascular disease, our data provide evidence that there is no association between these polymorphisms and the occurrence of cerebral aneurysms in Caucasians.

NAD(P)H oxidase p22phox Gene C242T polymorphism and lipoprotein oxidation

BACKGROUND

Vascular NAD(P)H oxidase is a key enzyme of superoxide anion production in human vessel walls. The C242T mutation in the CYBA gene coding for p22phox, a component of the enzyme, may change the redox state. The aim of this study was to evaluate the influence of the polymorphism on serum concentrations of oxidative stress markers.

METHODS

Serum samples were collected from 134 Type 2 diabetic patients and analyzed for oxidized high-density lipoprotein (HDL) by in-house ELISA, and oxidized low-density lipoprotein (LDL) and thiobarbituric acid reactive substance (TBARS) by commercial kits. For genotyping, the Taqman PCR method was adapted to detect the polymorphism.

RESULTS

Circulating concentrations of oxidized HDL were about 1.5-fold lower in those of the CT/TT genotypes than the CC genotype [3.3 +/- 0.3 and 5.0 +/- 0.3 U/dl (mean +/- S.E.M.), respectively; multiple regression analysis, p=0.006], whereas concentrations of oxidized LDL were slightly greater (1.1-fold, p=0.01) in those with the CT/TT genotypes. However, no significant difference was observed in TBARS between the genotypes.

CONCLUSIONS

The effect was inconsistent among the markers, but these results suggest that the CYBA C242T polymorphism is involved in NAD(P)H oxidase activity and affects oxidation of lipoproteins by altering the redox state in the vasculature.

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.

The C242T-polymorphism of the NADPH/NADH oxidase gene p22phox subunit is not associated with pre-eclampsia

Pre-eclampsia is a pregnancy-related multisystem disorder characterised by elevation of blood pressure and proteinuria, in which oxidative stress may play an important role. Blood pressure is partly controlled by O(-)(2) production by NADPH/NADH oxidase and recently it was shown that a C242T substitution in the p22phox gene was associated with coronary artery disease, in which elevated blood pressure and oxidative stress are also important pathophysiologic features. Therefore we studied the prevalence of the C242T polymorphism in the NADPH/NADH oxidase gene in women with pre-eclampsia and/or haemolysis, elevated liver enzymes and low platelets (HELLP) syndrome as compared with women with a normotensive pregnancy. DNA from control women (n = 78), women with pre-eclampsia (n = 40), HELLP syndrome (n = 9) or women with HELLP complicated by pregnancy-induced hypertension or pre-eclampsia (n = 46) were tested for the presence of the C242T polymorphism by polymerase chain reaction followed by restriction fragment-length polymorphism. The prevalence of the homozygous CC-genotype was similar in the patient groups compared with controls. The allele frequency of the T-allele was 31% in both control and patient groups. In conclusion the C242T polymorphism in the p22phox subunit of the NADPH/NADH oxidase gene is not associated with pre-eclampsia. Therefore, oxidative stress generated by NADPH/NADH oxidase probably does not play a role in the development of pre-eclampsia.

Rapid detection of polymorphisms of the nitric oxide cascade

NOS3 (endothelial nitric oxide (NO) synthase) and p22phox (subunit of NAD(P)H oxidase) are two genes whose products are involved in formation and degradation of NO, a ubiquitous signaling molecule largely responsible for the maintenance of normal endothelial function. The G894T polymorphism of NOS3 and the C242T polymorphism of p22phox are reportedly associated with numerous cardiovascular diseases. For each polymorphism we developed a rapid and reliable method with the hybridization probes format on the LightCycler and compared it with conventional PCR-restriction fragment length polymorphism (PCR-RFLP) analysis with regard to reliability, duration and cost. The new methods are more reliable, faster and less expensive than PCR-RFLP analysis and therefore represent a significant advantage in the detection of two candidate risk factors for cardiovascular diseases.

Association between polymorphism in the chemokine receptor CX3CR1 and coronary vascular endothelial dysfunction and atherosclerosis

Fractalkine, a chemokine expressed by inflamed endothelium, induces leukocyte adhesion and migration via the receptor CX3CR1, and the CX3CR1 polymorphism V249I affects receptor expression and function. Here we show that this polymorphism is an independent risk factor for atherosclerotic coronary artery disease (CAD). Genotyping of the CX3CR1-V249I polymorphism was performed in a cohort of 339 white individuals who underwent cardiac catheterization (n=197 with and n=142 without CAD, respectively). In 203 patients, intracoronary acetylcholine 15 microg/min) and sodium nitroprusside (20 microg/min) were administered to test endothelium-dependent and -independent coronary vascular function, respectively. Change in coronary vascular resistance (DeltaCVR) was measured as an index of microvascular dilation. An association was observed between presence of the CX3CR1 I249 allele and reduced prevalence of CAD, independent of established CAD risk factors (odds ratio=0.54 [95% confidence interval, 0.30 to 0.96], P=0.03). Angiographic severity of CAD was also lower in these subjects (P=0.01). Furthermore, endothelium-dependent vasodilation was greater in these individuals compared with individuals homozygous for the CX3CR1-V249 allele (DeltaCVR during acetylcholine = -46+/-3% versus -36+/-3%, respectively, P=0.02), whereas DeltaCVR with sodium nitroprusside was similar in both groups (-55+/-2% versus -53+/-2%, P=0.45). The association between CX3CR1 genotype and endothelial function was independent of established risk factors and presence of CAD by multivariate analysis (P=0.02). Thus, the CX3CR1 I249 allele is associated with decreased risk of CAD and improved endothelium-dependent vasodilation. This suggests that CX3CR1 may be involved in the pathogenesis of CAD.

Functional effect of the C242T polymorphism in the NAD(P)H oxidase p22phox gene on vascular superoxide production in atherosclerosis

BACKGROUND

Increased superoxide anion production increases oxidative stress and reduces nitric oxide bioactivity in vascular disease states. NAD(P)H oxidase is an important source of superoxide in human blood vessels, and some studies suggest a possible association between polymorphisms in the NAD(P)H oxidase CYBA gene and atherosclerosis; however, no functional data address this hypothesis. We examined the relationships between the CYBA C242T polymorphism and direct measurements of superoxide production in human blood vessels.

METHODS AND RESULTS

Vascular NAD(P)H oxidase activity was determined in human saphenous veins obtained from 110 patients with coronary artery disease and identified risk factors. Immunoblotting, reverse-transcription polymerase chain reaction, and DNA sequencing showed that p22phox protein, mRNA, and 242C/T allelic variants are expressed in human blood vessels. Vascular superoxide production, both basal and NADH-stimulated, was highly variable between patients, but the presence of the CYBA 242T allele was associated with significantly reduced vascular NAD(P)H oxidase activity, independent of other clinical risk factors for atherosclerosis.

CONCLUSIONS

Association of the CYBA 242T allele with reduced NAD(P)H oxidase activity in human blood vessels suggests that genetic variation in NAD(P)H oxidase components may play a significant role in modulating superoxide production in human atherosclerosis.

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.