Functional Effect of the p22 phox −930 A/G Polymorphism on p22 phox Expression and NADPH Oxidase Activity in Hypertension

Molecular Genetics of Abnormal Redox Homeostasis in Type 2 Diabetes Mellitus

Numerous studies have shown that oxidative stress resulting from an imbalance between the production of free radicals and their neutralization by antioxidant enzymes is one of the major pathological disorders underlying the development and progression of type 2 diabetes (T2D). The present review summarizes the current state of the art advances in understanding the role of abnormal redox homeostasis in the molecular mechanisms of T2D and provides comprehensive information on the characteristics and biological functions of antioxidant and oxidative enzymes, as well as discusses genetic studies conducted so far in order to investigate the contribution of polymorphisms in genes encoding redox state-regulating enzymes to the disease pathogenesis.

Oxidative Regulation of Vascular Cav1.2 Channels Triggers Vascular Dysfunction in Hypertension-Related Disorders

Blood pressure is determined by cardiac output and peripheral vascular resistance. The L-type voltage-gated Ca²⁺ (Ca_v1.2) channel in small arteries and arterioles plays an essential role in regulating Ca²⁺ influx, vascular resistance, and blood pressure. Hypertension and preeclampsia are characterized by high blood pressure. In addition, diabetes has a high prevalence of hypertension. The etiology of these disorders remains elusive, involving the complex interplay of environmental and genetic factors. Common to these disorders are oxidative stress and vascular dysfunction. Reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) and mitochondria are primary sources of vascular oxidative stress, whereas dysfunction of the Ca_v1.2 channel confers increased vascular resistance in hypertension. This review will discuss the importance of ROS derived from NOXs and mitochondria in regulating vascular Ca_v1.2 and potential roles of ROS-mediated Ca_v1.2 dysfunction in aberrant vascular function in hypertension, diabetes, and preeclampsia.

Oxidative Stress and Vascular Damage in the Context of Obesity: The Hidden Guest

The vascular system plays a central role in the transport of cells, oxygen and nutrients between different regions of the body, depending on the needs, as well as of metabolic waste products for their elimination. While the structure of different components of the vascular system varies, these structures, especially those of main arteries and arterioles, can be affected by the presence of different cardiovascular risk factors, including obesity. This vascular remodeling is mainly characterized by a thickening of the media layer as a consequence of changes in smooth muscle cells or excessive fibrosis accumulation. These vascular changes associated with obesity can trigger functional alterations, with endothelial dysfunction and vascular stiffness being especially common features of obese vessels. These changes can also lead to impaired tissue perfusion that may affect multiple tissues and organs. In this review, we focus on the role played by perivascular adipose tissue, the activation of the renin-angiotensin-aldosterone system and endoplasmic reticulum stress in the vascular dysfunction associated with obesity. In addition, the participation of oxidative stress in this vascular damage, which can be produced in the perivascular adipose tissue as well as in other components of the vascular wall, is updated.

Association of Genes Related to Oxidative Stress with the Extent of Coronary Atherosclerosis

Oxidative stress is believed to play a critical role in atherosclerosis initiation and progression. In line with this, in a group of 1099 subjects, we determined eight single nucleotide polymorphisms (SNPs) related to oxidative stress (PON1 c.575A>G, MPO c.−463G>A, SOD2 c.47T>C, GCLM c.−590C>T, NOS3 c.894G>T, NOS3 c.−786T>C, CYBA c.214C>T, and CYBA c.−932A>G) and assessed the extent of atherosclerosis in coronary arteries based on Gensini score. An increased risk of having a Gensini score in the higher half of the distribution was observed for the PON1 c.575G allele (odds ratio (OR) = 1.27, 95% confidence interval (CI): 1.004–1.617, p = 0.046). Next, the genetic risk score (GRS) for the additive effect of the total number of pro-oxidative alleles was assessed. We noted an increase in the risk of having a Gensini score above the median with the maximum number of risk alleles (OR = 2.47, 95% CI: 1.19–5.23, p = 0.014). A univariate Spearman’s test revealed significant correlation between the total number of pro-oxidant alleles (GRS) and the Gensini score (ρ = 0.068, p = 0.03). In conclusion, the PON1 c.575A>G variant and the high number of risk alleles (GRS) were independent risk factors for a high Gensini score. We suggest, however, that GRS might occur as a more valuable component in adding a predictive value to the genetic background of atherosclerosis.

Association of CYBA gene (-930 A/G and 242 C/T) polymorphisms with oxidative stress in breast cancer: a case-control study

Background

Oxidative stress (OS) is a key characteristic feature in cancer initiation and progression. Among multiple cancers, NADPH oxidase (NOX) dependent free radical production is implicated in oxidative stress. P22phox, a subunit of NADPH oxidase encoded by the CYBA gene has functional polymorphisms associated with various complex diseases. The present study was aimed to examine the importance and association of the functional polymorphisms of CYBA gene (-930 A/G and 242 C/T) with the oxidative stress in breast cancer (BC) development and progression.

Materials and Methods

We have performed a case-control study on 300 breast cancer patients and 300 healthy individuals as controls to examine the role of CYBA gene -930 A/G and 242 C/T single nucleotide polymorphisms (SNPs) using As-PCR and PCR-RFLP assays and its association with OS as measured by plasma MDA levels. Linkage disequilibrium (LD) plots were generated using Haploviewtool and Multifactor dimensionality reduction (MDR) analysis was applied to assess high-order interactions between the SNPs. The Insilco analysis has been performed to predict the effect of SNPs on the gene regulation using online tools.

Results

We have found that genotype frequencies of CYBA gene -930 A/G and 242C/T polymorphism were significantly different between controls and BC patients (p < 0.05). The haplotype combination -930G/242C and -930G/242T were associated with 1.44 & 1.56 folds increased risk for breast cancer respectively. Further, the MDA levels were higher in the patients carrying -930G/242C and -930G/242T haplotype (p < 0.001). Our results have been substantiated by Insilco analysis.

Conclusion

Results of the present study suggest that GG genotype of -930 A/G polymorphism, -930G/242C and -930G/242T haplotypes of CYBA gene polymorphisms have shown association with higher MDA levels in breast cancer patients, signify that elevated oxidative stress might aid in increased risk for breast cancer initiation and progression.

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.

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

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

Allelic variations in the CYBA gene of NADPH oxidase and risk of kidney complications in patients with type 1 diabetes

Oxidative stress plays a pivotal role in the pathophysiology of diabetic nephropathy, and the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system is an important source of reactive oxygen species in hyperglycemic conditions in the kidney. Plasma concentration of advanced oxidation protein products (AOPP), a marker of oxidative stress, is increased in patients with diabetic nephropathy. We investigated associations of variants in the CYBA gene, encoding the regulatory subunit p22(phox) of NADPH oxidase, with diabetic nephropathy and plasma AOPP and myeloperoxidase (MPO) concentrations in type 1 diabetic patients. Seven SNPs in the CYBA region were analyzed in 1357 Caucasian subjects with type 1 diabetes from the SURGENE (n=340), GENEDIAB (n=444), and GENESIS (n=573) cohorts. Duration of follow-up was 10, 9, and 6 years, respectively. Cox proportional hazards and logistic regression analyses were used to estimate hazard ratios (HR) or odds ratios (OR) for incidence and prevalence of diabetic nephropathy. The major G-allele of rs9932581 was associated with the incidence of renal events defined as new cases of microalbuminuria or the progression to a more severe stage of nephropathy during follow-up (HR 1.59, 95% CI 1.17-2.18, P=0.003) in SURGENE. The same allele was associated with established/advanced nephropathy (OR 1.52, 95% CI 1.22-1.92, P=0.0001) and with the incidence of end-stage renal disease (ESRD) (HR 2.01, 95% CI 1.30-3.24, P=0.001) in GENEDIAB/GENESIS pooled studies. The risk allele was also associated with higher plasma AOPP concentration in subsets of SURGENE and GENEDIAB, with higher plasma MPO concentration in a subset of GENEDIAB, and with lower estimated glomerular filtration rate (eGFR) in the three cohorts. In conclusion, a functional variant in the promoter of the CYBA gene was associated with lower eGFR and with prevalence and incidence of diabetic nephropathy and ESRD in type 1 diabetic patients. These results are consistent with a role for NADPH oxidase in the pathophysiology of kidney complications of diabetes.

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.

Regulation of Nox enzymes expression in vascular pathophysiology: Focusing on transcription factors and epigenetic mechanisms

NADPH oxidases (Nox) represent a family of hetero-oligomeric enzymes whose exclusive biological function is the generation of reactive oxygen species (ROS). Nox-derived ROS are essential modulators of signal transduction pathways that control key physiological activities such as cell growth, proliferation, migration, differentiation, and apoptosis, immune responses, and biochemical pathways. Enhanced formation of Nox-derived ROS, which is generally associated with the up-regulation of different Nox subtypes, has been established in various pathologies, namely cardiovascular diseases, diabetes, obesity, cancer, and neurodegeneration. The detrimental effects of Nox-derived ROS are related to alterations in cell signalling and/or direct irreversible oxidative damage of nucleic acids, proteins, carbohydrates, and lipids. Thus, understanding of transcriptional regulation mechanisms of Nox enzymes have been extensively investigated in an attempt to find ways to counteract the excessive formation of Nox-derived ROS in various pathological states. Despite the numerous existing data, the molecular pathways responsible for Nox up-regulation are not completely understood. This review article summarizes some of the recent advances and concepts related to the regulation of Nox expression in the vascular pathophysiology. It highlights the role of transcription factors and epigenetic mechanisms in this process. Identification of the signalling molecules involved in Nox up-regulation, which is associated with the onset and development of cardiovascular dysfunction may contribute to the development of novel strategies for the treatment of cardiovascular diseases.

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Nox is a unique class of enzymes whose sole function is the generation of ROS.

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Nox-derived ROS play a major role in cell physiology.

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Enhanced expression and activation of Nox has been reported in numerous pathologies.

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Nox expression is regulated via complex transcription factor-epigenetic mechanisms.

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Understanding of Nox regulation is essential to counteract ROS-induced cell damage.

CYBA (p22phox) variants associate with blood pressure and oxidative stress markers in hypertension: a replication study in populations of diverse altitudes

CYBA (p22(phox)) is an integral constituent of the NADPH oxidases and is consequently a main component of oxidative stress, which is strongly associated with hypertension. This study investigates the contribution of CYBA polymorphisms toward the complex etiology of hypertension in two ethnically different populations, one located at a high altitude and the other at a low altitude. The significance of CYBA single nucleotide polymorphisms and their correlation with clinical and biochemical phenotypes were investigated in age- and ethnicity-matched unrelated permanent high-altitude residents (>3500 m) comprising 245 controls and 241 patients. The results were replicated in a second population comprising 935 controls and 545 patients who lived at a low altitude (<200 m). The analysis of covariance revealed that CYBA risk alleles and their haplotypes, rs8854A/rs9932581G/rs4873C and rs8854G/rs9932581G/rs4873C, were positively correlated with clinical parameters, for example, systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP), and biochemical parameters, for example, 8-isoPGF2α level, and inversely correlated with catalase activity in patients compared with controls (P⩽0.01, each). Conversely, the protective alleles and their haplotype, rs8854G/rs9932581A/rs4873T, were inversely correlated with SBP, DBP, MAP and 8-isoPGF2α level, and positively correlated with catalase activity (P⩽0.001, each). Furthermore, correlation analysis between the clinical and biochemical parameters revealed a positive correlation of SBP, DBP and MAP with 8-isoPGF2α levels and a negative correlation with catalase activity in both populations (P<0.0001, each). CYBA (p22(phox)) variants influence the markers of oxidative stress and are associated with hypertension.

Association between the nicotinamide adenine dinucleotide phosphate oxidase p22phox gene -A930G polymorphism and intracerebral hemorrhage

The present study aimed to evaluate whether the ‑A930G polymorphism of the nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase p22phox gene is involved in intracerebral hemorrhage (ICH) in the Chinese Han population. In the present case‑control investigation, the subjects included 118 patients with ICH and 147 healthy controls. The ‑A930G polymorphism was determined using polymerase chain reaction and restriction fragment length polymorphism. Furthermore, the correlation between the ‑A930G gene polymorphism and ICH was evaluated using statistical analyses. The distribution of p22phox ‑A930G genotypes differed significantly between the two groups (P=0.003), with the AA, AG and GG genotype frequencies being 61.9, 29.3 and 8.8% in the control group and 40.7, 45.8 and 13.6% in the ICH group, respectively. The G allele frequency was significantly higher in patients with ICH compared with healthy controls (36.4 vs. 23.5%; P<0.05), however, the opposite was observed in the frequency of the A allele (63.6 vs. 76.5%; P<0.05). Binary logistic regression analysis revealed that genetic mutations of the p22phox ‑A930G gene were independent risk factors of ICH (odds ratio, 2.196; 95% confidence interval, 1.003‑4.586; P=0.009). In addition, certain conventional factors were associated with increased risk of ICH, including elevated blood pressure, increased levels of glucose and triglycerides in the blood, a history of hypertension and smoking. The ‑A930G polymorphism of the p22phox gene may affect the susceptibility to ICH and certain haplotypes of the gene may be associated with a higher susceptibility to ICH.

C3F gene mutation is involved in the susceptibility to pre-eclampsia

OBJECTIVE

The aim of this study was to analyze the functional polymorphism of exon 3 of the gene of complement component C3 (rs 2230199) to identify the potential involvement of the mutated gene C3F in the genesis of pre-eclampsia.

MATERIEL AND METHODS

It is a comparative case-control study conducted in the university center of maternity and neonatology of Monastir with collaboration of high institute of biotechnology (Tunisia) on a period of 2 years. Two hundred and fifty patients and 96 newborns divided into pre-eclampsia group (150 parturients with pre-eclampsia and 48 newborns) and control group (100 parturients with normal pregnancy and their 48 infants) are taken. Each patient and control were sampled for the phenotypic study and the molecular analysis. The ARMS-PCR (amplification refractory mutation system) was the standard procedure in our study. A simple observation let to distinguish three cases of genotypes: SS, FF and SF.

RESULTS

In the control group, 56% of parturients had the genotype SS, 38%, the genotype SF and 6%, FF genotype. In the pre-eclamptic population, SS, SF, and FF genotypes were determined, respectively, 40, 45.30 and 14.60% of the patients. There is a sharp increase in the frequency of the FF genotype in pre-eclamptic patients compared to controls (14.60 vs. 6%). The difference was statistically significant (p = 0.01). The frequencies of C3S and alleles C3F determined in controls (respectively, 74 and 26%) were different from those identified in pre-eclamptic patients (respectively, 62.60 and 37.30%). This difference was statistically significant (p = 0.005). The C3S and C3F allele frequencies determined in control newborns (respectively, 83.33 and 16.66%) were slightly different from those identified in newborn issued from pre-eclamptic patients (respectively, 80.2 and 19.79%), but the difference was not statistically significant (p = 0.67).

CONCLUSION

The gene polymorphism of complement component C3 was significantly associated with the onset of pre-eclampsia. These results should be confirmed by other studies looking at larger scale to consider this gene as a new biomarker with predictive potential therapeutic consequences.

The antioxidant activity of soursop decreases the expression of a member of the NADPH oxidase family

Cellular oxidative stress produced by an increase in free radicals is one of the factors that promote the development of chronic degenerative diseases; therefore, consuming natural antioxidants helps minimize their negative effects. This study evaluated the cytotoxicity of the soursop extract (Annona muricata), its cytoprotective capacity against oxidative stress induced by hydrogen peroxide, the inhibitory potential of reactive oxygen species (ROS), the molecular mechanism of its antioxidant action, and its capacity to repair cellular damage in the fibroblast cell line. The soursop extract proved not to be cytotoxic in fibroblast cultures and showed cytoprotective capacity against hydrogen peroxide-induced stress; in cell culture it reduced the generation of ROS significantly by inhibiting a sub-unit of the NADPH oxidase enzyme (p47phox). The soursop extract can prevent damage caused by cellular oxidants.

Genetics of oxidative stress in obesity

Obesity is a multifactorial disease characterized by the excessive accumulation of fat in adipose tissue and peripheral organs. Its derived metabolic complications are mediated by the associated oxidative stress, inflammation and hypoxia. Oxidative stress is due to the excessive production of reactive oxygen species or diminished antioxidant defenses. Genetic variants, such as single nucleotide polymorphisms in antioxidant defense system genes, could alter the efficacy of these enzymes and, ultimately, the risk of obesity; thus, studies investigating the role of genetic variations in genes related to oxidative stress could be useful for better understanding the etiology of obesity and its metabolic complications. The lack of existing literature reviews in this field encouraged us to gather the findings from studies focusing on the impact of single nucleotide polymorphisms in antioxidant enzymes, oxidative stress-producing systems and transcription factor genes concerning their association with obesity risk and its phenotypes. In the future, the characterization of these single nucleotide polymorphisms (SNPs) in obese patients could contribute to the development of controlled antioxidant therapies potentially beneficial for the treatment of obesity-derived metabolic complications.

The -930A>G polymorphism of the CYBA gene is associated with premature coronary artery disease. A case-control study and gene-risk factors interactions

Reactive oxygen species (ROS) are involved in the pathogenesis of atherosclerosis and coronary artery disease (CAD). NADPH oxidases are the main source of ROS in the vasculature. p22phox is a critical component of vascular NADPH oxidases and is encoded by the CYBA (cytochrome b₂₄₅ alpha) gene. The −930A>G CYBA polymorphism (rs9932581:A>G) modulates the activity of the CYBA promoter, and influences CYBA transcriptional activity. The aim of the present study was to analyze a possible association between the −930A>G polymorphism and CAD and to search for gene–traditional risk factors interactions. 480 subjects were studied: 240 patients with premature CAD, 240 age and sex matched blood donors. The −930A>G polymorphism was genotyped using the TaqMan^® Pre-designed SNP Genotyping Assay (Applied Biosystems). The −930G allele carrier state was a risk factor for CAD (OR 2.03, 95 % CI 1.21–3.44, P = 0.007). A synergistic effect of the −930G allele with overweight/obesity (BMI ≥ 25) and cigarette smoking was found. The estimated CAD risk for BMI ≥ 25 and the −930G allele interaction was about 160 % greater than that predicted by assuming additivity of the effects, and about 40 % greater for interaction of cigarette smoking and the −930G allele. Overweight/obesity was a risk factor for CAD only in the −930G allele carriers (P < 10⁻¹⁰) but not in the AA homozygotes (P = 1.00). In conclusion the −930A>G CYBA polymorphism is associated with CAD in the Polish population. The −930G allele carriers are particularly at risk of consequences of obesity and tobacco smoke exposure.

PPARδ activation inhibits homocysteine-induced p22(phox) expression in EA.hy926 cells through reactive oxygen species/p38MAPK pathway

Increased expression of the p22(phox) subunit of the NADPH oxidase complex may possibly contribute to both the enzyme׳s increased activation and the occurrence of oxidative stress during hyperhomocysteinaemia. However, the activation of peroxisome proliferator-activated receptor (PPAR) δ has been shown to inhibit p22(phox) expression. The purpose of this study was to elucidate the signaling pathway by which PPARδ activation regulated homocysteine-induced expression of p22(phox). EA.hy926 cells were stimulated with homocysteine (Hcy) in the presence or absence of the PPARδ-specific agonist, GW0742, or of various signaling inhibitors, including the antioxidants N-acetylcysteine (NAC), NADPH oxidase inhibitor, diphenyleneiodonium (DPI), and the p38MAPK inhibitor, SB203580. Expression of p22(phox) mRNA and phospho-p38MAPK protein were measured by real-time PCR and western blot analysis, respectively, and reactive oxygen species were measured by fluorescence microscopy. Our data indicate that Hcy increased both the expression of p22(phox) in a concentration-dependent manner and also increased phosphoryation of p38 MAPK and reactive oxygen species production in a time-dependent manner. However, activation of the PPARδ signaling pathway by the agonist GW0742 reversed all these changes induced by Hcy. Furthermore, SB203580 prevented the increase in p22(phox) expression, and NAC and DPI not only inhibited Hcy-induced phosphorylation of p38MAPK, but also prevented expression of p22(phox). These findings indicate that Hcy-induced expression of p22(phox) is regulated by the reactive oxygen species/p38MAPK pathway and that PPARδ activation is capable of attenuating this pathway by eliminating Hcy-induced reactive oxygen species production.

Association of NADPH oxidase p22phox gene C242T, A640G and -930A/G polymorphisms with primary knee osteoarthritis in the Greek population

Osteoarthritis (OA) is the most common form of arthritis with still unknown pathogenic etiology and considerable contribution of genetic factors. Recently, a new emerging role of oxidative stress in the pathology of OA has been reported, lacking however elucidation of the underlying mechanism. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase being a complex enzyme produced by chondrocytes, presents the major source of reactive oxygen species and main contributor of increased oxidative stress. The present study aims to evaluate the association of NADPH oxidase p22phox gene C242T, A640G and -A930G polymorphisms with primary knee OA in the Greek population. One hundred fifty five patients with primary symptomatic knee OA participated in the study along with 139 matched controls. Genotypes were determined using polymerase chain reaction and restriction fragment length polymorphism technique. Allelic and genotypic frequencies were compared between both study groups. NADPH p22phox -A930G polymorphism was significantly associated with knee OA in the crude analysis (P = 0.018). No significant difference was detected for C242T and A640G polymorphisms (P > 0.05). The association between -A930G polymorphism and knee OA disappeared when the results were adjusted for obesity (P = 0.078, odds ratio 0.54, 95 % CI 0.272-1.071). The interaction between all three polymorphisms was not significant. The present study shows that NADPH oxidase p22phox gene C242T, A640G and -A930G polymorphisms are not risk factors for knee OA susceptibility in the Greek population. Further studies are needed to give a global view of the importance of this polymorphism in the pathogenesis of OA.

CYBA C242T polymorphism is associated with obesity and diabetes mellitus in Brazilian hypertensive patients

AIMS

The CYBA C242T polymorphism has been associated with cardiovascular phenotypes such as hypertension and atherosclerosis, but available data are conflicting. This report investigated the impact of this variant on hypertension and metabolic determinants of cardiovascular risk in a large Brazilian sample.

METHODS

We cross-sectionally evaluated 1856 subjects (826 normotensive subjects and 1030 hypertensive patients) by clinical history, anthropometry, laboratory analysis and genotyping of the CYBA C242T polymorphism.

RESULTS

Genotype frequencies in the whole population were consistent with the Hardy-Weinberg equilibrium and genotype distributions were not different between hypertensive and normotensive subjects. Hypertensive patients with the CC genotype presented lower fasting plasma glucose levels (5.9 ± 0.1 vs. 6.2 ± 0.1 mmol/l, P = 0.020) and waist circumference (94.5 ± 0.6 vs. 96.3 ± 0.6 cm, P = 0.028) than CT + TT ones. Similarly, the prevalence of diabetes mellitus and obesity was also lower in hypertensive patients carrying the CC genotype (16% vs. 21%, P = 0.041; 36% vs. 43%, P = 0.029, respectively). In addition, multiple and logistic regression analysis demonstrated that the CYBA C242T polymorphism was associated with glucose levels, waist circumference, obesity and diabetes mellitus in hypertensive patients independently of potential confounders. Conversely, in normotensive subjects, no significant difference in studied variables was detected between the genotype groups.

CONCLUSIONS

These data suggest that the T allele of the CYBA C242T polymorphism may be used as a marker for adverse metabolic features in Brazilian subjects with systemic hypertension.

CYBA and GSTP1 variants associate with oxidative stress under hypobaric hypoxia as observed in high-altitude pulmonary oedema

HAPE (high-altitude pulmonary oedema) is characterized by pulmonary hypertension, vasoconstriction and an imbalance in oxygen-sensing redox switches. Excess ROS (reactive oxygen species) contribute to endothelial damage under hypobaric hypoxia, hence the oxidative-stress-related genes CYBA (cytochrome b-245 α polypeptide) and GSTP1 (glutathione transferase Pi 1) are potential candidate genes for HAPE. In the present study, we investigated the polymorphisms -930A/G and H72Y (C/T) of CYBA and I105V (A/G) and A114V (C/T) of GSTP1, individually and in combination, in 150 HAPE-p (HAPE patients), 180 HAPE-r (HAPE-resistant lowland natives) and 180 HLs (healthy highland natives). 8-Iso-PGF2α (8-iso-prostaglandin F2α) levels were determined in plasma and were correlated with individual alleles, genotype, haplotype and gene-gene interactions. The relative expression of CYBA and GSTP1 were determined in peripheral blood leucocytes. The genotype distribution of -930A/G, H72Y (C/T) and I105V (A/G) differed significantly in HAPE-p compared with HAPE-r and HLs (P≤0.01). The haplotypes G-C of -930A/G and H72Y (C/T) in CYBA and G-C and G-T of I105V (A/G) and A114V (C/T) in GSTP1 were over-represented in HAPE-p; in contrast, haplotypes A-T of -930A/G and H72Y (C/T) in CYBA and A-C of I105V (A/G) and A114V (C/T) in GSTP1 were over-represented in HAPE-r and HLs. 8-Iso-PGF2α levels were significantly higher in HAPE-p and in HLs than in HAPE-r (P=2.2×10(-16) and 1.2×10(-14) respectively) and the expression of CYBA and GSTP1 varied differentially (P<0.05). Regression analysis showed that the risk alleles G, C, G and T of -930A/G, H72Y (C/T), I105V (A/G) and A114V (C/T) were associated with increased 8-iso-PGF2α levels (P<0.05). Interaction between the two genes revealed over-representation of most of the risk-allele-associated genotype combinations in HAPE-p and protective-allele-associated genotype combinations in HLs. In conclusion, the risk alleles of CYBA and GSTP1, their haplotypes and gene-gene interactions are associated with imbalanced oxidative stress and, thereby, with high-altitude adaptation and mal-adaptation.

CYBA Gene Polymorphisms and Adverse Outcomes in Acute Kidney Injury: A Prospective Cohort Study

BACKGROUND

NADPH oxidase is an important enzyme involved in the generation of reactive oxygen species in acute kidney injury (AKI). Its key subunit, p22(phox), is encoded by the highly polymorphic CYBA gene.

METHODS

We examined the associations of CYBA gene polymorphisms across the CYBA locus (rs8854, rs3794624, rs4673, rs4782390, and rs1049255) with dialysis requirement or in-hospital death in 256 hospitalized adults with AKI. Dominant and haplotype multivariable logistic regression analyses were performed, adjusted for sex, race, age, and severity of illness.

RESULTS

The baseline characteristics of the patients were not different among genotype groups with the exception of a lower prevalence of sepsis and shock in the CYBA rs8854 A-allele group; a higher prevalence of shock in the CYBA rs4782390 T-allele group, and a higher APACHE II score in the CYBA rs1049255 G-allele group. The CYBA rs8854 A-allele had an adjusted odds ratio (OR) of 0.41 (95% confidence interval, CI, 0.18-0.96) for the outcome of dialysis requirement or in-hospital death. The CYBA rs4673 T-allele and rs1049255 G-allele had unadjusted ORs of 1.69 (95% CI 1.03-2.79) and 1.66 (95% CI 1.01-2.73) for the composite outcome, respectively, which became non-significant after multivariable adjustment. The remaining 2 polymorphisms were not associated with the outcomes of interest. Finally, the presence of the CYBA A-A-G-G haplotype (generated from rs4782390, rs4673, rs3794624, and rs8854, all in Hardy-Weinberg equilibrium) was associated with an elevated OR of 1.81 (95% CI 1.07-3.08) for dialysis requirement or in-hospital death, which was attenuated after multivariable adjustment (OR 1.80; 95% CI 0.99-3.29).

CONCLUSION

This study identifies several polymorphisms spanning the entire CYBA gene locus and a common haplotype as risk markers for dialysis requirement or in-hospital death in patients with AKI. Additional studies are needed to validate these findings.

NADPH oxidase p22phox polymorphisms and oxidative stress in patients with obstructive sleep apnoea

BACKGROUND

Obstructive Sleep Apnoea (OSA) is associated with increased oxidative stress. NADPH oxidases are the main source of Reactive Oxygen Species (ROS) in the vasculature. Several polymorphisms related to NADPH oxidase expression or activity have been identified. We compared the distribution of the allelic frequencies of A-930G and C242T polymorphisms and their possible relationship with the levels of 8-isoprostanes as a marker of oxidative stress in patients with OSA and in a control group without OSA.

METHODS

This is a case-control study. We determined the A-930G and C242T p22phox genotypes in 427 patients with OSA and in 139 healthy subjects recruited from the Sleep Unit of Son Dureta University Hospital, (Palma de Mallorca, Spain). 8-Isoprostane was measured as an oxidative stress marker.

RESULTS

The distribution of the p22phox genotypes in OSA and in control subjects was different. The risk of OSA was associated with the presence of the G allele in the A-930G p22phox independently of age, gender, Body Mass Index (BMI), hypertension, dyslipemia and diabetes, but no association was found with the C242T polymorphism. The median level of 8-isoprostane was significantly higher in OSA patients. Synergic effect in 8-Isoprostane levels was observed when these two polymorphisms were analysed together.

CONCLUSION

the A-930G polymorphism of the p22phox gene may play an important role in genetic susceptibility to OSA. Furthermore, the C242T and A-930G polymorphisms of the p22phox gene have a synergic effect on the 8-isoprostane levels, suggesting that they may be involved in the development of oxidative stress in these patients.

Update in chronic obstructive pulmonary disease: role of antioxidant and metabolizing gene polymorphisms

Chronic obstructive pulmonary disease (COPD) is characterized by systemic and local chronic inflammation and oxidative stress. The sources of the increased oxidative stress in COPD patients derive from the increased burden of inhaled oxidants such as cigarette smoke and other forms of particulate or gaseous air pollution and from the increase in reactive oxygen species (ROS) generated by several inflammatory, immune, and structural airways cells. There is increasing evidence that genetic factors may also contribute to the pathogenesis if COPD, particularly antioxidant genes, which may confer a susceptibility to environmental insults such as cigarette smoke and thereafter development of COPD. Consequently, heme oxygenase-1 (HO-1), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), microsomal epoxide hydrolase (EPHX1), and cytochrome P450 (CYP) genetic polymorphisms may have an important role in COPD pathogenesis. In this review the authors summarized the most recent findings dealing with these antioxidant genes contributing to the free radical neutralization and xenobiotic enzymes playing a role in different phases of cell detoxification reactions related to the redox status imbalance in COPD, with an emphasis on their possible roles in disease progression.

Angiotensin II and the vascular phenotype in hypertension

Hypertension is associated with vascular changes characterised by remodelling, endothelial dysfunction and hyperreactivity. Cellular processes underlying these perturbations include altered vascular smooth muscle cell growth and apoptosis, fibrosis, hypercontractility and calcification. Inflammation, associated with macrophage infiltration and increased expression of redox-sensitive pro-inflammatory genes, also contributes to vascular remodelling. Many of these features occur with ageing, and the vascular phenotype in hypertension is considered a phenomenon of ‘premature vascular ageing’. Among the many factors involved in the hypertensive vascular phenotype, angiotensin II (Ang II) is especially important. Ang II, previously thought to be the sole effector of the renin–angiotensin system (RAS), is converted to smaller peptides [Ang III, Ang IV, Ang-(1-7)] that are biologically active in the vascular system. Another new component of the RAS is the (pro)renin receptor, which signals through Ang-II-independent mechanisms and might influence vascular function. Ang II mediates effects through complex signalling pathways on binding to its G-protein-coupled receptors (GPCRs) AT1R and AT2R. These receptors are regulated by the GPCR-interacting proteins ATRAP, ARAP1 and ATIP. AT1R activation induces effects through the phospholipase C pathway, mitogen-activated protein kinases, tyrosine kinases/phosphatases, RhoA/Rhokinase and NAD(P)H-oxidase-derived reactive oxygen species. Here we focus on recent developments and new research trends related to Ang II and the RAS and involvement in the hypertensive vascular phenotype.

Vascular BDNF expression and oxidative stress during aging and the development of chronic hypertension

Brain-derived neurotrophic factor (BDNF) and TrK receptors play an important role in vascular development and response to injury. In this study, we investigated the participation of the BDNF/TrK pathway and oxidative stress during the development of hypertension in spontaneously hypertensive rats (SHR). In SHR and normotensive rats (WKY) at 6 and 13 weeks of age, we studied (i) plasma antioxidant capacity, (ii) production of superoxide and NAD(P)H oxidase activity in aorta (iii) plasma BDNF and vascular expression of BDNF, TrKB, NAD(P)H oxidase subunits, AT1 receptor, and MCP-1. In 6- and 13-week-old SHR aorta, superoxide level was twice than in WKY aorta. At 13 weeks, when blood pressure in SHR was 60 mmHg higher in SHR than in WKY, an enhancement of NAD(P)H oxidase activity in SHR was associated with an increase in p47phox, AT1, and BDNF expression in vessels. MCP-1 expression increased with blood pressure. Our study demonstrated that in SHR rats, an increase in levels of vascular oxidative stress and in aortic BDNF and TrKB expression occurs prior to the rise in blood pressure, while a reinforcement of vascular and circulating oxidative stress markers is brought about later by hypertension.

The effect of p22(phox) -930A/G, A640G and C242T polymorphisms of NADPH oxidase on peripheral and central pressures in healthy, normotensive individuals

The nicotinamide adenine dinucleotide phosphate (NADPH) oxidase produces superoxide, thus regulating redox state in the vessel wall. Three single-nucleotide polymorphisms (SNPs; -930A/G, A640G and C242T) of the p22(phox) subunit have been associated with hypertension; however, their role in peripheral and central pressures in normotensive individuals has not been addressed. A total of 210 healthy, normotensive individuals were studied. Genotypes for the -930A/G, A640G and C242T polymorphisms were determined by polymerase chain reaction. Peripheral pressures were measured by mercury sphygmomanometer and aortic pressures by a validated device using applanation tonometry. Both peripheral and central pressures differed across -930A/G genotypes. G allele carriers showed higher levels of peripheral systolic blood pressure (PSBP; AA: 113+/-12, GG/AG: 119+/-12 mm Hg; P<0.01) and peripheral diastolic blood pressure (AA: 70+/-9, GG/AG: 73+/-10 mm Hg; P<0.05). Regarding central pressures, AA homozygotes had lower central systolic blood pressure (CSBP; AA: 103+/-12, GG/AG: 108+/-12 mm Hg; P<0.01) and central diastolic blood pressure (AA: 71+/-9, GG/AG: 74+/-10 mm Hg; P<0.05). In multiple linear regression analysis, presence of the G allele (AG or GG) independently predicted CSBP. Blood pressure levels did not differ across A640G and C242T genotypes. The -930A/G polymorphism of p22(phox) is a determinant of peripheral and central pressures in normotensive individuals. The G allele is associated with higher blood pressure in the brachial artery, as well as in the aorta. These findings further elucidate the role of this polymorphism in the regulation of blood pressure. In contrast, the A640G and C242T SNPs do not influence peripheral and central pressures in normotensives.

Natural antioxidants and hypertension: promise and challenges

Hypertension reigns as a leading cause of cardiovascular morbidity and mortality worldwide. Excessive reactive oxygen species (ROS) have emerged as a central common pathway by which disparate influences may induce and exacerbate hypertension. Potential sources of excessive ROS in hypertension include nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, mitochondria, xanthine oxidase, endothelium-derived NO synthase, cyclooxygenase 1 and 2, cytochrome P450 epoxygenase, and transition metals. While a significant body of epidemiological and clinical data suggests that antioxidant-rich diets reduce blood pressure and cardiovascular risk, randomized trials and population studies using natural antioxidants have yielded disappointing results. The reasons behind this lack of efficacy are not completely clear, but likely include a combination of (1) ineffective dosing regimens, (2) the potential pro-oxidant capacity of some of these agents, (3) selection of subjects less likely to benefit from antioxidant therapy (too healthy or too sick), and (4) inefficiency of nonspecific quenching of prevalent ROS versus prevention of excessive ROS production. Commonly used antioxidants include Vitamins A, C and E, L-arginine, flavanoids, and mitochondria-targeted agents (Coenzyme Q10, acetyl-L-carnitine, and alpha-lipoic acid). Various reasons, including incomplete knowledge of the mechanisms of action of these agents, lack of target specificity, and potential interindividual differences in therapeutic efficacy preclude us from recommending any specific natural antioxidant for antihypertensive therapy at this time. This review focuses on recent literature evaluating naturally occurring antioxidants with respect to their impact on hypertension.

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.

Essential hypertension: is there a role for inflammatory mechanisms?

Inflammation is a key feature in the initiation, progression, and clinical implications of cardiovascular disorders, including essential hypertension. Increasing evidence shows that activation of renin-angiotensin-aldosterone system and enhanced local production of angiotensin II have been implicated in the pathophysiology of inflammation. Besides being a potent vasoactive peptide, angiotensin II regulates the inflammatory process. Specifically, it increases vascular permeability, participates in the recruitment of inflammatory cells and their adhesion to the activated endothelium, and regulates cell growth and fibrosis. Reactive oxygen species are implicated at every stage in inflammation and activate multiple intracellular signaling molecules and transcription factors associated with inflammatory responses, such as nuclear factor-kappa B and activator protein-1. Other components of the renin-angiotensin-aldosterone system, including aldosterone and/or mineralocorticoid receptor, induce the production of reactive oxygen species and participate in vascular inflammation. Several studies suggest a role of endothelin-1 as an important mediator of chronic inflammation and there is an increasing interest in the relationship between endothelin-1 and reactive oxygen species. These data may have great impact on future therapeutic strategies.

Future perspectives for the treatment of pulmonary arterial hypertension

Over the past 2 decades, pulmonary arterial hypertension has evolved from a uniformly fatal condition to a chronic, manageable disease in many cases, the result of unparalleled development of new therapies and advances in early diagnosis. However, none of the currently available therapies is curative, so the search for new treatment strategies continues. With a deeper understanding of the genetics and the molecular mechanisms of pulmonary vascular disorders, we are now at the threshold of entering a new therapeutic era. Our working group addressed what can be expected in the near future. The topics span the understanding of genetic variations, novel antiproliferative treatments, the role of stem cells, the right ventricle as a therapeutic target, and strategies and challenges for the translation of novel experimental findings into clinical practice.

The association between cigarette smoking and carotid intima-media thickness is influenced by the -930A/G CYBA gene polymorphism: the Cardiovascular Risk in Young Finns Study

BACKGROUND

Smoking-induced damage to the cardiovascular system has been shown in many studies; however, the degree of damage varies from individual to individual. We hypothesized that the -930A/G CYBA gene polymorphism in the NADPH oxidase influences the association between cigarette smoking and carotid intima-media thickness (IMT) in young healthy adults.

METHODS

Cross-sectional data obtained in 2001 for the Cardiovascular Risk in Young Finns Study were used. IMT was measured with ultrasound. The genotyping was performed using a 5'-nuclease assay. A linear regression model was used to test whether the interaction between smoking and the genotypes was associated with IMT. The magnitude of the interaction effect was further examined by performing a stratified analysis according to smoking habits.

RESULTS

In the entire population, the mean and maxima IMT were higher in smokers than nonsmokers (P = 0.005 and 0.008, respectively). The differences were most significant in subjects with the GG genotype, borderline significant for the GA genotype, and nonsignificant for the AA genotype. The interaction of genotypes with smoking was associated with mean and maximal IMT (P = 0.042 and 0.022). Among smokers, subjects with the GG genotype had a higher mean and maximal IMT compared with carriers of the A allele (P = 0.021 and 0.012). In contrast, the mean and maximal IMT were lower for G allele carriers than subjects with the AA genotype among nonsmokers (P = 0.022 and 0.026). All results had been adjusted for potential risk factors related to IMT.

CONCLUSION

The -930A/G polymorphism modifies the association between cigarette smoking and IMT in young healthy adults.

G allele of the -930A>G polymorphism of the CYBA gene is associated with insulin resistance in obese subjects

It has been shown that NADPH oxidase plays a role in oxidative stress which has been involved in the development of metabolic syndrome. The -930A/G polymorphism of the CYBA gene (that codes p22phox, a major component of the NADPH oxidase) has been associated with human hypertension and with a reduction in NADPH oxidase activity. In this work, we have examined the influence of the -930A/G polymorphism on obesity risk and insulin resistance in a case-control study of Spanish subjects (n=313). In the obese group (n=159), there was a statistically significant association between the GG genotype of the -930A/G polymorphism of the CYBA gene and fasting insulin levels and HOMA index. This outcome agrees with previous findings concerning functional analyses of this polymorphism and reinforces the hypothesis that insulin resistance is associated with oxidative stress. In conclusion, a protective effect in carriers of the -930A/G polymorphism of the p22phox gene against insulin resistance in a population of Spanish obese adults has been found.

The molecular sources of reactive oxygen species in hypertension

In both animal models and humans, increased blood pressure has been associated with oxidative stress in the vasculature, i.e. an excessive endothelial production of reactive oxygen species (ROS), which may be both a cause and an effect of hypertension. In addition to NADPH oxidase, the best characterized source of ROS, several other enzymes may contribute to ROS generation, including nitric oxide synthase, lipoxygenases, cyclo-oxygenases, xanthine oxidase and cytochrome P450 enzymes. It has been suggested that also mitochondria could be considered a major source of ROS: in situations of metabolic perturbation, increased mitochondrial ROS generation might trigger endothelial dysfunction, possibly contributing to the development of hypertension. However, the use of antioxidants in the clinical setting induced only limited effects on human hypertension or cardiovascular endpoints. More clinical studies are needed to fully elucidate this so called "oxidative paradox" of hypertension.

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.

Trophoblasts reduce the vascular smooth muscle cell proatherogenic response

Maternal spiral artery remodeling is the consequence of controlled trophoblast invasive interaction with the maternal cellular environment and is fundamentally important for successful placentation. In preeclampsia, trophoblast invasion is shallow, remodeling is incomplete, and vessels develop an inflammatory appearance, termed "acute atherosis." We noted that, in our preeclampsia, human renin-human angiotensinogen transgenic rat model, complement component 3 (C3), and tumor necrosis factor-alpha were upregulated and heavily expressed in atherotic uteroplacental vessels. We next used coculture involving human trophoblasts, rat vascular smooth muscle cells (VSMCs), and human VSMCs to observe VSMC-trophoblast regulatory interactions. Tumor necrosis factor-alpha induced complement C3 and interleukin-6 expression in VSMCs. We found that trophoblasts were able to reduce VSMC C3 and interleukin-6 expression after the VSMCs were stimulated with tumor necrosis factor-alpha. However, a direct VSMC-trophoblast cell-cell contact was necessary for this anti-inflammatory response. We also studied double-transgenic VSMCs that express inflammatory components and exhibit accelerated proliferation ("synthetic" phenotype). Trophoblasts could not downregulate C3 in these cells. We then examined uteroplacental tissues from preeclamptic and control patients. In control deciduas, only traces of C3 staining were observed, and vessels were thin walled without thrombus formation. In preeclampsia, the decidual vessels showed atherosis, thrombus formation, and C3 expression. Our data suggest that fetally derived trophoblasts require direct cell-cell contact with maternally derived VSMCs to downregulate VSMC C3 and interleukin-6 expression and to avoid atherosis. The findings also implicate C3 in the placental vasculopathy observed in preeclampsia.

Regulation of NADPH oxidase subunit p22(phox) by NF-kB in human aortic smooth muscle cells

Accumulating evidence demonstrates the involvement of oxidative stress in the pathophysiology of cardiovascular diseases. The molecular mechanisms accountable for the increased production of reactive oxygen species remain uncertain. Among others, NADPH oxidase is one of the most important sources of superoxide in vascular cells. Here we investigate the role of NF-kB in the regulation of p22(phox) subunit and NADPH oxidase activity, in human aortic smooth muscle cells. Overexpression of p65/RelA or IKKbeta up-regulated p22(phox) gene promoter activity. Transcription factor pull-down assays demonstrated the physical interaction of p65/RelA protein with predicted NF-kB binding sites. Real time PCR and Western blotting analysis showed that p22(phox) mRNA and protein expression are significantly down-regulated by NF-kB decoy oligodeoxynucleotides and N-alpha-tosyl-l-phenylalanine chloromethyl ketone (TPCK). Lucigenin-enhanced chemiluminescence assay revealed that NF-kB inhibitors reduce the NADPH-dependent superoxide production. Regulation of NADPH oxidase by NF-kB may represent a possible mechanism whereby pro-inflammatory factors induce oxidative stress in atherosclerosis, hypertension, diabetes, stroke or heart failure.

A novel CYBA variant, the -675A/T polymorphism, is associated with essential hypertension

OBJECTIVE

Oxidative stress is implicated in hypertension and the NADPH oxidase systems constitute the main source of superoxide in vascular wall. We searched for new polymorphisms within the CYBA promoter, the human gene that encodes the p22phox protein, and studied their potential association with essential hypertension.

DESIGN

A case-control study in a random sample of the general population.

METHODS

CYBA polymorphisms were determined by restriction fragment length polymorphism and allelic discrimination. NADPH oxidase activity was quantified in phagocytic cells by chemiluminescence.

RESULTS

We identified three novel polymorphisms, at positions -852, -675 and -536 from the ATG codon. Only the -675(A/T) polymorphism associated with essential hypertension. The prevalence of the TT genotype and the T allele frequency were significantly higher (P < 0.05) in hypertensives than in normotensives. Furthermore, TT hypertensives exhibited higher (P < 0.05) systolic blood pressure values than TA/AA hypertensives. Increased phagocytic NADPH oxidase activity was observed in TT subjects compared to TA and AA individuals (P < 0.05). Enhanced carotid intima-media thickness, a surrogate marker of atherosclerosis, was found in TT subjects compared to TA and AA individuals (P < 0.05). Finally, mutagenesis experiments demonstrated a functional role of this polymorphism on the CYBA promoter activity.

CONCLUSION

The -675 (A/T) CYBA polymorphism may be a novel genetic marker associated with essential hypertension. Furthermore, TT subjects exhibit features of NADPH oxidase-mediated oxidative stress and asymptomatic atherosclerosis.

Genetic polymorphisms of NAD(P)H oxidase: variation in subunit expression and enzyme activity

Genetic polymorphisms in superoxide-producing NAD(P)H oxidase have been linked to cardiovascular diseases including anthracycline-induced cardiotoxicity. We quantified NAD(P)H oxidase activity in granulocytes of 81 healthy Caucasian volunteers (in addition, 51 in an independent confirmatory study) by chemiluminescence using the luminol analogue L-012. Expression of CYBA, NCF4 and RAC2 coding for NAD(P)H oxidase subunits was measured in whole blood cells in 59 study participants by real-time PCR. Of the five variants investigated (-930A>G, 242C>T, 640A>G in CYBA and the recently reported -368G>A in NCF4 and 7508T>A in RAC2), only CYBA 640A>G was consistently associated with superoxide production (640GG carriers 28% less than AA individuals, P=0.05 in each cohort, P=0.005 in combined analysis). RAC2 7508T>A was related to higher expression of RAC2 (P=0.02) and NCF4 (P=0.04). In summary, CYBA 640A>G rather than 242C>T was associated with reduced activity. The quantitatively moderate effect and the high intra-individual variability should be considered for further study design.

Difference in Neutrophil Superoxide Generation During Pregnancy Between Preeclampsia and Essential Hypertension

This study investigated whether production of reactive oxygen species by neutrophils differs between women with preeclampsia and those with essential hypertension. First, we assessed superoxide production by neutrophils during pregnancy and 4 weeks after delivery in 15 healthy pregnant women, 12 women with preeclampsia, and 7 pregnant women with essential hypertension. We then examined effects of serum from each subject on superoxide production by neutrophils obtained from healthy nonpregnant women. Neutrophil superoxide production was measured by cytochrome C reduction. N-formyl-methionyl-leucyl-phenylalanine-stimulated superoxide production was significantly increased in neutrophils from women with preeclampsia and women with essential hypertension compared with normal pregnant women. Four weeks postpartum, the level of superoxide production was significantly decreased in women with preeclampsia but not in women with either normal pregnancy or essential hypertension. When neutrophils obtained from nonpregnant women were preincubated with predelivery sera from each group, sera from women with preeclampsia significantly enhanced superoxide production compared with sera from the other 2 groups. When postpartum serum was used, enhancement of neutrophil superoxide production by serum from women with preeclampsia was significantly decreased compared with that by predelivery serum. In conclusion, increased neutrophil superoxide production resolved after delivery in preeclampsia, whereas activation persisted postpartum in women with essential hypertension. The different transition of neutrophil superoxide production in response to pregnancy appears to be that preeclampsia is characterized by the presence of serum factors that enhance neutrophil superoxide production. Thus, in preeclampsia, serum factors bear a more essential role producing superoxide than a behavior of neutrophils.

Associations of polymorphism of P22(phox) C242T, plasma levels of vitamin E, and smoking with coronary heart disease in China

BACKGROUND

The C242T polymorphisms of P22(phox) and plasma vitamin E have been associated with the risk of coronary heart disease (CHD) in several studies, but the results have been inconsistent. In this study, we sought to examine potential interactions between P22(phox) genotypes, plasma vitamin E concentrations, and smoking in relation to CHD risk.

METHODS

We determined C242T genotype frequency in the P22(phox) gene and plasma levels of vitamin E in 565 Chinese patients with CHD and 609 control subjects. Logistic regression was used to control for potential confounders in multivariate analyses.

RESULTS

Compared with subjects with a CC genotype, subjects with a CT or TT genotype had a lower risk of CHD (multivariate-adjusted odds ratio [OR] 0.45, 95% CI 0.28-0.74, P = .001). Plasma concentrations of vitamin E were lower in case patients than in control subjects (multivariate-adjusted OR 0.65, 95% CI 0.50-0.86, P = .025). Compared with nonsmokers with a CC genotype, nonsmokers with a CT or TT genotype had a decreased risk of CHD (OR 0.25, 95% CI 0.12-0.53), but smokers with a CT or TT genotype had an increased risk (OR 2.04, 95% CI 0.74-5.61, P for interaction = .039). Smokers with a lower vitamin E concentration had a >3.0-fold greater risk of CHD than did nonsmokers with a higher vitamin E concentration (OR 3.52, 95% CI 2.36-5.24, P for interaction = .041).

CONCLUSIONS

These data provide evidence that P22(phox) genotypes are significantly associated with CHD risk in a Chinese population and suggest potential interactions among smoking, P22(phox) genotypes, and vitamin E in relation to CHD risk.

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.

Non-effect of p22-phox −930A/G polymorphism on end-organ damage in Brazilian hypertensive patients

The p22-phox subunit is an essential component of NAD(P)H oxidase enzymatic complex, which is considered the major source of oxidative stress products in the cardiovascular system. The -930G allele of p22-phox has been associated with higher promoter activity, increased NAD(P)H oxidase-mediated oxidative stress and hypertension. We recently reported that left ventricular hypertrophy is accompanied by increased myocardial p22-phox expression in aortic-banded rats, suggesting that this protein might be involved in hypertensive cardiac hypertrophy.

The effect of estrogens on superoxide anion generation by human neutrophil granulocytes: possible consequences of the antioxidant defense

The present study aimed to test whether, beyond the known antioxidant effect of estradiol, such a property is also possessed by estrone and estriol. For this purpose, an in vitro investigation of the effect of estrone and estriol on superoxide anion production by human neutrophil granulocytes was carried out. Blood samples were obtained from healthy volunteers and neutrophil granulocytes were separated for measurement of superoxide anion generation after incubation with estrone, estriol (10(-7), 10(-6) and 10(-5) M) and 17beta-estradiol (10(-7) M). Superoxide anion production of isolated neutrophil granulocytes was quantified by photometry and using the reduction of ferricytochrome-C. When adding estrone and estriol to neutrophil granulocyte suspensions, the production of superoxide anion fell (10(-5) M: 84.17 +/- 3.14% and 88.77 +/- 1.98% of control production, p < 0.01 and p < 0.05, respectively). Estradiol produced an antioxidant effect at lower concentration (10(-7) M: 72.91 +/- 7.94% of control production, p < 0.001). The weak estrogens estrone and estriol, similarly to estradiol, are also able to reduce the superoxide anion release in our experimental model. This may have importance in the antioxidant defense of biological systems.