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

The Protective Effects of the Combination of Vitamin E and Swimming Exercise on Memory Impairment Induced by Exposure to Waterpipe Smoke

BACKGROUND

Waterpipe smoking (WP) exposure involves a negative health impact, including memory deficit, which is attributed to the elevation of oxidative stress. Vitamin E (VitE) in combination with swimming exercise exerts protective effects that prevent memory impairment. In the current study, the modulation of WP-induced memory impairment by the combined effect of VitE and swimming exercise (SE) was investigated.

METHODS

Animals were exposed to WP one hour/day, five days per week for four weeks. Simultaneously, VitE (100 mg/kg, six days/week for four weeks) was administered via oral gavage, and the rats were made to swim one hour/day, five days/week for four weeks. Changes in memory were evaluated using radial arm water maze (RAWM), and oxidative stress biomarkers were examined in the hippocampus.

RESULTS

WP exposure induced short-term/long-term memory impairment (p<0.05). This impairment was prevented by a combination of VitE with SE (p<0.05). Additionally, this combination normalized the hippocampal catalase, GPx, and GSH/GSSG ratios that were modulated by WP (p<0.05). The combination further reduced TBARs levels below those of the control group (p<0.05).

CONCLUSION

WP-induced memory impairments were prevented by the combination of VitE with SE. This could be attributed to preserving the hippocampal oxidative mechanism by combining VitE and SE during WP exposure.

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

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

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

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

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

Background

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

Methods

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

Results

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

Conclusions

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

NADPH oxidase and the cardiovascular toxicity associated with smoking

Smoking is one of the most serious but preventable causes of cardiovascular disease (CVD). Key aspects of pathological process associated with smoking include endothelial dysfunction, a prothrombotic state, inflammation, altered lipid metabolism, and hypoxia. Multiple molecular events are involved in smokinginduced CVD. However, the dysregulations of reactive oxygen species (ROS) generation and metabolism mainly contribute to the development of diverse CVDs, and NADPH oxidase (NOX) has been established as a source of ROS responsible for the pathogenesis of CVD. NOX activation and resultant ROS production by cigarette smoke (CS) treatment have been widely observed in isolated blood vessels and cultured vascular cells, including endothelial and smooth muscle cells. NOX-mediated oxidative stress has also been demonstrated in animal studies. Of the various NOX isoforms, NOX2 has been reported to mediate ROS generation by CS, but other isoforms were not tested thoroughly. Of the many CS constituents, nicotine, methyl vinyl ketone, and α,β-unsaturated aldehydes, such as, acrolein and crotonaldehyde, appear to be primarily responsible for NOX-mediated cytotoxicity, but additional validation will be needed. Human epidemiological studies have reported relationships between polymorphisms in the CYBA gene encoding p22phox, a catalytic subunit of NOX and susceptibility to smoking-related CVDs. In particular, G allele carriers of A640G and -930^A/G polymorphisms were found to be vulnerable to smoking-induced cardiovascular toxicity, but results for C242T studies are conflicting. On the whole, evidence implicates the etiological role of NOX in smoking-induced CVD, but the clinical relevance of NOX activation by smoking and its contribution to CVD require further validation in human studies. A detailed understanding of the role of NOX would be helpful to assess the risk of smoking to human health, to define high-risk subgroups, and to develop strategies to prevent or treat smoking-induced CVD.

C242T polymorphism of NADPH oxidase p22phox gene reduces the risk of coronary artery disease in a random sample of Egyptian population

The p22phox protein subunit is essential for NADPH oxidase activity. The prevalence of C242T variants of p22phox gene was studied in 101 healthy Egyptian controls and 104 acute myocardial infarction (AMI) Egyptian patients. Contribution of oxidative stress, represented by serum oxidized-LDL (ox-LDL), in development of AMI was also examined and correlated with C242T gene variants. Genotyping and ox-LDL were assessed by PCR-RFLP and ELISA. Results showed that wild type CC genotype is prevalent in 27 % of controls; CT and TT are in 72 and 1 %. In patients, the distribution was 40.2, 59.8 and 0 % for CC, CT and TT; respectively, showing a significant difference (p = 0.0259). Serum ox-LDL levels were higher in patients than controls (p ≤ 0.0001). Subjects having CT genotype had lower levels of ox-LDL than CC genotype (p ≤ 0.005). C242T polymorphism of p22phox gene of NADPH oxidase is a novel genetic marker associated with reduced susceptibility to AMI.

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.

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

Background

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

Methods

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

Results

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

Conclusion

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

Association between the C242T polymorphism in the p22phox gene with arterial stiffness in the Brazilian population

NADPH oxidase p22phox subunit is responsible for the production of reactive oxygen species in the vascular tissue. The C242T polymorphism in the p22phox gene has been associated with diverse coronary artery disease phenotypes, but the findings about the protective or harmful effects of the T allele are still controversial. Our main aim was to assess the effect of p22phox C242T genotypes on arterial stiffness, a predictor of late morbidity and mortality, in individuals from the general population. We randomly selected 1,178 individuals from the general population of Vitoria City, Brazil. Genotypes for the C242T polymorphism were detected by PCR-RFLP, and pulse wave velocity (PWV) values were measured with a noninvasive automatic device Complior. p22phox and TNF-α gene expression were quantified by real-time PCR in human arterial mammary smooth muscle cells. In both the entire and nonhypertensive groups: individuals carrying the TT genotype had higher PWV values and higher risk for increased arterial stiffness [odds ratio (OR) 1.93, 95% confidence interval (CI) 1.27-2.92 and OR 1.78, 95% CI 1.07-2.95, respectively] compared with individuals carrying CC+CT genotypes, even after adjustment for covariates. No difference in the p22phox gene expression according C242T genotypes was observed. However, TNF-α gene expression was higher in cells from individual carrying the T allele, suggesting that this genetic marker is associated with functional phenotypes at the gene expression level. In conclusion, we suggest that p22phox C242T polymorphism is associated with arterial stiffness evaluated by PWV in the general population. This genetic association shed light on the understanding of the genetic modulation on vascular dysfunction mediated by NADPH oxidase.

Smoking dose modifies the association between C242T polymorphism and prevalence of metabolic syndrome in a Chinese population

BACKGROUND

The C242T polymorphism of the CYBA gene that encodes p22phox, a component of NADPH oxidase, has been found to modulate superoxide production. Oxidase is a major source of the superoxide anion that contributes to individual components of metabolic syndrome. We examined the relationship of the C242T polymorphism with the prevalence of metabolic syndrome in a Chinese population, taking account of consumed cigarette amounts.

METHODOLOGY/PRINCIPAL FINDINGS

In 870 participants, we collected biomarkers related to metabolic syndrome and detailed history of smoking and genotyped the C242T polymorphisms. After adjustment for covariates, the CT/TT genotypes were associated with a lower risk of metabolic syndrome (P = 0.0008). The odds of having metabolic syndrome in the CT/TT participants were 0.439 (95%CI: 0.265, 0.726), while for CC participants the odds were 1.110 (95%CI: 0.904, 1.362). There was significant (P = 0.014) interaction between the C242T polymorphism and smoking status in relation to the prevalence of metabolic syndrome. For smokers who smoke no less than 25 pack-years, those with CT/TT genotypes had lower risk of metabolic syndrome as compared with CC polymorphism carriers (P = 0.015). In the multiple regression analysis, the CT/TT genotypes were significantly associated with lower serum concentration of triglycerides both in all subjects and smokers; furthermore, the CT/TT genotypes were also related to smaller waist circumference in smokers.

CONCLUSIONS

Our study suggests that the C242T gene polymorphism is indeed related to the prevalence of metabolic syndrome and smoking dose might modify this association.

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.

Association of the CYBA, PPARGC1A, PPARG3, and PPARD gene variants with coronary artery disease and metabolic risk factors of coronary atherosclerosis in a Russian population

Abnormalities in lipid metabolism and enhanced oxidative stress are considered as major risk factors for coronary atherosclerosis. Functional genetic variations in genes whose products are involved in lipid metabolism and antioxidant defense could therefore modulate risk of coronary artery disease (CAD). In this study, we evaluate whether the PPARGC1A Gly482Ser, PPARG3 (-681)C/G, PPARD +294T/C, and CYBA +242C/T gene variants confer the risk of CAD in a Russian population. A total of 313 CAD patients and 132 controls with no clinical sign of CAD were studied. The polymorphic markers were tested using a TaqMan assay. Allele and genotype frequencies in CAD patients and controls were compared using the Yates chi(2) test. Association of the genetic markers with metabolic risk factors of arterial atherosclerosis was studied using the analysis of variance test and then adjusted for conventional risk factors in the multiple regression analysis. For CYBA +242C/T, both the allele T and genotype T/T showed significant association with higher risk of CAD (odds ratio =1.49 and 3.89, respectively). The allele C and genotype C/C of the +294T/C marker of PPARD were associated with increased risk of CAD providing an odds ratio of 2.12 and 2.78, respectively. The risk variants of CYBA +242C/T and PPARD +294T/C markers were associated with higher low-density lipoprotein cholesterol and increased total serum cholesterol, respectively. In conclusion, the CYBA +242C/T and PPARD +294T/C variants modulate risk of CAD through their associations with atherogenic serum lipid profiles.

Cardioprotection with alpha-tocopheryl phosphate: amelioration of myocardial ischemia reperfusion injury is linked with its ability to generate a survival signal through Akt activation

The emerging potential of alpha-tocopheryl phosphate, a phosphoric acid ester of alpha-tocopherol, in health benefits was tested gavaging this compound (5 mg/kg body wt) to a group of rats for a period of thirty days while the control rats were given water only. After thirty days, the rats were sacrificed, the hearts excised, and the isolated hearts were perfused by working mode. Both control and experimental hearts were subjected to 30-min global ischemia followed by 2 h of reperfusion. The tocopheryl phosphate fed rats exhibited significant cardioprotection as evidenced by improved ventricular performance and reduced myocardial infarct size and cardiomyocyte apoptosis. Supplementation with alpha-tocopheryl phosphate converted MAP kinase-induced death signal into a survival signal by enhancing anti-apoptotic p42/44 ERK kinase and p38 MAPKbeta and reducing pro-apoptotic proteins p38 MAPKalpha and JNK. In concert, the phosphorylation of pro-apoptotic c-Src was also reduced. Tocopheryl phosphate increased the DNA binding of the redox-sensitive transcription factor NFkappaB and potentiated the activation of anti-death protein Bcl-2 and survival signaling protein Akt. The results of this study demonstrated for the first time that tocopheryl phosphate could ameliorate myocardial ischemic reperfusion injury by converting ischemia/reperfusion-mediated death signal into a survival signal by modulating MAP kinase signaling.