Assessment of Oxidative Stress Markers and Carotid Artery Intima-Media Thickness in Elderly Patients Without and with Coronary Artery Disease.

We aimed to assess whether measuring carotid intima-media thickness (CIMT) and oxidative stress markers such as protein carbonyls, malondialdehyde, nitrate and glutathione in plasma of elderly patients without and with coronary artery disease (CAD) identifies early risk for CAD. A total of 50 cases with cardiovascular risk factors over the age of 60 years without CAD, and 50 patients with angiographically documented CAD over the age of 60 years were included in the study. Control group consists of 200 healthy individuals without the risk factors. Demographic details were obtained from all the subjects and CIMT measured by high frequency ultrasound and oxidative stress markers such protein carbonyls, malondialdehyde and total glutathione were determined in plasma by spectrophotometric methods. The distribution of cardiovascular risk factors in without CAD and CAD cases were smokers (16 vs 56 %), hypertension (26 vs 64 %), diabetes (16 vs 56 %) and dyslipidemia (18 vs 58 %) and positive family history (4 vs 38 %). None of the control group had any cardiovascular risk factors. Among the CAD cases, 16 % had single vessel disease, 44 % had double vessel disease and 40 % had triple vessel disease. The CIMT was significantly increased in CAD cases as compared to cases without CAD and healthy controls. On the other hand, CIMT was significantly increased in cases without CAD as compared to healthy controls. CIMT also increased with the duration of diabetes in patients without CAD and severity of disease in CAD cases. The levels of oxidants like plasma malondialdehyde, protein carbonyls, were significantly elevated and antioxidant glutathione levels and nitrate levels were significantly reduced in cases with and without CAD as compared to healthy controls. Oxidative stress markers and CIMT was found to be significantly increased in patients with cardiovascular risk factors like diabetes, family history of CAD, dyslipidemia, hypertension and smoking when compared to patients without risk factors. In patients with diabetes, CIMT increased as duration of disease increases and also in poorly controlled diabetes. In CAD group, when number of vessel involvement (severity of coronary disease) increases, the CIMT also increases confirming that CIMT is a quantifiable risk factor for CAD.

Oxidative stress in coronary artery disease: epigenetic perspective.

The association between oxidative stress and coronary artery disease (CAD) is well documented. However, the role of epigenetic factors contributing to oxidative stress is relatively unexplored. In this study, we aimed to explore the impact of DNA methylation profile in BCL2/E1B adenovirus interacting protein 3 (BNIP3), extracellular superoxide dismutase (EC-SOD) and glutathione-S-transferase P1 (GSTP1) on the oxidative stress in CAD. Further, the contribution of folate pathway genetic polymorphisms in regulating epigenome was elucidated. The expression of BNIP3, EC-SOD, and GSTP1 were studied by using Maxima@SYBR-green based real-time qPCR approach in peripheral blood samples. Combined bisulfite restriction analysis and methylation-specific PCR were used to study promoter CpG island methylation. Further, the effect of homocysteine on BNIP3 gene expression was studied in human aortic endothelial cells in vitro. CAD cases exhibited upregulation of BNIP3, downregulation of EC-SOD and GSTP1. Hypomethylation of BNIP3 and hypermethylation of EC-SOD were observed in CAD cases. The expression of BNIP3 was positively correlated with homocysteine, MDA, protein carbonyls, and methylene tetrahydrofolate reductase C677T, while showing inverse association with cytosolic serine hydroxymethyl transferase C1420T. The expressions of EC-SOD and GSTP1 showed positive association with thymidylate synthase (TYMS) 2R3R, while inverse association with MDA, protein carbonyls, and methionine synthase reductase (MTRR) A66G. In vitro analysis showed homocysteine-dependent upregulation of BNIP3. The results of this study suggest that the aberrations in one-carbon metabolism appear to induce altered gene expression of EC-SOD, GSTP1, and BNIP3, and thus contribute to the increased oxidative stress and increased susceptibility to CAD.

Role of CYP1A1 haplotypes in modulating susceptibility to coronary artery disease.

To investigate the role of cytochrome P450 1A1 (CYP1A1) haplotypes in modulating susceptibility to coronary artery disease (CAD), a case-control study was conducted by enrolling 352 CAD cases and 282 healthy controls. PCR-RFLP, multiplex PCR, competitive ELISA techniques were employed for the analysis of CYP1A1 [ml (T-->C), m2 (A-->G) and m4 (C-->A)] haplotypes, glutathione-S-transferase (GST)T1/GSTM1 null variants and plasma 8-oxo-2'deoxyguanosine (8-oxodG) respectively. Two CYP1A1 haplotypes, i.e. CAC and TGC showed independent association with CAD risk, while all-wild CYP1A1 haplotype i.e. TAC showed reduced risk for CAD. All the three variants showed mild linkage disequilibrium (D': 0.05 to 0.17). GSTT1 null variant also exerted independent association with CAD risk (OR: 2.53, 95% CI 1.55-4.12). Among the conventional risk factors, smoking showed synergetic interaction with CAC haplotype of CYP1A1 and GSTT1 null genotype in inflating CAD risk. High risk alleles of this pathway showed dose-dependent association with percentage of stenosis and number of vessels affected. Elevated 8-oxodG levels were observed in subjects with CYP1A1 CAC haplotype and GSTT1 null variant. Multiple linear regression model of these xenobiotic variants explained 36% variability in 8-oxodG levels. This study demonstrated the association of CYP1A1 haplotypes and GSTT1 null variant with CAD risk and this association was attributed to increased oxidative DNA damage.