Influence of cytochrome P450 2C9*2 and 2C9*3 variants on the risk of ischemic stroke: a cross-sectional case-control study

CYP metabolic pathway related gene polymorphism increases the risk of embolic and atherothrombotic stroke and vulnerable carotid plaque in southeast China

OBJECTIVE

To investigate the association of CYP metabolic pathway-related genetic polymorphisms with the susceptibility to ischemic stroke and stability of carotid plaque in southeast China.

METHODS

We consecutively enrolled 294 acute ischemic stroke patients with carotid plaque and 282 controls from Wenling First People's Hospital. The patients were divided into the carotid vulnerable plaque group and stable plaque group according to the results of carotid B-mode ultrasonography. Polymorphisms of CYP3A5 (G6986A, rs776746), CYP2C9*2 (C430T, rs1799853), CYP2C9*3 (A1075C, rs1057910), and EPHX2 (G860A, rs751141) were determined using polymerase chain reaction and mass spectrometry analysis.

RESULTS

EPHX2 GG may reduce the susceptibility to ischemic stroke (OR = 0.520, 95% CI: 0.288 ∼ 0.940, P = 0.030) and AA+AG may increase the risk for ischemic stroke (OR = 1.748, 95% CI: 1.001 ∼ 3.052, P = 0.050). The distribution of CYP3A5 genotypes showed significant differences between the vulnerable plaque and stable plaque groups (P = 0.026). Multivariate logistic regression analysis found that CYP3A5 GG could reduce the risk of vulnerable plaques (OR = 0.405, 95% CI: 0.178 ∼ 0.920, P = 0.031).

CONCLUSION

EPHX2 G860A polymorphism may reduce the stroke susceptibility, while other SNPs of CYP genes are not associated with ischemic stroke in southeast China. Furthermore CYP3A5 polymorphism was related with carotid plaque instability.

Association of CYP1A1 Gene Polymorphism with Ischemic Stroke in South Indian Population

Stroke is a major cause of morbidity and mortality worldwide. Genetic and environmental factors are involved in the pathogenesis of stroke. Hypertension, diabetes mellitus, and cigarette smoking are the major risk factors, and smoking doubles the risk of ischemic stroke. Smoking cessation decreased the risk for ischemic stroke. CYP1A1 is the phase I metabolizing enzyme which plays a key role in metabolic activation of polycyclic aromatic hydrocarbons which are present in cigarette smoke and considered carcinogenic. So far, the association of CYP1A1 gene polymorphism with stroke has not been investigated in Indian population. So, the study is taken up to evaluate the association of this polymorphism with ischemic stroke in a South Indian population. We genotyped 215 ischemic stroke patients and 162 age-matched controls using polymerase chain reaction-restriction fragment length polymorphism. Statistical analysis showed that CYP1A1 "CC" genotype is associated with five times increased risk of ischemic stroke (odds ratio (OR) = 5.14; 95% confidence interval (95% CI) = 1.14-23.14, p = 0.01), while "TT" (OR = 0.78, 95% CI = 0.51-1.19, p = 0.25) and "TC" (OR = 1.04, 95% CI = 0.67-1.60, p = 0.85) genotypes were nonsignificant with the increased risk of stroke. T and C allele frequencies in stroke were 76.5% and 23.5% as against 81.8% and 18.2% in control group, respectively, thus, suggesting no statistically significant differences in the T (OR = 0.72, 95% CI = 0.50-1.03, p = 0.07) and C (OR = 1.37, 95% CI = 0.96-1.97, p = 0.07) allele frequencies between the two groups. The distribution of CYP1A1 genotypes and allelic frequency within the stroke subtypes showed a significant association of CC genotype only in intracranial large artery atherosclerosis (OR = 5.21, 95% CI = 1.03-26.38, p = 0.02) while other subtypes did not show any association. Further analysis of CYP1A1 genotypes in patients and control subjects with smoking habit also showed a similar trend. Hence, we conclude that the CYP1A1 CC genotype is associated with the increased risk of ischemic stroke.

Epoxyeicosanoid signaling in CNS function and disease

Epoxyeicosatrienoic acids (EETs) are arachidonic acid metabolites of cytochrome P450 epoxygenase enzymes recognized as key players in vascular function and disease, primarily attributed to their potent vasodilator, anti-inflammatory and pro-angiogenic effects. Although EETs' actions in the central nervous system (CNS) appear to parallel those in peripheral tissue, accumulating evidence suggests that epoxyeicosanoid signaling plays different roles in neural tissue compared to peripheral tissue; roles that reflect distinct CNS functions, cellular makeup and intercellular relationships. This is exhibited at many levels including the expression of EETs-synthetic and -metabolic enzymes in central neurons and glial cells, EETs' role in neuro-glio-vascular coupling during cortical functional activation, the capacity for interaction between epoxyeicosanoid and neuroactive endocannabinoid signaling pathways, and the regulation of neurohormone and neuropeptide release by endogenous EETs. The ability of several CNS cell types to produce and respond to EETs suggests that epoxyeicosanoid signaling is a key integrator of cell-cell communication in the CNS, coordinating cellular responses across different cell types. Under pathophysiological conditions, such as cerebral ischemia, EETs protect neurons, astroglia and vascular endothelium, thus preserving the integrity of cellular networks unique to and essential for proper CNS function. Recognition of EETs' intimate involvement in CNS function in addition to their multi-cellular protective profile has inspired the development of therapeutic strategies against CNS diseases such as cerebral ischemia, tumors, and neural pain and inflammation that are based on targeting the cellular actions of EETs or their biosynthetic and metabolizing enzymes. Based upon the emerging importance of epoxyeicosanoids in cellular function and disease unique to neural systems, we propose that the actions of "neuroactive EETs" are best considered separately, and not in aggregate with all other peripheral EETs functions.

Role of CYP2C9 and CYP2C19 polymorphisms in patients with atherosclerosis

The arachidonic acid metabolizing CYP enzymes with prominent roles in vascular regulation are epoxygenases of the two gene family which generate epoxyeicosatrienoic acids. Carriers of CYP2C9 mutant alleles exhibit a diminished CYP2C9 metabolic capacity leading to decreased endothelium-derived hyperpolarizing factors (EDHF) synthesis and an increased risk for atherosclerosis. We investigated whether the polymorphisms of CYP2C9/19 are related with atherosclerosis. We examined 108 patients having angioraphically > or =70 coronary artery narrowing and 90 healthy controls. CYPC2C9/19*2 and CYP2C9/19*3 alleles were investigated in both patients and controls by a real time PCR instrument. There was no significant difference in the distribution of the CYP2C9*2/*3 alleles between cases and the controls. We found that smoker patients having CYP2C9*2 heterozygote genotype have 3.7-fold risk of developing atherosclerosis. CYP2C19*3 heterozygote alleles are more frequent in patients than in controls (10.2%, 5.6% respectively) and it is related with a three-fold risk of atherosclerosis (odds ratio (OR) = 3.75, confidence interval (CI) = 0.75-18.65). It becomes clear that cigarette smoking can cause almost all major diseases prevalent today, such as cancer or heart disease. This inter-subject variability in cigarette-induced pathologies is partly mediated by genetic variants of genes that may participate in detoxification processes, e.g., cytochrome P450 (CYP), cellular susceptibility to toxins, such as p53, or disease development such as atherosclerosis.

Cytochrome P450 enzymes: Central players in cardiovascular health and disease

Cardiovascular disease (CVD) is a human health crisis that remains the leading cause of death worldwide. The cytochrome P450 (CYP) class of enzymes are key metabolizers of both xenobiotics and endobiotics. Many CYP enzyme families have been identified in the heart, endothelium and smooth muscle of blood vessels. Furthermore, mounting evidence points to the role of endogenous CYP metabolites, such as epoxyeicosatrienoic acids (EETs), hydroxyeicosatetraenoic acids (HETEs), prostacyclin (PGI(2)), aldosterone, and sex hormones, in the maintenance of cardiovascular health. Emerging science and the development of genetic screening have provided us with information on the differences in CYP expression among populations and groups of individuals. With this information, a link between CYP expression and activity and CVD, such as hypertension, coronary artery disease (CAD), myocardial infarction, heart failure, stroke, and cardiomyopathy and arrhythmias, has been established. In fact many currently used therapeutic modalities in CVD owe their therapeutic efficacy to their effect on CYP metabolites. Thus, the evidence for the involvement of CYP in CVD is numerous. Concentrating on treatment modalities that target the CYP pathway makes ethical sense for the affected individuals and decreases the socioeconomic burden of this disease. However, more research is needed to allow the integration of this information into a clinical setting.