Association of common variants of CYP4A11 and CYP4F2 with stroke in the Han Chinese population

Association among VKORC1 rs9923231, CYP4F2 rs2108622, GGCX rs11676382 polymorphisms and acute ischemic stroke

Acute ischemic stroke is a major cause of morbidity and mortality worldwide, and genetic factors play a role in the risk of stroke. Single nucleotide polymorphisms (SNPs) in the VKORC1, CYP4F2, and GGCX genes have been linked to clinical outcomes, such as bleeding and cardiovascular diseases. This study aimed to investigate the association between specific polymorphisms in these genes and the risk of developing the first episode of acute ischemic stroke in patients without a known embolic source. This retrospective, cross-sectional, observational, analytical, case-control study included adult patients diagnosed with acute ischemic stroke. The SNPs in VKORC1 rs9923231, CYP4F2 rs2108622, GGCX rs11676382 genes were genotyped and analyzed together with the demographic and clinical factors of the 2 groups of patients. The presence of SNPs in VKORC1 or CYP4F2 genes significantly increased the risk of ischemic stroke in the context of smoking, arterial hypertension, and carotid plaque burden. The multivariate logistic model revealed that smoking (odds ratio [OR] = 3.920; P < .001), the presence of carotid plaques (OR = 2.661; P < .001) and low-density lipoprotein cholesterol values >77 mg/dL (OR = 2.574; P < .001) were independently associated with stroke. Polymorphisms in the VKORC1 and CYP4F2 genes may increase the risk of ischemic stroke in patients without a determined embolic source. Smoking, the presence of carotid plaques, and high low-density lipoprotein cholesterol levels were reconfirmed as important factors associated with ischemic stroke.

Sex differences in eicosanoid formation and metabolism: A possible mediator of sex discrepancies in cardiovascular diseases

Arachidonic acid is metabolized by cyclooxygenase, lipoxygenase, and cytochrome P450 enzymes to produce prostaglandins, leukotrienes, epoxyeicosatrienoic acids (EETs), and hydroxyeicosatetraenoic acids (HETEs), along with other eicosanoids. Eicosanoids have important physiological and pathological roles in the body, including the cardiovascular system. Evidence from several experimental and clinical studies indicates differences in eicosanoid levels, as well as in the activity or expression levels of their synthesizing and metabolizing enzymes between males and females. In addition, there is a clear state of gender specificity in cardiovascular diseases (CVD), which tend to be more common in men compared to women, and their risk increases significantly in postmenopausal women compared to younger women. This could be largely attributed to sex hormones, as androgens exert detrimental effects on the heart and blood vessels, whereas estrogen exhibits cardioprotective effects. Many of androgen and estrogen effects on the cardiovascular system are mediated by eicosanoids. For example, androgens increase the levels of cardiotoxic eicosanoids like 20-HETE, while estrogens increase the levels of cardioprotective EETs. Thus, sex differences in eicosanoid levels in the cardiovascular system could be an important underlying mechanism for the different effects of sex hormones and the differences in CVD between males and females. Understanding the role of eicosanoids in these differences can help improve the management of CVD.

Metabolomics and metabolites in ischemic stroke

Stroke is a major reason for disability and the second highest cause of death in the world. When a patient is admitted to a hospital, it is necessary to identify the type of stroke, and the likelihood for development of a recurrent stroke, vascular dementia, and depression. These factors could be determined using different biomarkers. Metabolomics is a very promising strategy for identification of biomarkers. The advantage of metabolomics, in contrast to other analytical techniques, resides in providing low molecular weight metabolite profiles, rather than individual molecule profiles. Technically, this approach is based on mass spectrometry and nuclear magnetic resonance. Furthermore, variations in metabolite concentrations during brain ischemia could alter the principal neuronal functions. Different markers associated with ischemic stroke in the brain have been identified including those contributing to risk, acute onset, and severity of this pathology. In the brain, experimental studies using the ischemia/reperfusion model (IRI) have shown an impaired energy and amino acid metabolism and confirmed their principal roles. Literature data provide a good basis for identifying markers of ischemic stroke and hemorrhagic stroke and understanding metabolic mechanisms of these diseases. This opens an avenue for the successful use of identified markers along with metabolomics technologies to develop fast and reliable diagnostic tools for ischemic and hemorrhagic stroke.

20-HETE-promoted cerebral blood flow autoregulation is associated with enhanced pericyte contractility

We previously reported that deficiency in 20-HETE or CYP4A impaired the myogenic response and autoregulation of cerebral blood flow (CBF) in rats. The present study demonstrated that CYP4A was coexpressed with alpha-smooth muscle actin (α-SMA) in vascular smooth muscle cells (VSMCs) and most pericytes along parenchymal arteries (PAs) isolated from SD rats. Cell contractile capabilities of cerebral VSMCs and pericytes were reduced with a 20-HETE synthesis inhibitor, HET0016, but restored with 20-HETE analog WIT003. Similarly, intact myogenic responses of the middle cerebral artery and PA of SD rats decreased with HET0016 and were rescued by WIT003. The myogenic response of the PA was abolished in SS and was restored in SS.BN5 and SS.Cyp4a1 rats. HET0016 enhanced CBF and impaired its autoregulation in the surface and deep cortex of SD rats. These results demonstrate that 20-HETE has a direct effect on cerebral mural cell contractility that may play an essential role in controlling cerebral vascular function.

Conflicting Roles of 20-HETE in Hypertension and Stroke

Hypertension is the most common modifiable risk factor for stroke, and understanding the underlying mechanisms of hypertension and hypertension-related stroke is crucial. 20-hydroxy-5, 8, 11, 14-eicosatetraenoic acid (20-HETE), which plays an important role in vasoconstriction, autoregulation, endothelial dysfunction, angiogenesis, inflammation, and blood-brain barrier integrity, has been linked to hypertension and stroke. 20-HETE can promote hypertension by potentiating the vascular response to vasoconstrictors; it also can reduce blood pressure by inhibition of sodium transport in the kidney. The production of 20-HETE is elevated after the onset of both ischemic and hemorrhagic strokes; on the other hand, subjects with genetic variants in CYP4F2 and CYP4A11 that reduce 20-HETE production are more susceptible to stroke. This review summarizes recent genetic variants in CYP4F2, and CYP4A11 influencing 20-HETE production and discusses the role of 20-HETE in hypertension and the susceptibility to the onset, progression, and prognosis of ischemic and hemorrhagic strokes.

Molecular Functionality of Cytochrome P450 4 (CYP4) Genetic Polymorphisms and Their Clinical Implications

Enzymes in the cytochrome P450 4 (CYP4) family are involved in the metabolism of fatty acids, xenobiotics, therapeutic drugs, and signaling molecules, including eicosanoids, leukotrienes, and prostanoids. As CYP4 enzymes play a role in the maintenance of fatty acids and fatty-acid-derived bioactive molecules within a normal range, they have been implicated in various biological functions, including inflammation, skin barrier, eye function, cardiovascular health, and cancer. Numerous studies have indicated that genetic variants of CYP4 genes cause inter-individual variations in metabolism and disease susceptibility. Genetic variants of CYP4A11, 4F2 genes are associated with cardiovascular diseases. Mutations of CYP4B1, CYP4Z1, and other CYP4 genes that generate 20-HETE are a potential risk for cancer. CYP4V2 gene variants are associated with ocular disease, while those of CYP4F22 are linked to skin disease and CYP4F3B is associated with the inflammatory response. The present study comprehensively collected research to provide an updated view of the molecular functionality of CYP4 genes and their associations with human diseases. Functional analysis of CYP4 genes with clinical implications is necessary to understand inter-individual variations in disease susceptibility and for the development of alternative treatment strategies.

A prospective study of serum metabolites and risk of ischemic stroke

OBJECTIVE

To identify promising blood-based biomarkers and novel etiologic pathways of disease risk, we applied an untargeted serum metabolomics profiling in a community-based prospective study of ischemic stroke (IS).

METHODS

In 3,904 men and women from the Atherosclerosis Risk In Communities study, Cox proportional hazard models were used to estimate the association of incident IS with the standardized level of 245 fasting serum metabolites individually, adjusting for age, sex, race, field center, batch, diabetes, hypertension, current smoking status, body mass index, and estimated glomerular filtration rate. Validation of results was carried out in an independent sample of 114 IS cases and 112 healthy controls.

RESULTS

Serum levels of 2 long-chain dicarboxylic acids, tetradecanedioate and hexadecanedioate, were strongly correlated (r = 0.88) and were associated with incident IS after adjusting for covariates (hazard ratio [95% confidence interval (CI)] 1.11 [1.06-1.16] and 1.12 [1.07-1.17], respectively; p < 0.0001). Analyses by IS subtypes suggested that these associations were specific to cardioembolic stroke (CES). Associations of tetradecanedioate and hexadecanedioate with IS were independently confirmed (odds ratio [95% CI] 1.76 [1.21; 2.56] and 1.60 [1.11; 2.32], respectively).

CONCLUSION

Two serum long-chain dicarboxylic acids, metabolic products of ω-oxidation of fatty acids, were associated with IS and CES independently of known risk factors. Pathways related to intracellular hexadecanedioate synthesis or those involved in its clearance from the circulation may mediate IS risk. These results highlight the potential of metabolomics to discover novel circulating biomarkers for stroke and to unravel novel pathways for IS and its subtypes.

Genetics and Genomics of Acute Neurologic Disorders

Neurologic diseases and injuries are complex and multifactorial, making risk prediction, targeted treatment modalities, and outcome prognostication difficult and elusive. Genetics and genomics have affected clinical practice in many aspects in medicine, particularly cancer treatment. Advancements in knowledge of genetic and genomic variability in neurologic disease and injury are growing rapidly. Although these data are not yet ready for use in clinical practice, research continues to progress and elucidate information that eventually will provide answers to complex neurologic questions and serve as a platform to provide individualized care plans aimed at improving outcomes. This article provides a focused review of relevant literature on genetics, genomics, and common complex neurologic disease and injury likely to be seen in the acute care setting.

Cytochrome P450 family 4 subfamily F member 2 (CYP4F2) rs1558139, rs2108622 polymorphisms and susceptibility to several cardiovascular and cerebrovascular diseases

Background

Inconsistent conclusions have been reported for the genetic relationship between CYP4F2 (Cytochrome P450 Family 4 Subfamily F Member 2) polymorphisms and the susceptibility to cardiovascular and cerebrovascular diseases.

Methods

We performed a meta-analysis to assess the potential role of rs1558139 C/T and rs2108622 G/A polymorphisms of CYP4F2 in the risks of cardiovascular and cerebrovascular diseases. The retrieval of four databases, including PubMed, Web of Science (WOS), China National Knowledge Infrastructure (CNKI) and WANFANG DATA, was conducted. Mantel-Haenszel statistics for association test, Cochran’s Q statistic, sensitivity analysis for heterogeneity assessment, and Begg’s/Egger’s tests for publication bias evaluation were performed under allele, homozygote, heterozygote, dominant, and recessive models, respectively.

Results

A total of 597 articles were initially obtained by database searching, and twenty eligible articles were finally included. For rs1558139, a decreased risk of cardiovascular and cerebrovascular diseases was observed in the overall meta-analysis and in “hypertension”, “population-based” and “male” subgroups under models of T vs. C, CT vs. CC, and CT + TT vs. CC [all P values in association tests < 0.05, odds ratio (OR) < 1]. For rs2108622, a decreased coronary artery disease (CAD) risk was observed in the subgroup meta-analysis based on disease type under all genetic models (all P values in association tests < 0.05, OR< 1). Begg’s/Egger’s tests excluded the potential publication bias, while sensitivity analysis data supported the stability of the above results.

Conclusion

C/T genotype of CYP4AF2 rs1558139 may be linked to the decreased risk of hypertension in the male patients of Asian populations, while CYP4F2 rs2108622 is likely associated with reduced susceptibility to CAD.

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0763-y) contains supplementary material, which is available to authorized users.

Cerebral Autoregulation in Hypertension and Ischemic Stroke: A Mini Review

Aging and chronic hypertension are associated with dysfunction in vascular smooth muscle, endothelial cells, and neurovascular coupling. These dysfunctions induce impaired myogenic response and cerebral autoregulation, which diminish the protection of cerebral arterioles to the cerebral microcirculation from elevated pressure in hypertension. Chronic hypertension promotes cerebral focal ischemia in response to reductions in blood pressure that are often seen in sedentary elderly patients on antihypertensive therapy. Cerebral autoregulatory dysfunction evokes Blood-Brain Barrier (BBB) leakage, allowing the circulating inflammatory factors to infiltrate the brain to activate glia. The impaired cerebral autoregulation-induced inflammatory and ischemic injury could cause neuronal cell death and synaptic dysfunction which promote cognitive deficits. In this brief review, we summarize the pathogenesis and signaling mechanisms of cerebral autoregulation in hypertension and ischemic stroke-induced cognitive deficits, and discuss our new targets including 20-Hydroxyeicosatetraenoic acid (20-HETE), Gamma-Adducin (Add3) and Matrix Metalloproteinase-9 (MMP-9) that may contribute to the altered cerebral vascular function.

Joint Effects of GWAS SNPs in Coagulation System Confer Risk to Hypertensive Intracerebral Hemorrhage

Recent genome-wide association studies (GWAS) have identified numerous single nucleotide polymorphisms (SNPs) associated with coagulation system, including hemostatic factors and hematological phenotypes. However, few articles described the relationships between these SNPs and the risk of hemorrhagic stroke. The aim of our study was to evaluate the roles of these SNPs as risk factors and survival predictors for hemorrhagic stroke. Thirteen SNPs from GWAS in coagulation system were genotyped in a Chinese Han population including 1000 patients with hemorrhagic stroke (intracerebral hemorrhage, ICH = 743; subarachnoid hemorrhage, SAH = 257) and 1044 population-based controls. The associations between the genetics risk score (GRS) and risk of hemorrhagic stroke as well as post-stroke adverse outcomes were determined. No individual SNP was associated with the risk of hemorrhagic stroke. The GRS was calculated by summing the number of risk alleles of each SNP, and a total of 13 SNPs were included. Meanwhile, the GRS cutoffs values were defined to be close to quartiles or tertiles in control subjects. For quartiles, individuals with GRS about 8-9, 10-11, ≥12 had 1.28 (OR 1.28, 95% CI 0.98-1.68, p = 0.067)-, 1.36 (OR 1.36, 95% CI 1.04-1.79, p = 0.026)-, 1.53 (OR 1.53, 95% CI 1.13-2.07, p = 0.006)-fold increase in ICH risk compared to those with GRS ≤7, respectively; for tertiles, individuals with GRS about GRS 9-10, ≥11 had 0.98 (OR 0.98, 95% CI 0.78-1.23, p = 0.067)- and 1.26 (OR 1.26, 95% CI 1.00-1.59, p = 0.048)-fold increase in ICH risk compared to those with GRS ≤8, respectively. Further stratification analyses indicated that this association was only found in hypertensive ICH subjects. However, no statistical difference was found in the volume of hematoma, activities of daily living scale as well as hospital death in the ICH patients based on GRS values. Joint effects of SNPs associated with low coagulation factor levels might confer risk to ICH patients with hypertension. However, the clinical value on risk stratification and survival prediction was limited.

Molecular mechanisms and cell signaling of 20-hydroxyeicosatetraenoic acid in vascular pathophysiology

Cytochrome P450s enzymes catalyze the metabolism of arachidonic acid to epoxyeicosatrienoic acids (EETs), dihydroxyeicosatetraenoic acid and hydroxyeicosatetraeonic acid (HETEs). 20-HETE is a vasoconstrictor that depolarizes vascular smooth muscle cells by blocking K+ channels. EETs serve as endothelial derived hyperpolarizing factors. Inhibition of the formation of 20-HETE impairs the myogenic response and autoregulation of renal and cerebral blood flow. Changes in the formation of EETs and 20-HETE have been reported in hypertension and drugs that target these pathways alter blood pressure in animal models. Sequence variants in CYP4A11 and CYP4F2 that produce 20-HETE, UDP-glucuronosyl transferase involved in the biotransformation of 20-HETE and soluble epoxide hydrolase that inactivates EETs are associated with hypertension in human studies. 20-HETE contributes to the regulation of vascular hypertrophy, restenosis, angiogenesis and inflammation. It also promotes endothelial dysfunction and contributes to cerebral vasospasm and ischemia-reperfusion injury in the brain, kidney and heart. This review will focus on the role of 20-HETE in vascular dysfunction, inflammation, ischemic and hemorrhagic stroke and cardiac and renal ischemia reperfusion injury.

Interactions Among CYP2C8, EPHX2, and CYP4A11 Variants and CYP Plasma Metabolite Levels in Ischemic Stroke

Aim: To better understand the relationship between the interactions among rs17110453, rs751141, and rs9333025 variants and plasma levels of cytochrome P450 (CYP) metabolites, i.e., 20-hydroxyeicosatetraenoic acid (20-HETE), epoxyeicosatrienoic acids (EETs), and dihydroxyeicosatrienoic acids (DiHETEs) in ischemia stroke (IS).

Methods: We measured plasma CYP metabolite levels in 218 acute IS cases and 126 controls, and a subset of samples were assessed to further understand the association between relevant variants and IS risk in our previous study. We assessed the associations between variant interactions and levels of 20-HETE, EETs, and DiHETEs as well as the associations between levels of 20-HETE, EETs, and DiHETEs and IS risk after adjusting for other potential confounders. Furthermore, the association between variant interactions and IS risk after adjusting for other covariates, including CYP metabolites levels, was evaluated.

Results: The interactions among variants rs17110453, rs751141, and rs9333025 were significantly associated with high 20-HETE, high DiHETEs, and low EETs after adjusting for the status of diabetes mellitus and hypertension. High 20-HETE, high DiHETEs, and low EETs were independent risk factors for IS after adjusting for hypertension, diabetes mellitus, and the interactions among rs17110453, rs751141, and rs9333025. Furthermore, the interactions among rs17110453, rs751141, and rs9333025 were significantly associated with a higher risk of IS after adjusting for CYP metabolites (OR= 2.02, 95% CI: 1.28–5.27, P = 0.007).

Conclusion: The association between the interactions among rs17110453, rs751141, and rs9333025 and IS risk in Chinese population may be partly but not exclusively mediated by plasma levels of 20-HETE, EETs, and DHETs. Further well-designed studies are warranted to replicate this finding.

Interaction Between CYP4F2 rs2108622 and CPY4A11 rs9333025 Variants Is Significantly Correlated with Susceptibility to Ischemic Stroke and 20-Hydroxyeicosatetraenoic Acid Level

AIMS

To investigate the association of four variants of two CYP ω-hydroxylase genes and 20-hydroxyeicosatetraenoic acid (HETE) levels with ischemic stroke (IS) and whether gene-gene interactions between these genes increase the risk of IS.

METHODS

Three hundred ninety-six patients with IS and 378 controls were genotyped for rs2269231, rs9333025, rs2108622, and rs3093135. Gene-gene interactions were analyzed using generalized multifactor dimensionality reduction (GMDR) methods. The 20-HETE levels was measured in 218 IS patients and 126 controls.

RESULTS

The frequency of the GG genotype of rs9333025 was significantly higher in IS patients than in controls (p < 0.001). The GMDR analysis showed a significant gene-gene interaction between rs9333025 and rs2108622 (p = 0.0116). This gene-gene interaction predicted a significantly higher risk of IS in individuals carrying the genotypes of rs9333025 GG and rs2108622 GG (odds ratio = 1.92, 95% confidence interval = 1.12-4.26, p = 0.007). The plasma levels of 20-HETE were significantly higher in IS patients than in controls, and IS patients carrying the genotype combination of rs9333025 GG and rs2108622 GG had higher 20-HETE levels than IS patients with other combinations of the two variants.

CONCLUSION

CYP4A1l rs9333025 GG and CYP4F2 rs2108622 GG two-loci interaction significantly increases the risk for IS and an elevated 20-HETE level.

CYP Genetic Variants, CYP Metabolite Levels, and Symptomatic Carotid Stenosis in Ischemic Stroke Patients

AIM

To evaluate the relationship between CYP genetic polymorphisms and CYP metabolite levels with carotid artery stenosis in acute ischemic stroke (IS) patients.

METHODS

Eleven single nucleotide polymorphisms (SNPs) of seven CYP genes were genotyped in 136 IS patients with carotid stenosis and 158 patients without carotid stenosis. CYP plasma metabolite levels [20-hydroxyeicosatetraenoic acid (HETE), total epoxyeicosatrienoic acids (EETs), and dihydroxyeicosatrienoic acids (DiHETEs)] were assessed in a subsample of 90 patients with carotid stenosis and 96 patients without carotid stenosis. We evaluated the relationship between assessed variants and carotid stenosis risk, variants with CYP metabolite levels, and variants in mediating the differences of CYP metabolite levels between patients with carotid stenosis and those without. Additionally, gene-gene interactions were analyzed to assess the interactive role of the assessed variants in affecting CYP metabolite levels and risk of carotid stenosis.

RESULTS

The genotypes of rs17110453CC, rs751141GG, and rs9333025GG were significantly associated with carotid stenosis risk. Also these polymorphisms were associated with CYP plasma metabolite levels in patients with carotid stenosis. There was a significant gene-gene interaction between rs17110453 and rs9333025 in affecting the risk of carotid stenosis. Patients with rs17110453CC and rs9333025GG had a significantly higher risk of carotid stenosis than those with 17110453AA and rs9333025AA (OR=2.12, 95% CI: 1.13-7.26, P=0.013).

CONCLUSIONS

Specific CYP450 gene SNPs and their interactions are associated with CYP450 plasma metabolite levels, which may partially explain their associations with carotid stenosis. Further studies are needed to validate our findings.

Correlation between CYP4F2 gene rs2108622 polymorphism and susceptibility to ischemic stroke

OBJECTIVE

To conduct a meta-analysis for the correlation between cytochrome P450 4F2 (CYP4F2) rs2108622 (V433M) gene polymorphism and ischemic stroke.

METHODS

We retrieved the case-control studies on the correlation between CYP4F2 V433M polymorphism and ischemic stroke included in domestic and international databases before January 2015 and selected the best genetic model, using RevMan 5.2 software for meta-analysis. According to the heterogeneity test results of selected literature, the effect model of consolidated data was selected, and the combined OR and 95% CI were calculated.

RESULTS

A total of six documents were included. Recessive model (VM + MM vs. VV) was selected as the best genetic model. The combined results showed that: compared with wild-type VV, there are significant association between ischemic stroke and CYP4F2 polymorphism (OR merge = 1.37, 95% CI: 1.21~1.54, P < 0.001).

CONCLUSION

CYP4F2 V433M may be the susceptibility gene for ischemic stroke.

Cytochrome 4A11 Genetic Polymorphisms Increase Susceptibility to Ischemic Stroke and Associate with Atherothrombotic Events After Stroke in Chinese

To evaluate the associations between four single-nucleotide polymorphisms (SNPs) in CYP4A11 and CYP4F2 and ischemic stroke (IS), and between these variants and atherothrombotic events after stroke. IS patients (n=396) and controls (n=378) were genotyped for two CYP4A11 SNPs (rs2269231 and rs9333025) and two CYP4F2 SNPs (rs2108622 and rs3093135). Patients were followed up for 12 months after the stroke for the atherothrombotic events. The frequency of the rs9333025 GG genotype was significantly higher in IS patients than in controls. Logistic regression analysis showed that the presence of rs9333025 GG in patients was associated with significantly higher risk of IS. Cox regression analysis revealed that the rs9333025 GG genotype was an independent risk factor for atherothrombotic events after stroke. The rs9333025 GG genotype increases patients' susceptibility to IS and is associated with high frequencies of atherothrombotic events in stroke patients.

Cytochrome P450 eicosanoids in hypertension and renal disease

PURPOSE OF REVIEW

Cytochrome (CYP) P450 metabolites of arachidonic acid, 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) contribute to the regulation of renal tubular and vascular function. This review highlights the results of the recent genetic studies in humans and rodent models, indicating that these eicosanoids participate in the control of blood pressure (BP), chronic kidney disease (CKD), renal ischemia-reperfusion injury (IRI) and polycystic kidney disease (PKD).

RECENT FINDINGS

Endogenous 20-HETE has been reported to play an essential role in the myogenic and tubuloglomerular feedback responses in the afferent arteriole, and a deficiency of 20-HETE contributes to the development of hypertension and renal injury in Dahl S rats. Mutations in CYP4A11 and CYP4F2 have been linked to elevated BP in humans. EETs have been shown to regulate epithelial sodium channel in the collecting duct, lower BP and have renoprotective properties. 20-HETE also opposes the development of CKD and IRI, and may play a role in PKD.

SUMMARY

These studies indicate that CYP P450 metabolites of arachidonic acid play an important role in the control of BP, CKD, AKI and PKD. Drugs targeting these pathways could be useful in the treatment of IRI and CKD.

Impaired myogenic response and autoregulation of cerebral blood flow is rescued in CYP4A1 transgenic Dahl salt-sensitive rat

We have reported that a reduction in renal production of 20-HETE contributes to development of hypertension in Dahl salt-sensitive (SS) rats. The present study examined whether 20-HETE production is also reduced in the cerebral vasculature of SS rats and whether this impairs the myogenic response and autoregulation of cerebral blood flow (CBF). The production of 20-HETE, the myogenic response of middle cerebral arteries (MCA), and autoregulation of CBF were compared in SS, SS-5(BN) rats and a newly generated CYP4A1 transgenic rat. 20-HETE production was 6-fold higher in cerebral arteries of CYP4A1 and SS-5(BN) than in SS rats. The diameter of the MCA decreased to 70 ± 3% to 65 ± 6% in CYP4A1 and SS-5(BN) rats when pressure was increased from 40 to 140 mmHg. In contrast, the myogenic response of MCA isolated from SS rats did not constrict. Administration of a 20-HETE synthesis inhibitor, HET0016, abolished the myogenic response of MCA in CYP4A1 and SS-5(BN) rats but had no effect in SS rats. Autoregulation of CBF was impaired in SS rats compared with CYP4A1 and SS-5(BN) rats. Blood-brain barrier leakage was 5-fold higher in the brain of SS rats than in SS-5(BN) and SS.CYP4A1 rats. These findings indicate that a genetic deficiency in the formation of 20-HETE contributes to an impaired myogenic response in MCA and autoregulation of CBF in SS rats and this may contribute to vascular remodeling and cerebral injury following the onset of hypertension.

Urinary CYP eicosanoid excretion correlates with glomerular filtration in African-Americans with chronic kidney disease

Previous studies have indicated that cytochrome P450 (CYP) metabolites of arachidonic acid (AA), i.e., 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs), play an important role in the regulation of renal tubular and vascular function. The present study for the first time profiled HETEs and epoxygenase derived dihydroxyeicosatetraenoic acid diHETEs levels in spot urines and plasma in 262 African American patients from the University of Mississippi Chronic Kidney Disease Clinic and 31 African American controls. Significant correlations in eGFR and urinary 20-HETE/creatinine and 19-HETE/creatinine levels were observed. The eGFR increased by 17.47 [p=0.001] and 60.68 [(p=0.005]ml/min/for each ng/mg increase in 20-HETE and 19-HETE levels, respectively. Similar significant positive associations were found between the other urinary eicosanoids and eGFR and also with 19-HETE/urine creatinine concentration and proteinuria. We found that approximately 80% of plasma HETEs and 30% diHETEs were glucuronidated and the fractional excretion of 20-HETE was less than 1%. These results suggest that there is a significant hepatic source of urinary 20-HETE glucuronide and EETs with extensive renal biotransformation to metabolites which may play a role in the pathogenesis of CKD.

Association between the CYP4A11 T8590C variant and essential hypertension: new data from Han Chinese and a meta-analysis

Objective

CYP4A11 oxidizes endogenous arachidonic acid to 20-hydroxyeicosatetraenoic acid, a renal vasoconstrictor and natriuretic in humans. Previous studies demonstrated an association between a functional variant (T8590C) of CYP4A11 and essential hypertension, though with conflicting results. To elucidate this relationship, a case-control study and meta-analysis were performed to assess the possible association of essential hypertension with CYP4A11 genetic variations.

Methods

Associations between the T8590C polymorphism and essential hypertension were examined in 328 unrelated cases and 297 age-matched controls in Han Chinese individuals. High-resolution melting was used to identify the CYP4A11 variant. To further investigate the association, we conducted a meta-analysis including eight studies published previously in July 2012.

Results

The frequency of the CYP4A11 T8590C polymorphism showed no significant difference between cases and controls (all P>0.05). However, the meta-analysis showed that the CYP4A11 T8590C polymorphism may increase the risk of essential hypertension in an additive model (OR: 1.15, 95% CI: 1.02–1.29, P = 0.02), a dominant model (OR: 1.06, 95% CI: 1.01–1.32, P = 0.03), a recessive model (OR: 1.52, 95% CI: 1.15–2.02, P = 0.003) and a homozygote contrast (OR: 1.38, 95% CI: 1.07–1.78, P = 0.01). Also, a significant relationship was observed among Caucasians in the additive model, the homozygote contrast, the recessive model and the dominant model (all P<0.05). However, no association was observed in an Asian population (all P>0.05).

Conclusions

This meta-analysis suggests there is a significant association between the CYP4A11 T8590C variant and essential hypertension, especially in Caucasians. The case-control study did not find a significant association among the Han Chinese population, but the controls were poorly matched and meaningful conclusions cannot therefore be made. Further large-scale studies are needed to clarify whether the CYP4A11 T8590C polymorphism is associated with hypertension risk in Asians or has a gender-specific effect.

Rs2200733 and rs10033464 on chromosome 4q25 confer risk of cardioembolic stroke: an updated meta-analysis

A recent genome-wide association study elucidated that 4q25 was implicated in ischemic stroke, but subsequent studies showed inconsistent results. In order to get coincident conclusion, we investigated two SNPs (rs2200733, rs10033464) on chromosome 4q25 in 1,388 stroke patients and 1,629 controls from Chinese Han population and then performed a meta-analysis. Although we failed to detect any association between 4q25 and stroke in our case-control study, meta-analysis revealed that rs2200733 showed association with overall stroke (OR 1.18, 95 % CI 1.08-1.27), but not for rs10033464. Subsequently subgroup analysis indicated that both rs2200733 and rs10033464 conferred increased risk for cardioembolic stroke (CE stroke) (for rs2200733, OR 1.38, 95 % CI 1.26-1.51; for rs10033464, OR 1.14, 95 % CI 1.02-1.26), while rs2200733 was marginal associated with non-CE stroke (OR 1.09, 95 % CI 1.02-1.16). our results demonstrated that two SNPs (rs2200733 and rs1003346) on chromosome 4q25 were limited to the stroke of cardioembolic etiology. To confirm this conclusion, well-designed studies with larger sample size involving case-control populations with homogeneous ancestry warrant to be conducted in the future.

Mechanisms for the prevention of vitamin E excess

The liver is at the nexus of the regulation of lipoprotein uptake, synthesis, and secretion, and it is the site of xenobiotic detoxification by cytochrome P450 oxidation systems (phase I), conjugation systems (phase II), and transporters (phase III). These two major liver systems control vitamin E status. The mechanisms for the preference for α-tocopherol relative to the eight naturally occurring vitamin E forms largely depend upon the liver and include both a preferential secretion of α-tocopherol from the liver into the plasma for its transport in circulating lipoproteins for subsequent uptake by tissues, as well as the preferential hepatic metabolism of non-α-tocopherol forms. These mechanisms are the focus of this review.

Association analysis of polymorphisms in ROCK2 with cardiovascular disease in a Chinese population

Background

Rho-kinase (ROCK) has been shown to play an important role in cardiovascular disease such as coronary artery disease (CAD) and hypertension. Recently, common variants of ROCK2 have been reported to influence blood pressure, but the relationship between common ROCK2 variants and cardiovascular disease has not been extensively studied in the Chinese population.

Methods

To derive a more precise estimation of their relationship, we screened for the common variants by direct sequencing of all exons of ROCK2, and then we performed genetic association analyses in a CAD case–control study, including a total of 1344 cases and 1267 ethnically and geographically matched controls.

Results

Unconditional logistic regression showed that no significant association between common variants in the coding region of ROCK2 and CAD was observed in our study (for rs978906, OR = 0.92, 95% CI 0.72–1.20 and P = 0.63; for rs2230774, OR = 0.90, 95% CI 0.70–1.16 and P = 0.47; for rs56304104, OR = 0.97, 95% CI 0.70–1.31 and P = 0.83; respectively).

Conclusions

The relationship between the ROCK2 polymorphisms and cardiovascular disease risk cannot be entirely discounted and warrants further evaluation in a large population.

Polymorphism of HMGA1 is associated with increased risk of type 2 diabetes among Chinese individuals

AIMS/HYPOTHESIS

Variants of the high-mobility group A1 (HMGA1) gene have been shown to be associated with insulin resistance and type 2 diabetes in individuals of European origin. We aimed to determine whether this locus confers significant susceptibility to type 2 diabetes in the Han Chinese population, and thus cross-race susceptibility to type 2 diabetes.

METHODS

Polymorphisms in HMGA1 were identified by direct sequencing of genomic DNA derived from 192 Chinese participants (96 patients with type 2 diabetes and 96 controls). We then genotyped the common variant IVS5-13insC (c.136-14_136-13insC) in two other independent cohorts, including a total of 2,533 cases and 2,643 ethnically matched controls.

RESULTS

We confirmed the association of the HMGA1 variant IVS5-13insC (c.136-14_136-13insC) with type 2 diabetes with an OR of 1.34 (95% CI 1.15, 1.56, p = 0.0002 under a dominant model, and 95% CI 1.16, 1.55, p = 0.0002 under an additive model) in the Han Chinese population, corresponding to a population attributable risk fraction of 5.0%.

CONCLUSIONS/INTERPRETATION

HMGA1 is an important susceptibility locus that confers a high cross-race risk of the development of type 2 diabetes.

The functional variant V433M of the CYP4F2 and the metabolic syndrome in Swedes

BACKGROUND AND AIM

The genetic basis of Metabolic syndrome (MetS) is largely unknown but a link with salt sensitivity is recognized. The cytochrome P450 isoform 4F2 (CYP4F2) is involved in renal production of 20-hydroxyeicosatethraenoic acid (20-HETE), a natriuretic substance associated with salt sensitivity. The same enzyme is implicated in ω-hydroxylation of very long and medium chain fatty acids in the liver suggesting its possible influence on gluco-metabolic components of MetS. The aim of the present study was to evaluate the effect of CYP4F2 V433M, a functional polymorphism previously associated with hypertension via renal salt reabsorption, on the individual components of MetS and MetS itself.

METHODS

The polymorphism was genotyped in the cardiovascular cohort of the Malmö Diet and Cancer (MDC-CVA) study and successively in the Malmö Preventive Project (MPP) cohort. Different definitions of the MetS were applied.

RESULTS

In the MDC-CVA, male, but not female, CYP4F2 M433 carriers had significantly higher levels of waist, triglycerides, BP and a composite sum of MetS phenotypes (MetS score) beside lower HDL-cholesterol respect to V-homozygotes. MetS, as defined in the ATPIII and the AHA/NHLBI definitions, was more prevalent in M-carriers with respect to V-homozygotes. In the MPP cohort, significant association was detectable only for triglycerides at baseline and for Diastolic BP at reinvestigation in male M-carriers.

CONCLUSION

The initial positive association of the CYP4F2 V433M polymorphism with components of MetS and MetS itself, found in MDC-CVA, was partially denied in another large cohort. The first association either could be due to a false positive result or alternatively, different genetic background or population stratification could have hidden the effect of the polymorphism in the replication cohort.

Peripheral and central augmentation indexes in relation to the CYP4F2 polymorphisms in Chinese

OBJECTIVE

Cytochrome (CYP) 4F2 isoform is a key metabolizing enzyme for the renal 20-hydroxyeicosatetraenoic acid (20-HETE), which, as an endogenous vasoconstrictor, may influence properties of the peripheral muscular arteries and arterioles. We, therefore, investigated the CYP4F2 polymorphisms in relation to arterial wave reflections, as measured by augmentation indexes (AIx) in Chinese.

METHODS

We performed arterial measurements by SphygmoCor and genotyped three CYP4F2 polymorphisms (V433M, rs3093089, and rs3093098) by PCR-restriction fragment length polymorphism in 1421 participants enrolled in the JingNing Population study. A replication study for the V433M polymorphism was performed in 924 Chinese recruited from a workplace setting. Urinary 20-HETE concentration was determined by ELISA in a randomly selected subsample of 318 JingNing individuals.

RESULTS

In spite of the fact that genetic associations were not significant (P ≥ 0.12) in all JingNing participants, there was significant (Pint ≤ 0.02) interaction of the V433M polymorphism with sex and pulse rate in relation to peripheral and central AIx. M433 allele carriers, compared with V433V homozygotes, had significantly greater peripheral (+5.0%, P = 0.0002) and central AIx (+3.2%, P = 0.001) in 693 men. The corresponding values were +2.7% (P = 0.04) and +1.9% (P = 0.04) in 490 individuals of the top tertile of pulse rate (≥ 76 beats/min), and were +4.0% (P = 0.02) and +3.3% (P = 0.02) in 315 replication participants with a pulse rate at least 76 beats/min. Urinary 20-HETE concentration was significantly higher (P = 0.002) in M433M (2.06 ng/ml) and V433M (1.13 ng/ml) individuals than in V433V homozygotes (0.98 ng/ml).

CONCLUSION

The CYP4F2 V433M polymorphism is associated with the size of arterial wave reflections in male Chinese, or individuals with a faster pulse rate.

Arachidonic acid ω-hydroxylase CYP4A11: inter-ethnic variations in the 8590T>C loss-of-function variant

The human Cytochrome P450 4A11 (CYP4A11) is a major ω-hydroxylase involved in the regulation of blood pressure in the kidney through the conversion of arachidonic acid into 20-hydroxyeicosatetraenoic acid (20-HETE). Previous studies have reported a significant association between the 8590T>C genetic variant of CYP4A11 and hypertension. Interestingly, several population-based studies have reported ethnic differences in the prevalence of hypertension, with the highest prevalence in African populations. The aim of this work was to determine the frequency and inter-ethnic comparison of the CYP4A11 (8590T>C) functional polymorphism, in five new ethnic groups: European (99 French Caucasians), African (36 Gabonese and 50 Senegalese), South American (60 Peruvians) and North African (53 Tunisians) populations, using polymerase chain reaction-single strand conformational polymorphism and sequencing strategies. We confirmed that the CYP4A11 (8590T>C) functional polymorphism exhibits inter-ethnic frequency differences. Noteworthy, the highest 8590C allele frequency was observed in the Tunisian (30.2%), followed by Senegalese (20%) populations. In addition, the CC genotype was only found in the Gabonese and Tunisian populations (5.6% and 8.4%, respectively). These populations may be of major interest to help to clarify the linkage between hypertension and CYP4A11 (8590T>C) genotype in African populations. These findings provide data for further studies that investigate the potential association of CYP4A11 (8590T>C) variant with an incidence of hypertension genesis in respect of ethnicity.

20-hydroxyeicosatetraeonic acid: a new target for the treatment of hypertension

Arachidonic acid is metabolized by enzymes of the CYP4A and 4F families to 20-hydroxyeicosatetraeonic acid (20-HETE), which plays an important role in the regulation of renal function, vascular tone, and the long-term control of arterial pressure. In the vasculature, 20-HETE is a potent vasoconstrictor, and upregulation of the production of this compound contributes to the elevation in oxidative stress and endothelial dysfunction and the increase in peripheral vascular resistance associated with some forms of hypertension. In kidney, 20-HETE inhibits Na transport in the proximal tubule and thick ascending loop of Henle, and deficiencies in the renal formation of 20-HETE contributes to sodium retention and development of some salt-sensitive forms of hypertension. 20-HETE also has renoprotective actions and opposes the effects of transforming growth factor β to promote proteinuria and renal end organ damage in hypertension. Several new inhibitors of the synthesis of 20-HETE and 20-HETE agonists and antagonists have recently been developed. These compounds along with peroxisome proliferator-activated receptor-α agonists that induce the renal formation of 20-HETE seem to have promise as antihypertensive agents. This review summarizes the rationale for the development of drugs that target the 20-HETE pathway for the treatment of hypertension and associated cardiovascular complications.

Cytochrome P450 eicosanoids and cerebral vascular function

The eicosanoids 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs), which are generated from the metabolism of arachidonic acid by cytochrome P450 (CYP) enzymes, possess a wide array of biological actions, including the regulation of blood flow to organs. 20-HETE and EETs are generated in various cell types in the brain and cerebral blood vessels, and contribute significantly to cerebral blood flow autoregulation and the coupling of regional brain blood flow to neuronal activity (neurovascular coupling). Investigations are beginning to unravel the molecular and cellular mechanisms by which these CYP eicosanoids regulate cerebral vascular function and the changes that occur in pathological states. Intriguingly, 20-HETE and the soluble epoxide hydrolase (sEH) enzyme that regulates EET levels have been explored as molecular therapeutic targets for cerebral vascular diseases. Inhibition of 20-HETE, or increasing EET levels by inhibiting the sEH enzyme, decreases cerebral damage following stroke. The improved outcome following cerebral ischaemia is a consequence of improving cerebral vascular structure or function and protecting neurons from cell death. Thus, the CYP eicosanoids are key regulators of cerebral vascular function and novel therapeutic targets for cardiovascular diseases and neurological disorders.

Common variants of cytochrome P450 4F2 exhibit altered vitamin E-{omega}-hydroxylase specific activity

Human cytochrome P450 4F2 (CYP4F2) catalyzes the ω-hydroxylation of the side chain of tocopherols (TOH) and tocotrienols (T3), the first step in their catabolism to polar metabolites excreted in urine. CYP4F2, in conjunction with α-TOH transfer protein, results in the conserved phenotype of selective retention of α-TOH. The purpose of this work was to determine the functional consequences of 2 common genetic variants in the human CYP4F2 gene on vitamin E-ω-hydroxylase specific activity using the 6 major dietary TOH and T3 as substrate. CYP4F2-mediated ω-hydroxylase specific activity was measured in microsomal preparations from insect cells that express wild-type or polymorphic variants of the human CYP4F2 protein. The W12G variant exhibited a greater enzyme specific activity (pmol product · min(-1) · pmol CYP4F2(-1)) compared with wild-type enzyme for both TOH and T3, 230-275% of wild-type toward α, γ, and δ-TOH and 350% of wild-type toward α, γ, and δ-T3. In contrast, the V433M variant had lower enzyme specific activity toward TOH (42-66% of wild type) but was without a significant effect on the metabolism of T3. Because CYP4F2 is the only enzyme currently shown to metabolize vitamin E in humans, the observed substrate-dependent alterations in enzyme activity associated with these genetic variants may result in alterations in vitamin E status in individuals carrying these mutations and constitute a source of variability in vitamin E status.