Genetic variation in MDR1, LPL and eNOS genes and the response to atorvastatin treatment in ischemic stroke

The Influence of Endothelial Nitric Oxide Synthase (eNOS) Genetic Polymorphisms on Cholesterol Blood Levels Among Type 2 Diabetic Patients on Atorvastatin Therapy

Background:

Endothelial nitric oxide synthase (eNOS) plays a major role in the response of anti-hypercholesterol statin drugs. Genetic polymorphisms in the eNOS gene affect the activity of eNOS thereby modulating the statin response.

Objectives:

This study investigated the influence of major functional eNOS gene polymorphisms (rs2070744, rs1799983, and rs61722009) on the lipid profile of type 2 diabetes mellitus (T2DM) Jordanian patients treated with atorvastatin.

Methods:

The sample comprised 103 T2DM patients who attended the diabetes clinic of Jordan University Hospital. The T2DM patients had regularly been taking 20 mg atorvastatin. The atorvastatin response was calculated by measuring the lipid profile before and after three months of atorvastatin treatment. The eNOS genotypes of the subjects were analyzed using polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) assay.

Results:

No significant association was found between eNOS genetic polymorphisms and the response to atorvastatin (ANOVA, p > 0.05). In addition, no significant difference in the frequency of eNOS genotypes was found between T2DM patients and healthy subjects. However, patients with eNOS rs1799983, 4a/4a, and rs61722009 G/G genotypes showed significantly lower levels of baseline total cholesterol (TC) and low density lipoprotein (LDL) than did patients carrying the rs1799983 4b/4b or rs61722009 T/T genotype (p < 0.05). The eNOS rs1799983 and rs61722009 polymorphisms were in complete linkage disequilibrium (D' = 1).

Conclusion:

Although no association was found between eNOS genetic polymorphisms and atorvastatin response, there was a significant association between the rs1799983 and rs61722009 genotypes and baselines levels of TC and LDL in Jordanian T2DM patients. These genetic variants affect cholesterol levels and may play a role in the susceptibility to cardiovascular diseases in T2DM patients. Further studies are needed to validate these findings.

Prestroke statins use reduces oxidized low density lipoprotein levels and improves clinical outcomes in patients with atrial fibrillation related acute ischemic stroke

Background

Atrial fibrillation (AF) is a common cause of cerebral infarction, which could lead to endothelial dysfunction, increased reactive oxygen species (ROS) and oxidized low density lipoprotein (Ox-LDL).AF is associated with higher mortality and more severe neurologic disability. Statins may exert neuroprotective effects that are independent of LDL-C lowering. The purpose of our study was to investigate whether prestroke statins use could reduce plasma Ox-LDL levels and improve clinical outcomes in patients with AF-related acute ischemic stroke (AIS).

Methods

This was a multicenter prospective study that involved four medical centers, 242 AIS patients with AF were identified, who underwent a comprehensive clinical investigation and a 72 h-Holter electrocardiogram monitoring. All patients were divided into two groups: prestroke statins use and no prestroke statins use groups, who were followed up for 3 months. Plasma Ox-LDL levels were measured using enzyme-linked immunosorbent assay (ELISA) on admission and at 3 months. The outcome was death, major disability (modified Rankin Scale score ≥ 3), and composite outcome (death/major disability) at 3 months after AIS.

Results

One hundred thirty-six patients were in no prestroke statins use group, and 106 in prestroke statins use group. Plasma Ox-LDL levels were significantly lower in prestroke statins use than in no prestroke statins use on admission and at 3 months (P < 0.001). Plasma Ox-LDL levels on admission were associated with 3-month mortality [adjusted odds ratio (OR), 1.05; 95% confidence interval (CI), 0.99–1.12; P = 0.047]. In fully adjusted models, prestroke statins use was associated with reduced 3-month mortality [adjusted OR, 0.38; 95% CI, 0.16–0.91; P = 0.031)], major disability (adjusted OR, 0.38; 95% CI, 0.15–0.99; P = 0.047), and composite outcome (adjusted OR, 0.31; 95% CI, 0.17–0.74; P = 0.009).

Conclusions

Prestroke statins use can reduce plasma Ox-LDL levels and improve clinical outcomes in patients with AF-related AIS.

Influences of genetic variants on stroke recovery: a meta-analysis of the 31,895 cases

Background

The influences of genetic variants on functional clinical outcomes following stroke are unclear. In order to reliably quantify these influences, we undertook a comprehensive meta-analysis of outcomes after acute intracerebral haemorrhage (ICH) or ischaemic stroke (AIS) in relation to different genetic variants.

Methods

PubMed, PsycInfo, Embase and Medline electronic databases were searched up to January 2019. Outcomes, defined as favourable or poor, were assessed by validated scales (Barthel index, modified Rankin scale, Glasgow outcome scale and National Institutes of Health stroke scale).

Results

Ninety-two publications comprising 31,895 cases met our inclusion criteria. Poor outcome was observed in patients with ICH who possessed the APOE4 allele: OR =2.60 (95% CI = 1.25–5.41, p = 0.01) and in AIS patients with the GA or AA variant at the BDNF-196 locus: OR = 2.60 (95% CI = 1.25–5.41, p = 0.01) or a loss of function allele of CYP2C19: OR = 2.36 (95% CI = 1.56–3.55, p < 0.0001). Poor outcome was not associated with APOE4: OR = 1.02 (95% CI = 0.81–1.27, p = 0.90) or IL6-174 G/C: OR = 2.21 (95% CI = 0.55–8.86, p = 0.26) in patients with AIS.

Conclusions

We demonstrate that recovery of AIS was unfavourably associated with variants of BDNF and CYP2C19 genes whilst recovery of ICH was unfavourably associated with APOE4 gene.

Electronic supplementary material

The online version of this article (10.1007/s10072-019-04024-w) contains supplementary material, which is available to authorized users.

Pharmacogenetic relevance of endothelial nitric oxide synthase polymorphisms and gene interactions

Endothelial nitric oxide synthase (NOS3) is a key enzyme responsible for nitric oxide (NO) generation in the vascular endothelium. Endothelial dysfunction is characterized by reduced NO production, and is a hallmark of cardiovascular diseases. Drugs with cardiovascular action may activate NOS3 and result in NO release and vasodilation. Moreover, genetic variations affect NOS3 expression and activity, and may partially explain the variability in the responses to cardiovascular drugs. We reviewed NO signaling and genetic effects on NO formation, and the effects of NOS3 polymorphisms, haplotypes and gene-gene interactions within NO signaling pathways on the responses to cardiovascular drugs. We discuss the role of rare NOS3 variants and further gene-gene interactions analysis for the development of novel therapies for cardiovascular diseases.

Interactions Between ABCB1 Genotype and Preoperative Statin Use Impact Clinical Outcomes Among Breast Cancer Patients

Multiple clinical trials investigate statins' effects in breast cancer. The ABCB1 genotype appears to influence statin response and toxicity in the cardiovascular setting. This exploratory study aimed to investigate the interplay between preoperative statin use, ABCB1 genotype, and tumor-specific expression of the statin target 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) in breast cancer. Preoperative statin use, ABCB1 C3435T genotype, and HMGCR expression in relation to outcome were analyzed in 985 primary breast cancer patients from a population-based prospective cohort in Sweden from 2002 to 2012. Preoperative statin use (n = 80) was not associated with ABCB1 C3435T genotype (n = 576), HMGCR expression (n = 848), or clinical outcomes. ABCB1 C3435T TT-carriers had lower risk of breast cancer events than any C-carriers (adjusted hazard ratio (HR_adj) 0.74; 95%CI 0.49, 1.12), but only in non-statin users (P_interaction = 0.042). Statin users with TT genotype had higher risk of distant metastasis (HR_adj 4.37; 95%CI 1.20, 15.91; P_interaction = 0.009) and shorter overall survival than other patients (HR_adj 3.77; 95%CI 1.37, 10.39; P_interaction = 0.019). In conclusion, there were nominally significant interactions between ABCB1 genotype and preoperative statin use on clinical outcomes, while preoperative statin use was not associated with outcomes. Since this is an exploratory study of the impact of the ABCB1 genotype in relation to statin use and clinical outcomes in the breast cancer setting, the results should be interpreted with caution and warrant replication in an independent cohort, preferably in a randomized setting. Since statin use is common in breast cancer patients, it would be of interest to further elucidate the clinical impact of the ABCB1 genotype in breast cancer.

Seventeen years of statin pharmacogenetics: a systematic review

AIM

We evaluated the evidence of pharmacogenetic associations with statins in a systematic review.

METHODS

Two separate outcomes were considered of interest: modification of low-density lipoprotein cholesterol (LDL-C) response and modification of risk for cardiovascular events.

RESULTS

In candidate gene studies, 141 loci were claimed to be associated with LDL-C response. Only 5% of these associations were positively replicated. In addition, six genome-wide association studies of LDL-C response identified common SNPs in APOE, LPA, SLCO1B1, SORT1 and ABCG2 at genome-wide significance. None of the investigated SNPs consistently affected the risk reduction for cardiovascular events.

CONCLUSION

Only five genetic loci were consistently associated with LDL-C response. However, as effect sizes are modest, there is no evidence for the value of genetic testing in clinical practice.

Possible association of ABCB1:c.3435T>C polymorphism with high-density-lipoprotein-cholesterol response to statin treatment--a pilot study

The gene product ABCB1 (formerly MDR1 or P-glycoprotein) is hypothesized to be involved in cholesterol cellular trafficking, redistribution and intestinal re-absorption. Carriers of the ABCB1:3435T allele have previously been associated with decreases in ABCB1 mRNA and protein concentrations and have been correlated with changes in serum lipid concentrations. The aim of this study was to investigate possible association between the ABCB1:3435T>C polymorphism and changes in lipids in patients following statin treatment. Outpatients (n=130) were examined: 43 men (33%), 87 women (67%): treated with atorvastatin or simvastatin (all patients with equivalent dose of 20 or 40 mg/d simvastatin). Blood was taken for ABCB1:3435T>C genotyping, and before and after statin treatment for lipid concentration determination (total cholesterol, high-density-lipoprotein-cholesterol (HDL-C), triglycerides). Change (Δ) in lipid parameters, calculated as differences between measurements before and after treatment, were analyzed with multiple regression adjustments: gender, diabetes, age, body mass index, equivalent statin dose, length of treatment. Univariate and multivariate analyses showed significant differences in ΔHDL-C (univariate p=0.029; multivariate p=0.036) and %ΔHDL-C (univariate p=0.021; multivariate p=0.023) between patients with TT (-0.05 ± 0.13 g/l; -6.8% ± 20%; respectively) and CC+CT genotypes (0.004 ± 0.15 g/l; 4.1 ± 26%; respectively). Reduction of HDL-C in homozygous ABCB1:3435TT patients suggests this genotype could be associated with a reduction in the benefits of statin treatment.

The role of Multidrug Resistance-1 (MDR1) variants in response to atorvastatin among Jordanians

The MDR1 gene encodes for P-glycoprotein (P-gp), which is an efflux transporter at the cell membrane. The P-gp has wide substrate specificity for multiple medications including the lipid lowering drug, atorvastatin. In this study, we investigated the possible association between three common MDR1 gene polymorphisms (G2677T, C3435T, and C1236T), and the lipid lowering effect of atorvastatin among Jordanians. Lipid and lipoproteins were measured in blood samples collected from patients (n = 201) at baseline and during atorvastatin treatment. MDR1 polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism. Both the TT genotype of G2677T and the TT genotype of the C3435T polymorphisms were associated with lower levels of low-density lipoproteins after atorvastatin treatment. However, the effects of atorvastatin on the levels of total cholesterol, triglycerides, and high-density lipoprotein, were not correlated with any of the genotypes in both polymorphisms. Finally, the C1236T polymorphism was not associated with the lipid lowering effect of atorvastatin. In conclusion, the MDR1 gene polymorphisms G2677T, and C3435T, but not C1236T were associated with the lipid lowering effect of atorvastatin among Jordanians.

Genotype variability and haplotype frequency of MDR1 (ABCB1) gene polymorphism in Morocco

The multidrug resistance gene (MDR1) plays an important role in the transport of a wide range of drugs and elimination of xenobiotics from the body. Identification of polymorphisms and haplotypes in the MDR1 gene might not only help understand pharmacokinetics and pharmacodynamics of drugs, but also can help in the prediction of drug responses, toxicity, and side effects, especially, in the era of personalized medicine. We have analyzed the genotypic and haplotypic frequencies of the three most common single-nucleotide polymorphisms in the MDR1 gene in a sample of 100 unrelated healthy Moroccan subjects by polymerase chain reaction-restrictive fragment length polymorphism. The observed genotype frequencies were 43% for 1236CC, 49% for 1236CT, and 8% for 1236TT in exon 12; 49% for 2677GG, 47% for 2677GT, and 4% for 2677TT in exon 21; 39% for 3435CC, 51% 3435CT for 3435TT, and 10% for 3435TT in exon 26, respectively. We found that all polymorphisms were in Hardy-Weinberg equilibrium. Moderate linkage disequilibrium (LD) was observed between the three polymorphisms, the strongest LD in our study has been observed between C1236T and G2677T (D'=0.76; r(2)=0.45). We identified eight haplotypes, the most frequent were 1236C-2677G-3435C (53%), 1236T-2677T-3435T (21%), and 1236C-2677G-3435T (10%), respectively. Our findings might facilitate future studies on pharmacokinetics of P-glycoprotein substrate drugs and interindividual variability to drugs in Moroccan patients.

Cerebrovascular disease in South Asia - Part II: Risk factors and prevention

In South Asian countries, conventional vascular risk factors like hypertension, diabetes mellitus, cardiac disease, smoking, obesity, atrial fibrillation are the dominant ones, while other aetiologies like rheumatic heart disease, infective meningitis-related infarcts and postpartum cerebral venous thrombosis also constitute a big fraction. This review discusses the evidence of prevalence of various risk factors in South Asian countries and possible measures to combat the rising burden of cerebrovascular disease. The last part of the review discusses prevention and identification of risk factors that are unique to or especially found in patient population of South Asia.