APOE polymorphism and carotid atherosclerosis in Korean population: the Dong-gu Study and the Namwon Study

Apolipoprotein E-ε2 and Resistance to Atherosclerosis in Midlife: The PESA Observational Study

BACKGROUND

APOE is a known genetic contributor to cardiovascular disease, but the differential role APOE alleles play in subclinical atherosclerosis remains unclear.

METHODS

The PESA (Progression of Early Subclinical Atherosclerosis) is an observational cohort study that recruited 4184 middle-aged asymptomatic individuals to be screened for cardiovascular risk and multiterritorial subclinical atherosclerosis. Participants were APOE-genotyped, and omics data were additionally evaluated.

RESULTS

In the PESA study, the frequencies for APOE -ε2, -ε3, and -ε4 alleles were 0.060, 0.844, and 0.096, respectively. This study included a subcohort of 3887 participants (45.8±4.3 years of age; 62% males). As expected, APOE-ε4 carriers were at the highest risk for cardiovascular disease and had significantly greater odds of having subclinical atherosclerosis compared with ε3/ε3 carriers, which was mainly explained by their higher levels of low-density lipoprotein (LDL)-cholesterol. In turn, APOE-ε2 carriers were at the lowest risk for cardiovascular disease and had significantly lower odds of having subclinical atherosclerosis in several vascular territories (carotids: 0.62 [95% CI, 0.47-0.81]; P=0.00043; femorals: 0.60 [0.47-0.78]; P=9.96×10-5; coronaries: 0.53 [0.39-0.74]; P=0.00013; and increased PESA score: 0.58 [0.48-0.71]; P=3.16×10-8). This APOE-ε2 atheroprotective effect was mostly independent of the associated lower LDL-cholesterol levels and other cardiovascular risk factors. The protection conferred by the ε2 allele was greater with age (50-54 years: 0.49 [95% CI, 0.32-0.73]; P=0.00045), and normal (<150 mg/dL) levels of triglycerides (0.54 [0.44-0.66]; P=4.70×10-9 versus 0.90 [0.57-1.43]; P=0.67 if ≥150 mg/dL). Omics analysis revealed an enrichment of several canonical pathways associated with anti-inflammatory mechanisms together with the modulation of erythrocyte homeostasis, coagulation, and complement activation in ε2 carriers that might play a relevant role in the ε2's atheroprotective effect.

CONCLUSIONS

This work sheds light on the role of APOE in cardiovascular disease development with important therapeutic and prevention implications on cardiovascular health, especially in early midlife.

REGISTRATION

URL: https://www.clinicaltrials.gov: NCT01410318.

Extracranial carotid artery atherosclerotic plaque and APOE polymorphisms: a systematic review and meta-analysis

Introduction

Carotid atherosclerotic plaque is an important independent risk factor for stroke. Apolipoprotein E (APOE) influences cholesterol levels and certain isoforms are associated with increased carotid atherosclerosis, though the exact association between APOE and carotid plaque is uncertain. The study aimed to evaluate the association between APOE and carotid plaque.

Methods

A systematic review was performed to retrieve all studies which examined the association between carotid plaque and APOE. This study was conducted in accordance with the PRISMA guidelines. Independent readers extracted the relevant data from each study including the type of imaging assessment, plaque definition, frequency of APOE E4 carrier status and type of genotyping. Meta-analyses with an assessment of study heterogeneity and publication bias were performed. Results were presented in a forest plot and summarized using a random-effects model.

Results

After screening 838 studies, 17 studies were included for systematic review. A meta-analysis of 5 published studies showed a significant association between ε4 homozygosity and carotid plaque [odds ratio (OR), 1.53; 95% CI, 1.16, 2.02; p = .003]. Additionally, there was a significant association between patients possessing at least one ε4 allele, heterozygotes or homozygotes, and carotid plaque (OR, 1.25; 95% CI, 1.03, 1.52; p = .03). Lastly, there was no association between ε4 heterozygosity and carotid plaque (OR, 1.08; 95% CI, 0.93, 1.26; p = .30).

Conclusion

APOE ε4 allele is significantly associated with extracranial carotid atherosclerotic plaque, especially for homozygous individuals.

Apolipoprotein E ε2 allele is associated with lower risk of carotid artery obstruction in a population-based autopsy study

INTRODUCTION

Apolipoprotein E (APOE) ε4 allele has been associated with higher carotid atherosclerosis risk, while the APOE-ε2 seems to decrease this risk. Data from autopsy studies, where carotid arteries can be evaluated in their full extension, is scarce. Therefore, we investigated the association between APOE alleles and direct morphometric measurements of carotid atherosclerosis in an autopsy study with an admixed sample.

METHODS

We measured the intima-media thickness (IMT) and stenosis of the common (CCA) and internal carotid (ICA) arteries. The APOE polymorphisms were determined by real-time polymerase chain reaction. Participants were classified into three groups according to the APOE alleles (ε2, ε3, and ε4). We evaluated the association between APOE groups and carotid atherosclerosis using adjusted regression models and included interaction terms of APOE alleles with age, sex, and race.

RESULTS

We evaluated 1,850 carotid artery samples from 185 participants (mean age=75±12 years old, 55% female, and 71% White). The APOE-ε2 group (n=17) had a lower carotid obstruction and a lower number of severe stenoses (≥ 70%). Having at least one ε4 allele (n=51) was not associated with carotid atherosclerosis. APOE alleles were also not associated with carotid IMT. Age, sex, and race did not modify these relationships.

CONCLUSION

APOE-ε2 carriers had a lower percentage of carotid obstruction and less severe stenosis. APOE-ε4 was not related to a higher risk of carotid atherosclerosis in this cross-sectional population-based autopsy study.

Involvement of APOE in Incidence of Revascularization in Patients Affected by Peripheral Arterial Disease: A Prospective Study from Southern Italy

INTRODUCTION

Atherosclerosis is a complex multifactorial disease and apolipoprotein E (APOE) polymorphism has been associated with cardiovascular events. The APOE gene, located on chromosome 19q13.2, has an important role in lipid metabolism, in particular on circulating cholesterol levels, implying further pleiotropic effects; from its polymorphism are derived three alleles (ε2, ε3 and ε4), which induce different phenotypes, while its impact on carotid and femoral atherosclerosis is still controversial.

OBJECTIVES

The aim of the study is to investigate the relationship between APOE genotypes and peripheral revascularization in a cohort of patients affected by advanced peripheral arterial disease (PAD) at a prolonged follow-up.

MATERIALS AND METHODS

Some 332 patients (259 males and 73 females; mean age 70.86 ± 7.95 years) with severe PAD were enrolled in a longitudinal study, with a 90.75 ± 32.25 month follow-up, assessing major adverse cardiovascular events (MACE).

RESULTS

As compared with ε3/ε3, in ε4 patients we observed a significant higher incidence of carotid (13.2% vs. 5.6%; HR = 2.485, 95% CI 1.062-5.814; p = 0.036) and lower limb (11.8% vs. 4.3%; HR = 2.765, 95% CI 1.091-7.008; p = 0.032) revascularizations and, accordingly, a higher incidence of total peripheral revascularizations (13.5% vs. 9.5%; HR = 2.705, 95% CI 1.420-5.151; p = 0.002). HR remained statistically significant even when adjusted for classic cardiovascular risk factors.

CONCLUSIONS

In our observational study, we confirm that the ε4 allele is associated with higher total peripheral revascularization in patients with advanced atherosclerotic vascular disease at prolonged follow-up.

Association of CELSR2, APOB100, ABCG5/8, LDLR, and APOE polymorphisms and their genetic risks with lipids among the Thai subjects

Background

Hypercholesterolemia is a common cardiovascular risk factor. The aim of this study was to investigate the association of CELSR2 (rs629301), APOB100 (rs1367117), ABCG5/8 (rs6544713), LDLR (rs6511720), and APOE (rs429358, rs7412) polymorphisms, and their genetic risk scores with lipids among Thai subjects.

Methods

A total of 459 study subjects (184 males, and 275 females) were enrolled. Blood pressure, serum lipids, and fasting blood sugar were measured. CELSR2 (rs629301), APOB100 (rs1367117), ABCG5/8 (rs6544713), and LDLR (rs6511720) polymorphisms were analyzed using PCR-HRM. APOE (rs429358, rs7412) polymorphism was analyzed using PCR-RFLP.

Results

Total cholesterol (TC) levels were significantly higher in APOB100 AA genotype compared with GG, or AA + AG genotypes in total subjects. In addition, significantly higher concentrations of TC and low density lipoprotein cholesterol (LDL-C) were observed in APOE4 carriers compared to APOE2 carriers in total subjects, males, and females. The significantly higher concentrations of TC were observed in APOE4 carriers compared to APOE3 carriers in females. Moreover, the concentrations of TC, and LDL-C were significantly increased with genetic risk scores of APOB100, and APOE polymorphisms in total subjects, and females. There was no association between CELSR2 (rs629301), ABCG5/8 (rs6544713), and LDLR (rs6511720) polymorphisms and serum lipids.

Conclusion

APOB100 (rs1367117), and APOE (rs429358, rs7412) but not CELSR2 (rs629301), ABCG5/8 (rs6544713), and LDLR (rs6511720) polymorphisms were associated with serum lipids. The cumulative risk alleles of APOB100 (rs1367117), and APOE (rs429358, rs7412) polymorphisms could enhance the elevated concentrations of TC, and LDL-C, and they may be used to predict severity of hypercholesterolemia among Thai subjects.

Apolipoprotein E genotypes were not associated with intracranial atherosclerosis: a population-based autopsy study

BACKGROUND

Apolipoprotein E gene (APOE) ε4 allele is associated with a higher risk of carotid atherosclerosis, but less is known about the association of APOE with intracranial atherosclerotic disease (IAD). We aimed to investigate the association of APOE alleles with IAD in a cross-sectional autopsy study.

METHODS

We measured the stenosis in the 12 arteries of the Circle of Willis using postmortem morphometric measurements. The APOE polymorphism was determined by real-time polymerase chain reaction. We assessed the association between APOE polymorphism and IAD using regression models adjusted for sociodemographic and clinical variables. We also verified the modifier effect of age, sex, and race on this association. We stratified the analysis by age group to investigate the possibility of attrition bias.

RESULTS

In 400 participants (mean age=73.2±12.3 years old, 51% female, and 64% White), IAD was evaluated in 4,504 artery segments. APOE-ε4 was not associated with IAD nor with the number of artery stenosis compared to non-APOE-ε4 carriers. Sociodemographic variables did not modify this relationship. Among participants older than 70 years, there was a trend towards an association between APOE allele ε4 and a lower stenosis index in the middle cerebral artery, suggesting attrition bias related to the APOE-ε4 effect on mortality.

CONCLUSIONS

APOE alleles were not associated with IAD in this population-based autopsy study. Lower stenosis in older participants suggests the possibility of attrition bias.

Effect of Apolipoprotein E ε4 Allele on the Progression of Carotid Atherosclerosis Through Apolipoprotein Levels

Background

Patients and methods

Results

Conclusion

The Association between the Apolipoprotein E Gene Polymorphism and All-cause Mortality in the Korean Population

BACKGROUND

Apolipoprotein E (APOE) gene polymorphism is associated with neurodegenerative and cardiovascular diseases. Although the effects of the gene differ by ethnic group, few studies have examined Asians. Therefore, the association between APOE polymorphism and mortality in Koreans was evaluated in this study.

METHODS

This study population included participants from the Dong-gu and Namwon Studies. APOE genotypes were categorized as E2 (E2/E2 and E2/E3), E3 (E3/E3), and E4 (E3/E4 and E4/E4). Multivariate Cox proportional hazard models were constructed using the E3 allele as a reference.

RESULTS

In the model adjusting for study site, age, gender, and lifestyle, the hazard ratio (HR) of mortality for those with the E4 allele was 1.08 (95% confidence interval [CI], 0.97-1.20), while that for those with the E2 allele was 0.84 (95% CI, 0.74-0.96). After adjusting for blood lipids to evaluate their mediating effects, the HRs of mortality for those with E4 and E2 alleles were 1.08 (95% CI, 0.97-1.20) and 0.80 (95% CI, 0.70-0.92), respectively. These associations were more evident in younger groups, with HRs of 0.70 (95% CI, 0.52-0.92) for the E2 allele and 1.25 (95% CI, 1.03-1.53) for the E4 allele.

CONCLUSION

In two large population-based cohort studies, the E2 allele was associated with a lower risk of mortality compared with the E3 allele, whereas the E4 genotype was not associated with mortality in Koreans.

Genetic susceptibility to cerebrovascular disease: A systematic review

Investigation of genetic susceptibility to cerebrovascular disease has been of growing interest. A systematic review of human studies assessing neurogenomic aspects of cerebrovascular disease was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. Any association study exploring genetic variants located in the exome associated with one of the major cerebrovascular diseases with at least 500 subjects was eligible for inclusion. Of 6874 manuscripts identified, 35 studies met the inclusion criteria. Most studies of interest focused on ischemic stroke and cerebrovascular occlusive disease. Large cohort genetic association studies on hemorrhagic cerebrovascular disease were less common. In addition to rare, well-established monogenic conditions with significant risk for cerebrovascular disease, a number of genetic variants are also relevant to cerebrovascular pathogenesis as part of a multifactorial process. The 45 polymorphisms identified were located in genes involved in processes related to endothelial and vascular health (15 (33.4%) variants), plasma lipid metabolism (10 (22.2%) variants), inflammation (9 (20%) variants), coagulation (3 (6.7%) variants), and blood pressure modulation (2 (4.4%) variants), and other (6 (13.3%) variants). This work represents a comprehensive overview of genetic variants in the exome relevant to ischemic and hemorrhagic stroke pathophysiology.

Apolipoprotein E polymorphisms are associated with ischemic stroke susceptibility in a Northwest China Han population

Ischemic stroke (IS), the leading neurology cause of death and disability worldwide, is influenced by gene polymorphisms. To explore the association between IS and Apolipoprotein E (APOE) gene polymorphisms, a case–control study containing 513 IS patients and 514 controls without IS was conducted in a Northwest China Han population. MassARRAY iPLEX system was applied to determine the APOE polymorphisms according to the alleles of two single nucleotide polymorphisms (SNPs) of APOE, rs429358, and rs7412. The results showed that rs429358 and rs7412 were in Hardy–Weinberg equilibrium (HWE) in both cases and controls groups. APOE ε4 allele, ε4/ε4 genotype, and ε4-containing genotypes were associated with IS. According to the results of Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification system, APOE ε2 allele, ε4 allele, and ε4/ε4 genotype were associated with large artery atherosclerosis IS subtypes. In addition, the results also indicated that the ε4 allele related to undetermined IS and ε4/ε4 genotype was related to small vessel disease IS. Compared with subjects with non-ε4-containing genotypes, the total cholesterol (TC) and low-density lipoprotein (LDL) level in blood and the proportion of cardiopath history were higher in all subjects with ε4-containing genotypes. Besides, the triacylglycerides (TG) level in blood was higher in controls with ε4-containing genotypes. In conclusion, in a Northwest China Han population, APOE ε4 allele was associated with blood lipid level. The TC and LDL levels were the independent risk factors for IS. APOE was a risk gene for IS, but not independent, especially for large artery atherosclerosis IS.

Association of APOE Genotype with Bone Mineral Density in Men and Women: The Dong-gu and Namwon Studies

Many studies have investigated relationships between APOE genotype and bone mineral density (BMD). However, the results of these studies have been inconsistent. Few studies have been carried out in Asian populations. We studied the relationship of the APOE gene polymorphism and BMD in two large population-based studies. The datasets included the Dong-gu Study (3575 men and 5335 women) and the Namwon Study (2310 men, 3512 women). Lumbar spine and femoral neck BMD were measured by dual-energy X-ray absorptiometry. APOE genotypes were analyzed by polymerase chain reaction–restriction fragment length polymorphism. The APOE genotypes were classified into APOE E2 (E2/E2 and E2/E3), APOE E3 (E3/E3), and APOE E4 (E3/E4 and E4/E4). The genotype distribution of the study population was in Hardy-Weinberg equilibrium. There were no significant differences among APOE genotype groups in lumbar and femoral neck BMD in either cohort. Our data do not support the hypothesis that the APOE genotype is associated with BMD.

APOE Polymorphism Is Associated with C-reactive Protein Levels but Not with White Blood Cell Count: Dong-gu Study and Namwon Study

We evaluated the association of the APOE polymorphism with serum C-reactive protein levels and white blood cell count in two large population-based studies in Korean. The datasets included the Dong-gu study (n = 8,893) and the Namwon Study (n = 10,032). APOE genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism. Multivariable linear regression analysis was performed to evaluate the relationship of APOE genotypes with C-reactive protein levels and white blood cell count with adjustments for age, sex, body mass index, smoking, diabetes, hypertension, and serum lipids. In the multivariate model, carriers of E3E4 or E4E4 genotype had significantly lower C-reactive protein levels compared with carriers of E3E3 genotype group (0.50 mg/L vs. 0.67 mg/L; 0.37 mg/L vs. 0.67 mg/L, respectively, for the Dong-gu Study and 0.47 mg/L vs. 0.66 mg/L; 0.45 mg/L vs. 0.66 mg/L, respectively, for the Namwon Study). However, there was no difference in white blood cell count among APOE genotypes. We found that the APOE E4 allele is associated with lower C-reactive protein levels, but not white blood cell count. Our results suggest that APOE genotype may influence C-reactive protein levels through non-inflammatory pathway.

Meta-analysis of apolipoprotein E gene polymorphism and susceptibility of myocardial infarction

A number of case-control studies have been conducted to clarify the association between ApoE polymorphisms and myocardial infarction (MI); however, the results are inconsistent. This meta-analysis was performed to clarify this issue using all the available evidence. Searching in PubMed retrieved all eligible articles. A total of 33 studies were included in this meta-analysis, including 18752 MI cases and 18963 controls. The pooled analysis based on all included studies showed that the MI patients had a decreased frequency of the ε2 allele (OR = 0.78, 95% CI = 0.70–0.87) and an increased frequency of the ε4 allele (OR = 1.15, 95% CI = 1.10–1.20); The results also showed a decreased susceptibility of MI in the ε2ε3 vs. ε3ε3 analysis (OR = 0.79, 95% CI = 0.68–0.90) and in the ε2 vs. ε3 analysis (OR = 0.78, 95% CI = 0.69–0.89), an increased susceptibility of MI in the ε3ε4 vs. ε3ε3 analysis (OR = 1.26, 95% CI = 1.12–1.41), in the ε4 vs. ε3 analysis (OR = 1.22, 95% CI = 1.12–1.32) and in the ε4ε4 vs. ε3ε3 analysis (OR = 1.59, 95% CI = 1.15–2.19). However, there were no significant associations among polymorphisms and MI for the following genetic models: frequency of the ε3 allele (OR = 0.99, 95% CI = 0.96–1.02); ε2ε2 vs. ε3ε3 analysis (OR = 0.73, 95% CI = 0.40–1.32); or ε2ε4 vs. ε3ε3 analysis (OR = 1.10, 95% CI = 0.99–1.21). Our results suggested that the ε4 allele of ApoE is a risk factor for the development of MI and the ε2 allele of ApoE is a protective factor in the development of MI.