Association between apolipoprotein E polymorphism, lipids, and coronary artery disease in Tunisian type 2 diabetes

Relationships of apolipoprotein E genotypes with a cluster of seven in persons with type 2 diabetes

OBJECTIVE.

The objective of the study was to determine if there would be statistically significant differences or trends among apolipoprotein E genotypes (2/2, 2/3, 2/4, 3/3, 3/4, and 4/4) for each member of the cluster of seven associated with type 2 diabetes (T2D). The cluster of seven includes abdominal obesity, hypertension, platelet hyperaggregability, hyperglycemia, dyslipidemia (decreased plasma levels of high-density lipoprotein cholesterol (HDL-C) and increased plasma levels of triglycerides)), increased low-density lipoprotein (LDL) oxidation, and increased inflammation.

METHODS.

Forty-six patients with well-controlled T2D participated in the study. Abdominal obesity (assessed by waist circumference), hypertension (measured by manual sphygmomanometry), platelet hyperaggregability (measured by bleeding time), hyperglycemia (by enzymatic kit and spectrophotometry), decreased plasma levels of HDL-C and increased plasma levels of triglycerides (by enzymatic kit and spectrophotometry), increased LDL oxidation (measured by LDL conjugated dienes using spectrophotometry) and increased inflammation measured by C-reactive protein (CRP) (by EIA kit) were determined.

RESULTS.

All genotypes, except 2/2 were found in the population studied. Abdominal obesity did not vary significantly across the five genotypes. However, glucose levels trended progressively higher going from 2/3 to 2/4 to 3/4 to 4/4. Systolic blood pressure was higher in 3/4 compared to 2/4 and trended higher in 3/4 compared to 3/3. Diastolic blood pressure trended higher in 3/3 vs 2/4 and significantly higher in 3/4 compared to 2/4. Triglycerides trended higher in 3/4 vs 3/3 while HDL-C came close to trending downward in 4/4 compared to 2/4. Bleeding time was unaffected by genotype. Plasma LDL conjugated dienes trended higher in 3/4 vs 2/4 and were significantly higher in 3/4 vs 3/3. CRP trended higher in 4/4 vs 2/3.

CONCLUSION.

We can conclude that those with at least one 4 allele in the presence of another allele being 2, 3 or 4 is potentially (in the case of trends) deleterious or is deleterious in terms of hyperglycemia, hypertension (systolic and diastolic blood pressure), dyslipidemia, LDL conjugated dienes and CRP levels.

Sex Differences in Cognition Across Aging

Sex and gender differences are seen in cognitive disturbances in a variety of neurological and psychiatry diseases. Men are more likely to have cognitive symptoms in schizophrenia whereas women are more likely to have more severe cognitive symptoms with major depressive disorder and Alzheimer's disease. Thus, it is important to understand sex and gender differences in underlying cognitive abilities with and without disease. Sex differences are noted in performance across various cognitive domains - with males typically outperforming females in spatial tasks and females typically outperforming males in verbal tasks. Furthermore, there are striking sex differences in brain networks that are activated during cognitive tasks and in learning strategies. Although rarely studied, there are also sex differences in the trajectory of cognitive aging. It is important to pay attention to these sex differences as they inform researchers of potential differences in resilience to age-related cognitive decline and underlying mechanisms for both healthy and pathological cognitive aging, depending on sex. We review literature on the progressive neurodegenerative disorder, Alzheimer's disease, as an example of pathological cognitive aging in which human females show greater lifetime risk, neuropathology, and cognitive impairment, compared to human males. Not surprisingly, the relationships between sex and cognition, cognitive aging, and Alzheimer's disease are nuanced and multifaceted. As such, this chapter will end with a discussion of lifestyle factors, like education and diet, as modifiable factors that can alter cognitive aging by sex. Understanding how cognition changes across age and contributing factors, like sex differences, will be essential to improving care for older adults.

Identification of Potential Targets Linked to the Cardiovascular/Alzheimer’s Axis through Bioinformatics Approaches

The identification of common targets in Alzheimer’s disease (AD) and cardiovascular disease (CVD) in recent years makes the study of the CVD/AD axis a research topic of great interest. Besides aging, other links between CVD and AD have been described, suggesting the existence of common molecular mechanisms. Our study aimed to identify common targets in the CVD/AD axis. For this purpose, genomic data from calcified and healthy femoral artery samples were used to identify differentially expressed genes (DEGs), which were used to generate a protein–protein interaction network, where a module related to AD was identified. This module was enriched with the functionally closest proteins and analyzed using different centrality algorithms to determine the main targets in the CVD/AD axis. Validation was performed by proteomic and data mining analyses. The proteins identified with an important role in both pathologies were apolipoprotein E and haptoglobin as DEGs, with a fold change about +2 and −2, in calcified femoral artery vs healthy artery, respectively, and clusterin and alpha-2-macroglobulin as close interactors that matched in our proteomic analysis. However, further studies are needed to elucidate the specific role of these proteins, and to evaluate its function as biomarkers or therapeutic targets.

Dissecting the Association of Apolipoprotein E Gene Polymorphisms With Type 2 Diabetes Mellitus and Coronary Artery Disease

BACKGROUND

Apolipoprotein E (APOE) gene mediates lipoprotein clearance and is one of the most studied candidate genes for type 2 diabetes mellitus (T2DM) and coronary artery disease (CAD). This study was performed to determine the association between APOE polymorphisms and T2DM with and without CAD, and its effect on plasma lipid levels in a Chinese population.

METHODS

A total of 1,414 subjects involving 869 patients and 545 health individuals were recruited. These patients were categorized into three distinct groups: 264 in T2DM group, 401 in CAD group, and 204 in T2DM+CAD group. Logistic regression analysis was used to obtain odds ratio (OR) and 95% confidence interval (CI) in predicting the risk probability of APOE. Besides, a meta-analysis was preformed to integrate an evaluation index to evaluate their associations.

RESULTS

Genotype frequency ratio of genotype ϵ3/4 and allele ϵ4 among the CAD patients with or without T2DM was obviously increased. Compared with ϵ3/3 genotype, the ϵ3/4 genotype had a significant increased risk of CAD (adjusted OR = 1.90, 95% CI = 1.30-2.77) and T2DM+CAD (adjusted OR = 1.95, 95% CI = 1.24-3.08). In the meta-analysis, four studies were included and provided a strong evidence for the APOE ϵ4 mutation elevating the risk of CAD in patients with T2DM (ϵ3/ϵ4+ϵ4/ϵ4 vs. ϵ3/ϵ3, OR = 1.51, 95% CI = 1.13-2.02). In the T2DM group, the plasma levels of low-density lipoprotein cholesterol (LDL-C) showed significant difference among the three APOE isoforms. The high-density lipoprotein cholesterol (HDL-C) levels of CAD patients with ϵ4-bearing genotypes were lower than those with ϵ3/3 genotype.

CONCLUSIONS

Our results indicate that APOE gene polymorphisms are related to CAD with or without T2DM and have influence on lipid profiles in both T2DM and CAD patients.

Apolipoprotein E gene polymorphism and the risk of cardiovascular disease and type 2 diabetes

BACKGROUND

The role of apolipoprotein E gene (APOE) in lipid metabolism has been well established, and APOE is associated with the risk of cardiovascular disease (CVD) and diabetes mellitus (DM). However, the relationship between APOE polymorphisms and type 2 diabetes (T2DM) with or without CVD remains unclear.

METHODS

In this cross-sectional study, a total of 924 participants including 211 controls (CVD-T2DM-), 247 T2DM patients with CVD (CVD-T2DM+), 232 CVD patients without T2DM (CVD + T2DM-) and 234 T2DM patients with CVD (CVD + T2DM+), were genotyped using chip platform. The association between APOE polymorphisms and T2DM patients with or without CVD was analyzed by univariable and multivariable logistic analysis.

RESULTS

The present study showed that the frequency of E3/E4 increased in T2DM patients with CVD (p < 0.01). The ε4 allele was higher in CVD patients without T2DM (p < 0.01) and T2DM patients with CVD (p < 0.01) as compared with the controls.

CONCLUSIONS

The subjects carrying ε4 allele have increased risk of CVD and T2DM, and exhibit higher level of lipid profiles.

Association of APOE and CETP TaqIB Polymorphisms with Type 2 Diabetes Mellitus

Apolipoprotein E (APOE) and cholesteryl ester transfer protein (CETP) play an important role in the lipid metabolism. Dyslipidemia is one of the complications that found in type 2 diabetes mellitus (T2DM) patients. The aim of this study was to investigate the association of APOE and CETP TaqIB polymorphisms with T2DM and its related metabolic parameters in Southern Thai population. Study subjects were 241 T2DM patients and 275 healthy controls. The APOE and CETP TaqIB polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. APOE polymorphism showed a statistical difference in allele frequencies (p = 0.025) and genotype distributions (p <0.001) between T2DM patients and healthy controls. The E4 carriers were associated with a significantly higher TC, and/or LDL-C levels compared to the E2 and E3 carriers, respectively in all subjects and healthy controls. Moreover, CETP TaqIB B2B2 genotype was significantly higher HDL-C levels compared with B1B1, and B1B2 genotypes in all subjects, and T2DM patients. Multiple logistic regression analysis showed that APOE and CETP TaqIB polymorphisms were not associated with T2DM. In conclusion, APOE and CETP TaqIB polymorphisms might not be the genetic risk factors for T2DM in Southern Thai population, however, APOE and CETP TaqIB polymorphisms were associated with serum lipids in healthy controls and T2DM, respectively.

The Associations between Apolipoprotein E Gene Epsilon2/Epsilon3/Epsilon4 Polymorphisms and the Risk of Coronary Artery Disease in Patients with Type 2 Diabetes Mellitus

Background and Objective: Apolipoprotein E (APOE) plays important roles in lipoprotein metabolism and cardiovascular disease. Evidence suggests the APOE gene epsilon2/epsilon3/epsilon4 (ε2/ε3/ε4) polymorphisms might be associated with the susceptibility of coronary artery disease (CAD) in patients with type 2 diabetes mellitus (T2DM). However, no clear consensus has yet been established. Therefore, the aim of this meta-analysis is to provide a precise conclusion on the potential association between APOE ε2/ε3/ε4 polymorphisms and the risk of CAD in patients with T2DM based on case-control studies.

Methods: Pubmed, Embase, Chinese National Knowledge Infrastructure (CNKI), and Wanfang databases were searched for all relevant studies prior to August 2017 in English and Chinese language. The pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were used to assess the strength of the relationships. The between-study heterogeneity was evaluated by Cochran's Q-test and the I² index to adopt fixed- or random- effect models.

Results: A total of 13 studies were eligible for inclusion. There was evidence for significant associations between APOE ε4 mutation and the risk of CAD in patients with T2DM (for ε3/ε4 vs. ε3/ε3: OR = 1.69, 95% CI = 1.38–2.08, P < 0.001; for ε4/ε4 vs. ε3/ε3: OR = 2.72, 95% CI = 1.61–4.60, P < 0.001; for ε4/ε4+ε3/ε4 vs. ε3/ε3: OR = 1.83, 95% CI = 1.52–2.22, P < 0.001; for ε4 allele vs. ε3 allele: OR = 1.64, 95% CI = 1.40–1.94, P < 0.001). In contrast, no significant associations were found in genetic model of APOE ε2 mutation (for ε2/ε2 vs. ε3/ε3: OR = 1.67, 95% CI = 0.90–3.09, P = 0.104; for ε2/ε3 vs. ε3/ε3: OR = 1.18, 95% CI = 0.93–1.51, P = 0.175; for ε2/ε2+ε2/ε3 vs. ε3/ε3: OR = 1.26, 95% CI = 0.88–1.82, P = 0.212; for ε2 allele vs. ε3 allele: OR = 1.34, 95% CI = 0.98–1.84, P = 0.07).

Conclusions: The APOE gene ε4 mutation is associated with an increased risk of CAD in patients with T2DM, while the ε2 variation has null association with this disease.

Apolipoprotein E gene polymorphism and risk of type 2 diabetes and cardiovascular disease

BACKGROUND

Lipoprotein-related mechanisms have been associated with damage to the cardiovascular system in diabetic patients. Apolipoprotein E gene which affects the clearance of lipoproteins and consequently the lipid profile in our body is one of the most studied candidate genes and recently has been reported to be associated with T2DM and CAD. In this work, we studied the association of apoE gene polymorphism with T2DM and CVD and its effect on plasma lipids profile.

METHODS

Our study was conducted on 284 subjects categorized into 100 patients with T2DM, 100 patients with T2DM complicated with CVD and 84 normal control subjects. ApoE gene polymorphism was genotyped by real-time PCR using TaqMan(®) SNP Genotyping Assay.

RESULTS

ApoE E3/E3 genotype was the most common in our subjects. The frequencies of E3/E4 genotype and ε4 allele were increased in both T2DM patients and CVD patients as compared with controls, but were significant only in CVD patients (p = 0.004 and 0.007, respectively). Diabetic patients who carried E3/E4 genotype were at 2.4-fold increased risk to develop CVD (95 % CI 1.14-5.19, P = 0.02) and the ε4 allele associated with 2.23-fold higher CVD risk (95 % CI 1.09-4.59, P = 0.02). After adjustment for other established risk factors, E3/E4 genotype was an independent risk factor for CVD (OR = 2.3, p = 0.009) but not for T2DM (OR = 1.7, p = 0.28), while ε4 allele was an independent risk factor for both T2DM (OR = 2.2, p = 0.04) and CVD (OR = 3.0, p = 0.018) with 5.9-fold increased risk to develop CVD in T2DM patients (p = 0.019). E3/E4 genotype associated with significantly higher levels of TC and non HDL-C in all groups and with significantly higher levels of LDL-C in both T2DM and CVD patients.

CONCLUSIONS

ApoE gene polymorphisms associate with CVD and affect the lipid profile. The ε4 allele is an independent risk factor for both T2DM and CVD. Further genetic studies to add information beyond the traditional cardiovascular risk factors in T2DM and to identify risk genotypes will help in early prediction and identification of at risk patients.

Plasma proprotein convertase subtilisin/kexin type 9 is associated with Lp(a) in type 2 diabetic patients

AIM

Recent in vitro researches have shown that plasma Lp(a) can be reduced using a proprotein convertase subtilisin/kexin type 9 (PCSK9)-inhibitory monoclonal antibody. In our clinical study we tried to investigate the association between plasma Lp(a) and PCSK9 in Type 2 diabetic patients with elevated plasma Lp(a), and to check whether such an association would be related to LDL-receptor (LDL-R) levels.

METHODS

Plasma PCSK9 and LDL-R concentrations were measured by sandwich ELISA methods using recombinant human PCSK9 protein and LDL-R protein as standards in a cohort with type 2 diabetic patients (n=50) compared to an age- and sex-matched control group (n=50). Both clinical and biochemical parameters were determined in all patients.

RESULTS

Plasma PCSK9 level was significantly elevated in T2DM patients compared to controls (44.61±14.44 and 33.22±11.79ng/mL, respectively, P<0.0001). However LDL-R levels did not differ between the two groups. Remarkably, plasma PCSK9 levels were positively correlated with Lp(a) levels in whole population (r=+0.227, P=0.03) as well as in T2DM group (r=+0.398, P=0.0061) but not in control group. Multiple linear regression analysis showed that plasma Lp(a) levels were independently associated to those of PCSK9.

CONCLUSION

Lp(a) has been proposed as a contributing factor to the accelerated development of macrovascular complications in T2DM. Its synergic effect with PCSK9 may explain the enhanced atherogenicity in T2DM patients.

Apolipoprotein E gene polymorphism: effects on plasma lipids and risk of type 2 diabetes and coronary artery disease

BACKGROUND

The most common apolipoprotein E (apoE) gene polymorphism has been found to influence plasma lipid concentration and its correlation with coronary artery disease (CAD) has been extensively investigated in the last decade. It is, however, unclear whether apoE gene polymorphism is also associated with increased risk of type 2 diabetes mellitus (T2DM). The knowledge of this study may provide the primary prevention for T2DM and CAD development before its initiation and progression. Therefore, this study was carried out to determine the association between apoE gene polymorphism and T2DM with and without CAD and its role in lipid metabolism.

METHODS

The case-control study was carried out on a total of 451 samples including 149 normal control subjects, 155 subjects with T2DM, and 147 subjects with T2DM complicated with CAD. The apoE gene polymorphism was tested by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Univariable and multivariable logistic regression analyses were used to identify the possible risks of T2DM and CAD.

RESULTS

A significantly increased frequency of E3/E4 genotype was observed only in T2DM with CAD group (p = 0.0004), whereas the ε4 allele was significantly higher in both T2DM (p = 0.047) and T2DM with CAD (p = 0.009) as compared with controls. E3/E4 genotype was also the independent risk in developing CAD after adjusting with established risk factors with adjusted odds ratio (OR) 2.52 (95%CI 1.28-4.97, p = 0.008). The independent predictor of individuals carrying ε4 allele still remained significantly associated with both CAD (adjusted OR 2.32, 95%CI 1.17-4.61, p = 0.016) and T2DM (adjusted OR 2.04, 95%CI 1.07-3.86, p = 0.029). After simultaneously examining the joint association of E3/E4 genotype combined with either obesity or smoking the risk increased to approximately 5-fold in T2DM (adjusted OR 4.93, 95%CI 1.74-13.98, p = 0.003) and 10-fold in CAD (adjusted OR 10.48, 95%CI 3.56-30.79, p < 0.0001). The association between apoE genotypes on plasma lipid levels was compared between E3/E3 as a reference and E4-bearing genotypes. E4-bearing genotypes showed lower HDL-C and higher VLDL-C and TG, whereas other values of plasma lipid concentrations showed no significant difference.

CONCLUSIONS

These results indicate that ε4 allele has influence on lipid profiles and is associated with the development of both T2DM with and without CAD, and furthermore, it increased the risk among the subjects with obesity and/or smoking, the conditions associated with high oxidative stress.