Association of apolipoprotein E gene polymorphism with end-stage renal disease and hyperlipidemia in patients on long-term hemodialysis

BACKGROUND

Cardiovascular diseases (CVDs) are the leading cause of death of patients with chronic renal failure. Apolipoprotein E (apoE) plays an important role in the homeostasis of cholesterol and triglycerides.

OBJECTIVE

We aimed to investigate the possible link(s) between apoE gene polymorphism, inflammation and lipoproteins in hemodialysis patients.

METHODS

We studied 109 end-stage renal disease (ESRD) patients and 97 controls. The serum lipids, apolipoproteins, lipoprotein particles, high-sensitivity C-reactive protein (hs-CRP) and total homocysteine (t-Hcy) levels and paraoxonase (PON) activity were determined in our patients. We also analyzed apoE gene polymorphism in the patients and controls.

RESULTS

The analysis of the apoE gene demonstrated a predominance of the e3 allele in both the patients and controls, followed by the e4 and then the e2 alleles. The analysis of the apoE genotype and allele frequencies showed significantly higher e4 allele and E3E4 genotype frequencies and decreased e3 allele and E3E3 genotype frequencies in the patients compared with the controls. The e2, e4 and E3E4 carriers within the ESRD patient population presented an atherogenic lipid profile. However, there were no significant variations in the serum PON activity and the hs-CRP and t-Hcy levels between individuals with different apoE polymorphisms.

CONCLUSIONS

Our findings suggest an association between the e4 allele, E3E4 genotype and ESRD. The apoE polymorphism affects the serum lipoprotein levels, and the ESRD patients who are e4 and e2 allele carriers are more likely to present an atherogenic lipoprotein profile that may be a major factor associated with increased risk of CVD.

Association of apoE gene expression and its gene polymorphism with nephrotic syndrome susceptibility: a meta-analysis of experimental and human studies

Apolipoprotein E (apoE) is a major protein in the lipoprotein transport system that plays a well established role in lipids metabolism. apoE gene contains three potential alleles: ε2, ε3 and ε4, forming six genotypes: ε2ε2, ε2ε3, ε2ε4, ε3ε3, ε3ε3 and ε4ε4. The disorder of lipids metabolism is an important feature for nephrotic syndrome (NS). There were some investigations reporting that apoE and its gene polymorphism was associated with NS susceptibility. However, the mechanism was unclear and the association was still controversial. This meta-analysis was performed to evaluate the association between apoE and NS risk in experimental and human studies. A predefined literature search and selection of eligible relevant studies were performed to collect the data from electronic databases, and eligible investigations were synthesized using meta-analysis method. In experimental models, twelve comparisons were included and a definitely positive association was observed between apoE protein expression and NS susceptibility (WMD = 1.88, P < 0.00001). However, in human, there was only two studies included for meta-analysis and a positive association between apoE protein expression and NS susceptibility wasn't found (OR = 108.10, P = 0.32). Interestingly, ε3ε3, ε3ε4, ε3 and ε4 were associated with NS susceptibility (ε3ε3: OR = 0.56, P = 0.002; ε3ε4: OR = 1.91, P = 0.02; ε3: OR = 0.61, P = 0.001; ε4: OR = 1.85, P = 0.009). In conclusion, the apoE gene expression was associated with the NS susceptibility in experimental studies, and the apoE ε3ε3, ε3ε4, ε3 and ε4 were associated with the onset of NS in human studies. This study supported that the disorder of apoE was one of the possible causes for NS risk. However, more studies should be performed to investigate this relationship in the future.

Apo E gene polymorphism on development of diabetic nephropathy

Type 2 diabetes causes premature morbidity and mortality due to the complications of atherosclerosis and diabetic nephropathy (DN). Polymorphism of Apo E gene is known to influence lipid metabolism. Apo E is polymorphic, consisting of three common isoforms (epsilon2, epsilon3 and epsilon4) encoded by three alleles (2, 3 and 4) in exon 4 on chromosome 19. The aim of this study was to investigate the effect of Apo E polymorphism as a prognostic risk factor for the development of DN. A total of 108 NIDDM patients were recruited from the Nephrology and Endocrinology Departments of our hospital. All subjects were divided into three groups: Group I: diabetes with nephropathy (n:37), group II: diabetes without nephropathy (n:71), group III: controls (n:46). Apo E genotypes were determined by real-time PCR. The epsilon4 allele frequency was significantly higher in-group I (10.8%) than in-group III (2.2%), (p < 0.05). In diabetics without nephropathy, the total cholesterol and LDL cholesterol levels were significantly lower in subjects with epsilon2 alleles than epsilon3 and epsilon4 alleles. In conclusion, the present prospective study indicates that the epsilon4 allele of the Apo E polymorphism is one of the prognostic risk factors involved in the development of DN with type 2 diabetes mellitus.

Apolipoprotein E and renal disease

Apolipoprotein E (ApoE) is a major constituent of plasma lipoproteins with many biological actions of great significance. Beyond the known influence of ApoE polymorphisms on serum lipid profile, the pathogenesis of atherosclerosis, and the development of neurodegenerative disorders, ApoE also has a major role in the pathogenesis and progression of a variety of renal diseases, as well as in the atherosclerotic complications associated with them. Briefly, the polymorphisms of ApoE are major determinants of plasma lipid levels in uremic patients. They may affect the risk for cardiovascular disease in this population, predispose to the development of diabetic nephropathy, influence the severity of certain glomerulopathies, and regulate mesangial and glomerular functions locally in the kidney microenvironment. Finally, certain mutations of the ApoE gene are associated with a recently described nephropathy, termed lipoprotein glomerulopathy.