Depletion of ApoA5 aggravates spontaneous and diet-induced nonalcoholic fatty liver disease by reducing hepatic NR1D1 in hamsters

Background: ApoA5 mainly synthesized and secreted by liver is a key modulator of lipoprotein lipase (LPL) activity and triglyceride-rich lipoproteins (TRLs). Although the role of ApoA5 in extrahepatic triglyceride (TG) metabolism in circulation has been well documented, the relationship between ApoA5 and nonalcoholic fatty liver disease (NAFLD) remains incompletely understood and the underlying molecular mechanism still needs to be elucidated. Methods: We used CRISPR/Cas9 gene editing to delete Apoa5 gene from Syrian golden hamster, a small rodent model replicating human metabolic features. Then, the ApoA5-deficient (ApoA5-/-) hamsters were used to investigate NAFLD with or without challenging a high fat diet (HFD). Results: ApoA5-/- hamsters exhibited hypertriglyceridemia (HTG) with markedly elevated TG levels at 2300 mg/dL and hepatic steatosis on a regular chow diet, accompanied with an increase in the expression levels of genes regulating lipolysis and small adipocytes in the adipose tissue. An HFD challenge predisposed ApoA5-/- hamsters to severe HTG (sHTG) and nonalcoholic steatohepatitis (NASH). Mechanistic studies in vitro and in vivo revealed that targeting ApoA5 disrupted NR1D1 mRNA stability in the HepG2 cells and the liver to reduce both mRNA and protein levels of NR1D1, respectively. Overexpression of human NR1D1 by adeno-associated virus 8 (AAV8) in the livers of ApoA5-/- hamsters significantly ameliorated fatty liver without affecting plasma lipid levels. Moreover, restoration of hepatic ApoA5 or activation of UCP1 in brown adipose tissue (BAT) by cold exposure or CL316243 administration could significantly correct sHTG and hepatic steatosis in ApoA5-/- hamsters. Conclusions: Our data demonstrate that HTG caused by ApoA5 deficiency in hamsters is sufficient to elicit hepatic steatosis and HFD aggravates NAFLD by reducing hepatic NR1D1 mRNA and protein levels, which provides a mechanistic link between ApoA5 and NAFLD and suggests the new insights into the potential therapeutic approaches for the treatment of HTG and the related disorders due to ApoA5 deficiency in the clinical trials in future.

Genetic assessment using whole-exome sequencing for a young hypertriglyceridemic patient with repeated acute pancreatitis

Hypertriglyceridemia is caused not only by environmental factors but also by genetic factors. Severe hypertriglyceridemia is prone to complications of acute pancreatitis. Here, we report a whole-exome sequencing (WES) analysis for a young hypertriglyceridemic patient with recurrent acute pancreatitis and the patient's mother. A 28-year-old hypertriglyceridemic female was admitted to our hospital. At 23 years old, a health checkup clarified her hypertriglyceridemia. At the age of 26 and 27, she had repeated acute pancreatitis with severe hypertriglyceridemia (serum triglyceride level were 3,888 mg/dL and 12,080 mg/dL, respectively). The patient's BMI was 29.0 kg/m², and blood samples under fibrate medication showed triglyceride 451 mg/dL and HbA1c 7.2%. Type V dyslipidemia became more apparent at postprandial state. The WES analysis showed that the patients had two heterozygous variants in Apolipoprotein A5 (APOA5) gene (p.G185C and p.V153M), a heterozygous variant in Apolipoprotein E (APOE) gene (p.R176C), three heterozygous variants in Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene (p.T1220I, p.R1453W and p.V470M). On the other hand, her mother, who had moderate hypertriglyceridemia without acute pancreatitis, had a heterozygous variant in APOA5 gene (p.G185C) and two heterozygous variants in CFTR gene (p.T1220I and p.V470M). These results suggest that the more severe pathology of the patient than her mother might be due to the possible compound heterozygous APOA5 variants, the heterozygous APOE variant, and the possible compound heterozygous CFTR variants. In this case, WES analyses were useful to evaluate not only the causative genes of hypertriglyceridemia (APOA5 and APOE) but also the genes involved in the development of acute pancreatitis (CFTR) simultaneously.

Apolipoprotein A5 gene polymorphism (rs662799) and cardiovascular disease in end-stage kidney disease patients

Background

Plasma triglyceride (TG) levels are a significant risk factor for cardiovascular disease (CVD). The APOA5 gene is one of the crucial factors in plasma TG metabolism regulation. The rs662799 polymorphism in the APOA5 gene has been reported to be associated with cardiovascular disease. The goal of this study was to evaluate the potential association of this variant with CVD in patients with end-stage kidney disease. 

Methods

In this case–control study the polymorphism was analyzed using the PCR–RFLP method in 800 consecutive patients with ESKD and 500 healthy controls. The genotype and allele distribution was compared between subgroups of patients with CVD (552) versus those without CVD (248).

Results

The frequency of the minor allele (C) in the healthy individuals was 9% compared to 12% in ESRD group (p = 0.09). The difference between groups was slightly higher for CC homozygote (3.5% versus 1.6%, p = 0.042). The ESKD patient group was analyzed according to the presence or absence of CVD. The significant differences in the polymorphism distribution were revealed in this analysis. The frequency of the C allele in the CVD + subgroup was 14% compared to 6% in CVD- patients (p = 0.001). In the CVD + subgroup the ORs (95% CI) for the C allele and CC genotype were 2.41 (1.61–3.6), p < 0.001 and 3.13 (1.07–9.14), p = 0.036, respectively. This indicates to the association of the variant C allele with cardiovascular disease in ESKD patients. The CC homozygotes have a threefold higher odds of CVD compared to TT homozygotes. The highest frequency of the C allele (18%) was observed in subgroup of patients with diabetic nephropathy, with OR (95% CI) 3.40 (2.13–5.43), p < 0.001.The presence of minor allele (CC and CT genotypes) was significantly associated with increased plasma triglyceride levels (p < 0.001 for both CVD + and CVD- groups).

Conclusion

The present study demonstrated the effect of rs662799 polymorphism on plasma TG levels and its association with the development of cardiovascular disease in ESKD patients.

Apolipoprotein A5 ameliorates MCT induced pulmonary hypertension by inhibiting ER stress in a GRP78 dependent mechanism

Background

Pulmonary arterial hypertension (PAH) is a chronic, progressive lung vascular disease accompanied by elevated pulmonary vascular pressure and resistance, and it is characterized by increased pulmonary artery smooth muscle cell (PASMC) proliferation. Apolipoprotein A5 (ApoA5) improves monocrotaline (MCT)-induced PAH and right heart failure; however, the underlying mechanism remains unknown. Here we speculate that ApoA5 has a protective effect in pulmonary vessels and aim to evaluate the mechanism.

Methods

ApoA5 is overexpressed in an MCT-induced PAH animal model and platelet-derived growth factor (PDGF)-BB-induced proliferating PASMCs. Lung vasculature remodeling was measured by immunostaining, and PASMC proliferation was determined by cell counting kit‐8 and 5‐ethynyl‐2'‐deoxyuridine5‐ethynyl‐2'‐deoxyuridine incorporation assays. Coimmunoprecipitation-mass spectrometry was used to investigate the probable mechanism. Next, its role and mechanism were further verified by knockdown studies.

Results

ApoA5 level was decreased in MCT-induced PAH lung as well as PASMCs. Overexpression of ApoA5 could help to inhibit the remodeling of pulmonary artery smooth muscle. ApoA5 could inhibit PDGF-BB-induced PASMC proliferation and endoplasmic reticulum stress by increasing the expression of glucose-regulated protein 78 (GRP78). After knocking down GRP78, the protecting effects of ApoA5 have been blocked.

Conclusion

ApoA5 ameliorates MCT-induced PAH by inhibiting endoplasmic reticulum stress in a GRP78 dependent mechanism.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01680-4.

Olanzapine leads to nonalcoholic fatty liver disease through the apolipoprotein A5 pathway

The antipsychotic drug olanzapine was reported to induce nonalcoholic fatty liver disease (NAFLD), whereas the underlying mechanism remains incompletely understood. This study investigated whether apolipoprotein A5 (apoA5) and sortilin, two interactive factors involved in NAFLD pathogenesis, are implicated in olanzapine-induced NAFLD. In our study, at week 8, olanzapine treatment successfully induced hepatic steatosis in female C57 BL/6 J mice, which was independent of body weight gain. Likewise, olanzapine effectively mediated hepatocyte steatosis in HepG2 cells characterized by substantially elevated intracellular lipid droplets. Increased plasma triglyceride concentration and decreased plasma apoA5 levels were observed in mice treated with 8-week olanzapine. Surprisingly, olanzapine markedly enhanced hepatic apoA5 protein levels in mice, without a significant effect on rodent hepatic ApoA5 mRNA. Our in vitro study showed that olanzapine reduced apoA5 protein levels in the medium and enhanced apoA5 protein levels in hepatocytes, whereas this drug exerted no effect on hepatocyte APOA5 mRNA. By transfecting APOA5 siRNA into HepG2 cells, it was demonstrated that APOA5 knockdown effectively reversed olanzapine-induced hepatocyte steatosis in vitro. In addition, olanzapine drastically increased sortilin mRNA and protein levels in vivo and in vitro. Interestingly, SORT1 knockdown reduced intracellular apoA5 protein levels and increased medium apoA5 protein levels in vitro, without affecting intracellular APOA5 mRNA levels. Furthermore, SORT1 knockdown greatly ameliorated hepatocyte steatosis in vitro. This study provides the first evidence that sortilin inhibits the hepatic apoA5 secretion that is attributable to olanzapine-induced NAFLD, which provides new insight into effective strategies against NAFLD for patients with schizophrenia administered olanzapine.

The APOA5-rs662799 Polymorphism Is a Determinant of Dyslipidemia in Vietnamese Primary School Children

Apolipoprotein A-V encoded by apolipoprotein 5 (APOA5) gene plays an important role in lipid metabolism, especially in the regulation of plasma triglycerol levels. The study aimed to evaluate the association of the APOA5-rs662799 polymorphism with dyslipidemia in Vietnamese children and the potential modification of obesity-related traits (body mass index, waist circumference, hip circumference, and waist-to-hip ratio) on this association. A case-control study was conducted with a total of 154 dyslipidemia cases and 389 controls at the age of 6 to 10 recruited at 31 primary schools in Hanoi city of Vietnam. Genotype for APOA5-rs662799 polymorphism was determined by the restriction fragment length polymorphism analysis. The association of APOA5-rs662799 polymorphism with dyslipidemia adjusting for age, sex, residence, and obesity-related traits was analyzed by binary logistic regression analysis. The results showed that in comparison with T/T and T/C carriers, the C/C carriers had a higher concentration of serum TAG in cases (p =0.049). Carriers of the C allele (C/C + T/C) had higher risk for developing dyslipidemia and hypertriglyceridemia than subjects with T/T genotype (odds ratio, OR = 1.7, p =0.0062 and OR = 1.6, p = 0.026, respectively). The association remained significant after adjusting for age, gender, residence, and obesity status (OR = 1.75, p = 0.006 and OR = 1.53, p = 0.049, respectively) or other obesity-related traits. The study suggested that the APOA5-rs662799 polymorphism may be a determinant of dyslipidemia and hypertriglyceridemia in Vietnamese children, independent of obesity-related traits.

Gene-environment interaction between APOA5 c.553G>T and pregnancy in hypertriglyceridemia-induced acute pancreatitis

BACKGROUND

The etiology of hypertriglyceridemia (HTG) and, consequently, HTG-induced acute pancreatitis (HTG-AP), is complex.

OBJECTIVE

Herein, we explore a possible gene-environment interaction between APOA5 c.553G>T (p.185Gly>Cys, rs2075291), a common variant associated with altered triglyceride levels, and pregnancy in HTG-AP.

METHODS

We enrolled 318 Chinese HTG-AP patients and divided them into 3 distinct groups: Group 1, male patients (n = 183); Group 2, female patients whose disease was unrelated to pregnancy (n = 105); and Group 3, female patients whose disease was related to pregnancy (n = 30). APOA5 rs2075291 genotype status was determined by Sanger sequencing. A total of 362 healthy Han Chinese subjects were used as controls. Data on body mass index, peak triglyceride level, age of disease onset, episode number, and clinical severity of HTG-AP were collected from each patient. Multiple comparisons, between patient groups, between patient groups and controls, or within each patient group, were performed.

RESULTS

A robust association of APOA5 rs2075291 with HTG-AP in general, and HTG-AP during pregnancy in particular, was demonstrated. The minor T allele showed a stronger association with Group 3 patients than with either Group 1 or Group 2 patients. This stronger association was due mainly to the much higher frequency of TT genotype in Group 3 patients (20%) than that (<6%) in Group 1 and Group 2 patients. Moreover, the TT genotype was associated with a significantly higher peak triglyceride level in Group 3 patients compared with the GG genotype.

CONCLUSION

Our findings provide evidence for an interaction between APOA5 rs2075291 and pregnancy in HTG-AP.

Emerging evidences for the opposite role of apolipoprotein C3 and apolipoprotein A5 in lipid metabolism and coronary artery disease

Apolipoprotein C3 (apoC3) and apolipoprotein A5 (apoA5), encoded by APOA1/C3/A4/A5 gene cluster, are two critical regulators of plasma triglyceride (TG) metabolism. Deficiency of apoC3 or apoA5 led to significant decreased or increased plasma TG levels, respectively. Recent studies indicated apoC3 and apoA5 also played roles in plasma remnant cholesterol, high density lipoprotein (HDL) and hepatic TG metabolisms. Moreover, large scale population genetic studies indicated that loss of function mutations in APOC3 and APOA5 gene conferred decreased and increased risk of coronary artery disease (CAD), respectively. This manuscript mainly reviewed existing evidences suggesting the opposite role of apoC3 and apoA5 in lipid metabolism and CAD risk, and discussed the potential correlation between these two apolipoproteins.

New insights into apolipoprotein A5 in controlling lipoprotein metabolism in obesity and the metabolic syndrome patients

Apolipoprotein A5 (apoA5) has been identified to play an important role in lipid metabolism, specifically in triglyceride (TG) and TG-rich lipoproteins (TRLs) metabolism. Numerous evidence has demonstrated for an association between apoA5 and the increased risk of obesity and metabolic syndrome, but the mechanism remains to be fully elucidated. Recently, several studies verified that apoA5 could significantly reduce plasma TG level by stimulating lipoprotein lipase (LPL) activity, and the intracellular role of apoA5 has also been proved since apoA5 is associated with cytoplasmic lipid droplets (LDs) and affects intrahepatic TG accumulation. Furthermore, since adipocytes provide the largest storage depot for TG and play a crucial role in the development of obesity, we could infer that apoA5 also acts as a novel regulator to modulate TG storage in adipocytes. In this review, we focus on the association of gene and protein of apoA5 with obesity and metabolic syndrome, and provide new insights into the physiological role of apoA5 in humans, giving a potential therapeutic target for obesity and associated disorders.

Apolipoprotein A5 gene polymorphisms are associated with non-alcoholic fatty liver disease

BACKGROUND

Several studies have reported that apolipoprotein A5 (APOA5) is involved in the development of non-alcoholic fatty liver disease (NAFLD). However, no research has been performed regarding the association between APOA5 polymorphisms and the risk of NAFLD. This study aimed to explore the association between APOA5 gene polymorphisms and NAFLD in a Chinese Han population.

METHODS

Genotypes of the SNPs (rs10750097, rs1263173, rs17120035, rs3135507 and rs662799) of APOA5 in 232 NAFLD patients and 188 healthy controls were determined using polymerase chain reaction (PCR) analysis. Clinical characteristics were measured using biochemical methods.

RESULTS

The five single nucleotide polymorphisms (SNPs) (rs10750097, rs1263173, rs17120035, rs3135507 and rs662799) of APOA5 showed no significant association with NAFLD (P > 0.05). The rs10750097 with G allele showed a higher serum level of alkaline phosphatase (ALP) compared with C allele in overall series and NAFLD patients (P < 0.05). The rs1263173(A/A) carriers showed a higher level of glucose compared to the non-carriers in overall series (P < 0.05). The rs17120035(T/T) carriers showed a lower plasma TG level in overall series and NAFLD patients (P < 0.05), and the rs662799(G/G) carriers showed higher levels of plasma triglyceride (TG), ALP, and lower level of high-density lipoprotein (HDL) compared to non-carriers in NAFLD patients (P < 0.05). No significant difference were observed on the clinic parameters of APOA5 rs3135507(T/T) carriers in both group of overall series and NAFLD patients (P > 0.05).

CONCLUSIONS

The five SNPs (rs10750097, rs1263173, rs17120035, rs3135507 and rs662799) of APOA5 gene are not associated with the risk of NAFLD in the Chinese Han population. The genotypes of rs10750097(G/G), rs1263173(A/A), rs17120035(T/T), and rs662799(G/G) performed a significant effect on clinic characteristics in overall series and NAFLD patients, indicating that these polymorphisms may be associated with NAFLD.

Relationship of Serum Apolipoprotein A-V Levels, Oxidative Stress and Inflammatory Biomarkers with Hypertriglyceridemia in Type 2 Diabetes Mellitus

BACKGROUND

Serum levels of triglycerides (TGs) are often found to be raised in type 2 diabetes mellitus (T2DM). TG levels ≥ 2.2 mM, systemic inflammation and oxidative stress (OS) are known to increase the risk of incident cardiovascular disease (CVD) substantially. In recent years, apolipoprotein A-V (Apo A-V protein) has attracted considerably as a modulator of circulating TG levels.

OBJECTIVES

The study was conducted in order to evaluate the levels of Apo A - V proteins and markers of inflammation and OS in patients of T2DM with and without hypertriglyceridemia (HTG) and also to assess correlation between them.

METHODS

T2DM patients were categorized into two groups of 40 participants, according to criteria for risk of CVD: group 1/ controls (TG ≤ 1.65 mM, n = 40) and group 2/ cases (TG ≥ 2.2 mM, n = 40). Despite the routine investigations, serum levels of Apo A-V, interleukin-6 (IL-6) and Insulin were estimated using ELISA, free fatty acids (FFA) with fluorometric assay and malondialdehyde (MDA) was measured using a spectrophotometer. Comparison of levels and correlation between variables was carried out with appropriate statistical tools.

RESULTS

Serum Apo A-V protein levels were found significantly lower (P = 0.04) and MDA was significantly higher (P = 0.049) in cases. MDA correlated with TG levels positively (P = 0.000) and negatively with high density lipoproteins (HDL) (P = 0.000). However Apo A-V protein levels did not correlate with TG levels (P = 0.819, r = -0.027), IL-6 (r = 0.135, P = 0.269), FFA (r = 0.128, P = 0.277) and MDA (r = -0.217, P = 0.073). IL-6 levels significantly and positively correlated with HOMA-IR (r = 0.327, P = 0.004) in the all patients.

CONCLUSIONS

In patients of T2DM, low levels of Apo A-V are associated with HTG, indicating that Apo A-V is linked with TG metabolism. Burden of oxidative stress is greater in HTG of T2DM as is evident from MDA levels and its correlation with TG levels. Since oxidative stress is an important patho-physiological basis which increases the risk of CVD in patients of T2DM with HTG. Further studies are required in order to explore the possible role of Apo A-V in TG metabolism in diabetes.

Identification of a New Single-nucleotide Polymorphism within the Apolipoprotein A5 Gene, Which is Associated with Metabolic Syndrome

Background:

Metabolic syndrome (MetS) is a common disorder which is a constellation of clinical features including abdominal obesity, increased level of serum triglycerides (TGs) and decrease of serum high-density lipoprotein-cholesterol (HDL-C), elevated blood pressure, and glucose intolerance. The apolipoprotein A5 (APOA5) is involved in lipid metabolism, influencing the level of plasma TG and HDL-C. In the present study, we aimed to investigate the associations between four INDEL variants of APOA5 gene and the MetS risk.

Materials and Methods:

In this case–control study, we genotyped 116 Iranian children and adolescents with/without MetS by using Sanger sequencing method for these INDELs. Then, we explored the association of INDELs with MetS risk and their clinical components by logistic regression and one-way analysis of variance analyses.

Results:

We identified a novel insertion polymorphism, c. *282–283 insAG/c. *282–283 insG variant, which appears among case and control groups. rs72525532 showed a significant difference for TG levels between various genotype groups. In addition, there were significant associations between newly identified single-nucleotide polymorphism (SNP) and rs72525532 with MetS risk.

Conclusions:

These results show that rs72525532 and the newly identified SNP may influence the susceptibility of the individuals to MetS.

Hepatitis B virus inhibits apolipoprotein A5 expression through its core gene

Background

Hepatitis B virus (HBV) infection causes lipid metabolism disorders. Apolipoprotein A5 (ApoA5) is a new apolipoprotein family member that plays an important role in the regulation of lipid metabolism. The present study was to investigate the impact of HBV on ApoA5 expression and its regulatory mechanism.

Methods

Reverse transcription polymerase chain reaction (RT-PCR) and western blotting were used to measure ApoA5 mRNA and protein expression in HepG2 and HepG2.2.15 cells. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum ApoA5 levels in healthy individuals and HBV patients. HBV infectious clone pHBV1.3 or individual plasmids expressing the HBV genome was cotransfected with the ApoA5 promoter pGL3-Apo5-LUC plasmid into HepG2 cells to assess the luciferase activity. RT-PCR and western blotting methods were used to detect Apo5 mRNA and protein expression, respectively.

Results

The ApoA5 mRNA and protein expression levels were decreased in HepG2.2.15 cells compared with the control HepG2 cells. The serum ApoA5 levels were 196.4 ± 28.7 μg/L in the healthy individuals and 104.5 ± 18.3 μg/L in the HBV patients, statistical analysis showed that the ApoA5 levels were significantly lower in HBV patients than in the healthy individuals (P < 0.05). pHBV1.3 and its core gene inhibited ApoA5 promoter activity and mRNA and protein expression in HepG2 cells.

Conclusion

HBV inhibits ApoA5 expression at both the transcriptional and translational levels through its core gene.

Apolipoprotein A5 fifteen years anniversary: Lessons from genetic epidemiology

Apolipoprotein A5 (APOA5) is a small protein, expressed predominantly in the liver. In plasma, it is located on triglyceride rich lipoprotein particles (chylomicrones and VLDL) and on HDL. Plasma concentration of apolipoprotein A5 is very low, suggesting rather regulatory (activation of lipoprotein lipase, …) than structural function. APOA5 is an important determinant of plasma triglyceride concentration; this effect has been confirmed both on animal models, as well as on human studies. Minor alleles of three commonly analysed variants within this gene (rs662799, rs3135506, rs2075291) are associated with higher plasma TG values and increased risk of myocardial infarction, with some important interethnic differences observed. Further roles of APOA5; determination of BMI, diabetes and last but not least nutri- and pharmaco-genetic interactions are suggested, but without the definitive conclusions.

Serum high-density lipoprotein correlates with serum apolipoprotein M and A5 in obstructive sleep apnea hypopnea syndrome

Purpose

The purpose of this study was to investigate the correlation between serum levels of serum apolipoprotein M (ApoM), A5 (ApoA5), and high-density lipoprotein (HDL) in patients with obstructive sleep apnea hypopnea syndrome (OSAHS) and study the effects of nasal continuous positive airway pressure treatment on these serum biomarkers.

Methods

Thirty OSAHS patients and 15 non-OSAHS probands as control were selected for the study. Serum HDL, ApoM, and ApoA5 levels in two groups were detected; differences and association among them were analyzed. Patients with moderate and severe OSAHS underwent 3-month auto-continuous positive airway pressure treatment, and a comparative study was conducted to investigate the changes in blood lipids, serum ApoM, and ApoA5.

Results

In comparison to the control group, the HDL, ApoM, and ApoA5 serum levels were lower (P < 0.05). HDL was positively correlated to ApoM and ApoA5 (P < 0.001), and ApoM was positively correlated to ApoA5 (r = 0.536, P < 0.001). HDL, ApoM, and ApoA5 were significantly increased in the patients of moderate and severe OSAHS after auto-continuous positive airway pressure treatment for 3 months (P < 0.05).

Conclusions

The HDL level was significantly lower in OSAHS patients. The decrease in serum ApoM and ApoA5 in OSAHS patients was correlated to the severity of OSAHS and HDL levels. Auto-continuous positive airway pressure treatment increased serum levels of ApoM, ApoA5, and HDL in OSAHS patients.

Association of APOA5 T1131C polymorphism and risk of coronary artery disease

AIMS

Our research aimed to investigate the relationship between Apolipoprotein A5 (APOA5) T1131C polymorphism and the risk of coronary artery disease (CAD).

METHODS

We searched the relevant articles in databases and 25 ones were chosen. The association between APOA5 T1131C polymorphism and CAD risk was evaluated using odds ratios (ORs) and 95% confidence intervals (95% CIs). The fixed-effect model or random-effect model was applied according to the heterogeneity analysis.

RESULTS

Overall, significant association between CAD risk and APOA5 T1131C polymorphism was found (CC vs. TT: OR=1.47, 95% CI=1.22-1.78; CC+TC vs. TT: OR=1.13, 95% CI=1.07-1.20; CC vs. TT+TC: OR=1.37, 95% CI=1.13-1.66; allele C vs. allele T: OR=1.17, 95% CI=1.09-1.25; TC vs. TT: OR=1.12, 95% CI=1.06-1.20). In the ethnicity subgroup analysis, risk of CAD was observed in all genotypes among Asians (CC vs. TT: OR=1.40, 95% CI=1.17-1.68; CC+TC vs. TT: OR=1.13, 95% CI=1.06-1.20; CC vs. TT+TC: OR=1.30, 95% CI=1.08-1.56; allele C vs. allele T: OR=1.15, 95% CI=1.08-1.24; TC vs. TT: OR=1.13, 95% CI=1.06-1.21), While in Caucasians, the similar association was only found in several genotypes. In the subgroup analysis by source of control, we found that APOA5 T1131C polymorphism could increase the risk of CAD in population-based (PB) genetic group (CC vs. TT: OR=1.54, 95% CI=1.29-1.84; CC+TC vs. TT: OR=1.15, 95% CI=1.08-1.23; CC vs. TT+TC: OR=1.45, 95% CI=1.19-1.76; allele C vs. allele T: OR=1.19, 95% CI=1.12-1.25; TC vs. TT: OR=1.14, 95% CI=1.06-1.22). There was no correlation found in hospital-based (HB) genetic group yet.

CONCLUSION

APOA5 T1131C polymorphism might be significantly associated with susceptibility to CAD.

Genetic variants of apolipoprotein A5 T-1131C and apolipoprotein E common polymorphisms and their relationship to features of metabolic syndrome in adult dyslipidemic patients

OBJECTIVES

The aim was to evaluate the relationships of the T-1131C (rs662799) polymorphism variants of apolipoprotein A5 (Apo A5) gene and variants of apolipoprotein E (Apo E) gene common polymorphism (rs429358, rs7412) to signs of metabolic syndrome (MetS).

DESIGN AND METHODS

We examined 590 asymptomatic dyslipidemic patients divided into MetS+ (n=146) and MetS- (n=444) groups according to criteria of NCEP ATPIII Panel. We evaluated genotype frequencies and differences in MetS features between individual groups. Logistic regression analysis was used for the evaluation of Apo A5/Apo E variants as possible risk factors for MetS.

RESULTS

We found no statistical differences between genotype and allele frequencies for both Apo A5 and Apo E polymorphisms between MetS+ and MetS- groups. In all subjects and MetS- group, we confirmed well-known association of the -1131C Apo A5 minor allele with elevated triglycerides (TG, p<0.001). The Apo E gene E2 and E4 variants were associated with higher levels of TG (p<0.01) in comparison to E33 common variant. However, no statistical differences were observed in MetS+ subjects, regardless of significantly higher TG levels in this group. Apo A5/Apo E variant analysis in all dyslipidemic patients revealed significant increase of TG levels in all subgroups in comparison to common -1131T/E3 variant carriers, the most in -1131C/E4 variant subgroup. Logistic regression analysis models showed no association of Apo A5, Apo E and all Apo A5/Apo E variants with metabolic syndrome, even after adjustment for age and sex.

CONCLUSION

Our study refined the role of Apo A5 and Apo E genetic variants in the group of adult dyslipidemic patients. We demonstrate that except of TG, Apo A5 T-1131C (rs662799) and Apo E (rs429358, rs7412) polymorphisms have no remarkable effect on MetS characteristics.

The association between APOA5 haplotypes and plasma lipids is not modified by energy or fat intake: the Czech HAPIEE study

BACKGROUND AND AIMS

Several smaller studies reported interactions between dietary factors and apolipoprotein A5 (APOA5) gene polymorphisms in determination of plasma lipids. We tested interactions between APOA5 haplotypes and dietary intake in determination of plasma triglycerides (TG) and other lipids.

METHODS AND RESULTS

Participants (5487 males and females aged 45-69) were classified according to the number (0, 1, 2+) of minor APOA5 alleles (using T-1131 > C; rs662799 and Ser19 > Trp; rs3135506 polymorphisms) and into three groups of low (bottom 25%), medium (26th-75th percentile) and high (top 25%) of intake of total energy and total, saturated and polyunsaturated fats, assessed by food frequency questionnaire. The age-sex adjusted geometric means of plasma TG increased with the number of minor alleles, from 1.57 (standard error 0.01), to 1.79 (0.02) to 2.29 (0.10) mmol/L (p < 0.00001) but TG did not differ between groups with low, medium and high total energy intake (p = 0.251). TG concentrations were highest in subjects with the combination of 2+ minor alleles and the highest energy intake (mean 2.59 [0.19], compared with 1.62 [0.03] in subjects with lowest energy intake and no minor allele) but the interaction between energy intake and APOA5 haplotypes was not statistically significant (p = 0.186). Analogous analyses with total, saturated and polyunsaturated fat intake yielded similar nonsignificant results. Effects of APOA5 and dietary intakes on total and HDL cholesterol were weaker and no interactions were significant.

CONCLUSION

In this Slavic Caucasian population sample, we did not detect the hypothesized interaction between common SNPs within the APOA5 gene and diet in determination of blood lipids.

Genotype-phenotype relationships in patients with type I hyperlipoproteinemia

CONTEXT

Type I hyperlipoproteinemia (T1HLP) is a rare, autosomal recessive disorder characterized by extreme hypertriglyceridemia that fails to respond to lipid-lowering agents, predisposing to frequent attacks of acute pancreatitis. Mutations in lipoprotein lipase (LPL), apolipoprotein CII (APOC2), lipase maturation factor 1 (LMF1), glycosyl-phosphatidylinositol anchored high-density lipoprotein-binding protein 1 (GPIHBP1), and apolipoprotein AV (APOA5) cause T1HLP, but we lack data on phenotypic variations among the different genetic subtypes.

OBJECTIVE

To study genotype-phenotype relationships among subtypes of T1HLP patients.

DESIGN/INTERVENTION

Genetic screening for mutations in LPL, APOC2, GPIHBP1, LMF1, and APOA5.

SETTING

Tertiary referral center.

PATIENTS

Ten patients (7 female, 3 male) with chylomicronemia, serum triglyceride levels about 2000 mg/dL, and no secondary causes of hypertriglyceridemia.

MAIN OUTCOME MEASURES

Genotyping and phenotypic features.

RESULTS

Four patients harbored homozygous or compound heterozygous mutations in LPL, 3 had homozygous mutations in GPIHBP1, and 1 had a heterozygous APOA5 mutation. We failed to fully identify the genetic etiology in 2 cases: 1 had a heterozygous LPL mutation only and another did not have any mutations. We identified 2 interesting phenotypic features: the patient with heterozygous APOA5 mutation normalized triglyceride levels with weight loss and fish oil therapy, and all 7 female patients were anemic.

CONCLUSIONS

Our data suggest the possibility of novel loci for T1HLP. We observed that heterozygous APOA5 mutation can cause T1HLP but such patients may unexpectedly respond to therapy, and females with T1HLP suffer from anemia. Further studies of larger cohorts may elucidate more phenotype-genotypes relationships among T1HLP subtypes.