Association between MspI polymorphism of the APO AI gene and Type 2 diabetes mellitus

[Influence of rs670 variant of APOA1 gene on serum HDL response to an enriched-polyunsaturated vs. an enriched-monounsaturated fat hypocaloric diet]

Introduction

Background and objectives: genetic variants of the APOA1 gene have been related to lipid profile in obese subjects. Our aim was to analyze the effects of the rs670 APOA1 gene polymorphism on metabolic changes secondary to an enriched-polyunsaturated fat vs. an enriched-monounsaturated fat hypocaloric diet. Methods: 360 Caucasian obese subjects were randomly allocated to two groups. One group received an enriched-polyunsaturated fat (diet P) and the other an enriched-monounsaturated fat hypocaloric diet (diet M) during 12 weeks. The effects on serum biomarkers related to lipid and carbohydrate metabolism were evaluated before and after the dietary intervention. Results: after both diets, body mass index, weight, fat mass, waist circumference, systolic blood pressure, plasma leptin concentration, and waist circumference decreased in all patients. After 12 weeks of intervention with diet P, plasma insulin levels and HOMA-IR decreased in A-allele carriers: delta: -7.3 ± 2.2 IU/L (p = 0.01), and delta: -2.8 ± 0.5 units (p = 0.02), respectively. The same changes in delta were observed after diet M in A-allele carriers: insulin delta: -5.9 ± 1.2 IU/L (p = 0.01), and HOMA-IR delta: -2.1 ± 0.8 units (p = 0.02). In A-allele carriers, LDL-cholesterol decreased and HDL-cholesterol increased after the dietary intervention with diet P: delta: -12.1 ± 4.3 mg/dL (p = 0.01), and delta: 2.6 ± 0.7 mg/dL (p = 0.01), respectively. No differences in lipid profile were observed after diet M. These improvements were not observed in non-A-allele carriers after both interventions. Conclusions: our study showed the association of the rs670 ApoA1 polymorphism with insulin resistance changes as induced by both diets. An enriched-polyunsaturated fat diet produced an additional improvement of HDL-cholesterol and LDL-cholesterol in A-allele carriers.

Association of rs670 variant of APOA1 gene with lipid profile and insulin resistance after 9 months of a high protein/low carbohydrate vs a standard hypocaloric diet

BACKGROUND & AIMS

A common G-to-A transition (rs670) in the APOA1 gene has been related with metabolism. We evaluate the association of this SNP with changes in lipid profile and insulin resistance in response to two diets.

METHODS

268 obese patients were randomly allocated to a high protein/low carbohydrate -Diet HP- vs. a standard hypocaloric diet -Diet S- for 9 months. Anthropometric and biochemical status were evaluated at 3 and 9 months.

RESULTS

179 subjects (66.8%) had the genotype GG, 79 patients GA (29.4%) and 10 subjects AA (3,8%). With both diets: the decrease of BMI, weight, waist circumference, fat mass was higher in A allele carriers than non-carriers. Also on both diets A allele carriers showed greater improvements in total cholesterol (-19.0 ± 2.5 mg/dl (non-A allele carriers -12.1 ± 2.0 mg/dl:p = 0.02 after Diet HP) and -13.1 ± 2.1 mg/dl (non-A allele carriers -8.9 ± 1.1 mg/dl:p = 0.02 after Diet S)), LDL-cholesterol (-18.0 ± 2.1 mg/dl (non-A allele carriers -8.3 ± 2.2 mg/dl:p = 0.01 after Diet HP) and -12.0 ± 1.5 mg/dl (non-A allele carriers -6.3 ± 2.3 mg/dl:p = 0.01 after Diet S)), insulin (-2.5 ± 0.2 mUI/L (in non A allele -1.8 ± 0.2 mUI/L:p = 0.01 after Diet HP) and -2.1 ± 0.1 mUI/L (non A allele carriers -1.2 ± 0.3 mUI/L:p = 0.01 after Diet S)), HOMA-IR (-1.3 ± 0.3 units (non A allele group -0.8 ± 0.2:p = 0.03 after Diet HP) and -1.1 ± 0.1 units (non A allele carriers -0.3 ± 0.2 mg/dl:p = 0.01 after Diet S)) than non-A allele carriers.

CONCLUSIONS

A allele carriers of rs670 ApoA1 polymorphism showed a higher decrease of insulin resistance, LDL cholesterol and adiposity induced by two different hypocaloric diet than non A allele carriers.

Role of rs670 variant of APOA1 gene on metabolic response after a high fat vs. a low fat hypocaloric diets in obese human subjects

BACKGROUND & AIMS

A common G-to-A transition located 75 base pairs upstream (rs670) from transcription start site of the APOA1 gene has been related with some metabolic parameters. Our aim was to analyze the effects of rs670 APOA1 gene polymorphism on lipid profile and metabolic changes after two different hypocaloric diets.

METHODS

282 obese subjects were randomly allocated during 12 weeks (Diet HF - high fat diet vs. Diet LF - low fat diet). Anthropometric and biochemical status were evaluated.

RESULTS

Body mass index, weight, fat mass, waist circumference, systolic blood pressure, leptin levels and waist circumference decreased in all patients in average after both diets. In A allele carriers after 12 weeks with both diets, insulin levels (Delta diet HF: -5.3 + 1.2 UI/L; P = 0.02 and Delta diet LF: -5.8 + 1.3 UI/L; P = 0.02) and HOMA-IR (Delta diet HF: -2.9 + 0.8 units; P = 0.01 and Delta diet LF: -2.2 + 0.9 units; P = 0.03) improved in a significant way. With the low fat diet, A allele carriers showed a statistical improvement in HDL-cholesterol levels (Delta: 4 + 1 mg/dl; P = 0.03).

CONCLUSIONS

Our study showed the association of rs670 ApoA1 polymorphism with a decrease of insulin resistance induced by both diets and provided additional evidence on HDL-cholesterol increase after a LF hypocaloric diet in A allele carriers.

Role of rs670 variant of APOA1 gene on lipid profile, insulin resistance and adipokine levels in obese subjects after weight loss with a dietary intervention

OBJECTIVE

The aim of this study was to analyze the effects of rs670 APOA1 gene polymorphism on obesity parameters, lipid profile, glucose metabolism markers, blood pressure and adipokine levels after a hypocaloric diet with Mediterranean pattern.

MATERIAL AND METHODS

A population of 82 obese patients was studied before and after 12 weeks on a hypocaloric diet (500 kcal per day) in an interventional study of one arm. GG and GA + AA subjects receiving the same diet. Anthropometric measures and biochemical parameters (lipid profile, glucose metabolism, blood pressure and adipokine levels) were measured. Genotype of ApoA1 gene polymorphism (rs670) was evaluated. The A allele is the risk allele.

RESULTS

After dietary intervention and in both genotype groups (GG vs. GA + AA), body mass index (BMI) (delta: -1.0 ± 0.8 kg/m² vs. -1.4 ± 1.0 kg/m²: p = 0.02), weight (delta: -2.6 ± 2.1 kg vs. -3.6 ± 2.2 kg: p = 0.03), fat mass (delta: -1.6 ± 1.1 kg vs. -3.2 ± 1.0 kg: p = 0.01) and waist circumference (delta: -1.8 ± 0.6 cm vs. -2.2 ± 1.1 cm: p = 0.02) decreased. The decrease of the anthropometric parameters was higher in A allele carriers than non-A allele carriers. In A allele carriers, total cholesterol (delta: -11.1 ± 7.1 mg/dl vs. -20.1 ± 9.0 mg/dl: p = 0.02), LDL cholesterol (delta: -10.7 ± 4.1 mg/dl vs. -21.2 ± 8.0 mg/dl: p = 0.01), insulin levels (delta: -0.6 ± 0.8 UI/L vs. 3.7 ± 1.1 UI/L; p = 0.002) and insulin resistance with HOMA-IR (delta: -0.2 ± 0.3 units vs. 0.8 ± 0.4 units; p = 0.01) decreased. The improvement of leptin was similar in both genotype groups. Resistin and adiponectin levels remained unchanged after dietary intervention.

CONCLUSION

In this study the APOA1 (rs670) gene showed important effects on body weight, adiposity, LDL-cholesterol levels and insulin resistance after 12 weeks of the dietary intervention.

Implication of the rs670 variant of APOA1 gene with lipid profile, serum adipokine levels and components of metabolic syndrome in adult obese subjects

BACKGROUND & AIMS

A G-to-A transition located 75 base pairs upstream (rs670) from transcription start site of the APOA1 gene is related with metabolic parameters. The aim of the present investigation was to describe the association of rs670 with metabolic syndrome and metabolic parameters.

METHODS

The study involved a population of 1000 obese subjects. Measurements of anthropometric parameters, arterial blood pressure, fasting blood glucose, C-reactive protein (CRP), insulin concentration, insulin resistance (HOMA-IR), lipid profile, adipokines levels and prevalence of MetS was recorded. Genotype of ApoA1 gene polymorphism (rs670) was evaluated.

RESULTS

A sample of 1000 obese subjects with a mean BMI of 36.5 ± 5.0 kg/m² was enrolled. In males, weight (delta: 3.3 ± 1.2 kg; p = 0.01), fat mass (delta: 2.7 ± 1.1 kg; p = 0.01), waist circumference (delta: 2.8 ± 1.1 cm; p = 0.02), fasting glucose (delta: 8.9 ± 2.2 mg/dl; p = 0.01), insulin levels (delta: 3.7 ± 1.2 UI/L; p = 0.04) and HOMA-IR (delta: 1.2 ± 1.1 units; p = 0.02) were higher in non-A allele carriers than A allele carriers. In males without A allele, an increased risk of hyperglycemia (OR = 1.40, 95% CI = 1.09-2.09, p = 0.04), percentage of central obesity (OR = 4.55, 95% CI = 1.36-15.39, p = 0.01), percentage of low HDL-C (OR = 2.02, 95% CI = 1.02-4.03, p = 0.03) and prevalence of diabetes mellitus (OR = 2.14, 95% CI = 1.03-5.04, p = 0.03) were reported.

CONCLUSIONS

rs670 of APOA1 gene has a gender specific influence on serum glucose, insulin, HOMA-IR, fat mass, weight and waist circumference. Males without A allele showed high rates of central obesity, low levels of HDL, hyperglycemia and diabetes mellitus.

HDLs, diabetes, and metabolic syndrome

The prevalence of type 2 diabetes mellitus and of the metabolic syndrome is rising worldwide and reaching epidemic proportions. These pathologies are associated with significant morbidity and mortality, in particular with an excess of cardiovascular deaths. Type 2 diabetes mellitus and the cluster of pathologies including insulin resistance, central obesity, high blood pressure, and hypertriglyceridemia that constitute the metabolic syndrome are associated with low levels of HDL cholesterol and the presence of dysfunctional HDLs. We here review the epidemiological evidence and the potential underlying mechanisms of this association. We first discuss the well-established association of type 2 diabetes mellitus and insulin resistance with alterations of lipid metabolism and how these alterations may lead to low levels of HDL cholesterol and the occurrence of dysfunctional HDLs. We then present and discuss the evidence showing that HDL modulates insulin sensitivity, insulin-independent glucose uptake, insulin secretion, and beta cell survival. A dysfunction in these actions could play a direct role in the pathogenesis of type 2 diabetes mellitus.

Gender-specific associations of the APOA1 -75G>A polymorphism with several metabolic syndrome components in Turkish adults

BACKGROUND

Variations in the apolipoprotein A-1 (APOA1) gene, a determinant of plasma high-density lipoprotein cholesterol (HDL-C) and apoA-I levels, may contribute to cardiovascular diseases. We evaluated the effects of a promoter polymorphism (-75G>A) in the APOA1 gene on metabolic syndrome (MetS) components in a Turkish population sample.

METHODS

Randomly selected 1515 Turkish adults (age 49.9±11.8 years, 785 females) were genotyped for -75G>A polymorphism using hybridization probes in Real-Time PCR LC480 device. MetS and atherogenic dyslipidemia were defined using the criteria of ATP III.

RESULTS

The -75AA genotype prevailed in 3.9% of men and 2.4% of women, and was independently associated with significantly higher HDL-C concentrations. Independent associations with the -75GA genotype existed only in men: higher diastolic and systolic blood pressure (BP) levels (p<0.05) were observed in male -75GA heterozygotes. Logistic regression revealed that the GA genotype confers elevated risk for atherogenic dyslipidemia (OR=1.57, 95% Cl 1.06-2.3) after adjustment for associated risk factors. Independent associations with atherogenic dyslipidemia or elevated BP did not emerge in women.

CONCLUSION

APOA1 -75G>A polymorphism is independently related to HDL-C concentrations. Independent associations of the -75GA genotype with elevated BP and atherogenic dyslipidemia were confined to men. These gender-modulated associations suggest novel gene-gender-environmental interactions.

The dyslipidemia-associated SNP on the APOA1/C3/A5 gene cluster predicts post-surgery poor outcome in Taiwanese breast cancer patients: a 10-year follow-up study

Background

Post-surgery therapies are given to early-stage breast cancer patients due to the possibility of residual micrometastasis, and optimized by clincopathological parameters such as tumor stage, and hormone receptor/lymph node status. However, current efficacy of post-surgery therapies is unsatisfactory, and may be varied according to unidentified patient genetic factors. Increases of breast cancer occurrence and recurrence have been associated with dyslipidemia, which can attribute to other known risk factors of breast cancer including obesity, diabetes and metabolic syndrome. Thus we reasoned that dyslipidemia-associated nucleotide polymorphisms (SNPs) on the APOA1/C3/A5 gene cluster may predict breast cancer risk and tumor progression.

Methods

We analyzed the distribution of 5 selected APOA1/C3/A5 SNPs in recruited Taiwanese breast cancer patients (n=223) and healthy controls (n=162). The association of SNP (APOA1 rs670) showing correlation with breast cancer with baseline and follow-up parameters was further examined.

Results

APOA1 rs670 A allele carriage was higher in breast cancer patients than controls (59.64% vs. 48.77%, p=0.038). The rs670 A allele carrying patients showed less favorable baseline phenotype with positive lymph nodes (G/A: OR=3.32, 95% CI=1.77-6.20, p<0.001; A/A: OR=2.58, 95% CI=1.05-6.32, p=0.039) and negative hormone receptor expression (A/A: OR=4.85, 95%CI=1.83-12.83, p=0.001) in comparison to G/G carriers. Moreover, rs670 A/A carrying patients had higher risks in both tumor recurrence (HR=3.12, 95% CI=1.29-7.56, p=0.012) and mortality (HR=4.36, 95% CI=1.52-12.47, p=0.006) than patients with no A alleles after adjustments for associated baseline parameters. Furthermore, the prognostic effect of rs670 A/A carriage was most evident in lymph node-negative patients, conferring to the highest risks of recurrence (HR=4.98, 95% CI=1.40-17.70, p=0.013) and mortality (HR=9.87, 95%CI=1.60-60.81, p=0.014) than patients with no A alleles.

Conclusions

APOA1 rs670 A/A carriage showed poor post-surgery prognosis in Taiwanese lymph node-negative breast cancer patients, whose prognosis were considered better and adjuvant treatment might be less stringent according to currently available assessment protocols. Our findings suggest that APOA1 rs670 indicate a post-surgery risk of breast cancer disease progression, and that carriers of this SNP may benefit from more advanced disease monitoring and therapy regimens than the current regular standards. Furthermore, control of lipid homeostasis might protect APOA1 rs670 minor allele carriers from breast cancer occurrence and progression.

Central obesity in males affected by a dyslipidemia-associated genetic polymorphism on APOA1/C3/A4/A5 gene cluster

BACKGROUND

Central obesity is a rising epidemic, and often occurs in parallel with dyslipidemia. Furthermore, enhancement of ectopic fat deposition has been observed in both human studies and animal models of altered lipidemic control. Though APOA1/C3/A4/A5 genetic polymorphisms are associated with dyslipidemia, their effect on central obesity is less known.

METHOD

The anthropometric and metabolic parameters were taken from obese (body mass index (BMI) 25 kg m(-2)) and non-obese healthy (BMI <25) Taiwanese patients at the initiation weight-loss intervention and 6 months later. The effects of APOA1/C3/A4/A5 genetic polymorphisms were analyzed cross-sectionally and longitudinally. Gender contributions were specifically examined.

PATIENTS

Three hundred and ninety-eight participants (obese n=262; non-obese healthy n=136) were recruited in total, and 130 obese patients underwent weight-loss treatments.

RESULTS

APOA5 rs662799 minor allele carriage was associated with unfavorable metabolic profiles in obese but not non-obese individuals at baseline. Further analysis identified gender-genotype interactions in waist-hip ratio (WHR), and that one rs662799 minor allele increased 0.032 WHR unit in obese males as analyzed by linear regression adjusted for age, BMI and plasma triglyceride (TG) (95% confidence interval (CI)=0.014-0.050, P=0.001). The rs662799-associated WHR elevation resulted in increased frequency of central obesity (WHR 1.0) in rs662799 carrying obese males as analyzed by binary logistic regression adjusted for age, BMI and plasma TG (odds ratio=6.52, 95% CI=1.87-22.73, P=0.003). In contrast, APOA5 rs662799 and central obesity were no longer correlated 6 months into weight-loss treatments, owing to significant WHR reductions in male rs662799 minor allele carriers (P=0.001). Meanwhile, hypertriglyceridemia was more prevalent in both male and female obese rs662799 minor allele carriers at baseline (males, P=0.034, females, P=0.007).

CONCLUSION

This study highlights the gender-specific and weight-sensitive effects of APOA5 rs662799 on central obesity in Taiwanese individuals, and that these effects are dyslipidemia-independent and weight-loss responsive.

Gene-nutrient interactions and gender may modulate the association between ApoA1 and ApoB gene polymorphisms and metabolic syndrome risk

OBJECTIVE

Dyslipidemia is a key feature of the metabolic syndrome (MetS), which is determined by both genetic and dietary factors.

METHODS

We determined the relationships between ApoA1 and ApoB polymorphisms and MetS risk, and whether dietary fat modulates this in the LIPGENE-SU.VI.MAX study of MetS cases and matched controls (n = 1754).

RESULTS

ApoB rs512535 and ApoA1 rs670 major G allele homozygotes had increased MetS risk (OR 1.65 [CI 1.24, 2.20], P = 0.0006; OR 1.42 [CI 1.08, 1.87], P = 0.013), which may be, partly, explained by their increased abdominal obesity and impaired insulin sensitivity (P<0.05) but not dyslipidemia. Interestingly these associations derived primarily from the male GG homozygotes (ApoB rs512535 OR 1.92 [CI 1.31, 2.81], P = 0.0008; ApoA1 rs670 OR 1.50 [CI 1.05, 2.12], P = 0.024). MetS risk was exacerbated among the habitual high-fat consumers (>35% energy) (ApoB rs512535 OR 2.00 [CI 1.14, 3.51], P = 0.015; OR 1.58 [CI 1.11, 2.25], P = 0.012 for ApoA1 rs670). In addition a high monounsaturated fat (MUFA) intake (>14% energy) increased MetS risk (OR 1.89 [CI 1.08, 3.30], P = 0.026 and OR 1.57 [CI 1.10, 2.40], P = 0.014 for ApoB rs512535 and ApoA1 rs670, respectively). MetS risk was abolished among the habitual low-fat consumers (<35% energy). Saturated and polyunsaturated fat intake did not modulate MetS risk.

CONCLUSION

ApoB rs512535 and ApoA1 rs670 may influence MetS risk. Apparent modulation of these associations by gender and dietary fat composition suggests novel gene-gender-diet interactions.

Intake and home use of olive oil or mixed oils in relation to healthy lifestyles in a Mediterranean population. Findings from the prospective Pizarra study

Discordances exist in epidemiological studies regarding the association between the intake of nutrients and death and disease. We evaluated the social and health profile of persons who consumed olive oil in a prospective population cohort investigation (Pizarra study) with a 6-year follow-up. A food frequency questionnaire and a 7 d quantitative questionnaire were administered to 538 persons. The type of oil used in food preparation was determined by direct measurement of the fatty acids in samples obtained from the kitchens of the participants at baseline and after follow-up for 6 years. The fatty acid composition of the serum phospholipids was used as an endogenous marker of the type of oil consumed. Total fat intake accounted for a mean 40 % of the energy (at baseline and after follow-up). The concordance in intake of MUFA over the study period was high. The fatty acid composition of the serum phospholipids was significantly associated with the type of oil consumed and with fish intake. The concentration of polar compounds and polymers, indicative of degradation, was greater in oils from the kitchens where sunflower oil or refined olive oil was used, in oils used for deep frying and in oils that had been reused for frying five times or more. Consumption of olive oil was directly associated with educational level. Part of the discordance found in epidemiological studies between diet and health may be due to the handling of oils during food preparation. The intake of olive oil is associated with other healthy habits.

Effect of the combination of the variants -75G/A APOA1 and Trp64Arg ADRB3 on the risk of type 2 diabetes (DM2)

OBJECTIVE

Numerous genes have been associated with the risk for type 2 diabetes mellitus (DM2). In an attempt to understand how specific variants of different genes interact and intervene in the molecular and physiological mechanisms of disorders such as diabetes or insulin resistance, the search for gene-gene interactions is constantly growing. We searched for a possible interaction between two polymorphisms (Trp64Arg of ADRB3 gene and -75G/A of APOA1gene) and the risk for DM2 in a population from southern Spain.

DESIGN AND METHODS

A cross-sectional study in southern Spain of 1020 people, aged 18-65 years. All persons underwent a clinical, anthropometrical and biochemical evaluation, including an oral glucose tolerance test (OGTT). Insulin resistance was measured by homeostasis model of assessment (HOMA). The polymorphisms -75G/A of APOA1 and Trp64Arg of ADRB3 were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and real-time PCR, respectively.

RESULTS

The genotype frequencies of the -75G/A polymorphism of the APOA1 gene were 62.7% GG, 25.7% GA and 11.6% AA, whereas for the Trp64Arg polymorphism of the ADRB3 gene, they were 87.5% Trp/Trp, 11.7% Trp/Arg and 0.8% Arg/Arg. Subjects with both gene variants had a greater odds ratio (OR) of having DM2 [OR = 5.5; 95% confidence interval (CI) = 1.2-23.5] than persons with one or none of the variants, after adjusting for age, sex, body mass index (BMI) and homeostasis model assessment of insulin resistance (HOMA-IR).

CONCLUSIONS

Joint association of allele -75A (APOA1) and allele Arg64 (ADRB3) increase the risk of DM2 in a population from southern Spain.

Apolipoprotein A-I stimulates AMP-activated protein kinase and improves glucose metabolism

AIMS/HYPOTHESIS

In humans, one of the hallmarks of type 2 diabetes is a reduced plasma concentration of HDL and its major protein component, apolipoprotein A-I (APOA-I). However, it is unknown whether APOA-I directly protects against diabetes. The aim of this study was to characterise the functional role of APOA-I in glucose homeostasis.

METHODS

The effects of APOA-I on phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC), glucose uptake and endocytosis were analysed in C2C12 myocytes. Glucose metabolism was investigated in Apoa-I knockout (Apoa-I (-/-)) mice.

RESULTS

APOA-I was able to stimulate the phosphorylation of AMPK and ACC, and elevated glucose uptake in C2C12 myocytes. APOA-I could be endocytosed into C2C12 myotubes through a clathrin-dependent endocytotic process. Inhibition of endocytosis abrogated APOA-I-stimulated AMPK phosphorylation. In Apoa-I (-/-) mice, AMPK phosphorylation was reduced in skeletal muscle and liver, and expression of gluconeogenic enzymes was increased in liver. In addition, the Apoa-I (-/-) mice had increased fat content and compromised glucose tolerance.

CONCLUSIONS/INTERPRETATION

Our data indicate that APOA-I has a protective effect against diabetes via activation of AMPK. ApoA-I deletion in the mouse led to increased fat mass and impaired glucose tolerance.