Daiana Ibarretxe

Circulating PCSK9 in patients with type 2 diabetes and related metabolic disorders

BACKGROUND PCSK9 is a pivotal molecule in the regulation of lipid metabolism. Previous studies have suggested that PCSK9 expression and its function in LDL receptor regulation could be altered in the context of diabetes. The aim was to assess PCSK9 plasma levels in patients with type 2 diabetes (T2DM) and other related metabolic disorders as well as its relation to the metabolomic profile generated by nuclear magnetic resonance (NMR) and glucose homeostasis. METHODS There were recruited a total of 457 patients suffering from T2DM and other metabolic disorders (metabolic syndrome (MetS), obesity and atherogenic dyslipidaemia (AD) and other disorders). Anamnesis, anthropometry and physical examinations were conducted, and vascular and abdominal adiposity imaging were carried out. Biochemical studies were performed to determine PCSK9 plasma levels 6 weeks after lipid lowering drug wash-out in treated patients. A complete metabolomic lipid profile was also generated by NMR. The rs505151 and rs11591147 genetic variants of PCSK9 gene were identified in patients. RESULTS The results showed that PCSK9 levels are increased in patients with T2DM and MetS (14% and 13%; p<0.005, respectively). Circulating PCSK9 levels were correlated with an atherogenic lipid profile and with insulin resistance parameters. PCSK9 levels were also positively associated with AD, as defined by lipoprotein particle number and size. The rs11591147 genetic variant resulted in lower levels of circulating PCSK9 and LDL cholesterol (LDL-C). CONCLUSIONS PCSK9 plasma levels are increased in T2DM and MetS patients and are associated with LDL-C and other parameters of AD and glucose metabolism.

Circulating PCSK9 levels are positively correlated with NMR-assessed atherogenic dyslipidaemia in patients with high cardiovascular risk

The proprotein convertase subtilisin/kexin type 9 (PCSK9) gene regulates cholesterol homoeostasis by accelerating low-density lipoprotein receptor (LDLR) degradation resulting in the decreased catabolism of low-density lipoprotein (LDL) leading to hypercholesterolaemia. PCSK9 has also been related to other metabolic risk factors such as triglycerides (TGs) and glucose levels and body mass index (BMI). Therefore, our aim was to study the relationship between the PCSK9 and the lipid and lipoprotein profile. We studied 267 diabetic and metabolic syndrome patients who were not receiving any lipid-lowering therapy. We measured circulating lipids, cholesterol in remnant lipoproteins (RLPc) and PCSK9 levels. A detailed lipoprotein profile was determined based on NMR. Plasma PCSK9 levels were significantly and positively correlated with TG (r=0.136, P=0.033), total cholesterol (r=0.219, P<0.001) and apoB (apolipoprotein B; r=0.226, P=0.006) circulating levels and with an atherogenic profile of lipoprotein subclasses. In further detail, circulating PCSK9 levels were positively correlated with large very-low density lipoprotein (VLDL) particles, (r=0.210, P=0.001) and with their remnants, the intermediate-density lipoprotein (IDL) particles (r=0.206, P=0.001); positively correlated with smaller LDL particles (for small LDL: r=0.224, P<0.001; for medium small LDL: r=0.235, P<0.001; and for very small LDL: r=0.220, P<0.001); and with high-density lipoprotein (HDL) particles (r=0.146, P<0.001), which is mainly explained by the PCSK9 correlation with the smallest HDL particles (r=0.130, P=0.037). In addition, circulating PCSK9 levels were positively correlated with the pro-atherogenic circulating RLPc levels (r=0.171, P=0.006). All of the correlations were adjusted by age, gender and BMI. PCSK9 levels are significantly and positively correlated with atherogenic lipoproteins such as large VLDL, IDL, the smallest LDL, the smallest HDL particles and RLPc levels.

Increasing long-chain n-3PUFA consumption improves small peripheral artery function in patients at intermediate–high cardiovascular risk

Dietary long-chain n-3 polyunsaturated fatty acids (LCn-3PUFA) improve endothelial function in medium-large-sized arteries, but effects on small peripheral arteries, responsible for most arterial resistance, are little known. We investigated the effects of increasing LCn-3PUFA intake with the usual diet on small artery reactive hyperemia index (saRHI). Within a clinical trial evaluating the effects of 1 year of intensive lifestyle intervention versus standard care on cardiovascular markers in subjects at risk, we selected 108 participants regardless of treatment allocation (n=47 standard care; n=61 intensive intervention) with complete baseline and follow-up information on dietary, clinical, saRHI and biochemical data, including biomarkers of inflammation and endothelial activation. At the end of follow-up, saRHI increased across tertiles of change in dietary LCn-3PUFA. Subjects in the top tertile (increased LCn-3PUFA intake) increased serum ApoA1 and decreased hs-CRP, serum TNF-α, sICAM-1, sVCAM-1 and oxLDL from baseline. After pooling data, in unadjusted models, changes in saRHI significantly correlated to changes in LCn-3PUFA intake and ApoA1 (directly) and changes in systolic blood pressure, waist circumference, TNF-α, sVCAM-1 and sE-selectin (inversely). In a multivariate model, changes in dietary LCn-3PUFA were significantly associated with changes in saRHI [B=0.08 (95% confidence interval=0.083-0.291) for an increase by 100 mg/day]. Systolic blood pressure was inversely associated with saRHI changes [B=-0.203 (-0.441 to -0.029) for a 9-mmHg increase]. We conclude that increased dietary consumption of LCn-3PUFA might be a cost-effective strategy to improve peripheral vasoactivity.

Prevalence of atherogenic dyslipidemia in primary care patients at moderate-very high risk of cardiovascular disease. Cardiovascular risk perception

INTRODUCTION Atherogenic dyslipidemia is an important risk factor for cardiovascular disease. We aim to determine atherogenic dyslipidemia prevalence in primary care patients at moderate-very high cardiovascular risk and its associated cardiovascular risk perception in Spain. METHODS This cross-sectional study included 1137 primary care patients. Patients had previous cardiovascular disease, diabetes mellitus, SCORE risk ≥ 3, severe hypertension or dyslipidemia. Atherogenic dyslipidemia was defined as low HDL-C (<40 mg/dL [males], <50 mg/dL [females]) and elevated triglycerides (≥ 150 mg/dL). A visual analog scale was used to define a perceived cardiovascular disease risk score. RESULTS Mean age was 63.9 ± 9.7 years (64.6% males). The mean BMI was 29.1 ± 4.3 kg/m(2), and mean waist circumference 104.2 ± 12.7 cm (males), and 97.2 ± 14.0 cm (females). 29.4% were smokers, 76.4% had hypertension, 48.0% were diabetics, 24.7% had previous myocardial infarction, and 17.8% peripheral arterial disease. European guidelines classified 83.6% at very high cardiovascular risk. Recommended HDL-C levels were achieved by 50.1% of patients and 37.3% had triglycerides in the reference range. Target LDL-C was achieved by 8.8%. The overall atherogenic dyslipidemia prevalence was 27.1% (34.1% in diabetics). This prevalence in patients achieving target LDL-C was 21.4%. Cardiovascular risk perceived by patients was 4.3/10, while primary care physicians scored 5.7/10. CONCLUSIONS When LDL-C levels are controlled, atherogenic dyslipidemia is more prevalent in those patients at highest cardiovascular risk and with diabetes. This highlights the importance of intervention strategies to prevent the residual vascular risk in this population. Both patients and physicians underestimated cardiovascular risk.

Negative effect of a low-carbohydrate, high-protein, high-fat diet on small peripheral artery reactivity in patients with increased cardiovascular risk

Low-carbohydrate diets have become increasingly popular for weight loss. Although they may improve some metabolic markers, particularly in type 2 diabetes mellitus (T2D) or the metabolic syndrome (MS), their net effect on arterial wall function remains unclear. The objective was to evaluate the relation between dietary macronutrient composition and the small artery reactive hyperaemia index (saRHI), a marker of small artery endothelial function, in a cohort of patients at increased cardiovascular (CV) risk. The present cross-sectional study included 247 patients. Diet was evaluated by a 3-d food-intake register and reduced to a novel low-carbohydrate diet score (LCDS). Physical examination, demographic, biochemical and anthropometry parameters were recorded, and the saRHI was measured in each patient. Individuals in the lowest LCDS quartile (Q1, 45 % carbohydrate; 20 % protein; 32 % fat) had higher saRHI values than those in the top quartile (Q4, 29 % carbohydrate, 24 % protein, 40 % fat; 1.66 (sd 0.41) v. 1.52 (sd 0.22), P= 0.037). These results were particularly strong in patients with the MS (Q1 = 1.82 (sd 0.32) v. Q4 = 1.61 (sd 027); P= 0.021) and T2D (Q1 = 1.78 (sd 0.31) v. Q4 = 1.62 (sd 0.35); P= 0.011). Multivariate analysis demonstrated that individuals in the highest LCDS quartile had a significantly negative coefficient of saRHI, which was independent of confounders (OR -0.85; 95 % CI 0.19, 0.92; P= 0.031). These findings suggest that a dietary pattern characterised by a low amount of carbohydrate, but high amounts of protein and fat, is associated with a poorer small artery vascular reactivity in patients with increased CV risk.

Even low physical activity levels improve vascular function in overweight and obese postmenopausal women.

Objective Some individuals with cardiovascular risk are unable to achieve even the lower internationally recommended level of physical activity (PA). We aimed to study the impact of a lower-than-advised level of PA on small artery vascular function and oxidative stress in overweight and obese postmenopausal women. Methods Forty-seven overweight and obese postmenopausal women completed a 4-month program of 1-hour low-intensity PA for 2 days per week. Before and after the intervention, PA level (metabolic equivalent tasks/h/wk), endogenous antioxidant status (superoxide dismutase and erythrocyte lysate and glutathione peroxidase erythrocyte lysate concentrations, superoxide dismutase plasma and glutathione peroxidase plasma [GPXa] activities, and oxidized low-density lipoprotein), asymmetrical dimethylarginine concentrations, endothelial function by small artery reactive hyperemia index (saRHI), and resting heart rate (RHR) were assessed. Results After the intervention, a significant increase in GPXa and decreases in asymmetrical dimethylarginine concentrations and RHR (P < 0.001 for all) were observed. Increases in PA were positively associated with increases in saRHI (r = 0.330, P = 0.027) and GPXa (r = 0.299, P = 0.05) and a decrease in RHR (r = −0.297, P = 0.047). Multivariate analyses showed that the independent predictors of saRHI improvement were an increase in PA (&bgr; = 2.63; 95% CI, 1.24-4.19; P = 0.019), a decrease in RHR (&bgr; = 1.96; 95% CI, 1.01-5.03; P = 0.048), and an increase in GPXa (&bgr; = 2.64; 95% CI, 1.18-5.08; P = 0.021). Conclusions Even low-intensity PA improves antioxidant capacity, RHR, and saRHI in postmenopausal women. Advising postmenopausal women to increase their PA at any level seems warranted based on our preliminary and hypothesis-generating data.

Role of the fatty acid-binding protein 4 in heart failure and cardiovascular disease

Obesity and ectopic fat accumulation in non-adipose tissues are major contributors to heart failure (HF) and cardiovascular disease (CVD). Adipocytes act as endocrine organs by releasing a large number of bioactive molecules into the bloodstream, which participate in a communication network between white adipose tissue and other organs, including the heart. Among these molecules, fatty acid-binding protein 4 (FABP4) has recently been shown to increase cardiometabolic risk. Both clinical and experimental evidence have identified FABP4 as a relevant player in atherosclerosis and coronary artery disease, and it has been directly related to cardiac alterations such as left ventricular hypertrophy (LVH) and both systolic and diastolic cardiac dysfunction. The available interventional studies preclude the establishment of a direct causal role of this molecule in CVD and HF and propose FABP4 as a biomarker rather than as an aetiological factor. However, several experimental reports have suggested that FABP4 may act as a direct contributor to cardiac metabolism and physiopathology, and the pharmacological targeting of FABP4 may restore some of the metabolic alterations that are conducive to CVD and HF. Here, we review the current knowledge regarding FABP4 in the context of HF and CVD as well as the molecular basis by which this protein participates in the regulation of cardiac function.

Clinical and pathophysiological evidence supporting the safety of extremely low LDL levels—The zero-LDL hypothesis

While the impact of very low concentrations of low-density lipoprotein cholesterol (LDL-C) on cardiovascular prevention is very reassuring, it is intriguing to know what effect these extremely low LDL-C concentrations have on lipid homoeostasis. The evidence supporting the safety of extremely low LDL levels comes from genetic studies and clinical drug trials. Individuals with lifelong low LDL levels due to mutations in genes associated with increased LDL-LDL receptor (LDLR) activity reveal no safety issues. Patients achieving extremely low LDL levels in the IMPROVE-IT and FOURIER, and the PROFICIO and ODYSSEY programs seem not to have an increased prevalence of adverse effects. The main concern regarding extremely low LDL-C plasma concentrations is the adequacy of the supply of cholesterol, and other molecules, to peripheral tissues. However, LDL proteomic and kinetic studies reaffirm that LDL is the final product of endogenous lipoprotein metabolism. Four of 5 LDL particles are cleared through the LDL-LDLR pathway in the liver. Given that mammalian cells have no enzymatic systems to degrade cholesterol, the LDL-LDLR pathway is the main mechanism for removal of cholesterol from the body. Our focus, therefore, is to review, from a physiological perspective, why such extremely low LDL-C concentrations do not appear to be detrimental. We suggest that extremely low LDL-C levels due to increased LDLR activity may be a surrogate of adequate LDL-LDLR pathway function.

APOA5 genetic and epigenetic variability jointly regulate circulating triacylglycerol levels.

Apolipoprotein A5 gene (APOA5) variability explains part of the individuals predisposition to hypertriacylglycerolaemia (HTG). Such predisposition has an inherited component (polymorphisms) and an acquired component regulated by the environment (epigenetic modifications). We hypothesize that the integrated analysis of both components will improve our capacity to estimate APOA5 contribution to HTG. We followed a recruit-by-genotype strategy to study a population composed of 44 individuals with high cardiovascular disease risk selected as being carriers of at least one APOA5 SNP (-1131T>C and/or, S19W and/or 724C>G) compared against 34 individuals wild-type (WT) for these SNPs. DNA methylation patterns of three APOA5 regions [promoter, exon 2 and CpG island (CGI) in exon 3] were evaluated using pyrosequencing technology. Carriers of APOA5 SNPs had an average of 57.5% higher circulating triacylglycerol (TG) levels (P=0.039). APOA5 promoter and exon 3 were hypermethylated whereas exon 2 was hypomethylated. Exon 3 methylation positively correlated with TG concentration (r=0.359, P=0.003) and with a lipoprotein profile associated with atherogenic dyslipidaemia. The highest TG concentrations were found in carriers of at least one SNP and with a methylation percentage in exon 3 ≥82% (P=0.009). In conclusion, CGI methylation in exon 3 of APOA5 acts, in combination with -1131T>C, S19W and 724C>G polymorphisms, in the individuals predisposition to high circulating TG levels. This serves as an example that combined analysis of SNPs and methylation applied to a larger set of genes would improve our understanding of predisposition to HTG.

Hipercolesterolemia familiar en la infancia y la adolescencia: una realidad oculta

Familial hypercholesterolemia (FH) is the most common genetic disorder in childhood, but in most cases is not detected. High levels of low-density lipoprotein cholesterol are present since the childs birth and this fact will suppose silent development of early atherosclerosis. In cases of homozygous FH, the coronary disease will appear before 20s and in cases of heterozygous FH will occur in middle age. Despite published data, there is not agreement about how and when perform the screening. Familial history of early cardiovascular disease plus presence of hypercholesterolemia in parents is crucial for detection and diagnosis. Actually, it is topic of discussion that it is necessary to achieve therapeutic goals from an early age to improve prognosis. Lifestyle changes are the first line therapy. Statins are the lipid-lowering drugs of choice but the optimal age to start therapy it is still controversial. In this article, current recommendations of expert consensus guidelines about the management and new line therapies of child and adolescents are reviewed.