👤 David Rhainds

The metabolic environment plays a crucial role in the development of heart failure (HF). Our prior research demonstrated that myo-inositol, a metabolite transported by the sodium-myo-inositol co-transporter 1 (SMIT-1), can induce oxidative stress and may be detrimental to heart function. However, plasmatic myo-inositol concentration has not been comprehensively assessed in large cohorts of patients with heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF). Plasmatic myo-inositol levels were measured using mass spectrometry and correlated with clinical characteristics in no HF subjects and patients with HFrEF and HFpEF from Belgian (male, no HF, 53%; HFrEF, 84% and HFpEF, 40%) and Canadian cohorts (male, no HF, 51%; HFrEF, 92% and HFpEF, 62%). Myo-inositol levels were significantly elevated in patients with HF, with a more pronounced increase observed in the HFpEF population of both cohorts. After adjusting for age, sex, body mass index, hypertension, diabetes, and atrial fibrillation, we observed that both HFpEF status and impaired kidney function were associated with elevated plasma myo-inositol. Unlike HFrEF, abnormally high myo-inositol (≥69.8 μM) was linked to unfavourable clinical outcomes (hazard ratio, 1.62; 95% confidence interval, [1.05-2.5]) in patients with HFpEF. These elevated levels were correlated with NTproBNP, troponin, and cardiac fibrosis in this subset of patients. Myo-inositol is a metabolite elevated in patients with HF and strongly correlated to kidney failure. In patients with HFpEF, high myo-inositol levels predict poor clinical outcomes and are linked to markers of cardiac adverse remodelling. This suggests that myo-inositol and its transporter SMIT1 may have a role in the pathophysiology of HFpEF. BECAME-HF was supported by Collaborative Bilateral Research Program Québec - Wallonie-Brussels Federation. Show less

Genetic variants in drug targets can be used to predict the long-term, on-target effect of drugs. Here, we extend this principle to assess how sex and body mass index may modify the effect of genetically predicted lower CETP levels on biomarkers and cardiovascular outcomes. We found sex and body mass index (BMI) to be modifiers of the association between genetically predicted lower CETP and lipid biomarkers in UK Biobank participants. Female sex and lower BMI were associated with higher high-density lipoprotein cholesterol and lower low-density lipoprotein cholesterol for the same genetically predicted reduction in CETP concentration. We found that sex also modulated the effect of genetically lower CETP on cholesterol efflux capacity in samples from the Montreal Heart Institute Biobank. However, these modifying effects did not extend to sex differences in cardiovascular outcomes in our data. Our results provide insight into the clinical effects of CETP inhibitors in the presence of effect modification based on genetic data. The approach can support precision medicine applications and help assess the external validity of clinical trials. Show less

The large HDL particles generated by administration of cholesteryl ester transfer protein inhibitors (CETPi) remain poorly characterized, despite their potential importance in the routing of cholesterol to the liver for excretion, which is the last step of the reverse cholesterol transport. Thus, the effects of the CETPi dalcetrapib and anacetrapib on HDL particle composition were studied in rabbits and humans. The association of rabbit HDL to the LDL receptor (LDLr) in vitro was also evaluated. New Zealand White rabbits receiving atorvastatin were treated with dalcetrapib or anacetrapib. A subset of patients from the dal-PLAQUE-2 study treated with dalcetrapib or placebo were also studied. In rabbits, dalcetrapib and anacetrapib increased HDL-C by more than 58% (P < 0.01) and in turn raised large apo E-containing HDL by 66% (P < 0.001) and 59% (P < 0.01), respectively. Additionally, HDL from CETPi-treated rabbits competed with human LDL for binding to the LDLr on HepG2 cells more than control HDL (P < 0.01). In humans, dalcetrapib increased concentrations of large HDL particles (+69%, P < 0.001) and apo B-depleted plasma apo E (+24%, P < 0.001), leading to the formation of apo E-containing HDL (+47%, P < 0.001) devoid of apo A-I. Overall, in rabbits and humans, CETPi increased large apo E-containing HDL particle concentration, which can interact with hepatic LDLr. The catabolism of these particles may depend on an adequate level of LDLr to contribute to reverse cholesterol transport. Show less

The validity of HDL-cholesterol (HDL-C) elevation as a therapeutic target has been questioned, in comparison to enhancing HDL functionality. Cholesterol efflux capacity (CEC) is an in-vitro assay that measures the ability of an individual's HDL to promote cholesterol efflux from cholesterol donor cells such as macrophages. CEC of HDL is a predictor of cardiovascular risk independent of HDL-C levels. However, molecular determinants of CEC and the effects of diseases and therapeutic interventions on CEC have not been completely defined. We review here recent findings on elevated HDL-C and disease risk, as well as determinants of CEC, from genetics and proteomics to pathophysiology and therapeutic interventions that contribute to our understanding of CEC as a biomarker of HDL functionality. Elevated HDL-C levels are not always protective against cardiovascular disease and mortality. CEC is a heritable trait, and genetic polymorphisms in genes involved in HDL and triglycerides metabolism are associated with CEC. Multiple HDL proteins correlate positively with CEC levels and inversely with noncalcified plaque burden. Differences in CEC assays that make comparisons between studies difficult are also emphasized. CEC should be measured in clinical trials of lipid-modifying and anti-inflammatory therapies to determine whether increases are cardioprotective. Show less

Background Macrophage cholesterol efflux to high-density lipoproteins ( HDLs ) is the first step of reverse cholesterol transport. The cholesterol efflux capacity ( CEC ) of HDL particles is a protective risk factor for coronary artery disease independent of HDL cholesterol levels. Using a genome-wide association study approach, we aimed to identify pathways that regulate CEC in humans. Methods and Results We measured CEC in 5293 French Canadians. We tested the genetic association between 4 CEC measures and genotypes at >9 million common autosomal DNA sequence variants. These analyses yielded 10 genome-wide significant signals ( P<6.25×10 Show less

Pharmacogenomic studies have shown that ADCY9 genotype determines the effects of the CETP (cholesteryl ester transfer protein) inhibitor dalcetrapib on cardiovascular events and atherosclerosis imaging. The underlying mechanisms responsible for the interactions between ADCY9 and CETP activity have not yet been determined. Adcy9-inactivated ( Adcy9 Adcy9 Adcy9 inactivation protects against atherosclerosis, but only in the absence of CETP activity. This atheroprotection may be explained by decreased macrophage accumulation and proliferation in the arterial wall, and improved endothelial function and autonomic tone. Show less

Inhibition of cholesteryl ester transfer protein (CETP) increases HDL cholesterol (HDL-C) levels. However, the circulating CETP level varies and the impact of its inhibition in species with high CETP levels on HDL structure and function remains poorly characterized. This study investigated the effects of dalcetrapib and anacetrapib, the two CETP inhibitors (CETPis) currently being tested in large clinical outcome trials, on HDL particle subclass distribution and cholesterol efflux capacity of serum in rabbits and monkeys. New Zealand White rabbits and vervet monkeys received dalcetrapib and anacetrapib. In rabbits, CETPis increased HDL-C, raised small and large α-migrating HDL, and increased ABCA1-induced cholesterol efflux. In vervet monkeys, although anacetrapib produced similar results, dalcetrapib caused opposite effects because the LDL-C level was increased by 42% and HDL-C decreased by 48% ( Show less

High-density lipoproteins are involved in reverse cholesterol transport and possess anti-inflammatory and antioxidative properties. Paradoxically, CETP (cholesteryl ester transfer protein) inhibitors have been shown to increase inflammation as revealed by a raised plasma level of high-sensitivity C-reactive protein. CETP inhibitors did not improve clinical outcomes in large-scale clinical trials of unselected patients with coronary disease. Dalcetrapib is a CETP modulator for which effects on cardiovascular outcomes were demonstrated in the dal-OUTCOMES trial to be influenced by correlated polymorphisms in the Show less

Studies have shown that high-density lipoprotein (HDL)-raising compounds induce regression of aortic valve stenosis (AVS) in animal models. However, whether patients with AVS have an impaired HDL metabolism is unknown. A total of 1435 single nucleotide polymorphisms in genes associated with HDL cholesterol levels (in or around GALNT2, LPL, ABCA1, APOA5, SCARB1, LIPC, CETP, LCAT, LIPG, APOC4, and PLTP) were genotyped in 382 patients with echocardiography-confirmed AVS (aortic jet velocity ≥2.5 m/s) and 401 controls. After control for multiple testing, none of the genetic variants showed a positive association with case/control status (adjusted P≥0.05 for all single nucleotide polymorphisms tested). In a subsample of this cohort, HDL cholesterol levels, apolipoprotein AI levels, lecithin-cholesterol acyltransferase activity, pre-β-HDL, HDL size, and 4 parameters of cholesterol efflux capacity were measured in apolipoprotein B-depleted serum samples from 86 patients with and 86 patients without AVS. Cholesterol efflux capacity was measured using J774 macrophages with and without stimulation of ATP-binding cassette A-1 expression by cAMP, and HepG2 hepatocytes for scavenger receptor class B type 1-mediated efflux. None of these parameters were different between cases and controls. However, compared with patients without coronary artery disease, sera from patients with coronary artery disease had lower HDL cholesterol levels, scavenger receptor class B type 1-mediated efflux, and HDL size (P≤0.003), independently of the presence or absence of AVS. Results of the present study suggest that, based on HDL genetics and HDL functionality, HDL metabolism does not seem to predict the risk of AVS. Because of our limited sample size, additional studies are needed to confirm these findings. Show less

The CD36 selective ligand, EP 80317, features potent anti-atherosclerotic and hypocholesterolemic effects that are associated with an increase in macrophage cholesterol efflux through the activation of the peroxisome proliferator-activated receptor γ-liver X receptor α (LXRα)-ATP-binding cassette (ABC) transporter pathway. Cholesterol efflux is the first step of reverse cholesterol transport (RCT). However, whether EP 80317 exerts its hypocholesterolemic and anti-atherosclerotic activity through RCT in vivo has yet to be determined. In the present study, we investigated the effects of EP 80317 on RCT, in particular on macrophage-to-feces RCT and the expression of selected genes associated with hepatic cholesterol metabolism and intestinal cholesterol transport. Reverse cholesterol transport was assessed following the intraperitoneal injection of [(3)H]-cholesterol-labelled J774 macrophages to hypercholesterolemic apoE- and apoE/CD36 double-deficient mice that had been treated for 12 weeks with EP 80317. Forty-eight hours after the administration of [(3)H]-cholesterol-labelled cells, blood, liver, intestines and feces were harvested. The radioactivity recovered in the feces (cholesterol and bile acid combined) was significantly increased by 311% (P = 0.0259) in EP 80317-treated mice compared with that found in vehicle-treated mice despite no significant change in [(3)H]-tracer recovery in plasma between groups. Whereas the mRNA levels of LXRα in the gut were significantly upregulated, mRNA and protein levels of the Niemann-Pick C1-like 1 protein (NPC1L1) transporter, a LXRα target which regulates intestinal cholesterol absorption, were downregulated in EP 80317-treated mice. In contrast, neither mRNA nor protein levels of investigated transporters and receptors were modulated in the small intestine of double-deficient mice, nor was the fecal recovery of radioactivity. No change was observed in targeted genes in liver of either apoE- or apoE/CD36 double-deficient mice after a chronic treatment with EP 80317. This study shows that EP 80317 elicits macrophage-to-feces reverse cholesterol transport in a manner dependent on CD36 expression. This effect is associated with the upregulation of LXRα and the downregulation of NPC1L1 expression. Show less