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Aims The adenylate cyclase type 9 (ADCY9) gene appears to determine atherosclerotic outcomes in patients treated with dalcetrapib. In mice, we recently demonstrated that Adcy9 inactivation potentiates endothelial function and inhibits atherogenesis. The objective of this study was to characterize the contribution of ADCY9 to the regulation of endothelial signalling pathways involved in atherosclerosis. Methods and results We show that ADCY9 is expressed in the endothelium of mouse aorta and femoral arteries. We demonstrate that ADCY9 inactivation in cultured endothelial cells paradoxically increases cAMP accumulation in response to the adenylate cyclase activators forskolin and vasoactive intestinal peptide (VIP). Reciprocally, ADCY9 overexpression decreases cAMP production. Using mouse femoral artery arteriography, we show that Adcy9 inactivation potentiates VIP-induced endothelial-dependent vasodilation. Moreover, Adcy9 inactivation reduces mouse atheroma endothelial permeability in different vascular beds. ADCY9 overexpression reduces forskolin-induced phosphorylation of Ser157-vasodilator-stimulated phosphoprotein (VASP) and worsens thrombin-induced fall of RAP1 activity, both leading to increased endothelial permeability. ADCY9 inactivation in thrombin-stimulated human coronary artery endothelial cells results in cAMP accumulation, increases p-Ser157-VASP, and inhibits endothelial permeability. MLC2 phosphorylation and actin stress fibre increases in response to thrombin were reduced by ADCY9 inactivation, suggesting actin cytoskeleton regulation. Finally, using the Miles assay, we demonstrate that Adcy9 regulates thrombin-induced endothelial permeability in vivo in normal and atherosclerotic animals. Conclusion Adcy9 is expressed in endothelial cells and regulates local cAMP and endothelial functions including permeability relevant to atherogenesis.

Background: 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. Methods: Adcy9 -inactivated ( Adcy9 Gt/Gt ) and wild-type (WT) mice, that were or not transgenic for the CETP gene (CETPtg Adcy9 Gt/Gt and CETPtg Adcy9 WT ), were submitted to an atherogenic protocol (injection of an AAV8 [adeno-associated virus serotype 8] expressing a PCSK9 [proprotein convertase subtilisin/kexin type 9] gain-of-function variant and 0.75% cholesterol diet for 16 weeks). Atherosclerosis, vasorelaxation, telemetry, and adipose tissue magnetic resonance imaging were evaluated. Results: Adcy9 Gt/Gt mice had a 65% reduction in aortic atherosclerosis compared to WT ( P Adcy9 Gt/Gt mice compared to WT animals ( P Adcy9 Gt/Gt mice (versus WT, P Adcy9 Gt/Gt ( P Adcy9 Gt/Gt mice allowed significantly less adhesion of splenocytes compared to WT ( P Adcy9 Gt/Gt mice gained more weight than WT with the atherogenic diet; this was associated with an increase in whole body adipose tissue volume ( P Adcy9 Gt/Gt compared to WT mice ( P P P =0.0572). Adcy9 inactivation–induced effects on atherosclerosis, endothelial function, weight gain, adipose tissue volume, and feed efficiency were lost in CETPtg Adcy9 Gt/Gt mice ( P >0.05 versus CETPtg Adcy9 WT ). Conclusions: 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.

Adiponectin is an adipokine whose plasma levels are inversely correlated to metabolic syndrome components. Adiponectin protects against atherosclerosis and decreases risks in myocardial infarction. Endothelial progenitor cells (EPCs) are a heterogeneous population of circulating cells involved in vascular repair and neovascularization. EPCs number is reduced in patients with cardiovascular disease. We hypothesize that the positive effects of adiponectin against atherosclerosis are explained in part by its interactions with EPCs. Cells were obtained from healthy volunteers' blood by mononuclear cell isolation and plating on collagen-coated dishes. Three sub-populations of EPCs were identified and characterized using flow cytometry. EPCs' expression of adiponectin receptors, AdipoR1, and AdipoR2 was evaluated by quantitative PCR. The effects of recombinant adiponectin on EPCs' susceptibility to apoptosis were assessed. Finally, expression of neutrophil elastase by EPCs and activity of this enzyme on adiponectin processing were assessed. Quantitative PCR analysis of EPCs mRNAs showed that AdipoR1 mRNA is expressed at higher levels than AdipoR2. Expression of AdipoR1 protein was confirmed by western blot. Adiponectin significantly increased survival of two sub-populations of EPCs in conditions of serum deprivation. Such effect could not be demonstrated in the third EPCs sub-population. We also demonstrated that EPCs, particularly one sub-population, express neutrophil elastase. Neutrophil elastase activity was confirmed in EPCs' conditioned media. Adiponectin protects some EPCs sub-populations against apoptosis and therefore could modulate EPCs ability to induce repair of vascular damage. Neutrophil elastase activity of EPCs could locally modulate adiponectin activity by its involvement in the generation of the globular form of adiponectin.

Objective— 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. Approach and Results— 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. Conclusions— 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.

Background: Studies have shown that low HDL-cholesterol levels may be associated with the progression of aortic valvular calcium and aortic valvular stenosis (AVS), but whether patients with AVS have impaired cholesterol efflux capacities is unknown. Methods and results: We have measured four parameters of cholesterol efflux capacity in apolipoprotein B-depleted serum samples from 48 patients with (aortic jet velocity ≥2.5 m/s, mean age = 72 ± 7 years and 72.7% men) and 51 patients without AVS (aortic jet velocity ≤ 1.7 m/s, mean age 71 ± 7 years and 70.6% men). Cholesterol efflux capacity was measured using J774 macrophages with and without stimulation of ABCA1 expression by cAMP (non-stimulated efflux, total efflux and ABCA1-mediated efflux), and HepG2 hepatocytes to measure SR-BI-mediated efflux. Mean HDL-cholesterol and apolipoprotein A-I levels as well as efflux are shown in the table for patients with vs. without AVS. The Pearson correlation coefficient between HDL-cholesterol levels and SR-B1-dependent efflux was 0.39 (p=0.007) in patients with AVS and 0.68 ( Conclusions: This study provides evidence that serum from patients with AVS may have impaired cholesterol efflux capacities, especially through the SR-B1 pathway. Table. Mean HDL-cholesterol and apolipoprotein A-I levels as well as non-stimulated-, total-, ABCA1-, and SR-B1-dependent cholesterol efflux obtained from patients’ serum with vs. without AVS. Data is shown as mean ± SD. Differences between categories were assessed using a Student unpaired t-test.