Molecular basis of familial hypercholesterolemia

Purpose of review To provide an overview about the molecular basis of familial hypercholesterolemia. Recent findings Familial hypercholesterolemia is a common hereditary cause of premature coronary heart disease. It has been estimated that 1 in every 250 individuals has heterozygous familial hypercholesterolemia and that fewer than 1% of patients with familial hypercholesterolemia have been identified across the globe. If heterozygous familial hypercholesterolemia is left untreated, it is likely that coronary heart disease will manifest clinically prior to the age of 55 years and that half of all patients will prematurely die from the consequences of myocardial infarction. It is crucial to understand the molecular basis of familial hypercholesterolemia to diagnose familial hypercholesterolemia properly. Summary The phenotype of familial hypercholesterolemia is caused by more than 1700 mutations the LDLR, apoB and PCSK9 genes, which explains approximately 85% of familial hypercholesterolemia cases. By means of next-generation sequencing, an increasing number of mutations in established and putative novel genes associated with this phenotype have been identifie

New Drugs for Atherosclerosis

Atherosclerosis, the underlying process that ultimately leads to clinical cardiovascular disease (CVD), is caused by the multifactorial interaction of various conditions, and dyslipidemia is widely acknowledged as 1 of the crucial risk factors in this process. Statin drugs have been shown to decrease low-density lipoprotein cholesterol and CVD morbidity as well as mortality and are therefore pivotal in CVD prevention. Despite the use of statin drugs, CVD remains a leading cause of mortality worldwide, which suggests that additional lipid-lowering therapies are warranted. Several novel therapeutic agents, which are described in this review, are now well on their way in their respective development paths and might revolutionize anti-atherosclerotic drug therap

The identification and function of a Netrin-1 mutation in a pedigree with premature atherosclerosis

Background and aims: Neuroimmune guidance cues have been shown to play a role in atherosclerosis, but their exact role in human pathophysiology is largely unknown. In the current study, we investigated the role of a c.1769G > T variant in Netrin-1 in (premature) atherosclerosis. Methods: To determine the effect of the genetic variation, purified Netrin-1, either wild type (wtNetrin-1) or the patient observed variation (mutNetrin-1), was used for migration, adhesion, endothelial barrier function and bindings assays. Expression of adhesion molecules and transcription proteins was analyzed by RT-PCR, Western blot or ELISA. To further delineate how mutNetrin-1 mediates its effect on cell migration, lenti-viral knockdown of UNC5B or DCC was used. Results: Bindings assays revealed a decreased binding capacity of mutNetrin-1 to the receptors UNC5B, DCC and β3-integrin and an increased binding capacity to neogenin, heparin and heparan sulfate compared to wtNetrin-1. Exposure of endothelial cells to mutNetrin-1 resulted in enhanced monocyte adhesion and expression of IL-6, CCL2 and ICAM-1 compared to wtNetrin-1. In addition, mutNetrin-1 lacks the inhibitory effect on the NF-κB pathway that is observed for wtNetrin-1. Moreover, the presence of mutNetrin-1 diminished migration of macrophages and smooth muscle cells. Importantly, UNC5B or DCC specific knockdown showed that mutNetrin-1 is unable to act through DCC resulting in enhanced inhibition of migration. Conclusions: Our data demonstrates that mutNetrin-1 fails to exert anti-inflammatory effects on endothelial cells and more strongly blocks macrophage migration compared to wtNetrin-1, suggesting that the carriers of this genetic molecular variant may well be at risk for premature atherosclerosis

Netrin-1 and the Grade of Atherosclerosis Are Inversely Correlated in Humans

OBJECTIVE: Netrin-1 has been shown to play a role in the initiation of atherosclerosis in mice models. However, little is known about the role of Netrin-1 in humans. We set out to study whether Netrin-1 is associated with different stages of atherosclerosis. Approach and Results: Plasma Netrin-1 levels were measured in different patient cohorts: (1) 22 patients with high cardiovascular risk who underwent arterial wall inflammation assessment using positron-emission tomography / computed tomography, (2) 168 patients with a positive family history of premature atherosclerosis in whom coronary artery calcium scores were obtained, and (3) 104 patients with chest pain who underwent coronary computed tomography angiography imaging to evaluate plaque vulnerability and burden. Netrin-1 plasma levels were negatively correlated with arterial wall inflammation (β, -0.01 [95% CI, 0.02 to -0.01] R2, 0.61; P<0.0001), and concentrations of Netrin-1 were significantly lower when atherosclerosis was present compared with individuals without atherosclerosis (28.01 versus 10.51 ng/mL, P<0.001). There was no difference in Netrin-1 plasma concentrations between patients with stable versus unstable plaques (11.17 versus 11.74 ng/mL, P=0.511). However, Netrin-1 plasma levels were negatively correlated to total plaque volume (β, -0.09 [95% CI, -0.11 to -0.08] R2, 0.57, P<0.0001), calcified plaque volumes (β, -0.10 [95% CI, -0.12 to -0.08] R2, 0.53; P<0.0001), and noncalcified plaque volumes (β, -0.08 [95% CI, -0.10 to -0.06] R2, 0.41; P<0.0001). Treatment of inflammatory stimulated endothelial cells with plasma with high Netrin-1 level resulted in reduced endothelial inflammation and consequently, less monocyte adhesion. CONCLUSIONS: Netrin-1 plasma levels are lower in patients with subclinical atherosclerosis and in patients with arterial wall inflammation. Netrin-1 is not associated with plaque vulnerability; however, it is negatively correlated to plaque burden, suggesting that Netrin-1 is involved in some, but not all, stages of atherosclerosis

Genetic variants in SUSD2 are associated with the risk of ischemic heart disease

Background: Genetic factors partly determine the risk for premature myocardial infarction (MI). Objectives: We report the identification of a novel rare genetic variant in a kindred with an autosomal dominant trait for premature MI and atherosclerosis and explored the association of a common nonsynonymous variant in the same gene with the risk of ischemic heart disease (IHD) in a population-based study. Methods: Next-generation sequencing was performed in a small pedigree with premature MI or subclinical atherosclerosis. A common variant, rs8141797 A>G (p.Asn466Ser), in sushi domain–containing protein 2 (SUSD2) was studied in the prospective Copenhagen General Population Studies (N = 105,408) for association with IHD. Results: A novel heterozygous nonsense mutation in SUSD2 (c.G583T; p.Glu195Ter) was associated with the disease phenotype in the pedigree. SUSD2 protein was expressed in aortic specimens in the subendothelial cell layer and around the vasa vasorum. Furthermore, the minor G-allele of rs8141797 was associated with per allele higher levels of SUSD2 mRNA expression in the heart and vasculature. In the Copenhagen General Population Study, hazard ratios for IHD were 0.92 (95% CI: 0.87–0.97) in AG heterozygotes and 0.86 (0.62–1.19) in GG homozygotes vs noncarrriers (P-trend =.002). Finally, in meta-analysis including 73,983 IHD cases and 215,730 controls, the odds ratio for IHD per G-allele vs A-allele was 0.93 (0.90–0.96) (P = 4.6 × 10−7). Conclusions: The identification of a truncating mutation in SUSD2, which was associated with premature MI and subclinical atherosclerosis, combined with the finding that a common missense variant in SUSD2 was strongly associated with a lower risk of IHD, suggest that SUSD2 may alter the risk of atherosclerosis

Genetic variants in <i>SUSD2</i> are associated with the risk of ischemic heart disease

Background: Genetic factors partly determine the risk for premature myocardial infarction (MI). Objectives: We report the identification of a novel rare genetic variant in a kindred with an autosomal dominant trait for premature MI and atherosclerosis and explored the association of a common nonsynonymous variant in the same gene with the risk of ischemic heart disease (IHD) in a population-based study. Methods: Next-generation sequencing was performed in a small pedigree with premature MI or subclinical atherosclerosis. A common variant, rs8141797 A>G (p.Asn466Ser), in sushi domain–containing protein 2 (SUSD2) was studied in the prospective Copenhagen General Population Studies (N = 105,408) for association with IHD. Results: A novel heterozygous nonsense mutation in SUSD2 (c.G583T; p.Glu195Ter) was associated with the disease phenotype in the pedigree. SUSD2 protein was expressed in aortic specimens in the subendothelial cell layer and around the vasa vasorum. Furthermore, the minor G-allele of rs8141797 was associated with per allele higher levels of SUSD2 mRNA expression in the heart and vasculature. In the Copenhagen General Population Study, hazard ratios for IHD were 0.92 (95% CI: 0.87–0.97) in AG heterozygotes and 0.86 (0.62–1.19) in GG homozygotes vs noncarrriers (P-trend =.002). Finally, in meta-analysis including 73,983 IHD cases and 215,730 controls, the odds ratio for IHD per G-allele vs A-allele was 0.93 (0.90–0.96) (P = 4.6 × 10−7). Conclusions: The identification of a truncating mutation in SUSD2, which was associated with premature MI and subclinical atherosclerosis, combined with the finding that a common missense variant in SUSD2 was strongly associated with a lower risk of IHD, suggest that SUSD2 may alter the risk of atherosclerosis