Low-density Lipoprotein Cholesterol Metabolism Research Articles

The role of natural products as PCSK9 modulators: A review.

A variety of mechanisms and drugs have been shown to attenuate cardiovascular disease (CVD) onset and/or progression. Recent researchers have identified a potential role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in modulating lipid metabolism and reducing plasma low density lipoprotein (LDL) levels. PCSK9 is the central protein in the metabolism of LDL cholesterol (LDL-C) owing to its major function in LDL receptor (LDLR) degradation. Due to the close correlation of cardiovascular disease with lipid levels, many in vivo and in vitro investigations are currently underway studying the physiological role of PCSK9. Furthermore, many studies are actively investigating the mechanisms of various compounds that influence lipid associated-disorders and their associated cardiovascular diseases. PCSK9 inhibitors have been shown to have significant impact in the prevention of emerging cardiovascular diseases. Natural products can effectively be used as PCSK9 inhibitors to control lipid levels through various mechanisms. In this review, we evaluate the role of phytochemicals and natural products in the regulation of PCSK9, and their ability to prevent cardiovascular diseases. Moreover, we describe their mechanisms of action, which have not to date been delineated.

Unveiling Cardiovascular Connections between Familial Hypercholesterolemia (FH) and Left Ventricular Hypertrophy (LVH)

Left ventricular hypertrophy (LVH), a complex cardiac condition characterized by the enlargement and thickening of the left ventricle, is primarily associated with hypertension and valvular heart disease. Recent studies have identified familial hypercholesterolemia (FH) as a secondary cause of LVH. It is characterized by high low-density lipoprotein cholesterol (LDL-C) in blood. FH is an inherited disorder which involves genetic variations associated with abnormal metabolism of LDL-C. This review article aims to provide a comprehensive overview of the relationship between FH and LVH. It summarizes the current understanding of the pathophysiological mechanisms underlying this association and discusses its implications for clinical practice. Elevated LDL-C levels in FH patients lead to accelerated atherosclerosis and an increased risk of premature cardiovascular events. Animal models and clinical observations provide insights into the mechanistic links between elevated LDL-C levels, oxidative stress, inflammation, and LVH development. Early diagnosis of FH would certainly play a critical role in preventing or delaying the development of LVH and subsequent cardiovascular complications. Preemptive measures emphasize the identification of at risk individuals, in-depth clinical evaluations, and implementation of effective treatments including lifestyle modifications, statins, and adjunctive therapies, such as PCSK9 inhibitors or lipoprotein apheresis. By increasing the awareness of FH as a secondary cause of LVH, healthcare professionals can improve early detection and implement appropriate management strategies to mitigate the cardiovascular burden associated with this inherited disorder.

20( S )-Protopanaxatriol Improves Atherosclerosis by Inhibiting Low-Density Lipoprotein Receptor Degradation in ApoE KO Mice.

Atherosclerosis (AS) is a chronic progressive disease caused by various factors and causes various cerebrovascular and cardiovascular diseases (CVDs). Reducing the plasma levels of low-density lipoprotein cholesterol is the primary goal in preventing and treating AS. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a crucial role in regulating low-density lipoprotein cholesterol metabolism. Panax notoginseng has potent lipid-reducing effects and protects against CVDs, and its saponins induce vascular dilatation, inhibit thrombus formation, and are used in treating CVDs. However, the anti-AS effect of the secondary metabolite, 20( S )-protopanaxatriol (20( S )-PPT), remains unclear. In this study, the anti-AS effect and molecular mechanism of 20( S )-PPT were investigated in vivo and in vitro by Western blotting, real-time polymerase chain reaction, enzyme-linked immunosorbent assay, immunofluorescence staining, and other assays. The in vitro experiments revealed that 20( S )-PPT reduced the levels of PCSK9 in the supernatant of HepG2 cells, upregulated low-density lipoprotein receptor protein levels, promoted low-density lipoprotein uptake by HepG2 cells, and reduced PCSK9 mRNA transcription by upregulating the levels of forkhead box O3 protein and mRNA and decreasing the levels of HNF1α and SREBP2 protein and mRNA. The in vivo experiments revealed that 20( S )-PPT upregulated aortic α-smooth muscle actin expression, increased the stability of atherosclerotic plaques, and reduced aortic plaque formation induced by a high-cholesterol diet in ApoE -/- mice (high-cholesterol diet-fed group). Additionally, 20( S )-PPT reduced the aortic expression of CD68, reduced inflammation in the aortic root, and alleviated the hepatic lesions in the high-cholesterol diet-fed group. The study revealed that 20( S )-PPT inhibited low-density lipoprotein receptor degradation via PCSK9 to alleviate AS.

Post-translational regulation of the low-density lipoprotein receptor provides new targets for cholesterol regulation.

The amount of the low-density lipoprotein receptor (LDLR) on the surface of hepatocytes is the primary determinant of plasma low-density lipoprotein (LDL)-cholesterol level. Although the synthesis and cellular trafficking of the LDLR have been well-documented, there is growing evidence of additional post-translational mechanisms that regulate or fine tune the surface availability of the LDLR, thus modulating its ability to bind and internalise LDL-cholesterol. Proprotein convertase subtilisin/kexin type 9 and the asialoglycoprotein receptor 1 both independently interact with the LDLR and direct it towards the lysosome for degradation. While ubiquitination by the E3 ligase inducible degrader of the LDLR also targets the receptor for lysosomal degradation, ubiquitination of the LDLR by a different E3 ligase, RNF130, redistributes the receptor away from the plasma membrane. The activity of the LDLR is also regulated by proteolysis. Proteolytic cleavage of the transmembrane region of the LDLR by γ-secretase destabilises the receptor, directing it to the lysosome for degradation. Shedding of the extracellular domain of the receptor by membrane-type 1 matrix metalloprotease and cleavage of the receptor in its LDL-binding domain by bone morphogenetic protein-1 reduces the ability of the LDLR to bind and internalise LDL-cholesterol at the cell surface. A better understanding of how the activity of the LDLR is regulated will not only unravel the complex biological mechanisms controlling LDL-cholesterol metabolism but also could help inform the development of alternative pharmacological intervention strategies for the treatment of hypercholesterolaemia.

A virus-like particle-based bivalent PCSK9 vaccine lowers LDL-cholesterol levels in non-human primates

Elevated low-density lipoprotein cholesterol (LDL-C) is an important risk factor in the development of atherosclerotic cardiovascular disease (ASCVD). Inhibitors of proprotein convertase subtilisin/kexin type 9 (PCSK9), a negative regulator of LDL-C metabolism, have emerged as promising approaches for reducing elevated LDL-C levels. Here, we evaluated the cholesterol-lowering efficacy of virus-like particle (VLP) based vaccines that target epitopes found within the LDL receptor (LDL-R) binding domain of PCSK9. In both mice and non-human primates, a bivalent VLP vaccine targeting two distinct epitopes on PCSK9 elicited strong and durable antibody responses and lowered cholesterol levels. In macaques, a VLP vaccine targeting a single PCSK9 epitope was only effective at lowering LDL-C levels in combination with statins, whereas immunization with the bivalent vaccine lowered LDL-C without requiring statin co-administration. These data highlight the efficacy of an alternative, vaccine-based approach for lowering LDL-C.

Dihydromyricetin promotes LDL metabolism in HepG2 cells through the PCSK9/LDLR pathway

ABSTRACT Low-density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) play a pivotal role by regulating plasma low-density lipoprotein cholesterol (LDL-c) levels. Dihydromyricetin (DMY), the most abundant natural flavonoid in rattan tea, has proven anti-atherogenic effects, but the underlying molecular mechanisms remain poorly understood. Therefore, we studied the effects of DMY on LDLR and PCSK9. The results showed DMY promoted LDLR protein and mRNA expression and increased LDL uptake in HepG2 cells. DMY inhibited intracellular PCSK9 protein and mRNA expression. And it also significantly reduced PCSK9 levels in the cell culture medium. Furthermore, DMY inhibited the expression of PCSK9 through the liver nuclear transcription factor 1 A (HNF1A) and increased the protein expression of LDLR. Taken together, our results support the idea that DMY regulates LDL-c metabolism through PCSK9/LDLR signaling. This study reveals the potential mechanism of DMY’s anti-atherogenic effect and provides a theoretical basis for dietary DMY supplementation.

Genetic Testing Enables the Diagnosis of Familial Hypercholesterolemia Underdiagnosed by Clinical Criteria: Analysis of Japanese Early-Onset Coronary Artery Disease Patients.

Definitive diagnosis of familial hypercholesterolemia (FH) is paramount for the risk management of patients and their relatives. The present study aimed to investigate the frequency of gene variants contributing to low-density lipoprotein cholesterol (LDL-C) metabolism and their clinical relevance in patients with early-onset coronary artery disease (EOCAD). Among 63 consecutive patients with EOCAD (men <55 years or women <65 years) who underwent percutaneous coronary intervention (PCI) from 2013 to 2019 at Keio University Hospital, 52 consented to participate in this retrospective study. Targeted sequencing of LDLR, PCSK9, APOB, and LDLRAP1 was performed. Of the 52 patients enrolled (42 men; mean age: 50 ± 6 years), one (LDLR, c.1221_1222delCGinsT) harbored a pathogenic mutation, and one (APOB, c.10591A>G) harbored variants of uncertain significance. Both the patients harboring the variants were male, showing no history of diabetes mellitus or chronic kidney disease, no family history of EOCAD, and no physical findings of FH (i.e., tendon xanthomas or Achilles tendon thickening). Patients harboring the LDLR variant had three-vessel disease, were on a statin prescription at baseline, and had stable LDL-C levels; however, the case showed a poor response to the intensification of medication after PCI. Approximately 3.8% of patients with EOCAD harbored variants of gene related to LDL-C metabolism; there were no notable indicators in the patients' background or clinical course to diagnose FH. Given the difficulty in diagnosing FH based on clinical manifestations and family history, genetic testing could enable the identification of hidden risk factors and provide early warnings to their relatives.

Cranberry juice decreases oxidative stress and improves glucose metabolism in patients with rheumatoid arthritis supplemented with fish oil

BackgroundBeneficial effects of fish oil n-3 polyunsaturated fatty acids (PUFAs) have been reported in rheumatoid arthritis (RA), however, high doses of n-3 fatty acids have been associated with increased total and LDL cholesterol and impaired glucose metabolism. Cranberry products have been reported to improve markers of oxidative stress, inflammation, and the metabolic profile in patients with type 2 diabetes mellitus and with metabolic syndrome. We hypothesized that including low-energy cranberry juice on a regimen of fish oil supplementation could improve oxidative stress and attenuate the undesirable effects of fish oil in lipid and glucose metabolism in patients with RA. MethodsA 90-days randomized controlled trial was conducted. Patients (n = 70) were assigned to one of three groups: control (C); fish oil (FO) received 3 g of fish oil PUFAs supplementation/day; and fish oil and cranberry (FOCR) received 3 g of fish oil PUFAs and 500 mL of cranberry juice/day. ResultsThere was no difference in parameters between FO and the C. FOCR group showed decreased glucose (p = 0.0225), lipid (p = 0.0079), protein (p = 0.0063) oxidation, and Oxidative Stress Index (p = 0.0375) values compared to FO. FOCR reduced glucose values (p = 0.0104), triacylglycerol (p = 0.0065), protein oxidation (p = 0.0042) and Oxidative Stress Index (OSI) (p = 0.0053) compared to the C. Compared to baseline, FO group decreased triacylglycerol (p = 0.0374) and increased glucose (p 0.0001), whereas FOCR group decreased triacylglycerol (p = 0.0398) values. Conclusion500 mL/day of reduced-calorie cranberry juice in patients with RA using fish oil supplementation decreased lipid, protein oxidation and OSI.

Mechanism of the Regulation of Plasma Cholesterol Levels by PI(4,5)P2.

Elevated low-density lipoprotein (LDL) cholesterol (LDLc) is one of the most well-established risk factors for cardiovascular disease, while high levels of high-density lipoprotein (HDL) cholesterol (HDLc) have been associated with protection from cardiovascular disease. Cardiovascular disease remains one of the leading causes of death worldwide; thus it is important to understand mechanisms that impact LDLc and HDLc metabolism. In this chapter, we will discuss molecular processes by which phosphatidylinositol-(4,5)-bisphosphate, PI(4,5)P2, is thought to modulate LDLc or HDLc. Section 1 will provide an overview of cholesterol in the circulation, discussing processes that modulate the various forms of lipoproteins (LDL and HDL) carrying cholesterol. Section 2 will describe how a PI(4,5)P2 phosphatase, transmembrane protein 55B (TMEM55B), impacts circulating LDLc levels through its ability to regulate lysosomal decay of the low-density lipoprotein receptor (LDLR), the primary receptor for hepatic LDL uptake. Section 3 will discuss how PI(4,5)P2 interacts with apolipoprotein A-I (apoA1), the key apolipoprotein on HDL. In addition to direct mechanisms of PI(4,5)P2 action on circulating cholesterol, Sect. 4 will review how PI(4,5)P2 may indirectly impact LDLc and HDLc by affecting insulin action. Last, as cholesterol is controlled through intricate negative feedback loops, Sect. 5 will describe how PI(4,5)P2 is regulated by cholesterol.

Physiological level of LDL cholesterol and lipoprotein metabolism with apoprotein B100. An update for the clinician

Teleologically (physiological end or purpose), LP-apoB100 are macromolecules whose biological objective is to package in the liver within very-low-density lipoproteins (VLDL) (density 0.96-1.006 g/L), essential hydrophobic lipids, especially triglycerides (TG) and esterified cholesterol. Once assembled, the hepatocyte secretes VLDL into the systemic circulation; this way, essential hydrophobic lipids (insoluble in water) can be transported from the liver to peripheral tissues in an aqueous medium such as plasma. In the systemic circulation and influenced by the energy balance, VLDL (by hydrolysis of its triglycerides), fulfill its primary physiological purpose, releasing glycerol and especially fatty acids (FA) towards the cardiac and skeletal muscle tissues. Which, in turn, will be used as an energy substrate for beta-oxidation and adenosine triphosphate (ATP) generation or towards the adipose tissue to be used as a substrate for the resynthesis of triglycerides (adipocyte lipogenesis) and its eventual rehydrolysis with the release of fatty acids (adipocyte lipolysis).

Targets of statins intervention in LDL-C metabolism: Gut microbiota.

Increasing researches have considered gut microbiota as a new “metabolic organ,” which mediates the occurrence and development of metabolic diseases. In addition, the liver is an important organ of lipid metabolism, and abnormal lipid metabolism can cause the elevation of blood lipids. Among them, elevated low-density lipoprotein cholesterol (LDL-C) is related with ectopic lipid deposition and metabolic diseases, and statins are widely used to lower LDL-C. In recent years, the gut microbiota has been shown to mediate statins efficacy, both in animals and humans. The effect of statins on microbiota abundance has been deeply explored, and the pathways through which statins reduce the LDL-C levels by affecting the abundance of microbiota have gradually been explored. In this review, we discussed the interaction between gut microbiota and cholesterol metabolism, especially the cholesterol-lowering effect of statins mediated by gut microbiota, via AMPK-PPARγ-SREBP1C/2, FXR and PXR-related, and LPS-TLR4-Myd88 pathways, which may help to explain the individual differences in statins efficacy.

Recent Advances on the Roles of PCSK-9 Inhibitors in the Management of Acute Ischemic Stroke Patients.

Acute ischemic stroke (AIS) represents an important cause of disability and death. Since only a minor percentage of patients with AIS are eligible for acute therapy, the management of risk factors is mandatory. An important risk factor of AIS is hyperlipemia. The current guidelines recommend a strict correction of it. Statins are recommended as the first-line treatment, while proprotein convertase subtilin/kexin type 9 (PCSK-9) inhibitors are administered as a second or even third option when the goal for a low-density lipoprotein cholesterol (LDL-C) level is not achieved. PCSK-9 inhibitors effectively decrease the LDL-C levels through the inhibition of PCSK-9-LDL-receptor complex formation. The in-depth understanding of the PCSK-9 protein mechanism in the metabolism of LDL-C led to the development of effective targeted approaches. Furthermore, a better understanding of the LDL-C metabolic pathway led to the development of newer approaches, which increased the therapeutic options. This article aims to offer an overview of the PCSK-9 inhibitors and their mechanism in reducing the LDL-C levels. Moreover, we will present the main indications of the current guidelines for patients with hyperlipemia and for those who have suffered an acute ischemic stroke, as well as the importance of LDL-C reduction in decreasing the rate of a recurrence.

Early life exposure to the Chinese Famine of 1959-1961 is an independent risk factor of adulthood elevated homocysteine, hyperuricemia, high LDL, and hypertension.

Famine exposure in early life was associated with cardiovascular diseases in later life. Whether biochemical surrogates of cardiovascular diseases, such as homocysteine and uric acid, are also associated with famine exposure is unknown so far. Data were derived from a population-based cross-sectional study in the Hunan Province of China, which was heavily affected by the Famine in 1959-1961. A total of 1,150 adults born between 1952and1964 were selected, and 5 cohorts were defined: no exposure, fetal, early childhood, mid-childhood, and late childhood exposure. Compared with the no-famine exposure group, participants exposed to famine in their fetal period had a higher risk of high homocysteine in adulthood with OR of 2.21 (95% CI: 1.01-4.83), whereas famine exposures in early, mid, or late childhood were not significantly associated with high homocysteine in adulthood. Similarly, participants in the fetal famine exposure group had a 1.59-fold higher risk of hyperuricemia (OR = 2.59, 95% CI: 1.07-5.30) and a 2.03-fold higher risk of high low-density lipoprotein cholesterol (LDL) (OR = 0.03, 95% CI: 1.35-6.78) in adulthood compared to those without famine exposure, respectively. We furthermore conducted a meta-analysis including 16 studies regarding the association between fetal famine exposure and adulthood hypertension, including our study. The meta-analysis, including 34,804, subjects showed that fetal famine exposure is associated with a higher risk of adulthood hypertension (OR=1.22, 95% CI: 1.07-1.40). Taken together, fetal famine exposure is related to higher odds of cardio-metabolic risk factors, such as high homocysteine, hyperuricemia, and LDL as well as hypertension, suggesting that undernutrition during fetal life may affect metabolism of homocysteine, uric acid, and LDL in adulthood.

Leu22_Leu23 Duplication at the Signal Peptide of PCSK9 Promotes Intracellular Degradation of LDLr and Autosomal Dominant Hypercholesterolemia.

PCSK9 (Proprotein convertase subtilisin/kexin type 9) regulates LDL-C (low-density lipoprotein cholesterol) metabolism by targeting LDLr (LDL receptor) for lysosomal degradation. PCSK9 gain-of-function variants cause autosomal dominant hypercholesterolemia by reducing LDLr levels, the D374Y variant being the most severe, while loss-of-function variants are associated with low LDL-C levels. Gain-of-function and loss-of-function activities have also been attributed to variants occurring in the PCSK9 signal peptide. Among them, L11 is a very rare PCSK9 variant that seems to increase LDL-C values in a moderate way causing mild hypercholesterolemia. Using molecular biology and biophysics methodologies, activities of L8 and L11 variants, both located in the leucine repetition stretch of the signal peptide, have been extensively characterized in vitro. L8 variant is not associated with increased LDLr activity, whereas L11 activity is increased by ≈20% compared with wt PCSK9. The results suggest that the L11 variant reduces LDLr levels intracellularly by a process resulting from impaired cleavage of the signal peptide. This would lead to less efficient LDLr transport to the cell membrane and promote LDLr intracellular degradation. Deletion of a leucine in the signal peptide in L8 variant does not affect PCSK9 activity, whereas the leucine duplication in the L11 variant enhances LDLr intracellular degradation. These findings highlight the importance of deep in vitro characterization of PCSK9 genetic variants to determine pathogenicity and improve clinical diagnosis and therapy of inherited familial hypercholesterolemia disease.

Reduction of High Cholesterol Levels by a Preferably Fixed-Combination Strategy as the First Step in the Treatment of Hypertensive Patients with Hypercholesterolemia and High/Very High Cardiovascular Risk: A Consensus Document by the Italian Society of Hypertension.

The primary and secondary prevention strategies of atherosclerotic cardiovascular disease (ASCVD) largely rely on the management of arterial hypertension and hypercholesterolemia, two major risk factors possibly linked in pathophysiological terms by the renin-angiotensin system activation and that often coexist in the same patient synergistically increasing cardiovascular risk. The classic pharmacologic armamentarium to reduce hypercholesterolemia has been based in the last two decades on statins, ezetimibe, and bile acid sequestrants. More recently numerous novel, additive resources targeting different pathways in LDL cholesterol metabolism have emerged. They include drugs targeting the proprotein convertase subtilisin/kexin type 9 (PCSK9) (inhibitory antibodies; small-interfering RNAs), the angiopoietin-like protein 3 (inhibitory antibodies), and the ATP-citrate lyase (the inhibitory oral prodrug, bempedoic acid), with PCSK9 inhibitors and bempedoic acid already approved for clinical use. With the potential of at least halving LDL cholesterol levels faster and more effectively with the addition of ezetimibe than with high-intensity statin alone, and even more with the addition of the novel available drugs, this document endorsed by the Italian Society of Hypertension proposes a novel paradigm for the treatment of the hypertensive patient with hypercholesterolemia at high and very high ASCVD risk. Our proposal is based on the use as a first-line of a preferably fixed combination of lipid-lowering drugs, under the motto “Our goal: achieve control. No setback: combine and check”.

Vaccine targeting ANGPTL3 ameliorates dyslipidemia and associated diseases in mouse models of obese dyslipidemia and familial hypercholesterolemia

SummaryDyslipidemia is a risk factor for cardiovascular disease (CVD), a major cause of death worldwide. Angiopoietin-like protein 3 (ANGPTL3), recognized as a new therapeutic target for dyslipidemia, regulates the metabolism of low-density lipoprotein-cholesterol (LDL-C) and triglycerides. Here, we design 3 epitopes (E1-E3) for use in development of a peptide vaccine targeting ANGPTL3 and estimate effects of each on obesity-associated dyslipidemia in B6.Cg-Lepob/J (ob/ob) mice. Vaccination with the E3 (32EPKSRFAMLD41) peptide significantly reduces circulating levels of triglycerides, LDL-C, and small dense (sd)-LDL-C in ob/ob mice and decreases obese-induced fatty liver. Moreover, E3 vaccination does not induce cytotoxicity in ob/ob mice. Interestingly, the effect of E3 vaccination on dyslipidemia attenuates development of atherosclerosis in B6.KOR/StmSlc-Apoeshl mice fed a high-cholesterol diet, which represent a model of severe familial hypercholesterolemia (FH) caused by ApoE loss of function. Taken together, ANGPTL3 vaccination could be an effective therapeutic strategy against dyslipidemia and associated diseases.

Treatment with PCSK9 Inhibitors in Patients with Familial Hypercholesterolemia Lowers Plasma Levels of Platelet-Activating Factor and Its Precursors: A Combined Metabolomic and Lipidomic Approach.

Introduction: Familial hypercholesterolemia (FH) is characterized by extremely high levels of circulating low-density lipoprotein cholesterol (LDL-C) and is caused by mutations of genes involved in LDL-C metabolism, including LDL receptor (LDLR), apolipoprotein B (APOB), or proprotein convertase subtilisin/Kexin type 9 (PCSK9). Accordingly, PCSK9 inhibitors (PCSK9i) are effective in LDL-C reduction. However, no data are available on the pleiotropic effect of PCSK9i. To this end, we performed an untargeted metabolomics approach to gather a global view on changes in metabolic pathways in patients receiving treatment with PCSK9i. Methods: Twenty-five FH patients starting treatment with PCSK-9i were evaluated by an untargeted metabolomics approach at baseline (before PCSK9i treatment) and after 12 weeks of treatment. Results: All the 25 FH subjects enrolled were on maximal tolerated lipid-lowering therapy prior to study entry. After a 12 week treatment with PCSK9i, we observed an expected significant reduction in LDL-cholesterol levels (from 201.0 ± 69.5 mg/dL to 103.0 ± 58.0 mg/dL, p < 0.001). The LDL-C target was achieved in 36% of patients. After peak validation and correction, after 12 weeks of PCSK9i treatment as compared to baseline, we observed increments in creatine (p-value = 0.041), indole (p-value = 0.045), and indoleacrylic acid (p-value= 0.045) concentrations. Conversely, significant decreases in choline (p-value = 0.045) and phosphatidylcholine (p-value < 0.01) together with a reduction in platelet activating factor (p-value = 0.041) were observed. Conclusions: Taking advantage of untargeted metabolomics, we first provided evidence of concomitant reductions in inflammation and platelet activation metabolites in FH patients receiving a 12 week treatment with PCSK9i.

Cohort Generation and Characterization of Patient-Specific Familial Hypercholesterolemia Induced Pluripotent Stem Cells.

Homozygous familial hypercholesterolemia (hoFH) is a rare disorder caused primarily by pathological mutations in the low-density lipoprotein receptor (LDLR), which disrupts LDL-cholesterol (LDL-C) metabolism homeostasis. hoFH patients are at extremely high risk for cardiovascular disease and are resistant to standard therapies. LDLR knockout animals and in vitro cell models overexpressing different mutations have proved useful, but may not fully recapitulate human LDLR mutation biology. We and others have generated induced pluripotent stem cells (iPSC) from hoFH patient's fibroblasts and T cells and demonstrated their ability to recapitulate hoFH biology. In this study, we present the generation and characterization of a cohort of seven hoFH-iPSC lines derived from peripheral blood mononuclear cells (PBMC) collected from four homozygous and three compound heterozygous patients. The hoFH-iPSC cohort demonstrated a wide range of LDLR expression and LDL-C internalization in response to rosuvastatin that correlated with the predicted pathogenicity of the mutation. We were able to confirm that hoFH-iPSC cohort were pluripotent by differentiation toward all three germ layers and specifically to hepatocyte-like cells (HLC), the cell with primary LDL-C metabolic regulatory control, by expression of hepatocyte markers. hoFH patient PBMC-derived iPSC recapitulate the LDLR dysfunction of their specific mutation. They were capable of differentiating to HLC and could be useful for early developmental studies, pharmacology/toxicology, and potentially autologous cell therapy.

The link between proprotein convertase subtilisin/kexin 9 serum levels and E670G gene polymorphism and the risk of ischemic stroke in patients of the south of Egypt

BackgroundProprotein convertase subtilisin/kexin 9 (PCSK9) has a role in low-density lipoprotein-cholesterol metabolism, which relates to the initiation and progression of atherosclerosis and hence cerebrovascular ischemic stroke (CIS). This hospital-based study aims to investigate whether PCSK9 serum levels and E670G single nucleotide polymorphism (SNP) of the PCSK9 gene associated with a higher incidence of atherosclerosis and CIS among a patient series in the south of Egypt or not.Materials and methodsA total of 100 patients with ischemic stroke (68 with atherosclerotic ischemic stroke and 32 nonatherosclerotic ischemic stroke), together with 100 age-matched and sex-matched healthy controls, were enrolled in this study. Genotyping of E670G SNP was performed by restriction fragment length polymorphism PCR. The serum PCSK9 levels were determined using ELISA kit, whereas serum lipid profiles were determined using colorimetric methods.ResultsHigher serum PCSK9 levels were significantly noticed in atherosclerotic ischemic stroke. Genotyping distribution of E670G gene polymorphism of PCSK9 gene showed higher distribution in both patients with ischemic stroke and those with atherosclerotic ischemic stroke. The GA heterozygous carriers were at risk of developing ischemic stroke (odds ratio = 2.234, confidence interval = 1.2323–4.0509, P = 0.0081) when compared with controls. Carriers of G allele of E670G SNP had significantly higher serum total cholesterol and low-density lipoprotein-cholesterol levels in atherosclerotic ischemic stroke subgroup.ConclusionSerum PCSK9 levels were significantly higher among patients with atherosclerotic CIS. The gain-of-function mutation in carriers of the G allele of E670G SNP plays an essential role in the pathogenesis of lipid related diseases, and it affects atherogenesis. These findings make the G allele of E670G SNP of PCSK9 gene a possible genetic risk factor for ischemic stroke among atherosclerotic patients.

Combined hyperlipidemia is genetically similar to isolated hypertriglyceridemia

Combined hyperlipidemia (CHL) is a common disorder defined by concurrently elevated low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) levels. Despite decades of study, the genetic basis of CHL remains unclear. To characterize the genetic profiles of patients with CHL and compare them to those in patients with isolated hypercholesterolemia and isolated hypertriglyceridemia (HTG). DNA from 259, 379 and 124 patients with CHL, isolated hypercholesterolemia and isolated HTG, respectively, underwent targeted sequencing. We assessed: 1) rare variants disrupting canonical LDL-C or TG metabolism genes; and 2) two polygenic scores-for elevated LDL-C and TG-calculated using common trait-associated single-nucleotide polymorphisms (SNPs). Genetic profiles were compared against 1000 Genomes Project controls. Both CHL and isolated HTG patients had significantly increased odds of a high polygenic score for TG: 2.50 (95% confidence interval [CI] 1.61-3.88; P<0.001) and 3.72 (95% CI 2.24-6.19; P<0.001), respectively. CHL patients had neither a significant accumulation of rare variants for LDL-C or TG, nor a high polygenic score for LDL-C. In contrast, patients with isolated hypercholesterolemia had a 3.03-fold increased odds (95% CI 2.22-4.13; P<0.001) of carrying rare variants associated with familial hypercholesterolemia, while patients with isolated HTG had a 2.78-fold increased odds (95% CI 1.27-6.10; P=0.0136) of carrying rare variants associated with severe HTG. CHL is genetically similar to isolated HTG, a known polygenic trait. Both cohorts had a significant accumulation of common TG-raising variants. Elevated LDL-C levels in CHL are not associated with common or rare LDL-C-related genetic variants.