Statins, PCSK9 inhibitors and cholesterol homeostasis: a view from within the hepatocyte

2017 ◽  
Vol 131 (9) ◽  
pp. 791-797 ◽  
Author(s):  
Allan D. Sniderman ◽  
Robert Scott Kiss ◽  
Thomas Reid ◽  
George Thanassoulis ◽  
Gerald F. Watts
Keyword(s):  
Channel Model ◽  
Ldl Receptor ◽  
Cholesterol Homeostasis ◽  
Lower Plasma ◽  
Pcsk9 Inhibitors ◽  
Tracer Studies ◽  
Conventional Model ◽  
Isotope Tracer ◽  
Ldl Particles ◽  
Receptor Number

Statins and PCSK9 inhibitors dramatically lower plasma LDL levels and dramatically increase LDL receptor number within hepatocyte cell membranes. It seems self-evident that total clearance of LDL particles from plasma and total delivery of cholesterol to the liver must increase in consequence. However, based on the results of stable isotope tracer studies, this analysis demonstrates the contrary to be the case. Statins do not change the production rate of LDL particles. Accordingly, at steady state, the clearance rate cannot change. Because LDL particles contain less cholesterol on statin therapy, the delivery of cholesterol to the liver must, therefore, be reduced. PCSK9 inhibitors reduce the production of LDL particles and this further reduces cholesterol delivery to the liver. With both agents, a larger fraction of a smaller pool is removed per unit time. These findings are inconsistent with the conventional model of cholesterol homeostasis within the liver, but are consistent with a new model of regulation, the multi-channel model, which postulates that different lipoprotein particles enter the hepatocyte by different routes and have different metabolic fates within the hepatocyte. The multi-channel model, but not the conventional model, may explain how statins and PCSK9 inhibitors can produce sustained increases in LDL receptor number.

scholarly journals PCSK9 Biology and Its Role in Atherothrombosis

2021 ◽  
Vol 22 (11) ◽  
pp. 5880
Author(s):  
Cristina Barale ◽  
Elena Melchionda ◽  
Alessandro Morotti ◽  
Isabella Russo
Keyword(s):  
Ldl Receptor ◽  
Passive Immunization ◽  
Lipoprotein Metabolism ◽  
Cholesterol Homeostasis ◽  
Proprotein Convertase ◽  
Clinical Value ◽  
Ldl Particles ◽  
First Case ◽  
Current Therapies ◽  
Pcsk9 Inhibition

It is now about 20 years since the first case of a gain-of-function mutation involving the as-yet-unknown actor in cholesterol homeostasis, proprotein convertase subtilisin/kexin type 9 (PCSK9), was described. It was soon clear that this protein would have been of huge scientific and clinical value as a therapeutic strategy for dyslipidemia and atherosclerosis-associated cardiovascular disease (CVD) management. Indeed, PCSK9 is a serine protease belonging to the proprotein convertase family, mainly produced by the liver, and essential for metabolism of LDL particles by inhibiting LDL receptor (LDLR) recirculation to the cell surface with the consequent upregulation of LDLR-dependent LDL-C levels. Beyond its effects on LDL metabolism, several studies revealed the existence of additional roles of PCSK9 in different stages of atherosclerosis, also for its ability to target other members of the LDLR family. PCSK9 from plasma and vascular cells can contribute to the development of atherosclerotic plaque and thrombosis by promoting platelet activation, leukocyte recruitment and clot formation, also through mechanisms not related to systemic lipid changes. These results further supported the value for the potential cardiovascular benefits of therapies based on PCSK9 inhibition. Actually, the passive immunization with anti-PCSK9 antibodies, evolocumab and alirocumab, is shown to be effective in dramatically reducing the LDL-C levels and attenuating CVD. While monoclonal antibodies sequester circulating PCSK9, inclisiran, a small interfering RNA, is a new drug that inhibits PCSK9 synthesis with the important advantage, compared with PCSK9 mAbs, to preserve its pharmacodynamic effects when administrated every 6 months. Here, we will focus on the major understandings related to PCSK9, from its discovery to its role in lipoprotein metabolism, involvement in atherothrombosis and a brief excursus on approved current therapies used to inhibit its action.

PCSK9 inhibition for LDL lowering and beyond – implications for patients with peripheral artery disease

VASA ◽  
2018 ◽  
Vol 47 (3) ◽  
pp. 165-176 ◽  
Author(s):  
Katrin Gebauer ◽  
Holger Reinecke
Keyword(s):  
Cardiovascular Risk ◽  
Risk Reduction ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Past Century ◽  
Pcsk9 Inhibitors ◽  
Cardiovascular Risk Reduction ◽  
Simultaneous Application ◽  
The Past ◽  
Pcsk9 Inhibition

Abstract. Low-density lipoprotein cholesterol (LDL-C) has been proven to be a causal factor of atherosclerosis and, along with other triggers like inflammation, the most frequent reason for peripheral arterial disease. Moreover, a linear correlation between LDL-C concentration and cardiovascular outcome in high-risk patients could be established during the past century. After the development of statins, numerous randomized trials have shown the superiority for LDL-C reduction and hence the decrease in cardiovascular outcomes including mortality. Over the past decades it became evident that more intense LDL-C lowering, by either the use of highly potent statin supplements or by additional cholesterol absorption inhibitor application, accounted for an even more profound cardiovascular risk reduction. Proprotein convertase subtilisin/kexin type 9 (PCSK9), a serin protease with effect on the LDL receptor cycle leading to its degradation and therefore preventing continuing LDL-C clearance from the blood, is the target of a newly developed monoclonal antibody facilitating astounding LDL-C reduction far below to what has been set as target level by recent ESC/EAS guidelines in management of dyslipidaemias. Large randomized outcome trials including subjects with PAD so far have been able to prove significant and even more intense cardiovascular risk reduction via further LDL-C debasement on top of high-intensity statin medication. Another approach for LDL-C reduction is a silencing interfering RNA muting the translation of PCSK9 intracellularly. Moreover, PCSK9 concentrations are elevated in cells involved in plaque composition, so the potency of intracellular PCSK9 inhibition and therefore prevention or reversal of plaques may provide this mechanism of action on PCSK9 with additional beneficial effects on cells involved in plaque formation. Thus, simultaneous application of statins and PCSK9 inhibitors promise to reduce cardiovascular event burden by both LDL-C reduction and pleiotropic effects of both agents.

scholarly journals Positional Enrichment by Proton Analysis (PEPA): A One-Dimensional 1 H-NMR Approach for 13 C Stable Isotope Tracer Studies in Metabolomics

2017 ◽  
Vol 56 (13) ◽  
pp. 3531-3535 ◽  
Author(s):  
Maria Vinaixa ◽  
Miguel A. Rodríguez ◽  
Suvi Aivio ◽  
Jordi Capellades ◽  
Josep Gómez ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Tracer Studies ◽  
Stable Isotope Tracer ◽  
One Dimensional ◽  
Isotope Tracer ◽  
H Nmr

Abstract 14697: Novel Assays for Quantification of Lipoprotein-Associated (PCSK9-apoB, PCSK9-Lp(a)) Proprotein Covertase Subtilisin/Kexin Type 9 (PCKS9)

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Calvin Yeang ◽  
Yun-Seok Choi ◽  
Sang-Rok Lee ◽  
Monica L Bertoia ◽  
Eric B Rimm ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Human Plasma ◽  
Polyclonal Antibodies ◽  
Human Monoclonal Antibody ◽  
Ldl Receptor ◽  
Plasma Lipoproteins ◽  
Health Study ◽  
Clinical Samples ◽  
Ldl Particles

Background: PCSK9 is a major regulator of plasma LDL-C. Monoclonal antibodies to PCSK9 lower LDL-C by 45-65% and Lp(a) by 9-38%. The canonical function of PCSK9 is binding of LDL-receptor (LDLR) via its extracellular EGF-A domain, and subsequently mediating LDLR degradation. However, PCSK9 also weakly associates with plasma lipoproteins, with 20-40% of total plasma PCSK9 found on LDL. However, most LDL particles do not contain PCSK9. Whether PCSK9 also associates with other lipoproteins such as Lp(a) are not well described. Methods: Sensitive and quantitative sandwich-based ELISA assays were developed to measure PCSK9 associated plasma lipoproteins in both mouse and human plasma. For human plasma, commercial rabbit polyclonal antibodies binding to the C-terminal region of PCSK9 (Abgent, ThermoFisher) or REGN727 human monoclonal antibody were bound to microtiter well plates. Plasma was added and monoclonal antibodies MB47 and LPA4, binding to apoB-100 and apo(a) respectively, were used to detect PCSK9-apoB-100 and PCSK9-Lp(a) complexes with a chemiluminescent ELISA. For mouse assays, REGN727 was used as the capture antibody as it detects mouse PCSK9 and monoclonal antibody LF3 was used to detect mouse apoB. Results: PCSK9-apoB and PCSK9-Lp(a) complexes could be detected in both human plasma and in various mouse models expressing apo(a) or Lp(a). The signal to noise ratio was ~20 fold in various clinical samples, including in healthy subjects and in patients with cardiovascular disease. In 536 clinical samples from the Health Professional Follow-Up Study, PCSK9-Lp(a) correlated strongly with Lp(a) (r=0.59, p<0.001, age-adjusted) but not other lipid variables. PCSK9-apoB correlated weakly with PCSK9-Lp(a) (r=0.30, p<0.001, age-adjusted) and LDL-C (r=0.22, p<0.001, age-adjusted). These associations were virtually the same in 526 women in the Nurses’ Health Study. Conclusions: Novel ELISAs were generated to quantitate lipoprotein-associated PCSK9 in transgenic mouse and human plasma, including on apoB and Lp(a). Changes in PCSK9-Lp(a) complexes may provide insights into the Lp(a)-lowering effect of PCSK9 antibodies. Whether these assays will predict CVD outcomes waits to be determined in PCSK9 antibody and epidemiological studies.

Neoagarooligosaccharides enhance the level and efficiency of LDL receptor and improve cholesterol homeostasis

2017 ◽  
Vol 38 ◽  
pp. 529-539 ◽  
Author(s):  
Ji Hye Yang ◽  
Sam Seok Cho ◽  
Kyu Min Kim ◽  
Ji Young Kim ◽  
Eun Joo Kim ◽  
...  
Keyword(s):  
Ldl Receptor ◽  
Cholesterol Homeostasis

Neonatal Respiratory Diseases in the Newborn Infant: Novel Insights from Stable Isotope Tracer Studies

Neonatology ◽  
2016 ◽  
Vol 109 (4) ◽  
pp. 325-333 ◽  
Author(s):  
Virgilio P. Carnielli ◽  
Chiara Giorgetti ◽  
Manuela Simonato ◽  
Luca Vedovelli ◽  
Paola Cogo
Keyword(s):  
Stable Isotope ◽  
Newborn Infant ◽  
Respiratory Diseases ◽  
Tracer Studies ◽  
Stable Isotope Tracer ◽  
Isotope Tracer

4945Inclisiran-mediated reductions in Lp(a) in the ORION-1 trial

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
R M Stoekenbroek ◽  
K K Ray ◽  
U Landmesser ◽  
L A Leiter ◽  
R S Wright ◽  
...  
Keyword(s):  
Ldl Receptor ◽  
Correlation Coefficients ◽  
Pcsk9 Inhibitors ◽  
Absolute Change ◽  
Phase 2 Trial ◽  
Spearman Coefficient ◽  
Ascvd Risk ◽  
Dose Dependent ◽  
Independent Assay

Abstract Background PCSK9 inhibitors and statins both lower LDL-C by increasing LDL-receptor (LDLR) function. PCSK9 inhibitors lower Lp(a) by 20–30%, whereas statins do not lower Lp(a). The mechanism by which PCSK9 inhibitors lower Lp(a) is unclear. We assessed the role of the LDLR in Lp(a) reductions produced by inclisiran, an siRNA which prevents hepatic synthesis of PCSK9. Methods ORION-1 was a phase 2 trial of inclisiran in subjects at high ASCVD risk with elevated LDL-C on optimized statin therapy. Subjects received one dose of inclisiran (200, 300, or 500 mg) or two doses at days 1 and 90 (100, 200, or 300 mg). We assessed the correlations between % change in Lp(a) and LDL-C at Day 180 for the inclisiran groups using Spearman correlation coefficients. We additionally assessed the correlation between % change in Lp(a) and absolute change in LDL-C as a proxy for LDLR expression. Lp(a) was measured using an isoform-independent assay and LDL-C with β-quantification. Results ORION-1 included 501 subjects; mean age 63; 65% male; 73% on statins. Median baseline Lp(a) was 37.0 nmol/l (IQR: 11.5–142.0 nmol/l), median LDL-C was 117.0 (IQR: 92.5–149.5 mg/dL). Inclisiran dose-dependently lowered Lp(a) by 14% to 26%. Overall, there was a significant but weak correlation between % change in Lp(a) LDL-C (Spearman coefficient 0.35, p<0.001). This correlation appeared to be stronger at higher inclisiran doses and with repeat dosing (table), as well as in statin-users versus non-users (Spearman coefficient 0.37 vs. 0.21). The correlation between % Lp(a) change and absolute LDL-C change was weaker (0.27, p<0.001). Correlation coefficients LDL-C – Lp(a) Single-dose groups Two-dose groups Inclisiran overall 200 mg (n=60) 300 mg (n=60) 500 mg (n=60) 100 mg (n=59) 200 mg (n=60) 300 mg (n=59) Lp(a) ∼ % change LDL-C 0.22 0.26 0.22 0.29 0.47 0.51 0.35 Lp(a) ∼ absolute change LDL-C 0.35 0.12 0.04 0.22 0.45 0.24 0.27 Lp(a) ∼ % change LDL-C - Statin users 0.16 0.28 0.28 0.31 0.45 0.55 0.37 Lp(a) ∼ % change LDL-C - Non statin users 0.80 -0.08 0.09 0.10 0.63 0.09 0.21 Conclusion The dose-dependent correlation between % changes in LDL-C and Lp(a) suggests that the LDLR may be partially responsible for Lp(a) reductions produced by inclisiran. The numerically stronger correlation in statin-users supports the idea that LDL-C may compete with Lp(a) for LDLR binding especially at low LDL-C levels. Acknowledgement/Funding The Medicines Company

PCSK9 and inflammation: role of shear stress, pro-inflammatory cytokines, and LOX-1

2019 ◽  
Vol 116 (5) ◽  
pp. 908-915 ◽  
Author(s):  
Zufeng Ding ◽  
Naga Venkata K Pothineni ◽  
Akshay Goel ◽  
Thomas F Lüscher ◽  
Jawahar L Mehta
Keyword(s):  
Inflammatory Cytokines ◽  
Ldl Cholesterol ◽  
Vascular Endothelial Cells ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Pcsk9 Inhibitors ◽  
Prevention Of Atherosclerosis ◽  
Pro Inflammatory Cytokines

Abstract PCSK9 degrades low-density lipoprotein cholesterol (LDL) receptors and subsequently increases serum LDL cholesterol. Clinical trials show that inhibition of PCSK9 efficiently lowers LDL cholesterol levels and reduces cardiovascular events. PCSK9 inhibitors also reduce the extent of atherosclerosis. Recent studies show that PCSK9 is secreted by vascular endothelial cells, smooth muscle cells, and macrophages. PCSK9 induces secretion of pro-inflammatory cytokines in macrophages, liver cells, and in a variety of tissues. PCSK9 regulates toll-like receptor 4 expression and NF-κB activation as well as development of apoptosis and autophagy. PCSK9 also interacts with oxidized-LDL receptor-1 (LOX-1) in a mutually facilitative fashion. These observations suggest that PCSK9 is inter-twined with inflammation with implications in atherosclerosis and its major consequence—myocardial ischaemia. This relationship provides a basis for the use of PCSK9 inhibitors in prevention of atherosclerosis and related clinical events.

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