Regulation Of Lipoprotein Metabolism Research Articles

APOA1/C3/A4/A5 Gene Cluster at 11q23.3 and Lipid Metabolism Disorders: From Epigenetic Mechanisms to Clinical Practices.

The APOA1/C3/A4/A5 cluster is an essential component in regulating lipoprotein metabolism and maintaining plasma lipid homeostasis. A genome-wide association analysis and Mendelian randomization have revealed potential associations between genetic variants within this cluster and lipid metabolism disorders, including hyperlipidemia and cardiovascular events. An enhanced understanding of the complexity of gene regulation has led to growing recognition regarding the role of epigenetic variation in modulating APOA1/C3/A4/A5 gene expression. Intensive research into the epigenetic regulatory patterns of the APOA1/C3/A4/A5 cluster will help increase our understanding of the pathogenesis of lipid metabolism disorders and facilitate the development of new therapeutic approaches. This review discusses the biology of how the APOA1/C3/A4/A5 cluster affects circulating lipoproteins and the current progress in the epigenetic regulation of the APOA1/C3/A4/A5 cluster.

Abstract 17120: ARO-ANG3, an Investigational RNAi Therapeutic, Silences the Expression of ANGPTL3 and Decreases Atherogenic Lipoproteins in Patients With Mixed Dyslipidemia: ARCHES-2 Study Results

Background: Angiopoietin-like protein 3 (ANGPTL3) regulates lipoprotein metabolism by inhibiting lipoprotein and endothelial lipases. ANGPTL3 loss-of-function carriers have decreased circulating triglycerides (TGs), LDL-C, and HDL-C, and a lower risk of atherosclerotic cardiovascular disease (ASCVD). ARO-ANG3 is an investigational RNAi therapeutic designed to inhibit hepatic ANGPTL3 expression and reduce atherogenic lipoproteins. Aim: We report end-of-study results (data cutoff 09 December 2022) from ARCHES-2, a Phase 2b double-blind, placebo (pbo)-controlled study (NCT04832971) to evaluate the safety and efficacy of ARO-ANG3 in adults with mixed dyslipidemia (MD). Methods: Patients with fasting TGs 150-499 mg/dL and LDL-C ≥70 mg/dL or non-HDL-C ≥100 mg/dL were randomized to receive 50 mg, 100 mg or 200 mg ARO-ANG3 or pbo by subcutaneous injections on Day 1 and Week 12. Patients were on a stable diet and optimal lipid-lowering therapies. The primary endpoint was the percent change in TGs from baseline at Week 24. Liver fat was assessed at baseline and Week 24 in a subset of patients with hepatic steatosis. Mixed models repeated measures was used for statistical analyses. Results: At Week 24, ARO-ANG3 decreased ANGPTL3 (up to 77%), TGs (up to 56%), remnant cholesterol (up to 56%), and apolipoprotein B (apoB) (up to 20%). Other lipoproteins including LDL-C, non-HDL-C, lipoprotein(a) and HDL-C were also decreased. Liver fat decreased similarly in ARO-ANG3 and pbo groups. TEAEs were consistent with those expected in this patient population and with associated underlying comorbidities. Conclusions: ARCHES-2 data demonstrate ARO-ANG3 efficacy by significantly lowering ANGPTL3 and atherogenic triglyceride-rich lipoproteins (TRLs), LDL and total apoB in patients with MD. The favorable changes in serum lipids and lipoproteins and safety profile support the potential of ARO-ANG3 to treat residual ASCVD risk in patients with elevated TRLs not at LDL-C goal.

RNA interference targeting ANGPTL3 for triglyceride and cholesterol lowering: phase 1 basket trial cohorts

Elevated triglycerides and non-high-density lipoprotein cholesterol (HDL-C) are risk factors for atherosclerotic cardiovascular disease (ASCVD). ARO-ANG3 is an RNA interference therapy that targets angiopoietin-like protein 3 (ANGPTL3), a regulator of lipoprotein metabolism. This first-in-human, phase 1, randomized, placebo-controlled, open-label trial investigated single and repeat ARO-ANG3 doses in four cohorts of fifty-two healthy participants and one cohort of nine participants with hepatic steatosis, part of a basket trial. Safety (primary objective) and pharmacokinetics (in healthy participants) and pharmacodynamics (secondary objectives) of ARO-ANG3 were evaluated. ARO-ANG3 was generally well tolerated, with similar frequencies of treatment-emergent adverse events in active and placebo groups. Systemic absorption of ARO-ANG3 in healthy participants was rapid and sustained, with a mean Tmax of 6.0–10.5 h and clearance from plasma within 24–48 h after dosing with a mean t½ of 3.9–6.6 h. In healthy participants, ARO-ANG3 treatment reduced ANGPTL3 (mean −45% to −78%) 85 days after dose. Reductions in triglyceride (median −34% to −54%) and non-HDL-C (mean −18% to −29%) (exploratory endpoints) concentrations occurred with the three highest doses. These early-phase data support ANGPTL3 as a potential therapeutic target for ASCVD treatment. ClinicalTrials.gov identifier: NCT03747224

Angiopoietin-like proteins inhibitors: New horizons in the treatment of atherogenic dyslipidemia and familial hypercholesterolemia.

Angiopoietin-like proteins (ANGPTL) are involved in the regulation of numerous physiological and biochemical processes. ANGPTL3, 4 and 8, which are involved in the regulation of lipoprotein metabolism, are particularly important. ANGPTL3, 4 and 8 have been shown to regulate triglyceride availability depending on the nutritional status of the body. In addition, a deficiency of these proteins has been found to cause hypolipidemia (reduction of all lipid fractions). Increases in ANGPTL3, 4 and 8 appear to be associated with cardiovascular risk. Animal studies indicate that the use of ANGPTL3 (evinacumab) inhibitors significantly reduces plasma total cholesterol, triglycerides and low-density lipoprotein concentrations. The use of evinacumab in clinical trials also led to the normalization of plasma lipid concentrations in patients with atherogenic dyslipidemia and homozygous familial hypercholesterolemia. The results of these studies indicate that evinacumab may in the future be used in the treatment of lipid disorders, especially those with hypertriglyceridemia.

Fingolimod treatment modulates PPARγ and CD36 gene expression in women with multiple sclerosis.

Fingolimod is an oral immunomodulatory drug used in the treatment of multiple sclerosis (MS) that may change lipid metabolism. Peroxisome proliferator-activated receptors (PPAR) are transcription factors that regulate lipoprotein metabolism and immune functions and have been implicated in the pathophysiology of MS. CD36 is a scavenger receptor whose transcription is PPAR regulated. The objective of this study was to evaluate whether fingolimod treatment modifies PPAR and CD36 gene expression as part of its action mechanisms. Serum lipoprotein profiles and PPAR and CD36 gene expression levels in peripheral leukocytes were analysed in 17 female MS patients before and at 6 and 12 months after fingolimod treatment initiation. Clinical data during the follow-up period of treatment were obtained. We found that fingolimod treatment increased HDL-Cholesterol and Apolipoprotein E levels and leukocyte PPARγ and CD36 gene expression. No correlations were found between lipid levels and variations in PPARγ and CD36 gene expression. PPARγ and CD36 variations were significantly correlated during therapy and in patients free of relapse and stable disease. Our results suggest that PPARγ and CD36-mediated processes may contribute to the mechanisms of action of fingolimod in MS. Further studies are required to explore the relation of the PPARγ/CD36 pathway to the clinical efficacy of the drug and its involvement in the pathogenesis of the disease.

Causal associations between disorders of lipoprotein metabolism and ten cardiovascular diseases.

Disorders of lipoprotein metabolism have been linked with an increased risk of cardiovascular diseases (CVDs) but the causal association is unclear. In this study, we investigated the causal association between disorders of lipoprotein metabolism and CVDs using two-sample Mendelian randomization (MR). The exposure was obtained from Finn genome-wide association studies (14,010 cases, 197,259 controls), and the corresponding CVDs were extracted from the largest published genome-wide association studies. A random-effects inverse-variance weighted method was used for the main analyses with a complementary analysis using the weighted median and MR-Egger approaches. Multiple sensitivity analyses were performed to assess horizontal pleiotropy. The MR analysis indicated positive associations of disorders of lipoprotein metabolism with coronary artery disease (odds ratio [OR] 1.670, 95% confidence interval [CI] 1.373–2.031; p < 0.001), aortic aneurysm (OR 1.394, 95% CI 1.199–1.619; p < 0.001), heart failure (OR 1.20, 95% CI 1.115–1.294; p < 0.001), hypertension (OR 1.011, 95% CI 1.006–1.091; p < 0.001), old myocardial infarction (OR 1.004, 95% CI 1.002–1.007; p = 0.001), and stroke (OR 1.002, 95% CI 1.001–1.003; p = 0.002). There is a suggestive causal relationship between disorders of lipoprotein metabolism and atrial fibrillation (OR 1.047, 95% CI 1.006–1.091; p = 0.026) and acute myocardial infarction (OR 1.003, 95% CI 1.001–1.005; p = 0.012). There was limited evidence of a causal association between disorders of lipoprotein metabolism and peripheral vascular disease and venous thromboembolism. Our findings indicate a significant causal association between disorders of lipoprotein metabolism and many CVDs, including coronary artery disease, aortic aneurysm, heart failure, hypertension, old myocardial infarction, and stroke. These associations may be useful for development of treatment strategies that regulate lipoprotein metabolism in patients with CVD.

Circulating micro-RNAs implicated in lipoprotein metabolism in patients with familial hypercholesterolemia of unknown origin

Background and Aims : In many patients with clinical FH, no underlying genetic cause can be identified. MicroRNAs (miRs) are noncoding oligonucleotides involved in the posttranscriptional regulation of gene expression and several miRs have been shown to be associated with regulation of lipoprotein metabolism and plasma LDL-cholesterol levels. We hypothesized that mutation-negative FH is associated with different composition of plasma miRs.

ANGPTL3 and PCSK9 interact and show coordinated metabolic regulation in vitro

Background and Aims : ANGPTL3 and PCSK9 are known regulators of lipoprotein metabolism. Patients harboring homozygous loss of function mutations in the ANGPTL3 gene show reduced levels of circulating PCSK9, indicating a possible coordinate regulation of these two proteins. This study aimed to establish whether the two proteins can cross-regulate in different conditions of nutritional availability.

Antagonism of miR-148a attenuates the progression of atherosclerosis in APOBTGApobec-/-Ldlr+/- mice

Background and Aims : miR-148a is a hepatic and immune enriched miRNA that regulates lipoprotein metabolism and macrophage cholesterol homeostasis and inflammation. We have characterized miR-148a as a negative regulator of LDLR expression and activity. Moreover, we have demostrated that miR-148a regulates hepatic ABCA1 expression and circulating HDL-C levels. In addition to the regulation of circulating cholesterol, miR-148a is highly expressed in macrophages, which regulate cholesterol efflux and inflammation.

ILRUN Promotes Atherosclerosis Through Lipid-Dependent and Lipid-Independent Factors.

Common genetic variation in close proximity to the ILRUN gene are significantly associated with coronary artery disease as well as with plasma lipid traits. We recently demonstrated that hepatic inflammation and lipid regulator with ubiquitin-associated domain-like and NBR1-like domains (ILRUN) regulates lipoprotein metabolism in vivo in mice. However, whether ILRUN, which is expressed in vascular cells, directly impacts atherogenesis remains unclear. We sought to determine the role of ILRUN in atherosclerosis development in mice. For our study, we generated global Ilrun-deficient (IlrunKO) male and female mice on 2 hyperlipidemic backgrounds: low density lipoprotein receptor knockout (LdlrKO) and apolipoprotein E knockout (ApoeKO; double knockout [DKO]). Compared with littermate control mice (single LdlrKO or ApoeKO), deletion of Ilrun in DKO mice resulted in significantly attenuated both early and advanced atherosclerotic lesion development, as well as reduced necrotic area. DKO mice also had significantly decreased plasma cholesterol levels, primarily attributable to non-HDL (high-density lipoprotein) cholesterol. Hepatic-specific reconstitution of ILRUN in DKO mice on the ApoeKO background normalized plasma lipids, but atherosclerotic lesion area and necrotic area remained reduced in DKO mice. Further analysis showed that loss of Ilrun increased efferocytosis receptor MerTK expression in macrophages, enhanced in vitro efferocytosis, and significantly improved in situ efferocytosis in advanced lesions. Our results support ILRUN as an important novel regulator of atherogenesis that promotes lesion progression and necrosis. It influences atherosclerosis through both plasma lipid-dependent and lipid-independent mechanisms. These findings support ILRUN as the likely causal gene responsible for genetic association of variants with coronary artery disease at this locus and suggest that suppression of ILRUN activity might be expected to reduce atherosclerosis.

208-OR: Posttranslational Truncation of Apolipoproteins C1 and C2 and Plasma Lipids in Multiethnic Study of Atherosclerosis (MESA)

Apolipoproteins (apo) C1 and C2 are small interchangeable molecules that regulate lipoprotein metabolism. ApoC1 inhibits lipoprotein lipase (LPL) and stimulates reverse cholesterol transport while apoC2 activates LPL. Both exist as full-size native and minor truncated proteoforms; however, whether distribution of these apoC1 and C2 proteoforms may influence plasma lipids is largely unknown. Baseline plasma from 5,791 MESA participants was tested for truncated to native apoC1 and apoC2 ratios (apoC1’/C1; apoC2’/C2) . Total apoC1 and C2 concentrations were measured in a subset of 3,851 participants. Plasma lipids were measured for up to 6 times over 15 years. In adjusted models (Table) , higher apoC1’/C1 was associated with lower triglycerides (TG) and higher total (TC) and LDL cholesterol both at baseline and follow-up, and higher HDL at follow-up. Higher apoC2’/C2 was associated with lower TG and higher LDL at baseline, and higher baseline and follow-up TC and HDL. In contrast, the associations of total apoC1 and apoC2 concentrations with TG and HDL were largely in opposite directions of their proteoform ratios. For example, plasma TG were inversely associated with apoC1 and apoC2 truncation but positively associated with total apoC1 and apoC2 concentrations. Our data indicate a possible role of posttranslational apoC1 and apoC2 modification in regulating lipid metabolism. Disclosure J.Koska: None. J.Furtado: Research Support; Eli Lilly and Company, Pfizer Inc. S.Sinari: None. R.Mcclelland: None. D.Billheimer: None. P.Reaven: Research Support; AstraZeneca, Dexcom, Inc. Funding National Institutes of Health (R01-HL138969

Meet the First Authors.

Meet the First Authors.

PCSK9 mediates dyslipidemia induced by olanzapine treatment in schizophrenia patients.

It is controversial whether dyslipidemia induced by antipsychotics in schizophrenia patients is due to weight gain or direct effects of drug treatment. However, recent evidence showed that olanzapine can cause acute dyslipidemia independent of weight change, and the underlying mechanism remains unclear. To study the role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in olanzapine-induced dyslipidemia, we analyzed in schizophrenic patients and in experimental models involving mice and cells to understand the mechanism. Disturbances in lipid homeostasis caused by 8-week olanzapine treatment were prospectively evaluated in first-episode schizophrenic patients. Additionally, mice were administered olanzapine for 5 or 8 weeks to delineate liver actions for PCSK9 contributing to olanzapine-induced dyslipidemia. Olanzapine directly affected lipid metabolism, suggesting dyslipidemia is independent of weight gain in schizophrenia patients. Olanzapine administration significantly increased plasma PCSK9, which was positively correlated with the increment in low-density lipoprotein cholesterol (LDL-C) (r=0.77, p<0.001). Increased expression of PCSK9 in liver tissue of olanzapine-treated mice occurred prior to olanzapine-induced LDL-C abnormality. Hepatic sterol regulatory element binding protein-2 (SREBP-2) protein levels increased in mice treated with olanzapine but largely declined in olanzapine (10μM) treated HepG2 cells, which suggested high concentration of olanzapine-induced PCSK9 increase was not SREBP-2-dependent. However, expressions of sterol regulatory element binding protein-1c (SREBP-1c) significantly increased in the higher dose treated groups, which was consistent with PCSK9 increases. Activation of SREBP-1c after high-dose olanzapine treatment promotes PSCK9 expression, and consequently the degradation of low-density lipoprotein receptors results in LDL-C increase. Lipid disturbances caused by olanzapine are independent of weight gain. The study explored the relationship between SREBP-1c and PCSK9 in regulating lipoprotein metabolism after olanzapine treatment in vitro and in vivo. Further exploration of olanzapine-induced PCSK9 regulatory mechanisms may help identify control points for inhibition of olanzapine-mediated dyslipidemia.

Children with familial hypercholesterolemia display changes in LDL and HDL function: A cross-sectional study.

The functional status of lipoprotein particles contributes to atherogenesis. The tendency of plasma low-density lipoprotein (LDL) particles to aggregate and the ability of igh-density lipoprotein (HDL) particles to induce and mediate reverse cholesterol transport associate with high and low risk for cardiovascular disease in adult patients, respectively. However, it is unknown whether children with familial hypercholesterolemia (FH) display lipoprotein function alterations. We hypothesized that FH children had disrupted lipoprotein functions. We analyzed LDL aggregation susceptibility and HDL-apoA-I exchange (HAE), and activity of four proteins that regulate lipoprotein metabolism (cholesteryl ester transfer protein, lecithin-cholesterol acyltransferase, phospholipid transfer protein, and paraoxonase-1) in plasma samples derived from children with FH (n = 47) and from normocholesterolemic children (n = 56). Variation in lipoprotein functions was further explored using an nuclear magnetic resonance-based metabolomics profiling approach. LDL aggregation was higher, and HAE was lower in FH children than in normocholesterolemic children. LDL aggregation associated positively with LDL cholesterol (LDL-C) and negatively with triglycerides, and HAE/apoA-I associated negatively with LDL-C. Generally, the metabolomic profile for LDL aggregation was opposite of that of HAE/apoA-I. FH children displayed increased atherogenicity of LDL and disrupted HDL function. These newly observed functional alterations in LDL and HDL add further understanding of the risk for atherosclerotic cardiovascular disease in FH children.

Apolipoproteins in vascular biology and atherosclerotic disease.

Apolipoproteins are important structural components of plasma lipoproteins that influence vascular biology and atherosclerotic disease pathophysiology by regulating lipoprotein metabolism. Clinically important apolipoproteins related to lipid metabolism and atherogenesis include apolipoprotein B-100, apolipoprotein B-48, apolipoprotein A-I, apolipoprotein C-II, apolipoprotein C-III, apolipoprotein E and apolipoprotein(a). Apolipoprotein B-100 is the major structural component of VLDL, IDL, LDL and lipoprotein(a). Apolipoprotein B-48 is a truncated isoform of apolipoprotein B-100 that forms the backbone of chylomicrons. Apolipoprotein A-I provides the scaffolding for lipidation of HDL and has an important role in reverse cholesterol transport. Apolipoproteins C-II, apolipoprotein C-III and apolipoprotein E are involved in triglyceride-rich lipoprotein metabolism. Apolipoprotein(a) covalently binds to apolipoprotein B-100 to form lipoprotein(a). In this Review, we discuss the mechanisms by which these apolipoproteins regulate lipoprotein metabolism and thereby influence vascular biology and atherosclerotic disease. Advances in the understanding of apolipoprotein biology and their translation into therapeutic agents to reduce the risk of cardiovascular disease are also highlighted.

Regulation of lipoprotein metabolism by ANGPTL3, ANGPTL4, and ANGPTL8.

Triglyceride-rich lipoproteins deliver fatty acids to tissues for oxidation and for storage. Release of fatty acids from circulating lipoprotein triglycerides is carried out by lipoprotein lipase (LPL), thus LPL serves as a critical gatekeeper of fatty acid uptake into tissues. LPL activity is regulated by a number of extracellular proteins including three members of the angiopoietin-like family of proteins. In this review, we discuss our current understanding of how, where, and when ANGPTL3, ANGPTL4, and ANGPTL8 regulate lipoprotein lipase activity, with a particular emphasis on how these proteins interact with each other to coordinate triglyceride metabolism and fat partitioning.

ANGPTL3 and PCSK9 interaction and modulation in feeding and fasting conditions using HEPG2 cellular model.

Background and Aims: ANGPTL3 and PCSK9 are known regulators of lipoprotein metabolism. Patients affected by familial hypobetalipoproteinemia type 2, due to homozygous loss of function in the ANGPTL3 gene, show reduced levels of circulating PCSK9, indicating a possible coordinate regulation of these two proteins. Our study aimed at investigating a possible coregulation and interaction between ANGPTL3 and PCSK9.

Hypercholesterolemia risk associated Abca6 does not regulate lipoprotein metabolism in mice or hamster

Hypercholesterolemia has strong heritability and about 40–60% of hypercholesterolemia is caused by genetic risk factors. A number of monogenic genes have been identified so far for familial hypercholesterolemia (FH). However, in the general population, more than 90% of individuals with LDL cholesterol over 190 mg/dL do not carry known FH mutations. Large scale whole-exome sequencing has identified thousands of variants that are predicted to be loss-of-function (LoF) and each individual has a median of about twenty rare LoF variants and several hundreds more common LoF variants. However, majority of those variants have not been characterized and their functional consequence remains largely unknown. Rs77542162 is a common missense variant in ABCA6 and is strongly associated with hypercholesterolemia in different populations. ABCA6 is a cholesterol responsive gene and has been suggested to play a role in lipid metabolism. However, whether and how rs77542162 and ABCA6 regulate lipoprotein metabolism remain unknown. In current study, we systemically characterized the function of rs77542162 and ABCA6 in cultured cells and in vivo of rodents. We found that Abca6 is specifically expressed on the basolateral surface of hepatocytes in mouse liver. The rs77542162 variant disrupts ABCA6 protein stability and results in loss of functional protein. However, we found no evidence that Abca6 plays a role in lipoprotein metabolism in either normal mice or hypercholesterolemia mice or hamsters. Thus, our results suggest that Abca6 does not regulate lipoprotein metabolism in rodents and highlight the challenge and importance of functional characterization of disease-associated variants in animal models.

PPAR control of metabolism and cardiovascular functions.

Peroxisome proliferator-activated receptor-α (PPARα), PPARδ and PPARγ are transcription factors that regulate gene expression following ligand activation. PPARα increases cellular fatty acid uptake, esterification and trafficking, and regulates lipoprotein metabolism genes. PPARδ stimulates lipid and glucose utilization by increasing mitochondrial function and fatty acid desaturation pathways. By contrast, PPARγ promotes fatty acid uptake, triglyceride formation and storage in lipid droplets, thereby increasing insulin sensitivity and glucose metabolism. PPARs also exert antiatherogenic and anti-inflammatory effects on the vascular wall and immune cells. Clinically, PPARγ activation by glitazones and PPARα activation by fibrates reduce insulin resistance and dyslipidaemia, respectively. PPARs are also physiological master switches in the heart, steering cardiac energy metabolism in cardiomyocytes, thereby affecting pathological heart failure and diabetic cardiomyopathy. Novel PPAR agonists in clinical development are providing new opportunities in the management of metabolic and cardiovascular diseases.

New Insights Into the Regulation of Lipoprotein Metabolism by PCSK9: Lessons From Stable Isotope Tracer Studies in Human Subjects.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a convertase enzyme mostly produced by the liver. It is a key regulator of LDL metabolism because of its ability to enhance degradation of the LDL receptor. PCSK9 also regulates the metabolism of lipoprotein(a) [Lp(a)] and triglyceride-rich lipoproteins (TRLs). Its key role in modulating atherosclerotic cardiovascular disease (ASCVD) is supported by genetic studies and clinical outcome trials. Kinetic studies provide mechanistic insight into the role of PCSK9 in regulating the physiology and pathophysiology of plasma lipids and lipoproteins. Kinetic data have demonstrated that plasma PCSK9 concentration is inversely associated with the clearance of LDL in men. Gain-of-function mutations of PCSK9 markedly increase plasma LDL-cholesterol concentrations due to impaired LDL-apoB catabolism. Conversely, PCSK9 deficiency results in low LDL-cholesterol associated with enhanced LDL-apoB clearance. Inhibition of PCSK9 with monoclonal antibodies (such as evolocumab or alirocumab) lowers plasma LDL-cholesterol and apoB levels chiefly by upregulating the catabolism of LDL particles in healthy individuals. As monotherapy, PCSK9 inhibitor reduced Lp(a) concentrations by decreasing the production rate. However, as combination therapy, it reduced the plasma concentration of Lp(a) by increasing the fractional catabolism of Lp(a) particles. In statin-treated patients with high Lp(a), PCSK9 inhibition lowers plasma Lp(a) concentrations by accelerating the catabolism of Lp(a) particles. The effect of PCSK9 inhibition on TRL metabolism has been studied in healthy individuals and in patients with type 2 diabetes. These findings suggest that PCSK9 appears to play a less important role in TRL than LDL metabolism. Kinetic studies of PCSK9 inhibition therapy on lipoprotein metabolism in diverse high risk patient populations (such as familial hypercholesterolemia) and new therapeutic combination also merit further investigation.