Plasma Proprotein Convertase Subtilisin/kexin Type 9 Levels Research Articles

Positive correlation between plasma PCSK9 and tissue factors levels in patients with angiographically diagnosed coronary artery disease and diabetes mellitus.

BackgroundPro-protein convertase subtilisin/kexin type 9 (PCSK9) is a secreted protein that influences plasma levels of low-density lipoprotein cholesterol (LDL-C). Both oxidized LDL and tissue factor (TF) contributed to the development of prothrombotic state. The present study aims to explore the relationship between plasma level of PCSK9 and that of TF in patient with coronary artery disease (CAD).MethodsFrom July 2013 to March 2014, we enrolled 197 consecutive patients who underwent coronary angiography because of suspected CAD at Beijing Anzhen Hospital in this study. All patients had no history of using lipid-lowering medication. Of these 197 patients (131 male and 66 female, mean age 56.9 ± 11.8 years), 81 had angiographically diagnosed CAD. Clinical data were collected. Plasma PCSK9 and TF were measured using enzyme-linked immunosorbent assay (ELISA). Levels of plasma PCSK9 and TF were compared and their correlation analyzed among different patient groups.ResultsBoth plasma levels of PCSK9 (279.8 ± 60.4 µg/L vs. 216.5 ± 45.3 µg/L, P < 0.01) and TF (156.4 ± 26.6 µg/mL vs. 112.1 ± 38.3 µg/L, P < 0.01) were significantly higher in patients with CAD, as compared with those without CAD. Correlation analysis showed plasma level of PCSK9 was significantly correlated with that of TF in both patients with and without CAD. However, multivariate regression analysis after adjustment for age, gender, smoking, alcohol, hypertension and hyperlipidemia showed that only in CAD patients with type 2 diabetes mellitus, there was significant positive correlation between plasma levels of PCSK9 and TF (β = 0.353, P < 0.01).ConclusionsThe plasma level of PCSK9 is independently and positively associated with that of TF in CAD patients with diabetes mellitus, but not in those without diabetes mellitus. Further study is needed to investigate the underlying mechanism.

PCSK9 Association With Lipoprotein(a).

Lipoprotein(a) [Lp(a)] is a highly atherogenic low-density lipoprotein-like particle characterized by the presence of apoprotein(a) [apo(a)] bound to apolipoprotein B. Proprotein convertase subtilisin/kexin type 9 (PCSK9) selectively binds low-density lipoprotein; we hypothesized that it can also be associated with Lp(a) in plasma. Characterize the association of PCSK9 and Lp(a) in 39 subjects with high Lp(a) levels (range 39-320 mg/dL) and in transgenic mice expressing either human apo(a) only or human Lp(a) (via coexpression of human apo(a) and human apolipoprotein B). We show that PCSK9 is physically associated with Lp(a) in vivo using 3 different approaches: (1) analysis of Lp(a) fractions isolated by ultracentrifugation; (2) immunoprecipitation of plasma using antibodies to PCSK9 and immunodetection of apo(a); (3) ELISA quantification of Lp(a)-associated PCSK9. Plasma PCSK9 levels correlated with Lp(a) levels, but not with the number of kringle IV-2 repeats. PCSK9 did not bind to apo(a) only, and the association of PCSK9 with Lp(a) was not affected by the loss of the apo(a) region responsible for binding oxidized phospholipids. Preferential association of PCSK9 with Lp(a) versus low-density lipoprotein (1.7-fold increase) was seen in subjects with high Lp(a) and normal low-density lipoprotein. Finally, Lp(a)-associated PCSK9 levels directly correlated with plasma Lp(a) levels but not with total plasma PCSK9 levels. Our results show, for the first time, that plasma PCSK9 is found in association with Lp(a) particles in humans with high Lp(a) levels and in mice carrying human Lp(a). Lp(a)-bound PCSK9 may be pursued as a biomarker for cardiovascular risk.

Association between plasma PCSK9 levels and 10-year progression of carotid atherosclerosis beyond LDL-C: A cohort study

BackgroundTo evaluate the association of plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) levels with the progression of carotid atherosclerosis and identify additional PCSK9-lipoprotein-atherosclerosis pathway beyond low-density lipoprotein cholesterol (LDL-C). MethodsAmong 643 participants (aged from 45 to 74years) free of cardiovascular disease at baseline, carotid ultrasound examinations were performed in 2002 (baseline) and 2012 (follow-up). None of the participants were taking lipid-lowering drugs or had detectable carotid plaques at baseline. Carotid plaque formation and total plaque area (TPA) were used to reflect 10-year progression of atherosclerosis. ResultsBaseline plasma PCSK9 levels have a wide variation, ranged from 64.60–532.20ng/mL (median: 192.57ng/mL). PCSK9 levels were significantly associated with new plaque formation after adjusting for LDL-C levels and other risk factors (relative risk for per quartile increase=1.09, 95% confidence interval: 1.03–1.15). PCSK9 levels were also linearly associated with TPA after multivariate adjustment including LDL-C (P=0.008). Among participants with the lowest or second tertile of LDL-C, PCSK9 quartiles were linearly associated with TPA (P=0.021), but the association lost significance after additional adjustment for very low-density lipoprotein cholesterol (VLDL-C) tertiles (P=0.072). Further stepwise linear regression (entry, 0.05; removal, 0.05) indicated that VLDL-C tertiles could be entered into the model but PCSK9 quartiles could not. ConclusionsPlasma PCSK9 levels are associated with 10-year progression of atherosclerosis. The LDL-independent association of PCSK9 levels may through its ability to regulate VLDL-C levels. Further research is needed to systematically investigate the role of PCSK9 for the pathogenesis of atherosclerosis, beyond LDL-C metabolism.

Plasma PCSK9 level is unrelated to blood pressure and not associated independently with carotid intima-media thickness in hypertensives.

Proprotein convertase subtilisin/kexin type 9 (PCSK9), a novel target for low-density lipoprotein cholesterol (LDL-C)-lowering therapy, has been found to possess multiple off-target effects in humans. The aim of the present study was to investigate the association of blood pressure (BP) with plasma PCSK9 levels in a large Chinese cohort and the relation of PCSK9 level to carotid intima-media thickness (cIMT) in hypertensive patients. A total of 805 patients without lipid-lowering drug therapy were consecutively enrolled. First, the relationship between BP and PCSK9 was evaluated in hypertensives and normotensives. Furthermore, we examined the relation of PCSK9 to cIMT in 256 enrolled patients who had received a carotid ultrasound test. Plasma PCSK9 levels were measured by enzyme-linked immunosorbent assay, and cITM of left and right carotid arteries was assessed by B-mode ultrasound. There was no significant difference in PCSK9 levels between hypertensives and normotensives. PCSK9 level was not associated with systolic and diastolic BP and pulse pressure in hypertensives and normotensives regardless of sex. A positive correlation between PCSK9 and maximum-IMT and mean-MIT in hypertensives was found in univariate analyses, whereas such an association was absent in normotensives. In addition, the positive association of PCSK9 with cIMT disappeared in hypertensives in multivariate analyses. PCSK9 level is not associated with systolic or diastolic BP in hypertensives or normotensives, but it positively correlates with cIMT in hypertensives in univariate but not multivariate analyses, and further researches are needed.

PCSK9 Plasma Concentrations Are Independent of GFR and Do Not Predict Cardiovascular Events in Patients with Decreased GFR.

BackgroundImpaired renal function causes dyslipidemia that contributes to elevated cardiovascular risk in patients with chronic kidney disease (CKD). The proprotein convertase subtilisin/kexin type 9 (PCSK9) is a regulator of the LDL receptor and plasma cholesterol concentrations. Its relationship to kidney function and cardiovascular events in patients with reduced glomerular filtration rate (GFR) has not been explored.MethodsLipid parameters including PCSK9 were measured in two independent cohorts. CARE FOR HOMe (Cardiovascular and Renal Outcome in CKD 2–4 Patients—The Forth Homburg evaluation) enrolled 443 patients with reduced GFR (between 90 and 15 ml/min/1.73 m2) referred for nephrological care that were prospectively followed for the occurrence of a composite cardiovascular endpoint. As a replication cohort, PCSK9 was quantitated in 1450 patients with GFR between 90 and 15 ml/min/1.73 m2 enrolled in the Ludwigshafen Risk and Cardiovascular Health Study (LURIC) that were prospectively followed for cardiovascular deaths.ResultsPCSK9 concentrations did not correlate with baseline GFR (CARE FOR HOMe: r = -0.034; p = 0.479; LURIC: r = -0.017; p = 0.512). 91 patients in CARE FOR HOMe and 335 patients in LURIC reached an endpoint during a median follow-up of 3.0 [1.8–4.1] years and 10.0 [7.3–10.6] years, respectively. Kaplan-Meier analyses showed that PCSK9 concentrations did not predict cardiovascular events in either cohort [CARE FOR HOMe (p = 0.622); LURIC (p = 0.729)]. Sensitivity analyses according to statin intake yielded similar results.ConclusionIn two well characterized independent cohort studies, PCSK9 plasma levels did not correlate with kidney function. Furthermore, PCSK9 plasma concentrations were not associated with cardiovascular events in patients with reduced renal function.

Effects of Statin Therapy on Plasma Proprotein Convertase Subtilisin/kexin Type 9 and Sortilin Levels in Statin-Naive Patients with Coronary Artery Disease.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key regulator of serum low-density lipoprotein (LDL) cholesterol levels, and sortilin is linked to lipoprotein metabolism. Although statin therapy increases PCSK9 levels, effects of this therapy on plasma sortilin levels have not been evaluated. The purpose of the present study was to examine the effects of statins on plasma PCSK9 and sortilin levels, and association of statin-induced increase in PCSK9 levels with sortilin. Serum lipid levels and plasma PCSK9 and sortilin levels were measured at baseline and 8 months after statin therapy in 90 statin-naive patients with coronary artery disease (CAD). Pitavastatin 4 mg/day was used to treat 44 patients and pravastatin 20 mg/day to treat the remaining 46 patients. For both statin groups, significant increases in hetero-dimer PCSK9 levels (pitavastatin: 31%, p＜0.0001; pravastatin: 34%, p=0.03) and decreases in sortilin levels (pitavastatin: －8%, p=0.02; pravastatin: －16%, p=0.002) were observed. Although a reduction in LDL cholesterol was greater in the pitavastatin group than in the pravastatin group, no significant differences were observed in percentage changes in hetero-dimer PCSK9 and sortilin levels. A significant positive correlation was observed between percentage changes in hetero-dimer PCSK9 levels and those in sortilin levels (pitavastatin: r=0.359, p=0.02; pravastatin: r=0.276, p=0.06). Use of pitavastatin and pravastatin increased plasma PCSK9 and decreased sortilin levels. Statin-induced increases in PCSK9 were associated with changes in sortilin in statin-naive patients with CAD.

Docosahexaenoic Acid Attenuates Cardiovascular Risk Factors via a Decline in Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Plasma Levels.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a circulating protein that regulates cholesterol metabolism by promoting LDL receptor degradation in the liver and has recently been proposed as a therapeutic target in the management of hyperlipidaemia. We investigated the impact of dietary fat on the metabolism of sterols and on plasma PCSK9 concentrations to explore likely clinical usefulness. In a post hoc analysis of a double-blind randomised crossover controlled feeding trial, the Canola Oil Multicenter Intervention Trial (COMIT), volunteers (n = 54) with at least one condition related to metabolic syndrome consumed diets with one of the following treatment oils in beverages: (1) conventional canola oil (Canola); (2) canola oil rich in docosahexanoic acid (DHA) (CanolaDHA); and (3) high-oleic acid canola oil (CanolaOleic). The enrichment in oleic acid resulted in lower plasma cholesterol concentration compared with diets enriched in DHA. Contrarily, DHA-enriched oil significantly decreased plasma PCSK9 and triacylglycerols levels, but increased circulating levels of sterols. The variations in lathosterol, sitosterol, and campesterol indicate that plasma PCSK9 levels are sensitive to changes in cholesterol synthesis and/or absorption. There was a significant correlation between plasma PCSK9 levels and plasma triacylglicerol and apolipoprotein B levels, which was not affected by dietary fat. Therefore, our results suggest that the impact of dietary fats should not be discarded as complementary treatment in the management of patients with hyperlipidaemia. These findings should be considered in the analysis of ongoing studies and may represent a cautionary note in the treatment of patients with cardiovascular risk.

GRP94 Regulates Circulating Cholesterol Levels through Blockade of PCSK9-Induced LDLR Degradation.

Clearance of circulating low-density lipoprotein cholesterol (LDLc) by hepatic LDL receptors (LDLR) is central for vascular health. Secreted by hepatocytes, PCSK9 induces the degradation of LDLR, resulting in higher plasma LDLc levels. Still, it remains unknown why LDLR and PCSK9 co-exist within the secretory pathway of hepatocytes without leading to complete degradation of LDLR. Herein, we identified the ER-resident GRP94, and more precisely its client-binding C-terminal domain, as a PCSK9-LDLR inhibitory binding protein. Depletion of GRP94 did not affect calcium homeostasis, induce ER stress, nor did it alter PCSK9 processing or its secretion but greatly increased its capacity to induce LDLR degradation. Accordingly, we found that hepatocyte-specific Grp94-deficient mice have higher plasma LDLc levels correlated with ∼ 80% reduction in hepatic LDLR protein levels. Thus, we provide evidence that, in physiological conditions, binding of PCSK9 to GRP94 protects LDLR from degradation likely by preventing early binding of PCSK9 to LDLR within the ER.

Abstract 16204: Knock-down of 24-dehydrocholesterol Reductase Suppresses SREBP2: A Novel Approach to Reduce PCSK9 in vivo

Introduction: Current therapeutic approaches to suppress the actions of proprotein convertase subtilisin/kexin type 9 (PCSK9) primarily involve monoclonal antibody. An alternative approach could be to suppress the SREBP2 pathway. Inhibition of sterol regulatory element-binding protein cleacage-activating protein (SCAP) will prevent SREBP mediated transcription of sterol biogenesis genes and PCSK9.24-dehydrocholesterol reductase (DHCR24) catalyzes the last step of cholesterol synthesis, converting desmosterol to cholesterol. Desmosterol is a strong LXR agonist and an inhibitor of SCAP. Hypothesis: We tested our hypothesis that reduction of DHCR24 expression would result in an increase in desmosterol, resulting in the suppression of SCAP and reduction of PCSK9 in vivo. Methods: In these studies, we used AAVshRNA to knock-down DHCR24 in the livers of CETP transgenic mice and WT mice. Results: Animals injected with AAVshRNA-DHCR24 resulted in 85% knockdown of DHCR24, with a concomitant 75% suppression of cholesterol synthesis, as measured by deuterium incorporation into newly made cholesterol. Knock-down of DHCR24 was also associated with up-regulation of fatty acid oxidation genes and suppression of fatty acid biosynthetic and SREBP-2 cholesterol biosynthetic pathways. Interestingly, DHCR24 knockdown was associated with a 60% decrease in plasma PCSK9 levels in CETP Tg mice (n=10, P&lt;0.001) and similar results were observed in WT mice. Conclusions: To our knowledge, this is the first in vivo study to demonstrate that PCSK9 levels can be decreased via suppression of DHCR24 in vivo . These results suggest that DHCR24 might represent a novel therapeutic target for reducing LDL-cholesterol.

Plasma proprotein convertase subtilisin/kexin type 9 levels and the risk of first cardiovascular events.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secreted protein that enhances degradation of the LDL receptor. While agents that inhibit PCSK9 markedly reduce atherogenic lipoproteins and show great promise for event reduction, it is unknown whether plasma PCSK9 levels predict incident cardiovascular events. In a nested case-control evaluation conducted in a prospective cohort of >28 000 initially healthy American women, we measured plasma concentrations of PCSK9 at baseline among 358 participants who subsequently developed major cardiovascular events (cases) and among 358 age, smoking, and hormone replacement therapy matched participants who remained free of disease during 17 years of follow-up (controls). Proprotein convertase subtilisin/kexin type 9 level was not significantly related to smoking status, hypertension, obesity, or a family history of premature cardiovascular disease but was positively associated with apolipoprotein B-100 (r = 0.20, P< 0.001), and triglycerides (r = 0.13, P = 0.004). No associations were observed between PCSK9 and apo A1, HDLC, lipoprotein(a), or high-sensitivity C-reactive protein. Despite modest positive association with atherogenic lipids, baseline levels of PCSK9 did not predict the first cardiovascular events; the odds ratios (ORs) for future vascular events for the lowest (referent) to highest baseline quartiles of PCSK9 were 1.0, 0.94, 0.98, and 1.15 (P-trend = 0.53). In contrast, the corresponding ORs for baseline apo B levels were 1.0, 1.14, 1.34, and 1.94 (P-trend = 0.002). In a large-scale primary prevention cohort, plasma levels of PCSK9 measured at baseline did not predict future cardiovascular events.

The contribution of PCSK9 levels to the phenotypic severity of familial hypercholesterolemia is independent of LDL receptor genotype

Autosomal dominant familial hypercholesterolemia (FH) is caused by genetic mutations in the LDL receptor (LDLR), its ligand apolipoprotein (apo) B, or proprotein convertase subtilisin/kexin type 9 (PCSK9). Although PCSK9 levels have been shown to correlate with LDL-cholesterol (LDL-C) levels in FH, the extent to which PCSK9 levels modulate the phenotypic severity of this disease independent of LDLR genotype remains to be clarified. ObjectiveTo assess the relationship between LDLR genotype and the plasma levels of PCSK9, LDL-C, and lipoprotein (a) (Lp(a)) in a large cohort of genetically defined FH heterozygotes (HeFH). MethodsA total of 292 HeFH carrying one of the nine French-Canadian mutations in the LDLR gene were recruited. The cohort included 226 carriers of a negative-receptor (NR) mutation and 66 carriers of a defective-receptor (DR) LDLR gene mutation. Fifty-six control subjects, who were matched with the HeFH subjects based on gender and body mass index, were also recruited. ResultsPCSK9 levels were higher in the HeFH group than in the control group (317.9±107.1ng/mL vs. 203.3±59.8ng/mL; P<0.0001). The strength of the association between PCSK9 and LDL-C levels was similar among controls (r=0.37; P=0.005) and HeFH (r=0.31; P<0.0001). Furthermore, a multiple linear regression analysis revealed that the positive correlation between PCSK9 and LDL-C levels remained significant after adjusting for LDLR genotype in the HeFH group. ConclusionThese results suggested that the contribution of PCSK9 levels to the phenotypic severity in FH heterozygotes is independent of LDLR genotype.

Plasma proprotein convertase subtilisin/kexin type 9 is associated with Lp(a) in type 2 diabetic patients

AimRecent in vitro researches have shown that plasma Lp(a) can be reduced using a proprotein convertase subtilisin/kexin type 9 (PCSK9)-inhibitory monoclonal antibody. In our clinical study we tried to investigate the association between plasma Lp(a) and PCSK9 in Type 2 diabetic patients with elevated plasma Lp(a), and to check whether such an association would be related to LDL-receptor (LDL-R) levels. MethodsPlasma PCSK9 and LDL-R concentrations were measured by sandwich ELISA methods using recombinant human PCSK9 protein and LDL-R protein as standards in a cohort with type 2 diabetic patients (n=50) compared to an age- and sex-matched control group (n=50). Both clinical and biochemical parameters were determined in all patients. ResultsPlasma PCSK9 level was significantly elevated in T2DM patients compared to controls (44.61±14.44 and 33.22±11.79ng/mL, respectively, P<0.0001). However LDL-R levels did not differ between the two groups. Remarkably, plasma PCSK9 levels were positively correlated with Lp(a) levels in whole population (r=+0.227, P=0.03) as well as in T2DM group (r=+0.398, P=0.0061) but not in control group. Multiple linear regression analysis showed that plasma Lp(a) levels were independently associated to those of PCSK9. ConclusionLp(a) has been proposed as a contributing factor to the accelerated development of macrovascular complications in T2DM. Its synergic effect with PCSK9 may explain the enhanced atherogenicity in T2DM patients.

Proprotein convertase subtilisin-kexin type 9 as a biomarker for the severity of coronary artery disease

Aim. To evaluate the relation of proprotein convertase subtilisin-kexin type 9 (PCSK9) levels to coronary artery disease (CAD).Methods. A total of 1031 consecutive individuals (552 CAD and 479 controls) were prospectively enrolled. The associations of plasma PCSK9 levels with the incidence and severity of CAD were investigated. Further, mediator analysis was performed to detect the potential mechanisms of the associations.Results. No difference in PCSK9 levels between CAD patients and controls was detected (median 224.75 versus 224.64 ng/mL, P > 0.05). However, the CAD group had higher PCSK9 levels than the control group when adjusting for the confounding factors (228.03 ± 1.01 versus 219.28 ± 1.02 ng/mL, P = 0.019). PCSK9 levels were also associated with the severity of CAD assessed by the Gensini score (GS) system (P for trend < 0.05). Logistic regression analysis showed that PCSK9 levels were associated with an increased CAD risk (OR 3.296 and 5.130 for the incidence and severity, respectively). Importantly, mediator analysis indicated that the effects of PCSK9 levels on CAD were mediated by lipid (around 20%) and inflammation (around 15%).Conclusions. PCSK9 levels were positively associated with the severity of CAD; the relatively important mechanisms including lipid and inflammation pathways were partly involved in this association.

Marine n-3 polyunsaturated fatty acids lower plasma proprotein convertase subtilisin kexin type 9 levels in pre- and postmenopausal women: A randomised study

ObjectiveTo investigate whether a supplement of 2.2g of marine n-3 polyunsaturated fatty acids (PUFA) influences plasma proprotein convertase subtilisin kexin type 9 (PCSK9) levels in pre- and postmenopausal women. MethodsNinety-two healthy women were randomly assigned to consume 2.2g marine n-3 PUFA or a control oil (thistle oil) daily for 12weeks. Adipose tissue, a long-term marker of dietary intake of seafood was collected at baseline and blood samples were drawn at baseline and after 12 weeks of supplement intake. ResultsPlasma PCSK9 levels were significantly reduced by 11.4% for premenopausal women and 9.8% for postmenopausal women after the supplement of 2.2g of marine n-3 PUFA compared with control oil. The mean change of plasma PCSK9 levels between participants receiving marine n-3 PUFA and control oil was 16.1% for premenopausal women and 13.1% for postmenopausal women. There was, however, no correlation between baseline levels of plasma PCSK9 and the fatty acid content of marine n-3 PUFA in adipose tissue. ConclusionThis study showed that 2.2g marine n-3 PUFA reduce plasma PCSK9 levels in both pre- and postmenopausal women.

Relation of resistin to proprotein convertase subtilisin-kexin type 9 levels in coronary artery disease patients with different nutritional status.

To investigate the association of resistin with proprotein convertase subtilisin-kexin type 9 (PCSK9) levels, another novel regulator of atherosclerosis, in the condition of coronary artery disease (CAD). We prospectively enrolled a total of 356 consecutive stable CAD patients who were not treated with lipid-lowering drugs in the present study. The baseline clinical characteristics were collected. Plasma PCSK9 and resistin levels were determined by ELISA. The relationship between plasma PCSK9 and resistin levels was investigated. Overall, plasma resistin exhibited a positive nonparametric correlation with PCSK9 levels (r = 0.123, p = 0.02). When the patients were classified into groups based on body mass index (BMI), the resistin correlated significantly to the PCSK9 levels in patients with BMI < 25 kg/m(2) (r = 0.162, p = 0.026) but not in patients with BMI ≥ 25 kg/m(2) (r = 0.087, p = 0.205). Multivariate regression analysis corroborated the relation between the PCSK9 and an elevated resistin level in patients with BMI < 25 kg/m(2) independently of traditional parameters including age, sex, BMI, smoking, family history of CAD, systolic blood pressure, glucose, low density lipoprotein cholesterol, white blood cell, neutrophil to lymphocyte ratio, and high-sensitive C-reactive protein. Plasma resistin was positively related to PCSK9 levels in CAD patients with normal weight, suggesting that the circulating resistin might represent a link with PCSK9 level variations in CAD progression of normal body weight.

Dietary high oleic canola oil supplemented with DHA oil attenuates plasma PCSK9 levels in humans

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a novel circulating protein, which plays an important role in regulation of cholesterol metabolism by promoting hepatic LDL receptor degradation. However, the action of dietary fat composition on PCSK9 levels remains unknown. A double‐blinded RCT, consisting of five 30‐d intervention periods, was conducted to investigate varying dietary oils on circulating PCSK9 levels in healthy humans. Treatments included 60 g/d of conventional canola oil (Canola), high oleic canola oil (CanoalOleic), high oleic canola/DHA oil blend (CanolaDHA), corn/safflower oil blend (CornSaff) and flax/safflower oil blend (FlaxSaff). PCSK9 levels using ELISA were assessed at the end of each phase. Lipid profiles (n=54) showed that CanolaDHA feeding resulted in the highest (p&lt;0.05) serum total cholesterol (TC) and LDL‐C levels among all five treatments. CanolaDHA feeding also produced the lowest (p&lt;0.05) plasma PCSK9 concentrations (204.5±9.6 ng/ml) compared to Canola (231.6±9.6 ng/ml) and CanolaOleic (230.2±9.6 ng/ml) diets. In CanolaDHA diet, PCSK9 levels correlated (r=0.35, p&lt;0.01) with TC levels but not with LDL‐C levels. Results indicate that post‐diet response in PCSK9 may be altered with CanolaDHA diet. In conclusion, the elevated LDL‐C levels from a DHA oil treatment may not be deleterious as they are accompanied by a decline in PCSK9 levels. (Supported by the Canola Council of Canada and Growing Forward II program)

Circulating PCSK9 levels are positively correlated with NMR-assessed atherogenic dyslipidaemia in patients with high cardiovascular risk.

The proprotein convertase subtilisin/kexin type 9 (PCSK9) gene regulates cholesterol homoeostasis by accelerating low-density lipoprotein receptor (LDLR) degradation resulting in the decreased catabolism of low-density lipoprotein (LDL) leading to hypercholesterolaemia. PCSK9 has also been related to other metabolic risk factors such as triglycerides (TGs) and glucose levels and body mass index (BMI). Therefore, our aim was to study the relationship between the PCSK9 and the lipid and lipoprotein profile. We studied 267 diabetic and metabolic syndrome patients who were not receiving any lipid-lowering therapy. We measured circulating lipids, cholesterol in remnant lipoproteins (RLPc) and PCSK9 levels. A detailed lipoprotein profile was determined based on NMR. Plasma PCSK9 levels were significantly and positively correlated with TG (r=0.136, P=0.033), total cholesterol (r=0.219, P<0.001) and apoB (apolipoprotein B; r=0.226, P=0.006) circulating levels and with an atherogenic profile of lipoprotein subclasses. In further detail, circulating PCSK9 levels were positively correlated with large very-low density lipoprotein (VLDL) particles, (r=0.210, P=0.001) and with their remnants, the intermediate-density lipoprotein (IDL) particles (r=0.206, P=0.001); positively correlated with smaller LDL particles (for small LDL: r=0.224, P<0.001; for medium small LDL: r=0.235, P<0.001; and for very small LDL: r=0.220, P<0.001); and with high-density lipoprotein (HDL) particles (r=0.146, P<0.001), which is mainly explained by the PCSK9 correlation with the smallest HDL particles (r=0.130, P=0.037). In addition, circulating PCSK9 levels were positively correlated with the pro-atherogenic circulating RLPc levels (r=0.171, P=0.006). All of the correlations were adjusted by age, gender and BMI. PCSK9 levels are significantly and positively correlated with atherogenic lipoproteins such as large VLDL, IDL, the smallest LDL, the smallest HDL particles and RLPc levels.

Impacts of ezetimibe on PCSK9 in rats: study on the expression in different organs and the potential mechanisms.

BackgroundPrevious studies including our group have indicated the effects of ezetimibe on increased plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) concentration, while the rapid expression in different organs and the potential molecular mechanisms for this impact have not been carefully evaluated.MethodsThirty rats were randomly divided into two groups (n = 15 for each), which were orally administrated with ezetimibe (10 mg/kg/day) or normal saline. Blood samples were obtained at day 3 after orally administration, and the PCSK9 levels were determined by ELISA. We further analyzed the mRNA expression of PCSK9, low-density lipoprotein receptor (LDLR), sterol regulator element-binding protein 2 (SREBP2), and hepatocyte nuclear factor 1 alpha (HNF-1α) by real-time PCR, as well as the protein expression by western blot, in liver, intestine and kidney respectively.ResultsEzetimibe significantly increased plasma PCSK9 levels compared with control group, while there was no significant difference between the two groups with regard to lipid profile at day 3. Moreover, ezetimibe remarkably increased the expression of PCSK9, LDLR, SREBP2 and HNF-1α in liver. Enhanced expression of PCSK9, LDLR and SREBP2 protein were found in intestine and kidney, while no changes in the expression of HNF-1α were observed in intestine and kidney of rats with ezetimibe treatment.ConclusionsThe data demonstrated that ezetimibe increased PCSK9 expression through the SREBP2 and HNF-1α pathways in different organs, subsequently resulting in elevated plasma PCSK9 levels prior to the alterations of lipid profile in rats.

The role of PCSK9 in intestinal lipoprotein metabolism: synergism of statin and ezetimibe

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a major role in the regulation of lipoprotein metabolism, mostly through control of low-density lipoprotein receptor degradation. Depletion of cellular cholesterol causes a compensatory increase in plasma PCSK9 levels, which can diminish the cholesterol-lowering power of statins and may lead to the overproduction of intestinal lipoproteins, mainly thorough the up regulation of microsomal triglyceride transfer protein and the Niemann-Pick C1-like 1 protein, the target of ezetimibe. Thus, ezetimibe therapy may counter this unwanted effect of statins, providing an additional theoretical rationale for combining the effect of ezetimibe on intestinal cholesterol absorption and that of statins on cholesterol synthesis.

Influence of physiological changes in endogenous estrogen on circulating PCSK9 and LDL cholesterol

Pharmacologically increased estrogen levels have been shown to lower hepatic and plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) levels in animals and humans. We hypothesized that physiological changes in estrogen levels influence circulating PCSK9, thereby contributing to the known wide inter-individual variation in its plasma levels, as well as to the established increase in LDL cholesterol (LDL-C) with normal aging. Circulating PCSK9, estradiol, and other metabolic factors were determined in fasting samples from 206 female and 189 male healthy volunteers (age 20-85 years), The mean levels of PCSK9 were 10% higher in females than in males (P < 0.05). PCSK9 levels were 22% higher in postmenopausal than in premenopausal (P < 0.001) females. Within the group of premenopausal females, circulating PCSK9 correlated inversely to estrogen levels, and PCSK9 was higher (305 ng/ml) in the follicular phase than in the ovulatory (234 ng/ml) or the luteal (252 ng/ml) phases (P < 0.05). Changes in endogenous estrogen levels during the menstrual cycle likely contribute to the broad inter-individual variation in PCSK9 and LDL-C in normal females. PCSK9 levels increase in females after menopause but not in men during this phase in life. This likely contributes to why LDL-C in women increases in this period.