Plasma Proprotein Convertase Subtilisin/kexin 9 Research Articles

Predictive Value of Plasma PCSK9 Levels for Degree of Atherosclerosis and Major Adverse Cardiovascular and Cerebrovascular Events in Older Adult Patients with Non-Alcoholic Fatty Liver Disease.

This study investigated the influence of plasma proprotein convertase subtilisin/kexin 9 (PCSK9) levels on the degree of atherosclerosis and major adverse cardiovascular and cerebrovascular events (MACCE) in older adults with non-alcoholic fatty liver disease. The degree of atherosclerosis severity was assessed by the standard Gensini score quartile method. According to the degree of atherosclerosis, patients were divided into mild (0-24 points; n=84), moderate (25-53 points; n=86), and severe groups (≥54 points; n=84) and then categorized as MACCE (n=30) or non-MACCE (n=224) according to 6-month follow-up data. The patients' age, sex, smoking history, medical history, and early morning fasting venous blood, for measuring biochemical indexes, were collected. Clinical data were compared between groups and the relationship between Gensini scores and PCSK9 was evaluated. Compared with the mild group, the moderate and severe groups had higher high-sensitivity C-reactive protein(hs-CRP), PCSK9, triglycerides(TG), low-density lipoprotein cholesterol (LDL-C), and lipoprotein(a)[Lp(a)] levels and lower high-density lipoprotein cholesterol(HDL-C) levels (all P<0.05). Moreover, PCSK9 positively correlated with Gensini scores (r=0.657, P<0.01). The MACCE and non-MACCE groups had significantly different ages, statin use, Gensini scores, PCSK9, and LDL-C (all P<0.05). Multi-factorial Cox risk regression analysis showed the Gensini score (HR=1.018, 95% CI: 1.006~1.029) and PCSK9 (HR=1.147, 95% CI: 1.038~1.287) were independent risk factors for MACCE. The Gensini score and PCSK9 levels can be used as predictive indicators for the degree of illness and occurrence of MACCE in older NAFLD patients.

Resveratrol protects against postmenopausal atherosclerosis progression through reducing PCSK9 expression via the regulation of the ERα-mediated signaling pathway

Elevated circulating proprotein convertase subtilisin/kexin 9 (PCSK9) levels are an important contributor to postmenopausal atherosclerosis (AS). We have previously reported that resveratrol (RSV), as a phytoestrogen, reduces hepatocyte steatosis and PCSK9 expression in L02 cells. This study aimed to investigate how RSV reduces PCSK9 expression to inhibit postmenopausal AS progression. Here, we found that treatment of Ovx/ApoE −/− mice with RSV significantly reduced dyslipidemia, plasma PCSK9 concentration and aortic plaque area. In addition, RSV significantly inhibited liver fat accumulation and improved the hepatocyte ultrastructure. Further studies showed that RSV upregulated estrogen receptor α (ERα) expression, while reduced the liver X receptor α (LXRα) expression and sterol regulatory-element-binding protein-1c (SREBP-1c) transcriptional activity. In vitro, RSV inhibited insulin-induced elevated intracellular/extracellular PCSK9 levels, enhanced receptor-mediated uptake of low-density lipoproteins in HepG2 cells. Furthermore, RSV attenuated the activity of the SRE-dependent PCSK9 promoter. However, these effects can be partially reversed by the antiestrogen ICI 182,780. Attenuation of these changes with ERα inhibition suggest that RSV may prevent the progression of postmenopausal AS by reducing PCSK9 expression in hepatocytes through ERα-mediated signaling.

Impact of conventional lipid-lowering therapy on circulating levels of PCSK9: protocol for a systematic review and meta-analysis of randomised controlled trials

IntroductionConventional lipid-lowering agents, including statins, ezetimibe, fibrates, bile acid sequestrants, nicotinic acid, bempedoic acid and Omega-3, are essential to the management of dyslipidaemia. However, these agents have been shown to...

Engineered red blood cells carrying PCSK9 inhibitors persistently lower LDL and prevent obesity.

Low plasma levels of Proprotein Convertase Subtilisin/Kexin 9 (PCSK9) are associated with decreased low-density lipoprotein (LDL) cholesterol and a reduced risk of cardiovascular disease. PCSK9 binds to the epidermal growth factor-like repeat A (EGFA) domain of LDL receptors (LDLR), very low-density lipoprotein receptors (VLDLR), apolipoprotein E receptor 2 (ApoER2), and lipoprotein receptor–related protein 1 (LRP1) and accelerates their degradation, thus acting as a key regulator of lipid metabolism. Antibody and RNAi—based PCSK9 inhibitor treatments lower cholesterol and prevent cardiovascular incidents in patients, but their high-cost hampers market penetration. We sought to develop a safe, long-term and one-time solution to treat hyperlipidemia. We created a cDNA encoding a chimeric protein in which the extracellular N- terminus of red blood cells (RBCs) specific glycophorin A was fused to the LDLR EGFA domain and introduced this gene into mouse bone marrow hematopoietic stem and progenitor cells (HSPCs). Following transplantation into irradiated mice, the animals produced RBCs with the EGFA domain (EGFA-GPA RBCs) displayed on their surface. These animals showed significantly reduced plasma PCSK9 (66.5% decrease) and reduced LDL levels (40% decrease) for as long as 12 months post-transplantation. Furthermore, the EGFA- GPA mice remained lean for life and maintained normal body weight under a high-fat diet. Hematopoietic stem cell gene therapy can generate red blood cells expressing an EGFA—glycophorin A chimeric protein as a practical and long-term strategy for treating chronic hyperlipidemia and obesity.

Association between PCSK9 Levels and Markers of Inflammation, Oxidative Stress, and Endothelial Dysfunction in a Population of Nondialysis Chronic Kidney Disease Patients.

Proprotein convertase subtilisin/kexin 9 (PCSK9) plays an important role in lipid metabolism while available literature regarding its involvement in the pathogenesis of atherosclerosis and in the expression of genes associated with apoptosis and inflammation is constantly increasing. Patients with chronic kidney disease (CKD) experience disproportionately increased cardiovascular morbidity and mortality due to dyslipidemia, accelerated atherosclerosis, inflammation, oxidative stress, and other risk factors. In the present cross-sectional study, we investigated the possible association of serum PCSK9 levels with markers of inflammation, oxidative stress, and endothelial damage in patients with CKD. Patients and Methods. Ninety-two patients with CKD stages II-ΙV (eGFR CKD-EPI 47.3 ± 25.7 ml/min/1.73 m2, mean age 66 years, 51 men) were included in the study. Plasma PCSK9 levels were correlated with comorbidities (arterial hypertension, diabetes mellitus, and history of cardiovascular disease), renal function indices (eGFR, proteinuria–UPR/24 h), lipid parameters (LDL-cholesterol, HDL-cholesterol, triglycerides, Lp(a), APO-A1, and APO-B), and soluble biomarkers of inflammation, oxidative stress, and endothelial damage (hs-CRP, fibrinogen, 8-epiPGF2a, ox-LDL, IL-6, TNF-α, sICAM-1, and sVCAM-1). Results. The mean plasma value of PCSK9 was 278.1 ng/ml. PCSK9 levels showed direct correlation with serum triglycerides (p = 0.03), Lp(a) (p = 0.01), and sICAM-1 levels (p = 0.03). There was no significant correlation between PCSK9 levels and indices of the renal function, other lipid profile parameters, inflammatory markers, or comorbidities. Multiple regression analysis showed a significant effect of Lp(a) on PCSK9 levels, and for each unit of higher Lp(a), an increase by 3.082 is expected (95% CI: 0.935-5.228, p = 0.006). At the same time, patients receiving statins are expected to have on average 63.8 ng/ml higher PCSK9 values compared to patients not receiving statins (95% CI: 14.6-113.5, p = 0.012). Conclusion. Plasma levels of PCSK9 in nondialysis CKD patients are correlated with endothelial dysfunction and lipid metabolism parameters. Statin intake increases PCSK9 levels significantly in this patient population. PCSK9 levels are not correlated with the severity of kidney disease. Major prospective studies are necessary to investigate the role of PCSK9 in the atherosclerotic cardiovascular outcome in CKD.

Efficacy and Safety of PCSK9 Inhibitors in Hypercholesterolemia Associated With Refractory Nephrotic Syndrome

IntroductionTreatment of hypercholesterolemia in refractory nephrotic syndrome remains a therapeutic challenge. There is not enough evidence supporting the efficacy of statins, and these drugs can be associated with an increased incidence of adverse effects. Herein we summarize our clinical experience with 12 patients suffering from refractory nephrotic syndrome with associated vascular disease and uncontrolled hypercholesterolemia despite treatment with statins who were treated with proprotein convertase subtilisin kexin 9 (PCSK9) inhibitors.MethodsTwelve adult patients with primary nephrotic syndrome refractory to multiple lines of immunosuppressive treatment who suffered from clinical atheromatous vascular disease were treated with PCSK9 inhibitors according to the prescription guidelines for secondary prevention of cardiovascular events. Eight patients with refractory nephrotic syndrome without vascular disease treated with atorvastatin comprised the control group.ResultsFour weeks after treatment with PCSK9 inhibitors, a statistically significant decrease in total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels was observed without significant changes in serum albumin levels or proteinuria. The mean LDL-C decrease was 36.8% ± 4.9% mmol/L at 4 weeks and remained unchanged throughout the follow-up period. In the control group, there were no significant changes in the levels of total cholesterol or LDL-C during the follow-up period. At the diagnosis of nephrotic syndrome, plasma PCSK9 levels were 334 ± 40 ng/mL and correlated significantly with serum LDL-C levels (r = 0.49, P = 0.023). Six months after starting treatment with PCSK9 inhibitors, plasma PCSK9 levels were significantly reduced to values of 190 ± 36 ng/mL (P = 0.001) with a mean relative reduction of 42.3% ± 12.6%. No local adverse effects were seen at the injection site and no significant changes were seen in the levels of transaminase, creatine phosphokinase, or aldolase.ConclusionPCSK9 inhibitors may be an effective and safe alternative for the treatment of hypercholesterolemia associated with refractory nephrotic syndrome.

PCSK9 (Proprotein Convertase Subtilisin/Kexin 9) Enhances Platelet Activation, Thrombosis, and Myocardial Infarct Expansion by Binding to Platelet CD36.

PCSK9 (proprotein convertase subtilisin/kexin 9), mainly secreted by the liver and released into the blood, elevates plasma low-density lipoprotein cholesterol by degrading low-density lipoprotein receptor. Pleiotropic effects of PCSK9 beyond lipid metabolism have been shown. However, the direct effects of PCSK9 on platelet activation and thrombosis, and the underlying mechanisms, as well, still remain unclear. We detected the direct effects of PCSK9 on agonist-induced platelet aggregation, dense granule ATP release, integrin αIIbβ3 activation, α-granule release, spreading, and clot retraction. These studies were complemented by in vivo analysis of FeCl3-injured mouse mesenteric arteriole thrombosis. We also investigated the underlying mechanisms. Using the myocardial infarction (MI) model, we explored the effects of PCSK9 on microvascular obstruction and infarct expansion post-MI. PCSK9 directly enhances agonist-induced platelet aggregation, dense granule ATP release, integrin αIIbβ3 activation, P-selectin release from α-granules, spreading, and clot retraction. In line, PCSK9 enhances in vivo thrombosis in a FeCl3-injured mesenteric arteriole thrombosis mouse model, whereas PCSK9 inhibitor evolocumab ameliorates its enhancing effects. Mechanism studies revealed that PCSK9 binds to platelet CD36 and thus activates Src kinase and MAPK (mitogen-activated protein kinase)-extracellular signal-regulated kinase 5 and c-Jun N-terminal kinase, increases the generation of reactive oxygen species, and activates the p38MAPK/cytosolic phospholipase A2/cyclooxygenase-1/thromboxane A2 signaling pathways downstream of CD36 to enhance platelet activation, as well. Using CD36 knockout mice, we showed that the enhancing effects of PCSK9 on platelet activation are CD36 dependent. It is important to note that aspirin consistently abolishes the enhancing effects of PCSK9 on platelet activation and in vivo thrombosis. Last, we showed that PCSK9 activating platelet CD36 aggravates microvascular obstruction and promotes MI expansion post-MI. PCSK9 in plasma directly enhances platelet activation and in vivo thrombosis, and MI expansion post-MI, as well, by binding to platelet CD36 and thus activating the downstream signaling pathways. PCSK9 inhibitors or aspirin abolish the enhancing effects of PCSK9, supporting the use of aspirin in patients with high plasma PCSK9 levels in addition to PCSK9 inhibitors to prevent thrombotic complications.

PCSK9 is associated with mortality in patients with septic shock: data from the ALBIOS study

Pro-protein convertase subtilisin/kexin 9 (PCSK9) is a proenzyme primarily known to regulate low-density lipoprotein receptor re-uptake on hepatocytes. Whether PCSK9 can concurrently trigger inflammation or not remains unclear. Here, we investigated the potential association between circulating levels of PCSK9 and mortality in patients with severe sepsis or septic shock. Plasma PCSK9 levels at days 1, 2 and 7 were measured in 958 patients with severe sepsis or septic shock previously enrolled in the Albumin Italian Outcome Sepsis (ALBIOS) trial. Correlations between levels of PCSK9 and pentraxin 3 (PTX3), a biomarker of disease severity, were evaluated with ranked Spearman's coefficients. Cox proportional hazards models were used to assess the association of PCSK9 levels at day 1 with 28- and 90-day mortality. Median plasma PCSK9 levels were 278 [182-452] ngmL-1 on day 1. PCSK9 correlated positively with PTX3 at the three time-points, and patients with septic shock within the first quartile of PCSK9 showed higher levels of PTX3. Similar mortality rates were observed in patients with severe sepsis across PCSK9 quartiles. Patients with septic shock with lower PCSK9 levels on day 1 (within the first quartile) showed the highest 28- and 90-day mortality rate as compared to other quartiles. In our sub-analysis of the ALBIOS trial, we found that patients with septic shock presenting with lower plasma PCSK9 levels experienced higher mortality rate. Further studies are warranted to better evaluate the pathophysiological role of PCSK9 in sepsis.

Impact of bariatric surgery-induced weight loss on circulating PCSK9 levels in obese patients

Background and aimsTo investigate the effect of obesity and bariatric-induced weight loss on circulating levels of proprotein convertase subtilisin/kexin 9 (PCSK9) in severely obese patients. Methods and resultsIn this non-randomized interventional study, we enrolled 36 severely obese patients (BMI 43.7 ± 5.6 kg/m2), of which 20 underwent bariatric surgery, and 12 nonobese healthy controls. An oral glucose tolerance test (75-g OGTT) was performed in 31 of these obese patients at baseline (T0) and in 14 patients at 6 months after bariatric surgery (T6) to assess plasma glucose, insulin and PCSK9 levels. Plasma PCSK9 levels were also measured in 18 of these obese patients at T0 during a 2-h hyperinsulinemic-euglycemic clamp (HEC).At T0, PCSK9 levels were higher in obese patients than in controls (274.6 ± 76.7 ng/mL vs. 201.4 ± 53.3 ng/mL) and dropped after bariatric surgery (T6; 205.5 ± 51.7 ng/mL) along with BMI (from 44.1 ± 5.9 kg/m2 to 33.1 ± 5.6 kg/m2). At T6, there was also a decrease in plasma glucose (T0 vs. T6: 6.0 ± 1.8 vs. 5.0 ± 0.5 mmol/L) and insulin (15.7 ± 8.3 vs. 5.4 ± 2.1 mU/L) levels. At T0, plasma PCSK9 levels decreased during OGTT in obese patients, reaching a nadir of 262.0 ± 61.4 ng/mL at 120 min with a hyperinsulinemic peak of 75.1 ± 40.0 mU/L, at 60 min. Similarly, at T0 insulin infusion during 2-h HEC acutely reduced plasma PCSK9 levels in obese patients. The aforementioned OGTT-induced changes in plasma PCSK9 levels were not observed neither in nonobese healthy controls nor in obese patients after bariatric-surgery weight loss. ConclusionsThese results suggest a pivotal role of adipose tissue and insulin resistance on PCSK9 homeostasis in severely obese patients.

4120Anti-tumor activity of a nanoliposomal anti-PCSK9 vaccine in BALB/c mice bearing 4T1 breast cancer

Abstract Background Although suppression of proprotein convertase subtilisin/kexin 9 (PCSK9) has been known to be an effective lipid-lowering approach, the efficacy and safety of PCSK9 inhibitors in non-cardiovascular diseases, particularly cancer, are yet unknown. Purpose The present study aimed to evaluate effect of PCSK9 inhibition on cancer behavior and endpoints in mice model of breast tumor, using a nanoliposomal anti-PCSK9 vaccine. Methods The nanoliposomal anti-PCSK9 vaccine was formulated via conjugation of immunogenic PCSK9 peptide to the surface of nanoliposome particles by using DSPE-PEG-Maleimide lipid. The prepared vaccine was adsorbed to Alum adjuvant (L-IFPTA+) and immunized subcutaneously four times with a bi-weekly interval in BALB/c mice.Two weeks after the last immunization, the vaccinated and unvaccinated mice were subcutaneously inoculated with 4T1 breast carcinoma cells into the right flank. After tumor mass was palpable, the mice were randomly divided into four groups and subjected to different treatment protocols: (1) PBS (untreated control), (2) vaccine group, (3) the combination group which involved vaccinated tumor-bearing mice who received single tail vein injection of Doxil®, and (4) Doxil® (positive control) group which involved unvaccinated tumor-bearing mice who received Doxil®. To evaluate therapeutic efficacy, mouse body weight, tumor size, and survival were monitored every other day for 60 days. Results The vaccine was found to efficiently generate specific antibodies against PCSK9 in BALB/c mice, and thereby reduce concentration of plasma PCSK9 and impede its function. Evaluation of tumor size demonstrated that time to reach endpoint (TTE) of the vaccine, combination, Doxil, and control groups was 47±10, 57±4, 60±4, 39±9 days, respectively. Rate of tumor growth in vaccine, combination, and Doxil groups was decreased by 21, 48, 53%, respectively, when compared with the control group (Figure). In the vaccine group life span was increased by 4.2%, while the survival in the combination and Doxil group was significantly lower than the control group. Figure 1. Anti-PCSK9 vaccine efficacy. Conclusions Our results reveal that PCSK9 inhibition not only exerts no harmful effects, but also can moderately improve breast cancer behavior in animal model.

PCSK9 inhibitor improves cardiac function and reduces infarct size in rats with ischaemia/reperfusion injury: Benefits beyond lipid-lowering effects.

During acute cardiac ischaemia/reperfusion (I/R), an increased plasma proprotein convertase subtilisin/kexin 9 (PCSK9) level instigates inflammatory and oxidative processes within ventricular myocytes, resulting in cardiac dysfunction. Therefore, PCSK9 inhibitor (PCSK9i) might exert cardioprotection against I/R injury. However, the effects of PCSK9i on the heart during I/R injury have not been investigated. The effects of PCSK9i given at different time‐points during I/R injury on left ventricular (LV) function were investigated. Male Wistar rats were subjected to cardiac I/R injury and divided into 3 treatment groups (n = 10/group): pre‐ischaemia, during ischaemia and upon onset of reperfusion. The treatment groups received PCSK9i (Pep2‐8, 10 μg/kg) intravenously. A control group (n = 10) received saline solution. During the I/R protocol, arrhythmia scores and LV function were determined. Then, the infarct size, mitochondrial function, mitochondrial dynamics and level of apoptosis were determined. PCSK9i given prior to ischaemia exerted cardioprotection through protection of cardiac mitochondrial function, decreased infarct size and improved LV function, compared with control. PCSK9i administered during ischaemia and upon the onset of reperfusion did not provide any of those benefits. PCSK9i administered before ischaemia exerts cardioprotection, as demonstrated by the attenuation of infarct size and cardiac arrhythmia during cardiac I/R injury. The attenuation is associated with improved mitochondrial function and connexin43 phosphorylation, leading to improved LV function.

PCSK9 is Increased in Cerebrospinal Fluid of Individuals With Alcohol Use Disorder.

Recent studies have shown that alcohol use affects the regulation and expression of proprotein convertase subtilisin/kexin 9 (PCSK9). While a major role of PCSK9 in hepatic function and lipid regulation has been clearly established, other pleiotropic effects remain poorly understood. Existing research suggests a positive association between PCSK9 expression in the brain and psychopathology, with increased levels of PCSK9 in the cerebrospinal fluid (CSF) of individuals with dementia and epigenetic modifications of PCSK9 associated with alcohol use disorder (AUD). In this study, we hypothesized that chronic alcohol use would increase PCSK9 expression in CSF. PCSK9 levels in CSF were measured in individuals with AUD (n=42) admitted to an inpatient rehabilitation program and controls (n=25). CSF samples in AUD were assessed at 2 time points, at day 5 and day 21 after admission. Furthermore, plasma samples were collected and measured from the individuals with AUD. PCSK9 in CSF was significantly increased in the AUD group at day 5 and day 21 compared to the controls (p<0.0001). Plasma PCSK9 levels were correlated positively with CSF PCSK9 levels in AUD (p=0.0493). Our data suggest that PCSK9 is elevated in the CSF of individuals with AUD, which may indicate a potential role of PCSK9 in AUD. Additional studies are necessary to further elucidate the functions of PCSK9 in the brain.

PCSK9 positively correlates with plasma sdLDL in community-dwelling population but not in diabetic participants after confounder adjustment.

This study aimed to investigate the relationship between plasma proprotein convertase subtilisin kexin 9 (PCSK9) and small dense low-density lipoprptein (sdLDL) in diabetic and non-diabetic participants in a community-dwelling cohort.The plasma levels of PCSK9 and sdLDL were detected in 1766 participants (median age: 61.40 years; 733 males vs 1033 females; 383 diabetic vs 1383 non-diabetic patients) from the Pingguoyuan community of Beijing, China.Results showed that Pearson correlation analysis revealed a positive correlation between PCSK9 and sdLDL (r = 0.263, P < .001). Multiple linear regression analysis showed a significant positive correlation between plasma PCSK9 and sdLDL in the whole population study. sdLDL was used as the dependent variable, and the potential cofounders were adjusted. However, any independent relationship was not observed between circulating PCSK9 and sdLDL in the diabetic subpopulation (r = 0.269, P < .05, β = 9.591, P > .05).Thus, there is a positive correlation between plasma PCSK9 and sdLDL in a community-dwelling cohort, but not in type 2 diabetic subpopulation, after confounder adjustment.

Association between proprotein convertase subtilisin/kexin 9 (PCSK9) and lipoprotein subclasses in children with type 1 diabetes mellitus: Effects of glycemic control

Background and aimsDyslipidemia in type 1 diabetes mellitus (T1DM) is characterised by altered distributions of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subclasses. Recent studies suggested that proprotein convertase subtilisin/kexin 9 (PCSK9) may contribute to the development of dyslipidemia in T1DM. In this cross-sectional study, we investigated the association between PCSK9 and lipoprotein subclasses in young T1DM patients, with respect to glycemic control. MethodsPlasma PCSK9 and lipoprotein subclasses were determined in 207 patients with T1DM (106 boys and 101 girls), aged 13.9 ± 3.0 years and treated by intensive insulin therapy. ResultsPlasma PCSK9 levels significantly increased with worsening of glycemic control (p < 0.001). T1DM patients with poor glucoregulation had the highest proportion of small, dense LDL (sdLDL) and smaller HDL particles, as well. PCSK9 was positively associated with markers of glucose homeostasis and serum lipid parameters only in patients with suboptimal/poor glucoregulation. In well-controlled T1DM, plasma PCSK9 level was inversely associated with a relative proportion of sdLDL particles (p < 0.01) and this association remained significant in multivariate analysis. In T1DM patients with suboptimal/poor glycemic control, PCSK9 was positively associated with the proportion of the smallest HDL3c particles (p < 0.001), but negatively with HDL size (p < 0.05). ConclusionsThe extent of achieved metabolic control modifies the association between PCSK9 and lipoprotein subclasses in T1DM. Further investigations are needed to reveal whether the observed effects of glycemic control on PCSK9 and sdLDL levels have causal consequences on CVD risk in young patients with T1DM.

Hemodynamic Deterioration of Surgically Implanted Bioprosthetic Aortic Valves

BackgroundDysmetabolic profile has been associated with native aortic valve stenosis. However, there are limited data on the effects of an atherogenic milieu and its potential implications on the structural and hemodynamic deterioration of aortic bioprosthetic valves. ObjectivesThis prospective longitudinal study sought to determine the predictors and impact on outcomes of hemodynamic valve deterioration (HVD) of surgically implanted aortic bioprostheses. MethodsA total of 137 patients with an aortic bioprosthesis implanted for a median time of 6.7 (interquartile range: 5.1 to 9.1) years prospectively underwent a first (baseline) assessment with complete Doppler echocardiography, quantitation of bioprosthesis leaflet calcification by multidetector computed tomography (CT), and a fasting blood sample to assess cardiometabolic risk profile. All patients underwent a second (follow-up) Doppler echocardiography examination at 3 (interquartile range: 2.9 to 3.3) years post-baseline visit. HVD was defined by an annualized change in mean transprosthetic gradient ≥3 mm Hg/year and/or worsening or transprosthetic regurgitation by ≥1/3 class. The primary endpoint was a nonhierarchical composite of death from any cause or aortic reintervention procedure (redo surgical valve replacement or transcatheter valve-in-valve implantation) for bioprosthesis failure. ResultsThirty-four patients (25.6%) had leaflet calcification on baseline CT, and 18 patients (13.1%) developed an HVD between baseline and follow-up echocardiography. Fifty-two patients (38.0%) met the primary endpoint during subsequent follow-up after the second echocardiographic examination. Leaflet calcification (hazard ratio [HR]: 2.58; 95% confidence interval [CI]: 1.35 to 4.82; p = 0.005) and HVD (HR: 5.12; 95% CI: 2.57 to 9.71; p < 0.001) were independent predictors of the primary endpoint. Leaflet calcification, insulin resistance (homeostatic model assessment index ≥2.7), lipoprotein-associated phospholipase A2 activity (Lp-PLA2 per 0.1 nmol/min/ml increase), and high level of proprotein convertase subtilisin/kexin 9 (PCSK9) (≥305 ng/ml) were associated with the development of HVD after adjusting for age, sex, and time interval since aortic valve replacement. ConclusionsHVD identified by Doppler echocardiography is independently associated with a marked increase in the risk of valve reintervention or mortality in patients with a surgical aortic bioprosthesis. A dysmetabolic profile characterized by elevated plasma Lp-PLA2, PCSK9, and homeostatic model assessment index was associated with increased risk of HVD. The presence of leaflet calcification as detected by CT was a strong predictor of HVD, providing incremental risk-predictive capacity.

Plasma PCSK9 levels and lipoprotein distribution are preserved in carriers of genetic HDL disorders

Proprotein convertase subtilisin/kexin 9 (PCSK9), a protein regulating the number of cell-surface LDL receptors (LDLR), circulates partially associated to plasma lipoproteins. How this interaction alters PCSK9 plasma levels is still unclear. In the present study, we took advantage of the availability of a large cohort of carriers of genetic HDL disorders to evaluate how HDL defects affect plasma PCSK9 levels and its distribution among lipoproteins. Plasma PCSK9 concentrations were determined by ELISA in carriers of mutations in LCAT, ABCA1, or APOAI genes, and lipoprotein distribution was analyzed by FPLC. Carriers of one or two mutations in the LCAT gene show plasma PCSK9 levels comparable to that of unaffected family controls (homozygotes, 159.4 ng/mL (124.9;243.3); heterozygotes, 180.3 ng/mL (127.6;251.5) and controls, 190.4 ng/mL (146.7;264.4); P for trend = 0.33). Measurement of PCSK9 in plasma of subjects carrying mutations in ABCA1 or APOAI genes confirmed normal values. When fractionated by FPLC, PCSK9 peaked in a region between LDL and HDL in control subjects. In carriers of all HDL defects, lipoprotein profile shows a strong reduction of HDL, but the distribution of PCSK9 was superimposable to that of controls. In conclusion, the present study demonstrates that in genetically determined low HDL states plasma PCSK9 concentrations and lipoprotein distribution are preserved, thus suggesting that HDL may not be involved in PCSK9 transport in plasma.

Abstract 545: Evolocumab Alters LDL-cholesterol Levels but Not Glycemic Profile and Liver Lipids in Chow Fed and High fat/Cholesterol/Fructose Fed Golden Syrian Hamsters

Background: Beside its effect on LDL-cholesterol levels, proprotein convertase subtilisin/kexin9 (PCSK9) could also be linked to glucose metabolism and non-alcoholic fatty liver diseases. Here we evaluated whether Evolocumab (EVO), a monoclonal antibody targeting PCSK9, may alter glycemic profile and liver lipids in hamsters. Methods: Hamsters were maintained on either a control chow (CC) or high fat/cholesterol/fructose (HFCF) diet for 5 weeks. After 2 weeks of diet, hamsters were randomized into 2 groups, control or EVO at 30mg/kg s.c. once weekly for 3 weeks, to evaluate the effects on lipoprotein/glycemic profiles, and liver lipids. Results: When compared with CC diet, HFCF diet significantly increased total cholesterol and LDL-cholesterol levels by 87% and 102%. Hamsters fed the HFCF diet also showed higher HOMA-IR index of insulin resistance, higher blood glucose area under the curve (AUC) during an oral glucose tolerance test (OGTT), and higher liver lipids (triglycerides: +197%, total cholesterol: +421%, both p&lt;0.001 vs. CC). However, plasma PCSK9 levels were markedly reduced by 47% in HFCF fed hamsters (p&lt;0.001 vs. CC). As expected, treatment with EVO significantly increased hepatic LDL-receptor protein levels by 1.74-fold and reduced plasma LDL-cholesterol by up to 28% in CC fed hamsters (p&lt;0.01 vs. CC control). The LDL-cholesterol reduction was also observed in HFCF fed hamsters treated with EVO, but to a lesser extent (up to 16%). In both CC and HFCF fed hamsters, EVO did not alter fasting glycemia and plasma insulin levels. IN CC fed hamsters, EVO transiently reduced blood glucose levels by 15% at time 15 minutes (p&lt;0.01 vs. CC control) after an oral glucose load. However, EVO did not change blood glucose levels AUC or plasma insulin levels during the OGTT, in neither CC nor HFCF fed hamsters. As well, no change in liver lipids levels was observed in CC or HFCF fed hamsters treated with EVO. Conclusion: Our data indicate that diet-induced insulin resistance and liver steatosis in hamsters are not associated with elevated plasma PCSK9 levels, and are not altered by Evolocumab. Whether these results are specific to our hamster model and can translate to humans remains to be further investigated.

Circulating PCSK9 is lowered acutely following surgery.

A decrease in serum low-density lipoprotein cholesterol (LDL-C) is well documented after acute stress. Plasma proprotein convertase subtilisin kexin 9 (PCSK9), which promotes degradation of low-density lipoprotein receptor (LDL-R) resulting in reduced plasma clearance of low-density lipoproteins (LDL) and an increase in serum LDL-C, would be predicted to decrease. Yet, a few studies have demonstrated an increase 1-8days after acute stress. Our objective was to assess the earlier status of plasma PCSK9, within the first 24hours of onset of stress. We measured serum lipids and plasma PCSK9 in 39 patients before and soon after an elective surgical procedure (abdominal aortic aneurysm (AAA) repair). We observed an early decrease in PCSK9 following surgery, as well as a decrease in total cholesterol (TC), LDL-C, high-density lipoprotein cholesterol (HDL-C), non-high-density lipoprotein cholesterol (non-HDL-C) and triglycerides (TG). Unlike other studies which showed an increase in PCSK9 after the onset of stress, our study detected a fall in PCSK9 following acute surgical stress. The observed difference is likely due to the earlier timing of PCSK9 measurement in our study. Further studies involving serial poststress measurements for several days are needed to determine whether PCSK9 behaves as an acute-phase reactant, whether it displays a biphasic response to acute stress, and whether changes in circulating PCSK9 are responsible for lipoprotein changes observed after surgical stress. (Clinical Trial Registration: ClinicalTrials.gov study ID NCT00493389).

Plasma PCSK9 levels and lipoprotein distribution are preserved in patients with severe hypoalphalipoproteinemia

Aim: Proprotein convertase subtilisin/kexin 9 (PCSK9), a protein regulating the number of cell-surface low-density lipoprotein (LDL) receptors (LDL-R), circulates partially associated to LDL, high-density lipoproteins (HDL) and lipoprotein (a). How this interaction alters PCSK9 plasma levels is still unclear. In the present study, we investigated whether a condition of familial hypoalphalipoproteinemia (FHA), due to genetic mutations in LCAT, ABCA1 or APOAI genes, could alter PCSK9 levels and distribution among different lipoproteins.

Atherogenesis and metabolic dysregulation in LDL receptor-knockout rats.

Mechanisms of atherogenesis have been studied extensively in genetically engineered mice with disturbed cholesterol metabolism such as those lacking either the LDL receptor (Ldlr) or apolipoprotein E (apoe). Few other animal models of atherosclerosis are available. WT rabbits or rats, even on high-fat or high-cholesterol diets, develop sparse atherosclerotic lesions. We examined the effects of Ldlr deletion on lipoprotein metabolism and atherosclerotic lesion formation in Sprague-Dawley rats. Deletion of Ldlr resulted in the loss of the LDLR protein and caused a significant increase in plasma total cholesterol and triglycerides. On normal chow, Ldlr-KO rats gained more weight and were more glucose intolerant than WT rats. Plasma proprotein convertase subtilisin kexin 9 (PCSK9) and leptin levels were higher and adiponectin levels were lower in KO than WT rats. On the Western diet, the KO rats displayed exaggerated obesity and age-dependent increases in glucose intolerance. No appreciable aortic lesions were observed in KO rats fed normal chow for 64 weeks or Western diet for 16 weeks; however, after 34-52 weeks of Western diet, the KO rats developed exuberant atherosclerotic lesions in the aortic arch and throughout the abdominal aorta. The Ldlr-KO rat may be a useful model for studying obesity, insulin resistance, and early-stage atherosclerosis.