Serum PCSK6 and corin levels are not associated with cardiovascular outcomes in patients undergoing coronary angiography.

INTRODUCTION: Proprotein convertase subtilisin/kexin-6 (PCSK6) is a secretory protein that activates corin in the heart. Higher circulating levels of corin are associated with improved cardiovascular outcomes in patients with acute myocardial infarction. This study aimed to determine the role of serum PCSK6 and corin levels in predicting cardiovascular outcomes in patients with suspected coronary artery disease (CAD). MATERIALS AND METHODS: In total, 565 patients who had undergone coronary angiography were enrolled. Serum PCSK6 and corin levels were determined before the administration of contrast media. In this study, coronary revascularization, acute myocardial infarction, acute stroke, and death were defined as cardiovascular outcomes. All patients were followed up for at least one year after coronary angiography or until the occurrence of death. RESULTS: During a median follow-up of 691 days, 67 patients (15.7%) developed composite cardiovascular outcomes after coronary angiography, including 51 incidents of coronary revascularization, 7 instances of acute myocardial infarction, 2 acute strokes, and 15 deaths. After adjustment for demographic characteristics and all significant variables in the univariate analysis, serum levels of neither PCSK6 nor corin were associated with increased risk for cardiovascular outcomes. This correlation remained insignificant in patients with underlying hypertension, diabetes mellitus, CAD, heart failure, or chronic kidney disease (CKD). However, in patients without CKD, higher serum PCSK6 levels were associated with increased risk for cardiovascular outcomes (hazard ratio 1.380; 95% confidence interval 1.023-1.862). CONCLUSIONS: We found no association between cardiovascular outcomes and pre-procedural serum levels of PCSK6 or corin in patients undergoing coronary angiography. However, an increased risk was seen in non-CKD patients with higher PCSK6 levels. Further studies are needed to verify these results.

Circulating Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Predicts Future Risk of Cardiovascular Events Independently of Established Risk Factors.

BACKGROUND: The secreted protein proprotein convertase subtilisin/kexin type 9 (PCSK9) is a promising new target for lowering plasma low-density lipoprotein cholesterol and preventing cardiovascular disease (CVD). The relationship between circulating PCSK9 and incident CVD in the general population is unknown. We investigated whether serum PCSK9 concentration is associated with incident CVD in a prospective cohort study of 4232 men and women 60 years of age at the time of recruitment. METHODS AND RESULTS: Incident CVD was recorded by matching to national registries. After 15 years of follow-up, a total of 491 incident events (fatal and nonfatal myocardial infarctions, unstable angina, deaths from coronary heart disease, fatal and nonfatal ischemic strokes) were recorded. Cox proportional hazards model was used to calculate hazard ratios with 95% confidence intervals. Baseline serum PCSK9 concentration predicted incident CVD; concentration in quartile 4 compared with quartile 1 was associated with a hazard ratio of 1.69 (95% confidence interval, 1.30-2.19) after adjustment for sex. Further adjustment for low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, lipoprotein(a), triglycerides, hypertension, diabetes mellitus, smoking, overweight, obesity, physical inactivity, and statin use resulted in a decrease in the hazard ratio to 1.48 (95% confidence interval, 1.12-1.95). CONCLUSIONS: Serum PCSK9 concentration is associated with future risk of CVD even after adjustments for established CVD risk factors. Further studies are needed to confirm this observation.

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

BACKGROUND: Impaired 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. METHODS: Lipid 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. RESULTS: PCSK9 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. CONCLUSION: In 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.

Effect of Leptin Replacement on PCSK9 in ob/ob Mice and Female Lipodystrophic Patients.

Leptin treatment has beneficial effects on plasma lipids in patients with lipodystrophy, but the underlying mechanism is unknown. Proprotein convertase subtilisin/kexin type 9 (PCSK9) decreases low-density lipoprotein (LDL) clearance, promotes hypercholesterolemia, and has recently emerged as a novel therapeutic target. To determine the effect of leptin on PCSK9, we treated male and female ob/ob mice with leptin for 4 days via sc osmotic pumps (∼24 µg/d). Leptin reduced body weight and food intake in all mice, but the effects of leptin on plasma PCSK9 and lipids differed markedly between the sexes. In male mice, leptin suppressed PCSK9 but had no effect on plasma triglycerides or cholesterol. In female mice, leptin suppressed plasma triglycerides and cholesterol but had no effect on plasma PCSK9. In parallel, we treated female lipodystrophic patients (8 females, ages 5-23 y) with sc metreleptin injections (∼4.4 mg/d) for 4-6 months. In this case, leptin reduced plasma PCSK9 by 26% (298 ± 109 vs 221 ± 102 ng/mL; n = 8; P = .008), and the change in PCSK9 was correlated with a decrease in LDL cholesterol (r(2) = 0.564, P = .03). In summary, in leptin-deficient ob/ob mice, the effects of leptin on PCSK9 and plasma lipids appeared to be independent of one another and strongly modified by sex. On the other hand, in lipodystrophic females, leptin treatment reduced plasma PCSK9 in parallel with LDL cholesterol.

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

OBJECTIVE: To 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. METHODS: Ninety-two healthy women were randomly assigned to consume 2.2g marine n-3 PUFA or a control oil (thistle oil) daily for 12 weeks. 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. RESULTS: Plasma 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. CONCLUSION: This study showed that 2.2g marine n-3 PUFA reduce plasma PCSK9 levels in both pre- and postmenopausal women.

Positive correlation of plasma PCSK9 levels with HbA1c in patients with type 2 diabetes.

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been demonstrated to be involved in not only lipid metabolism but also glucose homeostasis. Glycated haemoglobin (HbA1c ) is a 'gold standard' for monitoring long-term glycaemic control. However, the correlation of plasma PCSK9 levels with HbA1c remains undetermined. METHODS: We consecutively enrolled 805 subjects undergoing coronary angiography, including 176 patients with type 2 diabetes mellitus (T2DM) and 629 non-diabetic patients. The baseline characteristics were collected, and serum PCSK9 level was assessed by ELISA. Univariable regression analysis and multiple-variable regression analysis were used to examine the associations of PCSK9 with HbA1c . Furthermore, the HbA1c was compared across the tertiles of PCSK9 levels. And also, PCSK9 levels were compared in poorly controlled (HbA1c ≥ 7.0%) and well-controlled (HbA1c < 7.0%) patients with T2DM. RESULTS: PCSK9 levels were positively correlated with low-density lipoprotein cholesterol in both T2DM and non-T2DM. Univariable regression analysis revealed a positive association between PCSK9 and HbA1c in patients with T2DM (ß = 0.255, p = 0.001) but not in patients without diabetes (ß = 0.061, p = 0.128). Multiple-variable regression analysis exhibited that PCSK9 was independently correlated with HbA1c in T2DM after adjustment for traditional atherosclerotic risk factors (ß = 0.197, p = 0.020). Moreover, HbA1c level was higher in patients with the highest tertile of PCSK9 than that in the lowest tertile (p = 0.042). Additionally, higher levels of PCSK9 were found in poorly controlled group compared with the well-controlled group (p = 0.029). CONCLUSIONS: Data suggest a positive correlation of PCSK9 levels with HbA1c in patients with T2DM but not in patients without T2DM, indicating a potential role of PCSK9 in T2DM. Copyright © 2015 John Wiley & Sons, Ltd.

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.

[PCSK9 inhibition as the new hope for patients with familial hypercholesterolemia, statin intolerance and eventually for those at the highest cardiovascular risk? Focused on alirocumab, Praluent®]. / Inhibice PCSK9 jako nová nadeje pro nemocné s familiární hypercholesterolemií, statinovou intolerancí a posléze pro vsechny pacienty v nejvyssím kardiovaskulárním riziku? Zamereno na alirokumab--Praluent®.

At the present time there are novel hypolipidemics registered globally (alirocumab was the first drug of this group in the world registered by an American drug agency FDA) and in Europe, which in many ways differ from the medicines administered until now. They are bringing another advancement in the treatment of disorders of lipid metabolism and in preventive cardiology. Alirocumab is a fully human monoclonal antibody to PCSK-9 enzyme (proprotein convertase subtilisin kexin-9). PCSK-9 enzyme plays an important role in the metabolism of LDL-cholesterol through affecting the breakdown and eventually the amount and activity of LDL-receptors. From the clinical point of view it is essential that drugs from this group are administered parenterally, as a subcutaneous injection. In the case of Praluent® the interval between administration is two weeks. The dose is then 75 or 150 mg in a 1 ml injection. From the clinical point of view it is particularly important that alirocumab decreases LDL-C concentrations by 50-60%, it decreases Lp/a/ levels by 25-30%, and it also positively influences other components of lipid metabolism and, above all, is very likely to have a potential to decrease a cardiovascular risk. Although the resuIts of morbidity and mortality studies are expected in the coming years, initial analyses strongly indicate a clinically significant reduction of CV events. Alirocumab, Praluent can be administered as monotherapy (mainly to statin-intolerant patients), however it will be primarily administered in combination with the other hypolipidemic drugs (in particular statins) where the effort to reach target values has not succeeded.

Decreased PCSK9 expression in human hepatocellular carcinoma.

BACKGROUND: The management of hepatocellular carcinoma (HCC) is limited by the lack of adequate screening biomarkers and chemotherapy. In response, there has been much interest in tumor metabolism as a therapeutic target. PCSK9 stimulates internalization of the LDL-receptor, decreases cholesterol uptake into hepatocytes and affects liver regeneration. Thus, we investigated whether PCSK9 expression is altered in HCC, influencing its ability to harness cholesterol metabolism. METHODS: Thirty-nine patients undergoing partial hepatectomy or liver transplantation for HCC were consented for use of HCC tissue to construct a tissue microarray (TMA). The TMA was immunostained for PCSK9. Imagescope software was used to objectively determine staining, and assess for pathological and clinical correlations. PCSK9 and LDL receptor mRNA levels in flash-frozen HCC and adjacent liver tissue were determined by quantitative RT-PCR. Serum PCSK9 levels were determined by ELISA. RESULTS: By immunohistochemistry, there was significantly lower expression of PCSK9 in HCC as compared to adjacent cirrhosis (p-value < 0.0001, wilcoxon signed-rank test). Significantly greater staining of PCSK9 was present in cirrhosis compared to HCC (p value <0.0001), and positivity (percentage of positive cells) was significantly greater in cirrhosis compared to HCC (p-value < 0.0001). Conversely, significantly higher expression of LDL-R was present in HCC as compared to the adjacent cirrhosis (p-value < 0.0001). There was no significant correlation of PCSK9 staining with grade of tumor, but there were significant correlations between PCSK9 staining and stage of fibrosis, according to spearman correlation test. PCSK9 mRNA levels were relatively less abundant within HCC compared to adjacent liver tissue (p-value =0.08) and normal control tissue (p-value =0.02). In contrast, serum PCSK9 levels were significantly increased among patients with HCC compared to those with chronic liver disease without HCC (p-value =0.029). LDL receptor mRNA was consistantly greater in HCC when compared to normal control tissue (p-value = 0.06) and, in general, was significantly greater in HCC when compared to adjacent liver (p-value = 0.04). CONCLUSIONS: The decreased expression of PCSK9 and conversely increased LDL-R expression in HCC suggests that HCC modulates its local microenvironment to enable a constant energy supply. Larger-scale studies should be conducted to determine whether PCSK9 could be a therapeutic target for HCC.

Identification of PCSK9 as a novel serum biomarker for the prenatal diagnosis of neural tube defects using iTRAQ quantitative proteomics.

To identify candidate serum molecule biomarkers for the non-invasive early prenatal diagnosis of neural tube defects (NTDs), we employed an iTRAQ-based quantitative proteomic approach to analyze the proteomic changes in serum samples from embryonic day (E) 11 and E13 pregnant rats with spina bifida aperta (SBA) induced by all-trans retinoic acid. Among the 390 proteins identified, 40 proteins at E11 and 26 proteins at E13 displayed significant differential expression in the SBA groups. We confirmed 5 candidate proteins by ELISA. We observed the space-time expression changes of proprotein convertase subtilisin/kexin type 9 (PCSK9) at different stages of fetal development, including a marked decrease in the sera of NTD pregnancies and gradual increase in the sera of normal pregnancies with embryonic development. PCSK9 demonstrated the diagnostic efficacy of potential NTD biomarkers [with an area under the receiver operating characteristic curve of 0.763, 95% CI: 065-0.88]. Additionally, PCSK9 expression in the spinal cords and placentas of SBA rat fetuses was markedly decreased. PCSK9 could serve as a novel molecular biomarker for the non-invasive prenatal screening of NTDs and may be involved in the pathogenesis of NTDs at critical periods of fetal development.

Proprotein Convertase Subtilisin/Kexin type 9, C-Reactive Protein, Coronary Severity, and Outcomes in Patients With Stable Coronary Artery Disease: A Prospective Observational Cohort Study.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is suggested as a novel factor associated with coronary artery disease (CAD). However, few studies have comprehensively evaluated plasma PCSK9 with cardiovascular risk till now. Hence, we aimed to prospectively investigate the association between baseline PCSK9 and cardiovascular risk graded with number of risk factors (RFs), coronary severity, and outcomes in patients with stable CAD.Baseline characteristics and biomarkers were measured in 616 consecutive, nontreated patients with stable CAD. Coronary severity was measured using SYNTAX, Gensini, and Jeopardy scoring systems. Patients were then received treatment and followed for a median of 17 months. The primary endpoints were cardiac death, stroke, myocardial infarction (MI), post-discharge revascularization, or unstable angina (UA).Overall, follow-up data were obtained from 603 patients. A total of 72 (11.9%) patients presented with at least 1 major adverse cardiovascular event (MACE) (4 cardiac deaths, 4 strokes, 6 MIs, 28 revascularizations, and 30 UAs). At baseline, PCSK9 was increased with an increasing number of RFs and positively associated with coronary severity scores (P < 0.05, all). After follow-up, those with MACE had a higher baseline PCSK9, hs-CRP, and coronary scores than those without (P < 0.05, all). Multivariate analysis showed that PCSK9, hs-CRP, and coronary scores were independently predictive for MACEs (P < 0.05, all). Interestingly, more significant predictive values of PCSK9 in medical-alone-treated population but no such associations in revascularization-treated patients were found.Together, plasma PCSK9, as well as hs-CRP and coronary scores, could independently predict MACEs in patients with stable CAD.

The associations between proprotein convertase subtilisin/kexin type 9 E670G polymorphism and the risk of coronary artery disease and serum lipid levels: a meta-analysis.

BACKGROUND: Studies had investigated the associations between proprotein convertase subtilisin/kexin type 9 (PCSK9) E670G polymorphism and coronary artery disease (CAD) and lipid levels, but the results were controversial. Thus, we performed this meta-analysis to investigate the association between PCSK9 E670G polymorphism and lipid levels and the susceptibility to CAD. METHODS: All relevant articles according to the inclusion criteria were retrieved and included in the present meta-analysis. Odds ratios (ORs) with 95 % confidence interval (CI) were used to analyze the strength of the association between PCSK9 E670G polymorphism and the susceptibility to CAD. At the same time, the pooled standardized mean difference (SMD) with 95 % CI was used for the meta-analysis of PCSK9 E670G polymorphism and lipid levels. The publication bias was examined by using Begg's funnel plots and Egger's test. RESULTS: A total of seventeen studies met the inclusion criteria. For CAD association, the pooled effects indicated that the G allele carriers had higher risk of CAD than non-carriers in dominant genetic model (OR:1.601, 95 % CI: 1.314-1.951, P < 0.001), as well as in allelic genetic model (OR: 1.546, 95 % CI: 1.301-1.838, P < 0.001). When the subgroup analysis stratified by ethnicity and HWE was performed, the positive result existed in most of the subgroups. For lipid levels association, the pooled effects indicated that the G allele carriers had higher TC and LDL-C levels than the non-carriers (for TC, SMD: 0.126, 95 % CI: 0.023-0.229, P = 0.016; for LDL-C, SMD: 0.170, 95 % CI: 0.053-0.287, P = 0.004, respectively). There was no difference in the levels of TG and HDL-C between the G carriers and the non-carriers in the whole population (SMD: 0.031, 95 % CI: -0.048-0.110, P = 0.440; SMD: -0.123, 95 % CI: -0.251-0.006, P = 0.061, respectively). When the studies were stratified by ethnicity and type of study, the G carriers had higher TC levels than the non-carriers (SMD: 0.126, 95 % CI: 0.014-0.238, P = 0.027) in the non-Asian subgroup. The similar results existed in cohort subgroup. The association between PCSK9 E670G polymorphism and LDL-C levels was significant in all subgroups. Meanwhile, the G carriers had higher TG levels than the non-carriers (SMD: 0.113, 95 % CI: 0.012-0.214, P = 0.028) in the case-control subgroup. AG + GG genotypes had lower HDL-C levels than AA genotype in Asian subgroup (SMD: -0.224, 95 % CI: -0.423- -0.025, P = 0.027) and in case-control subgroup (SMD: -0.257, 95 % CI: -0.467--0.048, P = 0.016). CONCLUSIONS: The present meta-analysis concluded that PCSK9 E670G polymorphism was associated with CAD risk and lipid levels.

New Approaches in Detection and Treatment of Familial Hypercholesterolemia.

Familial hypercholesterolemia (FH) is an autosomal dominant genetic disorder that clinically leads to increased low density lipoprotein-cholesterol (LDL-C) levels. As a consequence, FH patients are at high risk for cardiovascular disease (CVD). Mutations are found in genes coding for the LDLR, apoB, and PCSK9, although FH cannot be ruled out in the absence of a mutation in one of these genes. It is pivotal to diagnose FH at an early age, since lipid lowering results in a decreased risk of cardiovascular complications especially if initiated early, but unfortunately FH is largely underdiagnosed. While a number of clinical criteria are available, identification of a pathogenic mutation in any of the three aforementioned genes is seen by many as a way to establish a definitive diagnosis of FH. It should be remembered that clinical treatment is based on LDL-C levels and not solely on presence or absence of genetic mutations as LDL-C is what drives risk. Traditionally, mutation detection has been done by means of dideoxy sequencing. However, novel molecular testing methods are gradually being introduced. These next generation sequencing-based methods are likely to be applied on broader scale once their efficacy and effect on cost are being established. Statins are the first-line therapy of choice for FH patients as they have been proven to reduce CVD risk across a range of conditions including hypercholesterolemia (though not specifically tested in FH). However, in a significant proportion of FH patients LDL-C goals are not met, despite the use of maximal statin doses and additional lipid-lowering therapies. This underlines the need for additional therapies, and inhibition of PCSK9 and CETP is among the most promising new therapeutic options. In this review, we aim to provide an overview of the latest information about the definition, diagnosis, screening, and current and novel therapies for FH.

Proprotein convertase subtilisin/kexin type 9 (PCSK9), soluble lectin-like oxidized LDL receptor 1 (sLOX-1) and ankle brachial index in patients with differentiated thyroid cancer.

The cardiovascular effects of short-term overt hypothyroidism are not well known. We investigated proprotein convertase subtilisin/kexin type 9 (PCSK9), soluble lectin-like oxidized LDL receptor 1 (sLOX-1) and the ankle brachial index (ABI) in thyroid cancer patients with short-term overt hypothyroidism due to thyroid hormone withdrawal (THW). Twenty-one patients requiring radioactive iodine (RAI) ablation or scanning and 36 healthy control subjects were enrolled. Patients were evaluated in the subclinical thyrotoxic phase when they were on suppressive levothyroxine therapy and in the overt hypothyroid phase due to THW for four weeks. PCSK9, sLOX-1, lipids and ABI were measured in the patient and control groups. Total cholesterol, LDL cholesterol, triglycerides and Apo B levels were increased in short overt hypothyroidism compared with the control group (p<0.001). PCSK9 levels increased before THW and after THW in the patients compared to control group (p<0.001, p=0.004, respectively). sLOX-1 levels were not different between patients with short term overt hypothyroidism and control group (p=0.27). ABI was found to be significantly decreased in patients with thyroid cancer before and after THW compared to control group (p=0.04, p=0.002 respectively). PCSK9 levels were correlated negatively with ABI (r=-0.38, p=0.004). In conclusion; our study demonstrated that patients with differentiated thyroid cancer both before and after THW which is a short term overt hypothyroid phase, had increased PCSK9 levels and decreased ABI. Short term overt hypothyroidism also leads to increased HDL, LDL, total cholesterol, Apo A and Apo B levels.

Focus on alirocumab: A PCSK9 antibody to treat hypercholesterolemia.

Statin treatment represents the gold standard in the reduction of low-density lipoprotein cholesterol and cardiovascular risk. Although statin therapy is generally well tolerated, some patients fail to achieve the target level of low-density lipoprotein cholesterol or discontinue the treatment for the occurrence of adverse events. In recent years new lipid-modifying agents have been studied to overcome these limitations and to reduce low-density lipoprotein cholesterol plasma levels. Alirocumab is a fully human monoclonal antibody that inhibits proprotein convertase subtilisin/kexin type 9, thereby preventing its interaction with low density lipoprotein receptors. Several trials have been conducted in the last few years to evaluate long-term effects of this new molecule on low-density lipoprotein cholesterol levels and cardiovascular risk.

Anacetrapib reduces (V)LDL cholesterol by inhibition of CETP activity and reduction of plasma PCSK9.

Recently, we showed in APOE*3-Leiden cholesteryl ester transfer protein (E3L.CETP) mice that anacetrapib attenuated atherosclerosis development by reducing (V)LDL cholesterol [(V)LDL-C] rather than by raising HDL cholesterol. Here, we investigated the mechanism by which anacetrapib reduces (V)LDL-C and whether this effect was dependent on the inhibition of CETP. E3L.CETP mice were fed a Western-type diet alone or supplemented with anacetrapib (30 mg/kg body weight per day). Microarray analyses of livers revealed downregulation of the cholesterol biosynthesis pathway (P < 0.001) and predicted downregulation of pathways controlled by sterol regulatory element-binding proteins 1 and 2 (z-scores -2.56 and -2.90, respectively; both P < 0.001). These data suggest increased supply of cholesterol to the liver. We found that hepatic proprotein convertase subtilisin/kexin type 9 (Pcsk9) expression was decreased (-28%, P < 0.01), accompanied by decreased plasma PCSK9 levels (-47%, P < 0.001) and increased hepatic LDL receptor (LDLr) content (+64%, P < 0.01). Consistent with this, anacetrapib increased the clearance and hepatic uptake (+25%, P < 0.001) of [(14)C]cholesteryl oleate-labeled VLDL-mimicking particles. In E3L mice that do not express CETP, anacetrapib still decreased (V)LDL-C and plasma PCSK9 levels, indicating that these effects were independent of CETP inhibition. We conclude that anacetrapib reduces (V)LDL-C by two mechanisms: 1) inhibition of CETP activity, resulting in remodeled VLDL particles that are more susceptible to hepatic uptake; and 2) a CETP-independent reduction of plasma PCSK9 levels that has the potential to increase LDLr-mediated hepatic remnant clearance.

The apoB-to-PCSK9 ratio: A new index for metabolic risk in humans.

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) shuttles low-density lipoprotein (LDL) receptors for degradation, thus upregulates LDL plasma clearance. Although PCSK9 loss of function is cardioprotective, its role in metabolic risks remains unknown. Increased apoB-lipoproteins uptake into nonhepatic tissues such as white adipose tissue (WAT) induces their dysfunction, which may be favored by lower plasma PCSK9. We hypothesized that lower plasma PCSK9 relative to apoB, or higher apoB-to-PCSK9 ratio, is a better predictor of metabolic disturbances than PCSK9 alone in humans. METHODS: Thirty-three men and 48 postmenopausal women (>27 kg/m(2), aged 45-74 years, normoglycemic) underwent in-depth assessment of glucose and fat metabolism using high-fat meals, WAT biopsies, intravenous glucose-tolerance tests, and hyperinsulinemia clamps. RESULTS: Plasma apoB correlated positively with fasting and postprandial triglycerides and chylomicron clearance (R = 0.44-0.66) and glucose-stimulated insulin secretion (R = 0.24) and negatively with insulin sensitivity (R = -0.28) and gynoid WAT in situ lipoprotein lipase activity (ie, ex vivo WAT function, R(2) = 0.34). Neither PCSK9 nor LDL cholesterol associated with these risks. In regression analysis that adjusted for body mass index, lower plasma PCSK9 strengthened the association of apoB to WAT dysfunction and insulin resistance. Moreover, plasma apoB-to-PCSK9 ratio correlated positively with all these metabolic risks and further associated positively with android-to-gynoid fat ratio (R = 0.41) and negatively with gynoid fat mass (R = -0.23, all P ≤ .05). No significant sex differences existed in these associations. CONCLUSIONS: Lower plasma PCSK9 relative to apoB associates with metabolic risks and WAT dysfunction in normoglycemic obese subjects. We hypothesize that the plasma apoB-to-PCSK9 ratio provides a better clinical index than PCSK9 alone for monitoring early metabolic disturbances that may be promoted by reduction in plasma PCSK9.

PCSK9 deficiency unmasks a sex- and tissue-specific subcellular distribution of the LDL and VLDL receptors in mice.

Proprotein convertase subtilisin kexin type 9 (PCSK9), the last member of the family of Proprotein Convertases related to Subtilisin and Kexin, regulates LDL-cholesterol by promoting the endosomal/lysosomal degradation of the LDL receptor (LDLR). Herein, we show that the LDLR cell surface levels dramatically increase in the liver and pancreatic islets of PCSK9 KO male but not female mice. In contrast, in KO female mice, the LDLR is more abundant at the cell surface enterocytes, as is the VLDL receptor (VLDLR) at the cell surface of adipocytes. Ovariectomy of KO female mice led to a typical KO male pattern, whereas 17ß-estradiol (E2) treatment restored the female pattern without concomitant changes in LDLR adaptor protein 1 (also known as ARH), disabled-2, or inducible degrader of the LDLR expression levels. We also show that this E2-mediated regulation, which is observed only in the absence of PCSK9, is abolished upon feeding the mice a high-cholesterol diet. The latter dramatically represses PCSK9 expression and leads to high surface levels of the LDLR in the hepatocytes of all sexes and genotypes. In conclusion, the absence of PCSK9 results in a sex- and tissue-specific subcellular distribution of the LDLR and VLDLR, which is determined by E2 levels.

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

AIM: Recent 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. METHODS: Plasma 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. RESULTS: Plasma 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. CONCLUSION: Lp(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.

The Central Role of Proprotein Convertase Subtilisin/Kexin Type 9 in Septic Pathogen Lipid Transport and Clearance.

Microbial cell walls contain pathogenic lipids, including LPS in gram-negative bacteria, lipoteichoic acid in gram-positive bacteria, and phospholipomannan in fungi. These pathogen lipids are major ligands for innate immune receptors and figure prominently in triggering the septic inflammatory response. Alternatively, pathogen lipids can be cleared and inactivated, thus limiting the inflammatory response. Accordingly, biological mechanisms for sequestering and clearing pathogen lipids from the circulation have evolved. Pathogen lipids released into the circulation are initially bound by transfer proteins, notably LPS binding protein and phospholipid transfer protein, and incorporated into high-density lipoprotein particles. Next, LPS binding protein, phospholipid transfer protein, and other transfer proteins transfer these lipids to ApoB-containing lipoproteins, including low-density (LDL) and very-low-density lipoproteins and chylomicrons. Pathogen lipids within these lipoproteins and their remnants are then cleared from the circulation by the liver. Hepatic clearance involves the LDL receptor (LDLR) and possibly other receptors. Once absorbed by the liver, these lipids are then excreted in the bile. Recent evidence suggests pathogen lipid clearance can be modulated. Importantly, reduced proprotein convertase subtilisin/kexin type 9 activity increases recycling of the LDLR and thereby increases LDLR on the surface of hepatocytes, which increases clearance by the liver of pathogen lipids transported in LDL. Increased pathogen lipid clearance, which can be achieved by inhibiting proprotein convertase subtilisin/kexin type 9, may decrease the systemic inflammatory response to sepsis and improve clinical outcomes.