Plasma PCSK9 Levels Research Articles

Reduction of triglyceride-rich lipoproteins with retatrutide in type 2 diabetes may be explained by concurrent reduction in ANGPTL3/8 levels

Abstract Background/Introduction In the recent phase 2 study (NCT04867785) in patients with type 2 diabetes (T2D), retatrutide, an agonist of glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), and glucagon receptors, reduced triglycerides (TG) and non-high-density lipoprotein cholesterol (non-HDL-C) up to 35.0% and 20.7%, respectively. The angiopoietin-like 3/8 complex (ANGPTL3/8) is the most potent circulating inhibitor of lipoprotein lipase (LPL), and its serum levels have been shown to be directly correlated with TG and low-density lipoprotein cholesterol (LDL-C). Purpose In the aforementioned phase 2 study, we examined the effects of retatrutide on circulating ANGPTL3/8 complex concentrations to help understand the mechanism by which retatrutide reduced TG and non-HDL-C. Methods Patients with T2D were randomly assigned to receive once-weekly injections of placebo, 1.5 mg dulaglutide, or retatrutide doses of 0.5 mg, 4 mg, 8 mg, or 12 mg. Fasting serum samples were collected at baseline, week 2, week 4, week 8, week 12, week 16, and week 24, and ANGPTL3/8 levels were measured at all time points using a sensitive and selective immunoassay. Plasma PCSK9 levels were also measured at baseline and 24 weeks. Data were analyzed using a mixed model for repeated measures with log-transformation. Results Baseline ANGPTL3/8 levels (mean 26.3 ng/mL, IQR 17.4-33.0 ng/mL) were not different among all study groups. Mean percent changes of ANGPTL3/8 from baseline at week 24 were -1.3%, -12.0%, -48.7% and -51.0% in 0.5 mg, 4 mg, 8 mg and 12 mg retatrutide groups, respectively (Figure). Percent changes of ANGPTL3/8 in 8 mg and 12 mg retatrutide groups were significantly different from placebo group (p < 0.0001). Mean percent changes of PCSK9 levels from baseline to 24 weeks were not different from placebo for any treatment arm (+6.2%, -3.9%, -3.8% and -9.6% for retatrutide 0.5 mg, 4 mg, 8 mg and 12 mg groups, respectively, and -1.5% for dulaglutide and -6.5% for placebo). Conclusions In patients with T2D, retatrutide dose-dependently decreased serum concentrations of ANGPTL3/8, the most potent circulating LPL inhibitor. These data suggest that retatrutide may reduce TG-rich lipoproteins by decreasing ANGPTL3/8 levels.

Population pharmacokinetics of a novel PCSK9 antisense oligonucleotide.

The aim of this study was to characterize the population pharmacokinetics of AZD8233, an antisense oligonucleotide (ASO) that targets the PCSK9 transcript to reduce hepatocyte PCSK9 protein production and plasma levels. AZD8233 utilizes generation 2.5S-constrained ethyl motif (cET) chemistry and is conjugated to a triantennary N-acetylgalactosamine (GalNAc3) ligand for targeted hepatocyte uptake. A non-linear mixed-effect modelling approach utilizing NONMEM software was applied to AZD8233 concentration-time data from 3416 samples in 219 participants from four phase 1-2 studies, one in healthy volunteers (NCT03593785) and three in patients with dyslipidaemia (NCT04155645, NCT04641299 and NCT04823611). The final model described the AZD8233 plasma concentration-time profile from four phase 1-2 studies in healthy volunteers or participants with dyslipidaemia, covering a dose range of 4 to 120 mg. The pharmacokinetics of AZD8233 were adequately described by a two-compartment model with first-order absorption. The supra-proportional increase in maximum plasma concentration (Cmax) across the observed dose range was described by non-linear Michaelis-Menten elimination (maximum elimination rate, 9.9mg/h [12% relative standard error]; concentration yielding half-maximal elimination rate, 4.8mg/L [18% relative standard error]). Body weight, sex, estimated glomerular filtration rate and disease status (healthy participant vs. patient with dyslipidaemia) were identified as factors affecting exposure to AZD8233. Covariate analysis showed body weight to be the main factor affecting exposure to AZD8233, which largely explained the higher Cmax observed in the Asian population relative to non-Asians.

Plasma Protein Biomarkers Distinguish Multisystem Inflammatory Syndrome in Children From Other Pediatric Infectious and Inflammatory Diseases.

Multisystem inflammatory syndrome in children (MIS-C) is a rare but serious hyperinflammatory complication following infection with severe acute respiratory syndrome coronavirus 2. The mechanisms underpinning the pathophysiology of MIS-C are poorly understood. Moreover, clinically distinguishing MIS-C from other childhood infectious and inflammatory conditions, such as Kawasaki disease or severe bacterial and viral infections, is challenging due to overlapping clinical and laboratory features. We aimed to determine a set of plasma protein biomarkers that could discriminate MIS-C from those other diseases. Seven candidate protein biomarkers for MIS-C were selected based on literature and from whole blood RNA sequencing data from patients with MIS-C and other diseases. Plasma concentrations of ARG1, CCL20, CD163, CORIN, CXCL9, PCSK9 and ADAMTS2 were quantified in MIS-C (n = 22), Kawasaki disease (n = 23), definite bacterial (n = 28) and viral (n = 27) disease and healthy controls (n = 8). Logistic regression models were used to determine the discriminatory ability of individual proteins and protein combinations to identify MIS-C and association with severity of illness. Plasma levels of CD163, CXCL9 and PCSK9 were significantly elevated in MIS-C with a combined area under the receiver operating characteristic curve of 85.7% (95% confidence interval: 76.6%-94.8%) for discriminating MIS-C from other childhood diseases. Lower ARG1 and CORIN plasma levels were significantly associated with severe MIS-C cases requiring inotropes, pediatric intensive care unit admission or with shock. Our findings demonstrate the feasibility of a host protein biomarker signature for MIS-C and may provide new insight into its pathophysiology.

Extracellular vesicle-mediated delivery of CRISPR/Cas9 ribonucleoprotein complex targeting proprotein convertase subtilisin-kexin type 9 (Pcsk9) in primary mouse hepatocytes.

The loss-of-function of the proprotein convertase subtilisin-kexin type 9 (Pcsk9) gene has been associated with significant reductions in plasma serum low-density lipoprotein cholesterol (LDL-C) levels. Both CRISPR/Cas9 and CRISPR-based editor-mediated Pcsk9 inactivation have successfully lowered plasma LDL-C and PCSK9 levels in preclinical models. Despite the promising preclinical results, these studies did not report how vehicle-mediated CRISPR delivery inactivating Pcsk9 affected low-density lipoprotein receptor recycling in vitro or ex vivo. Extracellular vesicles (EVs) have shown promise as a biocompatible delivery vehicle, and CRISPR/Cas9 ribonucleoprotein (RNP) has been demonstrated to mediate safe genome editing. Therefore, we investigated EV-mediated RNP targeting of the Pcsk9 gene ex vivo in primary mouse hepatocytes. We engineered EVs with the rapamycin-interacting heterodimer FK506-binding protein (FKBP12) to contain its binding partner, the T82L mutant FKBP12-rapamycin binding (FRB) domain, fused to the Cas9 protein. By integrating the vesicular stomatitis virus glycoprotein on the EV membrane, the engineered Cas9 EVs were used for intracellular CRISPR/Cas9 RNPdelivery, achieving genome editing with an efficacy of ±28.1% in Cas9 stoplight reporter cells. Administration of Cas9 EVs in mouse hepatocytes successfully inactivated the Pcsk9 gene, leading to a reduction in Pcsk9 mRNA and increased uptake of the low-density lipoprotein receptor and LDL-C. These readouts can be used in future experiments to assess the efficacy of vehicle-mediated delivery of genome editing technologies targeting Pcsk9. The ex vivo data could be a step towards reducing animal testing and serve as a precursor to future in vivo studies for EV-mediated CRISPR/Cas9 RNP delivery targeting Pcsk9.

Sirtuin-1 directly binds and deacetylates hepatic PCSK9 to inhibit low-density lipoprotein receptor degradation

Abstract Background Low-density lipoprotein cholesterol (LDL-C) is causally involved in atherosclerotic cardiovascular disease (ASCVD). We have previously shown that pharmacological activation of Sirtuin-1 (SIRT1), a NAD+-dependent deacetylase, reduces plasma LDL-C levels by decreasing PCSK9 and increasing hepatic LDLR expression, thus exerts atheroprotective effects in mice; however, the mechanism of SIRT1 action remains elusive. Purpose We found diminished levels of circulating SIRT1 in atherosclerotic mice compared to wild-type healthy controls. We hypothesized that this decrease in SIRT1 levels may promote dysregulated lipid metabolism and ASCVD in humans. Herein, we aimed to restore the reduced systemic Sirtuin-1 plasma levels in ASCVD by injecting recombinant murine Sirtuin-1 (rmSIRT1) in atherosclerotic mice. Methods Twelve-week-old apolipoprotein E-deficient (ApoE-/-) male mice fed a high-cholesterol diet (1.25% w/w) were randomized to receive rmSIRT1 (n=6; 0.3mg/kg BW i.p.) or vehicle treatment (n=6) every third day over 4-weeks. Mice were euthanized and organs were harvested to study lipid metabolism and ASCVD progression. Human hepatocytes (Huh7) cells were used to perform radioactive assays to study cellular uptake of radioiodinated LDL, surface plasmon resonance to study binding and site-directed mutagenesis to dissect the underlying molecular mechanism exerted by circulating SIRT1. Results Boosting circulating SIRT1 levels increased hepatic LDLR expression, reduced plasma LDL-C levels and progression of plaques in ApoE-/- mice (Figure 1). rmSIRT1 treatment did not change hepatic expression of total PCSK9 but increased its deacetylated status. Mechanistically, rmSIRT1 directly bound to hepatic PCSK9 and deacetylated PCSK9 at 3 sites: Lys243, Lys421 and Lys506 as shown by Surface Plasmon Resonance and mass spectrometry, respectively. In vitro mutagenesis to triple deacetylation mimetic (3KR) in hepatocytes (Huh7 cells) reduced SIRT1-induced PCSK9 activity, as evidenced by increased cellular binding and association of 125I-LDL through LDLR in Huh7cells. Finally, plasma levels of SIRT1 and PCSK9 were assessed at baseline in patients with acute coronary syndromes (ACS) where plasma SIRT1 showed an inverse correlation with PCSK9 and conferred a reduced risk of major adverse cardiovascular events. Conclusion SIRT1 directly binds PCSK9 and decreases its activity by deacetylation, thereby enhancing LDL-C clearance by hepatic LDLR upregulation. Increased circulating SIRT1 exerts atheroprotective effects and is associated with improved prognosis in patients with ACS.Figure 1

Exploring PCSK9 Genetic Impact on Lipoprotein(a) via Dual Approaches: Association and Mendelian Randomization.

Previous investigations have suggested an association between the PCSK9 common polymorphism E670G and Lipoprotein(a) (Lp(a)) levels, as well as a link between plasma PCSK9 levels and Lp(a) concentrations. However, the causal relationship between plasma PCSK9 and Lp(a) levels remains uncertain. In this study, we explored the association between PCSK9 E670G polymorphism and Lp(a) levels in 614 healthy Taiwanese individuals. Employing a two-sample Mendelian randomization (MR) analysis using openly accessible PCSK9 and Lp(a) summary statistics from the genome-wide association studies (GWAS) and UK Biobank, we aimed to determine if a causal link exists between plasma PCSK9 levels and Lp(a) concentrations. Our findings reveal that the E670G G allele is independently associated with a decreased likelihood of developing elevated Lp(a) levels. This association persists even after adjusting for common cardiovascular risk factors and irrespective of lipid profile variations. The MR analysis, utilizing six PCSK9 GWAS-associated variants as instrumental variables to predict plasma PCSK9 levels, provides compelling evidence of a causal relationship between plasma PCSK9 levels and Lp(a) concentration. In conclusion, our study not only replicates the association between the PCSK9 E670G polymorphism and Lp(a) levels but also confirms a causative relationship between PCSK9 levels and Lp(a) concentrations through MR analysis.

A case of hypocholesterolemia under research

Primary hypocholesterolemia (or hypobetalipoproteinemia) is a rare disorder of lipoprotein metabolism that may be due to a polygenic predisposition or a monogenic disease. Among these, it is possible to differentiate between symptomatic and asymptomatic forms, in which, in the absence of secondary causes, the initial clinical suspicion is plasma ApoB levels below the 5th percentile of the distribution by age and sex. Here we describe the differential diagnosis of a case of asymptomatic hypocholesterolemia. We studied proband’s clinical data, the lipid profile of the proband and her relatives and the clinical data of the family relevant to carry out the differential diagnosis. We performed a genetic study as the diagnostic test. The information obtained from the differential diagnosis suggested a heterozygous hypobetalipoproteinemia due to PCSK9 loss-of-function variants. The diagnostic test revealed, in the proband, the presence of a heterozygous PCSK9 frame-shift variant of a maternal origin. Plasma levels of LDL cholesterol and PCSK9 of the patient and her relatives were compatible with the segregation of the variant revealed. In conclusion, the diagnostic test performed confirmed the suspected diagnosis of the proband as asymptomatic familial hypobetalipoproteinemia due to a loss-of-function variant in the PCSK9 gene.

Correlation between Plasma PCSK9 and Blood Lipids in Patients with Newly Diagnosed Primary Nephrotic Syndrome

Abstract Background Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a major post-transcriptional regulator of low-density lipoprotein receptor degradation. Recently, PCSK9 was shown to be overexpressed by liver cells in rats with proteinuria. However, the levels of PCSK9 in newly diagnosed primary nephrotic syndrome (PNS) patients and correlations involving PCSK9 and blood lipids are not clearly understood. Aim of the Work The aim of this study is to assess the association between plasma pcsk 9 and blood lipids in patients with newly diagnosed primary nephrotic syndrome Patients and Methods This was a case control study in Ain Shams University hospital for 4 months on 50 patients, 35 control. Results in our study elevated plasma PCSK9 levels had a positive linear correlation with elevated serum TC (p value <0.001) and LDL-C (p value <0.001), triglycerides (p value 0.003), HDL (p value 0.012), VLDL(p value 0.001) A comparison of plasma PCSK9 levels of MCD, MN And primary focal segmental patients showed that they were not significantly different (p value 0.954). In our study, we found that the plasma levels of pcsk9 were significantly higher than in healthy controls 314.580 ± 73.835 ng/ml vs 253.429 ±36.666, and this difference was statistically significant P-value <0.001. In our study plasma PCSK9 levels in patients with PNS had no linear correlation with the amount of proteinuria per 24 h, p value 0.070 or with albumin p value 0.549 and there was no statistical difference between the the two groups of proteinuria (3.5-8 (g)/24 h vs > 8 (g)/24 h) p value 0.378. Conclusion Plasma PCSK9 levels in newly diagnosed primary nephrotic patients were markedly increased and positively correlated with total cholesterol, VLDL, LDL, HDL. suggesting that PCSK9 may emerge as a novel therapeutic target in nephrotic syndrome associated hypercholesterolemia

Small molecule inhibitors of PCSK9. SAR investigations of head and amine groups

Our previous work on the optimization of a new class of small molecule PCSK9 mRNA translation inhibitors focused on empirical optimization of the amide tail region of the lead PF-06446846 (1). This work resulted in compound 3 that showed an improved safety profile. We hypothesized that this improvement was related to diminished binding of 3 to non-translating ribosomes and an apparent improvement in transcript selectivity. Herein, we describe our efforts to further optimize this series of inhibitors through modulation of the heterocyclic head group and the amine fragment. Some of the effort was guided by an emerging cryo electron microscopy structure of the binding mode of 1 in the ribosome. These efforts led to the identification of 15 that was deemed suitable for evaluation in a humanized PCSK9 mouse model and a rat toxicology study. Compound 15 demonstrated a dose dependent reduction of plasma PCSK9 levels. The rat toxicological profile was not improved over that of 1, which precluded 15 from further consideration as a clinical candidate.

Un caso de hipocolesterolemia a estudio

Primary hypocholesterolemia (or hypobetalipoproteinemia) is a rare disorder of lipoprotein metabolism that may be due to a polygenic predisposition or a monogenic disease. Among these, it is possible to differentiate between symptomatic and asymptomatic forms, in which, in the absence of secondary causes, the initial clinical suspicion is plasma ApoB levels below the 5th percentile of the distribution by age and sex. Here we describe the differential diagnosis of a case of asymptomatic hypocholesterolemia. We studied proband's clinical data, the lipid profile of the proband and her relatives and the clinical data of the family relevant to carry out the differential diagnosis. We performed a genetic study as the diagnostic test. The information obtained from the differential diagnosis suggested a heterozygous hypobetalipoproteinemia due to PCSK9 loss-of-function variants. The diagnostic test revealed, in the proband, the presence of a heterozygous PCSK9 frame-shift variant of a maternal origin. Plasma levels of LDL cholesterol and PCSK9 of the patient and her relatives were compatible with the segregation of the variant revealed. In conclusion, the diagnostic test performed confirmed the suspected diagnosis of the proband as asymptomatic familial hypobetalipoproteinemia due to a loss-of-function variant in the PCSK9 gene.

Association between genetically proxied PCSK9 inhibition and prostate cancer risk: A Mendelian randomisation study.

Prostate cancer (PrCa) is the second most prevalent malignancy in men worldwide. Observational studies have linked the use of low-density lipoprotein cholesterol (LDL-c) lowering therapies with reduced risk of PrCa, which may potentially be attributable to confounding factors. In this study, we performed a drug target Mendelian randomisation (MR) analysis to evaluate the association of genetically proxied inhibition of LDL-c-lowering drug targets on risk of PrCa. Single-nucleotide polymorphisms (SNPs) associated with LDL-c (P < 5 × 10-8) from the Global Lipids Genetics Consortium genome-wide association study (GWAS) (N = 1,320,016) and located in and around the HMGCR, NPC1L1, and PCSK9 genes were used to proxy the therapeutic inhibition of these targets. Summary-level data regarding the risk of total, advanced, and early-onset PrCa were obtained from the PRACTICAL consortium. Validation analyses were performed using genetic instruments from an LDL-c GWAS conducted on male UK Biobank participants of European ancestry (N = 201,678), as well as instruments selected based on liver-derived gene expression and circulation plasma levels of targets. We also investigated whether putative mediators may play a role in findings for traits previously implicated in PrCa risk (i.e., lipoprotein a (Lp(a)), body mass index (BMI), and testosterone). Applying two-sample MR using the inverse-variance weighted approach provided strong evidence supporting an effect of genetically proxied inhibition of PCSK9 (equivalent to a standard deviation (SD) reduction in LDL-c) on lower risk of total PrCa (odds ratio (OR) = 0.85, 95% confidence interval (CI) = 0.76 to 0.96, P = 9.15 × 10-3) and early-onset PrCa (OR = 0.70, 95% CI = 0.52 to 0.95, P = 0.023). Genetically proxied HMGCR inhibition provided a similar central effect estimate on PrCa risk, although with a wider 95% CI (OR = 0.83, 95% CI = 0.62 to 1.13, P = 0.244), whereas genetically proxied NPC1L1 inhibition had an effect on higher PrCa risk with a 95% CI that likewise included the null (OR = 1.34, 95% CI = 0.87 to 2.04, P = 0.180). Analyses using male-stratified instruments provided consistent results. Secondary MR analyses supported a genetically proxied effect of liver-specific PCSK9 expression (OR = 0.90 per SD reduction in PCSK9 expression, 95% CI = 0.86 to 0.95, P = 5.50 × 10-5) and circulating plasma levels of PCSK9 (OR = 0.93 per SD reduction in PCSK9 protein levels, 95% CI = 0.87 to 0.997, P = 0.04) on PrCa risk. Colocalization analyses identified strong evidence (posterior probability (PPA) = 81.3%) of a shared genetic variant (rs553741) between liver-derived PCSK9 expression and PrCa risk, whereas weak evidence was found for HMGCR (PPA = 0.33%) and NPC1L1 expression (PPA = 0.38%). Moreover, genetically proxied PCSK9 inhibition was strongly associated with Lp(a) levels (Beta = -0.08, 95% CI = -0.12 to -0.05, P = 1.00 × 10-5), but not BMI or testosterone, indicating a possible role for Lp(a) in the biological mechanism underlying the association between PCSK9 and PrCa. Notably, we emphasise that our estimates are based on a lifelong exposure that makes direct comparisons with trial results challenging. Our study supports a strong association between genetically proxied inhibition of PCSK9 and a lower risk of total and early-onset PrCa, potentially through an alternative mechanism other than the on-target effect on LDL-c. Further evidence from clinical studies is needed to confirm this finding as well as the putative mediatory role of Lp(a).

A cVLP-Based Vaccine Displaying Full-Length PCSK9 Elicits a Higher Reduction in Plasma PCSK9 Than Similar Peptide-Based cVLP Vaccines.

Administration of PCSK9-specific monoclonal antibodies, as well as peptide-based PCSK9 vaccines, can lower plasma LDL cholesterol by blocking PCSK9. However, these treatments also cause an increase in plasma PCSK9 levels, presumably due to the formation of immune complexes. Here, we utilize a versatile capsid virus-like particle (cVLP)-based vaccine platform to deliver both full-length (FL) PCSK9 and PCSK9-derived peptide antigens, to investigate whether induction of a broader polyclonal anti-PCSK9 antibody response would mediate more efficient clearance of plasma PCSK9. This head-to-head immunization study reveals a significantly increased capacity of the FL PCSK9 cVLP vaccine to opsonize and clear plasma PCSK9. These findings may have implications for the design of PCSK9 and other vaccines that should effectively mediate opsonization and immune clearance of target antigens.

ODP557 PCSK9 Level Correlated with Disease Progression in Patient with Non-small Cell Lung Cancer

Abstract Background Hyperlipidemia may be present in cancer patients despite their debilitated general condition. It has also been reported that several types of cancer cells produce PCSK9, and that in advanced non-small cell lung cancer, chemotherapy with immune checkpoint inhibitors is effective in cases with low PCSK9 levels. We administered PCSK9 inhibitor to patients with advanced non-small cell lung cancer with hyperlipidemia according to the indications for hyperlipidemia. Chemotherapy with immune checkpoint inhibitors was performed, the patient's condition and the level of PSCK9 were observed. CASE: A woman in her 60s underwent surgery for lung cancer in 2017. The pathological diagnosis of squamous cell carcinoma of the left lower bronchus and the postoperative diagnosis of pT2bN2M0 stage IIIA were confirmed. Adjuvant chemotherapy with CDDP and VNR was started after surgery for her, but in 2018, recurrence of pulmonary lymph nodes was confirmed by intrabronchial induced transbronchial needle aspiration. The immunostaining result for PD-L1 was 50%. The first-line chemotherapy, the immune checkpoint inhibitor pembrolizumab, was started but was ineffective. She had high serum LDL levels of 174 mg/dL and high serum PCSK9 levels of 471 ng /mL (Norm: 47.4-225.2 ng/mL) despite exhaustion during her lung cancer treatment process. Her plasma PCSK9 levels were correlated with lung cancer status, suggesting PCSK9 production in lung cancer cells. Ezetimibe and statins were also discontinued because they were reported to increase serum PCSK9. The PCSC9K inhibitor evolocumab was administered at 140 mg every 2 weeks. Three months after the start of evolocumab, her serum PCSK9 level decreased slightly to 441 ng /mL. The immune checkpoint inhibitor nivolumab was then started, but the chemotherapy was ineffective, and her general condition worsened, correlating with her serum PCSK9 levels rising to 1635 ng/mL, and she died in 2021. Discussion and Clinical Lessons This is the first report on the clinical course of non-small cell lung cancer and the course of serum PCSK9 and the administration of PCSK9 inhibitors. Although PSCK9 is thought to be involved in cancer progression, the use of PCSK9 inhibitors at the same doses and doses as in the treatment of conventional hyperlipidemia failed to control cancer progression. The anti-PCSK9 vaccine has been experimentally shown to be effective against tumor progression. It is expected that PCSK9 inhibition by various methods will bring good results for cancer patients. Further research is needed to elucidate the exact mechanism by which PCSK9 regulates cancer cell proliferation and apoptosis. PCSK9 inhibitors, initially developed to treat hypercholesterolemia, may have significant involvement in the treatment of various cancers and their metastases. Therefore, collaboration between endocrinologists and oncologists is important in the laboratory and clinical practice. Presentation: No date and time listed

Independent association of PCSK9 with platelet reactivity in subjects without statin or antiplatelet agents.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) levels could predict cardiovascular event in patients with well-controlled LDL-C levels, suggesting an LDL-independent mechanism of PCSK9 on the cardiovascular system. Accumulating evidence suggests PCSK9 might be associated with increased platelet reactivity. This study aimed to assess the relationship between PCSK9 levels and platelet reactivity in subjects not taking statins or antiplatelet agents. A cross-sectional study was conducted to investigate the independent contribution of PCSK9 to platelet activity by controlling for the potential confounding factors. The study population included 89 subjects from a health examination centre who underwent routine annual health check-ups or had an examination before a selective operation. Subjects taking statins or antiplatelet agents were excluded. Adenosine diphosphate (ADP)-induced platelet aggregation was determined by PL-11 platelet analyzer using impedance aggregometry and plasma PCSK9 levels were determined using an ELISA. Serum Lipid profile was assessed by measuring the concentration of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG), with low-density lipoprotein cholesterol (LDL-C) being directly measured using enzymatic techniques. The association between PCSK9 and platelet reactivity was investigated. The study subjects were composed of 53 males and 36 females with an average age of 55 (±11) years old. The univariate correlation analysis showed significant correlation between ADP-induced maximal aggregation rate (MAR) and PCSK9 (r = 0.55, p < 0.001) as well as TC (r = 0.23, p = 0.028), LDL-C (r = 0.27, p < 0.001), and PLT (r = 0.31, p = 0.005). Being male (41.2% vs. 46.6, p = 0.04) and smoking (37.4 vs. 46.2%, p = 0.016) were associated with lower ADP-induced MAR than being female and non-smoking. However, there is no correlation between PCSK9 and AA-induced platelet maximal aggregation rate (r = 0.17, p = 0.12). Multiple regression analysis suggested that PCSK9 contributed independently to ADP-induced maximal aggregation rate (β = 0.08, p = 0.004) after controlling for the effect of TC, LDL-C, PLT, being male, and smoking. PCSK9 is positively associated with platelet reactivity, which may partly account for the beneficial effect of PCSK9 inhibition in reducing the risk of major adverse cardiovascular events after acute coronary syndrome (ACS).

Circulating levels of PCSK9, ANGPTL3 and Lp(a) in stage III breast cancers

Background / synopsisCholesterol and lipids play an important role in sustaining tumor growth and metastasis in a large variety of cancers. ANGPTL3 and PCSK9 modify circulating cholesterol levels, thus availability of lipids to peripheral cells. Little is known on the role, if any, of circulating lipid-related factors such as PCSK9, ANGPTL3 and lipoprotein (a) in cancers.Objective/purposeTo compare circulating levels of PCSK9, ANGPTL3, and Lp(a) in women with stage III breast cancer versus women with premalignant or benign breast lesions.MethodsTwenty-three plasma samples from women diagnosed with a stage III breast cancer (ductal, lobular or mixed) were matched for age with twenty-three plasma samples from women bearing premalignant (stage 0, n = 9) or benign (n = 14) breast lesions. The lipid profile (Apo B, total cholesterol, HDL cholesterol and triglycerides levels) and Lp(a) were measured on a Roche Modular analytical platform, whereas LDL levels were calculated with the Friedewald formula. ANGPTL3 and PCSK9 plasma levels were quantitated by ELISA. All statistical analyses were performed using SAS software version 9.4.ResultsPCSK9 levels were significantly higher in women with stage III breast cancer compared to age-matched counterparts presenting a benign lesion (95.9 ± 27.1 ng/mL vs. 78.5 ± 19.3 ng/mL, p < 0.05, n = 14). Moreover, PCSK9 levels positively correlated with breast disease severity (benign, stage 0, stage III) (Rho = 0.34, p < 0.05, n = 46). In contrast, ANGPTL3 and Lp(a) plasma levels did not display any association with breast disease status and lipids did not correlate with disease severity.ConclusionIn this small cohort of 46 women, PCSK9 levels tended to increase with the severity of the breast disease. Given that PCSK9 plays an important role in maintaining cholesterolemia, and a potential role in tumor evasion, present results warrant further investigation into a possible association between PCSK9 levels and breast cancer severity in larger cohorts of women.

Hepatic inactivation of murine Surf4 results in marked reduction in plasma cholesterol.

PCSK9 negatively regulates low-density lipoprotein receptor (LDLR) abundance on the cell surface, leading to decreased hepatic clearance of LDL particles and increased levels of plasma cholesterol. We previously identified SURF4 as a cargo receptor that facilitates PCSK9 secretion in HEK293T cells (Emmer et al., 2018). Here, we generated hepatic SURF4-deficient mice (Surf4fl/fl Alb-Cre+) to investigate the physiologic role of SURF4 in vivo. Surf4fl/fl Alb-Cre+ mice exhibited normal viability, gross development, and fertility. Plasma PCSK9 levels were reduced by ~60% in Surf4fl/fl Alb-Cre+ mice, with a corresponding ~50% increase in steady state LDLR protein abundance in the liver, consistent with SURF4 functioning as a cargo receptor for PCSK9. Surprisingly, these mice exhibited a marked reduction in plasma cholesterol and triglyceride levels out of proportion to the partial increase in hepatic LDLR abundance. Detailed characterization of lipoprotein metabolism in these mice instead revealed a severe defect in hepatic lipoprotein secretion, consistent with prior reports of SURF4 also promoting the secretion of apolipoprotein B (APOB). Despite a small increase in liver mass and lipid content, histologic evaluation revealed no evidence of steatohepatitis or fibrosis in Surf4fl/fl Alb-Cre+ mice. Acute depletion of hepatic SURF4 by CRISPR/Cas9 or liver-targeted siRNA in adult mice confirms these findings. Together, these data support the physiologic significance of SURF4 in the hepatic secretion of PCSK9 and APOB-containing lipoproteins and its potential as a therapeutic target in atherosclerotic cardiovascular diseases.

The relationship between pulse pressure with plasma PCSK9 and interleukin-6 among patients with acute ischemic stroke and dyslipidemia

Background and purposeA high plasma concentration of proprotein convertase subtilisin/kexin type 9 is characteristic of a prothrombotic state in cardiovascular diseases. Elevated inflammatory markers, such as interleukin-6, are associated with worse outcomes after ischemic stroke. We aimed to study the role of plasma PCSK9 and IL-6 in acute ischemic stroke with dyslipidemia. MethodsWe divided 123 enrolled patients with first-ever acute ischemic stroke into normotensive and high blood pressure groups and further into high and low pulse pressure subgroups. Clinical characteristics and inflammatory and metabolic parameters, including plasma PCSK9 and IL-6, were recorded. ResultsAfter the analysis of the normotensive and BP groups, there were positive correlations between PP and carotid stenosis (P = 0.031) and plaque numbers (P = 0.013) and between National Institute of Health Stroke Scale scores (P = 0.019) and carotid stenosis severity (P = 0.021) and resistance index (P = 0.04). There was a significant association between plasma cholesterol and PCSK9 (P = 0.044) in the low PP subgroup and IL-6 (P = 0.042) in the high PP subgroup. ConclusionsOur findings indicated that plasma PCSK9 levels were associated with the low PP subgroup, while IL-6 was associated with the high PP subgroup. Dyslipidemia control is also necessary for those who had a stroke and who have high PP. Further investigation to assess the role of PCSK9 and IL-6 in patients with stroke is required for early treatment and secondary prevention.

Low circulating PCSK9 levels in LPL homozygous children with chylomicronemia syndrome in a syrian refugee family in Lebanon.

Familial chylomicronemia syndrome is a rare autosomal recessive disorder of lipoprotein metabolism characterized by the presence of chylomicrons in fasting plasma and an important increase in plasma triglycerides (TG) levels that can exceed 22.58 mmol/l. The disease is associated with recurrent episodes of abdominal pain and pancreatitis, eruptive cutaneous xanthomatosis, lipemia retinalis, and hepatosplenomegaly. A consanguineous Syrian family who migrated to Lebanon was referred to our laboratory after perceiving familial chylomicronemia syndrome in two children. The LPL and PCSK9 genes were sequenced and plasma PCSK9 levels were measured. Sanger sequencing of the LPL gene revealed the presence of the p.(Val227Phe) pathogenic variant in exon 5 at the homozygous state in the two affected children, and at the heterozygous state in the other recruited family members. Interestingly, PCSK9 levels in homozygous carriers of the p.(Val227Phe) were ≈50% lower than those in heterozygous carriers of the variant (p-value = 0.13) and ranged between the 5th and the 7.5th percentile of PCSK9 levels in a sample of Lebanese children of approximately the same age group. Moreover, this is the first reported case of individuals carrying simultaneously an LPL pathogenic variant and PCSK9 variants, the L10 and L11 leucine insertion, which can lower and raise low-density lipoprotein cholesterol (LDL-C) levels respectively. TG levels fluctuated concomitantly between the two children, were especially high following the migration from a country to another, and were reduced under a low-fat diet. This case is crucial to raise public awareness on the risks of consanguineous marriages to decrease the emergence of inherited autosomal recessive diseases. It also highlights the importance of the early diagnosis and management of these diseases to prevent serious complications, such as recurrent pancreatitis in the case of familial hyperchylomicronemia.

Deciphering the molecular mechanisms underlying the increase in PCSK9 plasma levels in response to anti-PCSK9 mabs: In vitro study in human hepatoma-derived Huh7 cells

Background and Aims : In response to anti-PCSK9 monoclonal antibodies (mAbs) the circulating levels of total PCSK9 raised by approximately 4/7-fold (Shapiro et al. 2018). We aim to study the molecular mechanisms underlying this phenomenon.

LDL oxydées et récepteur des LDL oxydées associés à la proprotéine-convertase-subtilisine/kexine type 9 chez des patients avec diabète de type 2

AbstractProprotein Convertase Subtilisin/Kexin type 9 (PCSK9) plays a key role in the regulation of lipid metabolism, in inflammatory response and in the development of atherosclerosis. We evaluated plasma PCSK9 levels in Tunisian patients with type 2 diabetes mellitus (T2DM) and investigated its association with oxidized-LDL (Ox-LDL) and Lectin-Like Oxidized LDL Receptor-1 (LOX-1 ). Plasma PCSK9, Ox- LDL and LOX-1 levels were measured in a Tunisian cohort of patients with T2DM (n = 50) compared to an age- and gender-matched control group (n = 50). Plasma levels of PCSK9, Ox-LDL and LOX-1 were significantly higher in T2DM patients compared to controls (p < 0.0001). Univariate regression analysis showed that the plasma level of PCSK9 was positively associated to Ox-LDL and LOX-1 levels in diabetic patients (p = 0.004 ; p = 0.012; respectively); however, no-independent association was found after multiple linear regression analysis between those parameters. Our data showed that PCSK9 was positively associated to Ox-LDL and LOX-1 showing as specific regulation between the oxidative parameters and an enzyme regulating lipid metabolism. These results attest the impact of PCSK9 to develop atherosclerosis in T2DM in a Tunisian cohort. Finally, PCSK-9 could be a new marker of the development of atherosclerosis in diabetic patients.