The Association of Proprotein Convertase Subtilisin/Kexin Type 9 to Plasma Low-Density Lipoproteins: An Evaluation of Different Methods

Background: Proprotein convertase subtilisin/kexin type-9 (PCSK9) is key regulator of low-density lipoprotein (LDL) metabolism. A significant proportion of PCSK9 is believed to be associated with LDL in plasma as it circulates, although this finding is still a matter of debate. The purpose of this study was to establish an experimental method to investigate the presence of such an interaction in the bloodstream. Methods: We compared a number of well-established methods for lipoprotein (LP) isolation to clarify whether PCSK9 associates differently to circulating lipoproteins, such as KBr gradient ultracentrifugation, physical precipitation of ApoB-LPs, fast protein liquid chromatography (FPLC) and iodixanol gradient ultracentrifugation. Results: Our data show heterogeneity in PCSK9 association to lipoproteins according to the method used. Two methods, iodixanol ultracentrifugation and column chromatography, which did not involve precipitation or high salt concentration, consistently showed an interaction of PCSK9 with a subfraction of LDL that appeared to be more buoyant and have a lower size than average LDL. The percent of PCSK9 association ranged from 2 to 30% and did not appear to correlate to plasma or LDL cholesterol levels. Conclusions: The association of PCSK9 to LDL appeared to be sensitive to high salt concentrations. FPLC and iodixanol gradient ultracentrifugation appeared to be the most suitable methods for the study of this association.

Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors Induced Neurocognitive Disorder: A Pharmacovigilance Study by Analyzing the Data from the U.S. FDA Adverse Event Reporting System

PurposeThe neurocognitive disorder is a rare adverse event associated with Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) inhibitors in the randomized controlled trail (RCTs), there was limited evidence to prove their relation. This study aimed to assessing their association by detecting adverse signal in the FDA Adverse Event Reporting System (FAERS).MethodsThe disproportionality analysis was conducted to detect the potential adverse signal between neurocognitive disorders and PCSK9 inhibitors. The adverse event reports from the first quarter of 2004 to the second quarter of 2020 were extracted from the FAERS database.ResultsThere were 81,272 adverse reports correlated with the usage of the PCSK9 inhibitors, of which 152 reports corresponded with our inclusion criteria. Among them, there were 106 and 46 neurocognitive disorder reports related to the usage of Evolocumab and Alirocumab, respectively. The total ROR value presented negative disproportionality, however, Alirocumab has generated a positive signal with a higher ROR value in comparison with Evolocumab. Moreover, there were 61.19% of adverse reports were submitted by healthcare professionals. As for the outcome events, 7.79% of patients had initial or prolonged hospitalization and 3.90% suffered a disability.ConclusionThe pharmacovigilance research helps to find out more about PCSK9 inhibitor-related neurocognitive disorders. Although the positive signal was identified in Alirocumab in this study, it still required further research to prove the association between neurocognitive disorder and PCSK9 inhibitors. In addition, the tenable mechanism should be explored, which can improve the insight of this neotype lipid-lowering medicine.

Variations in TM6SF2, PCSK9 and PCSK7 genes and risk of hepatic steatosis after liver transplantation: a cross-sectional study

Background Genetic abnormalities might have important role in pathogenesis of hepatic steatosis after liver transplantation. We aimed to investigate association between genetic variations in transmembrane 6 superfamily member 2 (TM6SF2) rs58542926, proprotein convertase subtilisin/kexin type 9 (PCSK9) rs505151 and proprotein convertase subtilisin/kexin type 7 (PCSK7) rs2277287 with hepatic steatosis in liver transplant recipients. Methods In a cross-sectional study, adult (> 18 years) liver transplant recipients who were referred for their routine post-transplant follow-up between June 2018 and September 2018 were included in the study. Hepatic steatosis in transplant recipients was assessed by controlled attenuation parameter (CAP). Polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) was used to study TM6SF2 rs58542926, PCSK7 rs2277287 and PCSK9 rs505151 genotypes. Results 107 liver transplant recipients were included. There was no association between different genotypes of PCSK9 rs505151 and PCSK7 rs2277287 with hepatic steatosis in liver transplant recipients (P value > 0.05). The presence of TT genotype of TM6SF2 rs58542926 was higher in patients with hepatic steatosis measured by CAP after liver transplantation. In patients with moderate and severe hepatic steatosis (grade 2 and 3 steatosis), AG + GG genotypes of PCSK9 rs505151 were more prevalent than AA genotype (OR 8.667; 95% CI 1.841–40.879; P value = 0.004) compared to patients with mild steatosis (grade 1). In multivariate regression model, AG + GG genotypes of PCSK9 rs505151 were associated with moderate and severe steatosis in liver transplant recipients (OR 5.747; 95% CI 1.086–30.303; P value = 0.040). Conclusions Genetic variations in TM6SF2 rs58542926 and PCSK9 rs505151 might be associated with hepatic steatosis in liver transplant recipients.

Association Between Circulating Proprotein Convertase Subtilisin/Kexin Type 9 Concentrations and Cardiovascular Events in Cardiovascular Disease: A Systemic Review and Meta-Analysis

Background: A large amount of evidence suggests that proprotein convertase subtilisin/Kexin type 9 (PCSK9) inhibitors have clinical benefits in patients with cardiovascular disease (CVD). However, whether PCSK9 concentrations predict future cardiovascular (CV) events remains unclear.Methods: We conducted a meta-analysis to investigate the ability of PCSK9 concentrations to predict future CV events in patients with established CVD. A comprehensive search of electronic databases was conducted in June 2021. We included relative risk (RR) estimates with 95% CI or events of interest.Results: Eleven cohort studies including 8,471 patients with CVD were enrolled. The pooled RR of CV events for the increase in the circulating baseline PCSK9 concentrations by 1 SD showed a positive association in a random-effect model (RR 1.226, 95% CI: 1.055–1.423, P = 0.008). Similarly, the risk of the total CV events increased by 52% in the patients in the highest tertile compared with those in the lowest tertile of circulating PCSK9 concentrations (RR 1.523, 95% CI: 1.098–2.112, P = 0.012). The association between PCSK9 and CV events was stronger in stable patients with CVD, patients treated with statins, and Asian patients.Conclusions: High PCSK9 concentrations are significantly related to the increased risk of future CV events. These results enrich the knowledge of PCSK9 function and suggest the further possible clinical role of PCSK9 inhibitors.

PCSK9 (Proprotein Convertase Subtilisin/Kexin Type 9) Triggers Vascular Smooth Muscle Cell Senescence and Apoptosis: Implication of Its Direct Role in Degenerative Vascular Disease

Objective: PCSK9 (proprotein convertase subtilisin/kexin type 9) plays a critical role in cholesterol metabolism via the PCSK9–LDLR (low-density lipoprotein receptor) axis in the liver; however, evidence indicates that PCSK9 directly contributes to the pathogenesis of various diseases through mechanisms independent of its LDL-cholesterol regulation. The objective of this was to determine how PCSK9 directly acts on vascular smooth muscle cells (SMCs), contributing to degenerative vascular disease. Approach and Results: We first examined the effects of PCSK9 on cultured human aortic SMCs. Overexpression of PCSK9 downregulated the expression of ApoER2 (apolipoprotein E receptor 2), a known target of PCSK9. Treatment with soluble recombinant human ApoER2 or the DNA synthesis inhibitor, hydroxyurea, inhibited PCSK9-induced polyploidization and other cellular responses of human SMCs. Treatment with antibodies against ApoER2 resulted in similar effects to those observed with PCSK9 overexpression. Inducible, SMC-specific knockout of Pcsk9 accelerated neointima formation in mouse carotid arteries and reduced age-related arterial stiffness. PCSK9 was expressed in SMCs of human atherosclerotic lesions and abundant in the “shoulder” regions of vulnerable atherosclerotic plaques. PCSK9 was also expressed in SMCs of abdominal aortic aneurysm, which was inversely related to the expression of smooth muscle α-actin. Conclusions: Our findings demonstrate that PCSK9 inhibits proliferation and induces polyploidization, senescence, and apoptosis, which may be relevant to various degenerative vascular diseases.

Association of circulating proprotein convertase subtilisin/kexin type 9 concentration, prothrombin time and cardiovascular outcomes: a prospective cohort study

Background Proprotein convertase subtilisin/kexin type 9 (PCSK9) is considered to have multiple roles in the development of atherosclerosis, which is recently reported to participate in the thrombotic process. We aimed to examine the relationship between PCSK9 concentration, coagulation indexes and cardiovascular events. Methods A total of 2293 consecutive patients with angina-like chest pain and without lipid-lowering drugs treatment were enrolled and followed up for major adverse cardiovascular events (MACEs). Circulating PCSK9 concentration was determined by ELISA. The routine coagulation tests including activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time were performed. The associations between PCSK9 concentration, routine coagulation indicators and MACEs were analyzed. Results Patients with high PCSK9 levels had lower PT and APTT levels (all p < 0.05). However, PCSK9 concentration was only independently and negatively correlated with PT (β = − 0.115, p < 0.001). During a mean of 38.3 months, 186 (8.1%) MACEs were occurred. Multiple Cox regression analysis indicated high PCSK9 or low PT levels as risk factors related to MACEs. When the prognosis was analyzed by the combination of PCSK9 and PT levels, patients with high PCSK9 and low PT had higher incidence of MACEs compared to those with low PCSK9 and high PT. Conclusions Our study firstly suggested that PCSK9 concentration was negatively correlated with plasma levels of PT. Furthermore, high PCSK9 and low PT were associated with MACEs and the combination of PCSK9 with PT had an addictive effect on predicting cardiovascular outcomes in patients with chest pain, which was useful for further subdivision of cardiovascular risks.