Risk prediction with proprotein convertase subtilisin/kexin type 9 (PCSK9) in patients with stable coronary disease on statin treatment

Proprotein convertase subtilisin/kexin type 9: a promising marker of cardiovascular risk in post-menopausal diabetic women in primary prevention

Background and aims

Proprotein convertase subtilisin/kexin type 9 (PCSK9) increases circulating LDL levels and cardiovascular disease (CVD) risk; its levels may be related to the dysregulation of glycemic control and may be affected by estrogens. The aim of this study was to assess factors related to PCSK9 levels, and to evaluate the correlation between PCSK9 levels and CV parameters in post-menopausal diabetic women in primary prevention.

Methods

Generalized linear models (GLM) were adopted to evaluate predictors of PCSK9 levels as well as factors related to CV outcomes, such as pulse wave velocity (PWV), pulse pressure (PP), and augmentation index (AI).

Results

A total of 135 post-menopausal diabetic women, with a median (Q1-Q3) serum PCSK9 levels of 370.3 (344.0-409.4) ng/ml were enrolled. Apolipoprotein B values resulted an independent predictor of PCSK9 levels (B = 1.023; p < 0.001). However, LDL values were inversely related to PCSK9 levels (B = -0.578; p < 0.001). PCSK9 levels influenced PWV (B = 0.010; p = 0.010), but did not influence other CV outcomes.

Conclusion

ApoB and LDL may influence PCSK9 levels and PCSK9 directly influence PWV in post-menopausal diabetic women in primary prevention. Therefore, the relationship between PCSK9 and primary prevention cannot be excluded, thus highlighting its role as biomarker of CV risk.

Serum mature and furin-cleaved proprotein convertase subtilisin/kexin type 9 levels and their association with cardiovascular events in statin-treated patients with cardiovascular disease

BACKGROUND AND AIMS

Previous studies have not found a consistent association between circulating proprotein convertase subtilisin/kexin type 9 (PCSK9) levels and the risk of cardiovascular events partly due to measurement methods that cannot distinguish between uncleaved and furin-cleaved forms of PCSK9.

METHODS

This is a prespecified sub-study of the REAL-CAD study which is a prospective, multicenter, randomized trial to compare high- versus low-dose statin in patients with stable coronary artery disease (CAD). The primary endpoint was major adverse cerebrovascular and cardiovascular events (MACCE) defined as a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal ischemic stroke, or unstable angina requiring emergency hospitalization. In this case-cohort study, serum mature (uncleaved) and furin-cleaved PCSK9 levels obtained at 6 months after randomization were measured among 426 participants who developed MACCE (cases) and 1,478 randomly selected participants (sub-cohort).

RESULTS

From 1,478 patients in the sub-cohort, the Cox proportional hazards models with a pseudolikelihood method for case-cohort design revealed that the risk of the primary endpoint in patients with the highest quartile of mature PCSK9 levels was similar to that in the lowest quartile (hazard ratio [HR] 0.809; 95% confidence intervals [CI], 0.541-1.209). Similarly, the HR for the highest to lowest quartiles of furin-cleaved PCSK9 was 0.948 (95% CI, 0.645-1.392) (P = 0.784). Compared to the lowest quartile, neither serum mature nor furin-cleaved PCSK9 levels predicted MACCE.

CONCLUSIONS

In a large-scale secondary prevention cohort, serum mature and furin-cleaved PCSK9 levels did not provide useful information for predicting future cardiovascular events in statin-treated patients with stable CAD.

The Anti-Thrombotic Effects of PCSK9 Inhibitors

Atherosclerosis is the primary process that underlies cardiovascular disease. The connection between LDL cholesterol and the formation of atherosclerotic plaques is established by solid evidence. PCSK9 inhibitors have proven to be a valuable and practical resource for lowering the LDL cholesterol of many patients in recent years. Their inhibitory effect on atherosclerosis progression seems to be driven not just by lipid metabolism modification but also by LDL-independent mechanisms. We review the effect of PCSK9 inhibitors on various mechanisms involving platelet activation, inflammation, endothelial dysfunction, and the resultant clot formation. The main effectors of PCSK9 activation of platelets are CD36 receptors, lipoprotein(a), oxidised LDL particles, tissue factor, and factor VIII. Many more molecules are under investigation, and this area of research is growing rapidly.

The Concentration of PCSK9-Lp(a) Complexes and the Level of Blood Monocytes in Males with Coronary Atherosclerosis

In this study we analyzed the concentration of lipoprotein(a) (Lp(a)), PCSK9-Lp(a) complexes and the circulating monocyte subsets in coronary atherosclerosis. For this study, 257 patients with coronary atherosclerosis and 68 patients without stenotic atherosclerosis in the coronary, carotid and lower extremity arteries (control group) were enrolled. The monocyte subpopulations (classical CD14++CD16-, intermediate CD14++CD16+ and non-classical CD14+CD16++) were analyzed by direct immunofluorescence and flow cytometry. The Lp(a) and PCSK9-Lp(a) complexes in the serum were detected by ELISA. The concentration of Lp(a) was higher in the coronary atherosclerosis group compared with the controls (23.0 (9.1; 73.3) mg/dL versus 10.7 (4.7; 25.0) mg/dL, p < 0.05). No correlations between the level of Lp(a) and the concentration of the PCSK9-Lp(a) complexes, nor between the level of Lp(a) or PCSK9 and the total number of monocytes, were observed in either group. A slight positive correlation between the concentration of PCSK9-Lp(a) complexes and the absolute level of monocytes was obtained (r = 0.20, p = 0.002) in the patients with atherosclerosis due to the intermediate monocyte subsets (r = 0.33, p = 0.04). According to regression analysis, both the PCSK9-Lp(a) complexes concentration and BMI were related to the absolute number of blood monocytes in patients with atherosclerosis. Further studies are required to determine the pathogenetic contribution of PCSK9-Lp(a) complexes to the development of atherosclerosis.

Computational Design, Synthesis, and Biological Evaluation of Diimidazole Analogues Endowed with Dual PCSK9/HMG-CoAR-Inhibiting Activity

Proprotein convertase subtilisin/kexin 9 (PCSK9) is responsible for the degradation of the hepatic low-density lipoprotein receptor (LDLR), which regulates circulating cholesterol levels. Consequently, the PCSK9 inhibition is a valuable therapeutic approach for the treatment of hypercholesterolemia and cardiovascular diseases. In our studies, we discovered Rim13, a polyimidazole derivative reducing the protein-protein interaction between PCSK9 and LDLR with an IC₅₀ of 1.6 μM. The computational design led to the optimization of the shape of the PCSK9/ligand complementarity, enabling the discovery of potent diimidazole derivatives. In fact, carrying out biological assays to fully characterize the cholesterol-lowering activity of the new analogues and using both biochemical and cellular techniques, compound Dim16 displayed improved PCSK9 inhibitory activity (IC₅₀ 0.9 nM). Interestingly, similar to other lupin-derived peptides and their synthetic analogues, some compounds in this series showed dual hypocholesterolemic activity since some of them complementarily inhibited the 3-hydroxy-3-methylglutaryl coenzyme A reductase.

Association of high proprotein convertase subtilisin/kexin type 9 antibody level with poor prognosis in patients with diabetes: a prospective study

In addition to pathogenic autoantibodies, polyclonal autoantibodies with unknown physiological roles and pathogenicity are produced in the body. Moreover, serum antibodies against the proprotein convertase subtilisin/kexin type 9 (PCSK9) protein, which is integral to cholesterol metabolism, have also been observed. PCSK9 was also reported to be associated with insulin secretion and diabetes mellitus (DM). Therefore, we aimed to examine the clinical significance of PCSK9 antibodies (PCSK9-Abs) levels. We measured blood PCSK9-Abs and PCSK9 protein levels in 109 healthy donors (HDs) and 274 patients with DM (type 2 DM: 89.8%) using an amplified luminescence proximity homogeneous assay-linked immunosorbent assay. Subsequently, patients with DM were followed up (mean: 4.93 years, standard deviation: 2.77 years, maximum: 9.58 years, minimum: 0.07 years) to examine associations between antibody titers and mortality, myocardial infarction, stroke onset, and cancer. The primary endpoint of this study was to examine whether PCSK9-Abs can be a prognostic marker for overall mortality among the patients with diabetes. The secondary endpoint was to examine the relationship between PCSK9-Abs and clinical parameters. Although both PCSK9-Abs and PCSK9 protein levels were significantly higher in the DM group than in the HD group (p < 0.008), PCSK9-Abs and PCSK9 protein levels showed no correlation in either group. Mortality was significantly associated with higher PCSK9-Ab levels, but unrelated to PCSK9 protein levels. After investigating for potential confounding factors, higher PCSK9-Ab levels were still associated with increased mortality among the patients with DM. PCSK9-Abs may be a novel prognostic marker for overall mortality in patients with diabetes, and further studies are warranted to verify its usefulness.

Drug-Drug Interaction between Antiplatelet Therapy and Lipid-Lowering Agents (Statins and PCSK9 Inhibitors)

Lipid-lowering agents and antiplatelet drugs are guideline-recommended standard treatment for secondary prevention of acute thrombotic events in patients with increased cardiovascular risk. Aspirin is the most frequently used antiplatelet drug, either alone or in combination with other antiplatelet agents (P2Y₁₂ inhibitors), while statins are first-line treatment of hypercholesterolemia. The well-established mode of action of aspirin is inhibition of platelet-dependent thromboxane formation. In addition, aspirin also improves endothelial oxygen defense via enhanced NO formation and inhibits thrombin formation. Low-dose aspirin exerts in addition anti-inflammatory effects, mainly via inhibition of platelet-initiated activation of white cells.Statins inhibit platelet function via reduction of circulating low-density lipoprotein-cholesterol (LDL-C) levels and a more direct inhibition of platelet function. This comprises inhibition of thromboxane formation via inhibition of platelet phospholipase A₂ and inhibition of (ox)LDL-C-mediated increases in platelet reactivity via the (ox)LDL-C receptor (CD36). Furthermore, statins upregulate endothelial NO-synthase and improve endothelial oxygen defense by inhibition of NADPH-oxidase. PCSK9 antibodies target a serine protease (PCSK9), which promotes the degradation of the LDL-C receptor impacting on LDL-C plasma levels and (ox)LDL-C-receptor-mediated signaling in platelets similar to but more potent than statins.These functionally synergistic actions are the basis for numerous interactions between antiplatelet and these lipid-lowering drugs, which may, in summary, reduce the incidence of atherothrombotic vascular events.

PSMA2 knockdown impacts expression of proteins involved in immune and cellular stress responses in human lung cells

Proteasome subunit alpha type-2 (PSMA2) is a critical component of the 20S proteasome, which is the core particle of the 26S proteasome complex and is involved in cellular protein quality control by recognizing and recycling defective proteins. PSMA2 expression dysregulation has been detected in different human diseases and viral infections. No study yet has reported PSMA2 knockdown (KD) effects on the cellular proteome.

METHODS

We used SOMAScan, an aptamer-based multiplexed technique, to measure >1300 human proteins to determine the impact of PSMA2 KD on A549 human lung epithelial cells.

RESULTS

PSMA2 KD resulted in significant dysregulation of 52 cellular proteins involved in different bio-functions, including cellular movement and development, cell death and survival, and cancer. The immune system and signal transduction were the most affected cellular functions. PSMA2 KD caused dysregulation of several signaling pathways involved in immune response, cytokine signaling, organismal growth and development, cellular stress and injury (including autophagy and unfolded protein response), and cancer responses.

CONCLUSIONS

In summary, this study helps us better understand the importance of PSMA2 in different cellular functions, signaling pathways, and human diseases.

Landscape of lipidomics in cardiovascular medicine from 2012 to 2021: A systematic bibliometric analysis and literature review

Lipidomics has shaped our knowledge of how lipids play a central role in cardiovascular diseases (CVD), whereas there is a lack of a summary of existing research findings. This study performed a bibliometric analysis of lipidomics research in cardiovascular medicine to reveal the core countries, institutions, key researchers, important references, major journals, research hotspots and frontiers in this field. From 2012 to 2021, a total of 761 articles were obtained from the Web of Science Core Collection database. There is a steady increase of publications yearly. The United States and China are on the top of the list regarding article output. The institutions with the most publications were the Baker Heart and Diabetes Institute, the Chinese Academy of Sciences and Harvard Medical School. Peter J Meikle was both the most published and most co-cited author. The major journal in this field is Journal of lipid research. Keyword co-occurrence analysis indicated that coronary heart disease, mass spectrometry, risk, fatty acid, and insulin resistance have become hot topics in this field and keyword burst detection suggests that metabolomics, activation, liver, low density lipoprotein are the frontiers of research in recent years. Collectively, lipidomics in CVD is still in its infancy with a steady increase yearly. More in-depth studies in this area are warranted in the future.

Sex difference in circulating PCSK9 and its clinical implications

Proprotein convertase subtilisin kexin type 9 (PCSK9) is a proprotein convertase that increases plasma low-density lipoprotein cholesterol (LDL-C) levels by triggering the degradation of LDL receptors (LDLRs). Beyond the regulation of circulating LDL-C, PCSK9 also has direct atherosclerotic effects on the vascular wall and is associated with coronary plaque inflammation. Interestingly, emerging data show that women have higher circulating PCSK9 concentrations than men, suggesting that the potential roles of PCSK9 may have different impacts according to sex. In this review, we summarize the studies concerning sex difference in circulating levels of PCSK9. In addition, we report on the sex differences in the relations of elevated circulating PCSK9 levels to the severity and prognosis of coronary artery disease, the incidence of type 2 diabetes mellitus, and neurological damage after cardiac arrest and liver injury, as well as inflammatory biomarkers and high-density lipoprotein cholesterol (HDL-C). Moreover, sex difference in the clinical efficacy of PCSK9 inhibitors application are reviewed. Finally, the underlying mechanisms of sex difference in circulating PCSK9 concentrations and the clinical implications are also discussed.

Association of PCSK9 with inflammation and platelet activation markers and recurrent cardiovascular risks in STEMI patients undergoing primary PCI with or without diabetes

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been shown to be predictive of cardiovascular outcomes in stable coronary artery disease with diabetes. We aimed to assess the relationship between PCSK9 and major adverse cardiovascular events (MACEs) in ST-segment elevation myocardial infarction (STEMI) patients with or without diabetes, as well as the relationships between PCSK9 and metabolism, inflammation and platelet activation markers.

METHODS

A total of 1027 patients with STEMI undergoing primary percutaneous coronary intervention (PCI) and without prior lipid-lowering therapy were consecutively enrolled and the baseline plasma PCSK9 levels were determined by ELISA. Patients were divided into high and low PCSK9 groups according to PCSK9 median. All patients were followed up for the occurrence of MACEs. The associations of PCSK9 with metabolism, inflammation and platelet activation markers and MACEs were evaluated.

RESULTS

PCSK9 levels were positively correlated with triglycerides, high-sensitivity C reactive protein, soluble CD40 ligand and soluble P-selectin levels, and the correlations were stronger in diabetic patients than in non-diabetic patients. In diabetic patients receiving ticagrelor, PCSK9 levels were positively correlated with maximal platelet aggregation measured by light transmittance aggregometry and maximum amplitude of adenosine diphosphate-induced platelet-fibrin clots measured by thrombelastography in the maintenance phase of treatment, whereas no correlations were found in non-diabetic patients. During a median follow-up of 2.0 years, 155 (15.1%) MACEs occurred. The Kaplan-Meier analysis displayed that the patients with high PCSK9 levels had lower event-free survival rate than those with low PCSK9 levels (P = 0.030). When participants were categorized into 4 subgroups according to PCSK9 levels and diabetes status, high PCSK9 levels plus diabetes subgroup had the lowest cumulative event-free survival rate (P = 0.043). Multivariable Cox regression analysis revealed that high PCSK9 levels were independently associated with MACEs in diabetic patients (hazard ratio 2.283, 95% confidence interval: 1.094-4.764, P = 0.028), but not in the whole cohort or non-diabetic patients.

CONCLUSIONS

The study showed that high PCSK9 levels were independently associated with MACEs in STEMI patients with diabetes undergoing primary PCI, and the association may be due to stronger correlations of PCSK9 with inflammation and platelet activation markers in diabetic patients.

Dammarane-type saponins with proprotein convertase subtilisin/kexin type 9 inhibitory activity from Gynostemma pentaphyllum

Seven undescribed dammarane-type saponins, gypenosides LXXXI-LXXXVII, together with four known compounds, were isolated from the whole herb of Gynostemma pentaphyllum. The chemical structures of these undescribed compounds were elucidated on the basis of physical and spectroscopic analysis and comparison with literature data. All the isolates were evaluated for their proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitory activities in HepG2 cells. Among them, gypenosides LXXXII-LXXXVII, gynosaponin II, IV and VI suppressed the expression of PCSK9 in LPDS-induced HepG2 cells at 20 μM; gypenosides LXXXII, LXXXV and LXXXVII showed inhibitory activities against PCSK9 at 10 μM; notably, gypenoside LXXXII still exhibited inhibitory activity against PCSK9 at 5 μM.

Associations of pro-protein convertase subtilisin-like kexin type 9, soluble low-density lipoprotein receptor and coronary artery disease: A case-control study

BACKGROUND

Low-density lipoprotein receptor (LDLR) is the primary pathway for removal of cholesterol from the circulation, pro-protein convertase subtilisin-like kexin type 9 (PCSK9) is a secreted protease that binds to and promotes degradation of the LDLR protein. The goal of this case-control study was to investigate the role of soluble LDLR (sLDLR) and PCSK9 in coronary artery disease (CAD) and investigate the relationship between these two indices and CAD.

METHODS

In a sample of 144 Chinese patients recruited between January 2018 and August 2018, 81 cases with mild and severe stenosis characterized by coronary angiograph (CAG) and 63 healthy controls were selected using the propensity score matching (PSM) based on demographics and medical history. sLDLR and PCSK9 concentrations were determined using enzyme-linked immunosorbent assay (ELISA), Immuno-precipitation (IP) and western blotting. Multivariable logistic models were used to assess the associations between the degree of coronary artery stenosis and the biomarkers of interest.

RESULTS

Higher PCSK9 was found to be a significant predictor of coronary artery stenosis when comparing cases who had severe stenosis vs. controls (OR = 1.016, 95%CI: 1.009-1.024), and cases who had mild stenosis vs. controls (OR = 1.009, 95%CI: 1.003-1.015). sLDLR was positively corrected with PCSK9, which confounded the association between CAD and PCSK9. Compared to patients with mild-stenosis, patients with severe-stenosis also showed a higher level of PCSK9 (OR = 1.005, 95%CI: 1.007-1.013).

CONCLUSIONS

These findings suggest that elevated PSCK9 may contribute to the odds of developing CAD, with a higher degree of coronary artery stenosis.

NAFLD fibrosis score is correlated with PCSK9 and improves outcome prediction of PCSK9 in patients with chest pain: a cohort study

BACKGROUND

The risk of liver fibrosis in non-alcoholic fatty liver disease (NAFLD) can be easily evaluated by noninvasive scoring systems, of which the NAFLD fibrosis score (NFS) is the most commonly used. Proprotein convertase subtilisin/kexin type 9 (PCSK9), a new predictor of cardiovascular events, has been reported to be associated with cardiovascular outcomes and NAFLD. However, the relationship of NFS with PCSK9 and their prognostic abilities in cardiovascular risks are unknown.

METHODS

A total of 2008 hospitalized subjects who had chest pain without lipid-lowering therapy were consecutively included. Baseline clinical data were collected, and the NFS was calculated. The circulating PCSK9 concentration was determined by enzyme immunoassay. The major adverse cardiovascular event (MACE) occurrences were recorded in the follow-up period. Associations of PCSK9 concentration with NFS were examined. All of the participants were categorized into three groups according to NFS levels and were further stratified by PCSK9 tertiles to evaluate the MACEs.

RESULTS

158 (7.87%) MACEs were observed during a mean of 3.2 years of follow-up. NFS levels were independently related to higher PCSK9 levels according to multivariable linear regression analysis. Furthermore, elevated PCSK9 and NFS concentrations were respectively associated with increased MACE incidence in multivariable Cox regression models. When combining NFS status with PCSK9 tertiles as a stratifying factor, patients with intermediate-high NFS and high PCSK9 levels had higher risks of events than those with low NFS and low PCSK9 levels.

CONCLUSIONS

This study revealed for the first time that NFS is positively related to PCSK9 and that the combination of NFS and PCSK9 greatly increased the risk of MACEs in patients with chest pain, providing a potential link between NFS and PCSK9 for predicting cardiovascular events.

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.

Circulating Biomarkers for Cardiovascular Disease Risk Prediction in Patients With Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of death globally. Risk assessment is crucial for identifying at-risk individuals who require immediate attention as well as to guide the intensity of medical therapy to reduce subsequent risk of CVD. In the past decade, many risk prediction models have been proposed to estimate the risk of developing CVD. However, in patients with a history of CVD, the current models that based on traditional risk factors provide limited power in predicting recurrent cardiovascular events. Several biomarkers from different pathophysiological pathways have been identified to predict cardiovascular events, and the incorporation of biomarkers into risk assessment may contribute to enhance risk stratification in secondary prevention. This review focuses on biomarkers related to cardiovascular and metabolic diseases, including B-type natriuretic peptide, high-sensitivity cardiac troponin I, adiponectin, adipocyte fatty acid-binding protein, heart-type fatty acid-binding protein, lipocalin-2, fibroblast growth factor 19 and 21, retinol-binding protein 4, plasminogen activator inhibitor-1, 25-hydroxyvitamin D, and proprotein convertase subtilisin/kexin type 9, and discusses the potential utility of these biomarkers in cardiovascular risk prediction among patients with CVD. Many of these biomarkers have shown promise in improving risk prediction of CVD. Further research is needed to assess the validity of biomarker and whether the strategy for incorporating biomarker into clinical practice may help to optimize decision-making and therapeutic management.

Platelet-Derived PCSK9 Is Associated with LDL Metabolism and Modulates Atherothrombotic Mechanisms in Coronary Artery Disease

Platelets play a significant role in atherothrombosis. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is critically involved in the regulation of LDL metabolism and interacts with platelet function. The effect of PCSK9 in platelet function is poorly understood. The authors of this article sought to characterize platelets as a major source of PCSK9 and PCSK9's role in atherothrombosis. In a large cohort of patients with coronary artery disease (CAD), platelet count, platelet reactivity, and platelet-derived PCSK9 release were analyzed. The role of platelet PCSK9 on platelet and monocyte function was investigated in vitro. Platelet count and hyper-reactivity correlated with plasma LDL in CAD. The circulating platelets express on their surface and release substantial amounts of PCSK9. Release of PCSK9 augmented platelet-dependent thrombosis, monocyte migration, and differentiation into macrophages/foam cells. Platelets and PCSK9 accumulated in tissue derived from atherosclerotic carotid arteries in areas of macrophages. PCSK9 inhibition reduced platelet activation and platelet-dependent thrombo-inflammation. The authors identified platelets as a source of PCSK9 in CAD, which may have an impact on LDL metabolism. Furthermore, platelet-derived PCSK9 contributes to atherothrombosis, and inhibition of PCSK9 attenuates thrombo-inflammation, which may contribute to the reported beneficial clinical effects.

Gypenoside LVI improves hepatic LDL uptake by decreasing PCSK9 and upregulating LDLR expression

BACKGROUNDS

Atherosclerotic Cardiovascular Disease (ASCVD) is defined as ischemic or endothelial dysfunction-various inflammatory diseases, which is mainly caused by excessive low-density lipoprotein cholesterol (LDL-C) in circulating blood. Gynostemma pentaphyllum is a traditional Chinese medicine, and total Gypenosides are used for the treatment of hyperlipidemia and to reduce circulating proprotein convertase subtilisin/kexin type 9 (PCSK9) level. However, which gypenoside involved in the modulation of PCSK9 expression is still unknown.

PURPOSE

This study aimed to discover effective PCSK9 inhibitors from Gypenosides in accordance with the 2019 ESC/EAS guidelines.

METHODS

HPLC was employed to determine major six components of Gypenosides. The inhibitory activity on secreted PCSK9 in HepG2 of six major compounds from Gypenosides were screened by ELISA. The level of low-density lipoprotein (LDL) receptor (LDLR) was determined by Flow cytometry and Immunofluorescence. The expression levels of PCSK9, LDLR and Sterol-regulatory element binding proteins-2 (SREBP-2) were analyzed by qPCR and Western blot. DiI-LDL was added to evaluated LDL uptake into HepG2.

RESULTS

The results suggested that the mRNA and protein levels of PCSK9 were down-regulated by Gypenoside LVI and the LDLR degradation in lysosomes system was inhibited, thereby leading to an increasing in LDL uptake into HepG2 cells. Furthermore, Gypenoside LVI decreased PCSK9 expression induced by stains. Altogether, Gypenoside LVI enhances LDL uptake into HepG2 cells by increased LDLR level on cell-surface and suppressed PCSK9 expression.

CONCLUSION

This indicates that Gypenoside LVI can be used as a useful supplement for statins in the treatment of hypercholesterolemia. This is firstly reported that monomeric compound of G. pentaphyllum planted in Hunan province has the effect of increasing LDL-C uptake in hepatocytes via inhibiting PCSK9 expression.

Relationship between Circulating PCSK9 and Markers of Subclinical Atherosclerosis-The IMPROVE Study

(1) Background and purpose: circulating proprotein convertase subtilisin/kexin type 9 (PCSK9) is one of the key regulators of cholesterol metabolism. Despite this, its role as a player in atherosclerosis development is still matter of debate. Here, we investigated the relationships between this protein and several markers of subclinical atherosclerosis. (2) Methods: the IMPROVE study enrolled 3703 European subjects (54–79 years; 48% men; with ≥3 vascular risk factors), asymptomatic for cardiovascular diseases. PCSK9 levels were measured by ELISA. B-mode ultrasound was used to measure markers of carotid subclinical atherosclerosis. (3) Results: in the crude analysis, PCSK9 levels were associated with several baseline measures of carotid intima-media thickness (cIMT) (all p < 0.0001); with cIMT change over time (Fastest-IMTmax-progr) (p = 0.01); with inter-adventitia common carotid artery diameter (ICCAD) (p < 0.0001); and with the echolucency (Grey Scale Median; GSM) of both carotid plaque and plaque-free common carotid IMT (both p < 0.0001). However, after adjustment for age, sex, latitude, and pharmacological treatment, all the afore-mentioned correlations were no longer statistically significant. The lack of correlation was also observed after stratification for sex, latitude, and pharmacological treatments. (4) Conclusions: in subjects who are asymptomatic for cardiovascular diseases, PCSK9 plasma levels do not correlate with vascular damage and/or subclinical atherosclerosis of extracranial carotid arteries.

The relationship between protein convertase subtilisin kexin type-9 levels and extent of coronary artery disease in patients with non-ST-elevation myocardial infarction

BACKGROUND

Cardiovascular disease is one of the leading causes of death worldwide. According to the results of various studies, protein convertase subtilisin kexin type-9 (PCSK9) was determined as a novel risk factor for stable coronary artery disease. Few studies have investigated the relationship between PCSK9 levels and the severity of coronary artery disease in patients with acute coronary syndrome; thus, we herein aimed to investigate this relationship in patients with non-ST-elevation myocardial infarction (NSTEMI) who underwent coronary angiography.

PATIENTS AND METHODS

Herein, 168 patients with NSTEMI were prospectively enrolled, and severity of atherosclerotic lesions was determined using SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery (SYNTAX), Gensini and Jeopardy scores. Plasma PCSK9 levels, lipid parameters and C-reactive protein levels were measured after a 12-h fasting period. The relationship of PCSK9 levels and clinical and laboratory parameters of patients with their SYNTAX, Gensini and Jeopardy scores was investigated.

RESULTS

Pearson correlation analysis showed a strong positive correlation between PCSK9 and the three scores (P < 0.001, r > 0.5 for all). In ROC analysis, a mid-high SYNTAX score of at least 25 was predicted with a sensitivity of 81% and a specificity of 63% when the PCSK9 level was higher than 52.8 ng/ml (area under a curve 0.76, P < 0.001). Multivariate linear regression analysis revealed that PCSK9, low-density lipoprotein cholesterol and creatinine levels were independent predictors of a high SYNTAX score.

CONCLUSION

Taken together, high PCSK9 levels may be a risk factor for adverse events in patients with NSTEMI. Aggressive lipid-lowering therapies may benefit this group of patients.

Effect of directly acting antivirals for hepatitis C virus infection on proprotein convertase subtilisin/kexin type 9 level

BACKGROUND AND AIMS

Eradication of the hepatitis C virus (HCV) may affect proprotein convertase subtilisin/kexin type 9 (PCSK9) levels and cardiovascular risk. However, information regarding PCSK9 level after HCV eradication is lacking. Hence, in this case-control retrospective study, we aimed to evaluate PCSK9 level from pretherapy baseline up to sustained virological response (SVR).

METHODS

Eighty-four patients treated with directly acting antivirals (DAAs) between July 2015 and May 2018 were enrolled. Differences in baseline PCSK9 level due to absence/presence of recorded baseline characteristics (covariates) were evaluated. Changes in PCSK9 levels from pretherapy to SVR (ΔPCSK9) and their correlations with the covariates were assessed. The repeated measures analysis of variance was used to investigate the differences in PCSK9 level from the baseline to the achievement of SVR due to absence/presence of any covariate.

RESULTS

The mean age of the patients was 67.6 ± 11 years, and 53.6% were males. Baseline PCSK9 levels were statistically lower in patients using statins than in those not using statins (mean, 70.3 ± 43.1 ng/mL vs 271.8 ± 252.2 ng/mL; P = .017). PCSK9 level decreased significantly from baseline to the time of SVR (255 ± 248 ng/mL vs 169 ± 188 ng/mL; P < .001). PCSK9 levels were statistically higher in the HCV-infected patients at baseline than in the control group (255 ± 248 vs 166.3 ± 120.2 ng/mL; P = .020); however, this difference was lost after achieving SVR (mean, 169 ± 188 vs 166.3 ± 120.2 ng/mL; P = .464). Changes in PCSK9 level was not statistically related to any of the recorded covariates. The PCSK9 mean level did not differ significantly with absence/presence of any covariate from pretherapy to SVR.

CONCLUSIONS

The reduction in mean PCSK9 level from baseline pretherapy to after HCV eradication was statistically significant. Whether PCSK9 is a new biomarker for cardiovascular risk in these patients remains to be ascertained.

Prognostic value of PCSK9 levels in patients with non-ST elevation myocardial infarction undergoing percutaneous coronary intervention (PCI)

BACKGROUND

The role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in predicting major adverse cardiovascular events (MACEs) in Non-ST elevation myocardial infarction (NSTEMI) patients is still an open question, and the PCSK9 concentration of clinical usefulness remains unknown in guiding treatment.

METHODS AND RESULTS

A total of 272 patients with NSTEMI were included in our prospective observational cohort study. Patients were followed up for 1 year. Their baseline plasma PCSK9 levels were determined by enzyme-linked immunosorbent assay. Patients were divided into high, medium, and low PCSK9 groups. All patients followed up for the occurrence of MACEs and received PCI therapy after admission. The associations of PCSK9 with MACEs were evaluated. The results showed that the incidence of composite MACEs was greater at higher concentrations of PCSK9. PCSK9 level was related to the level of lipoproteins, high-sensitivity C-reactive protein (hs-CRP), platelet volume distribution width, and D-Dimer. There was also a statistically significant correlation between PCSK9 concentrations and the GRACE score. The Kaplan-Meier curves showed that patients with high PCSK9 level had lower event-free survival rate. The survival analysis indicated high level of PCSK9-predicted MACEs independently. Subgroup analysis demonstrated that the prognostic value of high PCSK9 level was greater for patients classified by the GRACE score as high risk.

CONCLUSION

In an NSTEMI setting, the concentration of PCSK9 is associated with hypercoagulability and hyperinflammation. High levels of PCSK9 independently predict future MACEs in patients with NSTEMI, particularly those classified by the GRACE score as high risk.

Plasma proprotein convertase subtilisin/kexin type 9 concentration and recurrent cardiovascular events in patients with familial hypercholesterolemia

AIMS

Familial hypercholesterolemia patients are characterized by early onset of coronary artery calcification and atherosclerosis, and high incidence of cardiovascular events. Plasma proprotein convertase subtilisin/kexin type 9 was reported to be a predictor for cardiovascular risk in the general population. However, its prognostic value for predicting recurrent cardiovascular events in familial hypercholesterolemia patients remains undetermined.

METHODS

A total of 249 patients with molecularly and/or clinically (Dutch Lipid Clinic Network score > 6) defined familial hypercholesterolemia who had experienced a first cardiovascular event were consecutively included and plasma proprotein convertase subtilisin/kexin type 9 concentrations were measured by enzyme-linked immunosorbent assay. Coronary artery calcification was measured using Agatston method and coronary severity was assessed by Gensini score, respectively. All patients received standard lipid-lowering therapy and were followed-up for recurrent cardiovascular events. Univariate and multivariate regression and Cox analyses was used to calculate hazard ratios with 95% confidence interval.

RESULTS

Circulating proprotein convertase subtilisin/kexin type 9 concentrations were positively associated with coronary artery calcification scores and Gensini score by both univariate and multivariate analyses. During a mean follow-up of 43 ± 19 months, 29 (11.51%) recurrent cardiovascular events occurred. Kaplan-Meier analysis showed that patients with the highest proprotein convertase subtilisin/kexin type 9 levels had the lowest event-free survival time. Multivariable Cox regression analysis revealed that proprotein convertase subtilisin/kexin type 9 was independently associated with recurrent cardiovascular events (hazard ratio: 1.45, 95% confidence interval: 1.11-1.88). The combination of proprotein convertase subtilisin/kexin type 9 to Cox prediction model led to an enhanced predictive value for recurrent cardiovascular events.

CONCLUSIONS

Increased level of proprotein convertase subtilisin/kexin type 9 was a significant risk factor of atherosclerosis and independently predicted future recurrent cardiovascular events in familial hypercholesterolemia patients receiving standard lipid-lowering treatment.

Association Between Circulating Proprotein Convertase Subtilisin/Kexin Type 9 and Major Adverse Cardiovascular Events, Stroke, and All-Cause Mortality: Systemic Review and Meta-Analysis

Background: Proprotein convertase subtilisin/kexin type 9 (PCSK9), a pivotal protein in low-density lipoprotein cholesterol metabolism, has been validated to be an established target for cardiovascular (CV) risk reduction. Nevertheless, prospective studies concerning the associations between circulating PCSK9 and the risk of CV events and mortality have yielded, so far, inconsistent results. Herein, we conducted a meta-analysis to evaluate the association systemically. Methods: Pertinent studies were identified from PubMed, EMBASE, and Cochrane Library database through July 2020. Longitudinal studies investigating the value of circulating PCSK9 for predicting major adverse cardiovascular events (MACEs) or stroke or all-cause mortally with risk estimates and 95% confidence intervals (CI) were included in the analyses. Dose-response meta-analysis was also applied to evaluate circulating PCSK9 and risk of MACEs in this study. Results: A total of 22 eligible cohorts comprising 28,319 participants from 20 eligible articles were finally included in the study. The pooled relative risk (RR) of MACEs for one standard deviation increase in baseline PCSK9 was 1.120 (95% CI, 1.056-1.189). When categorizing subjects into tertiles, the pooled RR for the highest tertile of baseline PCSK9 was 1.252 (95% CI, 1.104-1.420) compared with the lowest category. This positive association between PCSK9 level and risk of MACEs persisted in sensitivity and most of the subgroup analyses. Twelve studies were included in dose-response meta-analysis, and a linear association between PCSK9 concentration and risk of MACEs was observed (x2 test for non-linearity = 0.31, P non-linearity = 0.575). No significant correlation was found either on stroke or all-cause mortality. Conclusion: This meta-analysis added further evidence that high circulating PCSK9 concentration significantly associated with increased risk of MACEs, and a linear dose-response association was observed. However, available data did not suggest significant association either on stroke or all-cause mortality. Additional well-designed studies are warranted to further investigate the correlations between PCSK9 concentration and stroke and mortality.

The Effect of Proprotein Convertase Subtilisin Kexin Type 9 Inhibitors on Circulating Endothelial Progenitor Cells in Patients with Cardiovascular Disease

PURPOSE

Circulating endothelial progenitor cells (cEPCs) are vital to vascular repair by re-endothelialization. We aimed to explore the effect of proprotein convertase subtilisin kexin type 9 inhibitors (PCSK9i) on cEPCs hypothesizing a possible pleiotropic effect.

METHODS

Patients with cardiovascular disease (CVD) were sampled for cEPCs at baseline and following the initiation of PCSK9i. cEPCs were assessed using flow cytometry by the expression of CD34⁽⁺⁾/CD133⁽⁺⁾ and vascular endothelial growth factor receptor (VEGFR)-2⁽⁺⁾, and by the formation of colony-forming units (CFUs) and production of VEGF.

RESULTS

Our cohort included 26 patients (median age 68 (IQR 63, 73) years; 69% male). Following 3 months of treatment with PCSK9i and a decline in low-density lipoprotein cholesterol levels (153 (IQR 116, 176) to 56 (IQR 28, 72) mg/dl), p < 0.001), there was an increase in CD34⁽⁺⁾/CD133⁽⁺⁾ and VEGFR-2⁽⁺⁾ cell levels (0.98% (IQR 0.37, 1.55) to 1.43% (IQR 0.90, 4.51), p = 0.002 and 0.66% (IQR 0.22, 0.99) to 1.53% (IQR 0.73, 2.70), p = 0.05, respectively). Functionally, increase in EPCs-CFUs was microscopically evident following treatment with PCSK9i (1 CFUs (IQR 0.0, 1.0) to 2.5 (IQR 1.5, 3), p < 0.001) with a concomitant increase in EPC's viability as demonstrated by an MTT assay (0.15 (IQR 0.11, 0.19) to 0.21 (IQR 0.18, 0.23), p < 0.001). VEGF levels increased following PCSK9i treatment (57 (IQR 18, 24) to 105 (IQR 43, 245), p = 0.006).

CONCLUSIONS

Patients with CVD treated with PCSK9i demonstrate higher levels of active cEPCs, reflecting the promotion of endothelial repair. These findings may represent a novel mechanism of action of PCSK9i.

Combined intake of glucose-and lipid-lowering medications further elevates plasma levels of PCSK9 in type 2 diabetes patients

BACKGROUND AND AIM

This study examined the status of plasma levels of protein convertase subtilisin/kexin 9 (PCSK9) in association with glucose-and lipid-lowering medications in subjects with type 2 diabetes (T2D).

METHODS

This study comprised 177 diabetics and 115 non-diabetic subjects recruited from the United Arab Emirates National Diabetes Study (UAEDIAB). Clinical and biomedical data were collected by standard techniques. Plasma levels of PCSK9 were determined using ELISA.

RESULTS

PCSK9 levels were higher in diabetics than non-diabetics (P < 0.001). Diabetics with disease duration >5 years, HbA1c > 7.0%, or male subjects, had significantly higher levels of PCSK9 than their counterparts (P < 0.05). Regression analysis revealed that HbA1c and age are predictors for PCSK9 in T2D subjects. Diabetic subjects with abnormal lipids profile on lipid-lowering medications had a higher level of PCSK9 compared to those with normal lipids profile (85.6 ± 40.5 vs. 63.7 ± 39.5 ng/ml, respectively; P < 0.01). Diabetics on combined intake of insulin and oral glucose-lowering drugs had higher levels of PCSK9 than those not taking any (86.1 ± 41.6 vs 69.7 ± 36.1 ng/ml, respectively; P < 0.05). The highest levels of PCSK9 however, were in diabetics on combined lipid- and glucose-lowering therapy when compared to those, not on any (96.2 ± 34.0 vs 66.0 ± 35.1 ng/ml, respectively; P < 0.01).

CONCLUSIONS

Age and HbA1c are the most predictors for the elevated levels of PCSK9 in Emirati T2D subjects. Combined therapy of glucose-and lipid-lowering medications further elevates plasma levels of PCSK9 in diabetic subjects.

Relation of Proprotein Convertase Subtilisin/Kexin Type 9 to Cardiovascular Outcomes in Patients Undergoing Percutaneous Coronary Intervention

The pharmacological inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) has been shown to drastically affect low-density lipoprotein cholesterol levels and associated cardiovascular diseases. However, the potential effectiveness of PCSK9 serum levels as a biomarker for cardiovascular risk remains unclear. Serum PCSK9 levels in patients who underwent percutaneous coronary intervention (PCI) may predict long-term outcomes. PCSK9 levels were measured in 749 consecutive patients with coronary artery disease undergoing PCI. These patients were classified into 2 groups according to their serum levels of PCSK9. The primary end point was a composite of the major adverse cardiac events (MACE), including cardiac death, myocardial infarction, stroke, and any revascularization. The median PCSK9 level was 302.82 ng/ml. During a median follow-up of 28.4 months, a total of 38 (5.1%) MACE was recorded, and 50 (6.7%) patients died from any cause. Multivariate Cox regression analysis showed that compared with a lower serum PCSK9 level, a higher serum PCSK9 level was independently associated with a higher rate of MACE (adjusted hazard ratio 2.290, 95% confidence interval 1.040 to 5.045, p = 0.040) and all-cause death (adjusted hazard ratio 2.511, 95% confidence interval 1.220 to 5.167, p = 0.026). Results were consistent after propensity-score matching (MACE, adjusted HR 2.236, 95% CI 1.011-5.350, p = 0.047; all-cause death, adjusted HR 2.826, 95% CI 1.258-6.349, p = 0.012). Baseline serum PCSK9 levels were associated with long-term cardiovascular clinical outcomes and mortality during the long-term follow-up after PCI in patients with coronary artery disease.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Sex-specific predictors of PCSK9 levels in a European population: The IMPROVE study

BACKGROUND AND AIMS

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is one of the key regulators of low-density lipoprotein cholesterol plasma levels. Circulating PCSK9, which differs between genders, represents a valid pharmacological target for preventing cardiovascular (CV) events. We aimed to investigate sex-related associations between PCSK9 plasma levels and biochemical and anthropomorphic factors, and familial and personal morbidities, in a large European cohort (n = 3673) of men (47.9%) and women (52.1%).

METHODS

Individuals (aged 54-79 years) free of CV diseases were enrolled in seven centers of five European countries: Finland, France, Italy, the Netherlands, and Sweden. PCSK9 plasma levels were measured by ELISA.

RESULTS

PCSK9 was higher in women than in men. Multiple linear regression analysis showed that latitude, sex, and treatments with statins and fibrates were the strongest predictors of PCSK9 in the whole group. These variables, together with triglycerides and high-density lipoprotein cholesterol, were also associated with PCSK9 in men or women. Mean corpuscular hemoglobin concentration and pack-years were PCSK9 independent predictors in women, whereas hypercholesterolemia and physical activity were independent predictors in men. The associations between PCSK9 and latitude, uric acid, diabetes, hypercholesterolemia and physical activity were significantly different in men and women (p_interaction <0.05 for all).

CONCLUSIONS

Besides confirming the association with lipids in the whole group, our study revealed previously unknown differences in PCSK9 predictors in men and women. These might be taken into account when defining individual risk for CV events and/or for refining PCSK9 lowering treatments.

Beyond cholesterol metabolism: The pleiotropic effects of proprotein convertase subtilisin/kexin type 9 (PCSK9). Genetics, mutations, expression, and perspective for long-term inhibition

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has a crucial role in lipid metabolism, particularly due to its function in low-density lipoprotein receptor degradation. Gain-of-function genetic mutations of PCSK9 result in autosomal dominant familial hypercholesterolemia, characterized by high levels of low-density lipoprotein cholesterol (LDL-C) and clinical signs of early atherosclerosis. In recent years, PCSK9 has become an important therapeutic target for cholesterol-lowering therapy. Particularly, its inhibition with monoclonal antibodies has shown excellent efficacy in decreasing LDL-C and reducing cardiovascular events. However, PCSK9, first identified in the brain, seems to be a ubiquitous protein with different tissue-specific functions also independent of cholesterol metabolism. Accordingly, it appears to be involved in the immune response, haemostasis, glucose metabolism, neuronal survival, and several other biological functions. This review provides a comprehensive overview of the genetics, biochemical structure, expression, and function of PCSK9 and discusses the potential implications of its long-term pharmacological inhibition.

Dyslipidaemias and Cardiovascular Disease: Focus on the Role of PCSK9 Inhibitors

Genetic, experimental and clinical studies have consistently confirmed that inhibition of Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) can result in significant lowering of LDL-C and two fully human PCSK9 monoclonal antibodies have received regulatory approval for use in highrisk patients. Co-administration of PCSK9 with statins has resulted in extremely low LDL-C levels with excellent short-term safety profiles. While results from Phase III clinical trials provided significant evidence about the role of PCSK9 inhibitors in reducing cardiovascular event rates, their impact on mortality remains less clear. PCSK9 inhibitor therapy can be considered for high-risk patients who are likely to experience significant cardiovascular risk reduction.

PCSK9 and atherosclerosis burden in the coronary arteries of patients undergoing coronary angiography

AIMS

To investigate the association between plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) concentrations, current acute coronary syndrome (ACS), coronary artery disease (CAD) presence, severity and extension and the burden of coronary calcifications in patients with suspected CAD.

METHODS AND RESULTS

One hundred and one patients, with or without current ACS, were recruited for this cross-sectional study. CAD presence was defined based on either the presence or absence of at least one significant (≥50%) CAD lesion (SCAD). CAD severity was classified according to the absence of coronary lesions, the presence of non-significant (<50%) CAD (MCAD) or SCAD in at least one major coronary artery. Patients with one, two or three significantly diseased major coronary arteries were defined as 1-SCAD, 2-SCAD and 3-SCAD, respectively. The cumulative length of SCAD lesions and the amount of calcifications in coronary arteries were estimated. Plasma PCSK9 concentrations were higher in patients with SCAD as compared to those without (p = .012). A significant increase in plasma PCSK9 concentrations was observed with greater CAD severity (p = .042). Higher plasma PCSK9 concentrations were found in 3-SCAD patients as compared to either 2-SCAD or 1-SCAD (p < .001). PCSK9 increased with the cumulative length of SCAD lesions and the burden of calcifications (p < .05 for both comparisons). Multivariable adjustment abolished the association between PCSK9 and either CAD presence or severity, but not the association between PCSK9 and the number of significantly diseased vessels, SCAD lesion length and the burden of coronary calcifications. ACS was associated with a borderline significant increase of plasma PCSK9 concentrations among patients not taking statins (p = .05).

CONCLUSION

Circulating PCSK9 concentrations discriminate patients with greater coronary atherosclerotic lesion extension and calcification, and are increased in patients with current ACS.

Circulating PCSK9 and cardiovascular events in FH patients with standard lipid-lowering therapy

BACKGROUND

Proprotein convertase subtilisin/kexin 9 (PCSK9) has been proposed as a novel target for coronary artery disease (CAD). Familial hypercholesterolemia (FH) is characterized by high prevalence of CAD and major cardiovascular events (MACEs). However, no data is available on the association between PCSK9 levels and MACEs in FH patients with standard lipid lowering therapy.

METHODS

A total of 338 consecutive heterozygous FH (Dutch Lipid Clinic Network score ≥ 6) was enrolled and followed up for the occurrence of MACEs. Multidetector CT and coronary angiography were performed to determine coronary artery calcification score (CACS) and Gensini score (GS). Multivariable Cox regression analyses were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). Plasma PCSK9 concentrations were determined by enzyme immunoassay.

RESULTS

PCSK9 was independently and positively associated CACS and GS at baseline. During a mean follow-up of 3 years, 33 (9.8%) events occurred. Patients with MACEs had higher median PCSK9 compared with those without (332.47 vs. 311.89 ng/mL, p = 0.038). Kaplan-Meier analysis revealed that patients with higher PCSK9 presented lower event-free survival (p = 0.0017). PCSK9 was statistically correlated with MACEs after adjusting for confounding factors, with the HR per SD being 1.86 (1.31-2.65) and 3.70 (1.16-11.82) for the highest tertile compared with the lowest tertile. Adding PCSK9 to Cox prediction model led to a statistical improvement in net reclassification and integrated discrimination.

CONCLUSION

Elevated levels of PCSK9 were positively associated with the development of CAD and future cardiovascular events, suggesting that measurement of PCSK9 concentration might be useful for cardiovascular risk stratification. Further studies are needed to confirm our results.

Association of PCSK9 plasma levels with metabolic patterns and coronary atherosclerosis in patients with stable angina

OBJECTIVE

Aim of this study was to evaluate the relationship of plasma PCSK9 with metabolic and inflammatory profile and coronary atherosclerotic burden in patients with suspected CAD enrolled in the EVINCI study.

METHODS

PCSK9 was measured in 539 patients (60.3 ± 8.6 years, 256 males) with symptoms of CAD characterized by risk factors, bio-humoral profiles, and treatment. N = 412 patients underwent coronary computed tomography angiography (CTA) to assess the presence and characteristics of coronary atherosclerosis. A CTA score, combining extent, severity, composition, and location of plaques was computed.

RESULTS

Patients were divided according to PCSK9 quartiles: I (< 136 ng/mL), II-III (136-266 ng/mL), and IV quartile (> 266 ng/mL). Compared with patients in quartile IV, patients in quartile I had a higher prevalence of the metabolic syndrome and higher values of body mass index. LDL- and HDL-cholesterol were significantly lower in patients in the quartile I than in those in quartile IV. Coronary CTA documented normal vessels in 30% and obstructive CAD in 35% of cases without differences among PCSK9 quartiles. Compared with patients with the highest levels, patients with the lowest PCSK9 levels had a higher CTA score mainly due to higher number of mixed non-obstructive coronary plaques. At multivariable analysis including clinical, medications, and lipid variables, PCSK9 was an independent predictor of the CTA score (coefficient - 0.129, SE 0.03, P < 0.0001), together with age, male gender, statins, interleukin-6, and leptin.

CONCLUSION

In patients with stable CAD, low PCSK9 plasma levels are associated with a particular metabolic phenotype (low HDL cholesterol, the metabolic syndrome, obesity, insulin resistance and diabetes) and diffuse non-obstructive coronary atherosclerosis. Trial registration ClinicalTrials.gov NCT00979199. Registered September 17, 2009.

Can metformin stabilize PCSK9 level in stable coronary artery disease patients treated with statins?

Introduction

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as an important marker of cardiovascular risk and a new target for therapeutic interventions. We aimed to study the influence of metformin on the level of circulating PCSK9 in patients with stable coronary artery disease (SCAD) and type 2 diabetes (T2DM) or metabolic syndrome (MetS), receiving moderate doses of statins used in routine clinical practice.

Material and methods

The study included 80 patients with T2DM or MetS receiving rosuvastatin for at least three months prior the study. MetS was diagnosed based on the Global Consensus Definition of the International Diabetes Federation (IDF). Serum level of PCSK9 was measured with an ELISA kit.

Results

Patients with T2DM or MetS, who took part in the research, were divided into 2 groups - those who received metformin prior the main study (21 patients - 1^st group) and patients who did not (59 patients - 2^nd group). Addition of metformin to the 3-month statin therapy of the 2nd group patients, divided into subgroup A (n = 27) with the addition of metformin and subgroup B (n = 29) without one, did not significantly affect the level of lipids. However, the level of circulating PCSK9 in subgroup A patients decreased, compared to subgroup B (p < 0.01). At the same time, ongoing metformin and rosuvastatin therapy in the 1^st group patients was not accompanied by a further decrease of the PCSK9 level.

Conclusions

The addition of metformin to ongoing rosuvastatin therapy did not significantly affect serum lipid levels, but stabilized the level of circulating PCSK9, compared with the group without metformin treatment.

Sex Differences Associated With Circulating PCSK9 in Patients Presenting With Acute Myocardial Infarction

A limited number of studies have explored whether the role of circulating proprotein convertase subtilisin/kexin type 9 (PCSK9) in the pathogenesis of acute myocardial infarction (AMI) is sex specific. The purpose of the present study was to examine sex differences in plasma PCSK9 in Chinese patients with AMI. In this study, a total of 281 records from patients presenting with AMI were analyzed.We compared hospital data and plasma PCSK9 levels by sex difference for inpatients presenting with AMI. After 1 year of follow-up, major adverse cardiac events(MACE) were recorded. A Cox proportional hazards model was used to calculate hazard ratios with 95% confidence intervals. We found that, compared with male groups, PCSK9 levels were higher in female patients not only for overall patients with AMI but also for patients with ST-elevation myocardial infarction (STEMI) (median: 273.6 [215.6–366.8] vs. 325.1 [247.5–445.3] ng/ml, P = 0.0136; 273.4 [215.6–369.7] vs. 317.1 [249.6–450.1], P = 0.0275, respectively). The cumulative incidence of cardiac death and 1-year MACE were significantly higher in the female group compared with male group (10% vs. 2.74%, P = 0.025; 15% vs. 4.11%, P = 0.0054, respectively). On multivariate Cox regression analysis, female sex, total triglyceride, glycosylated hemoglobin A, and homocysteic acid were independent risk factors of 1-year MACE. There was no significant correlation between PCSK9 and 1-year MACE in total AMI patients. In conclusion, PCSK9 levels and 1-year MACE were higher in women with AMI than in men with AMI, however, female sex but not PCSK9 were significant correlated with the 1-year MACE. The clinical implications of this finding are worthy of further investigations and must be confirmed in larger cohorts.

Changes in circulating pro-protein convertase subtilisin/kexin type 9 levels - experimental and clinical approaches with lipid-lowering agents

Regulation of pro-protein convertase subtilisin/kexin type 9 (PCSK9) by drugs has led to the development of a still small number of agents with powerful activity on low-density lipoprotein cholesterol levels, associated with a significant reduction of cardiovascular events in patients in secondary prevention. The Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects with Elevated Risk (FOURIER) and Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab (ODYSSEY OUTCOMES) studies, with the two available PCSK9 antagonists, i.e. evolocumab and alirocumab, both reported a 15% reduction in major adverse cardiovascular events. Regulation of PCSK9 expression is dependent upon a number of factors, partly genetic and partly associated to a complex transcriptional system, mainly controlled by sterol regulatory element binding proteins. PCSK9 is further regulated by concomitant drug treatments, particularly by statins, enhancing PCSK9 secretion but decreasing its stimulatory phosphorylated form (S688). These complex transcriptional mechanisms lead to variable circulating levels making clinical measurements of plasma PCSK9 for cardiovascular risk assessment a debated matter. Determination of total PCSK9 levels may provide a diagnostic tool for explaining an apparent resistance to PCSK9 inhibitors, thus indicating the need for other approaches. Newer agents targeting PCSK9 are in clinical development with a major interest in those with a longer duration of action, e.g. RNA silencing, allowing optimal patient compliance. Interest has been expanded to areas not only limited to low-density lipoprotein cholesterol reduction but also investigating other non-lipid pathways raising cardiovascular risk, in particular inflammation associated to raised high-sensitivity C-reactive protein levels, not significantly affected by the present PCSK9 antagonists.

Comparative effects of high-dose atorvastatin versus rosuvastatin on lipid parameters, oxidized low-density lipoprotein, and proprotein convertase subtilisin kexin 9 in acute coronary syndrome

AIM

Current guidelines recommend administration of high-dose statins in acute coronary syndrome (ACS). It has been reported that statins upregulate proprotein convertase subtilisin kexin 9 (PCSK9) mRNA expression and increase circulating PCSK9 levels. We aimed to compare the effects of high-dose atorvastatin and rosuvastatin on serum oxidized low-density lipoprotein (oxidized-LDL) and PCSK9 levels in statin-naive patients with ACS.

PATIENTS AND METHODS

One hundred and six patients with ACS were enrolled in this study. The patients were assigned randomly to receive atorvastatin (80 mg/day) or rosuvastatin (40 mg/day) by using a ratio of 1 : 1 in randomization. The levels of total cholesterol (TC), triglyceride, high-density lipoprotein cholesterol, LDL-cholesterol, oxidized-LDL, and PCSK9 were compared between groups after a 4-week treatment.

RESULTS

Our study population included 53 patients in the atorvastatin group (age: 58.13±11.30 years, 11.32% female) and 53 patients in the rosuvastatin group (age: 59.08±12.44 years, 15.09% female). In both groups, lipid parameters, oxidized-LDL, and PCSK9 values changed significantly according to the baseline following treatment. High-dose atorvastatin and rosuvastatin induced similar decreases in LDL-cholesterol, oxidized-LDL, and triglyceride levels and similarly increased in high-density lipoprotein cholesterol and PCSK9 levels (P>0.05).

CONCLUSION

We showed that atorvastatin and rosuvastatin treatment regimens have comparable effects on lipid parameters and PCSK9 levels in ACS patients.

Long-term exposure to air pollution raises circulating levels of proprotein convertase subtilisin/kexin type 9 in obese individuals

Aims

Exposure to airborne particulate matter has been consistently associated with early death and increased morbidity, particularly raising the risk of cardiovascular disease. Obesity, one of the leading cardiovascular disease risk factors, increases susceptibility to the adverse effects of particulate matter exposure. Proprotein convertase subtilisin/kexin type 9 has been related to a large number of cardiovascular risk factors, e.g. atherogenic lipoproteins, arterial stiffness and platelet activation. Thus, the present study was aimed at evaluating, in a series of obese individuals, the effects of particulate matter less than 10 µm in diameter (PM10) on proprotein convertase subtilisin/kexin type 9 circulating levels.

Methods and results

In 500 obese subjects, participating in the cross-sectional Susceptibility to Particle Health Effects, miRNAs and Exosomes (SPHERE) study, we evaluated the effects of long- and short-term PM10 exposure on circulating proprotein convertase subtilisin/kexin type 9 levels. In the studied individuals (body mass index: 33.3 ± 5.2 kg/m2) with an annual average PM10 exposure of 40.12 ± 4.71 µg/m3, proprotein convertase subtilisin/kexin type 9 levels were 248.7 ± 78.6 ng/mL. In univariate analysis, PM10 exposure (annual average) was associated with proprotein convertase subtilisin/kexin type 9 levels (β=1.83, standard error = 0.75, p = 0.014). Interestingly, in a multivariable linear regression model, this association was observed only for carriers of lower concentrations of interferon-γ, whereas it was lost in the presence of higher interferon-γ levels. Proprotein convertase subtilisin/kexin type 9 levels were positively associated with the Framingham Risk Score, which was raised by 15.8% for each 100 ng/ml rise of proprotein convertase subtilisin/kexin type 9.

Conclusions

In obese individuals, more sensitive to the damaging effects of environmental air pollution, PM10 exposure positively associates with proprotein convertase subtilisin/kexin type 9 plasma levels especially in those with low levels of interferon-γ. 

Acute-Phase Plasma PCSK9 Levels and Recurrent Cardiovascular Events in a Chinese Acute Myocardial Infarction Cohort

Background: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a promising target for lowering plasma low-density lipoprotein cholesterol and preventing cardiovascular (CV) disease. Whether plasma PCSK9 measured during the acute phase predicts recurrent CV events in patients with acute myocardial infarction (AMI) remains unresolved. Methods and Results: Plasma PCSK9 levels were measured in 1,646 patients with AMI from the China PEACE-Prospective AMI Study at the acute phase. Additionally, 248 patients were resampled and measured at 1 month post-AMI. Associations of acute-phase PCSK9 tertiles with clinical characteristics and recurrent CV events within 1 year were assessed. Female gender (OR 1.94, 95% CI 1.24–3.03), premature coronary heart disease (CHD; OR 2.12, 95% CI 1.37–3.26), higher high-sensitivity C-reactive protein (OR 1.67, 95% CI 1.44–1.95), and higher triglycerides (OR 1.46, 95% CI 1.03–2.09) were associated with higher baseline PCSK9. Plasma PCSK9 levels in the highest tertile (versus lowest) did not have an increased risk of 1-year recurrent CV events in the AMI cohort (HR 0.78, 95% CI 0.52–1.16) or any subgroup. There was also no association between percentage changes in PCSK9 over the first month and 1-year recurrent events, although there was a trend of differences between patients in the upper versus lower tertiles. Conclusion: Plasma PCSK9 levels measured during the acute phase were associated with high-sensitivity C-reactive protein, triglycerides, premature CHD, and gender in patients with AMI but did not predict recurrent CV events within 1 year. Dynamic changes in PCSK9 suggested a trend yet no significance value in predicting recurrent CV events.

PCSK9: From Basic Science Discoveries to Clinical Trials

Unknown 15 years ago, PCSK9 (proprotein convertase subtilisin/kexin type 9) is now common parlance among scientists and clinicians interested in prevention and treatment of atherosclerotic cardiovascular disease. What makes this story so special is not its recent discovery nor the fact that it uncovered previously unknown biology but rather that these important scientific insights have been translated into an effective medical therapy in record time. Indeed, the translation of this discovery to novel therapeutic serves as one of the best examples of how genetic insights can be leveraged into intelligent target drug discovery. The PCSK9 saga is unfolding quickly but is far from complete. Here, we review major scientific understandings as they relate to the role of PCSK9 in lipoprotein metabolism and atherosclerotic cardiovascular disease and the impact that therapies designed to inhibit its action are having in the clinical setting.

Plasma proprotein-convertase-subtilisin/kexin type 9 (PCSK9) and cardiovascular events in type 2 diabetes

AIM

To investigate whether plasma concentrations of proprotein-convertase-subtilisin/kexin type 9 (PCSK9) were associated with cardiovascular (CV) events in two cohorts of patients with type 2 diabetes mellitus.

METHODS

We considered patients from the DIABHYCAR (n = 3137) and the SURDIAGENE (n = 1468) studies. Baseline plasma PCSK9 concentration was measured using an immunofluorescence assay. In post hoc, but preplanned, analyses we assessed the relationship between PCSK9 and the following endpoints: (1) a combined endpoint of major CV events: CV death, non-fatal myocardial infarction (MI), stroke and heart failure-related hospital admission; (2) a composite of all CV events: MI, stroke, heart failure-related hospital admission, coronary/peripheral angioplasty or bypass, CV death; (3) MI; (4) stroke/transient ischaemic attack (TIA); and (5) CV death.

RESULTS

In the DIABHYCAR study, plasma PCSK9 tertiles were associated with the incidence of MI, all CV events and stroke/TIA (P for trend <.05). In adjusted Cox analysis, plasma PCSK9 was associated, independently of classic risk factors, with the incidence of major CV events (hazard ratio [HR] for 1-unit increase of log[PCSK9] 1.28 [95% confidence interval {CI} 1.06-1.55]), the incidence of MI (HR 1.66 [95% CI 1.05-2.63]), and the incidence of all CV events (HR 1.22 [95% CI 1.04-1.44]), but not with CV death. Plasma PCSK9 was not associated with the incidence of CV disease in the participants of the SURDIAGENE study with high CV risk treated with statins and insulin.

CONCLUSIONS

We found that PCSK9 was inconsistently associated with CV events in populations with type 2 diabetes. The association may depend on the level of CV risk and the background treatment.

Ossabaw Pigs With a PCSK9 Gain-of-Function Mutation Develop Accelerated Coronary Atherosclerotic Lesions: A Novel Model for Preclinical Studies

BACKGROUND

Ossabaw pigs are unique miniature swine with genetic predisposition to develop metabolic syndrome and coronary atherosclerosis after extended periods receiving atherogenic diets. We have hypothesized that transgenic Ossabaw swine expressing chimp PCSK9 (proprotein convertase subtilisin-like/kexin type 9) containing the D374Y gain of function would develop familial hypercholesterolemia and coronary artery plaques more rapidly than Landrace swine with the same transgene.

METHODS AND RESULTS

Ossabaw and Landrace PCSK9 gain-of-function founders were generated by Sleeping Beauty transposition and cloning. Histopathologic findings in the Ossabaw founder animal showed more advanced plaques and higher stenosis than in the Landrace founder, underscoring the Ossabaw genetic predisposition to atherosclerosis. We chose to further characterize the Ossabaw PCSK9 gain-of-function animals receiving standard or atherogenic diets in a 6-month longitudinal study using computed tomography, magnetic resonance (MR) imaging, intravascular ultrasound, and optical coherence tomography, followed by pathological analysis of atherosclerosis focused on the coronary arteries. The Ossabaw model was consistently hypercholesterolemic, with or without dietary challenge, and by 6 months had consistent and diffuse fibrofatty or fibroatheromatous plaques with necrosis, overlying fibrous caps, and calcification in up to 10% of coronary plaques.

CONCLUSIONS

The Ossabaw PCSK9 gain-of-function model provides consistent and robust disease development in a time frame that is practical for use in preclinical therapeutic evaluation to drive innovation. Although no animal model perfectly mimics the human condition, this genetic large-animal model is a novel tool for testing therapeutic interventions in the context of developing and advanced coronary artery disease.

High circulating proprotein convertase subtilisin/Kexin type 9 concentration associates with cardiovascular risk: A meta-analysis of cohort studies

Whether the baseline circulating proprotein convertase subtilisin/Kexin type 9 (PCSK9) concentration associates with cardiovascular risk remains uncertain. This study aimed to investigate the predictive value of circulating PCSK9 in cardiovascular risk prediction.Relevant studies were searched through the MEDLINE, EMBASE, and Cochrane Library databases. The relative risk (RR) and 95% confidence interval (CI) were pooled to evaluate the association between the circulating PCSK9 concentration and cardiovascular risk. Dose-response meta-analysis was also performed in this study.A total of 11 cohort studies with 13,761 participants were included. The RR for cardiovascular risk was 1.25 (95% CI: 1.14-1.38, P < .001, I = 25%) while compared highest to lowest PCSK9 concentration. Subgroup meta-analysis, which sorted by ethnicity, base risk characteristic, and follow-up time, presented consistent results that there was a pronounced association between highest PCSK9 concentration and cardiovascular risk, such relationship was not significant in the statin-taking subjects. Seven studies were included in dose-response meta-analysis, and a nonlinear association between PCSK9 concentration and cardiovascular risk was observed [(χ test for nonlinearity = 6.7, (df = 2), P = .036].This study suggests that high circulating PCSK9 concentration associates with significantly increased cardiovascular risk, and demonstrates for the first time that it is a nonlinear dose-response association between circulating PCSK9 concentration and cardiovascular risk. These results provide the evidence that PCSK9 is an independent risk factor beyond the traditional cardiovascular risk factors and indicates a potential role of PCSK9 measurement for medical decisions. The clinical value of PCSK9 measurement and the identification of risk threshold should be confirmed in appropriately designed clinical trials.

Anti-PCSK9 antibodies for the treatment of heterozygous familial hypercholesterolemia: patient selection and perspectives

Heterozygous familial hypercholesterolemia (FH) is a genetic disorder characterized by high low-density lipoprotein cholesterol levels from birth, which exposes the arteries to high levels of atherogenic lipoproteins lifelong and results in a significantly increased risk of premature cardiovascular events. The diagnosis of FH, followed by an appropriate and early treatment is critical to reduce the cardiovascular burden in this population. Phase I–III clinical trials showed the benefit of proprotein convertase subtilisin kexin 9 inhibitors, both alirocumab and evolocumab, in these patients with an average low-density lipoprotein cholesterol reduction ranging from −40% to −60%. The aim of this review is to address the unmet needs in cholesterol management, elucidate the biology and the clinical benefit of proprotein convertase subtilisin kexin 9 inhibition and finally discuss the open gaps and future directions in the treatment of patients with heterozygous FH.