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

Impact of PCSK9 inhibitors on bleeding and adverse outcomes in post-PCI patients undergoing antiplatelet therapy: A real-world cohort study

BACKGROUND

The relationship between low-density lipoprotein cholesterol (LDL-C) levels and bleeding risk during antiplatelet therapy post-percutaneous coronary intervention (PCI) is uncertain, and the effect of proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) on bleeding risk is unknown.

METHODS

This retrospective cohort study analyzed data from 85,464 PCI patients on oral antiplatelet therapy across 82 Tianjin hospitals from 2017 to 2023, using 1:1 PSM. The primary outcome was Bleeding Academic Research Consortium (BARC) type 3 or 5 bleeding within one year. Kaplan-Meier survival curves and Cox regression models were employed to assess the association between PCSK9i and clinical outcomes, with Win-ratio analysis used for composite endpoints.

RESULTS

Among 85,464 patients (64 % male), 1979 (2.32 %) received PCSK9i were followed for one year. After PSM, a balanced cohort of 1951 patients in both the PCSK9i and control groups was established. Multivariate cox regression analysis revealed that patients on PCSK9i had significantly reduced risks of NACE (aHR: 0.674, 95 %CI: 0.528-0.859, P = 0.001), MACCE (aHR: 0.674, 95 %CI: 0.524-0.866, P = 0.002), all-cause death (aHR: 0.501, 95 %CI: 0.275-0.915, P = 0.025), and revascularization (aHR: 0.604, 95 %CI: 0.419-0.872, P = 0.007) at one year. No significant differences were found in other endpoints. The hierarchical outcome significantly favored PCSK9i (matched win ratio 0.634, 95 % CI: 0.584-0.689, P < 0.001).

CONCLUSIONS

PCSK9i therapy did not increase bleeding risk and was associated with lower risks of adverse outcomes compared to the control group.

Circulating Endothelial Progenitor Cells in Patients with Established Cardiovascular Disease Treated with PCSK9 Monoclonal Antibodies

Background

The role of circulating endothelial progenitor cells (cEPCs) in vascular repair and their association to cardiovascular protection is well established.

Objectives

We examined the effect of proprotein convertase subtilisin kexin type 9 monoclonal antibodies (PCSK9 mAb) on cEPCs in adults with hypercholesterolemia and cardiovascular disease, aiming to establish a pleotropic class effect.

Methods

Non-interventional prospective study in patients with cardiovascular disease treated with either evolocumab or alirocumab. Patients were sampled for cEPCs at baseline, 1- and 3-months following initiation of PCSK9 mAb. cEPCs were assessed using flow cytometry by expression of CD34/CD133 and vascular endothelial growth factor receptor (VEGFR)-2, and functionally by formation of colony forming units (CFUs) and by Mitochondrial Tetrazolium (MTT) assay, indicative of cEPCs viability.

Results

51 patients (median age 67 (IQR 63,74) years;63 % male, median low-density lipoprotein-cholesterol (LDL-C) 125 (102,165) mg/dL) were initiated on PCSK9 mAb therapy (evolocumab n = 22, alirocumab n = 29) for secondary prevention. Following 3-month treatment with PCSK9 mAb, there was an increase in CD34(+)VEGFR-2(+) and CD133(+)VEGFR-2(+) levels (0.50 % [IQR 0.30,1.04] to 1.36 % [0.89, 1.73], p < 0.001 and 0.57 % [0.25,0.88] to 1.18 % [0.74,1.66], p < 0.001, respectively). Functionally, increase in EPCs-CFUs was evident (0.5 [0.0,1.0] to 2.0 [1.5,2.5], p < 0.001) with concomitant increase in MTT (0.11 [0.09,0.15] to 0.17 [0.12,0.21], p < 0.001). Stratifying by PCSK9 mAb, both agents were associated with an increase in cEPCs level and function.

Conclusions

In hypercholesterolemic patients with cardiovascular disease treated with PCSK9 mAb, there is an increase in cEPCs levels and function from baseline levels. These findings, which persist in both evolocumab and alirocumab, might suggest a novel pleiotropic class effect.

The effect of empagliflozin on circulating endothelial progenitor cells in patients with diabetes and stable coronary artery disease

BACKGROUND

Diabetes mellitus (DM) is associated with premature atherosclerotic disease, coronary artery disease (CAD) and chronic heart failure (HF), leading to increased morbidity and mortality. Sodium-Glucose Co-transporter 2 Inhibitors (SGLT2i) exhibit cardioprotective benefits beyond glucose lowering, reducing the risk of major cardiovascular events (MACE) and HF hospitalizations in patients with DM and CAD. Endothelial progenitor cells (EPCs) are bone marrow-derived cells involved in vascular repair, mobilized in response to vascular injury. The number and function of circulating EPCs (cEPCs) are negatively affected by cardiovascular risk factors, including DM. This study aimed to examine the response of cEPCs to SGLT2i treatment in DM patients with stable CAD.

METHODS

A prospective single-center study included patients with DM and stable CAD who were started on an SGLT2i (empagliflozin). Peripheral blood samples were collected at baseline, 1 month, and 3 months to evaluate cEPC levels and function by flow cytometry, immunohistochemistry and MTT assays.

RESULTS

Eighteen patients were included in the study (median age 73, (IQR 69, 77) years, 67% male). After 1 month of treatment with empagliflozin, there was no significant change in cEPCs level or function. However, following 3 months of treatment, a significant increase was observed both in cell levels (CD34(+)/VEGFR-2(+): from 0.49% (IQR 0.32, 0.64) to 1.58% (IQR 0.93, 1.82), p = 0.0006; CD133(+)/VEGFR-2(+): from 0.38% (IQR 0.27, 0.6) to 0.82% (IQR 0.7, 1.95), p = 0.0001) and in cell function (from 0.25 CFUs (IQR 0, 0.5) at baseline, to 2 CFUs (IQR 1, 2) at 3 months, p = 0.0012).

CONCLUSIONS

Empagliflozin treatment in patients with DM and stable CAD increases cEPC levels and function, implying a cardioprotective mechanism. These findings highlight the potential of SGLT2i in treating cardiovascular diseases, warranting further research to explore these effects and their long-term implications.

Effect of adding PCSK9 inhibitors to lipid-lowering interventions on arterial stiffness: A systematic review and meta-analysis

BACKGROUND

Atherosclerosis, a leading cause of mortality, necessitates effective management of hypercholesterolemia, specifically elevated low-density lipoprotein cholesterol (LDL-C). The emergence of proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) has revolutionised lipid-lowering. PCSK9i demonstrates substantial LDL-C reduction and cardiovascular benefits, particularly in statin-intolerant or nonresponsive individuals. However, the potential pleiotropic effects of PCSK9i, especially on arterial stiffness, remain a subject of investigation. This systematic review and meta-analysis seek to provide a nuanced understanding of the potential pleiotropic effects of PCSK9i, specifically on arterial health. The primary objective was to analyse the influence of PCSK9i on arterial stiffness, extending beyond traditional lipid-lowering metrics and contributing to a more comprehensive approach to cardiovascular risk reduction.

METHODS

A systematic search was conducted across major databases, clinical trial registries and grey literature. Inclusion criteria comprised adults in prospective cohort studies undergoing PCSK9i augmentation in lipid-lowering therapy, with a focus on arterial stiffness measured by pulse wave velocity (PWv). Random-effects meta-analyses, sensitivity analyses and meta-regression models were employed to assess the pooled effect of adding PCSK9i to lipid-lowering interventions on arterial stiffness.

RESULTS

Five studies (158 participants) met the inclusion criteria, demonstrating a significant reduction in PWv (mean difference: -2.61 m/s [95% CI: -3.70, -1.52]; ES: -1.62 [95% CI: -2.53, -.71]) upon adding PCSK9i to lipid-lowering interventions. Subgroup analysis and meta-regression models suggested potential sex-based and baseline PWv-dependent variations, emphasising patient-specific characteristics.

CONCLUSION

The meta-analysis provides robust evidence that adding PCSK9i to lipid-lowering interventions significantly improves arterial stiffness, indicating broader vascular benefits beyond LDL-C reduction.

Effects of PCSK9 on thrombosis and haemostasis in a variety of metabolic states: Lipids and beyond (Review)

Proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors are widely recognised as being able to induce a potent reduction in low‑density lipoprotein‑cholesterol. An increasing number of studies have suggested that PCSK9 also influences the haemostatic system by altering platelet function and the coagulation cascade. These findings have significant implications for anti‑PCSK9 therapy in patients with specific coagulation conditions, including expanded indications, dose adjustments and drug interactions. The present review summarises the changes in PCSK9 levels in individuals with liver diseases, chronic kidney diseases, diabetes mellitus, cancer and other disease states, and discusses their impact on thrombosis and haemostasis. Furthermore, the structure, effects and regulatory mechanisms of PCSK9 on platelets, coagulation factors, inflammatory cells and endothelial cells during coagulation and haemostasis are described.

Endothelial progenitor cells as biomarkers of diabetes-related cardiovascular complications

Diabetes mellitus (DM) constitutes a chronic metabolic disease characterized by elevated levels of blood glucose which can also lead to the so-called diabetic vascular complications (DVCs), responsible for most of the morbidity, hospitalizations and death registered in these patients. Currently, different approaches to prevent or reduce DM and its DVCs have focused on reducing blood sugar levels, cholesterol management or even changes in lifestyle habits. However, even the strictest glycaemic control strategies are not always sufficient to prevent the development of DVCs, which reflects the need to identify reliable biomarkers capable of predicting further vascular complications in diabetic patients. Endothelial progenitor cells (EPCs), widely known for their potential applications in cell therapy due to their regenerative properties, may be used as differential markers in DVCs, considering that the number and functionality of these cells are affected under the pathological environments related to DM. Besides, drugs commonly used with DM patients may influence the level or behaviour of EPCs as a pleiotropic effect that could finally be decisive in the prognosis of the disease. In the current review, we have analysed the relationship between diabetes and DVCs, focusing on the potential use of EPCs as biomarkers of diabetes progression towards the development of major vascular complications. Moreover, the effects of different drugs on the number and function of EPCs have been also addressed.

Rationale and design of a randomized controlled trial: The effect of intensive lipid-lowering therapy with PCSK9 inhibitor on endothelial-coverage of stent strut after percutaneous coronary intervention (PCI) for patients with acute coronary syndrome (ACS): Optical coherence tomography (OCT) study (PIECES-OCT study)

BACKGROUND

For the patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI), dual antiplatelet therapy (DAPT) for at least 1 year is recommended in the guidelines to minimize the risk of stent thrombosis. Persistently uncovered stent strut means delayed neointima formation and extend the window of time in which the stent is prone to thrombosis. Previous studies showed that statins could improve post-stenting strut endothelial coverage for patients undergoing PCI. However, there are lack of evidences on whether early initiation of proprotein convertase subtilisin/Kexin type 9 monoclonal antibody (PCSK9mAb) after PCI in ACS patients can further improve the rate of stent strut coverage on the background of oral lipid-lowering therapy (LLT).

METHODS

This is a single-center, randomized trial to enroll 36 patients undergoing PCI with a clinical diagnosis of non-ST-segment elevation ACS. The baseline level of low-density lipoprotein cholesterol (LDL-C) of these patients are between 1.4 mmol/L and 3.4 mmol/L. Patients will be assigned to intensive lipid-lowering therapy (LLT) with PCSK9mAb group and conventional LLT without PCSK9mAb group for 12 weeks in a clinical follow-up setting according to 1: 1 randomization. the rate of stent strut endothelial coverage by optical coherence tomography (OCT) examination at 12 weeks after enrollment between the groups will be compared.

CONCLUSION

This will be the first study to investigate changes in the rate of stent strut endothelial coverage under intensive LLT with PCSK9mAb by OCT examination in ACS patients undergoing PCI. The finding of this study will provide clinical evidence for future research about the hypothesis of a novel strategy of "intensive LLT (PCSK9mAb + statin ± ezetimibe) combined with shortened DAPT duration" for ACS patients undergoing PCI.Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: ChiCTR2200063395.

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.

Non-Lipid Effects of PCSK9 Monoclonal Antibodies on Vessel Wall

Elevated low density lipoprotein (LDL) cholesterol and lipoprotein(a) (Lp(a)) levels have an important role in the development and progression of atherosclerosis, followed by cardiovascular events. Besides statins and other lipid-modifying drugs, PCSK9 monoclonal antibodies are known to reduce hyperlipidemia. PCSK9 monoclonal antibodies decrease LDL cholesterol levels through inducing the upregulation of the LDL receptors and moderately decrease Lp(a) levels. In addition, PCSK9 monoclonal antibodies have shown non-lipid effects. PCSK9 monoclonal antibodies reduce platelet aggregation and activation, and increase platelet responsiveness to acetylsalicylic acid. Evolocumab as well as alirocumab decrease an incidence of venous thromboembolism, which is associated with the decrease of Lp(a) values. Besides interweaving in haemostasis, PCSK9 monoclonal antibodies play an important role in reducing the inflammation and improving the endothelial function. The aim of this review is to present the mechanisms of PCSK9 monoclonal antibodies on the aforementioned risk factors.

The Role of Endothelial Progenitor Cells in Atherosclerosis and Impact of Anti-Lipemic Treatments on Endothelial Repair

Cardiovascular complications are associated with advanced atherosclerosis. Although atherosclerosis is still regarded as an incurable disease, at least in its more advanced stages, the discovery of endothelial progenitor cells (EPCs), with their ability to replace old and injured cells and differentiate into healthy and functional mature endothelial cells, has shifted our view of atherosclerosis as an incurable disease, and merged traditional theories of atherosclerosis pathogenesis with evolving concepts of vascular biology. EPC alterations are involved in the pathogenesis of vascular abnormalities in atherosclerosis, but many questions remain unanswered. Many currently available drugs that impact cardiovascular morbidity and mortality have shown a positive effect on EPC biology. This review examines the role of endothelial progenitor cells in atherosclerosis development, and the impact standard antilipemic drugs, including statins, fibrates, and ezetimibe, as well as more novel treatments such as proprotein convertase subtilisin/kexin type 9 (PCSK9) modulating agents and angiopoietin-like proteins (Angtpl3) inhibitors have on EPC biology.

Reconstituted HDL-apoE3 promotes endothelial cell migration through ID1 and its downstream kinases ERK1/2, AKT and p38 MAPK

INTRODUCTION

Atherosclerotic Coronary Artery Disease (ASCAD) is the leading cause of mortality worldwide. Novel therapeutic approaches aiming to improve the atheroprotective functions of High Density Lipoprotein (HDL) include the use of reconstituted HDL forms containing human apolipoprotein A-I (rHDL-apoA-I). Given the strong atheroprotective properties of apolipoprotein E3 (apoE3), rHDL-apoE3 may represent an attractive yet largely unexplored therapeutic agent.

OBJECTIVE

To evaluate the atheroprotective potential of rHDL-apoE3 starting with the unbiased assessment of global transcriptome effects and focusing on endothelial cell (EC) migration as a critical process in re-endothelialization and atherosclerosis prevention. The cellular, molecular and functional effects of rHDL-apoE3 on EC migration-associated pathways were assessed, as well as the potential translatability of these findings in vivo.

METHODS

Human Aortic ECs (HAEC) were treated with rHDL-apoE3 and total RNA was analyzed by whole genome microarrays. Expression and phosphorylation changes of key EC migration-associated molecules were validated by qRT-PCR and Western blot analysis in primary HAEC, Human Coronary Artery ECs (HCAEC) and the human EA.hy926 EC line. The capacity of rHDL-apoE3 to stimulate EC migration was assessed by wound healing and transwell migration assays. The contribution of MEK1/2, PI3K and the transcription factor ID1 in rHDL-apoE3-induced EC migration and activation of EC migration-related effectors was assessed using specific inhibitors (PD98059: MEK1/2, LY294002: PI3K) and siRNA-mediated gene silencing, respectively. The capacity of rHDL-apoE3 to improve vascular permeability and hypercholesterolemia in vivo was tested in a mouse model of hypercholesterolemia (apoE KO mice) using Evans Blue assays and lipid/lipoprotein analysis in the serum, respectively.

RESULTS

rHDL-apoE3 induced significant expression changes in 198 genes of HAEC mainly involved in re-endothelialization and atherosclerosis-associated functions. The most pronounced effect was observed for EC migration, with 42/198 genes being involved in the following EC migration-related pathways: 1) MEK/ERK, 2) PI3K/AKT/eNOS-MMP2/9, 3) RHO-GTPases, 4) integrin. rHDL-apoE3 induced changes in 24 representative transcripts of these pathways in HAEC, increasing the expression of their key proteins PIK3CG, EFNB2, ID1 and FLT1 in HCAEC and EA.hy926 cells. In addition, rHDL-apoE3 stimulated migration of HCAEC and EA.hy926 cells, and the migration was markedly attenuated in the presence of PD98059 or LY294002. rHDL-apoE3 also increased the phosphorylation of ERK1/2, AKT, eNOS and p38 MAPK in these cells, while PD98059 and LY294002 inhibited rHDL-apoE3-induced phosphorylation of ERK1/2, AKT and p38 MAPK, respectively. LY had no effect on rHDL-apoE3-mediated eNOS phosphorylation. ID1 siRNA markedly decreased EA.hy926 cell migration by inhibiting rHDL-apoE3-triggered ERK1/2 and AKT phosphorylation. Finally, administration of a single dose of rHDL-apoE3 in apoE KO mice markedly improved vascular permeability as demonstrated by the reduced concentration of Evans Blue dye in tissues such as the stomach, the tongue and the urinary bladder and ameliorated hypercholesterolemia.

CONCLUSIONS

rHDL-apoE3 significantly enhanced EC migration in vitro, predominantly via overexpression of ID1 and subsequent activation of MEK1/2 and PI3K, and their downstream targets ERK1/2, AKT and p38 MAPK, respectively, and improved vascular permeability in vivo. These novel insights into the rHDL-apoE3 functions suggest a potential clinical use to promote re-endothelialization and retard development of atherosclerosis.

Endogenous PCSK9 may influence circulating CD45neg/CD34bright and CD45neg/CD34bright/CD146neg cells in patients with type 2 diabetes mellitus

Protease proprotein convertase subtilisin/kexin type 9 (PCSK9) is a regulator of LDL cholesterol clearance and has been associated with cardiovascular risk. PCSK9 inhibitors increase in vivo circulating endothelial progenitor cells (EPCs), a subtype of immature cells involved in ongoing endothelial repair. We hypothesized that the effect of PCSK9 on vascular homeostasis may be mediated by EPCs in patients with or without type 2 diabetes mellitus (T2DM). Eighty-two patients (45 with, 37 without T2DM) at high cardiovascular risk were enrolled in this observational study. Statin treatment was associated with higher circulating levels of PCSK9 in patients with and without T2DM (p < 0.001 and p = 0.036) and with reduced CD45neg/CD34bright (total EPC compartment) (p = 0.016) and CD45neg/CD34bright/CD146neg (early EPC) (p = 0.040) only among patients with T2DM. In the whole group of patients, statin treatment was the only independent predictor of low number of CD45neg/CD34bright (β = - 0.230; p = 0.038, adjusted R2 = 0.041). Among T2DM patients, PCSK9 circulating levels were inversely related and predicted both the number of CD45neg/CD34bright (β = - 0.438; p = 0.003, adjusted R2 = 0.173), and CD45neg/CD34bright/CD146neg (β = - 0.458; p = 0.002, adjusted R2 = 0.191) independently of age, gender, BMI and statin treatment. In high-risk T2DM patients, high endogenous levels of PCSK9 may have a detrimental effect on EPCs by reducing the endothelial repair and worsening the progression of atherothrombosis.