The effect of a platelet cholesterol modulation on the acetylsalicylic acid-mediated blood platelet inhibition in hypercholesterolemic patients

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.

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.

Antiplatelet Effects of PCSK9 Inhibitors in Primary Hypercholesterolemia

Proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors are a novel group of hypolipidemic drugs that are recommended particularly for high-risk hypercholesterolemia patients, including those with primary hypercholesterolemia (PH), where lifelong exposure to high low-density lipoprotein (LDL) cholesterol levels results in an elevated risk of atherosclerosis at an early age. The onset and progression of atherosclerosis is significantly influenced by activated platelets. Oxidized LDL influences platelet activation by interacting with their surface receptors and remodeling the composition of their cell membrane. This results in platelet aggregation, endothelial cell activation, promotion of inflammation and oxidative stress, and acceleration of lipid accumulation in atherosclerotic plaques. PCSK9 inhibitors reduce platelet activation by both significantly lowering LDL levels and reducing the LDL receptor-mediated activation of platelets by PCSK9. They also work synergistically with other hypolipidemic and antithrombotic drugs, including statins, ezetimibe, acetylsalicylic acid, clopidogrel, and ticagrelor, which enhances their antiplatelet and LDL-lowering effects. In this review, we summarize the currently available evidence on platelet hyperreactivity in PH, the effects of PCSK9 inhibitors on platelets, and their synergism with other drugs used in PH therapy.

Effect of Statins on Platelet Activation and Function: From Molecular Pathways to Clinical Effects

Purpose

Statins are a class of drugs widely used in clinical practice for their lipid-lowering and pleiotropic effects. In recent years, a correlation between statins and platelet function has been unveiled in the literature that might introduce new therapeutic indications for this class of drugs. This review is aimed at summarizing the mechanisms underlying statin-platelet interaction in the cardiologic scenario and building the basis for future in-depth studies.

Methods

We conducted a literature search through PubMed, Embase, EBSCO, Cochrane Database of Systematic Reviews, and Web of Science from their inception to June 2020.

Results

Many pathways could explain the interaction between statins and platelets, but the specific effect depends on the specific compound. Some could be mediated by enzymes that allow the entry of drugs into the cell (OATP2B1) and others by enzymes that mediate their activation (PLA2, MAPK, TAX2, PPARs, AKT, and COX-1), recruitment and adhesion (LOX-1, CD36, and CD40L), or apoptosis (BCL2). Statins also appear to have a synergistic effect with aspirin and low molecular weight heparins. Surprisingly, they seem to have an antagonistic effect with clopidogrel.

Conclusion

There are many pathways potentially responsible for the interactions between statins and platelets. Their effect appears to be closely related, and each single effect can be barely measured. Also, the same compound might have complex downstream signaling with potentially opposite effects, i.e., beneficial or deleterious. The multiple clinical implications that can be derived as a result of this interaction, however, represent an excellent reason to develop future in-depth studies.

PCSK9 Inhibitors and Neurocognitive Adverse Drug Reactions: Analysis of Individual Case Safety Reports from the Eudravigilance Database

Introduction

Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9Is) were associated with a risk of neurocognitive adverse drug reactions (ADRs).

Objective

We aimed to investigate the occurrence of neuropsychiatric ADRs related to PCSK9Is.

Methods

We analyzed Individual Case Safety Reports (ICSRs) sent through the European pharmacovigilance database that reported alirocumab or evolocumab as the suspected drug and at least one neurological or psychiatric ADR. The reporting odds ratio (ROR) was computed to compare the probability of reporting ICSRs with neuropsychiatric ADRs between alirocumab, evolocumab and statins.

Results

Overall, 2041 ICSRs with alirocumab and/or evolocumab as the suspected drug described the occurrence of neuropsychiatric ADRs. The most reported preferred terms for both drugs were headache, insomnia and depression. No difference between alirocumab and evolocumab was observed for the RORs of ICSRs with ADRs belonging to the System Organ Classes (SOCs) ‘Nervous system disorders’ or ‘Psychiatric disorders’ (ROR 1.02, 95% confidence interval 0.91–1.14; and 1.12, 95% CI 0.94–1.34, respectively), while evolocumab and alirocumab had a higher reporting probability of ICSRs with ADRs belonging to the SOC ‘Nervous system disorders’ compared with atorvastatin and fluvastatin. A lower reporting probability was instead found for ICSRs with ADRs belonging to the SOC ‘Psychiatric disorders’ for evolocumab and alirocumab versus simvastatin, pravastatin and rosuvastatin.

Conclusion

Our results demonstrated that 22.7% of all ICSRs reporting alirocumab or evolocumab as suspect drugs described the occurrence of neuropsychiatric ADRs. The ROR showed that evolocumab and alirocumab had a higher reporting probability of neurological ADRs compared with statins. Further data from real-life contexts are needed.

Electronic supplementary material

The online version of this article (10.1007/s40264-020-01021-3) contains supplementary material, which is available to authorized users.

An early neuroprotective effect of atorvastatin against subarachnoid hemorrhage

Atorvastatin has been shown to reduce early brain edema and neuronal death after subarachnoid hemorrhage, but its mechanism is not clear. In this study, rat models of subarachnoid hemorrhage were established by autologous blood injection in the cisterna magna. Rat models were intragastrically administered 20 mg/kg atorvastatin 24 hours before subarachnoid hemorrhage, 12 and 36 hours after subarachnoid hemorrhage. Compared with the controls, atorvastatin treatment demonstrated that at 72 hours after subarachnoid hemorrhage, neurological function had clearly improved; brain edema was remarkably relieved; cell apoptosis was markedly reduced in the cerebral cortex of rats; the number of autophagy-related protein Beclin-1-positive cells and the expression levels of Beclin-1 and LC3 were increased compared with subarachnoid hemorrhage only. The ultrastructural damage of neurons in the temporal lobe was also noticeably alleviated. The similarities between the effects of atorvastatin and rapamycin were seen in all the measured outcomes of subarachnoid hemorrhage. However, these were contrary to the results of 3-methyladenine injection, which inhibits the signaling pathway of autophagy. These findings indicate that atorvastatin plays an early neuroprotective role in subarachnoid hemorrhage by activating autophagy. The experimental protocol was approved by the Animal Ethics Committee of Anhui Medical University, China (904 Hospital of Joint Logistic Support Force of PLA; approval No. YXLL-2017-09) on February 22, 2017.

Atorvastatin upregulates apolipoprotein M expression via attenuating LXRα expression in hyperlipidemic apoE-deficient mice

Apolipoprotein M (apoM) is a recently identified human apolipoprotein that is associated with the formation of high-density lipoprotein (HDL). Studies have demonstrated that statins may affect the expression of apoM; however, the regulatory effects of statins on apoM are controversial. Furthermore, the underlying mechanisms by which statins regulate apoM remain unclear. In the present study, in vivo and in vitro models were used to investigate whether the anti-atherosclerotic effects of statins are associated with its apoM-regulating effects and the underlying mechanism. Hyperlipidemia was induced by in apolipoprotein E-deficient mice by providing a high-fat diet. Atorvastatin was administered to hyperlipidemic mice and HepG2 cells to investigate its effect on apoM expression. The liver X receptor α (LXRα) agonist T0901317 was also administered together with atorvastatin to hyperlipidemic mice and HepG2 cells. The results revealed that atorvastatin increased apoM expression, which was accompanied with decreased expression of LXRα in the liver of hyperlipidemic apolipoprotein E-deficient mice and HepG2 cells. Additionally, apoM upregulation was inhibited following treatment with T0901317. In summary, atorvastatin exhibited anti-atherosclerotic effects by upregulating apoM expression in hyperlipidemic mice, which may be mediated by the inhibition of LXRα.

Associations Between PFA-Measured Aspirin Resistance, Platelet Count, Renal Function, and Angiotensin Receptor Blockers

Aspirin resistance is used to describe patients who are undergoing aspirin therapy but fail for the inhibition of thromboxane biosynthesis in platelets. Although the true mechanism is unclear, drug–drug interaction remains a possible factor. The study aimed to determine whether there was association between aspirin resistance and the concomitant cardiovascular medication. Using the Platelet Function Analyzer-100 system, aspirin resistance was evaluated in aspirin-treated patients from the outpatient department. The associations between aspirin resistance and their concomitant common cardiovascular medication were analyzed. Aspirin resistance was prevalent in 147 (17.7%) of 831 patients. Concomitant angiotensin receptor blocker (ARB) treatment and low platelet count were associated with aspirin response (P = .04, .02, respectively). Multivariate logistic regression analysis results showed an association between aspirin response and ARB therapy (adjusted odds ratio [OR] 1.48; 95% confidence interval, CI: 1.08-2.18). And the association was blunted when platelet count was considered (adjusted OR 1.43, 95% CI: 0.92-2.23). In ARB-treated patients, increased creatinine and decreased hematocrit laboratory data increased the risk of aspirin resistance (P = .02, .04, respectively), and the effect of platelet count on aspirin resistance was diminished by ARB therapy. Concomitant ARB treatment in aspirin-treated patients decreased the risk of aspirin resistance, and the effect was dependent on low platelet count. In ARB-treated patients, increased creatinine and decreased hematocrit data increased the risk of aspirin resistance. In addition, the effect of platelet count on aspirin resistance was diminished by ARB treatment.

Protective effects of atorvastatin on cerebral vessel autoregulation in an experimental rabbit model of subarachnoid hemorrhage

The aim of the present study was to assess the therapeutic effects of atorvastatin on cerebral vessel autoregulation and to explore the underlying mechanisms in a rabbit model of subarachnoid hemorrhage (SAH). A total of 48 healthy male New Zealand rabbits (weight, 2–2.5 kg) were randomly allocated into SAH, Sham or SAH + atorvastatin groups (n=16/group). The Sham group received 20 mg/kg/d saline solution, whereas 20 mg/kg/d atorvastatin was administered to rabbits in the SAH + atorvastatin group following SAH induction. Changes in diameter, perimeter and basilar artery (BA) area were assessed and expression levels of the vasoactive molecules endothelin-1 (ET-1), von Willebrand factor (vWF) and thrombomodulin (TM) were measured. Neuronal apoptosis was analyzed 72 h following SAH by terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling (TUNEL) staining. The mortality rate in the SAH group was 18.75, 25% in the SAH + atorvastatin treated group and 0% in the Sham group (n=16/group). The neurological score in the SAH + atorvastatin group was 1.75±0.68, which was significantly higher compared with the Sham group (0.38±0.49; P<0.05). The BA area in the SAH + atorvastatin group (89.6±9.11) was significantly lower compared with the SAH group (115.4±11.0; P<0.01). The present study demonstrated that SAH induction resulted in a significant increase in the diameter, perimeter and cross-sectional area of the BA in the SAH + atorvastatin group. Administration of atorvastatin may significantly downregulate the expression levels of ET-1, vWF and TM (all P<0.01) vs. sham and SAH groups. TUNEL staining demonstrated that neuronal apoptosis was remarkably reduced in the hippocampus of SAH rabbits following treatment with atorvastatin (P<0.05). Atorvastatin treatment may alleviate cerebral vasospasm and mediate structural and functional remodeling of vascular endothelial cells, in addition to promoting anti-apoptotic signaling. These results provided supporting evidence for the use of atorvastatin as an effective and well-tolerated treatment for SAH in various clinical settings and may protect the autoregulation of cerebral vessels.

PFA-100-measured aspirin resistance is the predominant risk factor for hospitalized cardiovascular events in aspirin-treated patients: A 5-year cohort study

WHAT IS KNOWN AND OBJECTIVE

Aspirin therapy is the clinical gold standard for the prevention of cardiovascular events. However, cardiovascular events still develop in some patients undergoing aspirin therapy. Many laboratory methods exist for measuring aspirin resistance. Using the platelet Function Analyzer (PFA)-100 system, we aimed to determine the effect of aspirin resistance on hospitalized cardiovascular events (hCVE) in a 5-year follow-up cohort. We also sought to determine the impact of aspirin resistance on the relationship between common cardiovascular risk factors and cardiovascular hospitalization.

METHOD

Aspirin resistance was evaluated in aspirin-treated patients from the outpatient department. A total of 465 patients during a 5-year follow-up period were included in this study. The primary endpoint of the study was hospitalization for any acute cardiovascular event. The prevalence and associated risk factors of acute cardiovascular events were evaluated.

RESULTS AND DISCUSSION

Aspirin resistance was prevalent in 91 (20.0%) of 465 patients. Prior hospitalization history of cardiovascular events was highly associated with aspirin resistance (P = .001). At the 5-year follow-up, cardiovascular events were found to have developed in 11 patients (8 stroke and 3 myocardial infarction) who exhibited aspirin resistance (12.1%) and in 9 (4 stroke and 5 myocardial infarction) patients who did not exhibit aspirin resistance (2.4%) (P < .001). At the 5-year follow-up, multivariate logistic regression analysis results showed a strong association between aspirin resistance and cardiovascular events (adjusted odds ratio 4.28; 95% CI: 1.64-11.20; P = .03).

WHAT IS NEW AND CONCLUSION

PFA-100 measurements of aspirin resistance correlate with hCVE, as evidenced by both the past medical history and the 5-year follow-up. The logistic regression analysis results showed that aspirin resistance plays a larger role in hospitalized cardiovascular disease than do other cardiovascular risk factors.

Effects of atorvastatin on ADP-, arachidonic acid-, collagen-, and epinephrine-induced platelet aggregation

Objective

Atorvastatin reduces the incidence of cardiovascular events. However, the effects of atorvastatin on platelet aggregation are unknown.

Methods

Blood samples were obtained from 126 healthy volunteers. Prepared isolated platelet suspensions were adjusted with saline to three different concentrations of 100 × 10⁹, 300 × 10⁹, and 600 × 10⁹ platelets/L. Platelet samples were incubated with atorvastatin (10⁻⁷mol/L, 10⁻⁶mol/L or 10⁻⁵mol/L), and stimulated with ADP (10 µmol/L), arachidonic acid (0.5 mmol/L), collagen (2 µg/mL), and epinephrine (1 mg/mL). The maximal amplitude of aggregation and the curve slope were measured by electric impedance aggregometry.

Results

Atorvastatin inhibited platelet aggregation at moderate (300 × 10⁹/L) and high (600 × 10⁹/L) concentrations. However, an inhibitory effect of atorvastatin at low concentrations (100 × 10⁹/L) was not observed.

Conclusions

The study shows that atorvastatin inhibits platelet aggregation in vitro, and this inhibitory effect is related to platelet concentrations.

Atorvastatin ameliorates early brain injury after subarachnoid hemorrhage via inhibition of AQP4 expression in rabbits

The therapeutic effects of atorvastatin on early brain injury (EBI), cerebral edema and its association with aquaporin 4 (AQP4) were studied in rabbits after subarachnoid hemorrhage (SAH) using western blot analysis and the dry-wet method. Seventy-two healthy male New Zealand rabbits weighing between 2.5 and 3.2 kg were randomly divided into three groups: the SAH group (n=24), sham-operated group (n=24) and the SAH + atorvastatin group (n=24). A double SAH model was employed. The sham-operated group were injected with the same dose of saline solution, the SAH + atorvastatin group received atorvastatin 20 mg/kg/day after SAH. All rabbit brain samples were taken at 72 h after the SAH model was established successfully. Brain edema was detected using the dry-wet method after experimental SAH was induced; AQP4 and caspase-3 expression was measured by western blot analysis, and neuronal apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) staining at 72 h after SAH. The results indicated that brain edema and injury appeared soon after SAH, while brain edema and EBI were ameliorated and increased behavior scores were noted after prophylactic use of atorvastatin. Compared with the SAH group, the level of AQP4 and the cerebral content of water was significantly decreased (P<0.01) by atorvastatin, and TUNEL staining and studying the expression of caspase-3 showed that the apoptosis of neurons was reduced markedly both in the hippocampus and brain cortex by atorvastatin. The results suggest that atorvastatin ameliorated brain edema and EBI after SAH, which was related to its inhibition of AQP4 expression. Our findings provide evidence that atorvastatin is an effective and well-tolerated approach for treating SAH in various clinical settings.

Effect of coenzyme Q10 and Ardisia japonica Blume on plasma and liver lipids, platelet aggregation, and erythrocyte Na efflux channels in simvastatin-treated guinea pigs

Forty guinea pigs were divided into four groups and fed 0.04% cholesterol based control diet, plus 0.05% simvastatin, and statin plus 0.1% CoQ10 or 10% Ardisia Japonica Blume (AJB) leave powder for 4 weeks. Plasma total cholesterol levels decreased significantly in all groups fed the statin-containing diet compared with that in guinea pigs fed the control diet (P < 0.01). Plasma and liver triglycerides decreased significantly in the statin plus CoQ10 group compared with those in the control (both P < 0.05). Maximum platelet aggregation was significantly higher in the statin plus CoQ10 group than that in the other groups (P < 0.05). Na-K ATPase activity increased in the statin group and decreased in the statin plus CoQ10 group (P < 0.01). Na-K co-transport and Na passive transport decreased significantly in the control group compared with those in the other groups (both P < 0.05). Intracellular Na was highest in the statin group and lowest in the statin plus CoQ10 group and was correlated with Na-K ATPase activity. Thiobarbituric acid reactive substance production in platelet-rich plasma and liver tended to decrease in the statin plus CoQ10 group compared with those in the other groups. Plasma glutamic-pyruvic transaminase and glutamic-oxaloacetic transaminase increased significantly in the statin group compared with those in the control (P < 0.05). These result suggest that antioxidant rich AJB did not have positive effects on cardiovascular disease parameters. The statin plus CoQ10 seemed to decrease cholesterol more efficiently than that of statin alone.

Pravastatin and simvastatin improves acetylsalicylic acid-mediated in vitro blood platelet inhibition

BACKGROUND

Insight into the pathophysiology of atherothrombosis indicates that an integrated risk factor approach, focusing particularly on the management of dyslipidaemia (with statins) and thrombosis (with ASA), may constitute an optimal therapeutic approach. We investigated whether pravastatin, simvastatin and atorvastatin may directly modulate under in vitro conditions the reactivity of blood platelets originating from healthy volunteers. In addition, we analysed the influence of statins on the platelet sensitivity to ASA under such conditions.

MATERIALS AND METHODS

We monitored collagen- or ADP-induced platelet aggregation, CD36, PAC-1 and CD62 expression on platelet surface and thromboxane generation after incubation with pravastatin, simvastatin, atorvastatin and/or ASA.

RESULTS

The incubation of whole blood with simvastatin and pravastatin significantly decreased CD36 expression. In the presence of 50 μM ASA, simvastatin and pravastatin significantly reduced the PAC-1 expression (30% reduction for simvastatin, P < 0·01, and 15% reduction for pravastatin, P < 0·01), platelet aggregation (20% reduction for both statins, P < 0·01) and thromboxane generation (35% reduction for simvastatin, P < 0·001, and 30% reduction for pravastatin, P < 0·001) compared to ASA alone. Atorvastatin changed neither baseline platelet aggregation nor ASA-mediated platelet inhibition.

CONCLUSIONS

Our results suggested that statins may directly interact with platelet membranes or may modulate a signalling pathway in platelets (the pleiotropic effects of statins). It is possible that the statin effect on CD36 and ASA-mediated protein acetylation can be reached by the modulation of a distribution or a function of membrane-associated proteins. Further studies are certainly needed to better elucidate the mechanism(s) underlying the statins' effects on platelet sensitivity to ASA.