Antiplatelet and antithrombin strategies in acute coronary syndrome: state-of-the-art review

Mechanism and Potential Target of Blood-Activating Chinese Botanical Drugs Combined With Anti-Platelet Drugs: Prevention and Treatment of Atherosclerotic Cardiovascular Diseases

Atherosclerotic cardiovascular diseases (ASCVDs) are the most important diseases that endanger people’s health, leading to high morbidity and mortality worldwide. In addition, various thrombotic events secondary to cardiovascular and cerebrovascular diseases need must be considered seriously. Therefore, the development of novel anti-platelet drugs with high efficiency, and fewer adverse effects has become a research focus for preventing of cardiovascular diseases (CVDs). Blood-activation and stasis-removal from circulation have been widely considered as principles for treating syndromes related to CVDs. Blood-activating Chinese (BAC botanical drugs, as members of traditional Chinese medicine (TCM), have shown to improve hemodynamics and hemorheology, and inhibit thrombosis and atherosclerosis. Modern medical research has identified that a combination of BAC botanical drugs and anti-platelet drugs, such as aspirin or clopidogrel, not only enhances the anti-platelet effects, but also reduces the risk of bleeding and protects the vascular endothelium. The anti-platelet mechanism of Blood-activating Chinese (BAC) botanical drugs and their compounds is not clear; therefore, their potential targets need to be explored. With the continuous development of bioinformatics and “omics” technology, some unconventional applications of BAC botanical drugs have been discovered. In this review, we will focus on the related targets and signaling pathways of anti-atherosclerotic treatments involving a combination of BAC botanical drugs and anti-platelet drugs reported in recent years.

Polymorphisms of genes related to phase-I metabolic enzymes affecting the clinical efficacy and safety of clopidogrel treatment

Introduction: Clopidogrel is an antiplatelet medication described as a prodrug, which cannot exert the antiplatelet effect until being biotransformed to the active metabolite. It is commonly used to reduce the risk of blood coagulation in patients diagnosed with acute coronary syndrome, or ischemic stroke.Area covered: We reviewed published articles in PubMed and Google Scholar that focused on the mutations of CYP2C19, CYP3A4, CYP2C9, CYP2B6, and CYP1A2 genes related to clopidogrel clinical efficacy and safety.Expert opinion: Based on current pharmacogenetic studies, patients carrying CYP2C19*2, CYP2C19*3, CYP2C9*3, and CYP2B6*5 alleles may not respond to clopidogrel due to poor platelet inhibition efficacy revealed among them. In contrast, carriers of CYP2C19*17, CYP3A4*1G, and CYP1A2*1C alleles showed a more significant antiplatelet effect in clopidogrel users and expected to have a protective role as a genetic factor against cardiovascular events. Genotyping for either CYP2C19, CYP3A4, CYP2C9, CYP2B6, or CYP1A2 variants is not recommended when considering clopidogrel treatment for patients, as some trials showed specific non-genetic factors (e.g. age and diabetes) that could affect clopidogrel responsiveness. Instead, platelets inhibition tests could be used as predictors of the clinical efficacy of clopidogrel treatment. Other P2Y12 receptor inhibitors should be considered as alternative medications.

Formononetin may protect aged hearts from ischemia/reperfusion damage by enhancing autophagic degradation

Myocardial infarction is a leading cause of mortality worldwide, and timely blood/oxygen reperfusion may substantially improve the outcome of infarction. However, ischemia/reperfusion (I/R) may cause severe side effects through excess reactive oxygen species generation. To develop novel methods to relieve I/R induced cell damage, the present study used a component of traditional Chinese medicine. In the present study, isolated heart tissue from aged mice and H9C2 cells with chemically‑induced aging were used as experimental subjects, and it was demonstrated that formononetin was able to alleviate I/R‑induced cell or tissue apoptosis. By applying formononetin to I/R‑damaged tissue or cells, it was demonstrated that formononetin was able to enhance autophagy and thus alleviate I/R‑induced cell damage. Furthermore, it was observed that I/R was able to inhibit lysosomal degradation processes in aged tissues or cells by impairing the lysosome acidification level, and formononetin was able to reverse this process via the re‑acidification of lysosomes. In conclusion, the present study demonstrated that formononetin was able to alleviate I/R‑induced cellular apoptosis in aged cells by facilitating autophagy.

Effect of PEAR1 Genetic Variants on 1-Year Outcomes in Chinese Patients with Acute Myocardial Infarction After Percutaneous Coronary Intervention

AIMS

Platelet endothelial aggregation receptor-1 (PEAR1) is a platelet transmembrane protein that plays an important role on platelet aggregation. The aim of this study was to investigate whether PEAR1 genetic variations are associated with 1-year outcomes in Chinese patients with acute myocardial infarction after percutaneous coronary intervention.

METHODS

A total of 647 consecutive Chinese patients with acute myocardial infarction that underwent percutaneous coronary intervention and that were exposed to standard dual antiplatelet therapy with aspirin and clopidogrel were enrolled in this study. Six single nucleotide polymorphisms of PEAR1 were detected using the ligase detection reaction method. The follow-up period was 12 months.

RESULTS

Overall, 66 (10.2%) adverse ischemic events occurred. Multivariate Cox regression analysis showed that carriage of the PEAR1 rs56260937 minor allele was an independent predictor of revascularization events (OR=2.15, 95% CI 1.12-4.15, p=0.022) after adjusting for confounding factors.

CONCLUSIONS

Genetic testing for PEAR1 variants can be helpful in predicting adverse ischemic events in Chinese patients with acute myocardial infarction after percutaneous coronary intervention.

Tirofiban as treatment for acute retinal artery occlusion following internal carotid artery flow diverter implantation

PURPOSE

To report a favorable outcome of branch retinal artery occlusion (BRAO) treated by means of early administration of tirofiban, a glycoprotein IIb-IIIa platelet receptor inhibitor.

METHODS

Case report.

RESULTS

A 65-year-old woman developed dramatic visual impairment in her left eye secondary to BRAO after left internal carotid artery endovascular reconstruction with flow diverter stent implant; visual acuity was hand motion. A dose of intravenous tirofiban was injected 10 minutes after symptoms onset. Fourteen hours after drug infusion, retinal fluorescein angiography revealed a well-perfused macula with a partial reperfusion of the inferior temporal branch of the central retinal artery; visual acuity was 20/20 in both eyes.

CONCLUSIONS

This case supports the effectiveness of tirofiban in secondary BRAO in neurosurgery and may open its usage to further research.

New Approaches to the Role of Thrombin in Acute Coronary Syndromes: Quo Vadis Bivalirudin, a Direct Thrombin Inhibitor?

The pathophysiology of acute coronary syndrome (ACS) involves platelet activation and thrombus formation after the rupture of atherosclerotic plaques. Thrombin is generated at the blood-plaque interface in association with cellular membranes on cells and platelets. Thrombin also amplifies the response to the tissue injury, coagulation and platelet response, so the treatment of ACS is based on the combined use of both antiplatelet (such as aspirin, clopidogrel, prasugrel and ticagrelor) and antithrombotic drugs (unfractionated heparin, enoxaparin, fondaparinux and bivalirudin). Bivalirudin competitively inhibits thrombin with high affinity, a predictable response from its linear pharmacokinetics and short action. However, a present remarkable controversy exists between the latest main Guidelines in Clinical Practice and the key trials evaluating the use of bivalirudin in ACS. The aim of this review is to update the development of bivalirudin, including pharmacological properties, obtained information from clinical trials evaluating efficacy and safety of bivalirudin in ACS; as well as the recommendations of clinical Guidelines.

A Central Role for Monocyte-Platelet Interactions in Heart Failure

Heart failure (HF) is an increasingly prevalent and costly multifactorial syndrome with high morbidity and mortality rates. The exact pathophysiological mechanisms leading to the development of HF are not completely understood. Several emerging paradigms implicate cardiometabolic risk factors, inflammation, endothelial dysfunction, myocardial fibrosis, and myocyte dysfunction as key factors in the gradual progression from a healthy state to HF. Inflammation is now a recognized factor in disease progression in HF and a therapeutic target. Furthermore, the monocyte-platelet interaction has been highlighted as an important pathophysiological link between inflammation, thrombosis, endothelial activation, and myocardial malfunction. The contribution of monocytes and platelets to acute cardiovascular injury and acute HF is well established. However, their role and interaction in the pathogenesis of chronic HF are not well understood. In particular, the cross talk between monocytes and platelets in the peripheral circulation and in the vicinity of the vascular wall in the form of monocyte-platelet complexes (MPCs) may be a crucial element, which influences the pathophysiology and progression of chronic heart disease and HF. In this review, we discuss the role of monocytes and platelets as key mediators of cardiovascular inflammation in HF, the mechanisms of cell activation, and the importance of monocyte-platelet interaction and complexes in HF pathogenesis. Finally, we summarize recent information on pharmacological inhibition of inflammation and studies of antithrombotic strategies in the setting of HF that can inform opportunities for future work. We discuss recent data on monocyte-platelet interactions and the potential benefits of therapy directed at MPCs, particularly in the setting of HF with preserved ejection fraction.

Relation between K469E gene polymorphism of ICAM-1 and recurrence of ACS and cardiovascular mortality

OBJECTIVE

To explore the relation between K469E gene polymorphism of intercellular adhesion molecular-1 (ICAM-1) and the recurrence of ACS and cardiovascular mortality.

METHODS

A total of 185 patients with ACS hospitalized in Department of Cardiology in our hospital from Sep 2007 to Sep 2008 were selected as objectives. Polymerase chain reaction was used to analyze K469E gene polymorphism of ICAM-1. According to the genotypes, they were divided into two groups: group with K allele (KK+KE) and group without K allele (EE). The two groups were followed up prospectively for five years and blood lipid, blood pressure, blood glucose, recurrence and death of ACS were collected when the patients left hospital. The relation between ICAM-1 gene polymorphism and the recurrence of ACS and cardiovascular mortality was analyzed by Logistic regression.

RESULTS

After long-term follow-up, it was found that ACS recurred on 71 cases (38.4%) and 10 cases died, among which 3 cases died of cardiovascular disease. The recurrence of ACS and cardiovascular mortality in group with K allele were remarkably higher than that in group without K allele (P<0.01). After multivariate Logistic regression adjusted ages, gender, weight indexes, TC, LDL-C, TG, smoking, drinking, family history of cardiovascular disease, history of hypertension and the severity of coronary artery disease, the risks of ACS recurrence and cardiovascular mortality in group with genotype KK+KE was 3.31 and 3.53 times of those in group with genotype EE respectively (P<0.01). When the independent variable of hypertension was introduced in regression analysis, the risks of ACS recurrence and cardiovascular mortality in group with K allele both decreased (P<0.05). When the independent variable of HDL-C was introduced, different genotypes of ICAM-1 weren't relevant with ACS recurrence and cardiovascular mortality (P>0.05).

CONCLUSIONS

K469E gene polymorphism of ICAM-1 was related to ACS recurrence and cardiovascular mortality, K allele probably an independent risky factor and hypertension and to which the level of HDL-C were closely related.

Roles of proteolysis in regulation of GPCR function

The enzymatic activity of peptidases must be tightly regulated to prevent uncontrolled hydrolysis of peptide bonds, which could have devastating effects on biological systems. Peptidases are often generated as inactive propeptidases, secreted with endogenous inhibitors, or they are compartmentalized. Propeptidases become active after proteolytic removal of N-terminal activation peptides by other peptidases. Some peptidases only become active towards substrates only at certain pHs, thus confining activity to specific compartments or conditions. This review discusses the different roles proteolysis plays in regulating GPCRs. At the cell-surface, certain GPCRs are regulated by the hydrolytic inactivation of bioactive peptides by membrane-anchored peptidases, which prevent signalling. Conversely, cell-surface peptidases can also generate bioactive peptides, which directly activate GPCRs. Alternatively, cell-surface peptidases activated by GPCRs, can generate bioactive peptides to cause transactivation of receptor tyrosine kinases, thereby promoting signalling. Certain peptidases can signal directly to cells, by cleaving GPCR to initiate intracellular signalling cascades. Intracellular peptidases also regulate GPCRs; lysosomal peptidases destroy GPCRs in lysosomes to permanently terminate signalling and mediate down-regulation; endosomal peptidases cleave internalized peptide agonists to regulate GPCR recycling, resensitization and signalling; and soluble intracellular peptidases also participate in GPCR function by regulating the ubiquitination state of GPCRs, thereby altering GPCR signalling and fate. Although the use of peptidase inhibitors has already brought success in the treatment of diseases such as hypertension, the discovery of new regulatory mechanisms involving proteolysis that control GPCRs may provide additional targets to modulate dysregulated GPCR signalling in disease.