Epigallocatechin gallate inhibits release of extracellular vesicles from platelets without inhibiting phosphatidylserine exposure

Cardioprotective effect of epigallocatechin gallate in myocardial ischemia/reperfusion injury and myocardial infarction: a meta-analysis in preclinical animal studies

This meta-analysis aims to determine the efficacy of Epigallocatechin gallate (EGCG) in the treatment of myocardial ischemia-reperfusion injury (MIRI) and summarize the mechanisms involved. Literature from six databases including Web of Science, PubMed, Embase, China National Knowledge Infrastructure (CNKI), Wan-Fang database, and VIP database (VIP) were systematically searched. All the analysis were conducted by R. Twenty-five eligible studies involving 443 animals were included in this meta-analysis. The results indicated that compared to controls, EGCG exerts a cardioprotective effect by reducing myocardial infarct size (SMD = -4.06; 95% CI: -5.17, -2.94; P < 0.01; I2 = 77%). The funnel plot revealed publication bias. Moreover, EGCG significantly improves cardiac function, serum myocardial injury enzyme, and oxidative stress levels in MIRI animal models. This meta-analysis demonstrates that EGCG exhibits therapeutic promise in animal models of MIRI. However, further validation is still needed in large animal models and large clinical studies.

The Platelet Aggregation Inhibition Activity of Polyphenols can be mediated by 67kda Laminin Receptor: A New Therapeutic Strategy For the Treatment of Venous Thromboembolism

BACKGROUND

Thrombotic disease is still a major killer. Aspirin, Ticagrelor, Clopidogrel, etc. are the most widely used conventional antiplatelet drugs. The significant number of patients who are resistant to this drug shows a poor outcome.

OBJECTIVE

Developing a new antiplatelet agent with a stable antiplatelet effect and minimal bleeding risk is required for a patient who is resistant to antiplatelet drugs.

METHOD

Protein-ligand docking was performed using Autodock Vina 1.1.2 to study the interaction of 67LR with different Polyphenols.

RESULT

Among the 18 polyphenols, thearubigin has the highest binding affinity towards 67LR and gallic acid shows the lowest binding affinity. Among the 18 molecules, the top 10 molecules from the highest to lowest binding affinity range from-10.6 (thearubigin) to -6.5 (Epigallocatechin).

CONCLUSION

Polyphenols may inhibit platelet aggregation through 67 LR and can be an alternative treatment for Thrombotic Disease. Moreover, it will be interesting to know whether polyphenols interfere with the same pathways as aspirin and clopidogrel. Effective polyphenols could help prototype the compound development of novel antiplatelet agents.

Hydroxyls on the B ring and gallic acyl are essential for catechins to restrain ADP-induced thrombosis

Platelet hyperactivation could lead to various cardiovascular and cerebrovascular diseases, while epidemiological analyses have found that long-term tea drinking could prevent and restrain cardiovascular diseases. Existing studies have shown that catechins, especially epigallocatechin gallate (EGCG), are the main functional factors of tea in alleviating thrombosis, which could inhibit arterial thrombosis and platelet aggregation induced by a variety of agonists. However, their structure-activity relationship and the underlying mechanisms are still unclear. Based on the above background, this study took six typical catechins as research objects, constructed platelet activation models with different inducers, and explored the inhibitory effects and potential mechanisms of catechins with different structures on platelet aggregation through flow cytometry, immunoblotting, cell spreading, and other experiments. It was found that ester catechins could inhibit platelet aggregation induced by adenosine diphosphate (ADP), while epigallocatechin (EGC) with three hydroxyls on the B ring in non-ester catechins was also able to effectively inhibit platelet aggregation. Our data suggested that gallic acyl on the C ring and three hydroxyls on the B ring were the main functional groups affecting the antithrombotic effect of catechins, and the effect of gallic acyl on platelets was significantly stronger than that of the hydroxyl.

Q94 is not a selective modulator of proteinase-activated receptor 1 (PAR1) in platelets

Thrombin is a potent platelet activator, acting through proteinase-activated receptors -1 and -4 (PAR1 and PAR4). Of these, PAR-1 is activated more rapidly and by lower thrombin concentrations. Consequently, PAR-1 has been extensively investigated as a target for anti-platelet drugs to prevent myocardial infarction. Q94 has been reported to act as an allosteric modulator of PAR1, potently and selectively inhibiting PAR1-Gαq coupling in multiple cell lines, but its effects on human platelet activation have not been previously studied. Platelet Ca²⁺ signaling, integrin α_IIbβ₃ activation and α-granule secretion were monitored following stimulation by a PAR1-activating peptide (PAR1-AP). Although Q94 inhibited these responses, its potency was low compared to other PAR1 antagonists. In addition, α_IIbβ₃ activation and α-granule secretion in response to other platelet activators were also inhibited with similar potency. Finally, in endothelial cells, Q94 did not inhibit PAR1-dependent Ca²⁺ signaling. Our data suggest that Q94 may have PAR1-independent off-target effects in platelets, precluding its use as a selective PAR1 allosteric modulator.

Virus-Induced Membrane Fusion in Neurodegenerative Disorders

A growing body of epidemiological and research data has associated neurotropic viruses with accelerated brain aging and increased risk of neurodegenerative disorders. Many viruses replicate optimally in senescent cells, as they offer a hospitable microenvironment with persistently elevated cytosolic calcium, abundant intracellular iron, and low interferon type I. As cell-cell fusion is a major driver of cellular senescence, many viruses have developed the ability to promote this phenotype by forming syncytia. Cell-cell fusion is associated with immunosuppression mediated by phosphatidylserine externalization that enable viruses to evade host defenses. In hosts, virus-induced immune dysfunction and premature cellular senescence may predispose to neurodegenerative disorders. This concept is supported by novel studies that found postinfectious cognitive dysfunction in several viral illnesses, including human immunodeficiency virus-1, herpes simplex virus-1, and SARS-CoV-2. Virus-induced pathological syncytia may provide a unified framework for conceptualizing neuronal cell cycle reentry, aneuploidy, somatic mosaicism, viral spreading of pathological Tau and elimination of viable synapses and neurons by neurotoxic astrocytes and microglia. In this narrative review, we take a closer look at cell-cell fusion and vesicular merger in the pathogenesis of neurodegenerative disorders. We present a "decentralized" information processing model that conceptualizes neurodegeneration as a systemic illness, triggered by cytoskeletal pathology. We also discuss strategies for reversing cell-cell fusion, including, TMEM16F inhibitors, calcium channel blockers, senolytics, and tubulin stabilizing agents. Finally, going beyond neurodegeneration, we examine the potential benefit of harnessing fusion as a therapeutic strategy in regenerative medicine.