Current and novel antiplatelet therapies for the treatment of cardiovascular diseases

Over the last decades, antiplatelet agents, mainly aspirin and P2Y12 receptor antagonists, have significantly reduced morbidity and mortality associated with arterial thrombosis. Their pharmacological characteristics, including pharmacokinetic/pharmacodynamics profiles, have been extensively studied, and a significant number of clinical trials assessing their efficacy and safety in various clinical settings have established antithrombotic efficacy. Notwithstanding, antiplatelet agents carry an inherent risk of bleeding. Given that bleeding is associated with adverse cardiovascular outcomes and mortality, there is an unmet clinical need to develop novel antiplatelet therapies that inhibit thrombosis while maintaining hemostasis. In this review, we present the currently available antiplatelet agents, with a particular focus on their targets, pharmacological characteristics, and patterns of use. We will further discuss the novel antiplatelet therapies in the pipeline, with the goal of improved clinical outcomes among patients with atherothrombotic diseases

Impact of aspirin and clopidogrel interruption on platelet function in patients undergoing major vascular surgery.

AIMS: To investigate functional platelet recovery after preoperative withdrawal of aspirin and clopidogrel and platelet function 5 days after treatment resumption. METHODS/RESULTS: We conducted an observational study, which prospectively included consecutive patients taking aspirin, taking clopidogrel, and untreated controls (15 patients in each group). The antiplatelet drugs were withdrawn five days before surgery (baseline) and were reintroduced two days after surgery. Platelet function was evaluated by optical aggregation in the presence of collagen, arachidonic acid (aspirin) and ADP (clopidogrel) and by VASP assay (clopidogrel). Platelet-leukocyte complex (PLC) level was quantified at each time-point. At baseline, platelet function was efficiently inhibited by aspirin and had recovered fully in most patients 5 days after drug withdrawal. PLC levels five days after aspirin reintroduction were similar to baseline (+4±10%; p = 0.16), in line with an effective platelet inhibition. Chronic clopidogrel treatment was associated with variable platelet inhibition and its withdrawal led to variable functional recovery. PLC levels were significantly increased five days after clopidogrel reintroduction (+10±15%; p = 0.02), compared to baseline. CONCLUSIONS: Aspirin withdrawal 5 days before high-bleeding-risk procedures was associated with functional platelet recovery, and its reintroduction two days after surgery restored antiplaletet efficacy five days later. This was not the case of clopidogrel, and further work is therefore needed to define its optimal perioperative management

Soluble endoglin reduces thrombus formation and platelet aggregation via interaction with αIIbβ3 integrin

14 p.-6 fig.Background: The circulating form of human endoglin (sEng) is a cleavage product of membrane-bound endoglin present on endothelial cells. Because sEng encompasses an RGD motif involved in integrin binding, we hypothesized that sEng would be able to bind integrin αIIbβ3, thereby compromising platelet binding to fibrinogen and thrombus stability.Methods: In vitro human platelet aggregation, thrombus retraction, and secretion-competition assays were performed in the presence of sEng. Surface plasmon resonance (SPR) binding and computational (docking) analyses were carried out to evaluate protein-protein interactions. A transgenic mouse overexpressing human sEng (hsEng+) was used to measure bleeding/rebleeding, prothrombin time (PT), blood stream, and embolus formation after FeCl3-induced injury of the carotid artery.Results: Under flow conditions, supplementation of human whole blood with sEng led to a smaller thrombus size. sEng inhibited platelet aggregation and thrombus retraction, interfering with fibrinogen binding, but did not affect platelet activation. SPR binding studies demonstrated that the specific interaction between αIIbβ3 and sEng and molecular modeling showed a good fitting between αIIbβ3 and sEng structures involving the endoglin RGD motif, suggesting the possible formation of a highly stable αIIbβ3/sEng. hsEng+ mice showed increased bleeding time and number of rebleedings compared to wild-type mice. No differences in PT were denoted between genotypes. After FeCl3 injury, the number of released emboli in hsEng+ mice was higher and the occlusion was slower compared to controls.Conclusions: Our results demonstrate that sEng interferes with thrombus formation and stabilization, likely via its binding to platelet αIIbβ3, suggesting its involvement in primary hemostasis control.Promex Stiftung für die Forschung Foundation Consejo Superior de Investigaciones Científicas; Grant/Award Number: 201920E022 Spanish Ministry of Science, Innovation & Universities; Grant/Award Number: RTI2018-102242-B-I00 Comunidad de Madrid; Grant/Award Number: S2022/BMD-7278Peer reviewe

Etude de la signalisation au cours de la rétraction du caillot (application à l'étude des anomalies de l'hémostase primaire dans le syndrome de Lowe)

L hémostase primaire est un processus permettant la formation d un clou plaquettaire qui sera stabilisé par un réseau de fibrine. Ce caillot est également consolidé grâce à des phases tardives de l hémostase primaire résultant des fonctions plaquettaires ; il s agit principalement de la rétraction qui diminue la taille du caillot afin de le stabiliser. Cette phase est déclenchée par une signalisation outside-in , consécutive à l activation de l intégrine aIIbb3 et à l agrégation plaquettaire, et est dépendante d une réorganisation du cytosquelette. Le premier objectif de ce travail a été d étudier la signalisation impliquée dans la rétraction, et en particulier l implication des protéines ROCK, MLCK, Rac-1 et de l actine dans l activité de la chaine légère de la myosine (MLC) . MLC est en effet une protéine clé de la réorganisation du cytosquelette. Nous avons mis en évidence une phosphorylation biphasique de MLC dont le deuxième pic, corrélé à la rétraction, est dépendant de Rac1 et de la polymérisation de l actine. Cette étude a été appliquée à une pathologie, le syndrome de Lowe. Il s agit d une maladie génétique rare, également appelée OCRL (Oculo cérébro rénal de Lowe) en référence aux organes majoritairement touchés. Suite à l observation d événements hémorragiques per et postopératoires suggérant une instabilité du caillot et l observation dans une étude précédente d un temps d occlusion allongé au PFA100®, nous avons mis en place une étude sur 15 patients et 15 témoins pour lesquels nous avons étudié les différentes phases de l hémostase primaire. Outre une anomalie et un retard de maturation des mégacaryocytes, nous avons mis en évidence pour la première fois chez ces patients un défaut de la voie outside-in responsable d une anomalie de l étalement plaquettaire et de la rétraction du caillot. Ce défaut de rétraction, dû à un défaut d activation de MLC, pourrait être en partie responsable des événements hémorragiques observés chez ces patients.Primary hemostasis is a mechanism allowing platelet clot formation that is thereafter stabilized by a fibrin network. Fibrin clot is also consolidated following post occupancy events, mainly clot retraction that decrease clot size and thus strengthen it. This phase is triggered by outside-in signaling. It is consecutive to aIIbb3 integrin activation and platelet aggregation, dependent on cytoskeleton organization. Our first objective was to investigate signaling events underlying retraction, and particularly the involvement of ROCK, MLCK, Rac-1, and actin in MLC (Myosin Light Chain) phosphorylation. Indeed, MLC, involved in cytoskeleton rearrangement, is a key protein of this mechanism. We described a MLC biphasic phosphorylation profile, which second peak was dependent of Rac1 and actin polymerization. In a second part, we studied clot retraction signaling in patients with the Lowe syndrome. It is a rare genetic disease, caused by absence of OCRL (oculo cerebro renal of Lowe) protein in reference to the majority of affected organs. The rationale of this study was a previous observation of hemorrhagic events during and after surgeries, suggesting clot instability. A thrombopathy was suggested by a closure time lengthening in the PFA-100 system. The study enrolled 15 patients and 15 controls. Besides a defect of megakaryocyte maturation, we described a defect of outside-in signaling responsible for spreading and clot retraction abnormality. This retraction defect, caused by a MLC activity defect, could be partly responsible for hemorrhagic events reported in these patients.PARIS5-Bibliotheque electronique (751069902) / SudocPARIS-BIUM-Bib. électronique (751069903) / SudocSudocFranceF

Association des plaquettes aux leucocytes dans la thrombopénie induite par l'héparine

La thrombopénie induite par l'héparine (TIH), une complication majeure de l'héparinothérapie caractérisée par une thrombopénie associée fréquemment à des thromboses, est expliquée par une activation immunologique des plaquettes par des anticorps anti Héparine-Facteur Plaquettaire 4 (anti H-FP4). Nous avons montré que les plasmas TIH en présence d'héparine induisent une augmentation des associations leucocytes-plaquettes dans le sang de donneurs sains, corrélée à la quantité d'immunoglobulines G anti H-FP4 contenue dans le plasma des patients. Ces associations leuco-plaquettaires s'effectue par l'intermédiaire de la P-sélectine exprimée à la surface des plaquettes activées, et semblent contribuer à l'activation des leucocytes (granulocytes et monocytes) par les plasmas TIH. La concentration de la myeloperoxidase, un marqueur de dégranulation des leucocytes, est plus élevée dans les plasmas TIH par rapport aux plasmas contrôles, suggérant une dégranulation des leucocytes lors de la TIH.Heparin-Induced Thrombocytopenia (HIT), a severe complication of heparin therapy, results of platelet activation, via the receptor for the Fc domain of immunoglobulin G (FcgRIIa), by heparin-dependent-antibodies, commonly directed against the heparin-platelet factor 4 (H-PF4) antigenic complex. Using whole blood from healthy donors, we showed that HIT plasma induced the formation of platelet-leukocyte aggregates in a heparin-dependent manner. The formation of these aggregates was mediated by P-selectin present on the activated platelet surface, and correlated with the level of anti-H-PF4 immunoglobulin G contained in the HIT plasma. Leukocyte activation was induced by HIT plasma in a heparin-dependent manner. In whole blood, platelet association with monocytes and PMN, and the activation of these leukocytes by HIT plasma were interrelated. HIT plasma contained higher myeloperoxidase concentrations than control plasma, suggesting leukocyte degranulation during HIT.PARIS-BIUP (751062107) / SudocSudocFranceF

Implication de la protéine Gas6 et de ses récepteurs dans l'activation des plaquettes humaines

PARIS-BIUP (751062107) / SudocSudocFranceF

P2Y Inhibition beyond Thrombosis Effects on Inflammation

International audienceThe P2Y receptor is a key player in platelet activation and a major target for antithrombotic drugs. The beneficial effects of P2Y receptor antagonists might, however, not be restricted to the primary and secondary prevention of arterial thrombosis. Indeed, it has been established that platelet activation also has an essential role in inflammation. Additionally, nonplatelet P2Y receptors present in immune cells and vascular smooth muscle cells might be effective players in the inflammatory response. This review will investigate the biological and clinical impact of P2Y receptor inhibition beyond its platelet-driven antithrombotic effects, focusing on its anti-inflammatory role. We will discuss the potential molecular and cellular mechanisms of P2Y-mediated inflammation, including cytokine release, platelet-leukocyte interactions and neutrophil extracellular trap formation. Then we will summarize the current evidence on the beneficial effects of P2Y antagonists during various clinical inflammatory diseases, especially during sepsis, acute lung injury, asthma, atherosclerosis, and cancer