Vascular protective effect of aspirin and rivaroxaban upon endothelial denudation of the mouse carotid artery.
ABSTRACT: While in recent trials the dual pathway inhibition with aspirin plus rivaroxaban has shown to be efficacious in patients with atherosclerotic cardiovascular disease, little is known about the effects of this combination treatment on thrombus formation and vascular remodelling upon vascular damage. The aim of this study was to examine the effects of aspirin and/or rivaroxaban on injury-induced murine arterial thrombus formation in vivo and in vitro, vessel-wall remodelling, and platelet-leukocyte aggregates. Temporary ligation of the carotid artery of C57BL/6 mice, fed a western type diet, led to endothelial denudation and sub-occlusive thrombus formation. At the site of ligation, the vessel wall stiffened and the intima-media thickened. Aspirin treatment antagonized vascular stiffening and rivaroxaban treatment led to a positive trend towards reduced stiffening. Local intima-media thickening was antagonized by both aspirin or rivaroxaban treatment. Platelet-leukocyte aggregates and the number of platelets per leukocyte were reduced in aspirin and/or rivaroxaban treatment groups. Furthermore, rivaroxaban restricted thrombus growth and height in vitro. In sum, this study shows vascular protective effects of aspirin and rivaroxaban, upon vascular injury of the mouse artery.
Project description:Dabigatran and rivaroxaban are novel oral anticoagulants that specifically inhibit thrombin and factor Xa, respectively. The aim of this study is to elucidate antithrombotic properties of these anticoagulant agents under arterial and venous shear conditions. Whole blood samples treated with dabigatran or rivaroxaban at 250, 500, and 1000 nM, with/without aspirin and AR-C66096, a P2Y12 antagonist, were perfused over a microchip coated with collagen and tissue thromboplastin at shear rates of 240 and 600 s(-1). Fibrin-rich platelet thrombus formation was quantified by monitoring flow pressure changes. Dabigatran at higher concentrations (500 and 1000 nM) potently inhibited thrombus formation at both shear rates, whereas 1000 nM of rivaroxaban delayed, but did not completely inhibit, thrombus formation. Dual antiplatelet agents weakly suppressed thrombus formation at both shear rates, but intensified the anticoagulant effects of dabigatran and rivaroxaban. The anticoagulant effects of dabigatran and rivaroxaban were also evaluated under static conditions using thrombin generation (TG) assay. In platelet-poor plasma, dabigatran at 250 and 500 nM efficiently prolonged the lag time (LT) and moderately reduce peak height (PH) of TG, whereas rivaroxaban at 250 nM efficiently prolonged LT and reduced PH of TG. In platelet-rich plasma, however, both anticoagulants efficiently delayed LT and reduced PH of TG. Our results suggest that dabigatran and rivaroxaban may exert distinct antithrombotic effects under flow conditions, particularly in combination with dual antiplatelet therapy.
Project description:<h4>Background</h4>Patients with chronic coronary artery disease (CAD) and/or peripheral artery disease (PAD) have increased risks for cardiovascular (CV)-related morbidity and mortality. In the Cardiovascular Outcomes for People Using Anticoagulation Strategies (COMPASS) clinical trial of such patients, rivaroxaban plus aspirin demonstrated a significant reduction in major adverse CV events (MACE), a composite of stroke, myocardial infarction, and CV death, and major adverse limb events (MALE), a composite of chronic and acute limb ischemia, and major amputation resulting from vascular events, versus aspirin alone.<h4>Objective</h4>To estimate the 1-year economic implications of preventing MACE and MALE with the use of rivaroxaban plus aspirin versus aspirin alone among patients with chronic CAD and/or PAD in a US commercial health plan.<h4>Method</h4>A cost-consequence model was developed to evaluate the economic impact of rivaroxaban plus aspirin in a hypothetical 1-million-member health plan. The model inputs were taken from the COMPASS study (ie, the efficacy and safety of rivaroxaban plus aspirin vs aspirin), Optum Integrated Database (ie, the prevalence of chronic CAD and/or PAD, incidence rates, and healthcare costs of MACE, MALE, and major bleeding), and the RED BOOK (ie, wholesale drug acquisition costs). The cost inputs were in 2019 US dollars. One-way sensitivity analyses and subgroup analyses were conducted.<h4>Results</h4>A 1-year treatment with rivaroxaban plus aspirin resulted in reductions of MACE and MALE, which balance the increased risk for bleeding versus aspirin alone and indicate a net health benefit for this drug regimen. These reductions were achieved at an incremental per-member per-month (PMPM) cost of $0.16, mainly because of rivaroxaban's acquisition cost. In patients with ?2 MACE or MALE risk factors, the incremental PMPM cost was $0.09, given the increased offset in rivaroxaban's acquisition cost by reduced rates of MACE or MALE.<h4>Conclusions</h4>In an era of emerging thrombocardiology, treatment with rivaroxaban plus aspirin offers an effective thrombotic risk management strategy for healthcare stakeholders in the management of chronic CAD and/or PAD. The contribution of rivaroxaban would be greater in patients with ?2 risk factors for MACE or MALE.
Project description:Age is the most significant risk factor for atherosclerosis; however, the link between age and atherosclerosis is poorly understood. During both aging and atherosclerosis progression, the blood vessel wall stiffens owing to alterations in the extracellular matrix. Using in vitro and ex vivo models of vessel wall stiffness and aging, we show that stiffening of extracellular matrix within the intima promotes endothelial cell permeability--a hallmark of atherogenesis. When cultured on hydrogels fabricated to match the elasticity of young and aging intima, endothelial monolayers exhibit increased permeability and disrupted cell-cell junctions on stiffer matrices. In parallel experiments, we showed a corresponding increase in cell-cell junction width with age in ex vivo aortas from young (10 weeks) and old (21 to 25 months) healthy mice. To investigate the mechanism by which matrix stiffening alters monolayer integrity, we found that cell contractility increases with increased matrix stiffness, mechanically destabilizing cell-cell junctions. This increase in endothelial permeability results in increased leukocyte extravasation, which is a critical step in atherosclerotic plaque formation. Mild inhibition of Rho-dependent cell contractility using Y-27632, an inhibitor of Rho-associated kinase, or small interfering RNA restored monolayer integrity in vitro and in vivo. Our results suggest that extracellular matrix stiffening alone, which occurs during aging, can lead to endothelial monolayer disruption and atherosclerosis pathogenesis. Because previous therapeutics designed to decrease vascular stiffness have been met with limited success, our findings could be the basis for the design of therapeutics that target the Rho-dependent cellular contractile response to matrix stiffening, rather than stiffness itself, to more effectively prevent atherosclerosis progression.
Project description:In antiphospholipid syndrome (APS), antiphospholipid antibodies (aPL) binding to β2 glycoprotein I (β2GPI) induce endothelial cell-leukocyte adhesion and thrombus formation via unknown mechanisms. Here we show that in mice both of these processes are caused by the inhibition of eNOS. In studies of cultured human, bovine, and mouse endothelial cells, the promotion of monocyte adhesion by aPL entailed decreased bioavailable NO, and aPL fully antagonized eNOS activation by diverse agonists. Similarly, NO-dependent, acetylcholine-induced increases in carotid vascular conductance were impaired in aPL-treated mice. The inhibition of eNOS was caused by antibody recognition of domain I of β2GPI and β2GPI dimerization, and it was due to attenuated eNOS S1179 phosphorylation mediated by protein phosphatase 2A (PP2A). Furthermore, LDL receptor family member antagonism with receptor-associated protein (RAP) prevented aPL inhibition of eNOS in cell culture, and ApoER2-/- mice were protected from aPL inhibition of eNOS in vivo. Moreover, both aPL-induced increases in leukocyte-endothelial cell adhesion and thrombus formation were absent in eNOS-/- and in ApoER2-/- mice. Thus, aPL-induced leukocyte-endothelial cell adhesion and thrombosis are caused by eNOS antagonism, which is due to impaired S1179 phosphorylation mediated by β2GPI, apoER2, and PP2A. Our results suggest that novel therapies for APS can now be developed targeting these mechanisms.
Project description:Very low-dose (VLD) factor Xa (FXa) inhibition, in combination with acetylsalicylic acid (ASA) and clopidogrel, is associated with improved outcomes in patients with acute coronary syndrome (ACS) with a tolerable bleeding risk profile. To date, there are no data documenting platelet inhibition and the anticoagulatory effects of VLD FXa inhibition on top of guideline-adherent dual-antiplatelet therapy (DAPT) in patients with ACS. Patients with non-ST-elevation myocardial infarction (NSTEMI) receiving oral DAPT (ASA + clopidogrel, n = 20; or ASA + ticagrelor, n = 20) were prospectively enrolled in a nonrandomized study. Coagulation- and platelet-dependent thrombin generation (TG), measured by means of the calibrated automated thrombogram, were significantly decreased after in vitro and in vivo addition of rivaroxaban. As shown by a total thrombus-formation analysis approach, rivaroxaban treatment led to a significantly decreased coagulation-dependent (AR-chip) thrombus formation in patients treated with ASA plus P2Y12 inhibitor (clopidogrel/ticagrelor), whereas the pure platelet-dependent (PL-chip) thrombus formation was not affected at all. Adjunctive rivaroxaban therapy was not associated with significant differences in platelet aggregation assessed by light-transmission aggregometry (LTA). Nevertheless, according to fluorescence-activated cell sorter analysis, VLD rivaroxaban treatment resulted in a significantly reduced expression of platelet HMGB-1, whereas P-selectin exposure was not affected. Furthermore, an enhanced effect of rivaroxaban on total thrombus formation and TG was observed in particular in clopidogrel nonresponder patients defined as adenosine 5'-diphosphate-induced LTA ?40%. VLD rivaroxaban reduces thrombus formation and platelet-dependent TG in patients with ACS receiving DAPT, which can be of potential ischemic benefit. This trial was registered at www.clinicaltrials.gov as #NCT01417884.
Project description:BACKGROUND:Patients with established coronary artery disease or peripheral artery disease often have diabetes mellitus. These patients are at high risk of future vascular events. METHODS:In a prespecified analysis of the COMPASS trial (Cardiovascular Outcomes for People Using Anticoagulation Strategies), we compared the effects of rivaroxaban (2.5 mg twice daily) plus aspirin (100 mg daily) versus placebo plus aspirin in patients with diabetes mellitus versus without diabetes mellitus in preventing major vascular events. The primary efficacy end point was the composite of cardiovascular death, myocardial infarction, or stroke. Secondary end points included all-cause mortality and all major vascular events (cardiovascular death, myocardial infarction, stroke, or major adverse limb events, including amputation). The primary safety end point was a modification of the International Society on Thrombosis and Haemostasis criteria for major bleeding. RESULTS:There were 10?341 patients with diabetes mellitus and 17?054 without diabetes mellitus in the overall trial. A consistent and similar relative risk reduction was seen for benefit of rivaroxaban plus aspirin (n=9152) versus placebo plus aspirin (n=9126) in patients both with (n=6922) and without (n=11?356) diabetes mellitus for the primary efficacy end point (hazard ratio, 0.74, P=0.002; and hazard ratio, 0.77, P=0.005, respectively, Pinteraction=0.77) and all-cause mortality (hazard ratio, 0.81, P=0.05; and hazard ratio, 0.84, P=0.09, respectively; Pinteraction=0.82). However, although the absolute risk reductions appeared numerically larger in patients with versus without diabetes mellitus, both subgroups derived similar benefit (2.3% versus 1.4% for the primary efficacy end point at 3 years, Gail-Simon qualitative Pinteraction<0.0001; 1.9% versus 0.6% for all-cause mortality, Pinteraction=0.02; 2.7% versus 1.7% for major vascular events, Pinteraction<0.0001). Because the bleeding hazards were similar among patients with and without diabetes mellitus, the prespecified net benefit for rivaroxaban appeared particularly favorable in the patients with diabetes mellitus (2.7% versus 1.0%; Gail-Simon qualitative Pinteraction=0.001). CONCLUSIONS:In stable atherosclerosis, the combination of aspirin plus rivaroxaban 2.5 mg twice daily provided a similar relative degree of benefit on coronary, cerebrovascular, and peripheral end points in patients with and without diabetes mellitus. Given their higher baseline risk, the absolute benefits appeared larger in those with diabetes mellitus, including a 3-fold greater reduction in all-cause mortality. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01776424.
Project description:UNLABELLED: BACKGROUND: Arterial thrombosis triggered by vascular injury is a balance between thrombus growth and thrombus fragmentation (dethrombosis). Unbalance towards thrombus growth can lead to vascular occlusion, downstream ischemia and tissue damage.Here we describe the development of a simple methodology that allows for continuous real time monitoring and quantification of both processes during perfusion of human blood under arterial shear rate conditions. Using this methodology, we have studied the effects of antiplatelet agents targeting COX-1 (aspirin), P2Y12 (2-MeSAMP, clopidogrel), GP IIb-IIIa (eptifibatide) and their combinations on the kinetics of thrombosis over time. RESULTS: Untreated samples of blood perfused over type III collagen at arterial rates of shear promoted the growth of stable thrombi. Modulation by eptifibatide affected thrombus growth, while that mediated by 2-MeSAMP and aspirin affected thrombus stability. Using this technique, we confirmed the primacy of continuous signaling by the ADP autocrine loop acting on P2Y12 in the maintenance of thrombus stability. Analysis of the kinetics of thrombosis revealed that continuous and prolonged analysis of thrombosis is required to capture the role of platelet signaling pathways in their entirety. Furthermore, studies evaluating the thrombotic profiles of 20 healthy volunteers treated with aspirin, clopidogrel or their combination indicated that while three individuals did not benefits from either aspirin or clopidogrel treatments, all individuals displayed marked destabilization profiles when treated with the combination regimen. CONCLUSIONS: These results show the utility of a simple perfusion chamber technology to assess in real time the activity of antiplatelet drugs and their combinations. It offers the opportunity to perform pharmacodynamic monitoring of arterial thrombosis in clinical trials and to investigate novel strategies directed at inhibiting thrombus stability in the management of cardiovascular disease.
Project description:Left ventricular non-compaction cardiomyopathy (LVNC) is a rare heart disorder related to thrombosis. Anticoagulant therapy is suggested for the treatment of this disease. The success of the novel oral anticoagulant rivaroxaban as a treatment option for this disorder is unclear.A 43-year-old man who felt dizzy at rest was found to have an intraventricular thrombus.The thrombus was confirmed by echocardiography. And LVNC was diagnosed by cardiac magnetic resonance (CMR) and echocardiography.He was prescribed a low dose (10?mg daily) of rivaroxaban as treatment.After 3 months, the thrombus diminished, and the manifestation disappeared.Low dose of rivaroxaban may serve as a viable option for anticoagulation therapy in LVNC patients, with large clinical trials needed to determine the best course of treatment.
Project description:Background:Left ventricular thrombus (LVT), a common complication of acute ST-segment elevation myocardial infarction (STEMI), is associated with increased risk of systemic embolism and high mortality. Current STEMI guidelines recommend adding anticoagulant therapy to dual antiplatelet therapy (DAPT) if early-formulated LVT were detected, for which vitamin K antagonist (VKA) is the standard anticoagulant agent. The role of non-VKA oral anticoagulants (NOACs) in this scenario is uncertain. Methods:The EARLY-MYO-LVT study will be a prospective, multi-center and randomized trial designed to investigate the efficacy and safety of rivaroxaban versus warfarin in the treatment of post-STEMI LVT. It will enroll 280 patients with STEMI who have developed LVT within the first month of symptom onset. They will be randomized at 1:1 ratio into the group of rivaroxaban 15 mg daily or VKA treatment (with targeted INR 2-2.5) on the basis of standard DAPT (100 mg daily aspirin plus 75 mg daily clopidogrel) for 3-6 months. The primary efficacy endpoint will be the probability of LVT resolution after 3-month triple therapy, and the principal safety outcome will be the incidence of major bleeding events during the treatment. Discussion:The described study will systemically assess the efficacy and safety of NOACs-based anticoagulant therapy in the treatment of LVT subsequent to STEMI. Trial registration:The EARLY-MYO-LVT trial (Clinical trial number: NCT03764241).
Project description:Background The role of platelets in the development of vascular inflammation and endothelial dysfunction in the pathogenesis of hypertension is well established at this time. Aspirin is known to relieve pain, decrease fever, reduce inflammation, impair platelet aggregation, and prevent clotting, yet its effect in the context of salt-sensitive hypertension remains unclear. The present study investigated the importance of aspirin in inhibiting the abnormal activation of platelets and promoting the normal function of the vascular endothelium in a rat model of salt-sensitive hypertension. Method and Results Dahl salt-sensitive rats and salt-resistant rats were fed a normal-salt diet (4% NaCl), a high-salt diet (8% NaCl), or a high-salt diet with aspirin gavage (10 mg/kg per day) for 8 weeks. Blood pressure, platelet activation, vascular function, inflammatory response, and potential mechanism were measured. Low-dose aspirin (10 mg/kg per day) decreased the high-salt diet-induced elevation of blood pressure, platelet activation, leukocyte infiltration, and leukocyte-platelet aggregation (CD45+CD61+), as well as vascular endothelial and renal damage. These effects were related to the ability of aspirin to prevent the adhesion of leukocytes to endothelial cells via inhibition of the platelet cyclooxygenase 1 but not the cyclooxygenase 2 pathway. Aspirin also reversed the high-salt diet-induced abnormal activation of complement and coagulation cascades in platelets. Conclusions These results highlight a new property of aspirin in ameliorating vascular endothelial dysfunction induced by platelet activation, which may be beneficial in the treatment of salt-sensitive hypertension.