vorapaxar and Inflammation

Acute pulmonary and cardiac injury remain significant causes of morbidity and mortality in those afflicted with severe pneumococcal disease, with the risk for early mortality often persisting several years beyond clinical recovery. Although remaining to be firmly established in the clinical setting, a considerable body of evidence, mostly derived from murine models of experimental infection, has implicated the pneumococcal, cholesterol-binding, pore-forming toxin, pneumolysin (Ply), in the pathogenesis of lung and myocardial dysfunction. Topics covered in this review include the burden of pneumococcal disease, risk factors, virulence determinants of the pneumococcus, complications of severe disease, antibiotic and adjuvant therapies, as well as the structure of Ply and the role of the toxin in disease pathogenesis. Given the increasing recognition of the clinical potential of Ply-neutralisation strategies, the remaining sections of the review are focused on updates of the types, benefits and limitations of currently available therapies which may attenuate, directly and/or indirectly, the injurious actions of Ply. These include recently described experimental therapies such as various phytochemicals and lipids, and a second group of more conventional agents the members of which remain the subject of ongoing clinical evaluation. This latter group, which is covered more extensively, encompasses macrolides, statins, corticosteroids, and platelet-targeted therapies, particularly aspirin.

Topics: Adrenal Cortex Hormones; Animals; Bacterial Proteins; Chemotherapy, Adjuvant; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Inflammation; Lactones; Lung; Macrolides; Mice; Platelet Aggregation Inhibitors; Pneumococcal Infections; Pneumonia, Pneumococcal; Pyridines; Risk Factors; Streptococcus pneumoniae; Streptolysins

Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease with a 5-year mortality rate of > 50% and unknown etiology. Treatment options remain limited and, currently, only two drugs are available, i.e. nintedanib and pirfenidone. However, both of these antifibrotic agents only slow down the progression of the disease, and do not remarkably prolong the survival of IPF patients. Hence, the discovery of new therapeutic targets for IPF is crucial. Studies exploring the mechanisms that are involved in IPF have identified several possible targets for therapeutic interventions. Among these, blood coagulation factor receptors, i.e. protease-activated receptors (PARs), are key candidates, as these receptors mediate the cellular effects of coagulation factors and play central roles in influencing inflammatory and fibrotic responses. In this review, we will focus on the controversial role of the coagulation cascade in the pathogenesis of IPF. In the light of novel data, we will attempt to reconciliate the apparently conflicting data and discuss the possibility of pharmacologic targeting of PARs for the treatment of fibroproliferative diseases.

Topics: Animals; Anticoagulants; Bleomycin; Blood Coagulation; Blood Coagulation Factors; Disease Models, Animal; Disease Progression; Fibrosis; Humans; Idiopathic Pulmonary Fibrosis; Inflammation; Lactones; Mice; Platelet Aggregation Inhibitors; Pyridines; Receptor, PAR-1; Receptor, PAR-2; Receptors, Proteinase-Activated

The protease-activated receptor-1 (PAR-1) is critically involved in the co-activation of coagulation and inflammatory responses. Vorapaxar is a reversible, orally active, low molecular weight, competitive antagonist of PAR-1.We investigated the effects of PAR-1 inhibition by vorapaxar on the inflammatory response, the activation of coagulation, fibrinolysis and endothelium during experimental endotoxemia. In this randomized, double blind, crossover trial, 16 healthy volunteers received a bolus infusion of 2 ng/kg lipopolysaccharide (LPS) ± placebo/vorapaxar with a washout period of 8 weeks. Vorapaxar dosing was guided by thrombin receptor-activating peptide-6-induced whole blood aggregometry. Participants received 10 mg vorapaxar or placebo as an initial dose and, depending on the aggregometry, potentially an additional 10 mg. Goal was > 80% inhibition of aggregation compared with baseline. Vorapaxar significantly reduced the LPS-induced increase in pro-thrombin fragments F1 + 2 by a median of 27% (quartiles: 11-49%), thrombin-anti-thrombin concentrations by 22% (-3 to 46%) and plasmin-anti-plasmin levels by 38% (23-53%). PAR-1 inhibition dampened peak concentrations of tumour necrosis factor -α, interleukin-6 and consequently C-reactive protein by 66% (-11-71%), 50% (15-79%) and 23% (16-38%), respectively. Vorapaxar decreased maximum von Willebrand factor levels by 29% (26-51%) and soluble E-selectin concentrations by 30% (25-38%) after LPS infusion. PAR-1 inhibition did not affect thrombomodulin, soluble P-selectin and platelet factor-4 concentrations.PAR-1 inhibition significantly reduced the activation of coagulation, fibrinolysis, the inflammatory response and endothelial activation during experimental human endotoxemia.

Topics: Administration, Oral; Adult; Anti-Inflammatory Agents; Anticoagulants; Austria; Biomarkers; Blood Coagulation; Blood Platelets; Cross-Over Studies; Double-Blind Method; Drug Monitoring; Endothelium, Vascular; Endotoxemia; Female; Fibrinolysis; Humans; Inflammation; Inflammation Mediators; Infusions, Intravenous; Lactones; Lipopolysaccharides; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Prospective Studies; Pyridines; Receptor, PAR-1; Signal Transduction; Time Factors

Increased D-dimer concentrations are associated with poor cardiovascular and other clinical outcomes in people with treated HIV infection. Proteinase activated receptor-1 (PAR-1) is activated by thrombin and overexpressed by immune cells from HIV-infected people. We aimed to study the efficacy of vorapaxar, a licensed inhibitor of PAR-1, in reducing HIV-associated hypercoagulation and inflammation.. This was a multicentre, double-blind, randomised, placebo-controlled trial done in seven hospital clinics in Australia and the USA. Eligible participants were HIV-infected, aviraemic, were receiving stable antiretroviral therapy, and had D-dimer concentrations greater than 200 ng/mL. We randomly assigned participants (1:1) using computer-generated block lists of size two to receive vorapaxar (2·5 mg orally daily) or matched placebo for 12 weeks. Participants were reviewed and had a blood sample taken at weeks 1, 4, 8, and 12 during treatment, and at a final visit at week 18. The primary endpoint was treatment group difference in changes from baseline D-dimer concentrations after 8-12 weeks of treatment, and was assessed in the modified intention-to-treat population (participants who had at least one dose of study drug or one follow-up visit). This trial is registered with ClinicalTrials.gov, number NCT02394730, and is closed to new participants.. Vorapaxar had no effect on D-dimer concentrations in HIV-infected patients receiving stable antiretroviral therapy but at risk of poor outcomes. Alternative approaches are needed to reduce hypercoagulation, inflammation, and adverse long-term outcomes in patients with treated HIV infection.. Australian National Health and Medical Research Council, US National Cancer Institute, National Institutes of Health.

Topics: Anti-HIV Agents; Biomarkers; Double-Blind Method; Female; Fibrin Fibrinogen Degradation Products; Hemorrhage; HIV Infections; Humans; Inflammation; Lactones; Male; Middle Aged; Platelet Aggregation Inhibitors; Pyridines; Receptor, PAR-1; T-Lymphocytes; Thrombophilia

Thromboembolic events are prevalent in chronic kidney disease (CKD) patients due to increased thrombin generation leading to a hypercoagulable state. We previously demonstrated that inhibition of protease-activated receptor-1 (PAR-1) by vorapaxar reduces kidney fibrosis.. We used an animal model of unilateral ischemia-reperfusion injury-induced CKD to explore the tubulovascular crosstalk mechanisms of PAR-1 in acute kidney injury (AKI)-to-CKD transition.. During the early phase of AKI, PAR-1-deficient mice exhibited reduced kidney inflammation, vascular injury, and preserved endothelial integrity and capillary permeability. During the transition phase to CKD, PAR-1 deficiency preserved kidney function and diminished tubulointerstitial fibrosis via downregulated transforming growth factor-β/Smad signaling. Maladaptive repair in the microvasculature after AKI further exacerbated focal hypoxia with capillary rarefaction, which was rescued by stabilization of hypoxia-inducible factor and increased tubular vascular endothelial growth factor A in PAR-1-deficient mice. Chronic inflammation was also prevented with reduced kidney infiltration by both M1- and M2-polarized macrophages. In thrombin-induced human dermal microvascular endothelial cells (HDMECs), PAR-1 mediated vascular injury through activation of NF-κB and ERK MAPK pathways. Gene silencing of PAR-1 exerted microvascular protection via a tubulovascular crosstalk mechanism during hypoxia in HDMECs. Finally, pharmacologic blockade of PAR-1 with vorapaxar improved kidney morphology, promoted vascular regenerative capacity, and reduced inflammation and fibrosis depending on the time of initiation.. Our findings elucidate a detrimental role of PAR-1 in vascular dysfunction and profibrotic responses upon tissue injury during AKI-to-CKD transition and provide an attractive therapeutic strategy for post-injury repair in AKI.

Topics: Acute Kidney Injury; Animals; Endothelial Cells; Fibrosis; Humans; Hypoxia; Inflammation; Kidney; Mice; Receptor, PAR-1; Renal Insufficiency, Chronic; Reperfusion Injury; Thrombin; Vascular Endothelial Growth Factor A; Vascular System Injuries

Protease-activated receptor 1 (PAR1) and toll-like receptors (TLRs) are inflammatory mediators contributing to atherogenesis and atherothrombosis. Vorapaxar, which selectively antagonizes PAR1-signaling, is an approved, add-on antiplatelet therapy for secondary prevention. The non-hemostatic, platelet-independent, pleiotropic effects of vorapaxar have not yet been studied.. PAR1 inhibition with vorapaxar may be effective in reducing residual thrombo-inflammatory event risk in patients with atherosclerosis independent of its effect on platelets.

Topics: Animals; Apolipoproteins E; Atherosclerosis; Female; Humans; Inflammation; Intercellular Adhesion Molecule-1; Lactones; Male; Mice; Mice, Knockout; Myocardium; Platelet Aggregation; Pyridines; Receptor, PAR-1; Thrombin; Toll-Like Receptor 2; Toll-Like Receptor 4; Vascular Cell Adhesion Molecule-1; Vascular Diseases

Vorapaxar is indicated with standard antiplatelet therapy (APT) in patients with a history of myocardial infarction (MI) or peripheral arterial disease (PAD).. To evaluate the comparative effects of vorapaxar on platelet-fibrin clot characteristics (PFCC), coagulation, inflammation, and platelet and endothelial function during treatment with daily 81 mg aspirin (A), 75 mg clopidogrel (C), both (C + A), or neither.. Thrombelastography, conventional platelet aggregation (PA), ex vivo endothelial function by ENDOPAT, coagulation, platelet activation/inflammation marked by urinary 11-dehydrothromboxane B. Vorapaxar had no effect on PFCC, ADP- or collagen-induced PA, thrombin time, fibrinogen, PT, PTT, von Willebrand factor (vWF), D-dimer, or endothelial function (P > .05 in all groups). Inhibition of SFLLRN (PAR-1 activating peptide)-stimulated PA by vorapaxar was accelerated by A + C at 2 hours (P < .05 versus other groups) with nearly complete inhibition by 30 days that persisted through 30 days after discontinuation in all groups (P < .001). SFLLRN-induced PA during offset was lower in APT patients versus APT-naïve patients (P < .05). Inhibition of UTxB. Vorapaxar had no influence on PFCC measured by thrombelastography, coagulation, or endothelial function irrespective of APT. Inhibition of protease activated receptor (PAR)-1 mediated platelet aggregation by vorapaxar was accelerated by A + C and offset was prolonged by concomitant APT. Vorapaxar-induced anti-inflammatory effects were observed in non-aspirin-treated patients.

Topics: Humans; Inflammation; Lactones; Platelet Aggregation Inhibitors; Pyridines

Protease-activated receptor (PAR)-1 has emerged as a key profibrotic player in various organs including kidney. PAR-1 activation leads to deposition of extracellular matrix (ECM) proteins in the tubulointerstitium and induction of epithelial-mesenchymal transition (EMT) during renal fibrosis. We tested the anti-fibrotic potential of vorapaxar, a clinically approved PAR-1 antagonist for cardiovascular protection, in an experimental kidney fibrosis model of unilateral ureteral obstruction (UUO) and an AKI-to-chronic kidney disease (CKD) transition model of unilateral ischemia-reperfusion injury (UIRI), and dissected the underlying renoprotective mechanisms using rat tubular epithelial cells. PAR-1 is activated mostly in the renal tubules in both the UUO and UIRI models of renal fibrosis. Vorapaxar significantly reduced kidney injury and ameliorated morphologic changes in both models. Amelioration of kidney fibrosis was evident from down-regulation of fibronectin (Fn), collagen and α-smooth muscle actin (αSMA) in the injured kidney. Mechanistically, inhibition of PAR-1 inhibited MAPK ERK1/2 and transforming growth factor-β (TGF-β)-mediated Smad signaling, and suppressed oxidative stress, overexpression of pro-inflammatory cytokines and macrophage infiltration into the kidney. These beneficial effects were recapitulated in cultured tubular epithelial cells in which vorapaxar ameliorated thrombin- and hypoxia-induced TGF-β expression and ECM accumulation. In addition, vorapaxar mitigated capillary loss and the expression of adhesion molecules on the vascular endothelium during AKI-to-CKD transition. The PAR-1 antagonist vorapaxar protects against kidney fibrosis during UUO and UIRI. Its efficacy in human CKD in addition to CV protection warrants further investigation.

Topics: Animals; Biomarkers; Cell Hypoxia; Endothelial Cells; Epithelial Cells; Epithelial-Mesenchymal Transition; Extracellular Matrix Proteins; Extracellular Signal-Regulated MAP Kinases; Fibrosis; Inflammation; Kidney; Kidney Tubules; Lactones; Macrophages; Mice, Inbred BALB C; Mice, Inbred C57BL; Oxidative Stress; Pyridines; Rats; Reactive Oxygen Species; Receptor, PAR-1; Reperfusion Injury; Smad3 Protein; Thrombin; Transforming Growth Factor beta; Up-Regulation; Ureteral Obstruction

Monocytes are activated in inflammatory conditions via a variety of cytokine receptors as well as in a procoagulatory setting through thrombin, acting upon protease-activated receptors (PARs). This study investigated the expression pattern of PAR1 and PAR3 on human monocyte subsets. Furthermore, a possible regulation of the expression of PAR1 and PAR3 in these cells by inflammatory activation were studied. CD16

Topics: Adaptor Proteins, Signal Transducing; Cell Cycle Proteins; Cells, Cultured; Endotoxemia; Healthy Volunteers; Humans; Inflammation; Lactones; Lipopolysaccharides; Monocytes; Plasminogen Activator Inhibitor 1; Pyridines; Receptor, PAR-1; Receptors, IgG; Thromboplastin; Transcriptome; Up-Regulation

Topics: Anti-Inflammatory Agents; Double-Blind Method; HIV; HIV Infections; Humans; Inflammation; Lactones; Pyridines

In addition to its central role in coagulation, thrombin is involved in non-hemostatic activities such as inflammation. Direct inhibition of thrombin activity (e.g. with dabigatran) or reducing its generation by inhibition of Factor Xa (e.g. with rivaroxaban) may therefore have anti-inflammatory effects.. Microarray experiments were performed to identify transcriptome-wide changes in mRNA expression levels induced by thrombin in the presence and absence of the PAR-1 antagonist vorapaxar in primary human umbilical vein endothelial cells (HUVECs). On this basis, HUVECs were incubated with recalcified plasma, with or without rivaroxaban (0.3-3000nM), dabigatran (0.3-10,000nM), or vorapaxar (0.3-10nM). Expression levels of preselected pro-inflammatory genes were quantified by real-time PCR.. Vorapaxar abolished 67 of the 69 transcripts altered by more than twofold on addition of thrombin to HUVECs. ELAM-1, VCAM-1, ICAM-1, MCP-1, IL-8, CXCL1, and CXCL2 were among the genes most strongly induced by thrombin. Inflammatory gene expression after stimulation of thrombin generation was concentration-dependently suppressed by vorapaxar, dabigatran, and rivaroxaban. However, dabigatran at low concentrations (3-300nM) increased significantly the expression levels of CXCL1, CXCL2, IL-8, ELAM-1, MCP-1, and tissue factor.. In HUVECs, plasma-induced transcriptional changes are mediated by thrombin-induced PAR-1 activation. Rivaroxaban downregulated the expression of pro-inflammatory markers and tissue factor to a similar extent to dabigatran.

Topics: Antithrombins; Dabigatran; Endothelial Cells; Factor Xa Inhibitors; Human Umbilical Vein Endothelial Cells; Humans; Inflammation; Lactones; Pyridines; Receptor, PAR-1; Rivaroxaban; Thrombin; Transcriptome

Protease-activated receptor-1 (PAR1) couples the coagulation cascade to platelet activation during myocardial infarction and to endothelial inflammation during sepsis. This receptor demonstrates marked signaling bias. Its activation by thrombin stimulates prothrombotic and proinflammatory signaling, whereas its activation by activated protein C (APC) stimulates cytoprotective and antiinflammatory signaling. A challenge in developing PAR1-targeted therapies is to inhibit detrimental signaling while sparing beneficial pathways. We now characterize a novel class of structurally unrelated small-molecule PAR1 antagonists, termed parmodulins, and compare the activity of these compounds to previously characterized compounds that act at the PAR1 ligand-binding site. We find that parmodulins target the cytoplasmic face of PAR1 without modifying the ligand-binding site, blocking signaling through Gαq but not Gα13 in vitro and thrombus formation in vivo. In endothelium, parmodulins inhibit prothrombotic and proinflammatory signaling without blocking APC-mediated pathways or inducing endothelial injury. In contrast, orthosteric PAR1 antagonists such as vorapaxar inhibit all signaling downstream of PAR1. Furthermore, exposure of endothelial cells to nanomolar concentrations of vorapaxar induces endothelial cell barrier dysfunction and apoptosis. These studies demonstrate how functionally selective antagonism can be achieved by targeting the cytoplasmic face of a G-protein-coupled receptor to selectively block pathologic signaling while preserving cytoprotective pathways.

Topics: Animals; Apoptosis; Binding Sites; Chlorocebus aethiops; COS Cells; Cytoplasm; Endothelium, Vascular; Exocytosis; Human Umbilical Vein Endothelial Cells; Humans; Inflammation; Lactones; Ligands; Platelet Aggregation Inhibitors; Protein C; Pyridines; Receptor, PAR-1; RNA, Small Interfering; Signal Transduction; Thrombosis