Efficacy of cilostazol on platelet reactivity and cardiovascular outcomes in patients undergoing percutaneous coronary intervention: insights from a meta-analysis of randomised trials

Background: Cilostazol overcomes high on-treatment platelet reactivity (HTPR) and reduces adverse cardiovascular (CV) outcomes after percutaneous coronary intervention (PCI). However, the role for triple antiplatelet therapy (TAPT) with cilostazol in addition to aspirin and clopidogrel after PCI is not well defined. Methods: We conducted a MEDLINE/EMBASE/CENTRAL search for randomised trials, until May 2014, evaluating TAPT compared with dual antiplatelet therapy (DAPT) of aspirin and clopidogrel alone in patients undergoing PCI and reporting platelet reactivity and/or CV outcomes. The primary platelet reactivity outcome was differences in platelet reactivity unit (PRU) with secondary outcomes of %platelet inhibition and rate of HTPR. The primary CV outcome was major adverse cardiovascular events (MACE), with secondary outcomes of death, cardiovascular death, myocardial infarction, stent thrombosis (ST), target lesion revascularisation (TLR) and target vessel revascularisation (TVR) as well as safety outcomes of bleeding and drug discontinuations. Results: In 17 trials that evaluated platelet reactivity outcomes, the mean PRU value was 47.73 units lower with TAPT versus DAPT (95% CI −61.41 to −34.04, p<0.0001; mean PRU 182.90 vs 232.65). TAPT also increased platelet inhibition by 12.71% (95% CI 10.76 to 14.67, p<0.0001), and led to a 60% reduction in the risk of HTPR (relative risk=0.40; 95% CI 0.30 to 0.53) compared with DAPT. Moreover, among the 34 trials that evaluated CV outcomes, TAPT reduced the risk of MACE (incident rate ratio (IRR)=0.68; 95% CI 0.60 to 0.78), TLR (IRR=0.57; 95% CI 0.44 to 0.73), TVR (IRR=0.69; 95% CI 0.59 to 0.81) and ST (IRR=0.63; 95% CI 0.40 to 0.98) with no difference for other outcomes including bleeding, even in trials using drug-eluting stents. Drug discontinuation due to adverse effects was, however, higher with TAPT vs DAPT (IRR=1.59; 95% CI 1.32 to 1.91). Conclusions: In patients undergoing PCI, addition of cilostazol to DAPT results in decreased platelet reactivity and a significant reduction in CV outcomes including ST, even in the drug-eluting stent era

Statins Suppress Apolipoprotein CIII-Induced Vascular Endothelial Cell Activation and Monocyte Adhesion

Aims: Activation of vascular endothelial cells (ECs) contributes importantly to inflammation and atherogenesis. We previously reported that apolipoprotein CIII (apoCIII), found abundantly on circulating triglyceride-rich lipoproteins, enhances adhesion of human monocytes to ECs in vitro. Statins may exert lipid-independent anti-inflammatory effects. The present study examined whether statins suppress apoCIII-induced EC activation in vitro and in vivo. Methods and results: Physiologically relevant concentrations of purified human apoCIII enhanced attachment of the monocyte-like cell line THP-1 to human saphenous vein ECs (HSVECs) or human coronary artery ECs (HCAECs) under both static and laminar shear stress conditions. This process mainly depends on vascular cell adhesion molecule-1 (VCAM-1), as a blocking VCAM-1 antibody abolished apoCIII-induced monocyte adhesion. ApoCIII significantly increased VCAM-1 expression in HSVECs and HCAECs. Pre-treatment with statins suppressed apoCIII-induced VCAM-1 expression and monocyte adhesion, with two lipophilic statins (pitavastatin and atorvastatin) exhibiting inhibitory effects at lower concentration than those of hydrophilic pravastatin. Nuclear factor κB (NF-κB) mediated apoCIII-induced VCAM-1 expression, as demonstrated via loss-of-function experiments, and pitavastatin treatment suppressed NF-κB activation. Furthermore, in the aorta of hypercholesterolaemic $Ldlr^{−/−}$ mice, pitavastatin administration in vivo suppressed VCAM-1 mRNA and protein, induced by apoCIII bolus injection. Similarly, in a subcutaneous dorsal air pouch mouse model of leucocyte recruitment, apoCIII injection induced F4/80+ monocyte and macrophage accumulation, whereas pitavastatin administration reduced this effect. Conclusions: These findings further establish the direct role of apoCIII in atherogenesis and suggest that anti-inflammatory effects of statins could improve vascular disease in the population with elevated plasma apoCIII

Accumulation of Tissue Factor into Developing Thrombi In Vivo Is Dependent upon Microparticle P-Selectin Glycoprotein Ligand 1 and Platelet P-Selectin

Using a laser-induced endothelial injury model, we examined thrombus formation in the microcirculation of wild-type and genetically altered mice by real-time in vivo microscopy to analyze this complex physiologic process in a system that includes the vessel wall, the presence of flowing blood, and the absence of anticoagulants. We observe P-selectin expression, tissue factor accumulation, and fibrin generation after platelet localization in the developing thrombus in arterioles of wild-type mice. However, mice lacking P-selectin glycoprotein ligand 1 (PSGL-1) or P-selectin, or wild-type mice infused with blocking P-selectin antibodies, developed platelet thrombi containing minimal tissue factor and fibrin. To explore the delivery of tissue factor into a developing thrombus, we identified monocyte-derived microparticles in human platelet–poor plasma that express tissue factor, PSGL-1, and CD14. Fluorescently labeled mouse microparticles infused into a recipient mouse localized within the developing thrombus, indicating that one pathway for the initiation of blood coagulation in vivo involves the accumulation of tissue factor– and PSGL-1–containing microparticles in the platelet thrombus expressing P-selectin. These monocyte-derived microparticles bind to activated platelets in an interaction mediated by platelet P-selectin and microparticle PSGL-1. We propose that PSGL-1 plays a role in blood coagulation in addition to its known role in leukocyte trafficking

Accumulation of Tissue Factor Into Developing Thrombi In Vivo Is Dependent Upon Microparticle P-Selectin Glycoprotein Ligand 1 And Platelet P-Selectin

Using a laser-induced endothelial injury model, we examined thrombus formation in the microcirculation of wild-type and genetically altered mice by real-time in vivo microscopy to analyze this complex physiologic process in a system that includes the vessel wall, the presence of flowing blood, and the absence of anticoagulants. We observe P-selectin expression, tissue factor accumulation, and fibrin generation after platelet localization in the developing thrombus in arterioles of wild-type mice. However, mice lacking P-selectin glycoprotein ligand 1 (PSGL-1) or P-selectin, or wild-type mice infused with blocking P-selectin antibodies, developed platelet thrombi containing minimal tissue factor and fibrin. To explore the delivery of tissue factor into a developing thrombus, we identified monocyte-derived microparticles in human platelet–poor plasma that express tissue factor, PSGL-1, and CD14. Fluorescently labeled mouse microparticles infused into a recipient mouse localized within the developing thrombus, indicating that one pathway for the initiation of blood coagulation in vivo involves the accumulation of tissue factor– and PSGL-1–containing microparticles in the platelet thrombus expressing P-selectin. These monocyte-derived microparticles bind to activated platelets in an interaction mediated by platelet P-selectin and microparticle PSGL-1. We propose that PSGL-1 plays a role in blood coagulation in addition to its known role in leukocyte trafficking

Modulation of the ATM/autophagy pathway by a G-quadruplex ligand tips the balance between senescence and apoptosis in cancer cells

G-quadruplex ligands exert their antiproliferative effects through telomere-dependent and telomere-independent mechanisms, but the inter-relationships among autophagy, cell growth arrest and cell death induced by these ligands remain largely unexplored. Here, we demonstrate that the G-quadruplex ligand 20A causes growth arrest of cancer cells in culture and in a HeLa cell xenografted mouse model. This response is associated with the induction of senescence and apoptosis. Transcriptomic analysis of 20A treated cells reveals a significant functional enrichment of biological pathways related to growth arrest, DNA damage response and the lysosomal pathway. 20A elicits global DNA damage but not telomeric damage and activates the ATM and autophagy pathways. Loss of ATM following 20A treatment inhibits both autophagy and senescence and sensitizes cells to death. Moreover, disruption of autophagy by deletion of two essential autophagy genes ATG5 and ATG7 leads to failure of CHK1 activation by 20A and subsequently increased cell death. Our results, therefore, identify the activation of ATM by 20A as a critical player in the balance between senescence and apoptosis and autophagy as one of the key mediators of such regulation. Thus, targeting the ATM/autophagy pathway might be a promising strategy to achieve the maximal anticancer effect of this compound

The Antioxidant Protein Peroxiredoxin 4 Is Epigenetically Down Regulated in Acute Promyelocytic Leukemia

The antioxidant peroxiredoxin (PRDX) protein family comprises 6 members, which are implicated in a variety of cellular responses, including growth factor signal transduction. PRDX4 resides in the endoplasmic reticulum (ER), where it locally controls oxidative stress by reducing H2O2levels. We recently provided evidence for a regulatory function of PRDX4 in signal transduction from a myeloid growth factor receptor, the granulocyte colony-stimulating factor receptor (G-CSFR). Upon activation, the ligand-induced G-CSFR undergoes endocytosis and routes via the early endosomes where it physically interacts with ER-resident PRDX4. PRDX4 negatively regulates G-CSFR mediated signaling. Here, we investigated whether PRDX4 is affected in acute myeloid leukemia (AML); genomic alterations and expression levels of PRDX4 were investigated. We show that genomic abnormalities involving PRDX4 are rare in AML. However, we find a strong reduction in PRDX4 expression levels in acute promyelocytic leukemia (APL) compared to normal promyelocytes and different molecular subtypes of AML. Subsequently, the possible role of DNA methylation and histone modifications in silencing of PRDX4 in APLs was investigated. We show that the reduced expression is not due to methylation of the CpG island in the promoter region of PRDX4 but correlates with increased trimethylation of histone 3 lysine residue 27 (H3K27me3) and lysine residue 4 (H3K4me3) at the transcriptional start site (TSS) of PRDX4, indicative of a bivalent histone code involved in transcriptional silencing. These findings suggest that the control of G-CSF responses by the antioxidant protein PRDX4 may be perturbed in APL

Myeloid-related protein 8/14 and the risk of cardiovascular death or myocardial infarction after an acute coronary syndrome in the Pravastatin or Atorvastatin Evaluation and Infection Theraphy: Thrombolysis in Myocardial Infarction (PROVE IT-TIMI 22) trial

Background Using a transcriptional profiling approach, we recently identified myeloid-related protein 8/14 (MRP-8/14) to be expressed by platelets during acute myocardial infarction (MI). Elevated concentrations of MRP-8/14 are associated with a higher risk for future cardiovascular events in apparently healthy individuals but have not been assessed with respect to prognosis in patients with acute coronary syndrome. Methods We performed a nested case-control study (n = 237 case-control pairs) among patients enrolled in the Pravastatin or Atorvastatin Evaluation and Infection Theraphy: Thrombolysis in Myocardial Infarction 22 (PROVE IT-TIMI 22) trial (mean follow-up 24 months) to investigate the risk of cardiovascular death or MI associated with MRP-8/14 measured at 30 days after an acute coronary syndrome. Results Patients with cardiovascular death or MI after 30 days (cases) had higher median [25th, 75th percentile] MRP-8/14 levels than patients who remained free of recurrent events (5.6 [2.8, 13.5] mg/L vs 4.0 [1.9, 10.1] mg/L, P = .020). The risk of a recurrent cardiovascular event increased with each increasing quartile of MRP-8/14 ( P-trend = 0.007) such that patients with the highest levels had a 2.0-fold increased odds (95% CI 1.1-3.6, P = .029) of a recurrent event after adjusting for standard risk indicators, randomized treatment, and C-reactive protein. Patients with elevated levels of MRP-8/14 and high-sensitivity C-reactive protein showed significantly increased risk of cardiovascular death or MI compared with patients with the lowest levels of both markers (adjusted odds ratio 2.1, 95% CI 1.2-3.8). Conclusions Myeloid-related protein 8/14 may be a useful biomarker of platelet and inflammatory disease activity in atherothrombosis and may serve as a novel target for therapeutic intervention

CD47 plays a critical role in T-cell recruitment by regulation of LFA-1 and VLA-4 integrin adhesive functions

CD47 plays an important but incompletely understood role in the innate and adaptive immune responses. CD47, also called integrin-associated protein, has been demonstrated to associate in cis with β1 and β3 integrins. Here we test the hypothesis that CD47 regulates adhesive functions of T-cell α4β1 (VLA-4) and αLβ2 (LFA-1) in in vivo and in vitro models of inflammation. Intravital microscopy studies reveal that CD47(−/−) Th1 cells exhibit reduced interactions with wild-type (WT) inflamed cremaster muscle microvessels. Similarly, murine CD47(−/−) Th1 cells, as compared with WT, showed defects in adhesion and transmigration across tumor necrosis factor-α (TNF-α)–activated murine endothelium and in adhesion to immobilized intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion protein 1 (VCAM-1) under flow conditions. Human Jurkat T-cells lacking CD47 also showed reduced adhesion to TNF-α–activated endothelium and ICAM-1 and VCAM-1. In cis interactions between Jurkat T-cell β2 integrins and CD47 were detected by fluorescence lifetime imaging microscopy. Unexpectedly, Jurkat CD47 null cells exhibited a striking defect in β1 and β2 integrin activation in response to Mn(2+) or Mg(2+)/ethylene glycol tetraacetic acid treatment. Our results demonstrate that CD47 associates with β2 integrins and is necessary to induce high-affinity conformations of LFA-1 and VLA-4 that recognize their endothelial cell ligands and support leukocyte adhesion and transendothelial migration