Z M Ruggeri

The Scripps Research Institute, لا هویا, California, United States

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Publications (326)2714.88 Total impact

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    ABSTRACT: Abstract Thrombin is a central regulator of leukocyte recruitment and inflammation at sites of vascular injury, a function thought to involve primarily endothelial PAR cleavage. Here we demonstrate the existence of a distinct leukocyte-trafficking mechanism regulated by components of the haemostatic system, including platelet PAR4, GPIbα and fibrin. Utilizing a mouse endothelial injury model we show that thrombin cleavage of platelet PAR4 promotes leukocyte recruitment to sites of vascular injury. This process is negatively regulated by GPIbα, as seen in mice with abrogated thrombin-platelet GPIbα binding (hGPIbα(D277N)). In addition, we demonstrate that fibrin limits leukocyte trafficking by forming a physical barrier to intravascular leukocyte migration. These studies demonstrate a distinct 'checkpoint' mechanism of leukocyte trafficking involving balanced thrombin interactions with PAR4, GPIbα and fibrin. Dysregulation of this checkpoint mechanism is likely to contribute to the development of thromboinflammatory disorders.
    No preview · Article · Jul 2015 · Nature Communications
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    ABSTRACT: Nonthrombotic platelet-endothelial interactions may contribute to atherosclerotic plaque development, although in vivo studies examining mechanism without platelet preactivation are lacking. Using in vivo molecular imaging at various stages of atherosclerosis, we quantified platelet-endothelial interactions and evaluated the contribution of major adhesion pathways. Mice deficient for the low-density lipoprotein receptor and Apobec-1 were studied as an age-dependent model of atherosclerosis at 10, 20, 30, and 40 weeks of age, which provided progressive increase in stage from early fatty streak (10 weeks) to large complex plaques without rupture (40 weeks). Platelet-targeted contrast ultrasound molecular imaging of the thoracic aorta performed with microbubbles targeted to GPIbα demonstrated selective signal enhancement as early as 10 weeks of age. This signal increased progressively with age (almost 8-fold increase from 10 to 40 weeks, analysis of variance P<0.001). Specificity for platelet targeting was confirmed by the reduction in platelet-targeted signal commensurate with the decrease in platelet count after immunodepletion with anti-GPIb or anti-CD41 antibody. Inhibition of P-selectin in 20 and 40 weeks atherosclerotic mice resulted in a small (15% to 30%) reduction in platelet signal. Molecular imaging with microbubbles targeted to the A1 domain of von Willebrand factor demonstrated selective signal enhancement at all time points, which did not significantly increase with age. Treatment of 20 and 40 week mice with recombinant ADAMTS13 eliminated platelet and von Willebrand factor molecular imaging signal. Platelet-endothelial interactions occur in early atherosclerosis. These interactions are in part caused by endothelial von Willebrand factor large multimers, which can be reversed with exogenous ADAMTS13. © 2015 American Heart Association, Inc.
    No preview · Article · Jul 2015 · Circulation Cardiovascular Imaging
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    ABSTRACT: Effector CD8(+) T cells (CD8 TE) play a key role during hepatotropic viral infections. Here, we used advanced imaging in mouse models of hepatitis B virus (HBV) pathogenesis to understand the mechanisms whereby these cells home to the liver, recognize antigens, and deploy effector functions. We show that circulating CD8 TE arrest within liver sinusoids by docking onto platelets previously adhered to sinusoidal hyaluronan via CD44. After the initial arrest, CD8 TE actively crawl along liver sinusoids and probe sub-sinusoidal hepatocytes for the presence of antigens by extending cytoplasmic protrusions through endothelial fenestrae. Hepatocellular antigen recognition triggers effector functions in a diapedesis-independent manner and is inhibited by the processes of sinusoidal defenestration and capillarization that characterize liver fibrosis. These findings reveal the dynamic behavior whereby CD8 TE control hepatotropic pathogens and suggest how liver fibrosis might reduce CD8 TE immune surveillance toward infected or transformed hepatocytes. Copyright © 2015 Elsevier Inc. All rights reserved.
    Full-text · Article · Apr 2015 · Cell
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    ABSTRACT: Extracellular ATP is a signal of tissue damage and induces macrophage responses that amplify inflammation and coagulation. Here we demonstrate that ATP signaling through macrophage P2X7 receptors uncouples the thioredoxin (TRX)/TRX reductase (TRXR) system and activates the inflammasome through endosome-generated ROS. TRXR and inflammasome activity promoted filopodia formation, cellular release of reduced TRX, and generation of extracellular thiol pathway-dependent, procoagulant microparticles (MPs). Additionally, inflammasome-induced activation of an intracellular caspase-1/calpain cysteine protease cascade degraded filamin, thereby severing bonds between the cytoskeleton and tissue factor (TF), the cell surface receptor responsible for coagulation activation. This cascade enabled TF trafficking from rafts to filopodia and ultimately onto phosphatidylserine-positive, highly procoagulant MPs. Furthermore, caspase-1 specifically facilitated cell surface actin exposure, which was required for the final release of highly procoagulant MPs from filopodia. Together, the results of this study delineate a thromboinflammatory pathway and suggest that components of this pathway have potential as pharmacological targets to simultaneously attenuate inflammation and innate immune cell-induced thrombosis.
    Preview · Article · Feb 2015 · Journal of Clinical Investigation
  • Z M Ruggeri · G L Mendolicchio
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    ABSTRACT: The initiation of thrombus formation at sites of vascular injury to secure haemostasis after tissue trauma requires the interaction of surface-exposed von Willebrand factor (VWF) with its primary platelet receptor, the glycoprotein (GP) Ib-IX-V complex. As an insoluble component of the extracellular matrix (ECM) of endothelial cells, VWF can directly initiate platelet adhesion. Circulating plasma VWF en-hances matrix VWF activity by binding to structures that become exposed to flowing blood, notably collagen type I and III in deeper layers of the vessel along with microfibrillar collagen type VI in the subendothelium. Moreover, plasma VWF is required to support platelet-to-platelet adhesion - i. e. aggregation - which promotes thrombus growth and consolidation. For these reasons, understanding how plasma VWF interaction with platelet receptors is regulated, particularly any distinctive features of GPIb binding to soluble as opposed to immobilized VWF, is of paramount importance in vascular biology. This brief review will highlight knowledge acquired and key problems that remain to be solved to elucidate fully the role of VWF in normal haemostasis and pathological thrombosis.
    No preview · Article · Jan 2015 · Hamostaseologie
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    Zaverio M Ruggeri
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    ABSTRACT: In this issue of Blood, Zhang and colleagues identify a structural motif in the α-subunit of the membrane glycoprotein (GP)Ib-IX-V complex that may explain how platelets sense mechanical force while responding to vascular injury.1
    Preview · Article · Jan 2015 · Blood

  • No preview · Article · Jan 2015 · Cancer Research

  • No preview · Article · Nov 2014 · Thrombosis and Haemostasis
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    ABSTRACT: The pathogenesis of atherosclerosis involves the interplay of haematopoietic, stromal and endothelial cells. Platelet interactions with endothelium and leukocytes are pivotal for atherosclerosis promotion. Glycoprotein (GP) Ibα is the ligand-binding subunit of the platelet GPIb-IX-V receptor complex; its deficiency causes the Bernard-Soulier syndrome (BSS), characterised by absent platelet GPIb-IX-V, macrothrombocytopenia and bleeding. We designed this study to determine the role of platelet GPIbα in the pathogenesis of atherosclerosis using two unique knockout models. Ldlr-/- mice were reconstituted with wild-type (wt), GPIbα-/- (lacks GPIbα) or chimeric IL-4R/GPIbα-Tg (lacks GPIbα extracellular domain) bone marrow and assayed for atherosclerosis development after feeding with pro-atherogenic "western diet". Here, we report that Ldlr-/-mice reconstituted with GPIbα-/- bone marrow developed less atherosclerosis compared to wt controls; accompanied by augmented accumulation of pro-inflammatory CD11b+ and CD11c+ myeloid cells, reduced oxLDL uptake and decreased TNF and IL 12p35 gene expression in the aortas. Flow cytometry and live cell imaging in whole blood-perfused microfluidic chambers revealed reduced platelet-monocyte aggregates in GPIbα-/- mice, which resulted in decreased monocyte activation. Interestingly, Ldlr-/-mice reconstituted with IL-4R/GPIbα-Tg bone marrow, producing less abnormal platelets, showed atherosclerotic lesions similar to wt mice. Platelet interaction with blood monocytes and accumulation of myeloid cells in the aortas was also essentially unaltered. Moreover, only complete GPIbα ablation altered platelet microparticles and CCL5 chemokine production. Thus, atherosclerosis reduction in mice lacking GPIbα may not result from the defective GPIbα-ligand binding, but more likely is a consequence of functional defects of GPIbα-/- platelets and reduced blood platelet counts.
    Full-text · Article · Aug 2014 · Thrombosis and Haemostasis
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    ABSTRACT: The outcome of a viral infection reflects the balance between virus virulence and host susceptibility. The clone 13 (Cl13) variant of lymphocytic choriomeningitis virus-a prototype of Old World arenaviruses closely related to Lassa fever virus-elicits in C57BL/6 and BALB/c mice abundant negative immunoregulatory molecules, associated with T-cell exhaustion, negligible T-cell-mediated injury, and high virus titers that persist. Conversely, here we report that in NZB mice, despite the efficient induction of immunoregulatory molecules and high viremia, Cl13 generated a robust cytotoxic T-cell response, resulting in thrombocytopenia, pulmonary endothelial cell loss, vascular leakage, and death within 6-8 d. These pathogenic events required type I IFN (IFN-I) signaling on nonhematopoietic cells and were completely abrogated by IFN-I receptor blockade. Thus, IFN-I may play a prominent role in hemorrhagic fevers and other acute virus infections associated with severe vascular pathology, and targeting IFN-I or downstream effector molecules may be an effective therapeutic approach.
    Preview · Article · Jun 2014 · Proceedings of the National Academy of Sciences
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    ABSTRACT: Tumor cell tissue factor (TF)-initiated coagulation supports hematogenous metastasis by fibrin formation, platelet activation, and monocyte/macrophage recruitment. Recent studies identified host anticoagulant mechanisms as a major impediment for successful hematogenous tumor cell metastasis. Here we address mechanisms that contribute to enhanced metastasis in hyperthrombotic mice with functional thrombomodulin deficiency (TM(P) (ro) mice). Pharmacological and genetic approaches were combined to characterize relevant thrombin targets in a mouse model of experimental hematogenous metastasis. TF-dependent, but contact pathway-independent syngeneic breast cancer metastasis was associated with marked platelet hyper-reactivity and formation of leukocyte-platelet aggregates in immune-competent TM(P) (ro) mice. Blockade of CD11b or genetic deletion of platelet glycoprotein Ibα excluded contributions of these receptors to enhanced platelet-dependent metastasis in hyperthrombotic mice. Mice with very low levels of the endothelial protein C receptor (EPCR) did not phenocopy the enhanced metastasis seen in TM(P) (ro) mice. Genetic deletion of the thrombin receptor PAR1 or endothelial thrombin signaling targets alone did not diminish enhanced metastasis in TM(P) (ro) mice. Combined deficiency of PAR1 on tumor cells and the host reduced metastasis in TM(P) (ro) mice. Metastasis in the hyperthrombotic TM(P) (ro) mouse model is mediated by platelet hyper-reactivity and contributions of PAR1 signaling on tumor and host cells. This article is protected by copyright. All rights reserved.
    Full-text · Article · Nov 2013 · Journal of Thrombosis and Haemostasis
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    ABSTRACT: Antioxidative drugs continue to be developed for the treatment of atherosclerosis. Apocynin is an nicotinamide adenine dinucleotide phosphate oxidase inhibitor with anti-inflammatory properties. We used contrast-enhanced ultrasound molecular imaging to assess whether short-term apocynin therapy in atherosclerosis reduces vascular oxidative stress and endothelial activation APPROACH AND RESULTS: Genetically modified mice with early atherosclerosis were studied at baseline and after 7 days of therapy with apocynin (4 mg/kg per day IP) or saline. Contrast-enhanced ultrasound molecular imaging of the aorta was performed with microbubbles targeted to vascular cell adhesion molecule 1 (VCAM-1; MBV), to platelet glycoprotein Ibα (MBPl), and control microbubbles (MBCtr). Aortic vascular cell adhesion molecule 1 was measured using Western blot. Aortic reactive oxygen species generation was measured using a lucigenin assay. Hydroethidine oxidation was used to assess aortic superoxide generation. Baseline signal for MBV (1.3±0.3 AU) and MBPl (1.5±0.5 AU) was higher than for MBCtr (0.5±0.2 AU; P<0.01). In saline-treated animals, signal did not significantly change for any microbubble agent, whereas short-term apocynin significantly (P<0.05) reduced vascular cell adhesion molecule 1 and platelet signal (MBV: 0.3±0.1; MBPl: 0.4±0.1; MBCtr: 0.3±0.2 AU; P=0.6 between agents). Apocynin reduced aortic vascular cell adhesion molecule 1 expression by 50% (P<0.05). However, apocynin therapy did not reduce reactive oxygen species content, superoxide generation, or macrophage content. Short-term treatment with apocynin in atherosclerosis reduces endothelial cell adhesion molecule expression. This change in endothelial phenotype can be detected by molecular imaging before any measurable decrease in macrophage content and is not associated with a detectable change in oxidative burden.
    Full-text · Article · Aug 2013 · Arteriosclerosis Thrombosis and Vascular Biology

  • No preview · Conference Paper · Jul 2013
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    ABSTRACT: Thrombosis promotes leukocyte infiltration into inflamed tissues, leading to organ injury in a broad range of diseases; however, the mechanisms by which thrombi guide leukocytes to sites of vascular injury remain ill-defined. Using mouse models of endothelial injury (traumatic or ischemia reperfusion), we demonstrate a distinct process of leukocyte recruitment, termed "directed intravascular migration," specifically mediated by platelet thrombi. Single adherent platelets and platelet aggregates stimulated leukocyte shape change at sites of endothelial injury; however, only thrombi were capable of inducing directed intravascular leukocyte migration. Leukocyte recruitment and migration induced by platelet thrombi occurred most prominently in veins but could also occur in arteries following ischemia-reperfusion injury. In vitro studies demonstrated a major role for platelet-derived NAP-2 (CXCL-7) and its CXCR1/2 receptor in regulating leukocyte polarization and motility. In vivo studies demonstrated the presence of an NAP-2 chemotactic gradient within the thrombus body. Pharmacologic blockade of CXCR1/2 as well as genetic deletion of NAP-2 markedly reduced leukocyte shape change and intrathrombus migration. These studies define a distinct process of leukocyte migration that is initiated by homotypic adhesive interactions between platelets, leading to the development of an NAP-2 chemotactic gradient within the thrombus body that guides leukocytes to sites of vascular injury.
    Full-text · Article · Apr 2013 · Blood
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    David Habart · Yann Cheli · Diane J Nugent · Zaverio M Ruggeri · Thomas J Kunicki
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    ABSTRACT: We have engineered a transgenic mouse on a C57BL/6 background that bears a floxed Itga2 gene. The crossing of this mouse strain to transgenic mice expressing Cre recombinase driven by the megakaryocyte (MK)-specific Pf4 promoter permits the conditional knockout of Itga2 in the MK/platelet lineage. Mice lacking MK α2β1 develop normally, are fertile, and like their systemic α2β1 knockout counterparts, exhibit defective adhesion to and aggregation induced by soluble type I collagen and a delayed onset to low dose fibrillar collagen-induced aggregation, results consistent with blockade or loss of platelet α2β1. At the same time, we observed a significant reduction in mean platelet volume, which is consistent with the reported role of α2β1 in MK maturation and proplatelet formation in vivo. This transgenic mouse strain bearing a floxed Itga2 gene will prove valuable to distinguish in vivo the temporal and spatial contributions of α2 integrin in selected cell types.
    Full-text · Article · Jan 2013 · PLoS ONE
  • Zaverio M. Ruggeri · Shaun P. Jackson

    No preview · Chapter · Jan 2013
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    ABSTRACT: Background: In atherosclerosis, local generation of reactive oxygen species amplifies the inflammatory response and contributes to plaque vulnerability. We used molecular imaging to test whether inhibition of NADPH oxidase with apocynin would reduce endothelial inflammatory activation and endothelial-platelet interactions, thereby interrupting progression to high-risk plaque phenotype. Methods and results: Mice deficient for both the low-density lipoprotein receptor and Apobec-1 were studied at 30 weeks of age and again after 10 weeks with or without apocynin treatment (10 or 50 mg/kg per day orally). In vivo molecular imaging of vascular cell adhesion molecule-1 (VCAM 1) P-selectin, and platelet glycoprotein-1bα (GPIbα) in the thoracic aorta was performed with targeted contrast-enhanced ultrasound molecular imaging. Arterial elastic modulus and pulse wave transit time were assessed using ultrahigh frequency ultrasound and invasive hemodynamic measurements. Plaque size and composition were assessed by histology. Molecular imaging in nontreated mice detected a 2-fold increase in P-selectin expression, VCAM-1 expression, and platelet adhesion between 30 and 40 weeks of age. Apocynin reduced all of these endothelial events in a dose-dependent fashion (25% and 50% reduction in signal at 40 weeks for low- and high-dose apocynin). Apocynin also decreased aortic elastic modulus and increased the pulse transit time. On histology, apocynin reduced total monocyte accumulation in a dose-dependent manner as well as platelet adhesion, although total plaque area was reduced in only the high-dose apocynin treatment group. Conclusions: Inhibition of NADPH oxidase in advanced atherosclerosis reduces endothelial activation and platelet adhesion, which are likely responsible for the arrest of plaque growth and improvement of vascular mechanical properties.
    No preview · Article · Dec 2012 · Circulation Cardiovascular Imaging

  • No preview · Article · Oct 2012 · Thrombosis Research
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    ABSTRACT: It has been shown that β(2) -glycoprotein I (β(2) GPI) interacts with von Willebrand factor (VWF) in a glycoprotein (GP)Ib binding state. Given the presence of active VWF multimers in thrombotic thrombocytopenic purpura (TTP), we speculated that β(2) GPI might play a role in TTP. We found that β(2) GPI plasma levels were significantly lower in acute and remission TTP patients than in normal controls, showing a direct correlation with ADAMTS 13 levels and an inverse correlation with the extent of VWF activation. In vitro flow experiments demonstrated that β(2) GPI can block platelet adhesion to endothelial cell-derived VWF strings. We confirmed the direct binding of β(2) GPI to VWF by surface plasmon resonance, and determined that domain I of β(2) GPI is the binding site of VWF A1 domain. Adhesion of β(2) GPI to erythrocytes and platelets was increased in the presence of active VWF, indicating that β(2) GPI may be cleared from the circulation during TTP episodes together with blood cells. Our findings suggest that β(2) GPI may protect from the effects of hyper-functional VWF by inhibiting its interaction with platelets.
    Full-text · Article · Aug 2012 · British Journal of Haematology
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    ABSTRACT: Platelets are a paradigm for a drug carrier in blood owing to their unique physical and biochemical properties. Here, we report the development of synthetic particles that mimic several physical features and important functional properties of platelets. These synthetic platelets have therapeutic and diagnostic applications for platelet associated disorders.
    No preview · Article · Jul 2012 · Advanced Materials

Publication Stats

22k Citations
2,714.88 Total Impact Points


  • 1988-2015
    • The Scripps Research Institute
      • Department of Molecular and Experimental Medicine
      لا هویا, California, United States
  • 2006
    • Ludwig-Maximilians-University of Munich
      München, Bavaria, Germany
  • 2002-2004
    • CRO Centro di Riferimento Oncologico di Aviano
      • Division of Medical Oncology A
      Aviano, Friuli Venezia Giulia, Italy
  • 1969-2004
    • University of Milan
      • • Angelo Bianchi Bonomi Hemophilia and Thrombosis Center
      • • Department of Internal Medicine
      Milano, Lombardy, Italy
  • 1989-1999
    • Mario Negri Institute for Pharmacological Research
      • Department of Biomedical Engineering
      Milano, Lombardy, Italy
    • St. Luke's Hospital
      CID, Iowa, United States
  • 1998
    • Children's Hospital of Orange County
      Orange, California, United States
  • 1995
    • Torrey Pines Institute for Molecular Studies
      Port St. Lucie, Florida, United States
  • 1993
    • Columbia University
      • College of Physicians and Surgeons
      New York, New York, United States
  • 1992
    • Shinshu University
      Shonai, Nagano, Japan
  • 1987-1991
    • Fujita Health University
      • • Department of Biomedical Polymer Science
      • • School of Medicine
      Nagoya, Aichi, Japan
    • Universidad de Salamanca
      Helmantica, Castille and León, Spain
  • 1985
    • James A. Haley Veterans Hospital
      Tampa, Florida, United States
  • 1983
    • State University of New York Upstate Medical University
      Syracuse, New York, United States
  • 1974
    • Lund University
      Lund, Skåne, Sweden