Bruce A Sullenger

Duke University, Durham, North Carolina, United States

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Publications (152)1240.91 Total impact

  • Youngju Lee · Johannes H Urban · Li Xu · Bruce A Sullenger · Jaewoo Lee
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    ABSTRACT: Although the use of RNAs has enormous therapeutic potential, these RNA-based therapies can trigger unwanted inflammatory responses by the activation of pattern recognition receptors (PRRs) and cause harmful side effects. In contrast, the immune activation by therapeutic RNAs can be advantageous for treating cancers. Thus, the immunogenicity of therapeutic RNAs should be deliberately controlled depending on the therapeutic applications of RNAs. In this study, we demonstrated that RNAs containing 2'fluoro (2'F) pyrimidines differentially controlled the activation of PRRs. The activity of RNAs that stimulate toll-like receptors 3 and 7 was abrogated by the incorporation of 2'F pyrimidine. By contrast, incorporation of 2'F pyrimidines enhanced the activity of retinoic acid-inducible gene 1-stimulating RNAs. Furthermore, we found that transfection with RNAs containing 2'F pyrimidine and 5' triphosphate (5'ppp) increased cell death and interferon-β expression in human cancer cells compared with transfection with 2'hydroxyl 5'ppp RNAs, whereas RNAs containing 2'O-methyl pyrimidine and 5'ppp completely abolished the induction of cell death and cytokine expression in the cells. Our findings suggest that incorporation of 2'F and 2'O-methyl nucleosides is a facile approach to differentially control the ability of therapeutic RNAs to activate or limit immune and inflammatory responses depending on therapeutic applications.
    No preview · Article · Jan 2016

  • No preview · Article · Dec 2015 · Journal of Allergy and Clinical Immunology
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    ABSTRACT: Potent and rapid-onset anticoagulation is required for several clinical settings, including cardiopulmonary bypass surgery. In addition, because anticoagulation is associated with increased bleeding following surgery, the ability to rapidly reverse such robust anticoagulation is also important. Previously, we observed that no single aptamer was as potent as heparin for anticoagulating blood. However, we discovered that combinations of two aptamers were as potent as heparin. Herein, we sought to combine two individual anticoagulant aptamers into a single bivalent RNA molecule in an effort to generate a single molecule that retained the potent anticoagulant activity of the combination of individual aptamers. We created four bivalent aptamers that can inhibit Factor X/Xa and prothrombin/thrombin and anticoagulate plasma, as well as the combination of individual aptamers. Detailed characterization of the shortest bivalent aptamer indicates that each aptamer retains full binding and functional activity when presented in the bivalent context. Finally, reversal of this bivalent aptamer with a single antidote was explored, and anticoagulant activity could be rapidly turned off in a dose-dependent manner. These studies demonstrate that bivalent anticoagulant aptamers represent a novel and potent approach to actively and reversibly control coagulation.
    No preview · Article · Nov 2015
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    Ying Zhang · Kyle Phua · Hon Fai Chan · Bruce Sullenger · Kam W. Leong

    Full-text · Article · Sep 2015 · Journal of Controlled Release
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    Rebecca S Woodruff · Bruce A Sullenger
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    ABSTRACT: As a novel class of therapeutics, aptamers, or nucleic acid ligands, have garnered clinical interest because of the ease of isolating a highly specific aptamer against a wide range of targets, their chemical flexibility and synthesis, and their inherent ability to have their inhibitory ability reversed. The following review details the development and molecular mechanisms of aptamers targeting specific proteases in the coagulation cascade. The ability of these anticoagulant aptamers to bind to and inhibit exosite function rather than binding within the active site highlights the importance of exosites in blocking protein function. As both exosite inhibitors and reversible agents, the use of aptamers is a promising strategy for future therapeutics. © 2015 American Heart Association, Inc.
    Preview · Article · Aug 2015 · Arteriosclerosis Thrombosis and Vascular Biology
  • Bethany Powell Gray · Linsley Kelly · Matthew Levy · Bruce A. Sullenger

    No preview · Article · Aug 2015 · Cancer Research
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    ABSTRACT: Cardiovascular disease is the leading cause of death in the United States. Heart failure is a common, costly, and potentially fatal condition that is inadequately managed by pharmaceuticals. Cardiac repair therapies are promising alternative options. A potential cardiac repair therapy involves reprogramming human fibroblasts toward an induced cardiac progenitor-like state. We developed a clinically useful and safer reprogramming method by nonintegrative delivery of a cocktail of cardiac transcription factor-encoding mRNAs into autologous human dermal fibroblasts obtained from skin biopsies. Using this method, adult and neonatal dermal fibroblasts were reprogrammed into cardiac progenitor cells (CPCs) that expressed c-kit, Isl-1, and Nkx2.5. Furthermore, these reprogrammed CPCs differentiated into cardiomyocytes (CMs) in vitro as judged by increased expression of cardiac troponin T, α-sarcomeric actinin, RyR2, and SERCA2 and displayed enhanced caffeine-sensitive calcium release. The ability to reprogram patient-derived dermal fibroblasts into c-kit(+) CPCs and differentiate them into functional CMs provides clinicians with a potential new source of CPCs for cardiac repair from a renewable source and an alternative therapy in the treatment of heart failure.
    No preview · Article · Jul 2015 · Stem Cells and Development
  • Elizabeth D. Pratico · Smita K. Nair · Bruce A. Sullenger

    No preview · Conference Paper · May 2015
  • Jaewoo Lee · Youngju Lee · Bruce A. Sullenger

    No preview · Article · Oct 2014 · Cancer Research
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    ABSTRACT: Background: Pathologic cutaneous scarring affects over 40 million people worldwide and costs billions of dollars annually. Understanding mechanisms of fibroblast activation and granulation tissue contraction is the first step toward preventing pathologic scarring. The authors hypothesize that nucleic acids increase fibroblast activation and cause granulation tissue contraction and that sequestration of nucleic acids by application of a nucleic acid scavenger dendrimer, polyamidoamine third-generation dendrimer, will decrease pathologic scarring. Methods: In vitro experiments were performed to assess the effect of nucleic acids on pathologic scar-associated fibroblast activity. The effect of nucleic acids on cytokine production and migration on mouse fibroblasts was evaluated. Immunofluorescence microscopy was used to determine the effect of nucleic acids on the differentiation of human primary fibroblasts into myofibroblasts. Using a murine model, the effect of polyamidoamine third-generation dendrimer on granulation tissue contraction was evaluated by gross and histologic parameters. Results: Mouse fibroblasts stimulated with nucleic acids had increased cytokine production (i.e., transforming growth factor-β, monocyte chemotactic protein 1, interleukin-10, tumor necrosis factor-α, and interferon-γ), migration, and differentiation into myofibroblasts. Polyamidoamine third-generation dendrimer blocked cytokine production, migration, and differentiation into myofibroblasts. Using a murine model of granulation tissue contraction, polyamidoamine third-generation dendrimer decreased wound contraction and angiogenesis. Collagen deposition in polyamidoamine third-generation dendrimer-treated tissues was aligned more randomly and whorl-like compared with control tissue. Conclusions: The data demonstrate that nucleic acid-stimulated fibroblast activation and granulation tissue contraction are blocked by polyamidoamine third-generation dendrimer. Sequestration of pathogen-associated molecular patterns may be an approach for preventing pathologic scarring.
    No preview · Article · Sep 2014 · Plastic & Reconstructive Surgery
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    ABSTRACT: Coordinated enzymatic reactions regulate blood clot generation. To explore the contributions of various coagulation enzymes in this process, we utilized a panel of aptamers against factors VIIa, IXa, Xa, and prothrombin. Each aptamer dose-dependently inhibited clot formation, yet none was able to completely impede this process in highly procoagulant settings. However, several combinations of two aptamers synergistically impaired clot formation. One extremely potent aptamer combination was able to maintain human blood fluidity even during extracorporeal circulation, a highly procoagulant setting encountered during cardiopulmonary bypass surgery. Moreover, this aptamer cocktail could be rapidly reversed with antidotes to restore normal hemostasis, indicating that even highly potent aptamer combinations can be rapidly controlled. These studies highlight the potential utility of using sets of aptamers to probe the functions of proteins in molecular pathways for research and therapeutic ends.
    Full-text · Article · Jul 2014 · Chemistry & Biology
  • Hemraj A. Juwarker · Eda K. Holl · Yeh-Hsing Lao · Kam W. Leong · Bruce A. Sullenger

    No preview · Conference Paper · May 2014
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    ABSTRACT: β-arrestins, ubiquitous cellular scaffolding proteins that act as signaling mediators of numerous critical cellular pathways, are attractive therapeutic targets because they promote tumorigenesis in several tumor models. However, targeting scaffolding proteins with traditional small molecule drugs has been challenging. Inhibition of β-arrestin 2 with a novel aptamer impedes multiple oncogenic signaling pathways simultaneously. Additionally, delivery of the β-arrestin 2-targeting aptamer into leukemia cells through coupling to a recently described cancer cell-specific delivery aptamer, inhibits multiple β-arrestin-mediated signaling pathways known to be required for chronic myelogenous leukemia (CML) disease progression, and impairs tumorigenic growth in CML patient samples. The ability to target scaffolding proteins such as β-arrestin 2 with RNA aptamers may prove beneficial as a therapeutic strategy. An RNA aptamer inhibits β-arrestin 2 activity.Inhibiting β-arrestin 2 impedes multiple tumorigenic pathways simultaneously.The therapeutic aptamer is delivered to cancer cells using a cell-specific DNA aptamer.Targeting β-arrestin 2 inhibits tumor progression in CML models and patient samples.
    Full-text · Article · Apr 2014 · PLoS ONE

  • No preview · Article · Mar 2014
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    Partha Ray · Bruce A Sullenger · Rebekah R White
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    ABSTRACT: Posttranslational modifications on proteins can serve as useful biomarkers for disease. However, their discovery and detection in biological fluids is challenging. Aptamers are oligonucleotide ligands that demonstrate high affinity toward their target proteins and can discriminate closely related proteins with superb specificity. Previously, we generated a cyclophilin B aptamer (M9-5) that could discriminate sera from pancreatic cancer patients and healthy volunteers with high specificity and sensitivity. In our present work we further characterize the aptamer and the target protein, cyclophilin B, and demonstrate that the aptamer could discriminate between cyclophilin B expressed in human cells versus bacteria. Using mass-spectrometric analysis, we discovered post-translational modifications on cyclophilin B that might be responsible for the M9-5 selectivity. The ability to distinguish between forms of the same protein with differing post-translational modifications is an important advantage of aptamers as tools for identification and detection of biomarkers.
    Full-text · Article · Oct 2013
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    ABSTRACT: Toll-like receptor (TLR) family members, 3, 7 and 9 are key components in initiation and progression of autoimmune disorders such as systemic lupus erythematosus (SLE). These TLRs are often referred to as nucleic acid-sensing TLRs based on their ability to recognize DNAs or RNAs produced by pathogens or damaged cells. During autoimmune disease progression these receptors recognize self nucleic acids as well as self nucleic acid-containing complexes and contribute to inflammatory cytokine production and subsequent enhancement of serum autoantibody levels. We have recently discovered that nucleic-acid scavenging polymers (NASPs) can neutralize the proinflammatory effects of nucleic acids. Here, we begin to explore what effects such NASPs have on normal immune function. We show that such NASPs can inhibit TLR activation without affecting nucleic acid-independent T cell activation. Moreover, we observe that stimulation of immune cells by encapsulated nucleic acids, such as those found in viral particles, is unaffected by NASPs. Thus NASPs only limit the activation of the immune system by accessible extra-cellular nucleic acid and do not engender non-specific immune suppression. These important findings suggest that NASPs represent a new approach toward anti-inflammatory drug development as these agents can potentially be utilized to block overt autoimmune disorders and inflammation while allowing normal immune responses to occur.
    Preview · Article · Jul 2013 · PLoS ONE
  • R S Woodruff · Y Xu · J Layzer · W Wu · M L Ogletreee · B A Sullenger
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    ABSTRACT: Background: Exposure of the plasma protein factor XII (FXII) to an anionic surface generates activated FXII that not only triggers the intrinsic pathway of blood coagulation through the activation of FXI but also mediates various vascular responses through activation of the plasma contact system. While deficiencies of FXII are not associated with excessive bleeding, thrombosis models in factor-deficient animals have suggested that this protein contributes to stable thrombus formation. Therefore, FXII has emerged as an attractive therapeutic target to treat or prevent pathological thrombosis formation without increasing the risk for hemorrhage. Objectives: Using an in vitro directed evolution and chemical biology approach, we sought to isolate a nuclease-resistant RNA aptamer that binds specifically to FXII and directly inhibits FXII coagulant function. Methods and results: We describe the isolation and characterization of a high-affinity RNA aptamer targeting FXII/activated FXII (FXIIa) that dose dependently prolongs fibrin clot formation and thrombin generation in clinical coagulation assays. This aptamer functions as a potent anticoagulant by inhibiting the autoactivation of FXII, as well as inhibiting intrinsic pathway activation (FXI activation). However, the aptamer does not affect the FXIIa-mediated activation of the proinflammatory kallikrein-kinin system (plasma kallikrein activation). Conclusions: We have generated a specific and potent FXII/FXIIa aptamer anticoagulant that offers targeted inhibition of discrete macromolecular interactions involved in the activation of the intrinsic pathway of blood coagulation.
    No preview · Article · May 2013 · Journal of Thrombosis and Haemostasis
  • J. E. Bond · E. Holl · M. A. Selim · B. Sullenger · H. Levinson

    No preview · Article · Mar 2013 · Wound Repair and Regeneration
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    Elizabeth D Pratico · Bruce A Sullenger · Smita K Nair
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    ABSTRACT: Induction of an effective immune response that can target and eliminate malignant cells or virus-infected cells requires the stimulation of antigen-specific effector T cells. A productive and long-lasting memory response requires 2 signals: a specific signal provided by antigen recognition through engagement of the T cell receptor and a secondary signal via engagement of costimulatory molecules (such as OX40) on these newly activated T cells. The OX40-OX40-ligand interaction is critical for the generation of productive effector and memory T cell functions. Thus agonistic antibodies that stimulate OX40 on activated T cells have been used as adjuvants to augment immune responses. We previously demonstrated that an aptamer modified to stimulate murine OX40 enhanced vaccine-mediated immune responses in a murine melanoma model. In this study, we describe the development of an agonistic aptamer that targets human OX40 (hOX40). This hOX40 aptamer was isolated using systematic evolution of ligands by exponential enrichment and binds the target purified protein with high affinity [dissociation constants (K(d))<10 nM]. Moreover, the hOX40 aptamer-streptavidin complex has an apparent binding affinity of ∼50 nM for hOX40 on activated T cells as determined by flow cytometry and specifically binds activated human T cells. A multivalent version of the aptamer, but not a mutant version of the aptamer, was able to stimulate OX40 on T cells and enhance cell proliferation and interferon-gamma production. Future studies will assess the therapeutic potential of hOX40 aptamers for ex vivo stimulation of antigen specific T cells in conjunction with dendritic cell-based vaccines for adoptive cellular therapy.
    Full-text · Article · Oct 2012
  • Anandi Krishnan · Erwin A Vogler · Bruce A Sullenger · Richard C Becker
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    ABSTRACT: The anticoagulant properties of a novel RNA aptamer that binds FIXa depend collectively on the intensity of surface contact activation of human blood plasma, aptamer concentration, and its binding affinity for FIXa. Accordingly, anticoagulation efficiency of plasma containing any particular aptamer concentration is low when coagulation is strongly activated by hydrophilic surfaces compared to the anticoagulation efficiency in plasma that is weakly activated by hydrophobic surfaces. Anticoagulation efficiency is lower at hypothermic temperatures possibly because aptamer-FIXa binding decreases with decreasing temperatures. Experimental results demonstrating these trends are qualitatively interpreted in the context of a previously established model of anticoagulation efficiency of thrombin-binding DNA aptamers that exhibit anticoagulation properties similar to the FIXa aptamer. In principle, FIXa aptamer anticoagulants should be more efficient and therefore more clinically useful than thrombin-binding aptamers because aptamer binding to FIXa competes only with FX that is at much lower blood concentration than fibrinogen (FI) that competes with thrombin-binding aptamers. Our findings may have translatable relevance in the application of aptamer anticoagulants for clinical conditions in which blood is in direct contact with non-biological surfaces such as those encountered in cardiopulmonary bypass circuits.
    No preview · Article · Oct 2012 · Journal of Thrombosis and Thrombolysis

Publication Stats

7k Citations
1,240.91 Total Impact Points

Institutions

  • 1998-2015
    • Duke University
      • Department of Surgery
      Durham, North Carolina, United States
  • 1995-2014
    • Duke University Medical Center
      • Department of Surgery
      Durham, North Carolina, United States
    • Mental Health Center of Denver
      Denver, Colorado, United States
  • 2007-2011
    • Translational Genomics Research Institute
      Phoenix, Arizona, United States
  • 1994
    • Howard Hughes Medical Institute
      Ashburn, Virginia, United States
  • 1990-1992
    • Memorial Sloan-Kettering Cancer Center
      • Division of Molecular Biology
      New York City, NY, United States