1
|
Lin FY, Li J, Xie Y, Zhu J, Huong Nguyen TT, Zhang Y, Zhu J, Springer TA. A general chemical principle for creating closure-stabilizing integrin inhibitors. Cell 2022; 185:3533-3550.e27. [PMID: 36113427 PMCID: PMC9494814 DOI: 10.1016/j.cell.2022.08.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 07/07/2022] [Accepted: 08/04/2022] [Indexed: 01/26/2023]
Abstract
Integrins are validated drug targets with six approved therapeutics. However, small-molecule inhibitors to three integrins failed in late-stage clinical trials for chronic indications. Such unfavorable outcomes may in part be caused by partial agonism, i.e., the stabilization of the high-affinity, extended-open integrin conformation. Here, we show that the failed, small-molecule inhibitors of integrins αIIbβ3 and α4β1 stabilize the high-affinity conformation. Furthermore, we discovered a simple chemical feature present in multiple αIIbβ3 antagonists that stabilizes integrins in their bent-closed conformation. Closing inhibitors contain a polar nitrogen atom that stabilizes, via hydrogen bonds, a water molecule that intervenes between a serine residue and the metal in the metal-ion-dependent adhesion site (MIDAS). Expulsion of this water is a requisite for transition to the open conformation. This change in metal coordination is general to integrins, suggesting broad applicability of the drug-design principle to the integrin family, as validated with a distantly related integrin, α4β1.
Collapse
Affiliation(s)
- Fu-Yang Lin
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jing Li
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Yonghua Xie
- School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, PRC
| | - Jianghai Zhu
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Thi Thu Huong Nguyen
- Blood Research Institute, Versiti, Milwaukee, WI 53226, USA; Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Yonghui Zhang
- School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, PRC.
| | - Jieqing Zhu
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Blood Research Institute, Versiti, Milwaukee, WI 53226, USA; Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
| | - Timothy A Springer
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
2
|
Abstract
INTRODUCTION Integrins are a family of 24 cell adhesion receptors that play a role in the biggest unmet needs in medicine - cardiovascular disease, immunology and cancer. Their discovery promised huge potential for the pharmaceutical industry. Areas covered. Over 35-years since their discovery, there is little to show for the hundreds of billions of dollars of investment in anti-integrin drug discovery programmes. In this review the author discusses the reasons for the failure of this promising class of drugs and the future for this class of drugs. Expert opinion. Within 10-years, there was a plethora of potent, specific anti-integrin molecules and since their discovery, many of these agents have entered clinical trials. The success in discovering these agents was due to recently discovered monoclonal antibody technology. The integrin-recognition domain Arg-Gly-Asp (RGD) provided the basis for discovering small molecule inhibitors to integrins - both cyclic peptides and peptidomimetics. Most agents failed in the Phase III clinical trials and those agents that did make it to the market were plagued with issues of toxicity and limited efficacy and were soon replaced with non-integrin targeting agents. Their failure was due to a combination of poor pharmacokinetics and pharmacodynamics, complicated by the complex pathophysiology of integrins.
Collapse
Affiliation(s)
- Dermot Cox
- School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland , Dublin, Ireland
| |
Collapse
|
3
|
Armstrong PC, Peter K. GPIIb/IIIa inhibitors: From bench to bedside and back to bench again. Thromb Haemost 2017; 107:808-14. [DOI: 10.1160/th11-10-0727] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 01/20/2012] [Indexed: 02/06/2023]
Abstract
SummaryFrom the discovery of the platelet glycoprotein (GP) IIb/IIIa and identification of its central role in haemostasis, the integrin GPIIb/IIIa (αIIbβ3, CD41/CD61) was destined to be an anti-thrombotic target. The subsequent successful development of intravenous ligand-mimetic inhibitors occurred during a time of limited understanding of integrin physiology. Although efficient inhibitors of ligand binding, they also mimic ligand function. In the case of GPIIb/IIIa inhibitors, despite strongly inhibiting platelet aggregation, paradoxical fibrinogen binding and platelet activation can occur. The quick progression to development of small-molecule orally available inhibitors meant that this approach inherited many potential flaws, which together with a short half-life resulted in an increase in mortality and a halt to the numerous pharmaceutical development programs. Limited clinical benefits, together with the success of other anti-thrombotic drugs, in particular P2Y12 ADP receptor blockers, have also led to a restrictive use of intravenous GPIIb/ IIIa inhibitors. However, with a greater understanding of this key platelet-specific integrin, GPIIb/IIIa remains a potentially attractive target and future drug developments will be better informed by the lessons learnt from taking the current inhibitors back to the bench. This overview will review the physiology behind the inherent problems of a ligand-based integrin inhibitor design and discuss novel promising approaches for GPIIb/IIIa inhibition.
Collapse
|
4
|
Bijak M, Dziedzic A, Saluk-Bijak J. Flavonolignans reduce the response of blood platelet to collagen. Int J Biol Macromol 2017; 106:878-884. [PMID: 28842200 DOI: 10.1016/j.ijbiomac.2017.08.091] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/29/2017] [Accepted: 08/14/2017] [Indexed: 01/25/2023]
Abstract
The primary biological function of platelets is to form hemostatic thrombi that prevent blood loss and maintain vascular integrity. These multi-responding cells are activated by different endogenous, physiological agonists due to the vast number of receptors present on the surface of the platelets. Collagen represents up to 40% of the total protein presented in the vessel wall and is the major activator of the platelets' response after tissue injury, and is the only matrix protein which supports both platelet adhesion and complete activation. The aim of our study was to determine the effects of three major flavonolignans (silybin, silychristin and silydianin) on collagen-induced blood platelets' activation, adhesion, aggregation and secretion of PF-4. We observed that depending on the dose, silychristin and silybin have anti-platelet properties observed as inhibition of collagen-induced activation (formation of blood platelet aggregates and microparticles, as well as decreased expression of P-selectin and activation of integrin αIIbβ3), aggregation, adhesion and secretion of PF-4. These effects highlight the potential of silybin and silychristin as supplementation to prevent primary and secondary thrombotic events wherein excessive blood platelet response to a physiological agonist is observed.
Collapse
Affiliation(s)
- Michal Bijak
- Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland.
| | - Angela Dziedzic
- Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland
| | - Joanna Saluk-Bijak
- Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland
| |
Collapse
|
5
|
Morel A, Rywaniak J, Bijak M, Miller E, Niwald M, Saluk J. Flow cytometric analysis reveals the high levels of platelet activation parameters in circulation of multiple sclerosis patients. Mol Cell Biochem 2017; 430:69-80. [PMID: 28210898 PMCID: PMC5437150 DOI: 10.1007/s11010-017-2955-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 01/28/2017] [Indexed: 12/25/2022]
Abstract
The epidemiological studies confirm an increased risk of cardiovascular disease in multiple sclerosis, especially prothrombotic events directly associated with abnormal platelet activity. The aim of our study was to investigate the level of blood platelet activation in the circulation of patients with chronic phase of multiple sclerosis (SP MS) and their reactivity in response to typical platelets’ physiological agonists. We examined 85 SP MS patients diagnosed according to the revised McDonald’s criteria and 50 healthy volunteers as a control group. The platelet activation and reactivity were assessed using flow cytometry analysis of the following: P-selectin expression (CD62P), activation of GP IIb/IIIa complex (PAC-1 binding), and formation of platelet microparticles (PMPs) and platelet aggregates (PA) in agonist-stimulated (ADP, collagen) and unstimulated whole blood samples. Furthermore, we measured the level of soluble P-selectin (sP-selectin) in plasma using ELISA method, to evaluate the in vivo level of platelet activation, both in healthy and SP MS subjects. We found a statistically significant increase in P-selectin expression, GP IIb/IIIa activation, and formation of PMPs and PA, as well as in unstimulated and agonist-stimulated (ADP, collagen) platelets in whole blood samples from patients with SP MS in comparison to the control group. We also determined the higher sP-selectin level in plasma of SP MS subjects than in the control group. Based on the obtained results, we might conclude that during the course of SP MS platelets are chronically activated and display hyperreactivity to physiological agonists, such as ADP or collagen.
Collapse
Affiliation(s)
- Agnieszka Morel
- Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236, Lodz, Poland.
| | - Joanna Rywaniak
- Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236, Lodz, Poland
| | - Michał Bijak
- Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236, Lodz, Poland
| | - Elżbieta Miller
- Department of Physical Medicine, Medical University of Lodz, Pl. Hallera 1, 90-647, Lodz, Poland.,Neurorehabilitation Ward, III General Hospital in Lodz, Milionowa 14, 93-113, Lodz, Poland
| | - Marta Niwald
- Department of Physical Medicine, Medical University of Lodz, Pl. Hallera 1, 90-647, Lodz, Poland.,Neurorehabilitation Ward, III General Hospital in Lodz, Milionowa 14, 93-113, Lodz, Poland
| | - Joanna Saluk
- Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236, Lodz, Poland
| |
Collapse
|
6
|
Celik E, Faridi MH, Kumar V, Deep S, Moy VT, Gupta V. Agonist leukadherin-1 increases CD11b/CD18-dependent adhesion via membrane tethers. Biophys J 2014; 105:2517-27. [PMID: 24314082 DOI: 10.1016/j.bpj.2013.10.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 10/09/2013] [Accepted: 10/18/2013] [Indexed: 01/13/2023] Open
Abstract
Integrin CD11b/CD18 is a key adhesion receptor that mediates leukocyte migration and immune functions. Leukadherin-1 (LA1) is a small molecule agonist that enhances CD11b/CD18-dependent cell adhesion to its ligand ICAM-1. Here, we used single-molecule force spectroscopy to investigate the biophysical mechanism by which LA1-activated CD11b/CD18 mediates leukocyte adhesion. Between the two distinct populations of CD11b/CD18:ICAM-1 complex that participate in cell adhesion, the cytoskeleton(CSK)-anchored elastic elements and the membrane tethers, we found that LA1 enhanced binding of CD11b/CD18 on K562 cells to ICAM-1 via the formation of long membrane tethers, whereas Mn(2+) additionally increased ICAM-1 binding via CSK-anchored bonds. LA1 activated wild-type and LFA1(-/-) neutrophils also showed longer detachment distances and time from ICAM-1-coated atomic force microscopy tips, but significantly lower detachment force, as compared to the Mn(2+)-activated cells, confirming that LA1 primarily increased membrane-tether bonds to enhance CD11b/CD18:ICAM-1 binding, whereas Mn(2+) induced additional CSK-anchored bond formation. The results suggest that the two types of agonists differentially activate integrins and couple them to the cellular machinery, providing what we feel are new insights into signal mechanotransduction by such agents.
Collapse
Affiliation(s)
- Emrah Celik
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida
| | | | | | | | | | | |
Collapse
|
7
|
The synthesis of 4,7-disubstituted-2H-benzo[b][1,4]-oxazin-3(4H)-ones using Smiles rearrangement and their in vitro evaluation as platelet aggregation inhibitors. Bioorg Med Chem Lett 2014; 24:1479-83. [PMID: 24565904 DOI: 10.1016/j.bmcl.2014.02.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 01/31/2014] [Accepted: 02/04/2014] [Indexed: 11/21/2022]
|
8
|
Mahalingam B, Ajroud K, Alonso JL, Anand S, Adair B, Horenstein AL, Malavasi F, Xiong JP, Arnaout MA. Stable coordination of the inhibitory Ca2+ ion at the metal ion-dependent adhesion site in integrin CD11b/CD18 by an antibody-derived ligand aspartate: implications for integrin regulation and structure-based drug design. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2011; 187:6393-401. [PMID: 22095715 PMCID: PMC3237904 DOI: 10.4049/jimmunol.1102394] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A central feature of integrin interaction with physiologic ligands is the monodentate binding of a ligand carboxylate to a Mg(2+) ion hexacoordinated at the metal ion-dependent adhesion site (MIDAS) in the integrin A domain. This interaction stabilizes the A domain in the high-affinity state, which is distinguished from the default low-affinity state by tertiary changes in the domain that culminate in cell adhesion. Small molecule ligand-mimetic integrin antagonists act as partial agonists, eliciting similar activating conformational changes in the A domain, which has contributed to paradoxical adhesion and increased patient mortality in large clinical trials. As with other ligand-mimetic integrin antagonists, the function-blocking mAb 107 binds MIDAS of integrin CD11b/CD18 A domain (CD11bA), but in contrast, it favors the inhibitory Ca(2+) ion over the Mg(2+) ion at MIDAS. We determined the crystal structures of the Fab fragment of mAb 107 complexed to the low- and high-affinity states of CD11bA. Favored binding of the Ca(2+) ion at MIDAS is caused by the unusual symmetric bidentate ligation of a Fab-derived ligand Asp to a heptacoordinated MIDAS Ca(2+) ion. Binding of the Fab fragment of mAb 107 to CD11bA did not trigger the activating tertiary changes in the domain or in the full-length integrin. These data show that the denticity of the ligand Asp/Glu can modify the divalent cation selectivity at MIDAS and hence integrin function. Stabilizing the Ca(2+) ion at MIDAS by bidentate ligation to a ligand Asp/Glu may provide one approach for designing pure integrin antagonists.
Collapse
Affiliation(s)
- Bhuvaneshwari Mahalingam
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Kaouther Ajroud
- Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Jose Luis Alonso
- Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Saurabh Anand
- Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Brian Adair
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Alberto L Horenstein
- Lab of Immunogenetics, University of Torino Medical School, 10126, Torino, Italy
| | - Fabio Malavasi
- Lab of Immunogenetics, University of Torino Medical School, 10126, Torino, Italy
| | - Jian-Ping Xiong
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - M. Amin Arnaout
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Address correspondence to: M. Amin Arnaout, Division of Nephrology, Massachusetts General Hospital, 149 13th Street, Charlestown, MA, 02129, Tel: 617-726-5663, Fax: 617-726-5671.
| |
Collapse
|
9
|
Cox D, Brennan M, Moran N. Integrins as therapeutic targets: lessons and opportunities. Nat Rev Drug Discov 2010; 9:804-20. [PMID: 20885411 DOI: 10.1038/nrd3266] [Citation(s) in RCA: 358] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The integrins are a large family of cell adhesion molecules that are essential for the regulation of cell growth and function. The identification of key roles for integrins in a diverse range of diseases, including cancer, infection, thrombosis and autoimmune disorders, has revealed their substantial potential as therapeutic targets. However, so far, pharmacological inhibitors for only three integrins have received marketing approval. This article discusses the structure and function of integrins, their roles in disease and the chequered history of the approved integrin antagonists. Recent advances in the understanding of integrin function, ligand interaction and signalling pathways suggest novel strategies for inhibiting integrin function that could help harness their full potential as therapeutic targets.
Collapse
Affiliation(s)
- Dermot Cox
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, 123 St Stephens Green, Dublin 2, Ireland.
| | | | | |
Collapse
|
10
|
Abrams J, Schroeder J, Frishman WH, Freedman J. Pharmacologic Options for Treatment of Ischemic Disease. Cardiovasc Ther 2007. [DOI: 10.1016/b978-1-4160-3358-5.50011-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
|
11
|
Scirica BM, Cannon CP, Cooper R, Aster RH, Brassard J, McCabe CH, Charlesworth A, Skene AM, Braunwald E. Drug-induced thrombocytopenia and thrombosis: Evidence from patients receiving an oral glycoprotein IIb/IIIa inhibitor in the Orbofiban in Patients with Unstable coronary Syndromes- (OPUS-TIMI 16) trial. J Thromb Thrombolysis 2006; 22:95-102. [PMID: 17008974 DOI: 10.1007/s11239-006-8669-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To assess etiology and impact of thrombocytopenia in a large oral glycoprotein (GP) IIb/IIIa inhibitor trial. BACKGROUND Heparin is known to cause thrombocytopenia, and in some of these patients thrombosis. GP IIb/IIIa inhibitors are also associated with thrombocytopenia. METHODS The Orbofiban in Patients with Unstable Coronary Syndromes (OPUS-TIMI 16) Trial randomized 10,392 patients with ACS to the oral GP IIb/IIIa inhibitor orbofiban or placebo. Patients were followed for a minimum of ten months. Thrombocytopenia was defined prospectively as a platelet count < 80,000. RESULTS Thrombocytopenia was rare in the OPUS-TIMI 16 trial (0.68% at Day 30 and 0.80% at 1 year), but more common in patients treated with orbofiban (0.92%) compared with those treated with placebo (0.2%), p < 0.001. Patients who developed thrombocytopenia had higher rates of death (11.6% vs. 1.7%, p < 0.001), recurrent MI (12.1% vs. 2.8%, p < 0.001), intracranial hemorrhage (2.9% vs. 0.0%, p < 0.001), and major or severe bleeding (19.0% vs. 2.0%, p < 0.001) at 30 days (with similar results at one year). CONCLUSION Thrombocytopenia, though uncommon, was associated with orbofiban use and an increased risk of bleeding, but also death and MI. This study provides further evidence that drugs that lead to thrombocytopenia are, in a significant proportion of patients associated with thrombotic events.
Collapse
Affiliation(s)
- Benjamin M Scirica
- TIMI Study Group, Cardiovascular Division, Brigham and Women's Hospital, 75 Francis st., Boston, MA 02115, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
Hemostasis is a normal process preventing the sequelae of uncontrolled hemorrhage. In certain settings, these same processes cause adverse clinical events due to thrombotic occlusion of a vessel. The majority of unstable coronary syndromes result from disruption of an atherosclerotic plaque, leading to the exposure of subintimal contents, which triggers coagulation and the formation of a platelet-rich thrombus. The central role of platelet activation in the events that lead to vessel occlusion is well known. However, this process is complex and influenced by a myriad of cellular and plasma-derived mediators that regulate the balance between occlusive and nonocclusive thrombosis.
Collapse
Affiliation(s)
- Jane E Freedman
- Boston University School of Medicine, Whitaker Cardiovascular Institute, Boston, MA 02118, USA.
| |
Collapse
|
13
|
Massa TM, Yang ML, Ho JYC, Brash JL, Santerre JP. Fibrinogen surface distribution correlates to platelet adhesion pattern on fluorinated surface-modified polyetherurethane. Biomaterials 2005; 26:7367-76. [PMID: 16026826 DOI: 10.1016/j.biomaterials.2005.05.063] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In previous work, it had been shown that platelet adhesion could be reduced by fluorinating surfaces with oligomeric fluoropolymers, referred to as surface-modifying macromolecules (SMMs). In the current study, two in vitro blood-contacting experiments were carried out on a polyetherurethane modified with three different SMMs in order to determine if altered platelet adhesion levels could be related to the pattern of adsorbed protein and more specifically to the manner in which fibrinogen (Fg) distribution occurs at the surface. In the first experiment, the materials were placed in whole human blood and the adherent platelets were viewed with high-resolution scanning electron microscopy (SEM). In a second experiment, the materials were incubated with human plasma with the absence of platelets. The plasma contained 5% fluorescent-Fg. The materials were then viewed with a fluorescence microscope and images were collected to define the distribution of high-density fluorescent-Fg areas. The SEM and fluorescent-Fg images were imported to Image Pro Plus imaging software to measure the area, length and circularity and a bivariate correlation test was conducted between the two sets of data. For area and length morphology parameters, there were high and significant correlations (r > 0.9, p < 0.05) between the platelets and Fg aggregates. The data suggest that the Fg distribution may serve as a predictor of platelet morphology/activation and provides insight into the non-thrombogenic character of biomaterials containing the fluorinated SMMs.
Collapse
Affiliation(s)
- T M Massa
- Department of Chemical Engineering and Applied Science, University of Toronto, Ont., Canada
| | | | | | | | | |
Collapse
|
14
|
Reynolds AR, Reynolds LE, Nagel TE, Lively JC, Robinson SD, Hicklin DJ, Bodary SC, Hodivala-Dilke KM. Elevated Flk1 (vascular endothelial growth factor receptor 2) signaling mediates enhanced angiogenesis in beta3-integrin-deficient mice. Cancer Res 2005; 64:8643-50. [PMID: 15574772 DOI: 10.1158/0008-5472.can-04-2760] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tumor growth, tumor angiogenesis, and vascular endothelial growth factor (VEGF)-specific angiogenesis are all enhanced in beta(3)-integrin-null mice. Furthermore, endothelial cells isolated from beta(3)-null mice show elevated levels of Flk1 (VEGF receptor 2) expression, suggesting that beta(3)-integrin can control the amplitude of VEGF responses by controlling Flk1 levels or activity. We now show that Flk1 signaling is required for the enhanced tumor growth and angiogenesis seen in beta(3)-null mice. Moreover, beta(3)-null endothelial cells exhibit enhanced migration and proliferation in response to VEGF in vitro, and this phenotype requires Flk1 signaling. Upon VEGF stimulation, beta(3)-null endothelial cells exhibit higher levels of phosphorylated Flk1 and extracellular-related kinases 1 and 2 than wild-type endothelial cells. Furthermore, signaling via ERK1/2 is required to mediate the elevated responses to VEGF observed in beta(3)-null endothelial cells and aortic rings in vitro. These data confirm that VEGF signaling via Flk1 is enhanced in beta(3)-integrin-deficient mice and suggests that this increase may mediate the enhanced angiogenesis and tumor growth observed in these mice in vivo.
Collapse
MESH Headings
- Animals
- Cell Growth Processes/physiology
- Cell Movement/physiology
- Endothelium, Vascular/growth & development
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/pathology
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Female
- Integrin alphaVbeta3/physiology
- Integrin beta3/physiology
- Lung Neoplasms/blood supply
- Lung Neoplasms/metabolism
- Male
- Melanoma, Experimental/blood supply
- Melanoma, Experimental/metabolism
- Mice
- Mice, Inbred C57BL
- Neoplasms, Experimental/blood supply
- Neoplasms, Experimental/metabolism
- Neoplasms, Experimental/pathology
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- Signal Transduction/physiology
- Vascular Endothelial Growth Factor A/metabolism
- Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors
- Vascular Endothelial Growth Factor Receptor-2/metabolism
- Vascular Endothelial Growth Factor Receptor-2/physiology
Collapse
Affiliation(s)
- Andrew R Reynolds
- Tumour Biology Laboratory, Cancer Research UK Clinical Centre, Barts and the London, Queen Mary's School of Medicine and Dentistry, John Vane Science Centre, London, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Anderluh M, Cesar J, Stefanic P, Kikelj D, Janes D, Murn J, Nadrah K, Tominc M, Addicks E, Giannis A, Stegnar M, Dolenc MS. Design and synthesis of novel platelet fibrinogen receptor antagonists with 2H-1,4-benzoxazine-3(4H)-one scaffold. A systematic study. Eur J Med Chem 2005; 40:25-49. [PMID: 15642407 DOI: 10.1016/j.ejmech.2004.09.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Revised: 09/01/2004] [Accepted: 09/06/2004] [Indexed: 11/29/2022]
Abstract
New platelet glycoprotein IIb/IIIa (GP IIb/IIIa, integrin alpha(IIb)beta3) antagonists were prepared on a 2H-1,4-benzoxazine-3(4H)-one scaffold. Their anti-aggregatory activities in human platelet rich plasma and their affinity towards alpha(IIb)beta3 and alpha(V)beta3 integrins were assessed. Various substitution positions and side chain variations were studied. In contrast to the generally accepted model, compounds containing ethyl esters as aspartate mimetics were in general more active than the corresponding free acids. We suggest an explanation for the observed behaviour of these new compounds.
Collapse
Affiliation(s)
- Marko Anderluh
- Faculty of Pharmacy, University of Ljubljana, Askerceva 7, 1000 Ljubljana, Slovenia
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Mehrotra MM, Heath JA, Smyth MS, Pandey A, Rose JW, Seroogy JM, Volkots DL, Nannizzi-Alaimo L, Park GL, Lambing JL, Hollenbach SJ, Scarborough RM. Discovery of Novel 2,8-Diazaspiro[4.5]decanes as Orally Active Glycoprotein IIb-IIIa Antagonists. J Med Chem 2004; 47:2037-61. [PMID: 15056002 DOI: 10.1021/jm030354b] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In our efforts to develop orally active GPIIb-IIIa antagonists with improved pharmaceutical properties, we have utilized a novel 2,8-diazaspiro[4.5]decane scaffold as a template. We describe here our investigation of a variety of templates including spiropiperidinyl-gamma-lactams, spiropiperidinylimide, spiropiperidinylureas, and spiropiperidinylhydantoins. With the appropriate acidic and basic pharmacophores in place, each template yielded analogues with potent GPIIb-IIIa inhibitory activity. One of the compounds, 59 (CT50787), was also used to demonstrate for the first time the use of a pharmacological agent which is alphaIIbbeta3 specific to display biological activity in a lower species such as mouse and to extend bleeding times. Evaluation of the pharmacokinetic properties of selected compounds from each series in rat, dog, and cynomolgus monkey has led to the identification of 22 (CT51464), a double prodrug, with excellent pharmacokinetic properties. It exhibited good pharmacokinetic profile across species (F% = 33 (Cyno), 73 (dog), 22 (rat); t(1/2)(beta)() = 14.2 h (Cyno), 8.97 h (dog), 1.81 h (rat)). The biologically active form, 23 (CT50728), displayed inhibition of platelet aggregation in platelet rich plasma (PRP) with an IC(50) value of 53 nM in citrate buffer, 110 nM in PPACK anticoagulated PRP, and 4 nM in solid-phase GPIIb-IIIa competition binding assay (ELISA). Both 23 and 22 were stable in human liver microsomes, did not inhibit the P450 3A4 isozyme, and had low protein binding (18.22% for 23) and a desirable log P (0.45 +/- 0.06 for 22, and -0.91 +/- 0.32 for 23). It is predicted that the high oral bioavailability for these compounds in multiple species should translate into lower intra- and intersubject variability in man. The long plasma half-life of the lead is consistent with once or twice daily administration for chronic therapy. Analogue 22 (CT51464) thus appears to be a promising oral GPIIb-IIIa inhibitor with significantly improved pharmacokinetic properties over the previously described clinical candidates and may be found useful in the treatment of arterial occlusive disorders.
Collapse
Affiliation(s)
- Mukund M Mehrotra
- Millennium Pharmaceuticals Inc., 256 E. Grand Avenue, South San Francisco, CA 94080, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Chakrabarti S, Clutton P, Varghese S, Cox D, Mascelli MA, Freedman JE. Glycoprotein IIb/IIIa inhibition enhances platelet nitric oxide release. Thromb Res 2004; 113:225-33. [PMID: 15140587 DOI: 10.1016/j.thromres.2004.02.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2003] [Revised: 02/24/2004] [Accepted: 02/24/2004] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Platelet aggregates form by fibrinogen binding to the membrane receptor glycoprotein IIb/IIIa (GPIIb/IIIa). While GPIIb/IIIa inhibitors block fibrinogen-platelet binding, stimulation of other functionally important platelet receptors may still occur. Blocking the GPIIb/IIIa receptor prevents platelet aggregation but not activation and the subsequent effect on other platelet pathways is largely unknown. MATERIALS AND METHODS As activated platelets release reactive oxygen species that may influence thrombosis or vascular function, the effect of GPIIb/IIIa inhibitors on the platelet release of nitric oxide (NO) and superoxide was determined using an electrochemical detector and luminescence, respectively. Location of relevant platelet proteins and the interaction between platelets and leukocytes in the presence or absence of GPIIb/IIIa inhibition was determined. RESULTS Although incubation with GPIIb/IIIa inhibitors completely abolished platelet aggregation, stimulation dependent NO release was significantly enhanced. Superoxide is known to alter the bioavailability of NO, and its contribution to the GPIIb/IIIa dependent increase in NO release was determined. In the presence of GPIIb/IIIa inhibitors, platelet superoxide release was significantly decreased. Preincubation with GPIIb/IIIa inhibitors also modified aggregation induced membrane translocation of the platelet proteins, endothelial NO synthase (eNOS) and NADPH oxidase (p67phox and p47phox), known to contribute to the generation of NO and superoxide, respectively. In the presence of leukocytes, abciximab incubation led to enhanced NO release and attenuated superoxide generation. CONCLUSION These observations suggest that the pharmacological effects of GPIIb/IIIa antagonists on platelet function, apart from inhibition of aggregation, may contribute to their efficacy.
Collapse
Affiliation(s)
- Subrata Chakrabarti
- Whitaker Cardiovascular Institute and Evans Department of Medicine, Boston University School of Medicine, 715 Albany Street, W507, Boston, MA 02481, USA
| | | | | | | | | | | |
Collapse
|
18
|
Seyfarth HJ, Koksch M. Fibrinogen receptor antagonists induce conformational changes of the human platelet glycoprotein IIb. ACTA ACUST UNITED AC 2004; 62:14-24. [PMID: 15476209 DOI: 10.1002/cyto.b.20026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Controversial results have been reported concerning the ability of fibrinogen receptor antagonists (fibans) to induce conformational changes in the fibrinogen receptor after binding to it as the initial step of fibrinogen binding and platelet activation. METHODS Platelets in citrated whole blood were stained with several pairs of anti-glycoprotein (anti-GP) IIb-directed monoclonal antibodies conjugated to phycoerythrin (PE) or indirectly labeled with Cy5. Pairs of monoclonal antibodies that induced a high-fluorescence resonance energy transfer (FRET) efficiency served as tools to detect activation-dependent changes of GP IIb after addition of adenosine diphosphate and several fibans. RESULTS Using the combination of the clones 5B12-PE and P2-biotin/SA-Cy5, a concentration-dependent alteration of the GP IIb conformation was observed after addition of tirofiban, eptifibatide, and lotrafiban. Magnitude and kinetics differed among the investigated substances. CONCLUSION The newly developed FRET assay allows the direct investigation of conformational changes of GP IIb after addition of platelet agonists or receptor ligands, as shown for three fibans.
Collapse
|
19
|
Shimaoka M, Salas A, Yang W, Weitz-Schmidt G, Springer TA. Small molecule integrin antagonists that bind to the beta2 subunit I-like domain and activate signals in one direction and block them in the other. Immunity 2003; 19:391-402. [PMID: 14499114 DOI: 10.1016/s1074-7613(03)00238-3] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Leukocyte integrins contain an inserted (I) domain in their alpha subunits and an I-like domain in their beta(2) subunit, which directly bind ligand and regulate ligand binding, respectively. We describe a novel mechanistic class of integrin inhibitors that bind to the metal ion-dependent adhesion site of the beta(2) I-like domain and prevent its interaction with and activation of the alpha(L) I domain. The inhibitors do not bind to the alpha(L) I domain but stabilize alpha/beta subunit association and can show selectivity for alpha(L)beta(2) compared to alpha(M)beta(2). The inhibitors reveal a crucial intersection for relaying conformational signals within integrin extracellular domains. While blocking signals in one direction to the I domain, the antagonists induce the active conformation of the I-like domain and stalk domains, and thus transmit conformational signals in the other direction toward the transmembrane domains.
Collapse
Affiliation(s)
- Motomu Shimaoka
- The CBR Institute for Biomedical Research, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
| | | | | | | | | |
Collapse
|
20
|
Hynes RO, Lively JC, McCarty JH, Taverna D, Francis SE, Hodivala-Dilke K, Xiao Q. The diverse roles of integrins and their ligands in angiogenesis. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 67:143-53. [PMID: 12858535 DOI: 10.1101/sqb.2002.67.143] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- R O Hynes
- Howard Hughes Medical Institute, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | | | | | | | | | | | |
Collapse
|
21
|
Shimaoka M, Springer TA. Therapeutic antagonists and conformational regulation of integrin function. Nat Rev Drug Discov 2003; 2:703-16. [PMID: 12951577 DOI: 10.1038/nrd1174] [Citation(s) in RCA: 248] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Integrins are a structurally elaborate family of adhesion molecules that transmit signals bi-directionally across the plasma membrane by undergoing large-scale structural rearrangements. By regulating cell-cell and cell-matrix contacts, integrins participate in a wide range of biological processes, including development, tissue repair, angiogenesis, inflammation and haemostasis. From a therapeutic standpoint, integrins are probably the most important class of cell-adhesion receptors. Recent progress in the development of integrin antagonists has resulted in their clinical application and has shed new light on integrin biology. On the basis of their mechanism of action, small-molecule integrin antagonists fall into three different classes. Each of these classes affect the equilibria that relate integrin conformational states, but in different ways.
Collapse
Affiliation(s)
- Motomu Shimaoka
- The Center for Blood Research, Department of Anesthesia and Pathology, Harvard Medical School, 200 Longwood, Boston, Massachussets 02115, USA
| | | |
Collapse
|
22
|
Abstract
Pharmacological agents directed against the integrins alpha(v)beta(3) and alpha(v)beta(5) have been reported to inhibit angiogenesis. However, genetic ablations of the genes encoding these integrins fail to block angiogenesis and in some cases even enhance it. This apparent paradox suggests the hypotheses that these integrins are negative regulators of angiogenesis and that the drugs targeting them may be acting as agonists rather than antagonists.
Collapse
Affiliation(s)
- Richard O Hynes
- Howard Hughes Medical Institute and Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
| |
Collapse
|