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Bargeron Clark K, Hsiao HM, Noisakran S, Tsai JJ, Perng GC. Role of microparticles in dengue virus infection and its impact on medical intervention strategies. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2012; 85:3-18. [PMID: 22461739 PMCID: PMC3313537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Dengue virus (DV) is one of the most important vector-borne diseases in the world. It causes a disease that manifests as a spectrum of clinical symptoms, including dengue hemorrhagic fever. DV is proficient at diverting the immune system to facilitate transmission through its vector host, Aedes spp. mosquito. Similar to other vector-borne parasites, dengue may also require a second structural form, a virus of alternative morphology (VAM), to complete its life cycle. DV can replicate to high copy numbers in patient plasma, but no classical viral particles can be detected by ultra-structural microscopy analysis. A VAM appearing as a microparticle has been recapitulated with in vitro cell lines Meg01 and K562, close relatives to the cells harboring dengue virus in vivo. VAMs are likely to contribute to the high viremia levels observed in dengue patients. This review discusses the possible existence of a VAM in the DV life cycle.
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Affiliation(s)
- Kristina Bargeron Clark
- Department of Pathology and Laboratory Medicine, Emory
Vaccine Center, Emory University School of Medicine, Atlanta, Georgia
| | - Hui-Mien Hsiao
- Department of Pathology and Laboratory Medicine, Emory
Vaccine Center, Emory University School of Medicine, Atlanta, Georgia
| | - Sansanee Noisakran
- Department of Pathology and Laboratory Medicine, Emory
Vaccine Center, Emory University School of Medicine, Atlanta, Georgia
- Medical Biotechnology Unit, National Center for Genetic
Engineering and Biotechnology, National Science and Technology Development
Agency, Pathumthani 12120, Thailand
| | - Jih-Jin Tsai
- Tropical Medicine Center, Department of Internal
Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
- Division of Infectious Diseases, Department of Internal
Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
- College of Medicine, Faculty of Medicine, Kaohsiung
Medical University, Kaohsiung, Taiwan
| | - Guey Chuen Perng
- Department of Pathology and Laboratory Medicine, Emory
Vaccine Center, Emory University School of Medicine, Atlanta, Georgia
- Department of Microbiology and Immunology, National
Cheng Kung University Medical College, Tainan, Taiwan
- Center of Infectious Diseases and Signaling Research,
National Cheng Kung University Medical College, Tainan, Taiwan
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102
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Schwertz H, Rowley JW, Tolley ND, Campbell RA, Weyrich AS. Assessing protein synthesis by platelets. Methods Mol Biol 2012; 788:141-153. [PMID: 22130706 DOI: 10.1007/978-1-61779-307-3_11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Platelets are anucleate cytoplasts that circulate in the bloodstream for approximately 9-11 days. Because they lack nuclei, platelets were considered incapable of protein synthesis. However, studies over the last decade have revealed that platelets use a variety of translational control pathways to synthesize proteins.A variety of protocols can be employed to assess protein synthesis by platelets. These protocols are scattered throughout the literature and, more often than not, lack critical details. In this chapter, we thoroughly outline methods used in our laboratory to assess protein synthesis by platelets.
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Affiliation(s)
- Hansjörg Schwertz
- Program in Molecular Medicine, Department of Surgery, University of Utah, Salt Lake City, UT, USA
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103
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Kraemer BF, Campbell RA, Schwertz H, Cody MJ, Franks Z, Tolley ND, Kahr WHA, Lindemann S, Seizer P, Yost CC, Zimmerman GA, Weyrich AS. Novel anti-bacterial activities of β-defensin 1 in human platelets: suppression of pathogen growth and signaling of neutrophil extracellular trap formation. PLoS Pathog 2011; 7:e1002355. [PMID: 22102811 PMCID: PMC3213094 DOI: 10.1371/journal.ppat.1002355] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/20/2011] [Indexed: 12/11/2022] Open
Abstract
Human β-defensins (hBD) are antimicrobial peptides that curb microbial activity. Although hBD's are primarily expressed by epithelial cells, we show that human platelets express hBD-1 that has both predicted and novel antibacterial activities. We observed that activated platelets surround Staphylococcus aureus (S. aureus), forcing the pathogens into clusters that have a reduced growth rate compared to S. aureus alone. Given the microbicidal activity of β-defensins, we determined whether hBD family members were present in platelets and found mRNA and protein for hBD-1. We also established that hBD-1 protein resided in extragranular cytoplasmic compartments of platelets. Consistent with this localization pattern, agonists that elicit granular secretion by platelets did not readily induce hBD-1 release. Nevertheless, platelets released hBD-1 when they were stimulated by α-toxin, a S. aureus product that permeabilizes target cells. Platelet-derived hBD-1 significantly impaired the growth of clinical strains of S. aureus. hBD-1 also induced robust neutrophil extracellular trap (NET) formation by target polymorphonuclear leukocytes (PMNs), which is a novel antimicrobial function of β-defensins that was not previously identified. Taken together, these data demonstrate that hBD-1 is a previously-unrecognized component of platelets that displays classic antimicrobial activity and, in addition, signals PMNs to extrude DNA lattices that capture and kill bacteria. Platelets are small cells in the bloodstream whose primary function is to stop bleeding. In addition to their clotting functions, we show that human platelets stall bacterial growth. This inhibitory property of platelets is due to β-defensin 1, a small antimicrobial protein that kills bacteria. β-defensin 1 also induces white blood cells to discharge spider-like webs that trap and kill bacteria. Together, these findings indicate that human platelets use β-defensin 1 to fight off bacterial infection.
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Affiliation(s)
- Bjoern F. Kraemer
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, United States of America
- Medizinische Klinik III, Universitaetsklinikum Tuebingen, Tuebingen, Germany
| | - Robert A. Campbell
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, United States of America
| | - Hansjörg Schwertz
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, United States of America
- Department of Surgery, University of Utah, Salt Lake City, Utah, United States of America
| | - Mark J. Cody
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, United States of America
| | - Zechariah Franks
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, United States of America
| | - Neal D. Tolley
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, United States of America
| | - Walter H. A. Kahr
- Division of Haematology/Oncology, Program in Cell Biology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Ontario, Canada
| | | | - Peter Seizer
- Medizinische Klinik III, Universitaetsklinikum Tuebingen, Tuebingen, Germany
| | - Christian C. Yost
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, United States of America
- Department of Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Guy A. Zimmerman
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States of America
| | - Andrew S. Weyrich
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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104
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Abstract
For many years, programmed cell death, known as apoptosis, was attributed exclusively to nucleated cells. Currently, however, apoptosis is also well-documented in anucleate platelets. This review describes extrinsic and intrinsic pathways of apoptosis in nucleated cells and in platelets, platelet apoptosis induced by multiple chemical stimuli and shear stresses, markers of platelet apoptosis, mitochodrial control of platelet apoptosis, and apoptosis mediated by platelet surface receptors PAR-1, GPIIbIIIa and GPIbα. In addition, this review presents data on platelet apoptosis provoked by aging of platelets in vitro during platelet storage, platelet apoptosis in pathological settings in humans and animal models, and inhibition of platelet apoptosis by cyclosporin A, intravenous immunoglobulin and GPIIbIIIa antagonist drugs.
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Affiliation(s)
- Valery Leytin
- Division of Transfusion Medicine, Department of Laboratory Medicine, The Keenan Research Centre in the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, ON, Canada.
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105
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Vieira-de-Abreu A, Campbell RA, Weyrich AS, Zimmerman GA. Platelets: versatile effector cells in hemostasis, inflammation, and the immune continuum. Semin Immunopathol 2011; 34:5-30. [PMID: 21818701 DOI: 10.1007/s00281-011-0286-4] [Citation(s) in RCA: 217] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 07/20/2011] [Indexed: 12/28/2022]
Abstract
Platelets are chief effector cells in hemostasis. In addition, however, their specializations include activities and intercellular interactions that make them key effectors in inflammation and in the continuum of innate and adaptive immunity. This review focuses on the immune features of human platelets and platelets from experimental animals and on interactions between inflammatory, immune, and hemostatic activities of these anucleate but complex and versatile cells. The experimental findings and evidence for physiologic immune functions include previously unrecognized biologic characteristics of platelets and are paralleled by new evidence for unique roles of platelets in inflammatory, immune, and thrombotic diseases.
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Affiliation(s)
- Adriana Vieira-de-Abreu
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
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106
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Alfarouk KO, Shayoub ME, Muddathir AK, Elhassan GO, Bashir AH. Evolution of Tumor Metabolism might Reflect Carcinogenesis as a Reverse Evolution process (Dismantling of Multicellularity). Cancers (Basel) 2011; 3:3002-17. [PMID: 24310356 PMCID: PMC3759183 DOI: 10.3390/cancers3033002] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/18/2011] [Accepted: 07/20/2011] [Indexed: 01/14/2023] Open
Abstract
Carcinogenesis occurs through a series of steps from normal into benign and finally malignant phenotype. This cancer evolutionary trajectory has been accompanied by similar metabolic transformation from normal metabolism into Pasteur and/or Crabtree-Effects into Warburg-Effect and finally Cannibalism and/or Lactate-Symbiosis. Due to lactate production as an end-product of glycolysis, tumor colonies acquire new phenotypes that rely on lactate as energetic fuel. Presence of Warburg-Effect indicates that some tumor cells undergo partial (if not complete) de-endosymbiosis and so cancer cells have been become unicellular microorganism (anti-Dollo's Law) specially when they evolve to develop cannibalism as way of metabolism while oxidative types of cells that rely on lactate, as their energetic fuel, might represent extra-endosymbiosis. Thus, at the end, the cancer colony could be considered as integrated metabolic ecosystem. Proper understanding of tumor metabolism will contribute to discover potential anticancer agents besides conventional chemotherapy.
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Affiliation(s)
- Khalid O. Alfarouk
- Department of Evolution of Tumor Metabolism and Pharmacology, Hala Alfarouk Cancer Center, Khartoum 11123, Sudan; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +249-120661220
| | - Mohammed E.A. Shayoub
- Department of Pharmaceutics, Faculty of Pharmacy, University of Khartoum, Khartoum 11111, Sudan; E-Mail:
| | - Abdel Khalig Muddathir
- Department of Pharmacognosy, Faculty of Pharmacy, University of Khartoum, Khartoum 11111, Sudan; E-Mail:
| | - Gamal O. Elhassan
- General Directorate of Pharmacy, Federal Ministry of Health, Khartoum 11111, Sudan; E-Mail:
| | - Adil H.H. Bashir
- Department of Evolution of Tumor Metabolism and Pharmacology, Hala Alfarouk Cancer Center, Khartoum 11123, Sudan; E-Mail:
- Al Jawda Medical Hospital, Khartoum 11111, Sudan
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107
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108
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Garraud O, Damien P, Berthet J, Arthaud CA, Hamzeh-Cognasse H, Cognasse F. [Blood platelets and biological response to 'danger' signals and subsequent inflammation: towards a new paradigm?]. Transfus Clin Biol 2011; 18:165-73. [PMID: 21444230 DOI: 10.1016/j.tracli.2011.02.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 02/12/2011] [Indexed: 12/22/2022]
Abstract
Blood platelets are cellular elements of primary haemostasis. During the last decade research on platelets has been subsequently based on this paradigm, with separate observations on issues such as the ability for platelets to bind infectious agents or even engulf them, to drop in counts in case of evolving infectious processes, etc. More recently, novel work has set up bases for novel functions for platelets, as members of functional immune cells, principally in innate immunity but capable of influencing adaptive immunity. Platelets are thus essential to haemostasis and to inflammation, questioning their essential functionality and the set up of a novel paradigm: could platelets be tissue-repairing cells? Such an assumption would open an entire new field of investigations. The present "State of the Art" essay attempts to discuss the main arguments on this.
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Affiliation(s)
- O Garraud
- EFS Auvergne-Loire Saint-Étienne, 25, boulevard Pasteur, 42023 Saint-Étienne cedex 2, France.
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109
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Osei-Bimpong A, Saleh M, Sola-Visner M, Widness J, Veng-Pedersen P. Correction for effect of cold storage on immature platelet fraction. J Clin Lab Anal 2011; 24:431-3. [PMID: 21089177 DOI: 10.1002/jcla.20426] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
It is common practice to store samples and measure the immature platelet fraction (IPF) only when the initial standard complete blood count and the blood smear indicate thrombocytopenia. However, the cold storage introduces an inherent error in the %IPF. A falsely elevated %IPF carries the risk of potentially misleading the clinicians' interpretation of the thrombopoietic activity, thus hindering the clinical utility of this parameter. To address this issue, we determined the IPF% in individual blood samples from 29 adults at 0, 4, 8, 10, 12, 21, and 24 hr after the blood draw. This study demonstrated that the effect of 4°C storage is linear over a 24 hr period and independent of the initial IPF%. These observations have enabled the development of a proposed algorithm for a corrected IPF%, which is equal to the uncorrected IPF% minus 1.34 times the length of time in hours of storage at 4°C. The proposed correction algorithm extends the utility of this clinically important laboratory parameter. However, care should be taken not to extrapolate the algorithm significantly beyond 24 hr storage, because the experimental data only covered this range.
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Affiliation(s)
- Andrew Osei-Bimpong
- Department of Haematology, Imperial College Healthcare Trust, United Kingdom
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110
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Schubert S, Schwertz H, Weyrich AS, Franks ZG, Lindemann S, Otto M, Behr H, Loppnow H, Schlitt A, Russ M, Presek P, Werdan K, Buerke M. Staphylococcus aureus α-toxin triggers the synthesis of B-cell lymphoma 3 by human platelets. Toxins (Basel) 2011; 3:120-33. [PMID: 22069700 PMCID: PMC3202813 DOI: 10.3390/toxins3020120] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 01/22/2011] [Accepted: 01/25/2011] [Indexed: 01/20/2023] Open
Abstract
The frequency and severity of bacteremic infections has increased over the last decade and bacterial endovascular infections (i.e., sepsis or endocarditis) are associated with high morbidity and mortality. Bacteria or secreted bacterial products modulate platelet function and, as a result, affect platelet accumulation at sites of vascular infection and inflammation. However, whether bacterial products regulate synthetic events in platelets is not known. In the present study, we determined if prolonged contact with staphylococcal α-toxin signals platelets to synthesize B-cell lymphoma (Bcl-3), a protein that regulates clot retraction in murine and human platelets. We show that α-toxin induced α(IIb)β(3)-dependent aggregation (EC(50) 2.98 µg/mL ± 0.64 µg/mL) and, over time, significantly altered platelet morphology and stimulated de novo accumulation of Bcl-3 protein in platelets. Adherence to collagen or fibrinogen also increased the expression of Bcl-3 protein by platelets. α-toxin altered Bcl-3 protein expression patterns in platelets adherent to collagen, but not fibrinogen. Pretreatment of platelets with inhibitors of protein synthesis or the mammalian Target of Rapamycin (mTOR) decreased Bcl-3 protein expression in α-toxin stimulated platelets. In conclusion, Staphylococcusaureus-derived α-toxin, a pore forming exotoxin, exerts immediate (i.e., aggregation) and prolonged (i.e., protein synthesis) responses in platelets, which may contribute to increased thrombotic events associated with gram-positive sepsis or endocarditis.
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Affiliation(s)
- Sebastian Schubert
- Department of Medicine III, Martin Luther University, Halle, Saale, Germany; (S.S.); (M.O.); (H.B.); (H.L.); (A.S.); (M.R.); (K.W.)
| | - Hansjörg Schwertz
- Program in Molecular Medicine, University of Utah, Salt Lake City, UT 84112, USA; (H.S.); (A.S.W.); (Z.G.F.)
| | - Andrew S. Weyrich
- Program in Molecular Medicine, University of Utah, Salt Lake City, UT 84112, USA; (H.S.); (A.S.W.); (Z.G.F.)
| | - Zechariah G. Franks
- Program in Molecular Medicine, University of Utah, Salt Lake City, UT 84112, USA; (H.S.); (A.S.W.); (Z.G.F.)
| | - Stephan Lindemann
- Department of Medicine III, Eberhard Karls University, Tübingen, Germany;
| | - Monika Otto
- Department of Medicine III, Martin Luther University, Halle, Saale, Germany; (S.S.); (M.O.); (H.B.); (H.L.); (A.S.); (M.R.); (K.W.)
| | - Hagen Behr
- Department of Medicine III, Martin Luther University, Halle, Saale, Germany; (S.S.); (M.O.); (H.B.); (H.L.); (A.S.); (M.R.); (K.W.)
| | - Harald Loppnow
- Department of Medicine III, Martin Luther University, Halle, Saale, Germany; (S.S.); (M.O.); (H.B.); (H.L.); (A.S.); (M.R.); (K.W.)
| | - Axel Schlitt
- Department of Medicine III, Martin Luther University, Halle, Saale, Germany; (S.S.); (M.O.); (H.B.); (H.L.); (A.S.); (M.R.); (K.W.)
| | - Martin Russ
- Department of Medicine III, Martin Luther University, Halle, Saale, Germany; (S.S.); (M.O.); (H.B.); (H.L.); (A.S.); (M.R.); (K.W.)
| | - Peter Presek
- Clinical Pharmacology, Martin Luther University, Halle, Saale, Germany;
| | - Karl Werdan
- Department of Medicine III, Martin Luther University, Halle, Saale, Germany; (S.S.); (M.O.); (H.B.); (H.L.); (A.S.); (M.R.); (K.W.)
| | - Michael Buerke
- Department of Medicine III, Martin Luther University, Halle, Saale, Germany; (S.S.); (M.O.); (H.B.); (H.L.); (A.S.); (M.R.); (K.W.)
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111
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Thon JN, Montalvo A, Patel-Hett S, Devine MT, Richardson JL, Ehrlicher A, Larson MK, Hoffmeister K, Hartwig JH, Italiano JE. Cytoskeletal mechanics of proplatelet maturation and platelet release. ACTA ACUST UNITED AC 2011; 191:861-74. [PMID: 21079248 PMCID: PMC2983072 DOI: 10.1083/jcb.201006102] [Citation(s) in RCA: 198] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Megakaryocytes generate platelets by remodeling their cytoplasm into long proplatelet extensions, which serve as assembly lines for platelet production. Although the mechanics of proplatelet elongation have been studied, the terminal steps of proplatelet maturation and platelet release remain poorly understood. To elucidate this process, released proplatelets were isolated, and their conversion into individual platelets was assessed. This enabled us to (a) define and quantify the different stages in platelet maturation, (b) identify a new intermediate stage in platelet production, the preplatelet, (c) delineate the cytoskeletal mechanics involved in preplatelet/proplatelet interconversion, and (d) model proplatelet fission and platelet release. Preplatelets are anucleate discoid particles 2-10 µm across that have the capacity to convert reversibly into elongated proplatelets by twisting microtubule-based forces that can be visualized in proplatelets expressing GFP-β1-tubulin. The release of platelets from the ends of proplatelets occurs at an increasing rate in time during culture, as larger proplatelets undergo successive fission, and is potentiated by shear.
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Affiliation(s)
- Jonathan N Thon
- Translational Medicine Division, Brigham and Women's Hospital, Boston, MA 02115, USA
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112
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Abstract
In this issue, Thon et al. (2010. J. Cell Biol. doi: 10.1083/jcb.201006102) demonstrate that newly released platelets exhibit bipolar behavior, shifting back and forth between round cells and multibodied proplatelets (Thon et al., 2010). The authors define this intermediate as a preplatelet and, in doing so, shed new insight into the terminal steps of platelet maturation.
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Affiliation(s)
- Hansjörg Schwertz
- Program in Molecular Medicine, University of Utah, Salt Lake City, UT 84112, USA
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113
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Devine DV, Schubert P. Proteomic applications in blood transfusion: working the jigsaw puzzle. Vox Sang 2010; 100:84-91. [DOI: 10.1111/j.1423-0410.2010.01433.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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114
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Smith TL, Weyrich AS. Platelets as central mediators of systemic inflammatory responses. Thromb Res 2010; 127:391-4. [PMID: 21074247 DOI: 10.1016/j.thromres.2010.10.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 10/15/2010] [Accepted: 10/17/2010] [Indexed: 12/31/2022]
Abstract
Systemic inflammatory responses are associated with high morbidity and mortality and represent a diverse and clinically challenging group of diseases. Platelets are increasingly linked to inflammation, in addition to their well-known roles in hemostasis and thrombosis. There is agreement that traditional functions of platelets, including adherence, aggregation, and secretion of preformed mediators, contribute to systemic inflammatory responses. However, emerging evidence indicates that platelets function in non-traditional ways. In this review, we focus on new functions of platelets that may be involved in the host response to infection.
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Affiliation(s)
- Tammy L Smith
- Program in Molecular Medicine, University of Utah, Salt Lake City, Utah 84112, USA
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115
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Leavitt AD. Are there more tricks in the bag for treating thrombocytopenia? J Clin Invest 2010; 120:3807-10. [PMID: 20972327 DOI: 10.1172/jci45179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Thrombocytopenia, an abnormally low number of circulating platelets, results from inadequate platelet production, splenic platelet sequestration, or accelerated platelet clearance. Platelet transfusions are now the cornerstone for treating thrombocytopenia. With an ever-expanding demand for platelets, and with many patients having an inadequate response to platelet transfusions, new strategies are needed to treat thrombocytopenia. In this issue of the JCI, Fuentes et al. present provocative data regarding the use of direct megakaryocyte infusions as a novel approach to manage this vexing clinical problem.
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Affiliation(s)
- Andrew D Leavitt
- Department of Laboratory Medicine, University of California, San Francisco, San Francisco, California 94143-0100, USA.
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116
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Hermann M, Nussbaumer O, Knöfler R, Hengster P, Nussbaumer W, Streif W. Real-Time Live Confocal Fluorescence Microscopy as a New Tool for Assessing Platelet Vitality. Transfus Med Hemother 2010; 37:299-305. [PMID: 21113254 DOI: 10.1159/000320368] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 08/20/2010] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND: Assessment of platelet vitality is important for patients presenting with inherited or acquired disorders of platelet function and for quality assessment of platelet concentrates. METHODS: Herein we combined live stains with intra-vital confocal fluorescence microscopy in order to obtain an imaging method that allows fast and accurate assessment of platelet vitality. Three fluorescent dyes, FITC-coupled wheat germ agglutinin (WGA), tetramethylrhodamine methyl ester perchlorate (TMRM) and acetoxymethylester (Rhod-2), were used to assess platelet morphology, mitochondrial activity and intra-platelet calcium levels. Microscopy was performed with a microlens-enhanced Nipkow spinning disk-based system allowing live confocal imaging. RESULTS: Comparison of ten samples of donor platelets collected before apheresis and platelets collected on days 5 and 7 of storage showed an increase in the percentage of Rhod-2-positive platelets from 3.6 to 47 and finally to 71%. Mitochondrial potential was demonstrated in 95.4% of donor platelets and in 92.5% of platelets stored for 7 days. CONCLUSION: Such fast and accurate visualization of known key parameters of platelet function could be of relevance for studies addressing the quality of platelets after storage and additional manipulation, such as pathogen inactivation, as well as for the analysis of inherited platelet function disorders.
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Affiliation(s)
- Martin Hermann
- KMT Laboratory, Department of Visceral, Transplant and Thoracic Surgery, Center for Operative Medicine, Innsbruck, Austria
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117
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118
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Abstract
Dengue has been recognized as one of the most important vector-borne emerging infectious diseases globally. Though dengue normally causes a self-limiting infection, some patients may develop a life-threatening illness, dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). The reason why DHF/DSS occurs in certain individuals is unclear. Studies in the endemic regions suggest that the preexisting antibodies are a risk factor for DHF/DSS. Viremia and thrombocytopenia are the key clinical features of dengue virus infection in patients. The amounts of virus circulating in patients are highly correlated with severe dengue disease, DHF/DSS. Also, the disturbance, mainly a transient depression, of hematological cells is a critical clinical finding in acute dengue patients. However, the cells responsible for the dengue viremia are unresolved in spite of the intensive efforts been made. Dengue virus appears to replicate and proliferate in many adapted cell lines, but these in vitro properties are extremely difficult to be reproduced in primary cells or in vivo. This paper summarizes reports on the permissive cells in vitro and in vivo and suggests a hematological cell lineage for dengue virus infection in vivo, with the hope that a new focus will shed light on further understanding of the complexities of dengue disease.
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119
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Ohi R. Kip3-ing kinetochores clustered. Cell Cycle 2010; 9:2497. [PMID: 20647749 DOI: 10.4161/cc.9.13.12274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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120
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Abstract
The cellular and molecular mechanisms orchestrating the complex process by which bone marrow megakaryocytes form and release platelets remain poorly understood. Mature megakaryocytes generate long cytoplasmic extensions, proplatelets, which have the capacity to generate platelets. Although microtubules are the main structural component of proplatelets and microtubule sliding is known to drive proplatelet elongation, the role of actin dynamics in the process of platelet formation has remained elusive. Here, we tailored a mouse model lacking all ADF/n-cofilin-mediated actin dynamics in megakaryocytes to specifically elucidate the role of actin filament turnover in platelet formation. We demonstrate, for the first time, that in vivo actin filament turnover plays a critical role in the late stages of platelet formation from megakaryocytes and the proper sizing of platelets in the periphery. Our results provide the genetic proof that platelet production from megakaryocytes strictly requires dynamic changes in the actin cytoskeleton.
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121
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