Platelets and cytokines: How and why?

Disponible en ligne sur

www.sciencedirect.com Transfusion Clinique et Biologique 19 (2012) 104–108

Review article

Platelets and cytokines: How and why?夽 Plaquettes et cytokines : comment et pourquoi ? O. Garraud a,b,c,∗ , H. Hamzeh-Cognasse b,c , F. Cognasse a,c a

Établissement fran¸cais du sang Auvergne-Loire, 25, boulevard Pasteur, 42023 Saint-Étienne cedex 02, France b EA3064, Faculty of Medicine, University of Lyon, 42023 Saint-Étienne cedex 02, France c IFR 143, IFRESIS, University of Lyon 3, 42023 Saint-Étienne cedex 02, France Available online 7 June 2012

Abstract For patients with platelet deficiencies, platelet components are therapeutic products for which there is no substitute. However, transfusion complications are more frequent with this labile blood product than with others. This is attributable to products secreted by the platelets themselves, including a variety of cytokines, chemokines, and biological response modifiers, some of which are secreted in large quantities following platelet activation. Why platelets are activated and prone to releasing these molecules during certain inflammatory and innate immune responses is not yet fully understood, but it could be due to several parameters including incompatibilities between blood donors and recipients, the process of platelet preparation and preservation, and the ability of the donor’s immune system to sense danger presented by external stimuli during the blood donation process. This review presents our current knowledge of how the platelets that constitute the platelet component for transfusion are sources of cytokines and biological response modifiers and discusses methods to improve the quality of blood transfusion products and safety for patients. © 2012 Elsevier Masson SAS. All rights reserved. Keywords: Platelets; Transfusion; Transfusion hazards; Inflammation; Innate immunity; Cytokines; CD40L; Biological response modifiers

Résumé Pour les patients atteints de déficiences plaquettaires, les composants plaquettaires sont des produits thérapeutiques pour lesquelles il n’existe pas de substitut. Cependant, les complications transfusionnelles sont plus fréquentes avec ce produit sanguin labile. Cela est dû aux produits secrétés par les plaquettes elles-mêmes, notamment divers cytokines, chimiokines et modificateurs de réponse biologique, dont certains sont sécrétés en grande quantité après activation plaquettaire. Les raisons pour lesquelles les plaquettes sont activées et libèrent ces molécules au cours de certaines réponses inflammatoires et immunitaires innées ne sont pas encore entièrement comprises, mais elles pourraient être dues à plusieurs paramètres, y compris les incompatibilités entre les donneurs et les receveurs, le processus de préparation et de préservation des plaquettes et la capacité du système immunitaire du donneur à sentir un danger présenté par des stimuli externes au cours du processus du don de sang. Cette revue présente les connaissances actuelles sur les plaquettes en tant que sources de cytokines et de modificateurs de réponse biologique au cours de la transfusion et discute les méthodes pour améliorer la qualité des produits de transfusion sanguine et leur sécurité pour les patients. © 2012 Elsevier Masson SAS. Tous droits réservés. Mots clés : Plaquettes ; Transfusion ; Effets indésirables transfusionnels ; Inflammation ; Immunité innée ; Cytokines ; CD40L ; Modificateurs du comportement biologique

1. Introduction Blood platelets are anucleate cell fragments that are essential to primary haemostasis [1]. They patrol the 100,000 km long vascular system and repair injured epithelial tissue by initiating 夽 This article was presented at the symposium “Host and blood products: an inflamed relationship”, La Plaine-Saint-Denis, France, 5th December 2011. ∗ Corresponding author. E-mail address: [email protected] (O. Garraud).

1246-7820/$ – see front matter © 2012 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.tracli.2012.02.004

clotting (primary haemostasis) [2]. Under normal physiological conditions, this process requires approximately 15–20 g/l of platelets per day, which are produced by bone marrow-derived megakaryocytes [3]. Under pathological conditions, the need for platelets may greatly exceed this baseline level. When production is insufficient for constitutive production or excessive peripheral consumption (or destruction), platelet component transfusions may be needed; these can be either therapeutic or prophylactic. At this time, there are no suitable alternatives to platelet component transfusions. Platelet component

O. Garraud et al. / Transfusion Clinique et Biologique 19 (2012) 104–108

transfusions are safe and effective (except for some refractory post-immunization cases) provided they are performed appropriately [4–6]. 2. Clinical observations regarding platelet component transfusions and the immune response Although platelet component transfusions are now quite safe, some decades prior, they were almost always associated with discomfort and side effects such as chills, fever, and rigor. This is attributed to leukocyte-derived inflammatory products prior to systematic leukoreduction [7,8]. However, even with recent improvements, platelet component transfusions are still associated with more immunological risks than other labile blood products (e.g., red blood cell concentrates and fresh-frozen plasma): 527.9/100,000 platelet component units were associated with complications. Of these, 70.8/100,000 units were associated with acute nonhaemolytic febrile transfusion reactions, 280.1/100,000 units with allergic reactions, 4.3/100,000 units with transfusion-related acute lung injury (TRALI), and 2.9/100,000 units with bacterial infection [9]. Two of those complications were found to be associated with soluble CD40 ligand (sCD40L, also called sCD154), an immunomodulatory factor that is largely produced by platelets and targets several types of reactive cells [10–13]. These findings indicate that platelets themselves may contribute, through their secreted products, to “immunological acute transfusion reactions” [14,15]. This somewhat controversial issue poses considerable clinical challenges and has stimulated extensive research both in clinical situations and in animal models.

105

• direct secretion from ␣-granules to the external environment through the open canalicular system; • from the granules to the membrane; • and subsequently from the membrane to the external environment after splicing into a soluble form and shedding from the membrane [16,18–20]. Finally, there are three types of platelet molecules of particular interest within the context of platelet component transfusions: • membrane glycoproteins; • glycoproteins that are either docked or secreted; • and proteins of the signalosome, which may be phosphorylated in response to signalling. Altogether, more than 300 glycoproteins have been identified as being associated with platelets in some way, and roles for many more in physiological and pathological processes are being discovered. Indeed, we recently reported that dozens of cytokines, chemokines, and biological response modifiers are bound to receptors on the platelet membrane; some of these molecules are from external sources, while others appear to be recaptures of platelet-secreted cytokines or chemokines [14,16,21–26]. In a recent and elegant study, Fong et al. reported on 1048 proteins constituting the platelet sheddome; molecules such as HLA class I are abundantly expressed (about 100,000 copies per platelet) [27]. ABH antigens are weakly expressed [28] in platelets, and antigens that are characteristic of platelets, such as those in the human platelet antigen (HPA) group, are actually variant amino acid sequences principally within glycoprotein IIb-IIIa (the common isoform is “a”, while the rarer form is “b”) [29].

3. Origin of molecules associated with platelets There are three main categories of platelet-associated molecules: • those absorbed from the external environment (mainly plasma); • those inherited from the megakaryocyte lineage/progeny; • and de novo synthesized molecules (those sources of glycoproteins remain hypothetical, since only mRNAs have been reported so far, not the secreted glycoproteins) [1,7,8,16,17]. There are also three main locations for platelet-associated molecules: • the platelet membrane; • ␣-granules, which contain most cytokines and chemokines along with haemostatic factors; • and dense (␦) granules (containing adenosine monophosphate [AMP], adenosine triphosphate [ATP], Ca++ , serotonin, etc.). In addition, there are three ways in which platelets may act as the source of proteins and glycoproteins:

4. Consequences of lesions and alterations in ex vivo platelets According to a seminal report from Phipps et al., platelets are the source of 95% of sCD40L found in the plasma [10]. This sCD40L is responsible for clinically significant acute transfusion reactions, which led to the question of whether large amounts of proinflammatory factors are secreted by donor platelets and then infused into recipients [13,30–32]. We, and others, obtained evidence that the method by which the platelets that constitute platelet components for transfusion are prepared may create lesions on the platelets and activate them, altering both their procoagulant and proinflammatory properties1 [33]. Collection (e.g., by recovering whole blood buffy coats or by using various apheresis collection systems), separation, preparation, addition of platelet solutions, and storage accelerate the secretion of cytokines, chemokines, and biological response modifiers by platelets and increase, in particular, the secretion of proinflammatory proteins. This led us to question whether platelets can sense mechanical damage and stress conditions. Studies by our group and others 1

Nguyen et al., submitted for publication.

106

O. Garraud et al. / Transfusion Clinique et Biologique 19 (2012) 104–108

revealed that platelets can either carry or harbour infectious pathogens (despite probably not being able to cause infection): indeed, platelets express several types of receptors for viruses (e.g., human immunodeficiency virus [HIV] and hepatitis C virus [HCV]) and bacteria, as well as receptors for immune complexes formed with infectious pathogens (e.g., complement receptors and Fc receptors for immunoglobulin H chains) [7,8,34–37]. We next looked for the expression of other types of pathogen recognition receptors that could sense pathogenassociated molecular patterns or damage (tissue)-associated molecular patterns. We reported on the presence of TLR2, TLR4, and TLR9 on or in human platelets [38], while others later reported the possible expression of TLR1 and TLR6 (in mice and possibly also in humans) [39]. We also found that engagement of TLR2 or TLR4 by the appropriate ligands led to differential secretion specific to the nature of the sensed danger (e.g., for TLR4:LPS, cytokines, chemokines, and biological response modifiers were secreted) [7,37,40–54]. We confirmed the presence of the widely expressed TLR adaptor protein MyD88 and described the presence of the alternate TLR adaptor TRIF on human platelets; we also identified a cascade of proteins that usually constitute the signalosome in nucleated eukaryote cells [43,44,55–57]. Some of those proteins are specifically phosphorylated after TLR2 or TLR4 engagement. The final signal after platelet surface protein engagement is NF␬B, the mRNA for which is significantly upregulated and accumulates in platelets. It should be noted that it is not yet clear whether NF␬B protein is expressed, although it could play a role in damage repair, similar to what this molecule does during embryogenesis2 [58–61]. 5. Clinical relevance of recent findings to transfusion medicine The discovery of sCD40L and its role in acute transfusion reactions, first in nonhaemolytic febrile transfusion reactions and then in TRALI, was intriguing. Thus, we, and others, established ex vivo models of blood cells obtained from healthy donors to explore the extent to which intact or lysed platelets, obtained from platelet components with the aim being transfused, and their supernatants constituted biological response modifiers capable of altering the functions of different types of cells. This was indeed the case for almost all of the cells tested, such as B lymphocytes, T lymphocytes, dendritic cells, monocytes, and epithelial cells [11,13,37,62–72]. The accumulation of inflammatory cytokines and chemokines during platelet component storage increased the inflammatory effects of leukocytes and endothelial cells to supraphysiological levels comparable to those observed under pathological conditions. We provided clear evidence of a role for sCD40L in acute transfusion reaction cases in which there was complete excretion of sCD40L from the platelets into the platelet component supernatant, such that no sCD40L was left within the platelets, in contrast to what we observed in samples from control patients [26,63]. We extended

2

Damien et al., submitted for publication.

this finding to a series of other cytokines that have not as yet been associated with platelets; e.g., IL27 and OX40L3 . We now propose that receptors and/or the ligands of pathogenic sentinel molecules can have polymorphisms that alter mutual affinity, such that certain platelet component transfusions are “at risk” of leading to an acute transfusion reactions in individual patients/recipients (this hypothesis is being explored). Recent evidence also suggests that platelets can be associated with organ or tissue pathologies (e.g., cardiovascular diseases, arthritis, and diabetes); thus, we now question not only whether platelets may harbour sensors for pathogen-associated molecular patterns, but also for damage-associated molecular patterns, and consequently may be able to sense danger in altered tissues (preliminary findings from our current explorations have encouraged us to pursue this research path) [7,15,37]. We are also exploring whether allogeneic transfused platelets may be recognized as “dangerous” by sentinel cells of innate immunity, leading to alloantibody formation, (e.g., with HLA and HPA antigens) and the extent to which platelets themselves may participate in this common pathology because of their dual functions in altering cell function and favouring antigen presentation to T cells by dendritic cells. 6. Conclusions Platelets play roles in physiology that extend well beyond primary haemostasis. They are essential for halting bleeding and for the repair of insulted vessels. For severe clinical conditions, allogeneic platelets donated by a healthy person can be transfused to recipients/patients who require them. This procedure is lifesaving, but it can sometimes lead to transfusion-associated adverse events and unwanted effects, which are more often encountered with platelet components than with other labile blood products. Many of these hazards are due to numerous proinflammatory factors that are secreted by platelets, possibly in response to the preparation process; these factors are not fully counteracted by the generally smaller amounts of anti-inflammatory products that are secreted. The genetic backgrounds of donors and the recipients may also be of importance, as is the case for alloimmunization, although this is currently very speculative; further research is required to determine the conditions under which donated platelets can be rendered completely safe (with regard to dangerous immune responses). Residual infection due to bacterial contamination is another sensitive issue in platelet component transfusion, although much progress has already been made in this area. Future clinical and experimental studies should be undertaken to complement the current knowledge regarding the safety issues surrounding platelet component transfusion, and to determine the best possible care for patients. Disclosure of interest The authors declare that they have no conflicts of interest concerning this article. 3

Hamzeh-Cognasse et al., submitted for publication.

O. Garraud et al. / Transfusion Clinique et Biologique 19 (2012) 104–108

Acknowledgements We thankfully acknowledge the former and present PhD students who contributed to the original work described here (Julien Berthet, Pauline Damien, and Kim Ahn Nguyen), technicians (Charles-Antoine Arthaud and Marie-Ange Eyraud), and EFS blood bank personnel (Patricia Chavarin, Léna Absi, Halim Benamara, Sophie Acquart, Franc¸oise Boussoulade, and Céline de Putter). We are also grateful to Bruno Pozzetto, head of the University group EA3064, which hosts the Platelet Research group at the EFS Auvergne-Loire, and to Pierre Tiberghien, head of the research program at the Établissement franc¸ais du sang (EFS), Saint-Denis, France. Most of the work presented here benefited from grants from the EFS Research Program, JeanMonnet University, the “Association Recherche Transfusion”, and the Association “Les Amis de Rémi”.

References [1] Semple JW, Italiano Jr JE, Freedman J. Platelets and the immune continuum. Nat Rev Immunol 2011;11:264–74. [2] Aird WC. The role of the endothelium in severe sepsis and multiple organ dysfunction syndrome. Blood 2003;101:3765–77. [3] Blajchman MA, Slichter SJ, Heddle NM, Murphy MF. New strategies for the optimal use of platelet transfusions. Hematology Am Soc Hematol Educ Program 2008:198–204. [4] Andreu G, Vasse J, Tardivel R, Semana G. Platelet transfusion: products, indications, dose, threshold and efficacy. Transfus Clin Biol 2009;16:118–33. [5] Heddle NM, Klama L, Singer J, Richards C, Fedak P, Walker I, et al. The role of the plasma from platelet concentrates in transfusion reactions. N Engl J Med 1994;331:625–8. [6] Stroncek DF, Rebulla P. Platelet transfusions. Lancet 2007;370:427–38. [7] Garraud O, Cognasse F. Platelet Toll-like receptor expression: the link between “danger” ligands and inflammation. Inflamm Allergy Drug Targets 2010;9:322–33. [8] Garraud O, Berthet J, Hamzeh-Cognasse H, Cognasse F. Pathogen sensing, subsequent signalling, and signalosome in human platelets. Thromb Res 2011;127:283–6. [9] Agence franc¸aise de sécurité sanitaire des produits de santé (Afssaps). Rapport annuel hémovigilance 2010. La Plaine-Saint-Denis: Afssaps; 2011 [Disponible à l’adresse: http://www.afssaps.fr/Afssaps-media/ Publications/Bilans-Rapports-d-activite-Bilans-et-rapports-d-activite (accessed 29/2/2012)]. [10] Phipps RP, Kaufman J, Blumberg N. Platelet derived CD154 (CD40 ligand) and febrile responses to transfusion. Lancet 2001;357:2023–4. [11] Blumberg N, Gettings KF, Turner C, Heal JM, Phipps RP. An association of soluble CD40 ligand (CD154) with adverse reactions to platelet transfusions. Transfusion 2006;46:1813–21. [12] Cognasse F, Payrat JM, Corash L, Osselaer JC, Garraud O. Platelet components associated with acute transfusion reactions: the role of plateletderived soluble CD40 ligand. Blood 2008;112:4779–80. [13] Blumberg N, Spinelli SL, Francis CW, Taubman MB, Phipps RP. The platelet as an immune cell-CD40 ligand and transfusion immunomodulation. Immunol Res 2009;45:251–60. [14] Cognasse F, Osselaer JC, Garraud O. Platelets cytokines and their effects on platelet transfusion. Transfus Clin Biol 2007;14:69–78. [15] Garraud O, Cognasse F. Platelet immunology and the immune response. Transfus Clin Biol 2009;16:106–17. [16] Blair P, Flaumenhaft R. Platelet alpha-granules: basic biology and clinical correlates. Blood Rev 2009;23:177–89. [17] Smith TL, Weyrich AS. Platelets as central mediators of systemic inflammatory responses. Thromb Res 2011;127:391–4.

107

[18] Jurk K, Kehrel BE. Platelets: physiology and biochemistry. Semin Thromb Hemost 2005;31:381–92. [19] Andrews RK, Berndt MC. Platelet physiology and thrombosis. Thromb Res 2004;114:447–53. [20] Italiano Jr JE, Mairuhu AT, Flaumenhaft R. Clinical relevance of microparticles from platelets and megakaryocytes. Curr Opin Hematol 2010;17:578–84. [21] Stack G, Snyder EL. Cytokine generation in stored platelet concentrates. Transfusion 1994;34:20–5. [22] Macaulay IC, Carr P, Gusnanto A, Ouwehand WH, Fitzgerald D, Watkins NA. Platelet genomics and proteomics in human health and disease. J Clin Invest 2005;115:3370–7. [23] Thon JN, Schubert P, Devine DV. Platelet storage lesion: a new understanding from a proteomic perspective. Transfus Med Rev 2008;22:268–79. [24] Schubert P, Devine DV. Proteomics meets blood banking: identification of protein targets for the improvement of platelet quality. J Proteomics 2010;73:436–44. [25] Devine DV, Serrano K. The platelet storage lesion. Clin Lab Med 2010;30:475–87. [26] Cognasse F, Boussoulade F, Chavarin P, Acquart S, Fabrigli P, Lamy B, et al. Release of potential immunomodulatory factors during platelet storage. Transfusion 2006;46:1184–9. [27] Fong KP, Barry C, Tran AN, Traxler EA, Wannemacher KM, Tang HY, et al. Deciphering the human platelet sheddome. Blood 2011;117: e15–26. [28] Cooling LL, Kelly K, Barton J, Hwang D, Koerner TA, Olson JD. Determinants of ABH expression on human blood platelets. Blood 2005;105:3356–64. [29] Rozman P. Platelet antigens. The role of human platelet alloantigens (HPA) in blood transfusion and transplantation. Transpl Immunol 2002;10:165–81. [30] Blumberg N, Phipps RP, Kaufman J, Heal JM. The causes and treatment of reactions to platelet transfusions. Transfusion 2003;43:291–2 [author reply 2]. [31] Refaai MA, Phipps RP, Spinelli SL, Blumberg N. Platelet transfusions: impact on hemostasis, thrombosis, inflammation and clinical outcomes. Thromb Res 2011;127:287–91. [32] Khan SY, Kelher MR, Heal JM, Blumberg N, Boshkov LK, Phipps R, et al. Soluble CD40 ligand accumulates in stored blood components, primes neutrophils through CD40, and is a potential cofactor in the development of transfusion-related acute lung injury. Blood 2006;108: 2455–62. [33] Chavarin P, Cognasse F, Argaud C, Vidal M, De Putter C, Boussoulade F, et al. In vitro assessment of apheresis and pooled buffy coat platelet components suspended in plasma and SSP+ photochemically treated with amotosalen and UVA for pathogen inactivation (INTERCEPT Blood System). Vox Sang 2011;100:247–9. [34] Fitzgerald JR, Foster TJ, Cox D. The interaction of bacterial pathogens with platelets. Nat Rev Microbiol 2006;4:445–57. [35] Clemetson KJ. Platelets and pathogens. Cell Mol Life Sci 2010;67:495–8. [36] Yeaman MR. Platelets in defense against bacterial pathogens. Cell Mol Life Sci 2010;67:525–44. [37] Cognasse F, Hamzeh-Cognasse H, Garraud O. Platelets “Toll-like receptor” engagement stimulates the release of immunomodulating molecules. Transfus Clin Biol 2008;15:139–47. [38] Cognasse F, Hamzeh H, Chavarin P, Acquart S, Genin C, Garraud O. Evidence of Toll-like receptor molecules on human platelets. Immunol Cell Biol 2005;83:196–8. [39] Shiraki R, Inoue N, Kawasaki S, Takei A, Kadotani M, Ohnishi Y, et al. Expression of Toll-like receptors on human platelets. Thromb Res 2004;113:379–85. [40] Cox D, Kerrigan SW, Watson SP. Platelets and the innate immune system: mechanisms of bacterial-induced platelet activation. J Thromb Haemost 2011;9:1097–107. [41] Assinger A, Laky M, Schabbauer G, Hirschl AM, Buchberger E, Binder BR, et al. Efficient phagocytosis of periodontopathogens by neutrophils requires plasma factors, platelets and TLR2. J Thromb Haemost 2011;9:799–809.

108

O. Garraud et al. / Transfusion Clinique et Biologique 19 (2012) 104–108

[42] Keane C, Tilley D, Cunningham A, Smolenski A, Kadioglu A, Cox D, et al. Invasive Streptococcus pneumoniae trigger platelet activation via Toll-like receptor 2. J Thromb Haemost 2010;8:2757–65. [43] Kalvegren H, Skoglund C, Helldahl C, Lerm M, Grenegard M, Bengtsson T. Toll-like receptor 2 stimulation of platelets is mediated by purinergic P2X1-dependent Ca2+ mobilisation, cyclooxygenase and purinergic P2Y1 and P2Y12 receptor activation. Thromb Haemost 2010;103:398–407. [44] Zhang G, Han J, Welch EJ, Ye RD, Voyno-Yasenetskaya TA, Malik AB, et al. Lipopolysaccharide stimulates platelet secretion and potentiates platelet aggregation via TLR4/MyD88 and the cGMP-dependent protein kinase pathway. J Immunol 2009;182:7997–8004. [45] Hashimoto K, Jayachandran M, Owen WG, Miller VM. Aggregation and microparticle production through toll-like receptor 4 activation in platelets from recently menopausal women. J Cardiovasc Pharmacol 2009;54:57–62. [46] Shashkin PN, Brown GT, Ghosh A, Marathe GK, McIntyre TM. Lipopolysaccharide is a direct agonist for platelet RNA splicing. J Immunol 2008;181:3495–502. [47] Cognasse F, Hamzeh-Cognasse H, Lafarge S, Delezay O, Pozzetto B, McNicol A, et al. Toll-like receptor 4 ligand can differentially modulate the release of cytokines by human platelets. Br J Haematol 2008;141:84–91. [48] Blair P, Rex S, Vitseva O, Beaulieu L, Tanriverdi K, Chakrabarti S, et al. Stimulation of Toll-like receptor 2 in human platelets induces a thromboinflammatory response through activation of phosphoinositide 3-kinase. Circ Res 2008;104:346–54. [49] Semple JW, Aslam R, Kim M, Speck ER, Freedman J. Platelet-bound lipopolysaccharide enhances Fc receptor-mediated phagocytosis of IgGopsonized platelets. Blood 2007;109:4803–5. [50] Clark SR, Ma AC, Tavener SA, McDonald B, Goodarzi Z, Kelly MM, et al. Platelet TLR4 activates neutrophil extracellular traps to ensnare bacteria in septic blood. Nat Med 2007;13:463–9. [51] Stahl AL, Svensson M, Morgelin M, Svanborg C, Tarr PI, Mooney JC, et al. Lipopolysaccharide from enterohemorrhagic Escherichia coli binds to platelets via TLR4 and CD62 and is detected on circulating platelets in patients with hemolytic uremic syndrome. Blood 2006;108:167–76. [52] Damas JK, Jensenius M, Ueland T, Otterdal K, Yndestad A, Froland SS, et al. Increased levels of soluble CD40L in African tick bite fever: possible involvement of TLRs in the pathogenic interaction between Rickettsia africae, endothelial cells, and platelets. J Immunol 2006;177:2699–706. [53] Aslam R, Speck ER, Kim M, Crow AR, Bang KW, Nestel FP, et al. Platelet Toll-like receptor expression modulates lipopolysaccharideinduced thrombocytopenia and tumor necrosis factor-alpha production in vivo. Blood 2006;107:637–41. [54] Andonegui G, Kerfoot SM, McNagny K, Ebbert KV, Patel KD, Kubes P. Platelets express functional Toll-like receptor-4. Blood 2005;106:2417–23. [55] Brown GT, McIntyre TM. Lipopolysaccharide signaling without a nucleus: kinase cascades stimulate platelet shedding of proinflammatory IL-1betarich microparticles. J Immunol 2011;186:5489–96. [56] Berthet J, Damien P, Hamzeh-Cognasse H, Pozzetto B, Garraud O, Cognasse F. Toll-like receptor 4 signal transduction in platelets: novel pathways. Br J Haematol 2010;151:89–92. [57] Fung CY, Jones S, Ntrakwah A, Naseem KM, Farndale RW, MahautSmith MP. Platelet Ca2+ responses coupled to glycoprotein VI and Toll-like

[58]

[59]

[60] [61]

[62]

[63]

[64]

[65]

[66]

[67]

[68]

[69]

[70]

[71]

[72]

receptors persist in the presence of endothelial-derived inhibitors: roles for secondary activation of P2X1 receptors and release from intracellular Ca2+ stores. Blood 2012;119:3613–21. Liu F, Morris S, Epps J, Carroll R. Demonstration of an activation regulated NF-kappaB/I-kappaBalpha complex in human platelets. Thromb Res 2002;106:199–203. Spinelli SL, Casey AE, Pollock SJ, Gertz JM, McMillan DH, Narasipura SD, et al. Platelets and megakaryocytes contain functional nuclear factor{kappa}B. Arterioscler Thromb Vasc Biol 2010;30:591–8. Spinelli SL, Maggirwar SB, Blumberg N, Phipps RP. Nuclear emancipation: a platelet tour de force. Sci Signal 2010;3:pe37. Sahler J, Bernard JJ, Spinelli SL, Blumberg N, Phipps RP. The Feverfew plant-derived compound, parthenolide enhances platelet production and attenuates platelet activation through NF-kappaB inhibition. Thromb Res 2011;127:426–34. Rahman M, Zhang S, Chew M, Ersson A, Jeppsson B, Thorlacius H. Platelet-derived CD40L (CD154) mediates neutrophil upregulation of Mac1 and recruitment in septic lung injury. Ann Surg 2009;250:783–90. Cognasse F, Osselaer JC, Payrat JM, Chavarin P, Corash L, Garraud O. Release of immune modulation factors from platelet concentrates during storage after photochemical pathogen inactivation treatment. Transfusion 2008;48:809–13. Cognasse F, Hamzeh-Cognasse H, Lafarge S, Chavarin P, Cogne M, Richard Y, et al. Human platelets can activate peripheral blood B cells and increase production of immunoglobulins. Exp Hematol 2007;35: 1376–87. Lee SP, Ataga KI, Orringer EP, Phillips DR, Parise LV. Biologically active CD40 ligand is elevated in sickle cell anemia: potential role for platelet-mediated inflammation. Arterioscler Thromb Vasc Biol 2006;26: 1626–31. Nagasawa M, Zhu Y, Isoda T, Tomizawa D, Itoh S, Kajiwara M, et al. Analysis of serum soluble CD40 ligand (sCD40L) in the patients undergoing allogeneic stem cell transplantation: platelet is a major source of serum sCD40L. Eur J Haematol 2005;74:54–60. Langer F, Ingersoll SB, Amirkhosravi A, Meyer T, Siddiqui FA, Ahmad S, et al. The role of CD40 in CD40L- and antibody-mediated platelet activation. Thromb Haemost 2005;93:1137–46. Chakrabarti S, Varghese S, Vitseva O, Tanriverdi K, Freedman JE. CD40 ligand influences platelet release of reactive oxygen intermediates. Arterioscler Thromb Vasc Biol 2005;25:2428–34. Harding SA, Sommerfield AJ, Sarma J, Twomey PJ, Newby DE, Frier BM, et al. Increased CD40 ligand and platelet-monocyte aggregates in patients with type 1 diabetes mellitus. Atherosclerosis 2004;176:321–5. Prasad KS, Andre P, He M, Bao M, Manganello J, Phillips DR. Soluble CD40 ligand induces beta3 integrin tyrosine phosphorylation and triggers platelet activation by outside-in signaling. Proc Natl Acad Sci U S A 2003;100:12367–71. Buchner K, Henn V, Grafe M, de Boer OJ, Becker AE, Kroczek RA. CD40 ligand is selectively expressed on CD4+ T cells and platelets: implications for CD40-CD40L signalling in atherosclerosis. J Pathol 2003;201:288–95. Henn V, Slupsky JR, Grafe M, Anagnostopoulos I, Forster R, MullerBerghaus G, et al. CD40 ligand on activated platelets triggers an inflammatory reaction of endothelial cells. Nature 1998;391:591–4.