title: [Platelet-associated CD154: a new interface in haemostasis and in the inflammatory reaction].
abstract: Blood platelets play a crucial part in the blood clotting process by forming the platelet plug. Recent evidence indicates that they are likely to play a key role in the inflammatory reaction via CD154/CD40 interactions. CD40 was known to be widely expressed, for instance on cells of the vasculature including endothelial cells, smooth muscle cells and macrophages. It was also known that the triggering of CD40 on these cells led to the acquisition of an activated pro-inflammatory and pro-coagulant phenotype. It was subsequently shown that platelets express CD154 which is cryptic in unstimulated platelets but is expressed at the platelet surface upon platelet activation. When expressed at the platelet surface and exposed to CD40-expressing vascular cells, the platelet-associated CD154 triggers a variety of pro-inflammatory and pro-coagulant responses including induction of adhesion receptors, release of cytokines and chemokines, induction of tissue factor and of metalloproteinases. Platelet-associated CD154 is also involved in platelet/platelet interactions during platelet aggregation. Furthermore, in vivo models have emphasized the critical role of the platelet-associated CD154 in the progression of atherosclerotic disease and in the stabilization of arterial thrombi. Recent data show that CD40-bearing cells involved in fibrosis such as hepatic stellate cells and glomerular mesangial cells also respond to platelet-associated CD154, thus suggesting a new mechanism by which platelets may be instrumental in the inflammatory diseases of the liver or the kidney. Finally, platelet-associated CD154 has been shown to have immune competence both in vitro and in vivo, observations that open new fields of research on the potential implications of platelets in the immune response and auto-immune diseases.
authors.affiliation: GREF Inserm E362, IFR 66, Université de Bordeaux 2 et Département de Néphrologie, Hôpital Pellegrin, France. yahsou.delmas@chu-bordeaux.fr
authors.forename: Yahsou
authors.initials: Y
authors.lastname: Delmas
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Viallard
authors.forename: Julien
authors.initials: J
authors.lastname: Villeneuve
authors.forename: Christophe
authors.initials: C
authors.lastname: Grosset
authors.forename: Jean-Max
authors.initials: JM
authors.lastname: Pasquet
authors.forename: Julie
authors.initials: J
authors.lastname: Déchanet-Merville
authors.forename: Paquita
authors.initials: P
authors.lastname: Nurden
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Pellegrin
authors.forename: Jean
authors.initials: J
authors.lastname: Rosenbaum
authors.forename: Christian
authors.initials: C
authors.lastname: Combe
authors.forename: Alan T
authors.initials: AT
authors.lastname: Nurden
authors.forename: Jean
authors.initials: J
authors.lastname: Ripoche
mesh_terms: D001402:B-Lymphocytes; D001792:Blood Platelets / Q000276:immunology* / Q000502:physiology; D023201:CD40 Ligand / Q000276:immunology* / Q000502:physiology*; D006487:Hemostasis; D006801:Humans; D007249:Inflammation; D008213:Lymphocyte Activation
chemical_list: D023201:CD40 Ligand