The aim of this thesis was to assess whether platelet, endothelial and coagulation biomarkers of thrombotic risk are increased in ECKD-HD patients. Five individual studies were performed (1) venous blood samples between controls and resting HD patients, (2) simultaneous blood samples between vascular access (VA) and venous samples in HD patients (3) pre and post dialysis from the VA, (4) samples pre and post dialysis in venous samples, (5) a retrospective study of VA thrombosis in HD patients. Venous blood samples were taken from 78 resting healthy volunteers and from 78 HD patients immediately before and 30 minutes after dialysis. We also took blood samples from the VA of 55 patients immediately before and after dialysis. In 26 patients venous and VA samples were taken simultaneously. Our results have shown HD patients potentially have evidence of a prothrombotic state compared to controls. This is further increased by each session of dialysis and is present in both VA and venous samples distant from the site of haemodialysis. We have shown some differences in platelet activation and inflammatory markers between simultaneous VA and venous samples. Furthermore, some of these biomarkers may be associated with a retrospective history of VA occlusion. Our study has shown that in patients with ECKD on HD there may be evidence of an underlying prothrombotic tendency. There is a need to determine the optimal anti-platelet and anti-coagulation therapy in these patients.

At sites of vascular injury, the critical blood clotting enzyme thrombin is generated from prothrombin via Prothrombinase, a macromolecular, Ca2+-dependent enzymatic complex consisting of the serine protease factor Xa and the non-enzymatic cofactor factor Va, assembled on the membranes of activated platelets. Platelets regulate thrombin formation by providing specific binding sites for the components of Prothrombinase and by releasing a platelet-derived factor V/Va molecule that is more procoagulant than its plasma counterpart and partially resistant to proteolytic inactivation. This dissertation identifies and characterizes the subpopulation of platelet-derived factor V/Va that is responsible for the observed protease resistance, and the mechanism by which Prothrombinase bound to platelets differs from a model system using vesicles composed of 75% phosphatidylcholine (PC) and 25% phosphatidylserine (PS), PCPS vesicles. Previous studies have demonstrated that activated platelets release a dissociable pool of factor V/Va and a non-dissociable, membrane-bound pool, which is covalently attached to the platelet membrane through a glycosylphosphatidyl inositol (GPI) anchor. Data described herein demonstrate unequivocally that the pool of platelet-derived factor V/Va that is resistant to proteolytic inactivation by activated protein C is provided exclusively by the non-dissociable GPI-anchored pool. Further, although this factor Va pool is susceptible to proteolysis by plasmin, the fragments formed are associated with sustained and increased cofactor activity. These observations indicate that tethering of factor Va to the membrane surface via a GPI anchor imparts resistance to proteolytic inactivation and sustained thrombin generation at sites of vascular injury. For several years it has been known that Prothrombinase assembled on PCPS vesicles does not mimic that bound to platelets. While both enzymes cleave prothrombin at Arg271 and Arg320 to form thrombin, prothrombin activation proceeds via the prethrombin-2 pathway (initial cleavage at Arg271) on the platelet surface, in contrast to the meizothrombin pathway (initial cleavage at Arg320) on PCPS vesicles. Using thrombin active site inhibitors, we demonstrate that the preference for either pathway is dictated by the conformation in which prothrombin is bound by the membrane-bound enzyme. The prethrombin-2 pathway of prothrombin activation catalyzed by platelet-bound Prothrombinase is a direct consequence of configuring prothrombin in a proteinase-like state resulting in the exposure of a pseudo-active site that can be stabilized by active site thrombin inhibitors. Conversely, prothrombin is preferentially configured in the zymogen-like state on PCPS vesicles where the meizothrombin pathway is preferred. Additional support for the differential assembly of Prothrombinase on the platelet surface is provided by observations made using prethrombin-1, an intermediate formed by cleavage of prothrombin at Arg155 by the formed thrombin. Prethrombin-1 is converted into fragment-2 and thrombin by platelet-bound Prothrombinase at a substantially higher rate than vesicle-bound Prothrombinase. The decreased rate of prethrombin-1 activation in the model system is due, in part, to inhibition of the vesicle-bound enzyme by the fragment-2 generated in the reaction. Taken together, these data not only provide important molecular insights into the mechanisms by which Prothrombinase bound to activated platelets at sites of vascular injury regulates the procoagulant response to effectively support robust thrombin generation, but also provides potential mechanistic sites that could be targeted therapeutically.

Alteração da fosfolipase A2 tem sido descrita em diversas doenças neuropsiquiátricas. Esta enzima é responsável pelo metabolismo dos fosfolípides de membrana e parece estar envolvida na fisiopatologia do transtorno bipolar. Neste estudo, foram analisados os três principais subtipos da PLA2 (sPLA2, cPLA2 e iPLA2) em plaquetas de pacientes e indivíduos controles. A atividade de subtipos de PLA2 foi determinada em 20 pacientes TB sem tratamento com estabilizadores de humor e após seis semanas de tratamento com lítio; 72 pacientes medicados e 65 controles (16 pareados com os pacientes sem tratamento e 49 com os pacientes previamente medicados), pelo método radioenzimático. Os pacientes foram diagnosticados e classificados de acordo com os critérios estabelecidos no DSM-IV-TR. Foi verificado que Os pacientes no estágio inicial da doença apresentaram menor atividade de iPLA2, sPLA2 e cPLA2 quando comparadas ao grupo controle. Seis semanas de tratamento com o lítio não foram suficientes para observar alterações nos resultados obtidos. No entanto, o lítio diminuiu a sintomatologia maníaca e a depressiva, avaliadas pelas escalas de Hamilton e Young, respectivamente (p < 0,01 para as duas comparações). Os pacientes medicados não diferiram do grupo controle para os três subtipos de PLA2 avaliados. Estes resultados sugerem que no estágio inicial do TB há uma diminuição da atividade das PLA2, e que a ação de um ou mais medicamentos que são incluídos na terapêutica para este transtorno podem reverter essa diminuição. Sugere-se ainda que a diminuição da atividade da iPLA2 no estágio inicial do transtorno bipolar, além de alterar o remodelamento da membrana, possa ser um fator de risco para o desenvolvimento de demência nestes pacientes. / Changes in phospholipase A2 have been reported in several psychiatric disorders. This enzyme is responsible for the metabolism of membrane phospholipids and has been suggested to play a role in bipolar disorder physiopathology. In this study, the activity of the three main subtypes of phospholipase A2 (PLA2) were analyzed (sPLA2, cPLA2 and iPLA2) in platelets of BD patients and health subjects. Subjects enrolled were: 20 drug-naïve and drug free BD patients, who were treated with lithium for six weeks; 72 BD long-term treatment patients and 65 controls (16 for the drug-naïve and drug free and 49 for the long term group). PLA2 subtype activities were determined by the radio enzymatic method. Patients\' diagnostic and classification were made according to DSM-IV-TR criteria. Patients at the early stage of the disease presented lower iPLA2, sPLA2 and cPLA2 activity than the control group. Six weeks treatment with lithium did not change these activities. However, lithium reduced the maniac and depressive symptoms, evaluated with Hamilton and Young scales, respectively (p < 0.01, for both comparisons). Long-term treated patients presented similar PLA2 activities to control group. The results suggest that at the early stage of BD iPLA2 activity is decreased and that the adequate treatment of BD could reverse this reduction. We suggest that a reduction of iPLA2 activity at the early stage of BD can modify the membrane metabolism, and could be a risk for the development of dementia in BD patients.

Metastasis is the major cause of cancer related mortality, due to a poor understanding of the metastatic process and a subsequent lack of effective anti-metastatic therapies. Evidence from experimental studies and clinical trials has shown that aspirin reduces the incidence of distant metastases. It is well established that aspirin inhibits cyclooxygenase (COX)-1 and COX-2, triggering anti-thrombotic and anti-inflammatory effects, respectively. However, the mechanisms underlying the anti-metastatic effect of aspirin are still largely unknown. By using an experimental model of pulmonary metastasis, we have found that the anti-metastatic effect of aspirin is associated with the inhibition of COX-1. In support of this, metastasis establishment was impaired in COX-1 deficient mice, suggesting a pivotal role of this isoform in the metastatic process. Looking in more detail into the metastatic cascade, we found that COX-1 contributes to the intravascular phase of metastasis and promotes the early persistence of tumour cells in the lung vasculature. In particular, COX-1 inhibition decreased the interaction of platelets with tumour cells and was associated with the reduction of endothelial activation, of tumour cell adhesion to the endothelium, of recruitment of metastasis-promoting monocytes/macrophages and of transendothelial migration. We have identified platelet-derived thromboxane A₂ (TXA₂) as the main product of COX-1 responsible for its permissive effect on metastasis. Indeed, TXA₂ delivered to mice in combination with aspirin was able to abrogate the anti-metastatic effect of aspirin. Taken together, our data suggest that the inhibition of COX-1:TXA₂ axis by aspirin is sufficient to exert an anti-metastatic effect. In particular, the inhibition of platelet-derived TXA₂ seems to affect multiple early steps of the haematogenous transit of tumour cells. In this perspective, TXA₂ might represent a more selective therapeutic target for the prevention of metastasis.

Statins are 3-hydroxy, 3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, which block the cholesterol biosynthetic pathway to lower total serum levels and LDL-cholesterol. The cholesterol pathway also provides a supply of isoprenoids (farnesyl and geranylgeranyl) for the prenylation of signaling molecules, which include the families of Ras and Rho small GTPases. Prenyl groups provide a membrane anchor that is essential for the correct membrane localisation and function of these proteins. Statins deplete cells of lipid geranylgeranyl diphosphate (GGPP) thereby inhibiting progression of the mevalonate pathway and prenylation of proteins. Two such proteins are Rab27b and Rap1, small GTPase proteins that are involved in the secretion of platelet granule and integrin activation. We hypothesise that statins can impair prenylation of Rab27b and Rap1a in platelets and thereby attenuate platelet function. The specific aims of the project were to analyse the impact of statins on the prenylation status of Rab27b and Rap1a in platelets. As Rab27b and Rap1a are known to be involved in secretion of platelet granules a secondary aim was to analyse the downstream effects of statins on this process following activation. Finally, we assessed the impact of treatment of platelets with statins on thrombus formation, stability and resistance to fibrinolysis. Platelets incubated with statins overnight were separated into cytosolic (aqueous) and membrane (detergent) components and visualised by Western blot. An accumulation of Rab27b and Rap1a was observed in the cytosolic compartments of statins treated platelets compared to untreated platelets, thus indicating indirect evidence that statins attenuate prenylation of Rab27b and Rap1a in platelets. The most effective statin in attenuating prenylation of Rab27b and Rap1a was atorvastatin (ATV). The inhibitory effect of statins on prenylation was recovered by GGPP, indicating that the mechanism of inhibition involved the mevalonate pathway. Release of ADP from platelet dense granules was significantly impeded following overnight treatment with ATV. In line with the inhibition of prenylation of Rab27b and Rap1a by ATV, addition of GGPP rescued the release of ADP from platelet dense granules. This suggests that attenuation of dense granules release by ATV occurs via interference in the mevalonate pathway and the inhibition of Rab27b prenylation. Furthermore, ATV significantly attenuates α-granules release in thrombin stimulated platelets, which was visualised as impaired accumulation of endogenous P-selectin, PAI-1 and fibrinogen on the activated membrane. Changes in the activation of α₁₁bβ₃ integrin on the stimulated platelet surface, observed as defective binding of exogenous fibrinogen and PAC-1, were also evident following treatment of platelets with ATV. In addition, ATV treatment of platelets reduced binding of CD41a, indicating that the copy number and activation of α₁₁bβ₃ integrin on stimulated platelets was significantly reduced. Statins were also found to significantly inhibit thrombin-induced platelet aggregation following incubation of platelets overnight with therapeutic concentrations of statins. Surprisingly GGPP did not rescue platelet aggregation indicating that different mechanisms are involved in inhibition of platelet responses by statins. Incubation of whole blood with ATV overnight significantly altered several haemostatic parameters. Using thromboelastography we demonstrated a delay in the coagulation time and clot formation time. Maximum clot firmness was also significantly reduced in the presence of statins compared to the control. The effect on clot firmness generally arises from platelet dysfunction and/or a change in fibrinogen concentration and function; the latter was ruled out using a Fibtem test, which shows no difference between treated and untreated whole blood. Similarly, formation of platelet-rich plasma clots was significantly delayed following pre-treatment with ATV overnight. These clots also exhibited lower maximal absorbances, which could represent differences in the fibrin network structure. In line with the reduction in fibrinogen binding defective clot retraction was also observed in platelet-rich plasma pre-treated with ATV overnight. Similar clot retraction results were observed with tirofiban and CytoD, suggesting that the inhibitory effect of ATV may involve modulation of α₁₁bβ₃ integrin activation. Platelet-rich plasma clots formed post-treatment with statins were visualised by confocal microscopy and revealed significant alterations in clot structure; observed as thinner fibrin fibres and fewer platelet aggregates. Additionally, we demonstrated that statins modulate clot stability and shorten time to lysis. Clots formed from platelet rich plasma that was subjected to incubation with ATV overnight revealed faster lysis by tPA compared to the absence of statin. These findings are also in agreement with the lysis of Chandler model thrombi formed from overnight incubated whole blood with ATV, which demonstrated faster lysis rate mediated by tPA. Furthermore, statins were shown to change the clot thrombodynamics as assessed by HemaCore analyser, which shows that stains implicate both clot growth in response to TF-coated comb and spontaneous clot lysis by tPA. In conclusion, statins directly inhibit Rab27b and Rap1a prenylation in platelets and down-regulated dense granules release. Inhibition of Rab27b and Rap1a prenylation, and dense granules release was recovered by GGPP, indicating that these effects are mediated through the mevalonate pathway. Impairment of platelet aggregation by statins resulted via multiple mechanisms as GGPP did not recovered the inhibition of aggregation by ATV. Statins also modulate fibrinogen binding, α-granules release, clot retraction and clot formation and stability in vitro. Together these results suggest that statins may directly attenuate the platelet response in vivo. The pleotropic effect of statins on platelets may contribute to the protective function of these class of drugs in cardiovascular diseases.

Depuis quelques années, les plaquettes sanguines sont reconnues comme un véritable élément de l’immunité. En effet, de nombreux rôles clés lors du processus inflammatoire sont attribués aux plaquettes, tels que la détection d’un signal, la libération de nombreux immunomodulateurs ou une forte interaction avec les autres cellules immunitaires. Le constat clinique d’une corrélation entre le taux plaquettaire et la mortalité du sepsis permet de relever l’importance de cette cellule dans la physiopathologie du sepsis. Ainsi ce travail doctoral a eu pour objectif de mettre en relief la part inflammatoire des plaquettes lors des interactions entre les facteurs de virulence de Staphylococcus aureus (S.aureus) que sont différentes exotoxines ou de souches de S. aureus issues de bactériémies de patients septiques. Un modèle expérimental de sepsis murin nous a permis de comprendre la composante inflammatoire jouée par les plaquettes ainsi que leurs implications dans la dysfonction pulmonaire issue lors du sepsis. Enfin, nous avons évalué la modulation de molécules antiplaquettaires, et particulièrement de l’acide acétylsalicylique, sur les nombreux rôles pathogéniques des plaquettes durant cette pathologie. / During some years, platelets are recognized as an key element of immunity. In fact, platelets play several roles, as signal detection, immunomodulator release and interaction with other immunity cells. The clinical significance of a correlation between platelet rate and sepsis mortality reveals the importance of this cell in the pathophysiology of sepsis. Thus, the purpose of this doctoral work was to highlight the inflammatory role of platelets in the interactions between the virulence factors of Staphylococcus aureus (S. aureus) that are different exotoxins or strains of S. aureus from bacteremia of septic patients. An experimental model of murine sepsis allowed us to understand the inflammatory component played by platelets as well as their implications in pulmonary dysfunction resulting from sepsis. Finally, we evaluated the modulation of antiplatelet molecules, particularly acetylsalicylic acid, on the numerous pathogenic roles of platelets during this pathology.

Les plaquettes jouent un rôle primordial dans le processus d'hémostase. Elles sont générées à partir des mégacaryocytes (MK) présents dans la moelle osseuse. En plus des compartiments vésiculaires classiques de la voie d'endocytose et de dégradation vers les lysosomes, les plaquettes possèdent deux compartiments sécrétoires additionnels, les granules alpha et denses. Ces granules sont générés au cours de la maturation des MK à partir des corps multivésiculaires (MVB) et contiennent des molécules essentielles aux fonctions plaquettaires. Un défaut dans la production ou le remplissage de ces granules est à l'origine de symdromes hémorragiques. Malgré des études montrant l'implication de certaines protéines du trafic vésiculaire, les mécanismes moléculaires qui contrôlent la biogenèse et la maintenance des granules plaquettaires dans les MK ainsi que les mécanismes de tri des cargos qu'ils contiennent, ne sont pas complètement élucidés. Au cours de ces dernières années les phosphoinositides (PI) sont apparus comme des acteurs majeurs du trafic vésiculaire en régulant de la localisation de certaines protéines. Cependant, peu de choses sont connues à ce jour quant au rôle de ces lipides dans la biogenèse et le trafic des granules plaquettaires dans les MK. Au cours de ma thèse, j'ai étudié le rôle d'un des membres de la famille des PI, le phosphatidylinositol 5-phosphate (PtdIns5P), ainsi que deux enzymes responsables de sa synthèse : la 3-phosphatase MTM1 (mutée dans la myopathie centronucléaire, CNM) et la lipide kinase PIKfyve, dans le contrôle de la dynamique des granules. Mes résultats montrent que MTM1 est présente dans les MK et les plaquettes et est localisée en partie sur les granules denses. Cependant, cette phosphatase n'est pas essentielle pour la production et l'activation plaquettaire. En effet, les souris MTM1 KO ne présentent pas de défaut du nombre plaquettaire, ni d'agrégation et de sécrétion suite à une stimulation par la thrombine ou le collagène. Nous montrons la présence d'autres membres de la famille des myotubularines dans les plaquettes et les MK différenciés, ce qui pourrait expliquer une redondance de fonction. De façon intéressante, nous montrons que la détection de MTM1 à partir de faible quantité de sang (<100 ?l) pourrait déboucher sur la mise au point d'un test diagnostic rapide pour la détection de la CNM. Mes travaux ont été focalisés par la suite sur PIKfyve. En utilisant la lignée leucémique mégacaryoblastique MEG-01 différenciée, je montre pour la première fois que le PtdIns5P est localisé dans les compartiments endosomes tardifs ainsi que dans les granules alpha et denses. Dans ces cellules, PIKfyve contrôle plus de 50% du PtdIns5P. De façon remarquable, l'inhibition pharmacologique de PIKfyve ou son invalidation par siRNA entraine une perte d'identité des granules avec la formation de granules élargis qui présentent à la fois des marqueurs de granules denses et alpha et bloque totalement leur mobilité. Ces données ont été confirmées dans des MK primaires de souris. L'addition de PtdIns5P exogène sur les MEG-01 restaure le phénotype normal des granules démontrant que PIKfyve, par l'intermédiaire du PtdIns5P, contrôle l'intégrité des granules qui est donc un phénomène actif et les mécanismes de fusion/fission des vésicules affectant le tri des cargos. De plus, l'inhibition de PIKfyve dans les plaquettes isolées affecte leur agrégation et leur sécrétion, montrant que PIKfyve et le PtdIns5P peuvent agir d'une part lors de la biogénèse des plaquettes dans les MK et d'autre part sur le fonctionnement des plaquettes. Dans leur ensemble, mes travaux placent PIKfyve et son produit lipidique, le PtdIns5P, comme des acteurs majeurs de la maintenance et l'identité des granules plaquettaires. / Platelets play a major role in homeostasis processes. They are generated from megakaryocytes (MKs) in the bone marrow. In addition to the classic vesicular compartments of the endocytic and degradation pathway toward lysosomes, platelets have two additional specialized secretory compartments, the dense and alpha granules. These granules are made during MK maturation from multivesicular bodies (MVB) and contain molecules that are essential to platelet functions. Defect in the production of these granules or absence of their cargos is the cause of hemorrhagic syndromes. Despite many studies showing the implication of vesicle trafficking proteins, the molecular mechanisms controlling the biogenesis and maintenance of the granules and cargo sorting are not completely understood. In recent years, phosphoinositides (PIs) have emerged as key actors in vesicular trafficking playing a role of important spatial regulators of many proteins. However, little is known about the role of these lipids in the biogenesis and the trafficking of platelet granules in the MK.During my thesis, I have studied the role of one the member of the PI family, the phosphatidylinositol 5-phosphate (PtdIns5P), and of two enzymes responsible of its synthesis : the 3-phosphatase MTM1(mutated in the Centronuclear myopathy, CNM) and the lipid kinase PIKfyve, in the control of granules dynamic. My results show that MTM1 is present in MK and platelet and that platelet MTM1 localizes in part on dense granules. However, the phosphatase is not mandatory for platelet production and activation. Indeed, the knock-out of MTM1 in mice has no effect on platelet count, aggregation and secretion following thrombin or collagen stimulation. We show the presence of other members of the myotubularins family in platelet and differentiated MK, which can explain a redundancy in functions. Interestingly, we show that MTM1 detection from small amount of blood (<100 ?l) could lead to the development of a rapid diagnostic test for the detection of the CNM. My work was next focalized on PIKfyve. Using the differentiated leukemic megakaryoblastic cell line MEG-01 as a cell model, I showed for the first time that PtdIns5P is localized on late endosome and on alpha and dense granules. In these cells, PIKfyve controls more than 50% of cellular PtdIns5P. Remarkably, pharmacological inhibition of PIKfyve or its invalidation by siRNA leads to a loss of granules identity with the formation of enlarged granules containing both alpha and dense granules markers, and totally blocks their mobility. These data were also confirmed on primary mice MK. Addition of exogenous PtdIns5P on MEG-01 cells restores the normal phenotype of granules showing that PIKfyve, via PtdIns5P, controls granules integrity, an active phenomenon, and the fusion/fission mechanisms that affect cargos sorting. Furthermore, PIKfyve inhibition in isolated platelet affects their aggregation and secretion, showing that PIKfyve and the PtdIns5P may act on the biogenesis of platelets in MK and also on the function of mature platelets. In conclusion, my Ph.D. work shows that PIKfyve and its product PtdIns5P are major actors in platelet granules maintenance and integrity.

La transfusion sanguine permet de sauver des vies et réduit la morbidité pour un grand nombre de maladies et d'affections cliniques, mais elle n'est pas exempte de complications. Un incident néfaste lié à une transfusion, également appelé Effet Indésirable Receveur (EIR), est un incident défavorable survenant chez un patient pendant ou après une transfusion sanguine. Parmi eux, le TRALI est considéré comme l’une des réactions inflammatoires les plus critiques. Cette pathologie se développe généralement dans les 6 heures après transfusion. On en reconnaît deux types, les TRALI immunologiques et les TRALI non-immunologiques. En France, les premiers sont presque entièrement prévenus par une politique de sécurité des produits sanguins, tandis que la fréquence des seconds augmente. La physiopathologie du TRALI reste mal connue. Tandis que certains y accordent une place importante aux plaquettes sanguines du patient transfusé, d’autres les considèrent comme pas réellement impliquées. Le but de ce travail de thèse a été, dans un premier temps, d’investiguer le potentiel inflammatoire des plaquettes sanguines conservées dans les concentrés plaquettaires et l’influence de cette inflammation sur l’endothélium vasculaire général. Ensuite, sera évalué le rôle des plaquettes sanguines de l’organisme, notamment par l’intermédiaire de leurs produits de sécrétion, dans la pathogénie de cette complication transfusionnelle. Pour cela, un ALI (mimant un TRALI) a été déclenché, dans un modèle in vivo, par une injection d’anticorps anti-CMH I chez des souris préalablement stimulées avec du LPS. L’ensemble de nos résultats confirme le potentiel inflammatoire des plaquettes sanguines, au sein des concentrés plaquettaires, pouvant probablement assumer l’entière responsabilité du déclenchement d’un TRALI non-immunologique, ainsi qu’un rôle secondaire des plaquettes sanguines de l’organisme, participant activement à l’amplification de la sévérité de la pathologie. Cette thèse s’inscrit dans la continuité logique des études menées, au sein du laboratoire GIMAP-EA3064, investiguant la place des plaquettes sanguines au sein de l’inflammation, ouvrant ainsi de nouvelles perspectives dans la sécurité transfusionnelle. / Blood transfusion saves lives and reduces morbidity for many diseases and clinical conditions, but it is not without complications. A transfusion-related adverse event, also known as the Adverse Reaction (AR), is an incident occurring in a patient during or after a blood transfusion. Among them, TRALI is considered as one of the most critical inflammatory reactions. This pathology usually occurs within 6 hours after transfusion. Two types are recognized: immune TRALI and non-immune TRALI. In France, the first is almost completely prevented by a blood product safety policy, while the frequency of the second increases. The pathophysiology of TRALI remains poorly understood. While some scientists give an important function of patient blood platelets, others consider them dispensable. The aim of this thesis was, first, to investigate the inflammatory potential of blood platelets stored in platelet concentrates and its impact on the general vascular endothelium. Next, the role of patient blood platelets, including their secretory products, in the pathogenesis of this transfusion complication will be evaluated. For it, an ALI (mimicking a TRALI) was triggered, in an in vivo model, by an injection of anti-MHC I antibody in mice previously stimulated with LPS. Our results confirm the inflammatory potential of blood platelets in platelet concentrates, which can probably assume the entire responsibility for triggering a non-immune TRALI, and a secondary role for patient blood platelets in the amplification of the severity of this pathology. This thesis is the continuity of studies conducted in the laboratory GIMAP-EA3064, investigating the function of blood platelets in inflammation, thus opening up new perspectives in transfusion safety.

No description available.

Copies of author's previously published articles inserted. / Includes bibliographical references. / xiii, 231, [145] leaves, [2] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Aims to analyse the interactions and to identify synergism occurring between the combinations of adrenaline with ADP and 5-HT with ADP ; and to identify the intraplatelet mechanism involved in signalling the initiation of the enhanced aggregation response. / Thesis (Ph.D.)--University of Adelaide, Dept. of Clinical and Experimental Pharmacology, 1995?