BACKGROUNDTransfusion‐related acute lung injury (TRALI) is a severe pulmonary reaction due to blood transfusions. The pathophysiology of this complication is still not widely elucidated by the scientific community, especially regarding the direct role of blood platelets within the cellular mechanism responsible for the development of TRALI.STUDY DESIGN AND METHODSIn this study, a mouse model was used to induce the development of antibody‐mediated acute lung injury through injections of lipopolysaccharide and an anti–major histocompatibility complex Class I antibody. BALB/c mice were pretreated with an anti‐GPIbα antibody, which induces platelet depletion, or ML354, a protease receptor 4 pathway inhibitor, 30 minutes before TRALI induction.RESULTSDepletion of platelets before TRALI induction appeared to reduce the severity of TRALI without completely inhibiting its development. Also, inhibition of platelet activation by ML354 did not prevent the onset of TRALI. Finally, the stimuli used for TRALI induction also triggered specific platelet activation upon ex vivo stimulation.CONCLUSIONSThis study suggests that blood platelets are not critically required for TRALI induction, although they are to some extent involved in its pathophysiology.

Endocan est une glycoprotéine exprimée par l'endothélium vasculaire dont le rôle est de maintenir l'intégrité de la paroi vasculaire et assurer l'imperméabilité de la barrière endothéliale face aux composés sanguins. Après libération, endocan peut se fixer aux récepteurs leucocytaires ayant préalablement adhéré aux cellules endothéliales par le complexe LFA-1/ICAM-1, limitant ainsi la transmigration endothéliale des leucocytes dans le tissu interstitiel. La libération d'encodan est donc augmentée dans le but de contrer l'atteinte de l'endothélium vasculaire. Au cours de cette étude, le but était de mettre en évidence l'influence inflammatoire des composés présents dans les milieux de conservation des concentrés plaquettaires, associé au développement de réactions post-transfusionnelles, sur l'endothélium vasculaire et d'évaluer la libération d'endocan depuis ce dernier. Nous avons pu observer une exacerbation de l'état inflammatoire des cellules endothéliales caractérisé par une libération plus importante de médiateurs solubles comme IL-6, mais également endocan, lorsque ces cellules sont stimulées avec des surnageants de CP liés à des réactions transfusionnelles par rapport à des surnageants de CP sans induction pathologique chez le receveur. Cette production endothéliale est corrélée avec une prolifération cellulaire réduite et une apoptose plus accrue. Ainsi, comme pour d'autres pathologies inflammatoires, nous pourrions envisager la mesure de la concentration plasmatique d'endocan comme un marqueur précoce de la lésion inflammatoire de l'endothélium et donc de réactions post-transfusionnelles inflammatoires.

La lésion pulmonaire aiguë transfusionnelle (TRALI), est une réaction grave. La physiopathologie de cette complication n'est pas encore très bien admise par la communauté scientifique, notamment en ce qui concerne le rôle des plaquettes sanguines au sein de la mécanistique cellulaire responsable du développement du TRALI. Au cours de cette étude, des travaux préliminaires sont proposés pour tenter de répondre en partie à cette interrogation. Un modèle murin a été utilisé pour induire le développement d'un ALI par des injections successives de lipopolysaccharide et d'anticorps anti-CMH I. Des traitements préalables à base d'anticorps anti-GPIbα, initiateur d'une déplétion plaquettaire, et de ML354, molécule inhibitrice de la voie d'activation du récepteur PAR-4, ont été administrés à des souris BALB/c 30 min avant l'induction de la pathologie. La déplétion plaquettaire, préalable à l'induction de l'ALI, semble réduire la sévérité liée à la lésion pulmonaire aiguë, sans en inhiber entièrement son développement. En revanche, le traitement à base de ML354 n'a prouvé aucune efficacité. Enfin, nous avons pu observer une activation spécifique des plaquettes lors de stimulation, ex vivo, avec les mêmes stimuli utilisés pour déclencher l'ALI dans notre modèle murin. À ce stade, cette étude propose que les plaquettes sanguines soient, au moins secondairement, impliquée dans la physiopathologie du TRALI.

BACKGROUND: Beyond their role in hemostasis and thrombosis, platelets are also important mediators of inflammation by the release of hundreds of factors stored in their a-granules. Mutations in Nbeal2 cause gray platelet syndrome (GPS), characterized by the lack of platelet a-granules. This study aims to evaluate the immunological (proinflammatory) effects of platelet a-granules. STUDY DESIGN AND METHODS: We performed an experiment using Nbeal2(-/-) mice, the mouse model of GPS. Systemic inflammation was induced by intravenous injection of lipopolysaccharide (LPS). Inflammatory response was assessed by quantification of inflammatory soluble factors and platelet biological response modifiers. RESULTS: The lack of Nbeal2 (in Nbeal2(-/-) mice, compared with controls) significantly reduced the recruitment of circulating neutrophils and monocytes. Moreover, after LPS injection, there was a significant increase in neutrophil and monocyte counts in control animals, compared with Nbeal2(-/-) mice. The control of inflammation, evaluated by the production of anti-inflammatory cytokines, appeared to be greater in Nbeal2(-/-) mice compared with controls. Conversely, the production of certain inflammatory-soluble mediators known to characterize normal platelet secretion, such as soluble CD40 ligand (sCD40L), was decreased under experimental inflammation in Nbeal2(-/-) mice. CONCLUSIONS: These results show that a-granules play a direct role in platelet-mediated inflammation balance, confirming the need to further investigate platelet-associated inflammatory pathophysiology and inflammatory adverse events related to blood transfusion.

Le TRALI est considéré comme l'une des réactions post-transfusionnelles avec la mortalité la plus élevée. Cette pathologie est caractérisée par une atteinte pulmonaire sévère justifiant ce fort taux de mortalité. La pathogénie du TRALI se rapproche de celle de plusieurs pathologies inflammatoires, telles que la pancréatite ou encore les pathologies inflammatoires de l'intestin. La physiopathologie du TRALI repose sur l'activation de plusieurs cellules de l'inflammation initiant la migration, dans l'espace alvéolaire, de ces mêmes cellules. Lors de la pancréatite une mécanistique similaire, orchestrée par la migration des neutrophiles dans le tissu lésé, peut-être observée. Nous émettons l'hypothèse que lors de l'induction du TRALI, des organes plus profonds, tels que le pancréas, peuvent être une cible secondaire. Comme les deux pathogénies, celle de la pancréatite et du TRALI, sont étroitement liées, nous émettons également l'hypothèse d'une implication du couple protéique CD40/CD40L dans la régulation de la pancréatite induite suite au développement d'un TRALI. En utilisant, ici, un modèle animal de TRALI induite par injection successive de LPS et d'anticorps anti-CMH I et un traitement préventif à base d'anticorps anti-CD40L, nous avons pu démontrer que l'atteinte pancréatique, observée dans notre modèle de TRALI, est sensiblement prévenu lors de l'inhibition du complexe immun CD40/CD40L.

Lors de l'inflammation, les plaquettes sanguines ont la capacité de produire une multitude de médiateurs solubles dont le rôle peut être pro-thrombotique, régulateur de l'activité des cellules voisines mais également pro-inflammatoire. Nous avons investigué la place des sécrétions plaquettaires dans le maintien, l'amplification ou la régulation de l'inflammation en utilisant un modèle de souris Nbeal2 déficientes. En induisant une déficience du gène Nbeal2 chez des souris C57BL6, nous avons pu prévenir la fusion des granules-a avec la membrane plaquettaire et donc la libération de ses composées granulaires. La biogénèse des granules- a était également impactée. La réponse inflammatoire, suite à une injection systémique de LPS, présentait un profil différent, lorsque comparée à des souris à la lignée génétique dite sauvage. En effet, l'aspect anti-inflammatoire semble prépondérant lorsque les souris présentent des plaquettes circulantes déficientes en production de granule- alpha.

Platelet transfusions can cause adverse reactions in their recipients, including transfusion-related acute lung injury (TRALI). The pathophysiology of TRALI depends on a number of signaling pathways and the inflammatory role played by blood platelets remains controversial. Platelets are important in inflammation, particularly via the immunomodulator complex CD40/CD40L. We studied the specific function of the CD40/CD40L interaction in regulating an experimental TRALI Two-hit model. A mouse model of immune TRALI was triggered by injection of LPS and an anti-MHC I antibody, and the effect of injection of a neutralizing anti-CD40L antibody before induction of TRALI investigated. The characteristics of TRALI were decreased body temperature, pulmonary lesions, and immune cell infiltration into the alveolar space. Pulmonary infiltration was evaluated by blood counts of specific immune cells and their detection in lung sections. Inhibition of the CD40/CD40L immunomodulator interaction significantly reduced communication between immune and/or endothelial cells and the development of pulmonary edema. Hence, our results indicate that targeting of the CD40/CD40L interaction could be an important method to prevent TRALI. While considering that our work concerned a mouse model, we postulate that improvement of the conditions under which platelet concentrates are prepared/stored would assist in alleviating the risk of TRALI.

Le TRALI propose une pathogénie très complexe mettant en jeu diverses cellules de l'inflammation, telles que les neutrophiles, les monocytes, les plaquettes et les cellules endothéliales. Même si aucun consensus actuel n'a validé les cellules réellement impliquées (neutrophiles vs monocytes vs macrophages pulmonaires vs plaquettes sanguines) un point commun existe entre toutes ces cellules, l'implication du complexe protéique CD40/CD40L. Les plaquettes sanguines, par la production d'environ 95 % du CD40L soluble, agoniste à la forme membranaire, sont au cœur d'une physiopathologie CD40/CD40L dépendante. Ce couple immun participe activement à l'établissement de l'immunité innée, adaptative et l'inflammation. En ciblant ce complexe protéique, nous avons donc émis l'hypothèse d'une inhibition du développement de l'ALI, caractérisé par un état inflammatoire non régulé, induit dans un modèle murin par des injections successives de LPS et d'anticorps anti-CMH I. Plutôt que l'activation cellulaire, c'est la migration des neutrophiles et des plaquettes sanguines, depuis le compartiment vasculaire jusqu'à l'espace alvéolaire qui a été freinée. En effet, dans le compartiment sanguin, l'inflammation n'est pas limitée sous traitement à base d'anticorps anti-CD40L neutralisant, mais l'action des neutrophiles et des plaquettes au niveau pulmonaire est sensiblement réduite. L'inhibition du couple CD40/CD40L semble, au cours de cette étude, avoir également un impact sur les monocytes, paramètre qui mériterait une investigation plus approfondie. Cette étude met en avant un rôle trop longtemps sous-estimé du complexe protéique CD40/CD40L dans la physiopathologie du TRALI.

BACKGROUNDAcute lung injury (ALI) is a severe complication of transfusion. In a previous study, we saw that inhibition of the CD40/CD40L complex allowed restoration of ALI lesions in an experimental mouse model.OBJECTIVESThis study focused on pancreas‐associated injury development during experimental ALI pathogenesis and its limitation through CD40/CD40L complex inhibition.MATERIALS AND METHODSAn ALI mouse model was established through intraperitoneal lipopolysaccharide and intravenous anti–major histocompatibility complex class I monoclonal antibody injection. Preemption of lesions was achieved with intravenous injection of neutralizing anti‐CD40L monoclonal antibody 30 minutes before the trigger, that is, anti–major histocompatibility complex class I monoclonal antibody administration. Histology and immunoassay analyses were used to evaluate pancreatic lesions.RESULTSALI development induced significant degradation of the lungs and pancreas and was associated with pancreatic lesions. Different scores were established showing more severe injury to the pancreas in ALI conditions; however, injury was significantly reduced through CD40/CD40L complex inhibition.CONCLUSIONThis study supports the idea that several organs are exposed during ALI development, and particularly when such experimental ALI aims at mimicking transfusion‐associated ALI; nevertheless, preventive treatment inhibiting CD40/CD40L (sCD40L) complex formation provides protection from lung disease as well as disease of other organs.

BACKGROUND:Platelet storage lesions are structural and biochemical changes in platelet concentrates (PCs), and depend on variables in collection and processing, as well as secondary procedures and storage conditions; such lesions can be mitigated by the use of platelet additive solutions (PASs). STUDY DESIGN AND METHODS:This study investigated release of the inflammatory markers sCD40L and sCD62P by single-donor apheresis platelet concentrates (SDA-PCs) and buffy coat-derived pooled platelet concentrates (PPCs) before and after storage. SDA-PC and PPC samples (n = 9089) processed by various methods and stored for different durations were obtained following production in one regional setting, the French National Blood Service. Soluble factors were quantified in PC supernatants immediately after processing and at the time of delivery, using biological testing technology (Luminex). RESULTS:SDA-PCs appeared more activated than PPCs at the end of the production step (i.e., prior to storage); however, proinflammatory soluble factors exhibited greater increases in PPCs than in SDA-PCs during storage. In SDA-PCs, PAS-D (65%) led to reduced secretion of sCD62P, but favored secretion of sCD40L, compared with the alternative PAS-E. CONCLUSION:These data stress the importance of the production (processing) steps of PC manufacture and of storage. The extent to which they affect patient outcomes awaits further investigation in clinical studies.

Platelets transfusion is a safe process, but during or after the process, the recipient may experience an adverse reaction and occasionally a serious adverse reaction (SAR). In this review, we focus on the inflammatory potential of platelet components (PCs) and their involvement in SARs. Recent evidence has highlighted a central role for platelets in the host inflammatory and immune responses. Blood platelets are involved in inflammation and various other aspects of innate immunity through the release of a plethora of immunomodulatory cytokines, chemokines, and associated molecules, collectively termed biological response modifiers that behave like ligands for endothelial and leukocyte receptors and for platelets themselves. The involvement of PCs in SARs-particularly on a critically ill patient's context-could be related, at least in part, to the inflammatory functions of platelets, acquired during storage lesions. Moreover, we focus on causal link between platelet activation and immune-mediated disorders (transfusion-associated immunomodulation, platelets, polyanions, and bacterial defense and alloimmunization). This is linked to the platelets' propensity to be activated even in the absence of deliberate stimuli and to the occurrence of time-dependent storage lesions.

As a therapy or a support to other therapies, despite being largely beneficial to patients in general, transfusion it is not devoid of some risks. In a moderate number of cases, patients may manifest adverse reactions, otherwise referred to as transfusion-associated hazards (TAHs). The latest French 2016 haemovigilance report indicates that 93% of TAHs are minor (grade 1), 5.5% are moderate (grade 2) and 1.6% are severe (grade 3), with only five deaths (grade 4) being attributed to transfusion with relative certainty (imputability of level [or grade] 1 to 3). Health-care providers need to be well aware of the benefits and potential risks (to best evaluate and discuss the benefit risk ratio), how to prevent TAHs, the overall costs and the availability of alternative therapeutic options. In high-income countries, most blood establishments (BEs) and hospital blood banks (HBBs) have developed tools for reporting and analysing at least severe transfusion reactions. With nearly two decades of haemovigilance, transfusion reaction databases should be quite informative, though there are four main caveats that prevent it from being fully efficient: (ai) reporting is mainly declarative and is thus barely exhaustive even in countries where it is mandatory by law; (aii) it is often difficult to differentiate between the different complications related to transfusion, diseases, comorbidities and other types of therapies in patients suffering from debilitating conditions; (aiii) there is a lack of consistency in the definitions used to describe and report some transfusion reactions, their severity and their likelihood of being related to transfusion; and (aiv) it is difficult to assess the imputability of a particular BC given to a patient who has previously received many BCs over a relatively short period of time. When compiling all available information published so far, it appears that TAHs can be analysed using different approaches: (bi) their pathophysiological nature; (bii) their severity; (biii) the onset scheme; (biv) a quality assessment (preventable or non-preventable); (bv) their impact on ongoing therapy. Moreover, TAHs can be reported either in a non-integrative or in an integrative way; in the latter case, presentation may also differ when issued by a blood establishment or a treating ward. At some point, a recapitulative document would be useful to gain a better understanding of TAHs in order to decrease their occurrence and severity and allow decision makers to determine action plans: this is what this review attempts to make. This review attempts to merge the different aspects, with a focus on the hospital side, i.e., how the most frequent TAHs can be avoided or mitigated. (C) 2018 Elsevier Masson SAS. All rights reserved.

Even though used systematically with leukocyte reduction, platelet transfusions still cause adverse reactions in recipients. They include Transfusion-Related Acute Lung Injury (TRALI), respiratory distress that occurs within six hours of the transfusion. The pathophysiology of this transfusion complication brings complex cellular communication into play. The role, particularly inflammatory, played by blood platelets in TRALI pathophysiology has been demonstrated, but is still under debate. Blood platelets play a role in inflammation, particularly via the CD40/CD40L (sCD40L) immunomodulator complex. In this study, we examine in particular the specific involvement of the CD40/CD40L (sCD40L) complex in the inflammatory pathogenesis of TRALI. This molecular complex could be a major target in a TRALI prevention strategy. Improving the conditions in which the platelet concentrates (PC) are prepared and stored would contribute to controlling partly the risks of non-immune TRALI.

Platelet transfusions may be associated with certain adverse effects in recipients, potentially caused by the presence of biological response modifiers contained in the platelet concentrates. The aim of this study is to identify the parameters that reflect platelet activation during both the preparation process and the storage of platelet concentrates. A total of 3,949apheresis platelet concentrate samples were studied with regard to parameters related to the donor as well as to the preparation process and their storage. Key glycoproteins characteristic of platelet activation, i.e. soluble CD40L and CD62P, were quantified in platelet concentrate supernatants on completion of their processing and during storage, using Luminex technology. We observed an increase in soluble factors over time. However, the different parameters studied in connection either with the donors or with the donations, such as (i) donor gender, (ii) donor blood group, (iii) time of collection and (iv) type of apheresis separator, do not seem to have any effect on platelet activation or the release of soluble CD40L and CD62P.

Le Transfusion-Related Acute Lung Injury (TRALI) est une détresse respiratoire qui se produit dans les 6 heures suivant la transfusion. La physiopathologie de cette complication transfusionnelle met en jeu une communication cellulaire complexe entre les cellules endothéliales, les plaquettes et les neutrophiles. Le complexe immun CD40/CD40L joue un rôle majeur dans cette triple communication. Dans ce travail, nous avons étudié la fonction spécifique du couple CD40/CD40L dans la régulation du TRALI, dans un modèle murin. Nous avons développé un TRALI immunologique dans un modèle murin déclenché par une double injection de LPS et d’anticorps anti-CMH I. Un anticorps anti-CD40L neutralisant a été injecté avant l’induction du TRALI. Cette pathologie a été caractérisée par une diminution de la température corporelle, des lésions et infiltrations pulmonaires et un faible survie. La numération sanguine et les marqueurs CD41 et Ly6G pulmonaires ont permis une évaluation de l’infiltration alvéolaire. La communication cellulaire a été mesurée à partir d’une étude de cytométrie en flux. Enfin, l’état inflammatoire des souris et le phénotype cellulaire des neutrophiles ont été évalués. L’inhibition du couple CD40/CD40L réduit considérablement le développement de l’œdème pulmonaire. L’anticorps neutralisant anti-CD40L cible principalement la communication cellulaire normalement établie pendant un TRALI et bloque ainsi la migration cellulaire. L’optimisation des conditions dans lesquelles les concentrés de plaquettes sont préparées et stockées permettrait ainsi de contrôler les lésions de stockage, notamment l’évolution des concentrations de sCD40L et ainsi réduire les risques de TRALI.

Les plaquettes jouent un rôle inflammatoire, notamment de par leur capacité à libérer des modificateurs de réponse biologique (BRM). La réaction inflammatoire dans le compartiment vasculaire implique une activation des cellules endothéliales en raison des interactions cellulaires et les BRM infusés avec les produits sanguins. Endocan, qui est un protéoglycane sécrétée par des cellules endothéliales sous le contrôle de cytokines pro-inflammatoires, peut être une réponse sécrétoire corrélée à cette réaction inflammatoire transfusionnelle. Nous avons mesuré, in vitro, l'activité des cellules endothéliales vis-à-vis de l'expression d'endocan après stimulation par des surnageants de concentrés plaquettaires (CP), impliqués dans les effets indésirables receveurs (EIR) ou non (Contrôle). La fonction des plaquettes a été évaluée par quantification du CD62P soluble et de l'endocan. Des tests fonctionnels de surnageants de CP ont été effectués sur des cellules endothéliales EA.Hy926 en les incubant en présence de surnageants de CP de chaque groupe. L'activation des EA.hy926 a été évaluée par leur production en IL-6 et endocan. La sécrétion d'endocan plaquettaire n'a pas été observée lors de l'activation des plaquettes. Une augmentation de la libération d'IL-6 et d'endocan par les EA.hy926 a été observée après incubation avec les surnageants des CP ayant induit un EIR, comparé à celles stimulées par des surnageants de CP contrôles, également en fonction du temps de stockage des CP. La corrélation entre la sécrétion d'endocan et d'IL-6 par les cellules endothéliales suggère que l'endocan puisse être utilisé comme marqueur prédictif de l'inflammation dans un contexte transfusionnel.

The introduction of allogeneic cells is not a natural process, even if the transfusion is therapeutic and — when no alternative exists, as is often the case — essential. Transfusion of cellular products creates some level of danger sensed by recipients. Danger may manifest itself clinically or biologically, in which case we are dealing with recipient adverse reactions. Platelet concentrate transfusion in particular may be responsible for notable adverse reactions. Some appear to be inevitable, while others are tied to recipient factors: either health or genetic characteristics. The authors’ research is specifically focused on platelet storage lesion and stress factors, and the means of controlling them to ensure greater recipient tolerance.

Red blood cell (RBC) transfusion is a life-saving treatment for several pathologies. RBCs for transfusion are stored refrigerated in a preservative solution, which extends their shelf-life for up to 42 days. During storage, the RBCs endure abundant physicochemical changes, named RBC storage lesions, which affect the overall quality standard, the functional integrity and in vivo survival of the transfused RBCs. Some of the changes occurring in the early stages of the storage period (for approximately two weeks) are reversible but become irreversible later on as the storage is extended. In this review, we aim to decipher the duration of RBC storage and inflammatory marker generation. This phenomenon is included as one of the causes of transfusion-related immunomodulation (TRIM), an emerging concept developed to potentially elucidate numerous clinical observations that suggest that RBC transfusion is associated with increased inflammatory events or effects with clinical consequence.

BACKGROUNDPlatelets (PLTs) are prone to activation and the release of biologic response modifiers (BRMs) under storage conditions. The transfusion inflammatory reaction in the vascular compartment involves endothelial cell activation due to cell-cell interactions and BRMs infused with the blood products. Endocan/ESM-1 is a proteoglycan secreted by endothelial cells under the control of proinflammatory cytokines. We aimed to measure endocan activity in supernatants of PLT components (PCs), implicated in serious adverse reactions (SARs) or not (no.AR), sampled at different stages during storage. STUDY DESIGN AND METHODSPLT function, by quantification of soluble CD62P, and their ability to produce endocan were assessed. Functional testing of PC supernatants was performed on EA.hy926 endothelial cells in vitro by exposing them to PC supernatants from each group (no.AR or SARs); EA.hy926 activation was evaluated by their production of interleukin (IL)-6 and endocan. RESULTSPLT endocan secretion was not induced in response to PLT surface molecule agonists, and no significant correlation was observed between sCD62P and endocan concentration after PLT activation. However, we observed a significant increase in the secretion of IL-6 and endocan after EA.hy926 activation by all PC supernatants. IL-6 and endocan secretion were significantly higher for cells stimulated with SAR than those stimulated with no.AR PC supernatants, as well as cell apoptosis. CONCLUSIONThe correlation between the secretion of endocan and that of IL-6 by endothelial cells suggests that endocan can be used as a predictive marker of inflammation for the quality assessment of transfusion grade PLTs.

Red blood cell (RBC) transfusion is a life-saving treatment for several pathologies. RBCs for transfusion are stored refrigerated in a preservative solution, which extends their shelf-life for up to 42 days. During storage, the RBCs endure abundant physicochemical changes, named RBC storage lesions, which affect the overall quality standard, the functional integrity and in vivo survival of the transfused RBCs. Some of the changes occurring in the early stages of the storage period (for approximately two weeks) are reversible but become irreversible later on as the storage is extended. In this review, we aim to decipher the duration of RBC storage and inflammatory marker generation. This phenomenon is included as one of the causes of transfusion-related immunomodulation (TRIM), an emerging concept developed to potentially elucidate numerous clinical observations that suggest that RBC transfusion is associated with increased inflammatory events or effects with clinical consequence.