The risk of COVID-19 death is much greater and age dependent with type I IFN autoantibodies.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection fatality rate (IFR) doubles with every 5 y of age from childhood onward. Circulating autoantibodies neutralizing IFN-α, IFN-ω, and/or IFN-ß are found in ∼20% of deceased patients across age groups, and in ∼1% of individuals aged <70 y and in >4% of those >70 y old in the general population. With a sample of 1,261 unvaccinated deceased patients and 34,159 individuals of the general population sampled before the pandemic, we estimated both IFR and relative risk of death (RRD) across age groups for individuals carrying autoantibodies neutralizing type I IFNs, relative to noncarriers. The RRD associated with any combination of autoantibodies was higher in subjects under 70 y old. For autoantibodies neutralizing IFN-α2 or IFN-ω, the RRDs were 17.0 (95% CI: 11.7 to 24.7) and 5.8 (4.5 to 7.4) for individuals <70 y and ≥70 y old, respectively, whereas, for autoantibodies neutralizing both molecules, the RRDs were 188.3 (44.8 to 774.4) and 7.2 (5.0 to 10.3), respectively. In contrast, IFRs increased with age, ranging from 0.17% (0.12 to 0.31) for individuals <40 y old to 26.7% (20.3 to 35.2) for those ≥80 y old for autoantibodies neutralizing IFN-α2 or IFN-ω, and from 0.84% (0.31 to 8.28) to 40.5% (27.82 to 61.20) for autoantibodies neutralizing both. Autoantibodies against type I IFNs increase IFRs, and are associated with high RRDs, especially when neutralizing both IFN-α2 and IFN-ω. Remarkably, IFRs increase with age, whereas RRDs decrease with age. Autoimmunity to type I IFNs is a strong and common predictor of COVID-19 death.

Impact of Intraoperative Allogeneic Platelet Transfusion on Healthcare-Associated Infections in Cardiac Surgery: Insights From a Large Single-Center Cohort Study.

OBJECTIVES: Despite significant improvement in patient blood management, cardiac surgery remains a high hemorrhagic risk procedure. Platelet transfusion is used commonly to treat thrombocytopenia-associated perioperative bleeding. Allogeneic platelet transfusion may induce transfusion-related immunomodulation. However, its association with postoperative healthcare-associated infections is still a matter of debate. The objective was to evaluate the impact of allogeneic platelet transfusion during cardiac surgery on postoperative healthcare-associated infection incidence. DESIGN: Retrospective cohort study. SETTING: Tertiary referral academic center. PARTICIPANTS: Patients undergoing cardiac surgery from 2012 to 2018. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Intraoperative platelet transfusion was defined as exposure in a causal model. The primary outcome was the incidence of healthcare-associated infections comprised of bloodstream infection, hospital-acquired pneumonia, and surgical-site infection. Among 7,662 included patients, 528 patients (6.8%) were exposed to intraoperative platelet transfusion, and 329 patients (4.3%) developed 454 postoperative infections. Bloodstream infection affected 106 patients (1.4%), hospital-acquired pneumonia affected 174 patients (2.3%), and surgical-site infection affected 148 patients (1.9%). Intraoperative platelet transfusion was associated with an increased risk of bloodstream infection after adjustment by multivariable logistic regression (odds ratio [OR] 2.85; 95% CI 1.40-5.8; p = 0.004; n = 7,662), propensity score matching (OR 3.95; 95% CI 1.57-12.0), p = 0.007; n = 766), and propensity score overlap weighting (OR 3.04; 95% CI 1.51-6.1, p = 0.002; n = 7,762). Surgical-site infection and hospital-acquired pneumonia were not significantly associated with platelet transfusion. CONCLUSIONS: These results suggested that intraoperative allogeneic platelet transfusion is a risk factor for bloodstream infection after cardiac surgery. These results supported the development of patient blood management strategies aimed at minimizing perioperative platelet transfusion in cardiac surgery.

Platelet EVs contain an active proteasome involved in protein processing for antigen presentation via MHC-I molecules.

In addition to their hemostatic role, platelets play a significant role in immunity. Once activated, platelets release extracellular vesicles (EVs) formed by the budding of their cytoplasmic membranes. Because of their heterogeneity, platelet EVs (PEVs) are thought to perform diverse functions. It is unknown, however, whether the proteasome is transferred from platelets to PEVs or whether its function is retained. We hypothesized that functional protein processing and antigen presentation machinery are transferred to PEVs by activated platelets. Using molecular and functional assays, we found that the active 20S proteasome was enriched in PEVs, along with major histocompatibility complex class I (MHC-I) and lymphocyte costimulatory molecules (CD40L and OX40L). Proteasome-containing PEVs were identified in healthy donor blood, but did not increase in platelet concentrates that caused adverse transfusion reactions. They were augmented, however, after immune complex injections in mice. The complete biodistribution of murine PEVs after injection into mice revealed that they principally reached lymphoid organs, such as spleen and lymph nodes, in addition to the bone marrow, and to a lesser extent, liver and lungs. The PEV proteasome processed exogenous ovalbumin (OVA) and loaded its antigenic peptide onto MHC-I molecules, which promoted OVA-specific CD8+ T-lymphocyte proliferation. These results suggest that PEVs contribute to adaptive immunity through cross-presentation of antigens and have privileged access to immune cells through the lymphatic system, a tissue location that is inaccessible to platelets.

Associations of potential plasma biomarkers with suicide attempt history, current suicidal ideation and subsequent suicidal events in patients with depression: A discovery study.

A growing body of evidences suggests that suicidal ideation (SI) and suicidal behaviors have biological bases. However, no biological marker is currently available to evaluate the suicide risk in individuals with SI or suicide attempt (SA). Moreover, the current risk assessment techniques poorly predict future suicidal events. The aim of this study was to examine the association of 39 new and already described peripheral cells and proteins (implicated in the immune system, oxidative stress and plasticity) with lifetime SA, past month SA, current SI, and future suicidal events (visit to the Emergency Department for SI or SA) in 266 treatment-seeking individuals with mood disorders. Equal parts of patients with and without past history of SA were recruited. All individuals at inclusion gave blood, were evaluated for SA recency, current SI, and were followed for two years afterwards. The 39 peripheral blood cellular and protein markers were entered separately for each outcome in Elastic Net models with 10-fold cross-validation, followed by single-analyte covariate-adjusted regression analyses for pre-selected analytes. Past month SA was associated with increased plasma levels of thrombospondin-2 and C-reactive protein, whereas current SI was associated with lower plasma serotonin levels. These associations were robust to adjustments for key covariates and corrections for multiple testing. The Cox proportional hazards regression showed that higher levels of thrombospondin-1 and of platelet-derived growth factor-AB predicted a future suicidal event. These two associations remained after adjustment for sex, age, and SA history, and outperformed the predictive value of past SA. Thrombospondins and platelet-derived growth factors have never been investigated in the context of suicide. Altogether, our results highlight the involvement in the suicidal process of platelet biological response and plasticity modifiers and also of inflammatory factors. They also suggest that SI and SA may have different biological correlates and that biomarkers associated with past SA or current SI do not automatically also predict future events.

Quality assessment of red blood cell concentrates from blood donors at the extremes of the age spectrum: The BEST collaborative study.

BACKGROUND: Blood donors at the extremes of the age spectrum (16-19 years vs. ≥75 years) are characterized by increased risks of iron deficiency and anemia, and are often underrepresented in studies evaluating the effects of donor characteristics on red blood cells (RBC) transfusion effectiveness. The aim of this study was to conduct quality assessments of RBC concentrates from these unique age groups. STUDY DESIGN: We characterized 150 leukocyte-reduced (LR)-RBCs units from 75 teenage donors, who were matched by sex, and ethnicity with 75 older donors. LR-RBC units were manufactured at three large blood collection centers in the USA and Canada. Quality assessments included storage hemolysis, osmotic hemolysis, oxidative hemolysis, osmotic gradient ektacytometry, hematological indices, and RBC bioactivity. RESULTS: RBC concentrates from teenage donors had smaller (9%) mean corpuscular volume and higher (5%) RBC concentration compared with older donors counterparts. Stored RBCs from teenage donors exhibited increased susceptibility to oxidative hemolysis (>2-fold) compared with RBCs from older donors. This was observed at all testing centers independent of sex, storage duration, or the type of additive solution. RBCs from teenage male donors had increased cytoplasmatic viscosity and lower hydration compared with older donor RBCs. Evaluations of RBC supernatant bioactivity suggested that donor age was not associated with altered expression of inflammatory markers (CD31, CD54, and IL-6) on endothelial cells. CONCLUSIONS: The reported findings are likely intrinsic to RBCs and reflect age-specific changes in RBC antioxidant capacity and physical characteristics that may impact RBC survival during cold storage and after transfusion.

Assessment of the soluble proteins HMGB1, CD40L and CD62P during various platelet preparation processes and the storage of platelet concentrates: The BEST collaborative study.

BACKGROUND: Structural and biochemical changes in stored platelets are influenced by collection and processing methods. This international study investigates the effects of platelet (PLT) processing and storage conditions on HMGB1, sCD40L, and sCD62P protein levels in platelet concentrate supernatants (PCs). STUDY DESIGN/METHODS: PC supernatants (n = 3748) were collected by each international centre using identical centrifugation methods (n = 9) and tested centrally using the ELISA/Luminex platform. Apheresis versus the buffy coat (BC-PC) method, plasma storage versus PAS and RT storage versus cold (4°C) were investigated. We focused on PC preparation collecting samples during early (RT: day 1-3; cold: day 1-5) and late (RT: day 4-7; cold: day 7-10) storage time points. RESULTS: HMGB1, sCD40L, and sCD62P concentrations were similar during early storage periods, regardless of storage solution (BC-PC plasma and BC-PC PAS-E) or temperature. During storage and without PAS, sCD40L and CD62P in BC-PC supernatants increased significantly (+33% and +41%, respectively) depending on storage temperature (22 vs. 4°C). However, without PAS-E, levels decreased significantly (-31% and -20%, respectively), depending on storage temperature (22 vs. 4°C). Contrastingly, the processing method appeared to have greater impact on HMGB1 release versus storage duration. These data highlight increases in these parameters during storage and differences between preparation methods and storage temperatures. CONCLUSIONS: The HMGB1 release mechanism/intracellular pathways appear to differ from sCD62P and sCD40L. The extent to which these differences affect patient outcomes, particularly post-transfusion platelet increment and adverse events, warrants further investigation in clinical trials with various therapeutic indications.

DAMPS and complement activation in platelet concentrates that induce adverse reactions in patients.

BACKGROUND: Patients with severe thrombocytopenia due to bone marrow failure and after chemotherapy are still treated with platelet transfusions. Platelet concentrates (PC) are associated with a high incidence of adverse reactions (AR). Platelet-derived damage-associated molecular patterns (DAMPS) and complement were proposed to play a role in the pathology of AR. STUDY DESIGN AND METHODS: Single donor apheresis platelet concentrates (SDA PCs) were produced in a regional setting of the French Blood Establishment. After transfusion samples were collected from PC and possible AR in patients were recorded. Platelet activation markers, High mobility group box 1 (HMGB1) and complement activation products (CAP) were measured. The correlation between platelet activation, and HMGB1 and complement activation was analyzed. RESULTS: A total of 56 PC were included in the study. 30 PC induced no AR, and 26 induced AR (Febrile non-hemolytic transfusion reaction n = 16; Atypical Allergic Transfusion Reactions n = 11; hemodynamic instability n = 5) in the patients. The levels of P-selectin, sCD40L, HMGB1, C3b/c, and C4b/c were all significantly increased in PC that induced AR following transfusion in patients. Additionally, HMGB1, C3b/c, and C4b/c were positively correlated with P-selectin and sCD40L. CONCLUSION: In this study, we observed an association between HMGB1 and CAP and the incidence of AR. Furthermore, we demonstrated that both HMGB1 and complement activation were correlated to platelet activation.

Immunothrombosis and the Role of Platelets in Venous Thromboembolic Diseases.

Venous thromboembolism (VTE) is the third leading cardiovascular cause of death and is conventionally treated with anticoagulants that directly antagonize coagulation. However, recent data have demonstrated that also platelets play a crucial role in VTE pathophysiology. In the current review, we outline how platelets are involved during all stages of experimental venous thrombosis. Platelets mediate initiation of the disease by attaching to the vessel wall upon which they mediate leukocyte recruitment. This process is referred to as immunothrombosis, and within this novel concept inflammatory cells such as leukocytes and platelets directly drive the progression of VTE. In addition to their involvement in immunothrombosis, activated platelets can directly drive venous thrombosis by supporting coagulation and secreting procoagulant factors. Furthermore, fibrinolysis and vessel resolution are (partly) mediated by platelets. Finally, we summarize how conventional antiplatelet therapy can prevent experimental venous thrombosis and impacts (recurrent) VTE in humans.

CD8+ T cells mediate ultraviolet A-induced immunomodulation in a model of extracorporeal photochemotherapy.

Extracorporeal photochemotherapy (ECP) that takes advantage of the immunomodulatory effects of UV light has been extensively used for many years for the treatment of several T cell-mediated diseases, including graft-versus-host disease (GvHD) and systemic scleroderma. Immune mechanisms that lead to the establishment of T cell tolerance in ECP-treated patients remain poorly known. In this study, we have tested the effect of UV/psoralen-treated BM-derived dendritic cells, referred to as ECP-BMDCs on the outcome of an antigen-specific T cell-mediated reaction, that is, contact hypersensitivity (CHS), which is mediated by CD8+ effector T cells (CD8+ Teff ). The intravenous (i.v.) injection of antigen-pulsed ECP-BMDCs in recipient C57BL/6 mice induced specific CD8+ T cells endowed with immunomodulatory properties (referred to as CD8+ TECP ), which prevented the priming of CD8+ Teff and the development of CHS, independently of conventional CD4+ regulatory T cells. CD8+ TECP mediated tolerance by inhibiting the migration and functions of skin DC and subsequently the priming of CD8+ Teff . CD8+ TECP displayed none of the phenotypes of the usual CD8+ T regulatory cells described so far. Our results reveal an underestimated participation of CD8+ T cells to ECP-induced immunomodulation that could explain the therapeutic effects of ECP in T cell-mediated diseases.

Platelet-derived sCD40L: specific inflammatory marker for early-stage severe acute respiratory syndrome coronavirus 2 infection.

BACKGROUND: The SARS-CoV-2 virus is the causing agent of the Coronavirus disease 2019 (COVID-19) characterized by a huge pro-inflammatory response and coagulation disorders that may lead to for its severe forms, in organ failure or even death. As major players of thrombo-inflammation, platelets release large amounts of immunomodulatory molecules and regulate leukocyte and endothelial activity, which are both altered in COVID-19. Altogether, this makes platelets a very likely actor of the thrombo-inflammatory complications of COVID-19. Thus, we propose to identify a platelet inflammatory signature of severe COVID-19 specifically modulated throughout the course of the disease. METHODS: Luminex technology and enzyme-linked immunosorbent assay were used to assess plasma levels of platelet inflammatory markers in patients with severe acute respiratory syndrome coronavirus 2 infection on admission and for 14 days afterwards. RESULTS: In accordance with the observations of other teams, we evidence that the plasma levels of the platelet soluble (s)CD40L is significantly elevated in the early stages of the disease. Interestingly we observe that the plasma level of sCD40L decreases overtime while that of sCD62P increases significantly. CONCLUSIONS: Our data suggest that there is a platelet signature of inflammatory response to SARS-COv-2 infection which varies overtime and could serve as monitoring biomarkers of patient inflammatory state. CLINICAL TRIAL REGISTRATION NUMBER: 2020-A01100-39; title: Human Ab Response & immunoMONItoring of COVID-19 Patients, registration date: 05/25/2020; URL of the registry: https://clinicaltrials.gov/ct2/history/NCT04373200?V_5=View .

Detection of refractive photokeratectomy traces during eye banking: impossible with organ culture but possible with an active storage machine: case report.

The detection of corneas operated on for refractive surgery [LASIK or photorefractive keratectomy (PRK)] will become a major concern for eye banks in the coming years because this surgery is often forgotten during the interview with the deceased's relatives. We present here 2 corneas operated on with PKR and stored successively in organ culture (OC) and in the active storage machine (ASM) that restores intraocular pressure, restores the cornea to its original shape, respects transparency and incorporates non-invasive controls. The 2 corneas of a 49-year-old donor operated 17 years earlier by PRK for -2 and -3 diopters myopia were stored in OC for 14 days and then placed in ASM for 48 h. Thickness map and OCT topography were performed under the 2 storage conditions, histology and electron microscopy were then performed. Traces of PRK remained unnoticed in OC while they were evident in ASM with central epithelial anomaly, central thinning and flattening of central keratometry shown by OCT. Histology and ultrastructure confirmed the absence of Bowman's membrane in the center. By placing the cornea under physiological conditions, and in particular by triggering its deswelling and by restoring its natural curvature, the ASM allows effective detection of subtle refractive surgery traces like those present after PRK.

Platelet Innate Immune Receptors and TLRs: A Double-Edged Sword.

Platelets are hematopoietic cells whose main function has for a long time been considered to be the maintenance of vascular integrity. They have an essential role in the hemostatic response, but they also have functional capabilities that go far beyond it. This review will provide an overview of platelet functions. Indeed, stress signals may induce platelet apoptosis through proapoptotis or hemostasis receptors, necrosis, and even autophagy. Platelets also interact with immune cells and modulate immune responses in terms of activation, maturation, recruitment and cytokine secretion. This review will also show that platelets, thanks to their wide range of innate immune receptors, and in particular toll-like receptors, and can be considered sentinels actively participating in the immuno-surveillance of the body. We will discuss the diversity of platelet responses following the engagement of these receptors as well as the signaling pathways involved. Finally, we will show that while platelets contribute significantly, via their TLRs, to immune response and inflammation, these receptors also participate in the pathophysiological processes associated with various pathogens and diseases, including cancer and atherosclerosis.

Platelet depletion limits the severity but does not prevent the occurrence of experimental transfusion-related acute lung injury.

BACKGROUND: Transfusion-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 METHODS: In 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. RESULTS: Depletion 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. CONCLUSIONS: This study suggests that blood platelets are not critically required for TRALI induction, although they are to some extent involved in its pathophysiology.

Revisiting Platelets and Toll-Like Receptors (TLRs): At the Interface of Vascular Immunity and Thrombosis.

While platelet function has traditionally been described in the context of maintaining vascular integrity, recent evidence suggests that platelets can modulate inflammation in a much more sophisticated and nuanced manner than previously thought. Some aspects of this expanded repertoire of platelet function are mediated via expression of Toll-like receptors (TLRs). TLRs are a family of pattern recognition receptors that recognize pathogen-associated and damage-associated molecular patterns. Activation of these receptors is crucial for orchestrating and sustaining the inflammatory response to both types of danger signals. The TLR family consists of 10 known receptors, and there is at least some evidence that each of these are expressed on or within human platelets. This review presents the literature on TLR-mediated platelet activation for each of these receptors, and the existing understanding of platelet-TLR immune modulation. This review also highlights unresolved methodological issues that potentially contribute to some of the discrepancies within the literature, and we also suggest several recommendations to overcome these issues. Current understanding of TLR-mediated platelet responses in influenza, sepsis, transfusion-related injury and cardiovascular disease are discussed, and key outstanding research questions are highlighted. In summary, we provide a resource-a "researcher's toolkit"-for undertaking further research in the field of platelet-TLR biology.

Innovative corneal active storage machine for long-term eye banking.

Optimal ex vivo corneal storage in eye banks is crucial to increase both the number of corneas suitable for graft and their intrinsic quality, mainly the number of viable endothelial cells, which dictates graft survival in recipients. With both passive storage methods used worldwide (short-term cold storage in the United States, long-term organ culture in Europe), significant endothelial cell loss is inevitable. Here we show that, with an active storage machine, also called a bioreactor, which restores 2 fundamental physiological parameters, intraocular pressure and medium renewal, endothelial cell survival is improved by 23% compared with organ culture after 4 weeks' storage. Also observed in the bioreactor is a 4-fold higher expression of Na+ /K+ ATPase, which supports one of the major endothelial cell pumping functions. In addition, corneas remain thin and transparent, so they are suitable for surgery at any time. This new active eye banking method may help to reduce the severe global scarcity of donor corneas.

Platelet α-granules modulate the inflammatory response under systemic lipopolysaccharide injection in mice.

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 α-granules. Mutations in Nbeal2 cause gray platelet syndrome (GPS), characterized by the lack of platelet α-granules. This study aims to evaluate the immunological (proinflammatory) effects of platelet α-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 α-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.

Inhibition of the CD40/CD40L complex protects mice against ALI-induced pancreas degradation.

BACKGROUND: Acute 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. OBJECTIVES: This study focused on pancreas-associated injury development during experimental ALI pathogenesis and its limitation through CD40/CD40L complex inhibition. MATERIALS AND METHODS: An 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. RESULTS: ALI 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. CONCLUSION: This 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.

Platelet-derived extracellular vesicles convey mitochondrial DAMPs in platelet concentrates and their levels are associated with adverse reactions.

BACKGROUND: Whereas platelet transfusion is a common medical procedure, inflammation still occurs in a fraction of transfused individuals despite the absence of any apparent infectious agents. Platelets can shed membrane vesicles, called extracellular vesicles (EVs), some of which contain mitochondria (mito+EV). With its content of damage-associated molecular pattern (DAMP), the mitochondrion can stimulate the innate immune system. Mitochondrial DNA (mtDNA) is a recognized DAMP detected in the extracellular milieu in numerous inflammatory conditions and in platelet concentrates. We hypothesized that platelet-derived mitochondria encapsulated in EVs may represent a reservoir of mtDNA. STUDY DESIGN AND METHODS: Herein, we explored the implication of mito+EVs in the occurrence of mtDNA quantified in platelet concentrate supernatants that induced or did not induce transfusion adverse reactions. RESULTS: We observed that EVs were abundant in platelet concentrates, and platelet-derived mito+EVs were more abundant in platelet concentrates that induced adverse reactions. A significant correlation (rs = 0.73; p < 0.0001) between platelet-derived mito+EV levels and mtDNA concentrations was found. However, there was a nonsignificant correlation between the levels of EVs without mitochondria and mtDNA concentrations (rs = -0.11; p = 0.5112). The majority of the mtDNA was encapsulated into EVs. CONCLUSION: This study suggests that platelet-derived EVs, such as those that convey mitochondrial DAMPs, may be a useful biomarker for the prediction of potential risk of adverse transfusion reactions. Moreover, our work implies that investigations are necessary to determine whether there is a causal pathogenic role of mitochondrial DAMP encapsulated in EVs as opposed to mtDNA in solution.

Soluble CD40L and CD62P levels differ in single-donor apheresis platelet concentrates and buffy coat-derived pooled platelet concentrates.

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.

Influence of platelet preparation techniques on in vitro storage quality after psoralen-based photochemical treatment using new processing sets for triple-dose units.

BACKGROUND: The INTERCEPT Blood System (IBS) for platelets (PLTs) uses a combination of psoralen and ultraviolet-A light to inactivate pathogens that may contaminate PLT concentrates (PCs). However, no data are available on the quality of IBS-treated PLTs from different apheresis and buffy-coat PC preparation platforms using the new triple storage (TS) set. STUDY DESIGN AND METHODS: The objective of this study was to evaluate the TS set on three different preparation platforms compared with the large-volume (LV) set, as control. PLT in vitro metabolic and activation parameters were studied over 7 days. RESULTS: Several statistical differences are observed between the two sets, particularly for pH, oxygen pressure (pO2 ), carbonic gaz pressure (pCO2 ), and bicarbonate. The three different preparation techniques influence PLT parameters, and the difference is statistically significant for all the studied parameters, except for pCO2 . The TS set has the advantage of shorter compound adsorption device time, higher PLT recoveries, and less PLT activation. CONCLUSION: Results from the measured metabolic parameters and PLT variables obtained from PCs treated by LV and TS sets indicated good PLT function preservation up to 7 days of storage. The in vitro assessment results demonstrated acceptable PLT function for transfusion.