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15 p.-7 fig.-2 tab., C-type lectin-like receptor 2 (CLEC-2) plays a crucial role in different platelet-related physiological and pathological processes. It signals through a tyrosine kinase-mediated pathway that is highly dependent on the positive feedback exerted by the platelet-derived secondary mediators, adenosine diphosphate (ADP) and thromboxane A2 (TXA2). Here, we aimed to analyze the tyrosine phosphoproteome of platelets activated with the CLEC-2 agonist rhodocytin to identify relevant phosphorylated tyrosine residues (p-Tyr) and proteins involved in platelet activation downstream of this receptor. We identified 363 differentially p-Tyr residues, corresponding to the majority of proteins previously known to participate in CLEC-2 signaling and also novel ones, including adaptors (e.g., DAPP1, Dok1/3, CASS4, Nck1/2), kinases/phosphatases (e.g., FAK1, FES, FGR, JAK2, SHIP2), and membrane proteins (e.g., G6F, JAM-A, PECAM-1, TLT-1). To elucidate the contribution of ADP and TXA2 at different points of the CLEC-2 signaling cascade, we evaluated p-Tyr levels of residues identified in the analysis and known to be essential for the catalytic activity of kinases Syk(p-Tyr525+526) and Src(p-Tyr419), and for PLCγ2 activity (p-Tyr759). We demonstrated that Syk phosphorylation at Tyr525+526 also happens in the presence of ADP and TXA2 inhibitors, which is not the case for Src-pTyr419 and PLCγ2-pTyr759. Kinetics studies for the three phosphoproteins show some differences in the phosphorylation profile. Ca2+ mobilization assays confirmed the relevance of ADP and TXA2 for full CLEC-2-mediated platelet activation. The present study provides significant insights into the intracellular events that take place following CLEC-2 activation in platelets, contributing to elucidate in detail the CLEC-2 signalosome., This study was supported by the Spanish Ministryof Economy and Competitiveness (MINECO) [grant No. SAF2016-79662-R], co-funded by the European Regional Develop-ment Fund (ERDF); and the Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia [ED431C2018/21; predoctoral grant Plan I2C 2014; and CentroSingular de investigación de Galicia accreditation 2016-2019, ED431G/05], co-funded by the European Regional Development Fund (ERDF). The study also received funding from the European Union’s Horizon 2020 research andinnovation programme under the Marie Skłodowska-Curiegrant agreement No 766118. J.A.E. is supported by DeutscheForschungsgemeinschaft [DFG grant: EB177/13-1]

Lipid rafts are membrane microdomains that have been proposed to play an important role in several platelet-signalling cascades, including those mediated by the receptors Glycoprotein VI (GPVI), and C-type lectin domain family 1 member B (CLEC-2), both involved in thrombus formation. We have performed a LC-MS/MS proteomic analysis of lipid rafts isolated from platelets activated through GPVI and CLEC-2 as well as from resting platelets. Our aim was to determine the magnitude of changes in lipid rafts protein composition and to elucidate the relevance of these alterations in platelet function. A number of relevant signalling proteins were found enriched in lipid rafts following platelet activation (such as the tyrosine protein kinases Fyn, Lyn and Yes; the G proteins G(i) and G(z); and cAMP protein kinase). Interestingly, our results indicate that the relative enrichment of lipid rafts in these signalling proteins may not be a consequence of protein translocation to these domains upon platelet stimulation, but the result of a massive loss in cytoskeletal proteins after platelet activation. Thus, this study may help to better understand the effects of platelet activation in the reorganization of lipid rafts and set the basis for further proteomic studies of these membrane microdomains in platelets. Significance: We performed the first proteomic comparative analysis of lipid rafts- protein composition in platelets activated through GPVI and CLEC-2 receptors and in resting state. We identified a number of signalling proteins essential for platelet activation relatively enriched in platelets activated through both receptors, and we show that lipid rafts reorganization upon platelet activation leads to a loss in cytoskeletal proteins, highly associated to these domains in resting platelets., This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) [grant No. SAF2016-79662-R], co-funded by the European Regional Development Fund (ERDF); the Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia [predoctoral grant Plan I2C 2014; and Centro Singular de investigación de Galicia accreditation 2016–2019, ED431G/05; both co-funded by the ERDF]. J.A.E. is supported by Deutsche Forschungsgemeinschat [DFG grant: EB177/13-1].

Background: Clinical management of ischemic events and prevention of vascular disease is based on antiplatelet drugs. Given the relevance of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) as a candidate target in thrombosis, the main goal of the present study was to identify novel antiplatelet agents within the existing inhibitors blocking PI3K isoforms. Methods: We performed a biological evaluation of the pharmacological activity of PI3K inhibitors in platelets. The effect of the inhibitors was evaluated in intracellular calcium release and platelet functional assays, the latter including aggregation, adhesion, and viability assays. The in vivo drug antithrombotic potential was assessed in mice undergoing chemically induced arterial occlusion, and the associated hemorrhagic risk evaluated by measuring the tail bleeding time. Results: We show that PI3K Class IA inhibitors potently block calcium mobilization in human platelets. The PI3K p110δ inhibitor Idelalisib inhibits platelet aggregation mediated by ITAM receptors GPVI and CLEC-2, preferentially by the former. Moreover, Idelalisib also inhibits platelet adhesion and aggregation under shear and adhesion to collagen. Interestingly, an antithrombotic effect was observed in mice treated with Idelalisib, with mild bleeding effects at high doses of the drug. Conclusion: Idelalisib may have antiplatelet effects with minor bleeding effects, which provides a rationale to evaluate its antithrombotic efficacy in humans.

Obesity is one of the main health problems in industrialized countries. The contribution of multiple factors developed in obesity can hardly be modeled in vitro. In this context, the development of animal models mimicking human obesity could be essential. The aim of the present study was to compare platelets from a diet-induced obesity (DIO) rat model with their lean control group in order to elucidate platelet dysfunction mechanisms in obesity and correlate the results with previous data from morbid obese patients. In parallel, we also established a blood collection and platelet isolation methodology to study the DIO rat model at biochemical and functional level. Optimal blood collection was obtained from vena cava and platelet isolation was based on a serial of centrifugations avoiding platelet activation. Our results show that the DIO rat model simulate obesity pathologically since weight gain, fasting glucose and platelet counts are increased in obese rats. Interestingly, platelet levels of the active form of Src (pTyr419) showed a tendency to increase in DIO rats pointing towards a potential dysfunction in Src family kinases-related signalling pathways in obesity. Moreover, platelets from DIO rats adhere more to collagen compared with the control group, pointing towards Glycoprotein VI (GPVI) as one of the dysregulated receptors in obesity, in agreement with our recent studies in humans. These results confirm that obesity, in line with human studies, present a platelet dysregulation, and highlight the relevance of considering novel antithrombotic drug targets in these patients, such as GPVI.

Resumen El presente estudio muestra un caso clinico de reversion de una artrodesis con un implante total a una paciente de 63 anos que habia sido intervenida en dos ocasiones de artrodesis fallidas. La paciente presentaba dolor persistente a nivel de la articulacion de Chopart, asi como a nivel del maleolo externo, en especial durante la marcha, dolor a la palpacion directa a nivel de los ligamentos laterales del tobillo y dolor a nivel de articulacion astragalo-escafoidea y calcaneo-cuboidea cuando realizaba inversion forzada. En el presente articulo se introduce un metodo de tratamiento para revertir una artrodesis de la primera articulacion metatarso-falangica mediante la colocacion de un implante total tipo Toefit-Plus™ para devolver la movilidad de la articulacion. Se consiguio alivio del dolor con una movilidad de la primera articulacion metatarso-falangica dentro de limites normales, con un primer radio ligeramente insuficiente, siendo necesario un tratamiento posquirurgico con soportes plantares para mejorar la funcionalidad. En el examen clinico de rango de movimiento activo se lograron 40 de dorsiflexion, y en cuanto a la funcionalidad del extensor largo del primer dedo, volvio a su estado natural despues de la intervencion. El mayor conocimiento de las ventajas y desventajas de esta tecnica nos permitiria que mas pacientes pudieran verse favorecidos ante situaciones desfavorables con artrodesis metatarso-falangicas que no han dado el resultado esperado, por lo que es necesario profundizar en el estudio de mas casos.

In blood banks, platelets are stored until 7 days after a pathogen reduction technology (PRT) treatment, Mirasol® (vitamin B2 plus UVB light) in the present case. The storage time under these conditions may have an impact on platelets and their releasate leading to potential adverse reactions following transfusion to patients. The aim of this study was to analyze the proteome of extracellular vesicles generated by platelets at different storage days (2 and 7) to gain deeper information on the platelet concentrates state at those moments. EVs were isolated by a centrifugation-based approach and characterized by dynamic light scattering and transmission electron microscopy. Proteomic analysis was by LC-MS/MS and quantification by SWATH. In this way, 151 proteins were found up-regulated at day 7 of storage. This group includes CCL5 and Platelet Factor 4, chemokines with power to attract neutrophils and monocytes, which could generate transfusion adverse reactions. In addition, other glycoproteins and platelet activation markers were also found elevated at day 7. Proteins related to glycolysis and lactate production were found altered with high fold changes, showing a deregulation of platelet metabolism at day 7. The obtained results provide novel information about possible effects of platelet-derived EVs on transfusion adverse reactions. Significance We performed the first proteomic analysis of extracellular vesicles derived from platelets upon storage at different time points on blood bank conditions after Mirasol® treatment. We identified a high number of proteins related to platelet activation and platelet storage lesion that could have a role in possible transfusion adverse reactions.

Unwanted platelet activation is associated with numerous diseases, mainly thrombosis-related. In this context, proteomics has emerged as a novel tool with potential for drug target discovery and to scrutinize the effects of antiplatelet drugs. Areas covered: The present review presents the main findings of platelet proteomic studies to date in the context of drug target discovery and perspectives for the future ahead. It includes data and evidences obtained from literature searches on PubMed as well as commentaries derived from the authors' experience and opinions. Expert commentary: Platelet proteomics applied to drug target discovery is a young field. Recent studies have shown promising data, especially in the context of coronary artery disease. However, challenges remain such as establishing definitive guidelines for blood collection and platelet isolation, essential to guarantee data reproducibility. Recent advances in quantitative platelet proteomics should lead to novel studies with higher clinical impact in the near future.

Dilated cardiomyopathy (DCM) is a severe heart disease characterized by progressive ventricular dilation and impaired systolic function of the left ventricle. We recently identified a novel pathogenic mutation in the LMNA gene in a family affected by DCM showing sudden death background. We now aimed to identify potential biomarkers of disease status, as well as sudden death predictors, in members of this family. We analysed plasma samples from 14 family members carrying the mutation, four of which (with relevant clinical symptoms) were chosen for the proteomic analysis. Plasma samples from these four patients and from four sex- and age-matched healthy controls were processed for their enrichment in low- and medium-abundance proteins (ProteoMiner™) prior to proteomic analysis by 2D-DIGE and MS. 111 spots were found to be differentially regulated between mutation carriers and control groups, 83 of which were successfully identified by MS, corresponding to 41 different ORFs. Some proteins of interest were validated either by turbidimetry or western blot in family members and healthy controls. Actin, alpha-1-antytripsin, clusterin, vitamin-D binding protein and antithrombin-III showed increased levels in plasma from the diseased group. We suggest following these proteins as putative biomarkers for the evaluation of DCM status in LMNA mutation carriers. Biological significance We developed a proteomic analysis of plasma samples from a family showing history of dilated cardiomyopathy caused by a LMNA mutation, which may lead to premature death or cardiac transplant. We identified a number of proteins augmented in mutation carriers that could be followed as potential biomarkers for dilated cardiomyopathy on these patients.

Plasma-derived extracellular vesicles (EVs) have been extensively described as putative biomarkers in different diseases. Interestingly, increased levels of EVs subpopulations are well known to associate with obesity. The goal of this study is to identify EVs-derived biomarkers in plasma from obese patients in order to predict the development of pathological events associated with obesity. Samples are obtained from 22 obese patients and their lean-matched controls are divided into two cohorts: one for a 2D fluorescence difference gel electrophoresis (2D-DIGE)-based study, and the other one for a label free LC–MS/MS-based approach. EVs are isolated following a serial ultracentrifugation protocol. Twenty-two and 23 differentially regulated features are detected from 2D-DIGE and label free LC–MS/MS, respectively; most of them involve in the coagulation and complement cascades. Remarkably, there is an upregulation of complement C4, complement C3, and fibrinogen in obese patients following both approaches, the latter two also validated by 2D-western-blotting in an independent cohort. These results correlate with a proinflammatory and prothrombotic state of those individuals. On the other hand, a downregulation of adiponectin leading to an increased risk of suffering cardiovascular diseases has been shown. The results suggest the relevance of plasma-derived-EVs proteins as a source of potential biomarkers for the development of atherothrombotic events in obesity., This work was supported by the Spanish Ministry of Economy and Competitiveness; grant No. SAF2016-79662-R), co-funded by the European Regional Development Fund. Financial support from the Conseller ́ıa de Cultura, Educaci ́on e Ordenaci ́on Universitaria, Xunta de Galicia (Centro Singular de investigaci ́on de Galicia accreditation 2016–2019,ED431G/05), and the European Regional Development Fund is also grate-fully acknowledged. The Proteomics Laboratory CSIC/UAB is a member ofProteored, PRB2-ISCIII and is supported by Grant PT13/0001, of the PEI+D+i 2013–2016, funded by ISCIII and FEDER.