Sickle Cell Disease and Thromboembolism: New Insights on the Pathophysiology, Diagnosis, and Treatment.

Sickle cell disease (SCD) is a genetic hemoglobinopathy caused by the abnormal hemoglobin S (HbS) in red blood cells. As a result of its deoxygenation and polymerization, the properties and formation of red blood cells become altered, which ultimately leads to the development of SCD. Chronic inflammatory processes produced by hemolytic and vaso-occlusive episodes, define SCD clearly. These processes result in various effects, including organ damage and increased mortality in people suffering from the disease. Thromboembolism, a potentially fatal disease, is common in patients with sickle cell disease. Despite the known association between hypercoagulability and SCD, thromboembolism is often overlooked as a major complication of SCD. However, thromboembolism affects nearly one-quarter of adult patients and appears to be a risk factor for death in SCD. It has been well documented that in SCD, hemostatic alterations and thrombotic events are associated with endothelium and leukocyte activation. In SCD, inflammatory pathways play an important role in the activation of coagulation and the generation of platelet activation. Although among other mechanisms, it also involves the activation of tissue factors, the expression of adhesion molecules, and the stimulation of innate immune responses. So, mouse model studies may provide novel mechanistic pathways. These studies on mice models are yet to be applied to humans which will lead to the development of clinical lab treatments and therapeutic drugs. Additionally, SCD is a condition that responds favorably to biological treatments like gene therapy. SCD patients now have more potentially curative alternatives with recent developments in hematopoietic stem cell (HSC) transplantation and gene therapy platforms, including Lentiglobin vectors. In the present review, a discussion of the pathophysiology and thromboinflammation of sickle cell disease, along with its global burden in terms of both diagnosis and treatment, is presented.

Procoagulant Activity of Umbilical Cord-Derived Mesenchymal Stromal Cells' Extracellular Vesicles (MSC-EVs).

Many cell types, including cancer cells, release tissue factor (TF)-exposing extracellular vesicles (EVs). It is unknown whether MSC-EVs pose a thromboembolism risk due to TF expression. Knowing that MSCs express TF and are procoagulant, we hypothesize that MSC-EVs also might. Here, we examined the expression of TF and the procoagulant activity of MSC-EVs and the impact of EV isolation methods and cell culture expansion on EV yield, characterization, and potential risk using a design of experiments methodology. MSC-EVs were found to express TF and have procoagulant activity. Thus, when MSC-derived EVs are employed as a therapeutic agent, one might consider TF, procoagulant activity, and thromboembolism risk and take steps to prevent them.

Impairment of Anti-Aggregatory Responses to Nitric Oxide and Prostacyclin: Mechanisms and Clinical Implications in Cardiovascular Disease.

The propensity towards platelet-rich thrombus formation increases substantially during normal ageing, and this trend is mediated by decreases in platelet responsiveness to the anti-aggregatory nitric oxide (NO) and prostacyclin (PGI2) pathways. The impairment of soluble guanylate cyclase and adenylate cyclase-based signalling that is associated with oxidative stress represents the major mechanism of this loss of anti-aggregatory reactivity. Platelet desensitization to these autacoids represents an adverse prognostic marker in patients with ischemic heart disease and may contribute to increased thrombo-embolic risk in patients with heart failure. Patients with platelet resistance to PGI2 also are unresponsive to ADP receptor antagonist therapy. Apart from ischemia, diabetes and aortic valve disease are also associated with impaired anti-aggregatory homeostasis. This review examines the association of impaired platelet cyclic nucleotide (i.e., cGMP and cAMP) signalling with the emerging evidence of thromboembolic risk in cardiovascular diseases, and discusses the potential therapeutic strategies targeting this abnormality.

High Mobility Group Box 1 Protein in Cerebral Thromboemboli.

High-mobility group box 1 protein (HMGB1) is a damage-associated molecular pattern (DAMP) involved in neutrophil extracellular trap (NET) formation and thrombosis. NETs are regularly found in cerebral thromboemboli. We here analyzed associated HMGB1 expression in human thromboemboli retrieved via mechanical thrombectomy from 37 stroke patients with large vessel occlusion. HMGB1 was detected in all thromboemboli, accounting for 1.7% (IQR 0.6-6.2%) of the total thromboemboli area and was found to be colocalized with neutrophils and NETs and in spatial proximity to platelets. Correlation analysis revealed that the detection of HMGB1 was strongly related to the number of neutrophils (r = 0.58, p = 0.0002) and platelets (r = 0.51, p = 0.001). Our results demonstrate that HMGB1 is a substantial constituent of thromboemboli causing large vessel occlusion stroke.

Pseudoginsenoside-F11 ameliorates thromboembolic stroke injury in rats by reducing thromboinflammation.

Pseudoginsenoside-F11 (PF11), an ocotillol-type ginsenoside, has been reported to exert neuroprotective effects on ischemic stroke induced by permanent and transient middle cerebral artery occlusion in experimental animals. The aim of the present study was to investigate the effect of PF11 on thromboembolic stroke in rats and its possible mechanisms on thromboinflammation. PF11 (4, 12, 36 mg/kg) was injected intravenously (i.v.) once a day for 3 consecutive days to male Wistar rats followed by embolic middle cerebral artery occlusion (eMCAO). The results showed that PF11 significantly reduced the cerebral infarction volume, brain edema and neurological deficits induced by eMCAO. Meanwhile, the thromboinflammation in the ischemic hemisphere was observed at 24 h after eMCAO, as indicated by the increased number of microvascular thrombus and inflammatory response. Moreover, eMCAO resulted in the up-regulation of platelet glycoprotein Ibα (GPIbα) and VI (GPVI), as well as the activation of contact-kinin pathway. Notably, PF11 significantly reversed all these changes. Furthermore, PF11 prevented the eMCAO-induced loss of tight junction proteins and up-regulation of matrix metalloproteinase-9 (MMP-9), thus leading to the alleviation of blood-brain barrier (BBB) damage. In conclusion, the present study revealed that thromboinflammation was induced in the ischemic hemisphere of rats after eMCAO and PF11 exerted marked protective effects against thromboembolic stroke by attenuating thromboinflammation and preventing BBB damage. This research further identifies the potential therapeutic role of PF11 for ischemic stroke.

Expression of miR-93-5p as a Potential Predictor of the Severity of Chronic Thromboembolic Pulmonary Hypertension.

BACKGROUND: MicroRNAs (miRNAs) play an important role in the pathogenesis of chronic thromboembolic pulmonary hypertension (CTEPH). However, the potential correlation between miRNA expression and the severity of CTEPH remains unclear. Our previous study indicated that miRNAs hsa-let-7b-3p, hsa-miR-17-5p, hsa-miR-106b-5p, hsa-miR-3202, hsa-miR-665, and hsa-miR-93-5p are closely involved in CTEPH. This study assessed the associations between the expression levels of these miRNAs and clinical parameters in CTEPH patients. METHODS: A total of eight CTEPH patients and eight healthy adults as a reference group were included, and clinical data including total protein (TP), albumin (Alb), lactate dehydrogenase (LDH), hydroxybutyrate dehydrogenase (HBDH), uric acid (UA), and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were collected. Right heart catheterization was conducted to obtain hemodynamic data including cardiac index (CI). The expression levels of let-7b-3p, miR-17-5p, miR-106b-5p, miR-3202, miR-665, and miR-93-5p were measured by quantitative real-time PCR (qPCR). Correlation analysis was applied to estimate the associations between miRNA expression levels and clinical parameters in CTEPH patients. RESULTS: Serum TP and Alb levels were decreased, while LDH, HBDH, and UA levels were increased in CTEPH patients compared with the reference group (P < 0.05). miR-3202 and miR-665 were upregulated, whereas let-7b-3p, miR-17-5p, miR-106b-5p, and miR-93-5p were downregulated in CTEPH patients relative to the reference group (P < 0.05). miR-93-5p expression was positively correlated with NT-proBNP level and negatively correlated with CI (P < 0.05). Moreover, let-7b-3p tended to be positively correlated with mean pulmonary arterial pressure. CONCLUSIONS: miR-93-5p expression was associated with the severity of CTEPH and could act as a potential predictor of high-risk CTEPH.

Protein network analyses of pulmonary endothelial cells in chronic thromboembolic pulmonary hypertension.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a vascular disease characterized by the presence of organized thromboembolic material in pulmonary arteries leading to increased vascular resistance, heart failure and death. Dysfunction of endothelial cells is involved in CTEPH. The present study describes for the first time the molecular processes underlying endothelial dysfunction in the development of the CTEPH. The advanced analytical approach and the protein network analyses of patient derived CTEPH endothelial cells allowed the quantitation of 3258 proteins. The 673 differentially regulated proteins were associated with functional and disease protein network modules. The protein network analyses resulted in the characterization of dysregulated pathways associated with endothelial dysfunction, such as mitochondrial dysfunction, oxidative phosphorylation, sirtuin signaling, inflammatory response, oxidative stress and fatty acid metabolism related pathways. In addition, the quantification of advanced oxidation protein products, total protein carbonyl content, and intracellular reactive oxygen species resulted increased attesting the dysregulation of oxidative stress response. In conclusion this is the first quantitative study to highlight the involvement of endothelial dysfunction in CTEPH using patient samples and by network medicine approach.

Carboxypeptidase U (CPU, TAFIa, CPB2) in Thromboembolic Disease: What Do We Know Three Decades after Its Discovery?

Procarboxypeptidase U (proCPU, TAFI, proCPB2) is a basic carboxypeptidase zymogen that is converted by thrombin(-thrombomodulin) or plasmin into the active carboxypeptidase U (CPU, TAFIa, CPB2), a potent attenuator of fibrinolysis. As CPU forms a molecular link between coagulation and fibrinolysis, the development of CPU inhibitors as profibrinolytic agents constitutes an attractive new concept to improve endogenous fibrinolysis or to increase the efficacy of thrombolytic therapy in thromboembolic diseases. Furthermore, extensive research has been conducted on the in vivo role of CPU in (the acute phase of) thromboembolic disease, as well as on the hypothesis that high proCPU levels and the Thr/Ile325 polymorphism may cause a thrombotic predisposition. In this paper, an overview is given of the methods available for measuring proCPU, CPU, and inactivated CPU (CPUi), together with a summary of the clinical data generated so far, ranging from the current knowledge on proCPU concentrations and polymorphisms as potential thromboembolic risk factors to the positioning of different CPU forms (proCPU, CPU, and CPUi) as diagnostic markers for thromboembolic disease, and the potential benefit of pharmacological inhibition of the CPU pathway.

Arterial thrombo-embolic events in cardiac amyloidosis: a look beyond atrial fibrillation.

BACKGROUND: Intracardiac thrombosis is reported to occur frequently in cardiac amyloidosis (CA). However, data regarding arterial thrombo-embolic events (AEs) in CA are limited. We aimed at assessing prevalence, clinical characteristics and predictors of AEs in a large multicentric CA cohort. METHODS AND RESULTS: Four-hundred-six consecutive CA patients (134 AL, 73 ATTRm and 199 ATTRwt) from 5 Italian referral centres were retrospectively evaluated and followed-up for a median time of 19 months. Thirty-one patients (7.6%) suffered from an AE, of whom 10 (32.2%) were in sinus rhythm and had no history of AF. There were no significant differences in terms of age, gender and type of CA between patients with or without AEs. Fourteen (7.6%) of 185 patients on anticoagulation had an AE despite therapy. Anticoagulation therapy did not appear to fully protect from the risk of events (HR 1.23, 95%CI 0.52-2.92, p = .64). The only predictor of AEs, in particular among CA patients in sinus rhythm, was a CHA2DS2-VASC score ≥ 3 (HR 2.84, 95%CI 1.02-7.92, p = .05 in overall population; HR 10.13, 95%CI 1.12-91.19, p = .04 in patients in sinus rhythm). CONCLUSIONS: In our large, multicentric, real-world cohort, prevalence and incidence rate of AEs was high. A consistent proportion of events occurred despite anticoagulation therapy or in patients in sinus rhythm. A higher CHA2DS2-VASc score might identify patients at risk of AEs also among those in sinus rhythm.

Perils of Antithrombotic Transitions: Effect of Oral Factor Xa Inhibitors on the Heparin Antifactor Xa Assay.

BACKGROUND: Oral factor Xa inhibitors (OFXais) may interfere with the heparin antifactor Xa (antiXa) assay. The best method to measure heparin activity during the transition from an OFXai to intravenous (IV) unfractionated heparin (UFH) remains unknown. This study aimed to assess the safety and effectiveness of transitioning from an OFXai to UFH. METHODS: A retrospective analysis was conducted of patients with supratherapeutic antiXa levels on UFH who received either apixaban or rivaroxaban within 72 hours before UFH initiation at NYU Langone Health. The primary objective was to identify the incidence of interference on the heparin antiXa assay due to OFXai exposure in the previous 72 hours. The secondary outcomes included the indication for transition to UFH and the rate of thromboembolic and bleeding events. RESULTS: A total of 93 patients with supratherapeutic antiXa activity levels with prior OFXai use were reviewed. Moderate renal impairment, defined as creatinine clearance less than 49 mL/min, was present in 67 (72%) patients. The primary indication for transition from OFXai to UFH was in anticipation for a procedure, and it occurred in 37 (40%) patients. There were 3 major bleeding events and 3 clinically relevant nonmajor bleeding events. No thromboembolic events occurred. CONCLUSIONS: This study assessed the prevalence of supratherapeutic antiXa levels and clinical outcomes during the transition from OFXais to UFH. Health care systems should develop guidelines to assist clinicians in monitoring antiXa activity in patients undergoing a transition from an OFXai to UFH. It is also important to assess the patient's underlying thromboembolic and bleeding risks.

Altered platelet proteome in lupus anticoagulant (LA)-positive patients-protein disulfide isomerase and NETosis as new players in LA-related thrombosis.

Patients with antiphospholipid syndrome (APS) are at high risk of developing venous and arterial thromboembolism (TE). The role of platelets in the pathogenesis of these prothrombotic conditions is not yet fully understood. The aim of this study was to gain mechanistic insights into the role of platelets in APS by comparing the platelet proteome between lupus anticoagulant (LA)-positive patients with (LA+ TE+) and without a history of TE (LA+ TE-) and healthy controls. The platelet proteome of 47 patients with LA, 31 with a history of TE and 16 without thrombotic history, and 47 healthy controls was analyzed by two-dimensional differential in-gel electrophoresis and mass spectrometry to identify disease-related proteins. Afterward, selected LA-related platelet proteins were validated by western blot and ELISA. Alterations of 25 proteins were observed between the study groups. STRING pathway analysis showed that LA-related protein profiles were involved in platelet activation, aggregation, and degranulation. For example, protein disulfide isomerase family members, enzymes that promote thrombosis, were upregulated in platelets and plasma of LA+ TE+ patients. Leukocyte elastase inhibitor (SERPINB1), an antagonist of neutrophil extracellular trap (NET) formation, was decreased in platelets of LA+ TE+ patients compared to healthy controls. Additionally, citrullinated histone H3, a NET-specific marker, was increased in plasma of LA+ TE+ patients. These findings suggest that decreased platelet SERPINB1 levels favor prothrombotic NETosis, especially in LA+ TE+ patients. Our findings reveal protein abundance changes connected to altered platelet function in LA-positive patients, thus suggesting a pathogenic role of platelets in thrombotic complications in APS.

Proteomic Analyses of Endarterectomized Tissues from Patients with Chronic Thromboembolic Pulmonary Hypertension.

BACKGROUND: The pathogenesis of chronic thromboembolic pulmonary hypertension (CTEPH) is largely unknown. Proteomics offers an approach to overview the molecular activities and signal transduction pathways involved in specific disease processes. OBJECTIVES: In this study, the expression of proteins in endarterectomized tissues from patients with CTEPH was investigated in a novel strategy to explore the pathophysiology of this disease. METHODS: We used the iTRAQ (isobaric tag for relative and absolute quantitation) approach combined with a Thermo Scientific Q Exactive MS analysis to compare the protein profiles in endarterectomized tissues from CTEPH patients and that of the control samples (mixture of cultured human pulmonary artery endothelial cells, human pulmonary artery smooth muscle cells, and human pulmonary fibroblasts). GO and KEGG analyses were performed to understand the functional classification and molecular activities of all the tissue-specific proteins, and the involved signal transduction pathways. RESULTS: Six hundred and seventy-nine tissue-specific proteins were detected. Bioinformatic analysis showed that the major biological processes involving these proteins were: response to wounding, defense response, acute inflammatory response, immune response, complement activation, and blood coagulation. The main pathways involved were: complement and coagulation cascade, systemic lupus erythematosus, extracellular matrix-receptor interaction, cell adhesion molecules, FcεRI signaling, and leukocyte transendothelial migration. CONCLUSIONS: The present study revealed that immune and defense response might play an important role in CTEPH.

Platelet thrombus formation in eHUS is prevented by anti-MBL2.

E. coli associated Hemolytic Uremic Syndrome (epidemic hemolytic uremic syndrome, eHUS) caused by Shiga toxin-producing bacteria is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and acute kidney injury that cause acute renal failure in up to 65% of affected patients. We hypothesized that the mannose-binding lectin (MBL) pathway of complement activation plays an important role in human eHUS, as we previously demonstrated that injection of Shiga Toxin-2 (Stx-2) led to fibrin deposition in mouse glomeruli that was blocked by co-injection of the anti-MBL-2 antibody 3F8. However, the markers of platelet thrombosis in affected mouse glomeruli were not delineated. To investigate the effect of 3F8 on markers of platelet thrombosis, we used kidney sections from our mouse model (MBL-2+/+ Mbl-A/C-/-; MBL2 KI mouse). Mice in the control group received PBS, while mice in a second group received Stx-2, and those in a third group received 3F8 and Stx-2. Using double immunofluorescence (IF) followed by digital image analysis, kidney sections were stained for fibrin(ogen) and CD41 (marker for platelets), von-Willebrand factor (marker for endothelial cells and platelets), and podocin (marker for podocytes). Electron microscopy (EM) was performed on ultrathin sections from mice and human with HUS. Injection of Stx-2 resulted in an increase of both fibrin and platelets in glomeruli, while administration of 3F8 with Stx-2 reduced both platelet and fibrin to control levels. EM studies confirmed that CD41-positive objects observed by IF were platelets. The increases in platelet number and fibrin levels by injection of Stx-2 are consistent with the generation of platelet-fibrin thrombi that were prevented by 3F8.

Factors associated to adequate time in therapeutic range with oral vitamin K antagonists in Tunisia.

INTRODUCTION:   The quality of chronic anticoagulation and predictor factors of poor anticoagulant control in patients under acenocoumarol were unknown in North Africa. METHODS: It is an observational study, carried out between November 2015 and November 30, 2016. The international normalized ratio (INR) values were prospectively obtained, and TTR was calculated using the Rosendaal method. RESULTS: Overall, 215 patients were included in this study, with a mean age of 63±0,8 years. The prevalence of poor anticoagulation control was 78.1%; 95% CI [72.2-83.2] (168 patients with TTR less than 65%). The median TTR with the Rosendaal method was 44.4%. After multivariate adjustment, variables significantly associated with adequate anticoagulation level were: history of ischemic stroke (Adjusted OR equal to 4.3, 95% CI: 1.4-12.9), associated prescription of antiplatelet therapy (Adjusted OR equal to 3.5, 95% CI: 1.1-11.2), daily prescribed dose of coumarins less than 6 mg (Adjusted OR equal to 6.4, 95% CI: 1.1- 36) and lower risk of bleeding assessed as HAS-BLED score (Adjusted OR: 0.5, 95% CI: 0.3-0.8). CONCLUSION: The quality of anticoagulation management with VKA among outpatients who received acenocoumarol was suboptimal. Strategies should be undertaken by clinicians and patients to improve the quality of anticoagulation, to address challenges to adverse cardiovascular outcomes in individuals treated with chronic anticoagulation.

Radiation dosimetry of [18F]GP1 for imaging activated glycoprotein IIb/IIIa receptors with positron emission tomography in patients with acute thromboembolism.

PURPOSE: 4-(3S)-3-[5-(2-[18F]-fluoroethoxy)pyridin-3-yl]-3-[({(3R)-1-[3-(piperidin-4-yl)propanoyl]-piperidin-3-yl}carbonyl)amino]propanoic acid ([18F]GP1) is a radiotracer developed for targeted imaging of activated platelet glycoprotein IIb/IIIa receptors with positron emission tomography/computed tomography (PET/CT) in acute thromboembolism. We evaluated here radiation dosimetry of [18F]GP1 in humans. PROCEDURES: We studied 30 subjects (10 with deep vein thrombosis, 10 with pulmonary embolism, and 10 with arterial thromboembolism) who had signs or symptoms of acute thromboembolism, and were confirmed to have thromboembolic foci by imaging studies. Dynamic whole-body PET/CT images were acquired for up to 140 min after injection of 250 MBq of [18F]GP1. Radiation absorbed dose and effective dose were calculated using the OLINDA/EXM software. RESULTS: [18F]GP1 PET images showed high initial uptake of the tracer in the heart, spleen, kidney, and liver. [18F]GP1 activity was cleared by hepatobiliary and urinary excretion. The organ receiving the highest radiation absorbed dose (mGy/MBq) was the urinary bladder (0.0884 ±â€¯0.0458), followed by upper large intestine (0.0498 ±â€¯0.0189), small intestine (0.0454 ±â€¯0.0166), and kidneys (0.0350 ±â€¯0.0231). The effective dose (mSv/MBq) was 0.0212 ±â€¯0.0027 (ICRP 103). ED was not significantly different between the three disease groups (p = 0.94). A 45-minute voiding reduced the urinary bladder wall radiation dose to 0.0495 ±â€¯0.0140 mGy/MBq, and effective dose (ICRP 103) to 0.0186 ±â€¯0.0030. CONCLUSIONS: [18F]GP1 has favorable radiation dosimetry profile for clinical PET/CT imaging. The ED is comparable to commonly used 18F PET tracers.

Correlations of coagulation indexes and inflammatory changes with the prognosis of lung cancer complicated with thromboembolic disease.

PURPOSE: To investigate the correlations of coagulation indexes and inflammatory changes with the prognosis of lung cancer (LC) patients complicated with thromboembolic (TE) disease. METHODS: A total of 84 LC patients complicated with TE disease admitted to hospital from January 2010 to January 2016 were enrolled in this study and their clinical data were retrospectively analyzed. A 2-year post-treatment follow-up was carried out. According to the prognosis, patients were divided into 2 groups as dead group (n=25) and alive group (n=59). The coagulation indexes and inflammatory factor levels before low-molecular weight heparin (LMWH) treatment and on the 1st, 3rd, and 7th day after treatment were compared between the two groups. Their relations with the prognosis of patients were analyzed using Pearson method. RESULTS: No statistically significant difference was found in the prothrombin time (PT), levels of Fibrinogen (FIB), D-Dimer (D-D), Interleukin-6 (IL-6) and Procalcitonin (PCT), and activated partial thromboplastin time (APTT) before treatment between the two groups (p>0.05). The PT and levels of FIB, D-D, IL-6, and PCT on the 1st, 3rd, and 7th day after treatment were significantly increased in the dead group compared to those in the alive group, while the APTT was remarkably shortened. Moreover, the PT was gradually prolonged and FIB, D-D, IL-6 and PCT levels were increased in the dead group , but the APTT was gradually shortened over time (p<0.05). The poor prognosis of LC patients complicated with TE disease was positively correlated with PT, FIB, D-D, IL-6 and PCT, but negatively correlated with APTT (p<0.05). CONCLUSION: The poor prognosis of LC complicated with TE disease has positive correlations with PT, FIB, D-D, IL-6 and PCT, and a negative association with APTT, providing a certain reference as a prognostic value in the diagnosis and treatment.

Inactivation of endothelial adenosine A2A receptors protects mice from cerebral ischaemia-induced brain injury.

BACKGROUND AND PURPOSE: Inactivation of the gene for adenosine A2A receptors (ADORA2A for humans and Adora2a for rodents) protects against brain injury in experimental stroke. However, the cell-specific pathogenic effects of A2A receptors in thromboembolic stroke and the underlying mechanisms remain undefined. Here, we tested the hypothesis that inhibition of endothelial A2A receptors after thromboembolic stroke improves post-stroke outcomes via down-regulation of inflammation. EXPERIMENTAL APPROACH: Thromboembolic stroke was induced by embolic middle cerebral artery occlusion in mice. Post-stroke outcomes were determined with neurological deficit scoring, infarct volume, inflammatory marker expression, brain leukocyte infiltration, blood-brain barrier (BBB) leakage, and oedema assessment. Anti-inflammatory effects of silencing the gene for A2A receptors or pharmacological antagonism of these receptors were assessed in vitro. KEY RESULTS: Thromboembolic stroke induced Adora2a expression in the brain. Mice globally deficient in Adora2a (Adora2a-/- ) were resistant to stroke injury. Mice specifically deficient in endothelial Adora2a (Adora2aΔVEC ) showed reduced leukocyte infiltration, BBB leakage, and oedema after stroke, along with attenuated downstream proinflammatory markers, both in vivo and in vitro. The A2A receptor antagonist, KW 6002, also reduced brain injury and inflammation after stroke. Inactivation of ADORA2A inhibited endothelial inflammation via suppression of the NLRP3 inflammasome, down-regulating cleaved caspase 1 and IL-1ß expression. CONCLUSIONS AND IMPLICATIONS: Specific inactivation of endothelial A2A receptors mitigated ischaemic brain injury and improved post-stroke outcomes, at least partly, through anti-inflammatory effects via blockade of NLRP3 inflammasome activity. Our findings may open new approaches to vascular protection after ischaemic stroke.

Changes in hemostasis parameters in nonfatal methicillin-sensitive Staphylococcus aureus bacteremia complicated by endocarditis or thromboembolic events: a prospective gender-age adjusted cohort study.

The aim of this study was to examine the changes in hemostasis parameters in endocarditis and thromboembolic events in nonfatal methicillin-sensitive Staphylococcus aureus bacteremia (MS-SAB) - a topic not evaluated previously. In total, 155 patients were recruited and were categorized according to the presence of endocarditis or thromboembolic events with gender-age adjusted controls. Patients who deceased within 90 days or patients not chosen as controls were excluded. SAB management was supervised by an infectious disease specialist. Patients with endocarditis (N = 21), compared to controls (N = 21), presented lower antithrombin III at day 4 (p < 0.05), elevated antithrombin III at day 90 (p < 0.01), prolonged activated partial thromboplastin time at days 4 and 10 (p < 0.05), and enhanced thrombin-antithrombin complex at day 4 (p < 0.01). Thromboembolic events (N = 8), compared to controls (N = 34), significantly increased thrombin-antithrombin complex at day 4 (p < 0.05). In receiver operating characteristic analysis, the changes in these hemostasis parameters at day 4 predicted endocarditis and thromboembolic events (p < 0.05). No differences in hemoglobin, thrombocyte, prothrombin fragment, thrombin time, factor VIII, D-dimer or fibrinogen levels were observed between cases and controls. The results suggest that nonfatal MS-SAB patients present marginal hemostasis parameter changes that, however, may have predictability for endocarditis or thromboembolic events. Larger studies are needed to further assess the connection of hemostasis to complications in SAB.