Evaluation of Retinal Sensitivity in Complete Retinal-Pigment-Epithelium and Outer Retinal Atrophy (cRORA) Lesions in Intermediate Age-Related Macular Degeneration (iAMD) by High-Resolution Microperimetry.

: Lesions characterized as complete retinal pigment epithelium and outer retinal atrophy (cRORA) are linked to the progression of intermediate age-related macular degeneration (iAMD). However, the extent of functional impairment of such precursor lesions remains uncertain. : In this cross-sectional study, 4 participants (mean age ± standard deviation: 71.

Antagonistic Roles of Human Platelet Integrin αIIbβ3 and Chemokines in Regulating Neutrophil Activation and Fate on Arterial Thrombi Under Flow.

Background: Platelets and neutrophils are the first blood cells accumulating at sites of arterial thrombus formation, and both cell types contribute to the pathology of thrombotic events. We aimed to identify key interaction mechanisms between these cells using microfluidic approaches.

Methods: Whole-blood perfusion was performed over a collagen surface at arterial shear rate.

MAGT1 Deficiency Dysregulates Platelet Cation Homeostasis and Accelerates Arterial Thrombosis and Ischemic Stroke in Mice.

Background: MAGT1 (magnesium transporter 1) is a subunit of the oligosaccharide protein complex with thiol-disulfide oxidoreductase activity, supporting the process of N-glycosylation. MAGT1 deficiency was detected in human patients with X-linked immunodeficiency with magnesium defect syndrome and congenital disorders of glycosylation, resulting in decreased cation responses in lymphocytes, thereby inhibiting the immune response against viral infections. Curative hematopoietic stem cell transplantation of patients with X-linked immunodeficiency with magnesium defect causes fatal bleeding and thrombotic complications.

The Amino Acid Homoarginine Inhibits Atherogenesis by Modulating T-Cell Function.

Background: Amino acid metabolism is crucial for inflammatory processes during atherogenesis. The endogenous amino acid homoarginine is a robust biomarker for cardiovascular outcome and mortality with high levels being protective. However, the underlying mechanisms remain elusive.

Crystal Clots as Therapeutic Target in Cholesterol Crystal Embolism.

Rationale: Cholesterol crystal embolism can be a life-threatening complication of advanced atherosclerosis. Pathophysiology and molecular targets for treatment are largely unknown.

Objective: We aimed to develop a new animal model of cholesterol crystal embolism to dissect the molecular mechanisms of cholesterol crystal (CC)-driven arterial occlusion, tissue infarction, and organ failure.

Native, Intact Glucagon-Like Peptide 1 Is a Natural Suppressor of Thrombus Growth Under Physiological Flow Conditions.

Objective: In patients with diabetes mellitus, increased platelet reactivity predicts cardiac events. Limited evidence suggests that DPP-4 (dipeptidyl peptidase 4) influences platelets via GLP-1 (glucagon-like peptide 1)-dependent effects. Because DPP-4 inhibitors are frequently used in diabetes mellitus to improve the GLP-1-regulated glucose metabolism, we characterized the role of DPP-4 inhibition and of native intact versus DPP-4-cleaved GLP-1 on flow-dependent thrombus formation in mouse and human blood.

Multiparametric Model for Penumbral Flow Prediction in Acute Stroke.

Background And Purpose: Identification of salvageable penumbra tissue by dynamic susceptibility contrast magnetic resonance imaging is a valuable tool for acute stroke patient stratification for treatment. However, prior studies have not attempted to combine the different perfusion maps into a predictive model. In this study, we established a multiparametric perfusion imaging model and cross-validated it using positron emission tomography perfusion for detection of penumbral flow.

TMEM16F-Mediated Platelet Membrane Phospholipid Scrambling Is Critical for Hemostasis and Thrombosis but not Thromboinflammation in Mice-Brief Report.

Objective: It is known that both platelets and coagulation strongly influence infarct progression after ischemic stroke, but the mechanisms and their interplay are unknown. Our aim was to assess the contribution of the procoagulant platelet surface, and thus platelet-driven thrombin generation, to the progression of thromboinflammation in the ischemic brain.

Approach And Results: We present the characterization of a novel platelet and megakaryocyte-specific TMEM16F (anoctamin 6) knockout mouse.

Platelet CD40 Exacerbates Atherosclerosis by Transcellular Activation of Endothelial Cells and Leukocytes.

Objective: Beyond their eminent role in hemostasis and thrombosis, platelets are recognized as mediators of inflammation. Platelet cluster of differentiation 40 (CD40) ligand (CD40L and CD154) plays a key role in mediating platelet-induced inflammation in atherosclerosis. CD40, the receptor for CD40L, is present on platelets; however, the role of CD40 on this cell type is until now undefined.

Comparison of the 2 Most Popular Deconvolution Techniques for the Detection of Penumbral Flow in Acute Stroke.

Background And Purpose: Dynamic susceptibility-weighted contrast-enhanced (DSC) magnetic resonance imaging (MRI) is used to identify the tissue-at-risk in acute stroke, but the choice of optimal DSC postprocessing in the clinical setting remains a matter of debate. Using 15O-water positron emission tomography (PET), we validated the performance of 2 common deconvolution methods for DSC-MRI.

Methods: In (sub)acute stroke patients with consecutive MRI and PET imaging, DSC maps were calculated applying 2 deconvolution methods, standard and block-circulant single value decomposition.

Platelet CD40L Modulates Thrombus Growth Via Phosphatidylinositol 3-Kinase β, and Not Via CD40 and IκB Kinase α.

Objective: To investigate the roles and signaling pathways of CD40L and CD40 in platelet-platelet interactions and thrombus formation under conditions relevant for atherothrombosis.

Approach And Results: Platelets from mice prone to atherosclerosis lacking CD40L (Cd40lg(-/-)Apoe(-/-)) showed diminished αIIbβ3 activation and α-granule secretion in response to glycoprotein VI stimulation, whereas these responses of CD40-deficient platelets (Cd40(-/-)Apoe(-/-)) were not decreased. Using blood from Cd40lg(-/-)Apoe(-/-) and Cd40(-/-)Apoe(-/-) mice, the glycoprotein VI-dependent formation of dense thrombi was impaired on atherosclerotic plaque material or on collagen, in comparison with Apoe(-/-) blood.

Dual-specificity phosphatase 3 deficiency or inhibition limits platelet activation and arterial thrombosis.

Background: A limitation of current antiplatelet therapies is their inability to separate thrombotic events from bleeding occurrences. A better understanding of the molecular mechanisms leading to platelet activation is important for the development of improved therapies. Recently, protein tyrosine phosphatases have emerged as critical regulators of platelet function.

Factor XII regulates the pathological process of thrombus formation on ruptured plaques.

Objective: Atherothrombosis is the main cause of myocardial infarction and ischemic stroke. Although the extrinsic (tissue factor-factor VIIa [FVIIa]) pathway is considered as a major trigger of coagulation in atherothrombosis, the role of the intrinsic coagulation pathway via coagulation FXII herein is unknown. Here, we studied the roles of the extrinsic and intrinsic coagulation pathways in thrombus formation on atherosclerotic plaques both in vivo and ex vivo.

What can proteomics tell us about platelets?

More than 130 years ago, it was recognized that platelets are key mediators of hemostasis. Nowadays, it is established that platelets participate in additional physiological processes and contribute to the genesis and progression of cardiovascular diseases. Recent data indicate that the platelet proteome, defined as the complete set of expressed proteins, comprises >5000 proteins and is highly similar between different healthy individuals.

Supporting roles of platelet thrombospondin-1 and CD36 in thrombus formation on collagen.

Objective: Platelets abundantly express the membrane receptor CD36 and store its ligand thrombospondin-1 (TSP1) in the α-granules. We investigated whether released TSP1 can support platelet adhesion and thrombus formation via interaction with CD36.

Approach And Results: Mouse platelets deficient in CD36 showed reduced adhesion to TSP1 and subsequent phosphatidylserine expression.

Acid sphingomyelinase regulates platelet cell membrane scrambling, secretion, and thrombus formation.

Objective: Platelet activation is essential for primary hemostasis and acute thrombotic vascular occlusions. On activation, platelets release their prothrombotic granules and expose phosphatidylserine, thus fostering thrombin generation and thrombus formation. In other cell types, both degranulation and phosphatidylserine exposure are modified by sphingomyelinase-dependent formation of ceramide.