Background: The interplay between platelets and fibrinogen is the cornerstone of thrombus formation. Integrin αIIbβ3 is the main platelet adhesion receptor for fibrinogen and mediates an outside-in signal upon ligand binding that reinforces platelet activation. In addition, FcγRIIA and glycoprotein VI (GPVI) contribute to platelet activation on fibrinogen, thereby participating in thrombus growth and stability. To date, the relative importance of these two immunoreceptor tyrosine-based activation motif-bearing receptors in these processes remains unknown.
Objective: The aim of this study was to evaluate the relative contributions of FcγRIIA and GPVI to platelet activation on fibrinogen and subsequent thrombus growth and stability.
Methods: We evaluated human and mouse platelet adhesion to fibrinogen in static assays and a flow-based approach to evaluate the contribution of FcγRIIA and GPVI to thrombus growth and stability.
Results: We first confirmed that integrin αIIbβ3 is the key receptor supporting platelet adhesion and spreading on fibrinogen. Using human platelets treated with pharmacological blocking agents and transgenic mouse platelets expressing human receptors, data indicate that GPVI, but not FcγRIIA, plays a prominent role in platelet activation on fibrinogen. Moreover, using a flow-based assay, we observed that blockade of GPVI with 1G5, but not FcγRIIA with IV.3, prevents thrombus growth. Finally, we observed that 1G5, but not IV.3, promotes the disaggregation of thrombi formed on collagen in vitro.
Conclusion: This study provides evidence that GPVI, but not FcγRIIA, induces platelet activation and spreading on fibrinogen, and promotes thrombus buildup and stability.
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http://dx.doi.org/10.1002/rth2.12551 | DOI Listing |
Thromb Haemost
January 2025
Hemostasis and Erythropathology Laboratory, Hematopathology, Pathology Department, Centre de Diagnòstic Biomèdic (CDB), Hospital Clínic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona, Spain.
Background: V617F-mutated myeloproliferative neoplasms (MPN) exhibit abnormal proliferation of bone marrow progenitors and increased risk of thrombosis, specifically in splanchnic veins (SVT). The contribution of the endothelium to the development of the prothrombotic phenotype was explored.
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J Tradit Complement Med
January 2025
National Research Institute of Chinese Medicine, Ministry of Health and Welfare, Taipei City, 112026, Taiwan.
Amidst growing concerns over COVID-19 aftereffects like fatigue and cognitive issues, NRICM101, a traditional Chinese medicine, has shown promise. Used by over 2 million people globally, it notably reduces hospitalizations and intubations in COVID-19 patients. To explore whether NRICM101 could combat COVID-19 brain fog, we tested NRICM101 on hACE2 transgenic mice administered the S1 protein of SARS-CoV-2, aiming to mitigate S1-induced cognitive issues by measuring animal behaviors, immunohistochemistry (IHC) staining, and next-generation sequencing (NGS) analysis.
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January 2025
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Chungnam National University School of Medicine, Chungnam National University Hospital, 282 Munhwa-Ro, Jung-Gu, Daejeon, 35015, Republic of Korea.
Background: Interleukin-6 (IL-6) plays a central role in sepsis-induced cytokine storm involving immune hyperactivation and early neutrophil activation. Programmed death protein-1 (PD-1) is associated with sepsis-induced immunosuppression and lymphocyte apoptosis. However, the effects of simultaneous blockade of IL-6 and PD-1 in a murine sepsis model are not well understood.
View Article and Find Full Text PDFMethods Mol Biol
January 2025
Division of Hemostasis and Thrombosis, Department of Medicine, BIDMC, Harvard Medical School, Boston, MA, USA.
The actin cytoskeleton serves an important, but poorly characterized, role in controlling granule exocytosis. The dynamic nature of actin remodeling allows it to act both as a barrier to prevent indiscriminate granule release and as a facilitator of membrane fusion. In its capacity to promote exocytosis, filamentous actin binds to components of the exocytotic machinery through actin binding proteins, but also through direct interactions with SNAREs.
View Article and Find Full Text PDFNat Commun
January 2025
Division of Virology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
Microthrombus formation is associated with COVID-19 severity; however, the detailed mechanism remains unclear. In this study, we investigated mouse models with severe pneumonia caused by SARS-CoV-2 infection by using our in vivo two-photon imaging system. In the lungs of SARS-CoV-2-infected mice, increased expression of adhesion molecules in intravascular neutrophils prolonged adhesion time to the vessel wall, resulting in platelet aggregation and impaired lung perfusion.
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