Background: Platelets are crucial immunomodulatory elements linking inflammatory and thrombotic processes. Platelet-leukocyte aggregates increase the pro-inflammatory functions of leukocytes causing the release of neutrophil extracellular traps (NETs). NETs and platelets activate each other promoting a prothrombotic phenotype. MiR-146a acts as a brake on inflammatory and immunological reactions. Our previous results showed the involvement of miR-146a in thrombo-inflammatory diseases by regulating NET formation.
Aims: To evaluate the role of miR-146a in platelet functionality and thrombosis.
Methods: Wild type (WT) and miR-146a-/- (KO) mice were evaluated for:
1) Tail bleeding (n=12/group);
2) Fibrinogen (Fg) binding and P-selectin exposure (P-Sel) after platelet activation (PAR4, CRP, and PMA) (n=4-7/group) by flow cytometry;
3) Platelet metabolism by Seahorse analyzer;
4) Pulmonary thromboembolism (PTE) by monitoring time to death (30min) (n=27 WT, n=30 KO). Lung obstruction was assessed by injecting Evans-Blue;
5) FeCl3 induced-arterial thrombosis (AT) by measuring blood flow occlusion time (OT) (n=17 WT, n=24 KO). NETs were quantified in AT by immunofluorescence [DNA/citrullinated-histone3 (citH3)] (n=10/group).
Results: Bleeding time was shorter in KO vs. WT mice (p=0.02). Fg binding and P-Sel exposure were higher in KO vs. WT platelets after activating with different concentrations of PAR4, CRP and PMA (Fig.1). Oxidative phosphorylation and glycolysis were also higher in unstimulated KO platelets (p< 0.01) and following PAR4 stimulation (Fig.2). KO mice succumbed earlier than WT after PTE induction (p=0.06). Obstruction of pulmonary circulation was higher in KO mice (p=0.01). OT was shorter in KO vs. WT mice (p=0.03) after AT induction. Moreover, thrombi extracted from KO mice showed more DNA/citH3 positive cells than WT (p< 0.01).
Conclusions: Platelets from KO mice are hyperreactive, which causes a prothrombotic phenotype that favors venous and arterial thrombosis. Increased platelet reactivity due in part to alterations in energy production profile could contribute to increase NET formation, supporting miR-146a involvement in immunothrombosis.
To cite this abstract in AMA style:Arroyo AB, Águila S, Fernández Pérez MP, de los Reyes-García AM, García Barberá N, Reguilón L, Rivera J, Vicente V, González Conejero R, Martínez C. MiR-146a Regulates Platelet Function and Thrombosis [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/mir-146a-regulates-platelet-function-and-thrombosis/. Accessed January 27, 2022.
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