Extracellular vesicles released by CD4+ T cells activate platelets

MARÍA ALBERTINA ROMANIUK; PAULA PEREZ; PEHUEN PEREYRA; MATIAS OSTROWSKI; GABRIEL DUETTE; JULIA RUBIONE

Melbourne

Congreso; ISTH 2019; 2019

International Society on thrombosis and haemostasis

Platelets and lymphocytes play important roles in inflammation. However, knowledge on the interaction between these cells and its consequences is limited. Extracellular Vesicles (EVs) carry bioactive lipids, miRNAs and proteins that can modulate target cell functions. Thus, EVs have emerged as a novel intercellular communication system with implications in diverse pathologies, such as cancer, infections and atherosclerosis.Study the effect of CD4+ T lymphocyte-derived EVs on platelet function.CD4+ T cells were purified and activated with anti-CD3/CD28 antibodies. After 48 h, EVs were obtained by differential ultracentrifugation, characterized by immunoblot and incubated with washed platelets. Platelet activation parameters were determined by microscopy, immunoblot, flow cytometry and aggregometry.EVs secreted by activated CD4+ T cells contained the canonical EV markers CD63 and CD81 and excluded the endoplasmic reticulum marker calnexin, indicating that our EV preparations were pure. EVs had a spherical shape and a diameter that ranged from 50 to 200 nm. Purified vesicles interacted with human washed platelets and induced hemostatic responses, such as αIIbβ3 integrin activation, platelet adhesion and spreading, aggregation and degranulation (CD63 exposure) in an extracellular calcium-dependent manner. Furthermore, CD4+ T cell derived EVs induced P-selectin exposure and the formation of platelet-PMN and platelet-monocyte mixed aggregates suggesting a pro-inflammatory role for this interaction. Finally, we demonstrate that the effect of EVs on platelets is specific for CD4+ T cells. Indeed, EVs purified from plasma and from the human mammary carcinoma cell line MCF-7 did not induce platelet activation.EVs released by activated CD4+ T cells promote platelet activation and leukocyte recruitment. We propose that this type of intercellular communication could participate in the development of inflammation, exacerbation of leukocyte activation, and intercellular adhesion and migration during the initial phases of vascular injury and the atherosclerotic disease.