Expression and functionality of Toll-like receptor 3 in the megakaryocytic lineage
Background: In addition to their key role in hemostasis, platelets and megakaryocytes regulate immune and inflammatory responses, in part through their expression of Toll-like receptors (TLRs). Among the TLRs, TLR3 recognizes dsRNA associated with viral infection. Thrombocytopenia is a frequent comp...
| Autores: | , , , , , , , |
|---|---|
| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2015 |
| País: | Argentina |
| Recursos: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/38495 |
| Acesso em linha: | http://hdl.handle.net/11336/38495 |
| Access Level: | acceso abierto |
| Palavra-chave: | Interferon-Beta Megakaryocytes Nf-Kappa B Platelets Toll-Like Receptor&Nbsp;3 https://purl.org/becyt/ford/3.1 https://purl.org/becyt/ford/3 |
| Resumo: | Background: In addition to their key role in hemostasis, platelets and megakaryocytes regulate immune and inflammatory responses, in part through their expression of Toll-like receptors (TLRs). Among the TLRs, TLR3 recognizes dsRNA associated with viral infection. Thrombocytopenia is a frequent complication of viral infection. However, the expression and functionality of TLR3 in megakaryocytes and platelets is not yet well understood. Objective: To study the expression and functionality of TLR3 in the megakaryocytic lineage. Methods and results: RT-PCR, flow cytometric and immunofluorescence assays showed that TLR3 is expressed in CD34+ cells, megakaryocytes, and platelets. Immunoblotting assays showed that stimulation of megakaryocytes with two synthetic agonists of TLR3, Poly(I:C) and Poly(A:U), activated the nuclear factor-κB (NF-κB), phosphoinositide 3-kinase (PI3K)/Akt, extracellular signal-related kinase (ERK)1/2 and p38 pathways. TLR3-megakaryocyte activation resulted in reduced platelet production in vitro and interferon-β release through the PI3K-Akt and NF-κB signaling pathways. TLR3 ligands potentiated the aggregation mediated by classic platelet agonists. This effect was also observed for ATP release, but not for P-selectin or CD40L membrane exposure, indicating that TLR3 activation was not involved in α-granule release. In addition, TLR3 agonists induced activation of the NF-κB, PI3K-Akt and ERK1/2 pathways in platelets. Reductions in platelet production and platelet fibrinogen binding mediated by Poly(I:C) or Poly(A:U) were prevented by the presence of an inhibitor of the TLR3-dsRNA complex. Conclusions: Our findings indicate that functional TLR3 is expressed in CD34+ cells, megakaryocytes, and platelets, and suggest a potential role for this receptor in the megakaryopoiesis/thrombopoiesis alterations that occur in viral infections. |
|---|