Expression and functionality of toll-like receptor 3 in the megakaryocytic lineage

D'ATRI, P; ETULAIN, J; RIVADENEYRA, L; LAPPONI, M; FONDEVILA, C; SCHATTNER, M

Amsterdam

Congreso; XXIV Congress of the International Society on Thrombosis and Haemostasis (ISTH) 2013.; 2013

International Society of Thrombosis and Haemostasis

Background: Beyond having a key role in hemostasis, platelets and megakaryocytes also regulate the immune and inflammatory response, partially due to the expression of Toll-like receptors (TLRs) a family of proteins, which recognize molecular components of pathogens. Among the TLRs, TLR3 recognizes double-stranded (ds) RNA associated with viral infection, and induces the activation of the transcription nuclear factor-kB (NF-kB) and the production of type I interferons (IFN-I). We have previously demonstrated that Junin virus (JV), an arenavirus causative of Argentine hemorrhagic fever, or Poly(I:C), a synthetic dsRNA, ligand of TLR3, impair thrombopoiesis by decreasing release of in vitro generated-platelets. Moreover, JV or Poly(I:C) increase the expression of functional IFN-I receptor and induce the synthesis/release of IFN-I in early progenitors and mature megakaryocytes. Although we have shown TLR3 expression in megakaryocytes by RT-PCR, its expression and functionality in the megakaryocytic linage has not yet been studied. Aims: To study the expression and functionality of TLR3 in the megakaryocytic lineage. Methods: TLR3 expression was determined in human hematopoietic progenitors cells (CD34+), CD34+-derived megakaryocytes and peripheral blood platelets by RT-PCR, immunofluorescence and flow cytometry (FC). The TLR3 signaling pathways were evaluated by western blot. Platelet functionality was assayed by lumiaggregometry and FC. IFN-beta release was determined by ELISA.