Activation of Toll-like receptors 2 and 4 on CD 34 + cells increases human megakaryo/thrombopoiesis induced by thrombopoietin

POZNER, ROBERTO GABRIEL; CARRERA SILVA, EUGENIO ANTONIO; D'ATRI, LINA PAOLA; RODRÍGUEZ, CAMILA SOFÍA; ORTIZ WILCZYÑSKI, JUAN MANUEL; HELLER, PAULA; MIGUEL, CAROLINA PAULA; NEGROTTO, SOLEDAD; SCHATTNER, MIRTA

Congreso; Reunión Anual de la sociedad argentina de investigación clínica; 2019

Background: Platelet (PLT) toll like receptors (TLR) 2 and 4 are key players in amplifying the host immune response. However, its role in human megakaryo/thrombopoiesis has not yet been defined. Objectives: We evaluated whether Pam3CSK4 (Pam) or lipopolysaccharide (LPS), TLR2/4 ligands respectively, modulate human megakaryocyte (MK) development and PLT production. Methods: CD34+ cells from human umbilical cord were stimulated with LPS or Pam3CSK4 with or without thrombopoietin (TPO). TLRs expression was determined by RT-PCR and flow cytometry (FC). Differentiation, maturation, PLT generation, c-MPL (TPO receptor) expression and IL-6 production was evaluated by FC and proPLTs and NF-E2 migration by confocal microscopy. Results: CD34+ cells and MK express TLR2 and TLR4 at both RNA and protein level. Direct stimulation of CD34+ cells with LPS or Pam had no effect in cell growth. Interestingly, both TLR ligands markedly increased TPO-induced CD34+ cell proliferation, MK number and maturity, proPLT and PLT production when added at day 0 (n=7, p