TLR2 and TLR4 co-activation utilizes distinct signaling pathways for the production of Th1/Th2/Th17 cytokines in neonatal immune cells

摘要

Co-activation of TLR2 and TLR4 by gram negative and gram positive bacterial ligands induces a robust pro-inflammatory response in inflammatory cells. In order to understand the signaling mechanism, we aimed to delineate the signaling molecules involved in TLR2 and TLR4 co-activation in neonatal immune cells for the production of Th1/Th2/Th17 inflammatory cytokines. For this, we pretreated cord blood and peripheral blood mononuclear and human mast cells with specific signaling molecule inhibitors such as BAY117082, PD98059 and LY294002 and then stimulated with LPS and PGN and assayed for cytokines IL-6, IL-12/IL-23p40 (Th1), IL-13 (Th2), IL-23 (Th17) and RANTES secretion. We found that upon co-stimulation the phosphorylation of NF kappa Bp65, ERK1/2 and Akt was found to be higher than when stimulated with individual ligands in CBMCs. Also, when compared to adult cells, neonatal cells were more potent in the activation of ERIC and Akt through TLR2 and TLR4 co-activation. In addition, neonatal cells possess similar capacity to activate NF kappa B as that of adult cells for IL-6 secretion. Furthermore, all three signaling molecules were found to be involved in the production of Th17 cytolcines which is detrimental during inflammation induced by infection in neonates whereas NF kappa B is mainly involved in the induction of pro-inflammatory response and Th2 cytokines production. In conclusion, different signaling molecules were utilized for the production of different cytokines in immune cells. (C) 2016 Elsevier Ltd. All rights reserved.