Exopolysaccharide from Trichoderma pseudokoningii induces macrophage activation

In this study, we evaluated the immunomodulatory activity of an exopolysaccharide (EPS) derived from Trichoderma pseudokoningii and investigated the molecular mechanism of EPS-mediated activation of macrophages. Results revealed that EPS could significantly induce the production of nitric oxide (NO), tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta and enhance phagocytic activity in RAW 264.7 cells. Immunofluorescence staining indicated that EPS promoted the nuclear translocation of nuclear factor (NF)-kappa B p65 subunit. Western blot analysis showed that EPS increased the expression of inducible nitric oxide synthase (iNOS) protein, the degradation of I kappa B-alpha and the phosphorylation of mitogen-activated protein kinases (MAPKs). Furthermore, pretreatment of RAW 264.7 cells with specific inhibitors of NF-kappa B and MAPKs significantly attenuated EPS-induced TNF-alpha and IL-1 beta production. EPS also induced the inhibition of cytokine secretion by special antibodies against Toll-like receptor-4 (TLR4) and Dectin-1. These data suggest that EPS from Trichoderma pseudokoningii activates RAW 264.7 cells through NF-kappa B and MAPKs signaling pathways via TLR4 and Dectin-1. (C) 2016 Elsevier Ltd. All rights reserved.