The Role And Mechanism Of Dectin-1-mediated Syk/NF-?B Signaling Pathway In Talaromyces Marneffei Infection

Objectives:To explore the role and mechanism of Dectin-1-mediated Syk/NF-?B signaling pathway in Talaromyces Marneffei infection.Methods:PMA was used to induce THP-1 cells to differentiate into macrophages.A model in vitro of THP-1 macrophages infected by TM spores and hyphae is established,and PCR-Array was used to screen differential gene expressions in the THP-1 macrophages.RT-qPCR and Western Blot were used to detect the expression level of Dectin-1 on the surface of THP-1 macrophages.The phosphorylation levels of Syk,p65 and I?B? were detected by Western Blot,and the nuclear translocation of p65 protein in cytoplasm was observed by immunofluorescence.The secretion levels of TNF-? and IL-8 were detected by ELISA.THP-1 cells were infected by lentivirus-mediated siRNA,and a THP-1 cell model with low expression of Dectin-1 was established.Co-cultured with spores of TM,the phosphorylation levels of Syk,p65 and I?B?,as well as the nuclear translocation of p65 protein were analyzed by Western Blot and immunofluorescence,respectively.Additionally,the secretion levels of TNF-? and IL-8 were detected by ELISA.Results:THP-1 macrophages were stimulated by TM spores or hyphae,the mRNA and protein expression of Dectin-1 within 12 hours in the cells increased significantly with the prolongation of stimulation time.The phosphorylation levels of Syk,p65 and I?B? protein enhanced distinctly with the prolongation of stimulation time.However,the expression of I?B? protein decreased.Compared with control group,the fluorescence intensity of nuclear p65 in THP-1 macrophages was remarkably intensified.The expression levels of TNF-? and IL-8 inflammatory factors in cell culture supernatants increased significantly during 18h with the prolongation of stimulation time.After Dectin-1 expression was down-regulated,phosphorylation levels of Syk,p65 and I?B? were inhibited,as well as the nuclear translocation of p65 protein.Furthermore,the secretions of TNF-? and IL-8 inflammatory factors were also suppressed.Conclusions:Infected by TM,the expression of Dectin-1 on the surface of THP-1 macrophages was upregulated and NF-?B signaling pathway was activated to induce the release of TNF-? and IL-8.