ABSTRACT
Objective To investigate the effects of mannan-binding lectin(MBL) on TNF-α production induced by peptidoglycan (PGN) and its mechanism in human THP-1/CD14 monocytes.Methods The THP-1/CD14 cells were stimulated for 24 h with PGN at the indicated ratios after pretreated with human natural MBL at concentrations ranging from 1 to 20 mg/L for 2 h.The content of TNF-α and IL-6 in culture supernatants were detected by ELISA,and the levels of TNF-α and IL-6 mRNA expressions in these cells were determined by RT-PCR.FACS was used to investigate the interaction of MBL with THP-1/CD14 cells and the impact of MBL on PGN binding to THP-1/CD14 cells.Western blot was used to detect PGN-induced NF-κB translocation in THP-1/CD14 cells.Results ELISA showed that secretion of TNF-α and IL-6 from THP-1/CD14 cells could be induced by PGN ;The productions of TNF-α and IL-6 by THP-1/CD14 cells induced with PGN were profoundly inhibited by MBL at higher concentrations (10-20 mg/L) but not MBL at lower concentrations (1 mg/L).RT-PCR analysis also indicated that the mRNA expressions of TNF-α and IL-6 in THP-1/CD14 cells were decreased by MBL at higher concentration,compared to the corresponding THP-1/CD14 cells stimulated with PGN only.FACS showed that the binding of MBL to THP-1/CD14 cells was evident in a Ca2+-dependent manner.PGN could competitively inhibit the binding of MBL to THP-1/CD14 cells.MBL could competitively inhibit the binding of PGN to THP-1/CD14 cells by binding to THP-1/CD14 cells directly.Similarly,MBL at higher concentration (20 mg/L) decreased the NF-κB translocation in THP-1/CD14 cells.Conclusion MBL may inhibit TNF-α and IL-6 production induced by PGN in THP-1/CD14 cells through NF-κB signaling pathways,suggesting that MBL can play some roles in the regulation of PGN-induced inflammatory response.
ABSTRACT
Objective To investigate the effects of mannan-binding lectin (MBL) on IL-8 and TNF-α production induced by Candida albicans ( C. albicans) in human THP1/CD14 monocytes. Methods The THP1/CD14 cells were stimulated for 24 h with heat-inactivated yeast form or hyphal form cells of C. albicans strain at the indicated ratios after pretreated with human natural MBL at concentrations ranging from 1 to 20 mg/L for 2 h. The content of IL-8 and TNF-α in culture supernatants were detected by ELISA,and the levels of IL-8 and TNF-α mRNA expressions in these cells were determined by RT-PCR. Western blot was used to detect C. albicans-induced NF-κB translocation in THP1/CDI4 cells. Results ELISA showed that secretion of IL-8 and TNF-α from THP1/CD14 cells could be induced by both yeast cells and hyphal cells. Hyphal cells proved to be much less efficient than yeast cells in stimulating production of IL-8and TNF-α by THP1/CD14 cells. The productions of IL-8 and TNF-α by THP1/CD14 cells induced with C.albicans were profoundly inhibited by MBL at higher concentrations ( 10-20 mg/L) but not MBL at lower concentrations ( 1 mg/L). RT-PCR analysis also indicated that the mRNA expressions of IL-8 and TNF-αt in THP1/CD14 cells were decreased to various extents by MBL at higher concentration, compared to the corresponding THP1/CD14 cells stimulated with C. albicans only. Similarly, MBL at higher concentration ( 20mg/L) decreased the NF-κB translocation in THP1/CD14 cells. Conclusion MBL may inhibit IL-8 and TNF-α production induced by dimorphism C. albicans in THP1/CD14 cells, suggesting that MBL can play some roles on the regulation of C. albicans immune response.