Modulation of Mast Cell Toll-Like Receptor 3 Expression and Cytokines Release by Histamine.

BACKGROUND/AIMS: As a major inflammatory molecule released from mast cell activation, histamine has been reported to regulate TLRs expression and cytokine production in inflammatory cells present in the microenvironment. In this study, we determined the ability of histamine to modulate TLRs expression and cytokine production in mast cells.

METHODS: HMC-1 and P815 cells were exposed to various concentrations of histamine in the presence or absence of histamine antagonist for 2, 6 or 16 h. The effect of histamine on the expression of TLR3 protein and mRNA was analyzed by flow cytometry、 RT-PCR and immunofluorescent microscopy. Furthermore, we also examined the effect of histamine on the secretion of MCP-1 and IL-13 from mast cells by ELISA.

RESULTS: The amplification of TLR3 mRNA and protein expression in mast cells was observed after incubation with histamine, which was accompanied by increasing secretion of IL-13 and MCP-1 via H1 receptor. The signaling pathways of PI3K/ Akt and Erk1/2/MAPK contributed to these induction effects.

CONCLUSION: These results demonstrate that histamine up-regulates the expression of TLR3 and secretion of IL-13 and MCP-1 in mast cells, thus identifying a new mechanism for the histamine inducing allergic response.