A Mite Antigen, Der P1, Activates Dendritic Cells (DCs) and Stimulates Th2 Polarization through a Toll-like Receptor (TLR)-4 Pathway

Abstract

RationaleExposure to mite is implicated in the development and exacerbation of asthma and other allergic diseases. Therefore, we investigated whether a mite allergen, Der p 1, directly stimulates DCs and promotes allergic responses.MethodsWe cultured mouse bone marrow-derived DCs with Dermatophagoides pteronyssinus (DP) extract or purified natural Der p 1. Cell surface expression of co-stimulatory molecules and cytokine production were analyzed by FACS and by ELISA, respectively. Der p 1-stimulated DCs were also co-cultured with allogeneic CD4+ T cells, and T cell production of cytokines was analyzed.ResultsBoth DP extract and purified Der p 1 activated DCs, as shown by increased expression of co-stimulatory molecules (CD40, CD80, and CD86) and by IL-6 production. Heat treatment of Der p 1 abolished DC expression of co-stimulatory molecules and IL-6 production; proteinase K treatment of Der p 1 abolished IL-6 production. These treatments did not affect the ability of lipopolysaccharide (LPS) to stimulate DCs. When stimulated with Der p1 or LPS, DCs from TLR4-deficient mice produced less IL-6 compared to DCs from wild-type mice. Der p 1 treatment also downregulated TLR 4 expression in DCs from wild-type mice. When allogenic CD4+ T cells were incubated with Der p 1-treated DCs, the T cells showed enhanced production of IL-4, IL-5, and IL-13 and reduced production of IFN-γ. Heat treatment of Der p 1 abolished this Th2-driving effect.ConclusionDer p 1 activates DCs and facilitates CD4+ T cell production of Th2 cytokines through a TLR4-dependent mechanism. This effect is likely mediated by Der p 1 protein itself and not by LPS contamination. RationaleExposure to mite is implicated in the development and exacerbation of asthma and other allergic diseases. Therefore, we investigated whether a mite allergen, Der p 1, directly stimulates DCs and promotes allergic responses. Exposure to mite is implicated in the development and exacerbation of asthma and other allergic diseases. Therefore, we investigated whether a mite allergen, Der p 1, directly stimulates DCs and promotes allergic responses. MethodsWe cultured mouse bone marrow-derived DCs with Dermatophagoides pteronyssinus (DP) extract or purified natural Der p 1. Cell surface expression of co-stimulatory molecules and cytokine production were analyzed by FACS and by ELISA, respectively. Der p 1-stimulated DCs were also co-cultured with allogeneic CD4+ T cells, and T cell production of cytokines was analyzed. We cultured mouse bone marrow-derived DCs with Dermatophagoides pteronyssinus (DP) extract or purified natural Der p 1. Cell surface expression of co-stimulatory molecules and cytokine production were analyzed by FACS and by ELISA, respectively. Der p 1-stimulated DCs were also co-cultured with allogeneic CD4+ T cells, and T cell production of cytokines was analyzed. ResultsBoth DP extract and purified Der p 1 activated DCs, as shown by increased expression of co-stimulatory molecules (CD40, CD80, and CD86) and by IL-6 production. Heat treatment of Der p 1 abolished DC expression of co-stimulatory molecules and IL-6 production; proteinase K treatment of Der p 1 abolished IL-6 production. These treatments did not affect the ability of lipopolysaccharide (LPS) to stimulate DCs. When stimulated with Der p1 or LPS, DCs from TLR4-deficient mice produced less IL-6 compared to DCs from wild-type mice. Der p 1 treatment also downregulated TLR 4 expression in DCs from wild-type mice. When allogenic CD4+ T cells were incubated with Der p 1-treated DCs, the T cells showed enhanced production of IL-4, IL-5, and IL-13 and reduced production of IFN-γ. Heat treatment of Der p 1 abolished this Th2-driving effect. Both DP extract and purified Der p 1 activated DCs, as shown by increased expression of co-stimulatory molecules (CD40, CD80, and CD86) and by IL-6 production. Heat treatment of Der p 1 abolished DC expression of co-stimulatory molecules and IL-6 production; proteinase K treatment of Der p 1 abolished IL-6 production. These treatments did not affect the ability of lipopolysaccharide (LPS) to stimulate DCs. When stimulated with Der p1 or LPS, DCs from TLR4-deficient mice produced less IL-6 compared to DCs from wild-type mice. Der p 1 treatment also downregulated TLR 4 expression in DCs from wild-type mice. When allogenic CD4+ T cells were incubated with Der p 1-treated DCs, the T cells showed enhanced production of IL-4, IL-5, and IL-13 and reduced production of IFN-γ. Heat treatment of Der p 1 abolished this Th2-driving effect. ConclusionDer p 1 activates DCs and facilitates CD4+ T cell production of Th2 cytokines through a TLR4-dependent mechanism. This effect is likely mediated by Der p 1 protein itself and not by LPS contamination. Der p 1 activates DCs and facilitates CD4+ T cell production of Th2 cytokines through a TLR4-dependent mechanism. This effect is likely mediated by Der p 1 protein itself and not by LPS contamination.