Cryptomerione induces Th1 cell polarization via influencing IL-10 production by cholera toxin-primed dendritic cells

Dendritic cells play an important role in the initiation and regulation of immune response. Dendritic cells have a key influence in the differentiation of naïve T cells into Th1, Th2 or Th17 effector cells. Cryptomerione is terpene isolated from the heartwood of Cryptomeria japonica. In this study, we investigated the effects of Cryptomerione on the phenotypic and functional maturation of human monocyte-derived dendritic cells in vitro. Human monocytes were exposed to either Cryptomerione alone, or in combination with lipopolysaccaride (LPS) or cholera toxin (CT) and thereafter co-cultured with naïve T cells. We found no enhanced CD1a, CD80, CD83, CD86 and HLA-DR expression on Cryptomerione-primed dendritic cells. However, Cryptomerione augmented T cell stimulatory capacity in an allogeneic mixed lymphocyte reaction to CT-primed dendritic cells and influenced the production of interleukin (IL)-10 and IL-12p70 by CT-primed dendritic cells, but not LPS-primed dendritic cells. Cryptomerione also inhibited Th2 cell polarization induced by CT-primed dendritic cells, but enhanced IFN-gamma secretion by naïve T cells co-cultured with CT-primed dendritic cells. Cytokine production by CT-primed dendritic cells alone, or in combination with Cryptomerione was also influenced following treatment with anti-IL-10 mAb and anti-OX40L mAb. Thus, the potential mechanisms underlying the enhancement of Th1 polarization in CT-primed dendritic cells induced by Cryptomerione appeared to depend on IL-10 secretion and OX40L. These results suggest that Cryptomerione modulates human dendritic cells function in a fashion that favors Th1/Th2 cell polarization.