Triptolide inhibits IL-12 production and T cell-stimulatory capacity of dendritic cells

Triptolide is a natural, biologically active component derived from Chinese herb Tripterygium Wilfordii Hook F. (TWHF) which is effective in the clinical treatment of autoimmune diseases, however, the mechanisms by which triptolide exerts immunosuppression remain fully understood. The primary of this study is to demonstrate whether triptolide can affect phenotype, cytokine production and allogeneic T cell-stimulatory capacity of dendritic cells (DCs) which are critical in the induction of immune response or tolerance. Phenotypic analysis show that triptolide does not affect the expression of MHC (Ia b), CD80, CD86 and CD40 of DC stimulated with or not LPS, but significantly inhibits IL-12p70 production by DC in a dose-dependent manner. Triptolide-treated DCs exhibit a reduced capacity to stimulate proliferation of allogeneic CD4 + T lymphocytes. Therefore, triptolide-mediated immunosuppression may due, in part, to the inhibition of IL-12p70 production and impairment of allogeneic T cell-stimulatory capacity of DCs. Our results may provide a possible mechanistic explanation for the effectiveness of triptolide in the treatment of autoimmune diseases.

Intratumoral Expression of MIP-1β Induces Antitumor Responses in a Pre-Established Tumor Model through Chemoattracting T Cells and NK Cells

Direct intratumoral introduction of therapeutic or regulatory genes is a developing technology with potential application for cancer gene therapy.Macrophage inflammatory protein-I beta(MIP-Iβ)is a chemokine which can chemoattract immune cells such as T cells.In the present study,murine colorectal adenocarcinoma CT26 cells were transfected with a recombinant adenovirus (AdhMIP-Iβ)carrying the human MIP-Iβ gene.24 h post-transfection,hMIP-1β levels reached approximately 980 pg/ml in supernatants of 10~6 hMIP-Iβ-transfected CT26 cells.Moreover,the supernatants exhibited chemotactic activity for CD8^+ T cells,CD4^+ T cells,NK cells and immature DCs.Intratumoral injection of AdhMIP-Iβ significantly inhibited tumor growth and prolonged the survival time of tumor-bearing mice.Intratumoral hMIP-Iβ gene transfer also induced powerful tumor-specific CTL responses in vivo.The therapeutic effects of hMIP-Iβ gene therapy were greatly reduced following in vivo depletion of both CD4^+ and CD8^+ cells,but were unaffected by depletion of single T cell subsets.Immune cell depletion experiments also revealed that NK cells played an important role in hMIP-1β-induced antitumor responses.These results suggest that intratumoral expression of hMIP-1β has the potential effect to induce host antitumor immunity and may prove to be a useful form of cancer gene therapy. Cellular & Molecular Immunology.2004;1(3):199-204.