ABSTRACT
In this study, we showed the direct interaction between Mycobacterium avium subsp. paratuberculosis fibronectin attachment protein (FAP) and toll-like receptor4 (TLR4) via co-localization and binding by using confocal microscopy and co-immunoprecipitation assays. FAP triggered the expression of pro- and anti-inflammatory cytokines in a TLR4-dependent manner. In addition, FAP-induced cytokine expression in bone marrow-derived dendritic cells (BMDCs) was modulated in part by glycogen synthase kinase-3 (GSK-3). FAP-induced expression of CD80, CD86, major histocompatibility complex (MHC) class I, and MHC class II in TLR4+/+ BMDCs was not observed in TLR4-/- BMDCs. Furthermore, FAP induced DC-mediated CD8+ T cell proliferation and cytotoxic T lymphocyte (CTL) activity, and suppressed tumor growth with DC-based tumor vaccination in EG7 thymoma murine model. Taken together, these results indicate that the TLR4 agonist, FAP, a potential immunoadjuvant for DC-based cancer vaccination, improves the DC-based immune response via the TLR4 signaling pathway.
Subject(s)
Animals , Humans , Mice , Adhesins, Bacterial/genetics , CD8-Positive T-Lymphocytes/metabolism , Cancer Vaccines/therapeutic use , Cell Proliferation , Cytokines/metabolism , Dendritic Cells/cytology , Disease Models, Animal , Gene Expression Regulation , Glycogen Synthase Kinase 3/metabolism , Mice, Inbred C57BL , Mycobacterium avium/genetics , Paratuberculosis/metabolism , Protein Binding , Signal Transduction , T-Lymphocytes, Cytotoxic/metabolism , Thymoma/genetics , Toll-Like Receptor 4/agonistsABSTRACT
BACKGROUND: Dendritic cell (DC)-based vaccines are currently being evaluated as a novel strategy for tumor vaccination and immunotherapy. However, inducing long-term regression in established tumor-implanted mice is difficult. Here, we show that deoxypohophyllotoxin (DPT) induces maturation and activation of bone marrow-derived DCs via Toll-like receptor (TLR) 4 activation of MAPK and NF-kappaB. METHODS: The phenotypic and functional maturation of DPT-treated DCs was assessed by flow cytometric analysis and cytokine production, respectively. DPT-treated DCs was also used for mixed leukocyte reaction to evaluate T cell-priming capacity and for tumor regression against melanoma. RESULTS: DPT promoted the activation of CD8+ T cells and the Th1 immune response by inducing IL-12 production in DCs. In a B16F10 melanoma-implanted mouse model, we demonstrated that DPT-treated DCs (DPT-DCs) enhance immune priming and regression of an established tumor in vivo. Furthermore, migration of DPT-DCs to the draining lymph nodes was induced via CCR7 upregulation. Mice that received DPT-DCs displayed enhanced antitumor therapeutic efficacy, which was associated with increased IFN-gamma production and induction of cytotoxic T lymphocyte activity. CONCLUSION: These findings strongly suggest that the adjuvant effect of DPT in DC vaccination is associated with the polarization of T effector cells toward a Th1 phenotype and provides a potential therapeutic antitumor immunity.