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ABSTRACT: We have evaluated the capacity of a novel, nanoparticle-based tumor vaccine to eradicate established tumors in mice. C57BL/6 mice were intradermally (i.d.) inoculated with ovalbumin (OVA)-expressing EG-7 tumor cells. When the tumor size reached 7-8 mm, the tumor-bearing mice were i.d. injected near the tumor-draining lymph node (DLN) with liposomes encapsulated with unmethylated cytosine-phosphorothioate-guanine containing oligodeoxynucleotides (CpG-ODN) (CpG-liposomes) co-encapsulated with OVA. This vaccination protocol markedly prevented the growth of the established tumor mass and approximately 50% of tumor-bearing mice became completely cured. Tumor eradication correlated with the generation of OVA/H-2K(b)-tetramer(+) CTLs in the tumor DLN and at the tumor site with specific cytotoxicity toward EG-7 cells. Interestingly, tetramer(+) CTLs failed to be induced in lymph node-deficient Aly/Aly mice. Thus, tetramer(+) CTLs appeared to be generated in the tumor DLN and subsequently migrated into the tumor site. In vivo antibody blocking experiments revealed that CD8(+) T cells, but not CD4(+) T, NK or NKT cells, were the major effector cells mediating tumor eradication. CTL induction was also inhibited when vaccinated tumor-bearing mice were treated with both anti-IFN-alpha and anti-IFN-beta mAbs but not with anti-IFN-alpha or anti-IFN-beta mAb alone. Neither IFN-gamma(-/-) nor IL-12(-/-) mice showed impaired induction of tetramer(+) CTLs. Thus, these findings revealed that CpG-ODN-induced IFN-alpha/beta, but not IL-12 or IFN-gamma, is critical for the generation of tumor-specific CTLs in response to vaccination. These results highlight the potential utility of CpG-liposomes co-encapsulated with protein tumor antigens as therapeutic vaccines in cancer patients.
International Immunology 04/2006; 18(3):425-34. · 3.41 Impact Factor
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ABSTRACT: Various dendritic cell subsets are induced from bone marrow cells under different cytokine conditions. We have demonstrated previously that the Th1-cytokine-conditioned bone marrow-derived dendritic cell (BMDC) subset BMDC1 (generated in the presence of granulocyte-macrophage colony-stimulating factor [GM-CSF] + interleukin [IL]-3 + interferon [IFN]-gamma+ IL-12) induces a much stronger type 1 immune response than BMDC0 (GM-CSF + IL-3). In the present study, we investigated the effect of 1alpha,25-dihydroxyvitamine D3 (VitD3), which is a known immunomodulating drug, on the differentiation of BMDC subsets. The addition of VitD3 significantly influenced the functional differentiation of BMDC1 compared with BMDC0. Specifically, the addition of VitD3 greatly decreased the expression levels of MHC class I, CD80, CD40 and leukocyte function-associated antigen (LFA)-1 molecules on BMDC1. In addition, VitD3-treated BMDC1 (VD3-BMDC1) almost completely lost their immunostimulating activity for inducing type 1 immunity and cytotoxic T lymphocyte generation. A failure in the induction of type 1 immunity by VD3-BMDC1 appeared to be due to the following: (i) the expression of co-stimulatory molecules on VD3-BMDC1 was strongly downmodulated compared with BMDC1 generated without VitD3; and (ii) VD3-BMDC1 showed significantly lower mRNA expression of IFN-gamma and IFN-beta, factors that are essential for cytotoxic T lymphocyte induction. VitD3 inhibited the differentiation of functionally competent BMDC1 during the early phase of differentiation but not during the late differentiation period. A possible reason for the inhibition of BMDC1 differentiation by VitD3 is reduced phosphorylation of STAT1 during early differentiation. Taken together, VitD3 strongly suppressed T-cell responses by inhibiting functional differentiation of precursor dendritic cells into functional BMDC1 that are feasible for inducing Th1-dependent cellular immunity.
Cancer Science 03/2006; 97(2):139-47. · 3.33 Impact Factor
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ABSTRACT: Prior studies have shown that transfer of ovalbumin (OVA)-specific T helper type 1 (Th1) cells into mice bearing MHC class II+ OVA-expressing tumor cells (A20-OVA) causes complete tumor rejection. Here we show that, although Th1 cell therapy alone was not effective against MHC class II- OVA-expressing tumor cells (EG-7), treatment of mice bearing established EG-7 tumors by i.v. transfer of Th1 cells combined with i.t. injection of the model tumor antigen OVA induced complete tumor rejection. Transferred Th1 cells enhanced the migration of tumor-infiltrating antigen-presenting cells (APC) that had processed OVA into the draining lymph node (DLN). Although transferred Th1 cells were randomly distributed in DLN, distal LN, spleen, and tumor tissue, active proliferation of Th1 cells always initiated in DLN, where Th1 cells efficiently interacted with APC that presented OVA. In parallel, OVA-tetramer+ CTLs, showing EG-7-specific cytotoxicity, were highly induced in DLN and the local tumor site. The OVA-tetramer+ CTL functioned systemically because two bilateral tumor masses were both completely rejected on treatment of one tumor. Furthermore, either active proliferation of transferred Th1 cells or generation of tetramer+ CTL was not induced in MHC class II-deficient mice and LN-deficient Aly/Aly mice. These results indicate that DLN is an indispensable organ for initiating active APC/Th1 cell interactions, which is critical for inducing complete eradication of tumor mass by tumor-specific CTL.
Cancer Research 03/2006; 66(3):1809-17. · 7.86 Impact Factor
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ABSTRACT: The immune balance controlled by CD4(+) helper T cell subsets (T helper 1 (Th1) and T helper 2 (Th2)) is crucial for immunoregulation and its imbalance causes various immune diseases including infections, allergic disorders and autoimmune diseases. Therefore, it is of great importance to develop a system of diagnosing Th1/Th2 imbalances for curing immune diseases. Here we developed a functional cDNA array filter useful for assessing the Th1/Th2 balance in mice. To overcome the disadvantages of conventional microarrays carrying thousands of genes, we prepared an array filter containing 40 Th1-specific and 32 Th2-specific genes, which were selected from over 8700 genes based on (i) the specificity of expression in Th1 or Th2 cells and (ii) an expression level which is high enough for detection using a DNA array. This array filter provided a prompt and precise evaluation for the skewing of the Th1/Th2 balance combined with our calculation algorithm. The bias toward Th1 or Th2 was evaluated visually at a glance by aligning the genes on the filter. Moreover, we succeeded in evaluating the skewing of the Th1/Th2 balance in vivo during acute graft versus host disease (GVHD). Thus, this array filter will provide a novel tool for evaluation of the Th1/Th2 balance in a variety of immune diseases.
Immunology Letters 11/2005; 101(1):95-103. · 2.53 Impact Factor
