In Vivo Targeted Vaccines for Tumor Immunotherapy

描述(由申请人提供)：由于树突状细胞(DC)在诱导T细胞介导的免疫方面具有突出的责任，因此在癌症的背景下，在体内针对DC的疫苗的靶向性是直观的。热休克蛋白70(HSP70)与树突状细胞表面抗原(Ag)摄取和信号受体结合，可作为树突状细胞靶向分子，提高疫苗免疫效果。淋巴组织中活化的含银树突状细胞的寿命也是与诱导特异性免疫密切相关的重要问题。延长体内载银DC的存活时间可能会增强DNA疫苗的效力。我们最近已经证明，DNA疫苗中编码的由肿瘤抗原和HSP70组成的融合蛋白(Aghsp70)可以诱导显著的抗肿瘤免疫。此外，通过传递“生存基因”bc l-xl延长DC的存活时间，从而增强了这些疫苗的效力。我们假设：1)体内靶向DC的Aghsp70刺激DC激活并诱导T细胞免疫；2)携带Aghsp70的DC存活时间的延长大大提高了抗原特异性T细胞应答的大小和质量，从而产生了潜在的临床益处。为了验证这一假说，我们将追求三个特定目标：特定目标1：测试OVAhsp70蛋白是否通过TLR4/CD40联合触发激活DC，并通过CD91/CD40/LOX-1受体介导的Ag摄取增强DC的抗原提呈能力，从而诱导强大的OVA特异性T细胞反应；特定目标2：测试DNA疫苗在体内能否通过延长OVAhsp70携带OVAhsp70的DC存活来诱导强大而持续的OVA特异性T细胞反应；特定目标3：评估体内靶向疫苗诱导的抗肿瘤免疫的有效性。这些研究的实验结果将有助于优化未来的肿瘤疫苗设计，并为DC免疫生物学提供更多的见解。

DESCRIPTION (provided by applicant): As dendritic cells (DCs) have pre-eminent responsibility for inducing T cell-mediated immunity, the targeting of vaccines to DCs in vivo is intuitively obvious in the setting of cancer. Heat shock protein hsp70 (hsp70) binds to both antigen (Ag)-uptake and signaling receptors on DCs and may serve as a DC targeting molecule capable of improving the efficacy of vaccines. The longevity of activated Ag-bearing DCs in lymphoid tissues is also an important issue germane to the induction of specific immunity. Prolonging Ag-bearing DC survival in vivo may potentiate the potency of DNA vaccines. We have recently demonstrated that fusion proteins composed of tumor Ag and hsp70 (Aghsp70) that are encoded in DNA vaccines induce significant anti-tumor immunity. Furthermore, the efficacy of these vaccines was augmented by prolonging DC survival via the delivery of the 'survival gene' Bcl-xl. We hypothesize that: 1) the in vivo targeting of Aghsp70 to DCs stimulates DC activation and induces T cell-mediated immunity and 2) that the prolongation of Aghsp70-bearing DC survival greatly improves the magnitude and quality of Ag-specific-T cell responses, resulting in potent clinical benefit. To test this hypothesis, we will pursue three specific aims: Specific Aim 1: Test whether OVAhsp70 proteins activate DCs via combined TLR4/CD40 triggering and enhance DC Ag-presenting capacity via CD91/CD40/LOX-1 receptor-mediated Ag-uptake, resulting in the induction of potent OVA-specific-T cell responses; Specific Aim 2: Test whether strong and sustained OVA-specific-T cell responses can be induced by the in vivo prolongation of OVAhsp70-bearing DC survival resulting from DNA vaccination; Specific Aim 3: Evaluate the efficacy of anti-tumor immunity induced by the In Vivo Targeted Vaccines. Experimental results obtained from these studies will be important in helping to optimize future tumor vaccine designs and provide additional insight into DC immunobiology.