Enhancing Immunological Memory Using Aptamertargeted siRNA Delivery to T Cells

描述（由申请人提供）：最近在小鼠、非人类灵长类动物和人类患者的临床试验中进行的研究强调了疫苗诱导的免疫反应、免疫记忆在介导对传染病和癌症的保护性免疫中的持久性的重要性。值得注意的是，通过遗传手段或任何可用的药理学手段抑制mTOR、GSK3b、Blimp-1或T-bet等效应物分化的介质，不仅可以阻止短期效应物的积累，还可以重新定向激活的T细胞沿记忆途径分化，增强疫苗诱导的小鼠保护性免疫。尽管如此，用于抑制mTOR的药物，如雷帕霉素，往往表现出不良的免疫抑制作用，反映了其靶点的广泛分布。在这里，我们建议开发一个通用的，广泛的

DESCRIPTION (provided by applicant): Recent studies in mice, nonhuman primates, and clinical trials in human patients have emphasized the importance of the persistence of the vaccine-induced immune response, immunological memory, in mediating protective immunity against infectious diseases and cancer. Notably, inhibition of mediators of effector differentiatio like mTOR, GSK3b, Blimp-1 or T-bet, using genetic means or whenever available pharmacological agents, not only prevented the accumulation of the short-lived effectors but also redirected the activated T cells to differentiate along the memory pathway, and potentiated vaccine-induced protective immunity in mice. Notwithstanding, pharmacological agents, like rapamycin that was used to inhibit mTOR, often exhibit undesirable immune suppressive effects reflecting the broad distribution of their targets. Here we propose to develop a versatile, broadly applicable, and clinically feasible approach to promote the generation of memory T cell responses that addresses the main limitations of pharmacological agents. We propose to use RNAi to downregulate intracellular mediators of effector differentiation that will be targeted to CD8+ T cells by conjugation to oligonucleotide aptamer ligands. Aptamer and aptamer-siRNA conjugates offer potentially important advantages in terms of synthesis, conjugation, and reduced immunogenicity. The central hypothesis of the proposed studies is that aptamer-targeted siRNA inhibition of intracellular mediators in vaccine-induced CD8+ T cells will enhance their differentiation into long-lasting memory T cells and potentiate antitumor immunity that will be superior to pharmacological agents in terms of reduced toxicity, increased efficacy, and applicability to "nondrugable" intracellular targets. The proposed approach is supported by preliminary studies showing that 4-1BB aptamer-targeted raptor siRNA inhibition of mTORC1 function in activated CD8+ T cells led to the generation of a potent memory response and enhanced vaccine-induced protective immunity in tumor-bearing mice that was superior to that of rapamycin. The specific goal of the studies proposed in this application is to identify a best-i-class aptamer-siRNA conjugate to potentiate vaccine-induced protective immunity as determined in murine tumor models (Aims #1 and #2), that will guide the development of human conjugates capable of promoting the persistence of antigen- activated T cells in vitro (Aim #3). Successful accomplishment of the goals of the proposed studies will set the stage for clinical trials to potentiate vaccine-induced protective immunity in cancer patients using the agents developed in this proposal. Promoting memory differentiation by inhibition of intracellular mediators using siRNAs that are targeted to activated CD8+ T cells by conjugation to oligonucleotide aptamer ligands is arguably novel. The ability to target siRNAs to specific subsets of circulating immune or hematopoietic cells will provide a novel tool to manipulate the immune and hematopoietic systems for both investigational and therapeutic purposes.