Toll-like receptor control of endocytic antigen cross-presentation

建议书摘要 在诱导细胞毒性CD8T细胞对抗细胞内病原体方面，存在关键的疫苗障碍。当前 疫苗技术在预防细胞内病原体感染方面取得的成功有限 像结核病、疟疾和艾滋病毒，CD8 T细胞可以预防和控制感染。获得许可的疫苗产生 主要是中和或调理抗体，其疗效取决于稳定的抗原谱。一些人 明胶等佐剂可激发辅助性2型CD4T细胞，但CD8T细胞免疫一直难以实现。CD8 T细胞可以靶向保守的内部微生物成分，这些成分更难被病原体突变。这个 CD8 T细胞介导的无与伦比的效力、交叉保护免疫和免疫记忆 强调了开发CD8 T细胞疫苗的紧迫性。为了诱导CD8 T细胞免疫，佐剂需要 通过树突状细胞(DC)诱导MHC呈递疫苗配方中存在的抗原， 原始CD8 T细胞的抗原提呈细胞。MHC-I类外源抗原的呈递 因为DC的疫苗成分是通过交叉呈现发生的。了解以下机制 因此，调节DC交叉递呈对于设计能激发强大CD8 T细胞免疫的佐剂至关重要。我们的 已发表和未发表的研究表明，Toll样受体(TLR)可以检测微生物并提醒 免疫系统，正向调节DC的交叉提呈。在研究交叉呈现的规则时， 重要的是要考虑抗原内化进入DC的途径。取决于内部化的 抗原的内化可以通过吞噬作用(对于直径为1微米的颗粒)或内吞作用来实现 (&lt；直径1微米)。我们发现，依赖于TLR的交叉呈递调节对内细胞是不同的 和吞噬细胞抗原。决定CD8 T交叉演示效率的公共组件 细胞是正确的MHC-I分子向内化抗原部位的亚细胞运输。对于吞噬细胞抗原， TLR信号控制DC内小体循环室(ERC)中MHC-I分子的交通 特别是针对吞噬细胞抗原，例如来自细菌或受感染的垂死细胞。对于内吞抗原，我们发现 参与了一种独特的TLR信号机制，该机制控制内源性抗原与CD8的交叉提呈 T细胞并将MHC-I分子从ERC以外的细胞来源运送到内吞的抗原。使用 多种有效和互补的方法，我们将研究TLR调节内吞的机制 抗原交叉提呈和亚细胞MHC-I转运到内吞的抗原。我们将阐明 不同的TLR机制调节内细胞性抗原交叉递呈影响保护性循环和 疫苗诱导的组织驻留CD8 T细胞记忆。我们将使用研制的原型亚单位疫苗 使用佐剂/TLR配基组合，参与并促进DC内分泌抗原的交叉递呈。 破译细胞内抗原交叉递呈的调节机制将直接影响到内毒素的设计 有效的CD8T细胞疫苗用于临床相关的新旧病原体，包括那些具有大流行潜力的病原体。

PROPOSAL SUMMARY There are critical vaccine barriers to eliciting cytotoxic CD8 T cells against intracellular pathogens. Current vaccine technologies have yielded limited success for protection against infections with intracellular pathogens like tuberculosis, malaria, and HIV where CD8 T cells prevent and control infection. Licensed vaccines generate mostly neutralizing or opsonizing antibodies, and their efficacy is contingent on a stable antigenic profile. Some adjuvants like alum elicit helper type 2 CD4 T cells, but CD8 T cell immunity has been difficult to achieve. CD8 T cells can target conserved internal microbial components that are more difficult for pathogens to mutate. The unparalleled potency, cross-protective immunity, and immunological memory mediated by CD8 T cells underscores the urgency of developing CD8 T cell vaccines. To elicit CD8 T cell immunity, an adjuvant needs to induce MHC presentation of the antigens present in the vaccine formulation by dendritic cells (DC), potent antigen-presenting cells that prime naïve CD8 T cells. The MHC class I presentation of exogenous antigens such as vaccine components by DC takes place through cross-presentation. Understanding the mechanisms that regulate DC cross-presentation is thus critical for designing adjuvants that elicit strong CD8 T cell immunity. Our published and unpublished work has shown that Toll-like receptors (TLR), which detect microbes and alert the immune system, positively regulate DC cross-presentation. When studying the regulation of cross-presentation, it is important to consider the route of antigen internalization into DC. Depending on the size of the internalized antigen, internalization can be through phagocytosis (for particles that are >1µm in diameter) or endocytosis (<1µm in diameter). We found that the TLR-dependent regulation of cross-presentation is different for endocytic and phagocytic antigens. The common component that dictates the efficiency of cross-presentation to CD8 T cells is correct subcellular trafficking of MHC-I molecules to sites of internalized antigen. For phagocytic antigens, TLR signals control the traffic of MHC-I molecules from endosomal recycling compartments (ERC) in DC specifically to phagocytic antigens such as from bacteria or infected dying cells. For endocytic antigens, we found that a distinct TLR signaling machinery is involved, which controls endocytic antigen cross-presentation to CD8 T cells and traffics MHC-I molecules to endocytosed antigen from a cellular source other than the ERC. Using a variety of validated and complementary approaches, we will investigate TLR-regulated mechanisms of endocytic antigen cross-presentation and subcellular MHC-I trafficking to endocytosed antigens. We will elucidate how the distinct TLR mechanisms that regulate endocytic antigen cross-presentation impact protective circulating and tissue-resident CD8 T cell memory elicited by vaccination. We will use prototype subunit vaccines formulated with adjuvant/TLR ligand combinations that engage and boost DC endocytic antigen cross-presentation. Deciphering regulatory mechanisms of endocytic antigen cross-presentation will directly impact the design of effective CD8 T cell vaccines to clinically relevant old and new pathogens including those with pandemic potential.