Dendritic cells (DCs) are armed with a multitude of Pattern Recognition Receptors (PRRs) to recognize pathogens and initiate pathogen-tailored T cell responses. In these responses, the maturation of DCs is key, as well as the production of cytokines that help to accomplish T cell responses. DC-SIGN is a frequently exploited PRR that can effectively be targeted with mannosylated antigens to enhance the induction of antigen-specific T cells. The natural O-mannosidic linkage is susceptible to enzymatic degradation, and its chemical sensitivity complicates the synthesis of mannosylated antigens. For this reason, (oligo)mannosides are generally introduced in a late stage of the antigen synthesis, requiring orthogonal conjugation handles for their attachment. To increase the stability of the mannosides and streamline the synthesis of mannosylated peptide antigens, we here describe the development of an acid-stable C-mannosyl lysine, which allows for the inline introduction of mannosides during solid-phase peptide synthesis (SPPS). The developed amino acid has been successfully used for the assembly of both small ligands and peptide antigen conjugates comprising an epitope of the gp100 melanoma-associated antigen and a TLR7 agonist for DC activation. The ligands showed similar internalization capacities and binding affinities as the O-mannosyl analogs. Moreover, the antigen conjugates were capable of inducing maturation, stimulating the secretion of pro-inflammatory cytokines, and providing enhanced gp100 presentation to CD8+ and CD4+ T cells, similar to their O-mannosyl counterparts. Our results demonstrate that the C-mannose lysine is a valuable building block for the generation of anticancer peptide-conjugate vaccine modalities.

中文翻译：

---

用于甘露糖基化肽的固相组装的C-甘露糖基赖氨酸偶联癌症疫苗。

树突状细胞（DC）配备了多种模式识别受体（PRR），以识别病原体并启动针对病原体的T细胞应答。在这些反应中，DC的成熟以及有助于完成T细胞反应的细胞因子的产生是关键。DC-SIGN是一种经常使用的PRR，可将其以甘露糖基化抗原有效地靶向，以增强对抗原特异性T细胞的诱导。天然的O-甘露糖苷键易被酶降解，其化学敏感性使甘露糖基化抗原的合成变得复杂。由于这个原因，（寡）甘露糖苷通常在抗原合成的后期被引入，其需要正交的缀合柄。为了增加甘露糖苷的稳定性并简化甘露糖基化肽抗原的合成，我们在此描述了酸稳定的C-甘露糖基赖氨酸的发展，该过程允许在固相肽合成（SPPS）期间在线引入甘露糖苷。所开发的氨基酸已成功用于组装小配体和肽抗原结合物，后者包括与gp100黑色素瘤相关的抗原的表位和用于DC活化的TLR7激动剂。所述配体显示出与O-甘露糖基类似物相似的内化能力和结合亲和力。此外，抗原缀合物能够诱导成熟，刺激促炎性细胞因子的分泌，并向CD8 +和CD4 + T细胞提供增强的gp100呈递，类似于其O-甘露糖基对应物。