Short peptides are the minimal modality of antigen recognized by cellular immunity and are therefore considered a safe and highly specific source of antigen for vaccination. Nevertheless, successful peptide immunotherapy is limited by the short half-life of peptide antigens in vivo as well as their weak immunogenicity. We recently reported a vaccine strategy based on dendritic cell-recruiting Mesoporous Silica Rod (MSR) scaffolds to enhance T-cell responses against subunit antigen. In this study, we investigated the effect of covalently conjugating peptide antigens to MSRs to increase their retention in the scaffolds. Using both stable thioether and reducible disulfide linkages, peptide conjugation greatly increased peptide loading compared to passive adsorption. In vitro, Bone Marrow derived Dendritic Cells (BMDCs) could present Ovalbumin (OVA)-derived peptides conjugated to MSRs and induce antigen-specific T-cell proliferation. Stable conjugation decreased presentation in vitro while reducible conjugation maintained levels of presentation as high as soluble peptide. Compared to soluble peptide, in vitro, expansion of OT-II T-cells was not affected by adsorption or stable conjugation to MSRs but was enhanced with reversible conjugation to MSRs. Both conjugation schemes increased peptide residence time in MSR scaffolds in vivo compared to standard bolus injections or a simple adsorption method. When MSR scaffolds loaded with GM-CSF and CpG-ODN were injected subcutaneously, recruited dendritic cells could present antigen in situ with the stable conjugation increasing presentation capacity. Overall, this simple conjugation approach could serve as a versatile platform to efficiently incorporate peptide antigens in MSR vaccines and potentiate cellular responses.

中文翻译：

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肽抗原与中孔硅胶棒的共价缀合以增强细胞反应

短肽是被细胞免疫识别的抗原的最小形式，因此被认为是用于疫苗接种的安全且高度特异性的抗原来源。然而，成功的肽免疫疗法受到体内肽抗原半衰期短以及免疫原性弱的限制。我们最近报告了基于树突状细胞招募中孔硅胶棒（MSR）支架，以增强针对亚基抗原的T细胞反应的疫苗策略。在这项研究中，我们调查了共价结合肽抗原与MSR的作用，以增加其在支架中的保留。同时使用稳定的硫醚键和可还原的二硫键，与被动吸附相比，肽的缀合大大增加了肽的负载量。体外，骨髓来源的树突状细胞（BMDCs）可能会呈现出卵白蛋白（OVA）衍生的肽与MSRs结合并诱导抗原特异性T细胞增殖。稳定的偶联减少了体外呈递，而可还原的偶联维持了与可溶性肽一样高的呈递水平。与可溶性肽相比，在体外， OT-II T细胞的扩增不受MSR吸附或稳定结合的影响，但可逆结合MSR的作用增强。与标准推注或简单的吸附方法相比，两种缀合方案均增加了其在体内MSR支架中的肽停留时间。皮下注射载有GM-CSF和CpG-ODN的MSR支架时，募集的树突状细胞可呈递抗原原位稳定的结合增加了表达能力。总体而言，这种简单的偶联方法可作为通用平台，将肽抗原有效地掺入MSR疫苗中并增强细胞应答。