Lam Jennifer S, Mansour Michael K, Specht Charles A, Levitz Stuart M
Department of Microbiology and Immunology Training Program, Boston University School of Medicine, MA 02118, USA.
J Immunol. 2005 Dec 1;175(11):7496-503. doi: 10.4049/jimmunol.175.11.7496.
Ag mannosylation represents a promising strategy to augment vaccine immunogenicity by targeting Ag to mannose receptors (MRs) on dendritic cells. Because fungi naturally mannosylate proteins, we hypothesized that Ags engineered in fungi would have an enhanced capacity to stimulate T cell responses. Using the model Ag OVA, we generated proteins that differentially expressed N- and O-linked mannosylation in the yeast Pichia pastoris and compared them to their unglycosylated counterparts produced in Escherichia coli. We found that yeast-derived OVA proteins containing N-linkages, extensive O-linkages, or both were more potent than the unmannosylated Ags at inducing OVA-specific CD4+ T cell proliferation. This elevated response to fungal Ags was inhibited by mannan, suggesting involvement of MRs. However, the macrophage MR (CD206) was not essential, because macrophage MR-deficient dendritic cells were fully competent in presenting yeast-derived OVA Ags. Thus, the use of fungal glycosylation to provide N-linked and/or extensive O-linked mannosylation increased the capacity of the model Ag OVA to stimulate Ag-specific T cell responses in an MR-dependent manner. These data have implications for vaccine design by providing proof of principle that yeast-derived mannosylation can enhance immunogenicity.
抗原甘露糖基化是一种很有前景的策略，可通过将抗原靶向树突状细胞上的甘露糖受体（MRs）来增强疫苗的免疫原性。由于真菌天然会将蛋白质甘露糖基化，我们推测在真菌中工程改造的抗原将具有更强的刺激T细胞反应的能力。使用模型抗原OVA，我们在酵母毕赤酵母中生成了差异表达N-和O-连接甘露糖基化的蛋白质，并将它们与其在大肠杆菌中产生的未糖基化对应物进行比较。我们发现，含有N-连接、广泛O-连接或两者皆有的酵母衍生OVA蛋白在诱导OVA特异性CD4+T细胞增殖方面比未糖基化的抗原更有效。对真菌抗原的这种增强反应被甘露聚糖抑制，表明MRs参与其中。然而，巨噬细胞MR（CD206）并非必不可少，因为巨噬细胞MR缺陷的树突状细胞在呈递酵母衍生的OVA抗原方面完全有能力。因此，利用真菌糖基化提供N-连接和/或广泛的O-连接甘露糖基化以MR依赖的方式增加了模型抗原OVA刺激抗原特异性T细胞反应的能力。这些数据为疫苗设计提供了原理证明，即酵母衍生的甘露糖基化可增强免疫原性，对疫苗设计具有重要意义。
