A C-Linked Disaccharide Analogue of Thomsen-Friedenreich Epitope Induces a Strong Immune Response in Mice
A C-Linked Disaccharide Analogue of Thomsen-Friedenreich Epitope Induces a Strong Immune Response in Mice
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DOI：
10.1002/chem.201200364
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发表时间：
2012-07-09
影响因子：
4.3
通讯作者：
Vogel, Pierre
中科院分区：
文献类型：
--
作者：
Awad, Loay;Madani, Rime;Vogel, Pierre
癌细胞可以表达异常的细胞表面糖基化模式，使其被免疫系统识别这种表型为开发以碳水化合物为基础的癌症免疫治疗疫苗提供了机会Thomsen-Friedenreich （TF）抗原是一种双糖（β-d-Galp-1-3-α-d-GalNAcp）癌胎血型相关抗原，通常与上皮组织分泌边界细胞上表达的粘液丝氨酸或苏氨酸（MUC） o连接。这种双糖与恶性肿瘤有关，并在乳腺癌和前列腺癌细胞与内皮细胞的对接过程中发挥重要作用用人工合成的TF-Keyhole帽贝血青素KLH结合疫苗，加上各种佐剂免疫，可产生高滴度的IgM和IgG抗体Danishefsky及其同事在高风险前列腺癌患者的多价ii期疫苗试验中发现，由二糖三肽簇偶联KLH构建的抗原1（+佐剂QS-21）是一个相关抗原靶点由于tnf表位β-d-Galp-1-3-α-d- galnap - ol -丝氨酸的双糖部分在体内被β-半乳糖苷酶水解，因此[6]需要比1更稳定的抗原。在与报道1相似的条件下，我们现在发现以QS21作为佐剂[7]的c -二糖类似物2在两次刺激后诱导小鼠产生强烈的免疫反应。这表明c -双糖可用于构建针对癌症和其他疾病的治疗性疫苗。当使用由α-d-Galp-1ACHTUNGTRENNUNG (CH2)-3-α-d- galnap - o -丝氨酸(α- c -半乳糖苷，而不是β- c -半乳糖苷构建的抗原3时，观察到免疫反应弱得多（见2；图1）。已经探索了将非天然抗水解碳水化合物类似物纳入疫苗结构的各种策略，包括使用c -糖苷[8]和s-糖苷[8b， 9] - o -糖苷类似物，以及o -脱氧氟糖苷b[10]也有人提出用β3-同型苏氨酸偶联物代替苏氨酸或丝氨酸来构建粘蛋白样糖肽抗原类似物在这篇报道中，我们探讨了在c -连接的双糖类似物中替换o -连接的双糖片段是否仍然会诱导免疫反应，以及后者是否取决于人工抗原的d-半乳糖苷片段的β-或α-构型。一个缩醛氧原子交换一个CH2基团（从缩醛变为醚功能）改变了双糖的极性和水溶性，也改变了它的两个糖苷间键的构象的分布。一些研究表明，c -键双糖的能量图与相应的o -键双糖的能量图相似，但在最小值[12]的位置和相对自由能上存在差异例如，β-d-Galp-(1ACHTUNGTRENNUNG (CH2)-4)-β-d- glcnacp - ome， c -d- glcnacp - ome在水溶液中具有三个不同的构象家族，其中主要的是反y构象，而o -键双糖只有少量的构象抗原2和抗原3的构建分别在方案1和方案2中概述，并在支持信息中详细描述。以醛4. bb0为起始原料，合成了tf -双糖的c -双糖模拟物伊藤-野崎缩合[15](4)
Cancer cells can express aberrant cell-surface-glycosylation patterns that makes them to be recognizable by the immune system.[1] This phenotype gives an opportunity to develop carbohydrate-based vaccines for cancer immunotherapy.[2] Thomsen–Friedenreich (TF) antigen is a disaccharide (β-d-Galp-1-3-α-d-GalNAcp) oncofetal blood group-related antigen normally O-linked to serines or threonines of mucines (MUC) expressed on cells at the secretory borders of epithelial tissues. The disaccharide is linked to malignancy and plays an important role in docking breast-and prostate-cancer cells onto endothelium.[3] Patients immunized with synthetic TF-Keyhole limpet hemocyanin KLH conjugate vaccines, plus various adjuvants can generate high-titer IgM and IgG antibodies.[4] Antigen 1 constructed from a disaccharide tripeptide cluster conjugated to KLH (+ adjuvant QS-21) has been shown by Danishefsky and co-workers to be a relevant antigen target in a multivalent phase II-vaccine trial in patients with high-risk minimal prostate cancer.[5] Because the disaccharide moiety of TF-epitope β-d-Galp-1-3-α-d-GalNAcp-Ol-serine is hydrolyzed by β-galactosidases in the body,[6] there is a need for more stable antigens than 1. Under similar conditions as reported for 1, we have now found that the C-disaccharide analogue 2 with QS21 as adjuvant [7] induces a strong immune response in mice after two boosts. This suggests that C-disaccharides can be used to construct therapeutic vaccines against cancer and other diseases. Much weaker immune response was observed when using antigen 3 constructed from α-d-Galp-1ACHTUNGTRENNUNG (CH2)-3-α-d-GalNAcp-O-serine (a α-C-galactoside rather than β-C-galactoside as in 2; Figure 1).Various strategies towards the incorporation of non-natural hydrolysis-resistant carbohydrate analogues into vaccine constructs have been explored, including the use of C-glycosides [8] and S-glycosides [8b, 9] analogues of O-glycosides, as well as O-deoxyfluoroglycosides.[10] It has been proposed also to use β3-homothreonine conjugates instead of threonine or serine to construct mucin-like glycopeptides antigen analogues.[11] In this report, we have explored whether the replacement of the O-linked disaccharide moiety in a C-linked disaccharide analogue would still induce an immune response, and whether the latter would depend on the β-or α-configuration of the d-galalactopyranoside moiety of the artificial antigen. The exchange of one acetal oxygen atom for a CH2 group (change from acetal to ether function) modifies the polarity and water solubility of the disaccharide, as well as the population of its conformers about the two interglycosidic bonds. Several studies have suggested that the energy maps of C-linked disaccharides are similar to maps of the corresponding O-disaccharides, but there are differences in the locations and the relative free energies of the minima.[12] For example, with β-d-Galp-(1ACHTUNGTRENNUNG (CH2)-4)-β-d-GlcNAcp-OMe, the C-disaccharide populates three distinctive conformational families in water solution, the major one being the anti-Y-conformation, which is only marginally populated for the O-linked disaccharide.[13] The construction of antigens 2 and 3 are outlined in Schemes 1 and 2, respectively, and are described in details in the Supporting Information. The synthesis of the C-disaccharide mimetic of the TF-disaccharide started with aldehyde 4.[14] Itoh–Nozaki condensation [15] of 4 with isolevoglu-