Evaluation of different α-galactosyl glycoconjugates for use in xenotransplantation
Evaluation of different α-galactosyl glycoconjugates for use in xenotransplantation
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DOI：
10.1021/bc015565e
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发表时间：
2002-05-01
影响因子：
4.7
通讯作者：
Logan, JS
中科院分区：
文献类型：
--
作者：
Byrne, GW;Schwarz, A;Logan, JS
猪器官在移植到灵长类动物受体中后会迅速排斥，这是由于存在与猪糖蛋白和糖脂上存在的末端半乳糖α 1，3半乳糖残基（α-半乳糖基）结合的预先存在的免疫球蛋白。目前可用的免疫抑制剂在控制这些抗Gal抗体的合成方面基本上无效。非抗原性半抗原聚合物已被证明是在各种模型系统中阻断体液免疫应答的有效材料。我们已经开发了一系列α-半乳糖基糖缀合物聚合物，并测试了它们在体外和体内阻断抗Gal抗体结合的能力。制备了具有己酸间隔基的半乳糖α 1，3半乳糖β 1，4 GlcNAc三糖游离酸（TRFA），其含有5个亚甲基和一个羧酸，并与多种聚合物主链偶联，包括葡聚糖、支链聚（乙二醇）（PEG）和聚-L-赖氨酸。使用竞争性ELISA测定法对定义的HSA-Gal糖缀合物和猪微血管内皮细胞基质测定单体TRFA和α-半乳糖基缀合物阻断抗Gal IgG和IgM结合的能力。我们表明，分支PEG载体，与TRFA糖连接到每个分支，表现出增强的抗体阻断能力相比，TRFA，但在更高的靶抗原密度，这些简单的PEG缀合物是没有更有效的，然后在阻断抗Gal IgM抗体相互作用的等量的TRFA。相比之下，使用葡聚糖和聚-L-赖氨酸制备的支链PEG缀合物和线性缀合物的聚合物是2000至70000倍更有效的抗Gal抗体抑制剂。在一项使用非人灵长类动物的研究中，单剂量输注聚合物PEG或葡聚糖糖缀合物可显著降低食蟹猴中循环抗Gal抗体的水平，持续至少72小时。类似于这些的糖缀合物可能既可用于阻断体内抗Gal相互作用，又可用于特异性控制诱导的抗Gal免疫应答。
Porcine organs are rapidly rejected after transplantation into primate recipients due to the presence of preexisting immunoglobulins that bind to terminal galactose alpha1,3 galactose residues (alpha-galactosyl) present on porcine glycoproteins and glycolipids. Currently available immunosuppressive reagents have been largely ineffective at controlling the synthesis of these anti-Gal antibodies. Nonantigenic hapten polymers have been shown to be effective materials for blocking humoral immune responses in various model systems. We have developed a series of alpha-galactosyl glycoconjugate polymers and tested their ability to block anti-Gal antibody binding in vitro and in vivo. A galactose alpha1,3 galactose beta 1,4 GlcNAc trisaccharide free acid (TRFA) with a hexanoic acid spacer, containing five methylene groups and a carboxylic acid, was produced and coupled to a variety of polymeric backbones including dextran, branched poly(ethylene glycol) (PEG), and poly-L-lysine. The ability of monomeric TRFA and the alpha-galactosyl conjugates to block anti-Gal IgG and IgM binding was determined using a competition ELISA assay on defined HSA-Gal glycoconjugates and porcine microvascular endothelial cell substrates. We show that branched PEG carriers, with a TRFA sugar attached to each branch, exhibit enhanced antibody blocking ability compared to TRFA, but at higher target antigen densities these simple PEG conjugates are no more effective then an equivalent amount of TRFA in blocking anti-Gal IgM antibody interactions. In contrast, polymers of the branched PEG conjugates and linear conjugates made using dextran and poly-L-lysine were 2000 to 70000-fold more effective inhibitors of anti-Gal antibodies. In a study using nonhuman primates, a single dose infusion of polymeric PEG or dextran glycoconjugates dramatically reduced the level of circulating anti-Gal antibodies in cynomologus monkeys for at least 72 h. Glycoconjugates similar to these might be useful both to block antiGal interactions in vivo and to specifically control the induced anti-Gal immune response.