Tournay C, Courtoy P J, Marodi L, Totté P, Werenne J, Jacquet A, Garcia-Quintana L, Bollen A, Moguilevsky N
Applied Genetics, University of Brussels, Nivelles, Belgium.
DNA Cell Biol. 1996 Aug;15(8):617-24. doi: 10.1089/dna.1996.15.617.
A chimeric antibody-like molecule consisting of the human myeloperoxidase (rMPO) fused to the second and third constant-sequence (CH2 and CH3) Fc domains of human immunoglobulin G-1 has been constructed and expressed in Chinese hamster ovary (CHO) cells. This fusion molecule was designed to combine the binding specificity of Fc with the antimicrobial properties of rMPO. The rMPO-Fc fusion dimerized through the Fc fragment, while retaining the enzymatic activity of rMPO. The chimeric molecule was glycosylated and most of the propeptide was eliminated, indicating a better processing of the polypeptide than for rMPO alone. Both rMPO and rMPO-Fc bound to and were internalized by macrophage-like U937 promonocytic cells. Unexpectedly, the chimera failed to bind to the Fc receptor but interacted with a higher affinity than rMPO with the same binding sites. The presence of the Fc fragment in the chimera, in addition, did not extend the plasma half-life of the fusion protein. In vitro, rMPO-Fc exhibited a stronger killing effect than rMPO toward Candida albicans in the presence of either H202 alone or human macrophages. In vivo, rMPO-Fc similarly conferred a better protection than rMPO in a lethal model of murine cowdriosis. These properties could be related to the Fc-induced dimerization of the fusion protein in CHO cells.
一种嵌合抗体样分子已构建成功并在中国仓鼠卵巢（CHO）细胞中表达，该分子由人髓过氧化物酶（rMPO）与人免疫球蛋白G-1的第二和第三恒定序列（CH2和CH3）Fc结构域融合而成。这种融合分子旨在将Fc的结合特异性与rMPO的抗菌特性相结合。rMPO-Fc融合体通过Fc片段二聚化，同时保留rMPO的酶活性。该嵌合分子进行了糖基化修饰，且大部分前肽被去除，这表明与单独的rMPO相比，该多肽的加工过程更好。rMPO和rMPO-Fc都能与巨噬细胞样U937前单核细胞结合并被其内化。出乎意料的是，该嵌合体未能与Fc受体结合，但与相同结合位点的亲和力高于rMPO。此外，嵌合体中Fc片段的存在并未延长融合蛋白的血浆半衰期。在体外，在单独存在H2O2或人巨噬细胞的情况下，rMPO-Fc对白色念珠菌的杀伤作用比rMPO更强。在体内，在鼠巴贝斯虫病致死模型中，rMPO-Fc同样比rMPO提供了更好的保护。这些特性可能与Fc诱导的融合蛋白在CHO细胞中的二聚化有关。
