BINDING, INTERNALIZATION, AND DEGRADATION OF MANNOSE-TERMINATED GLUCOCEREBROSIDASE BY MACROPHAGES
BINDING, INTERNALIZATION, AND DEGRADATION OF MANNOSE-TERMINATED GLUCOCEREBROSIDASE BY MACROPHAGES
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DOI：
10.1172/jci116409
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发表时间：
1993-05-01
影响因子：
15.9
通讯作者：
BEUTLER, E
中科院分区：
文献类型：
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作者：
SATO, Y;BEUTLER, E
甘露糖封端的葡糖脑苷脂酶（阿葡糖苷酶; Ceredase（R））被设计用于戈谢病的酶替代治疗，以利用甘露糖受体介导的巨噬细胞内吞作用。为了为设计酶替代治疗方案提供合理的依据，我们研究了小鼠和人巨噬细胞对阿葡糖苷酶的体外结合、摄取和降解。发现这两种细胞每个细胞都有大约500，000个甘露糖依赖性α-葡糖苷酶受体，0 ℃时K（d）为10（-7）M。相比之下，甘露糖-牛血清白蛋白（甘露糖-BSA）（甘露糖受体的经典配体）的结合位点数仅约为20，000，K（d）为10（-8）M。阿葡糖苷酶也以甘露糖依赖性方式与缺乏甘露糖-BSA结合能力的细胞（如Cos-1细胞、内皮细胞和外周血单核细胞）结合。巨噬细胞与阿葡糖苷酶的结合主要由与结合甘露糖-BSA的经典甘露糖受体不同的受体介导，这一事实已通过差异抑制剂（即，α-甲基-葡萄糖苷、岩藻糖和甘露糖-BSA，并且不依赖于Ca 2+。37 ℃时巨噬细胞对alglucerase的摄取呈浓度依赖性，在10（-6）M时达到半数最大值。然而，在浓度为10（-7）M时，仅0.5%的添加的阿葡糖苷酶被掺入巨噬细胞中，约50%的吸收的阿葡糖苷酶被快速释放到培养基中。内皮细胞还表现出甘露糖依赖性结合和摄取阿葡糖苷酶，因此可能占输注阿葡糖苷酶的很大比例。我们的数据表明，只有少量的阿葡糖苷酶被有效地输送到巨噬细胞，更有效地靶向酶可能有一个显着的治疗优势，甘露糖终止的葡萄糖脑苷脂酶。
Mannose-terminated glucocerebrosidase (alglucerase; Ceredase(R)) was designed for enzyme replacement therapy in Gaucher disease to take advantage of mannose receptor-mediated endocytosis by macrophages. To provide a rational basis for designing enzyme replacement therapy protocols, we examined the in vitro binding, uptake, and degradation of alglucerase by murine and human macrophages. Both were found to have approximately 500,000 mannose-dependent receptors for alglucerase per cell with a K(d) of 10(-7) M at 0-degrees-C. In contrast, the number of binding sites for mannose-bovine serum albumin (mannose-BSA), the classical ligand for the mannose receptor, was only approximately 20,000 with a K(d) of 10(-8) M. Alglucerase was also bound in a mannose-dependent manner by cells that lack the capacity to bind mannose-BSA, such as Cos-1 cells, endothelial cells, and peripheral blood monocytes. The fact that the binding of alglucerase by macrophages was mediated principally by a receptor distinct from the classical mannose receptor that binds mannose-BSA was confirmed by differential inhibitors, viz., alpha-methyl-glucoside, fucose, and mannose-BSA, and by its independence on Ca2+.Uptake of alglucerase by macrophages at 37-degrees-C was concentration dependent and half maximal at 10(-6) M. However, at a concentration of 10(-7) M, only 0.5% of the added alglucerase was incorporated into macrophages and approximately 50% of the alglucerase taken up was quickly released into the medium. Endothelial cells also manifest mannose-dependent binding and uptake of alglucerase and may therefore account for a large proportion of the infused alglucerase. Our data suggest that only a small amount of the alglucerase administered is effectively delivered to macrophages and that a more efficiently targeted enzyme might have a marked therapeutic advantage over mannose-terminated glucocerebrosidase.