Chakraborty P, Bhaduri A N, Das P K
Leishmania Group, Indian Institute of Chemical Biology, Calcutta.
J Protozool. 1990 Sep-Oct;37(5):358-64. doi: 10.1111/j.1550-7408.1990.tb01158.x.
Methotrexate (MTX) coupled to mannosyl bovine serum albumin (BSA) was taken up efficiently through the mannosyl receptors present on macrophages. Binding experiments indicate that conjugation does not decrease the affinity of the neoglycoprotein for its cell surface receptor. The drug conjugate eliminated intracellular amastigotes of Leishmania donovani in mouse peritoneal macrophages about 100 times more efficiently than free drug on the basis of 50% inhibitory dose. Inhibitory effect of the conjugate was directly proportional to the density of sugar on the neoglycoprotein carrier. Colchicine and monensin, inhibitors of receptor-mediated endocytosis, can prevent the leishmanicidal effect of the conjugate. Antileishmanial effect of the conjugate can be competitively inhibited by mannose-BSA and mannan. In a murine model of experimental visceral leishmaniasis the drug conjugate reduced the spleen parasite burden by more than 85% in a 30-day model whereas the same concentration of free drug caused little effect. These results indicate that MTX-neoglycoprotein conjugate binds specifically to macrophages, and is internalized and degraded in lysosomes releasing the active drug to act on Leishmania parasites. These results also represent the potential for a general approach to intracellular targeting of clinical agents for macrophage-associated disorders.
与甘露糖基牛血清白蛋白（BSA）偶联的甲氨蝶呤（MTX）可通过巨噬细胞上存在的甘露糖基受体被有效摄取。结合实验表明，偶联作用不会降低新糖蛋白对其细胞表面受体的亲和力。基于50%抑制剂量，药物偶联物清除小鼠腹腔巨噬细胞中杜氏利什曼原虫的细胞内无鞭毛体的效率比游离药物高约100倍。偶联物的抑制作用与新糖蛋白载体上糖的密度成正比。秋水仙碱和莫能菌素是受体介导的内吞作用的抑制剂，可阻止偶联物的杀利什曼原虫作用。偶联物的抗利什曼原虫作用可被甘露糖-BSA和甘露聚糖竞争性抑制。在实验性内脏利什曼病的小鼠模型中，在30天的模型中，药物偶联物使脾脏寄生虫负荷降低了85%以上，而相同浓度的游离药物几乎没有效果。这些结果表明，MTX-新糖蛋白偶联物特异性结合巨噬细胞，并在溶酶体中内化和降解，释放出活性药物作用于利什曼原虫。这些结果也代表了一种针对巨噬细胞相关疾病的临床药物细胞内靶向的通用方法的潜力。
