人类非洲锥虫病(HAT)是一种被忽视的寄生虫病,在撒哈拉以南非洲继续存在。如果不加以治疗是致命的。疾病的第一阶段与外周中寄生虫的存在有关,第二阶段与CNS中寄生虫的存在有关。CNS阶段HAT的治疗需要药物穿过血脑屏障(BBB)。Eflornithine是一种氨基酸类似物,可单独或与硝呋替莫联合用于治疗第二阶段HAT冈比亚。最近的研究已经确定,依氟鸟氨酸在寄生虫(锥虫)中的积累涉及氨基酸转运蛋白(布鲁氏锥虫AAT6)。在这项研究中,我们测试了依氟鸟氨酸使用阳离子氨基酸转运系统穿越BBB的假设。我们特别关注system-y+和system-B0,+。为此,我们利用专业数据库比较了相关分子的物理化学特征和BBB的体外模型,以探索依氟鸟氨酸递送到CNS的机制。我们的结果证实,依氟鸟氨酸与内源性氨基酸有关,鸟氨酸.在pH7.4,依氟鸟氨酸主要是(92.39%)两性离子(偶极)氨基酸,鸟氨酸主要是(99.08%)阳离子(三极)氨基酸。此外,依氟鸟氨酸在pH7.4时的总电荷分布(0.073)远小于鸟氨酸(0.99)。进一步的结果表明,依氟鸟氨酸利用可饱和转运机制穿过hCMEC/D3细胞膜,并且转运被包括鸟氨酸在内的其他氨基酸的存在抑制。依氟鸟氨酸转运也不依赖钠,对y+系统抑制剂敏感,但不是B0,+-系统抑制剂.依氟鸟氨酸的转运也被戊脒抑制,提示在该细胞系中表达的有机阳离子转运蛋白(OCT)的转运。我们证实了Y+系统蛋白的表达,CAT1和B0,+-系统蛋白,ATB0,+,在hCMEC/D3细胞中。我们得出结论,依氟鸟氨酸使用阳离子氨基酸转运蛋白,系统y+,和OCT穿过BBB。这项研究强调了系统y+递送药物的潜力,包括依氟鸟氨酸,跨越血脑屏障来治疗脑部疾病。
Human African Trypanosomiasis (HAT) is a neglected parasitic disease that continues to persist in sub-Saharan Africa. It is fatal if untreated. The first stage of the disease is associated with the presence of the parasite in the periphery and the second stage with the presence of the parasites in the CNS. The treatment of CNS stage HAT requires the drugs to cross the blood-brain barrier (BBB).
Eflornithine is an amino acid analogue that is used to treat second stage HAT gambiense both alone and in combination with nifurtimox. Recent studies have identified that accumulation of eflornithine into the parasites (trypanosomes) involves the amino acid transporter (Trypanosoma brucei AAT6). In this study we tested the hypothesis that
eflornithine uses a cationic amino acid transport system to cross the BBB. We particularly focused on system-y+ and system-B0,+. To do this we utilized specialist databases to compare the physicochemical characteristics of relevant molecules and an in vitro model of the BBB to explore the mechanisms of eflornithine delivery into the CNS. Our results confirmed that
eflornithine is related to the endogenous amino acid, ornithine. At pH 7.4,
eflornithine is predominately (92.39%) a zwitterionic (dipolar) amino acid and ornithine is predominately (99.08%) a cationic (tripolar) amino acid. In addition, the gross charge distribution at pH 7.4 of eflornithine is much smaller (+0.073) than that of ornithine (+0.99). Further results indicated that
eflornithine utilized a saturable transport mechanism(s) to cross the hCMEC/D3 cell membranes and that transport was inhibited by the presence of other amino acids including ornithine. Eflornithine transport was also sodium-independent and sensitive to a y+-system inhibitor, but not a B0,+-system inhibitor. Eflornithine transport was also inhibited by pentamidine, suggestive of transport by organic cation transporters (OCT) which are expressed in this cell line. We confirmed expression of the y+-system protein, CAT1, and the B0,+-system protein, ATB0,+, in the hCMEC/D3 cells. We conclude that eflornithine uses the cationic amino acid transporter, system y+, and OCT to cross the BBB. This research highlights the potential of system-y+ to deliver drugs, including eflornithine, across the BBB to treat brain diseases.