Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas (IPBLN-CSIC), Parque Tecnológico de Ciencias de la Salud, Avda. del Conocimiento s/n, 18100 Armilla, Granada, Spain.
Antimicrob Agents Chemother. 2011 Aug;55(8):3838-44. doi: 10.1128/AAC.00065-11. Epub 2011 Jun 6.
Although oral miltefosine represented an important therapeutic advance in the treatment of leishmaniasis, the appearance of resistance remains a serious threat. LMDR1/LABCB4, a P-glycoprotein-like transporter included in the Leishmania ABC (ATP-binding cassette) family, was the first molecule shown to be involved in experimental miltefosine resistance. LMDR1 pumps drugs out of the parasite, thereby decreasing their intracellular accumulation. Sitamaquine, another promising oral drug for leishmaniasis, is currently in phase 2b clinical trials. The physicochemical features of this drug suggested to us that it could be considered for use as an LMDR1 inhibitor. Indeed, we report herein that nonleishmanicidal concentrations of sitamaquine reverse miltefosine resistance in a multidrug resistance Leishmania tropica line that overexpresses LMDR1. This reversal effect is due to modulation of the LMDR1-mediated efflux of miltefosine. In addition, sitamaquine is not a substrate of LMDR1, as this transporter does not affect sitamaquine accumulation or sensitivity in the parasite. Likewise, we show that ketoconazole, another oral leishmanicidal drug known to interact with ABC transporters, is also able to reverse LMDR1-mediated miltefosine resistance, although with a lower efficiency than sitamaquine. Molecular docking on a three-dimensional homology model of LMDR1 showed different preferential binding sites for each substrate-inhibitor pair, thus explaining this different behavior. Finally, we show that sitamaquine is also able to modulate the antimony resistance mediated by MRPA/LABCC3, another ABC transporter involved in experimental and clinical antimony resistance in this parasite. Taken together, these data suggest that the combination of sitamaquine with miltefosine or antimony could avoid the appearance of resistance mediated by these membrane transporters in Leishmania.
虽然口服米替福新在治疗利什曼病方面代表了一个重要的治疗进展，但耐药性的出现仍然是一个严重的威胁。LMDR1/LABCB4，一种包含在 Leishmania ABC（ATP 结合盒）家族中的 P-糖蛋白样转运体，是第一个被证明与实验性米替福新耐药性有关的分子。LMDR1 将药物泵出寄生虫，从而减少其细胞内积累。另一种有前途的利什曼病口服药物西他喹啉目前正在进行 2b 期临床试验。该药物的物理化学特性使我们认为它可以被考虑用作 LMDR1 抑制剂。事实上，我们在此报告，非杀利什曼原虫浓度的西他喹啉可逆转过度表达 LMDR1 的多药耐药 Leishmania tropica 系中的米替福新耐药性。这种逆转作用归因于 LMDR1 介导的米替福新外排的调节。此外，西他喹啉不是 LMDR1 的底物，因为这种转运体不会影响 LMDR1 在寄生虫中的积累或敏感性。同样，我们表明，酮康唑，另一种已知与 ABC 转运体相互作用的口服利什曼病杀生物，也能够逆转 LMDR1 介导的米替福新耐药性，尽管效率低于西他喹啉。对 LMDR1 三维同源模型的分子对接显示，每个底物-抑制剂对都有不同的优先结合位点，从而解释了这种不同的行为。最后，我们表明，西他喹啉也能够调节由另一种 ABC 转运体 MRPA/LABCC3 介导的锑耐药性，这种转运体也参与了该寄生虫的实验和临床锑耐药性。总之，这些数据表明，西他喹啉与米替福新或锑的联合使用可以避免这些膜转运体介导的利什曼原虫耐药性的出现。
