Parasite Therapeutics Research Group, School of Biological Sciences, Medical Biology Centre, The Queen's University of Belfast, 97 Lisburn Road, Belfast, BT9 7BL, Northern Ireland.
Parasitology. 2013 Sep;140(10):1287-303. doi: 10.1017/S0031182013000759. Epub 2013 Jun 12.
A study was carried out to investigate whether the action of triclabendazole sulphoxide (TCBZ.SO) against the liver fluke, Fasciola hepatica is altered by inhibition of P-glycoprotein (Pgp)-linked drug efflux pumps. The Oberon TCBZ-resistant and Cullompton TCBZ-susceptible fluke isolates were used for this in vitro study and the Pgp inhibitor selected was R(+)-verapamil [R(+)-VPL]. For experiments with the Oberon isolate, flukes were incubated for 24 h with either R(+)-VPL (1×10-4 m) on its own, TCBZ.SO (15 μg mL-1) alone, a combination of R(+)-VPL (1×10-4 m) plus TCBZ.SO (15 μg mL-1), TCBZ.SO (50 μg mL-1) on its own, or a combination of TCBZ.SO (50 μg mL-1) plus R(+)-VPL (1×10-4 m). They were also incubated in TCBZ.SO (50 μg mL-1) alone or in combination with R(+)-VPL (1×10-4 m) until they became inactive; and in TCBZ.SO (50 μg mL-1) alone for a time to match that of the combination inactivity time. Flukes from the Cullompton isolate were treated with either TCBZ.SO (50 μg mL-1) alone or in combination with R(+)-VPL (1×10-4 m) until they became inactive, or with TCBZ.SO (50 μg mL-1) alone time-matched to the combination inactivity time. Morphological changes resulting from drug treatment and following Pgp inhibition were assessed by means of scanning electron microscopy. Incubation in R(+)-VPL alone had a minimal effect on either isolate. TCBZ.SO treatment had a relatively greater impact on the TCBZ-susceptible Cullompton isolate. When R(+)-VPL was combined with TCBZ.SO in the incubation medium, however, the surface disruption to both isolates was more severe than that seen after TCBZ.SO treatment alone; also, the time taken to reach inactivity was shorter. More significantly, though, the potentiation of drug activity was greater in the Oberon isolate; also, it was more distinct at the higher concentration of TCBZ.SO. So, the Oberon isolate appears to be particularly sensitive to efflux pump inhibition. The results of this study suggest that enhanced drug efflux in the Oberon isolate may be involved in the mechanism of resistance to TCBZ.
一项研究旨在探讨三氯苯达唑亚砜（TCBZ.SO）对肝片吸虫（Fasciola hepatica）的作用是否因 P 糖蛋白（Pgp）相关药物外排泵的抑制而改变。本体外研究采用了奥伯龙 TCBZ 耐药株和卡伦顿 TCBZ 敏感株，并选择了 Pgp 抑制剂 R(+)-维拉帕米[R(+)-VPL]。对于奥伯龙株的实验，将吸虫在单独的 R(+)-VPL（1×10-4 m）、单独的 TCBZ.SO（15 μg mL-1）、R(+)-VPL（1×10-4 m）加 TCBZ.SO（15 μg mL-1）、单独的 TCBZ.SO（50 μg mL-1）或 TCBZ.SO（50 μg mL-1）加 R(+)-VPL（1×10-4 m）中孵育 24 小时。它们还在 TCBZ.SO（50 μg mL-1）单独或与 R(+)-VPL（1×10-4 m）联合孵育直至失活；并在 TCBZ.SO（50 μg mL-1）中单独孵育一段时间以匹配联合失活时间。来自卡伦顿株的吸虫用 TCBZ.SO（50 μg mL-1）单独或与 R(+)-VPL（1×10-4 m）联合孵育直至失活，或与单独的 TCBZ.SO（50 μg mL-1）孵育时间与联合失活时间相匹配。通过扫描电子显微镜评估药物处理和 Pgp 抑制后产生的形态变化。单独孵育 R(+)-VPL 对两种株系的影响都很小。TCBZ.SO 处理对 TCBZ 敏感的卡伦顿株系的影响相对较大。然而，当 R(+)-VPL 与 TCBZ.SO 一起加入孵育培养基中时，与 TCBZ.SO 单独处理相比，两种株系的表面破坏更为严重，达到失活所需的时间也更短。更重要的是，奥伯龙株系的药物活性增强更为明显；此外，在较高的 TCBZ.SO 浓度下更为明显。因此，奥伯龙株系似乎对外排泵抑制特别敏感。这项研究的结果表明，奥伯龙株系中药物外排的增强可能参与了对 TCBZ 的耐药机制。
