Department of Pediatrics, National Jewish Health, Denver, CO.
Department of Pediatrics, National Jewish Health, Denver, CO; Department of Pediatrics, University of Colorado Denver, Anschutz Medical Center, Aurora, CO.
J Cyst Fibros. 2022 Jul;21(4):637-643. doi: 10.1016/j.jcf.2022.02.011. Epub 2022 Mar 2.
A decrease in the lumacaftor-mediated increase in F508del-CFTR function and expression upon prolonged exposure to ivacaftor (VX-770) has previously been described. However, the efficacy observed with ivacaftor-containing CFTR modulator therapies in vivo is in conflict with these reports. We hypothesized that a portion of the apparent decrease in CFTR function observed after prolonged ivacaftor exposure in vitro was due to an increase in constitutive CFTR-mediated ion transport.
Human nasal epithelial (HNE) cells were obtained by brushings from three CF individuals homozygous for the F508del CFTR mutation. Differentiated epithelia were pre-treated with prolonged (24 h) exposure to either lumacaftor (VX-809; 3 µM), tezacaftor (VX-661; 3 µM), elexacaftor (VX-445; 3 µM), and/or ivacaftor (0.1-6.4 µM) or DMSO (vehicle control), and CFTR function was assayed by Ussing chamber electrophysiology.
In cells treated with lumacaftor, constitutive CFTR activity was not increased at any concentration of co-treatment with ivacaftor. Constitutive CFTR activity was also unchanged in cells treated with the combination of tezacaftor and elexacaftor. An increase in constitutive CFTR activity above the DMSO controls was only observed in cells treated with the combination of tezacaftor and elexacaftor and co-treated with at least 0.1 µM ivacaftor.
These results demonstrate that ivacaftor is a critical component in the triple combination therapy along with tezacaftor and elexacaftor to increase constitutive CFTR function. This work further elucidates the mechanism of action of the effective triple combination therapeutic that is now the primary clinical tool in treating CF.
先前已经描述过，在长时间暴露于伊伐卡托（VX-770）后，拉卡非特介导的 F508del-CFTR 功能和表达的增加会减少。然而，体内含有伊伐卡托的 CFTR 调节剂治疗的疗效与这些报告相矛盾。我们假设，在体外长时间暴露于伊伐卡托后观察到的 CFTR 功能明显下降的部分原因是组成型 CFTR 介导的离子转运增加。
通过刷拭从三个纯合 F508del CFTR 突变的 CF 个体中获得人鼻上皮（HNE）细胞。分化的上皮细胞先用拉卡非特（VX-809；3 μM）、特扎卡托（VX-661；3 μM）、埃利卡托（VX-445；3 μM）和/或伊伐卡托（0.1-6.4 μM）或 DMSO（载体对照）长时间（24 小时）预处理，然后通过 Ussing 室电生理学测定 CFTR 功能。
在用拉卡非特处理的细胞中，在任何浓度的伊伐卡托共同处理下，组成型 CFTR 活性均未增加。在用特扎卡托和埃利卡托联合处理的细胞中，组成型 CFTR 活性也没有变化。在用特扎卡托和埃利卡托联合处理且共同用至少 0.1 μM 的伊伐卡托处理的细胞中，仅观察到组成型 CFTR 活性高于 DMSO 对照的增加。
这些结果表明，伊伐卡托是与特扎卡托和埃利卡托联合的三联组合疗法中的关键组成部分，可增加组成型 CFTR 功能。这项工作进一步阐明了目前治疗 CF 的主要临床工具有效三联组合治疗的作用机制。
