CFTR correction with lumacaftor/ivacaftor reduced the mitochondrial fragmentation in cystic fibrosis cultured epithelial cells

Abstract

The impairment of the CFTR channel, a cAMP-activated chloride(Cl-) channel responsible for cystic fibrosis (CF), has been associated with a variety of mitochondrial alterations. Recently, we reportedan increase in mitochondrial fragmentation induced by the inhibitionof the CFTR activity. The cAMP treatment to stimulate the CFTRactivity worsen this phenotype in CF cells. Here, we analysed themitochondrial network in CF cells treated with the CFTR modulatorsLumacaftor (VX-809)/Ivacaftor (VX-770) VX-809 act as pharmacological chaperone, increasing the amount of CFTR at the cell membrane surface; while VX-770 increase the activation of the CFTR.Single, combined and sequential treatments with VX-809 (10 μM,CFTR corrector) and VX-770 (10, 1 and 0.1 μM, CFTR enhancer)were performed in IB3-1 cells (CF cells). Also, cAMP was tested asa CFTR stimulator to compare its effect with VX-770. Mitochondriawere labelled with MitoTracker Orange, imaged by confocal microscopy, and analysed with Mitochondrial Network Analysis (MiNA)plugin for Fiji. A single treatment with VX-80948 h, but not with VX770, reduced the mitochondrial fragmentation in IB3-1 cells, whilea combined treatment with VX-809/ VX-770 for 48 h had no effect.However, the preincubation with VX-809 24 h previous to VX-770 foranother 24 h reduced significantly the mitochondrial fragmentation.Similar results were observed using cAMP to stimulate the CFTRactivity. These results suggest that CFTR potentiators could impairthe mitochondrial dynamics when the CFTR is not expressed onthe membrane surface. Further research is needed to identify themechanisms involved in this regulation to improve the therapy byusing these drugs.