Hyperoxia treatment of TREK-1/TREK-2/TRAAK-deficient mice is associated with a reduction in surfactant proteins

Am J Physiol Lung Cell Mol Physiol. 2017 Dec 1;313(6):L1030-L1046. doi: 10.1152/ajplung.00121.2017. Epub 2017 Aug 24.

Abstract

We previously proposed a role for the two-pore domain potassium (K2P) channel TREK-1 in hyperoxia (HO)-induced lung injury. To determine whether redundancy among the three TREK isoforms (TREK-1, TREK-2, and TRAAK) could protect from HO-induced injury, we now examined the effect of deletion of all three TREK isoforms in a clinically relevant scenario of prolonged HO exposure and mechanical ventilation (MV). We exposed WT and TREK-1/TREK-2/TRAAK-deficient [triple knockout (KO)] mice to either room air, 72-h HO, MV [high and low tidal volume (TV)], or a combination of HO + MV and measured quasistatic lung compliance, bronchoalveolar lavage (BAL) protein concentration, histologic lung injury scores (LIS), cellular apoptosis, and cytokine levels. We determined surfactant gene and protein expression and attempted to prevent HO-induced lung injury by prophylactically administering an exogenous surfactant (Curosurf). HO treatment increased lung injury in triple KO but not WT mice, including an elevated LIS, BAL protein concentration, and markers of apoptosis, decreased lung compliance, and a more proinflammatory cytokine phenotype. MV alone had no effect on lung injury markers. Exposure to HO + MV (low TV) further decreased lung compliance in triple KO but not WT mice, and HO + MV (high TV) was lethal for triple KO mice. In triple KO mice, the HO-induced lung injury was associated with decreased surfactant protein (SP) A and SPC but not SPB and SPD expression. However, these changes could not be explained by alterations in the transcription factors nuclear factor-1 (NF-1), NKX2.1/thyroid transcription factor-1 (TTF-1) or c-jun, or lamellar body levels. Prophylactic Curosurf administration did not improve lung injury scores or compliance in triple KO mice.

Keywords: ALI; ARDS; TRAAK; TREK; acute lung injury; acute respiratory distress syndrome; lung; lung injury; mechanical stretch; surfactant hyperoxia; ventilator-associated injury.

MeSH terms

  • Animals
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / genetics
  • Hyperoxia / genetics
  • Hyperoxia / metabolism*
  • Hyperoxia / pathology
  • Lipopolysaccharides / toxicity
  • Lung Injury / genetics
  • Lung Injury / metabolism*
  • Lung Injury / pathology
  • Mice
  • Mice, Knockout
  • Potassium Channels / deficiency*
  • Potassium Channels, Tandem Pore Domain / deficiency*
  • Pulmonary Surfactant-Associated Proteins / biosynthesis*
  • Pulmonary Surfactant-Associated Proteins / genetics
  • Transcription Factors / genetics
  • Transcription Factors / metabolism

Substances

  • Kcnk10 protein, mouse
  • Kcnk4 protein, mouse
  • Lipopolysaccharides
  • Potassium Channels
  • Potassium Channels, Tandem Pore Domain
  • Pulmonary Surfactant-Associated Proteins
  • Transcription Factors
  • potassium channel protein TREK-1