Ventilator-induced lung injury is associated with endothelial cell mitochondrial fission
Abstract
Introduction and Objective. Mechanical ventilation (MV) is the only treatment for sepsis-induced acute respiratory distress syndrome (ARDS). Unfortunately, MV effectiveness is variable and can exacerbate lung injury. Recent studies report mitochondrial dysfunction as crucial to the progression of ARDS. Mitochondria are dynamic organelles that constantly fuse and separate to regulate their function, termed mitochondrial dynamics. Therefore, this study aimed to determine the mitochondrial effects MV exerts on the endothelium to determine if the modulation of mitochondrial dynamics is a plausible therapeutic strategy to mitigate damage from MV. Methods. Human lung microvascular cells (HLMVEC) were subjected to 4-12 hours of 18% cyclic stretch, mimicking the same degree of stretch that is exerted on pulmonary endothelial cells during MV. To assess mitochondrial function, mitochondrial membrane depolarization, bioenergetics, and dynamics were measured, along with overall cell generation of reactive species and protein nitration. C57 mice were either intravenously injected with 5mg/kg of siDrp1 (siRNA ID: s92137) for 72h or intraperitoneally treated with 1mg/kg of the Drp1 inhibitor, P110, for 1h. Mice were then mechanically ventilated for 4-hours (tidal volume = 30 mL/kg). Statistical analysis: means ± SEM was calculated and compared by the t-test. ANOVA for repeated measures was used when multiple comparisons were made with Student-Newman-Keuls post hoc testing. Results. Subjecting HLMVEC to stretch reduced basal respiration (30%, p. Silencing the pro-fission mediator, Drp1 (dynamin-related protein 1) using siRNA prior to stretch prevented the reductions in mitochondrial bioenergetics and protected against the fission phenotype. We found that stretch increased the nitration-mediated activation of RhoA, increasing its activity by 29% (p=0.0089) and subsequently activated Drp1, by more than doubling the phosphorylation at serine616(p=0.0192). In mice, silencing Drp1 was protective against ventilator-induced inflammatory lung injury. siDrp1 treatment reduced lung inflammation, edema, and lung injury by 54%, 73%, and 32%, respectively. Conclusions-Implications. Fission-dependent disruption of mitochondrial function is essential in the development of ventilator-induced lung injuries and preserving mitochondrial dynamics is a potential therapeutic strategy to improve MV outcomes.
Keywords
Mechanical ventilation, mitochondria, acute respiratory distress syndrome, endothelial cell
Presentation Type
Poster Presentation
Ventilator-induced lung injury is associated with endothelial cell mitochondrial fission
Introduction and Objective. Mechanical ventilation (MV) is the only treatment for sepsis-induced acute respiratory distress syndrome (ARDS). Unfortunately, MV effectiveness is variable and can exacerbate lung injury. Recent studies report mitochondrial dysfunction as crucial to the progression of ARDS. Mitochondria are dynamic organelles that constantly fuse and separate to regulate their function, termed mitochondrial dynamics. Therefore, this study aimed to determine the mitochondrial effects MV exerts on the endothelium to determine if the modulation of mitochondrial dynamics is a plausible therapeutic strategy to mitigate damage from MV. Methods. Human lung microvascular cells (HLMVEC) were subjected to 4-12 hours of 18% cyclic stretch, mimicking the same degree of stretch that is exerted on pulmonary endothelial cells during MV. To assess mitochondrial function, mitochondrial membrane depolarization, bioenergetics, and dynamics were measured, along with overall cell generation of reactive species and protein nitration. C57 mice were either intravenously injected with 5mg/kg of siDrp1 (siRNA ID: s92137) for 72h or intraperitoneally treated with 1mg/kg of the Drp1 inhibitor, P110, for 1h. Mice were then mechanically ventilated for 4-hours (tidal volume = 30 mL/kg). Statistical analysis: means ± SEM was calculated and compared by the t-test. ANOVA for repeated measures was used when multiple comparisons were made with Student-Newman-Keuls post hoc testing. Results. Subjecting HLMVEC to stretch reduced basal respiration (30%, p. Silencing the pro-fission mediator, Drp1 (dynamin-related protein 1) using siRNA prior to stretch prevented the reductions in mitochondrial bioenergetics and protected against the fission phenotype. We found that stretch increased the nitration-mediated activation of RhoA, increasing its activity by 29% (p=0.0089) and subsequently activated Drp1, by more than doubling the phosphorylation at serine616(p=0.0192). In mice, silencing Drp1 was protective against ventilator-induced inflammatory lung injury. siDrp1 treatment reduced lung inflammation, edema, and lung injury by 54%, 73%, and 32%, respectively. Conclusions-Implications. Fission-dependent disruption of mitochondrial function is essential in the development of ventilator-induced lung injuries and preserving mitochondrial dynamics is a potential therapeutic strategy to improve MV outcomes.