Interactions between Cytosolic Phospholipase A2 Activation and Mitochondrial Reactive Oxygen Species Production in the Development of Ventilator-Induced Diaphragm Dysfunction

Cytosolic phospholipase A2 (cPLA2) has been reported to be critical for infection-induced mitochondrial reactive oxygen species (ROS) production and diaphragm dysfunction (DD). In the present study, we aim to investigate whether cPLA2 was involved in ventilator-induced diaphragm dysfunction (VIDD). Our results showed that mechanical ventilation (MV) induced cPLA2 activation in the diaphragm with excessive mitochondrial ROS generation and muscle weakness. Specific inhibition of cPLA2 with CDIBA resulted in decreased mitochondrial ROS levels and improved diaphragm forces. In addition, mitochondria-targeted antioxidant MitoTEMPO attenuated ventilator-induced mitochondrial oxidative stress and downregulated cPLA2 activation in vivo. Both CDIBA and MitoTEMPO were able to attenuate protein degradation, muscle atrophy, and weakness following prolonged MV. Furthermore, laser Doppler imaging showed that MV decreased diaphragm tissue perfusion and induced subsequent hypoxia. An in vitro study also demonstrated a positive association between cPLA2 activation and mitochondrial ROS generation in C2C12 cells cultured under hypoxic condition. Collectively, our study showed that cPLA2 activation positively interacts with mitochondrial ROS generation in the development of VIDD, and ventilator-induced diaphragm hypoxia serves as a possible contributor to this positive feedback loop.