Inhibition of the Foxo3/Txnip Axis Alleviates Ventilator-Induced Diaphragmatic Dysfunction by Downregulating MuRF1

Abstract

Ventilator-induced diaphragm dysfunction (VIDD) is one of the main causes of weaning from mechanical ventilation (MV). The forkhead box O3 (Foxo3) has been identified as being involved in regulating the contractile function of skeletal muscle. This study aimed to figure out the regulatory role and mechanism of Foxo3 on VIDD. The mouse myoblast C2C12 cells were stimulated using different intensities of stress to mimic the in-vitro VIDD model. 3- (4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and TdT-mediated dUTP nick end labeling (TUNEL) assays were applied to check cell viability and apoptosis, respectively. Cellular inflammation and oxidative stress levels were evaluated by measuring cellular inflammatory factors (IL-1β and TNF-α) and oxidative stress markers (SOD and MDA). The release of oxygen species (ROS) was assayed by cellular immunofluorescence. The expression of apoptosis-associated proteins (Bax and Bcl-2), Gpx4, Slc7a11, Ptgs2, Foxo3, Txnip, Murf1, Atrogin-1, Nlrp3, Asc, and Caspase1 was gauged using Western blot. The rats with or without MV therapy were treated with the Foxo3 inhibitor Carbenoxolone (CBX) to characterize the impact of Foxo3 on VIDD. Stress stimulation dampened myogenic cell viability, boosted apoptosis, inflammation, oxidative stress, and ROS release, and activated the expression of Foxo3 and Txnip pathways. Overexpression of Txnip or Murf1 lessened the protective effect of FOxO3 inhibition on myoblasts. Downregulation of Txnip or Murf1 mitigated myoblasts dysfunction that was induced by Foxo3 overexpression. In vivo, inhibition of Foxo3 mitigated MV-induced diaphragmatic atrophy and reduced contractility, inflammation, and oxidative stress in rats. Inhibition of Foxo3 eased VIDD by downregulating Txnip and Murf1.

Keywords: Foxo3; MuRF1; Myoblast; Txnip; Ventilator-induced diaphragm dysfunction.