Roflumilast inhibits neuronal ferroptosis via AMPK/Nrf2/HO-1 signaling and promotes motor function recovery after spinal cord injury in rats

Abstract

Spinal cord injury (SCI) is a serious central nervous system disease. Ferroptosis is one of the major causes of spinal cord neurological loss, and targeting ferroptosis is a promising therapeutic strategy. Roflumilast has shown promising applications in the treatment of neurological diseases due to its potent anti-inflammatory and anti-oxidative stress effects. This study aimed to investigate whether roflumilast could inhibit neuronal ferroptosis to improve motor function after SCI in rats. In vitro experiments, we found that roflumilast significantly increased cell survival in an in vitro ferroptosis model, improved mitochondrial function, reduced intracellular iron, reactive oxygen species (ROS), and lipid peroxides accumulation as well as the expression of the pro-ferroptosis proteins, long-chain acyl-coenzyme A synthase 4 (ACSL4), and prostaglandin-endoperoxide synthase 2 (PTGS2), and increased the expression of ferroptosis-inhibitory protein glutathione peroxidase 4 (GPX4), and ferritin heavy chain 1 (FTH1) expression. Mechanistically, these protective effects were achieved by activating AMP-dependent protein kinase (AMPK)/nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling and were attenuated when AMPK signaling was blocked. In vivo experiments, roflumilast attenuated spinal cord tissue damage, increased the number of motor neuron survivors, and improved motor function after SCI in rats. Overall, activation of AMPK/Nrf2/HO-1 signaling by roflumilast attenuated neuronal ferroptosis and improved motor function after SCI in rats.