Hyperbaric oxygen therapy suppresses hypoxia and reoxygenation injury to retinal pigment epithelial cells through activating peroxisome proliferator activator receptor-alpha signalling

Retinal ischemia followed by reperfusion (IR) is a common cause of many ocular disorders, such as age-related macular degeneration (AMD), which leads to blindness in the elderly population, and proper therapies remain unavailable. Retinal pigment epithelial (RPE) cell death is a hallmark of AMD. Hyperbaric oxygen (HBO) therapy can improve IR tissue survival by inducing ischemic preconditioning responses. We conducted an in vitro study to examine the effects of HBO preconditioning on oxygen–glucose deprivation (OGD)-induced IR-injured RPE cells. RPE cells were treated with HBO (100% O₂ at 3 atmospheres absolute for 90 min) once a day for three consecutive days before retinal IR onset. Compared with normal cells, the IR-injured RPE cells had lower cell viability, lower peroxisome proliferator activator receptor-alpha (PPAR-α) expression, more severe oxidation status, higher blood-retinal barrier disruption and more elevated apoptosis and autophagy rates. HBO preconditioning increased PPAR-α expression, improved cell viability, decreased oxidative stress, blood-retinal barrier disruption and cellular apoptosis and autophagy. A specific PPAR-α antagonist, GW6471, antagonized all the protective effects of HBO preconditioning in IR-injured RPE cells. Combining these observations, HBO therapy can reverse OGD-induced RPE cell injury by activating PPAR-α signalling.