Hyperbaric oxygen treatment reverses radiation induced pro-fibrotic and oxidative stress responses in a rat model

Radiotherapy is effective in the treatment of tumors in the pelvic area but is associated with side effects such as cystitis and proctitis. Hyperbaric Oxygen Therapy (HBOT) has emerged as a treatment modality for radiation-induced side effects. In a rat model for radiation cystitis, we studied the effects of HBOT on oxidative stress and pro-fibrotic factors. Sedated Sprague-Dawley rats underwent bladder irradiation of 20Gy with and without 20 sessions of HBOT during a fortnight. Control animals were treated with and without HBOT. All four groups of animals were euthanized 28 days later. Histopathological examinations, immunohistochemistry and quantitative polymerase chain reaction (qPCR) were used to analyze changes in oxidative stress (8-OHdG), anti-oxidative responses (SOD-1, SOD2, HO-1 and NRFα) and a panel of Th1-type and Th2-type cytokines (IL-1β, IL-4, IL-5, IL-6, IL-10, IL-13, TNF-α, TGF-β, IFN-γ) in the urinary bladder. Bladder irradiation increased the expression of 8-OHdG, SOD2, HO-1, NRFα, IL-10, TNF-α and tended to increase TGF-β. These changes were completely reversed by HBOT while HBOT in control animals had no effects on the studied markers for oxidative stress, anti-oxidative responses and Th1-type and Th2-type cytokines. Radiation induced a significant elevation of oxidative stress, antioxidants and pro-fibrotic factors in our animal model for radiation cystitis that were completely reversed and normalized by HBOT. Our findings indicate that HBOT may prevent radiation-induced changes by affecting oxidative stress and inflammatory cascades induced by radiation. Radiotherapy may cause the development of chronic inflammation and fibrosis, significantly impairing organ function. We hypothesized that bladder irradiation induces an oxidative stress reaction, thereby triggering the redox system and thus initiating an inflammatory and pro-fibrotic response. We aimed to assess whether these changes would be reversed by hyperbaric oxygen using an animal model for radiation cystitis. Our study show that hyperbaric oxygen therapy may reverse oxidative stress and pro-inflammatory factors induced by radiation. [Display omitted] •Bladder irradiation induces an oxidative stress reaction.•The oxidative stress initiates an inflammatory and pro-fibrotic response.•Hyperbaric oxygen may reverse oxidative stress induced by radiation.•Hyperbaric oxygen alone did not induce any changes in the factors studied.