Olmesartan ameliorates cyclophosphamide-induced hemorrhagic cystitis in rats via Nrf2/HO-1 signaling pathway

Hemorrhagic cystitis (HC) is considered a fatal complication of cyclophosphamide (CP). Down-regulation of Nrf2 and induction of pro-inflammatory mediators are the main pathological factors. Recently, ameliorative potential of the angiotensin II (AII) type-1 (AT1) receptor blocker olmesartan (OLM) on oxidative stress and inflammatory cytokines was reported. The current study aims to investigate the possible protective effect of OLM on CP-induced HC in Wistar rats. The animals were divided into the control group (0.5% W/V carboxymethylcellulose, p.o.); OLM group (20 mg/kg, p.o., for 21 days); CP group (a single dose of 100 mg/kg, i.p.); and the remaining groups that received CP i.p. with oral OLM 5, 10 and 20 mg/kg for 21 days, respectively. The bladder tissue was collected for histopathology, immunohistochemistry, ELISA, Western blot, and oxidative stress assay. The OLM at doses of 10 and 20 mg/kg attenuated increase in TNF-α, IL-6, NF-kB, iNOS, and COX-2 induced by CP. Additionally, it up-regulated the Nrf2/HO-1 pathway, bladder GSH content, and CAT and SOD activities. The data indicated that OLM inhibited ROS-induced NF-kB, which caused inhibition of pro-inflammatory cytokines and activation of the Nrf2/HO-1 pathway. Hence, OLM holds great promise for preventing CP-induced HC.