Role of Nrf2 signaling pathway in attenuation of ischemia injury by hydrogen-rich University of Wisconsin solution during cold storage of rat donor kidneys

Abstract

Objective To evaluate the role of nuclear factor erythroid 2-related factor 2(Nrf2)signaling pathway in attenuation of ischemia injury by hydrogen-rich University of Wisconsin(HRUW)solution during cold storage of rat donor kidneys. Methods Forty healthy adult male Wistar rats, weighing 200-250 g, were divided into 4 groups(n=10 each)using a random number table: control group(group C), University of Wisconsin(UW)solution group(group UW), HRUW solution group(group HRUW)and Nrf2 inhibitor all-trans retinoic acid(ATRA)group(group ATRA). ATRA 7 mg/kg was intraperitioneally injected once a day for 2 consecutive days, kidneys were isolated and underwent cold storage at 8 h after the last administration, and kidneys were stored in HRUW solution for 48 h at 4 ℃ in group ATRA.In UW and HRUW groups, the equal volume of normal saline was intraperitioneally injected instead, and isolated kidneys were stored in UW solution and HRUW solution for 48 h at 4 °C, respectively.Kidney specimens were obtained for microscopic examination and for determination of tumor necrosis factor-alpha(TNF-α), interleukin-1beta(IL-1β), high-mobility group box 1 protein(HMGB1), IL-10 and 8-iso-prostaglandin F2α(8-iso-PGF2α)contents(by enzyme-linked immunosorbent assay), superoxide dismutase(SOD)and catalase(CAT)activities(using spectrophotometry), and expression of Nrf2, heme oxygenase-1(HO-1), Bcl-2, Bax and caspase-3 in renal tissues(by using Western blot). The damage to the renal tubules was scored. Results Compared with group C, renal tubular damage scores were significantly increased, TNF-α, IL-1β, HMGB1 and 8-iso-PGF2α contents were increased, IL-10 contents were decreased, the expression of Nrf2 and HO-1 was up-regulated, SOD and CAT activities were decreased, the expression of Bcl-2 was down-regulated, and the expression of Bax and caspase-3 was up-regulated in group UW(P 0.05). Compared with group HRUW, renal tubular damage scores were significantly increased, TNF-α, IL-1β, HMGB1 and 8-iso-PGF2α contents were increased, IL-10 contents were decreased, the expression of HO-1 and Bcl-2 was down-regulated, SOD and CAT activities were decreased, and the expression of Bax and caspase-3 was up-regulated in group ATRA. Conclusion HRUW solution reduces inflammatory responses, oxidative damage and cell apoptosis during cold storage of rat donor kidneys, and the mechanism by which HRUW solution attenuates ischemia injury is related to activation of Nrf2 signaling pathway. Key words: Hydrogen; NF-E2 related factor 2; Kidney transplantation; Cryopreservation; Cold ischemia