Renal salvage via Nrf2-dependent antioxidative/anti-inflammatory enzymes

Zhu, Hong

Abstract

Renal ischemia-reperfusion injury is an important clinical problem, for which currently there is no cure. Substantial evidence supports a causal role for oxidative stress and inflammation in the pathogenesis of renal ischemia-reperfusion. Accordingly, exogenous antioxidative/anti-inflammatory compounds have been used for protective or therapeutic intervention of renal ischemia-reperfusion injury. We propose an innovative strategy for protective/therapeutic intervention of renal ischemia-reperfusion injury through chemoprotectant-mediated coordinated upregulation of endogenous antioxidative/anti-inflammatory enzymes in kidneys. The coordinated actions of a spectrum of cellular antioxidative/anti-inflammatory enzymes are essential for efficient detoxification of reactive oxygen species (ROS) and other reactive species that participate in the pathogenesis of renal ischemia-reperfusion injury. The long-term objective of this project is to develop rational protective/therapeutic strategies to prevent, arrest, or even reverse the oxidative and inflammatory process underlying renal ischemia-reperfusion. Such strategies rely on a profound understanding of the chemical inducibility of cellular antioxidative/anti-inflammatory enzymes, and the underlying molecular mechanisms in kidneys. Recently, NF-E2-related factor 2 (Nrf2) has been found to be a critical transcription factor in regulation of antioxidative/anti-inflammatory gene expression in animal tissues, including liver and lung. However, the role of Nrf2 signaling in regulating expression of antioxidative/anti-inflammatory enzymes in kidneys, as well as in protecting against renal ischemia-reperfusion injury has not been investigated. The hypotheses we are investigating in this R15 proposal are that Nrf2 signaling is crucial in regulating both constitutive and inducible expression of a spectrum of key antioxidative/anti-inflammatory enzymes in kidneys, and that the coordinated upregulation of the Nrf2-dependent antioxidative/anti-inflammatory defenses provides highly effective protection against renal ischemia-reperfusion injury in animals. Accordingly, this R15 proposal will characterize the regulatory role of Nrf2 in constitutive and inducible expression of endogenous antioxidative/anti-inflammatory enzymes in kidney tissue using Nrf2-null and wild-type mice. The potent chemoprotective agent, 3H-1,2-dithiole-3-thione (D3T) will be used to investigate the role of Nrf2 in regulating inducible expression of renal antioxidative/anti-inflammatory enzymes. Pharmacokinetic studies will be performed to determine the distribution of D3T to kidneys. Lastly, this R15 proposal will investigate the protective role of Nrf2-regulated constitutively expressed as well as D3T-inducible antioxidative enzymes in the pathophysiological processes of in vivo renal ischemia-reperfusion injury as well as in vitro hypoxia/reoxygenation injury in cultured proximal tubular cells. Fulfillment of the above aims will lay a strong basis for future comprehensive investigation on chemoprotection against renal ischemia-reperfusion injury as well as other kidney disorders involving oxidative stress and inflammation.

Public Health Relevance

Renal ischemia-reperfusion injury is a major clinical problem, for which there is no effective approach to intervention. Substantial evidence supports a causal role for reactive oxygen species (ROS) and dysregulated inflammation in the pathogenesis of renal ischemia-reperfusion injury. This project is to investigate the protective role of coordinated activation of a series of endogenous renal antioxidative/anti-inflammatory enzymes in renal ischemia-reperfusion injury. Completion of this project will contribute to the development of more effective mechanistically-based protective and/or therapeutic strategies for management of renal ischemia-reperfusion injury as well as other kidney disorders that involve an oxidative/inflammatory mechanism.