- 作者：Bibo Ke ; Xiu-Da Shen ; Yu Zhang ; Haofeng Ji ; Feng Gao ; Shi Yue ; Naoko Kamo ; Yuan Zhai ; Masayuki Yamamoto ; Ronald W. Busuttil ; Jerzy W. Kupiec-Weglinski
- 关键词：ARE ; anti-oxidant response element ; HIF-1 ; hypoxia inducible factor-1 ; HKO ; hepatocyte knockout ; HO-1 ; heme-oxygenase-1 ; HRE ; hypoxia response element ; H2O2 ; hydrogen peroxide ; IRI ; ischemia/reperfusion injury ; Keap1 ; Kelch-like ECH-associated protein 1 ; LDH ; lactate dehydrogenase ; Nrf2 ; nuclear factor erythroid 2-related factor 2 ; OLT ; orthotopic liver transplantation ; PI3K ; phosphoinositide 3-kinase ; sALT ; serum alanine aminotransferase ; Trx1 ; thioredoxin 1 ; TUNEL ; terminal deoxyribonucleotidy
- 刊名：Journal of Hepatology
- 出版年：December, 2013
- 年：2013
- 卷：59
- 期：6
- 页码：1200-1207
- 全文大小：1465 K
Background & Aims
The Keap1-Nrf2 signaling pathway regulates host cell defense responses against oxidative stress and maintains the cellular redox balance.Methods
We investigated the function/molecular mechanisms by which Keap1-Nrf2 complex may influence liver ischemia/reperfusion injury (IRI) in a mouse model of hepatic cold storage (20 h at 4 掳C) followed by orthotopic liver transplantation (OLT).
Results
The Keap1 hepatocyte-specific knockout (HKO) in the donor liver ameliorated post-transplant IRI, evidenced by improved hepatocellular function and OLT outcomes (Keap1 HKO鈫?em>Keap1 HKO; 100% survival), as compared with controls (WT鈫扺T; 50% survival; p <0.01). By contrast, donor liver Nrf2 deficiency exacerbated IRI in transplant recipients (Nrf2 KO鈫?em>Nrf2 KO; 40% survival). Ablation of Keap1 signaling reduced macrophage/neutrophil trafficking, pro-inflammatory cytokine programs, and hepatocellular necrosis/apoptosis, while simultaneously promoting anti-apoptotic functions in OLTs. At the molecular level, Keap1 HKO increased Nrf2 levels, stimulated Akt phosphorylation, and enhanced expression of anti-oxidant Trx1, HIF-1伪, and HO-1. Pretreatment of liver donors with PI3K inhibitor () disrupted Akt/HIF-1A signaling and recreated hepatocellular damage in otherwise IR-resistant Keap1 HKO transplants. In parallel in vitro studies, hydrogen peroxide-stressed Keap1-deficient hepatocytes were characterized by enhanced expression of Nrf2, Trx1, and Akt phosphorylation, in association with decreased release of lactate dehydrogenase (LDH) in cell culture supernatants.
Conclusions
Keap1-Nrf2 complex prevents oxidative injury in IR-stressed OLTs through Keap1 signaling, which negatively regulates Nrf2 pathway. Activation of Nrf2 induces Trx1 and promotes PI3K/Akt, crucial for HIF-1伪 activity. HIF-1伪-mediated overexpression of HO-1/Cyclin D1 facilitates cytoprotection by limiting hepatic inflammatory responses, and hepatocellular necrosis/apoptosis in a PI3K-dependent manner.