Luckey S W, Petersen D R
Molecular Toxicology and Environmental Health Sciences Program, School of Pharmacy, University of Colorado Health Sciences Center, Denver 80262, USA.
Arch Biochem Biophys. 2001 May 1;389(1):77-83. doi: 10.1006/abbi.2001.2307.
Kupffer cells are known to participate in the early events of liver injury involving lipid peroxidation. 4-Hydroxy-2,3-(E)-nonenal (4-HNE), a major aldehydic product of lipid peroxidation, has been shown to modulate numerous cellular systems and is implicated in the pathogenesis of chemically induced liver damage. The purpose of this study was to characterize the metabolic ability of Kupffer cells to detoxify 4-HNE through oxidative (aldehyde dehydrogenase; ALDH), reductive (alcohol dehydrogenase; ADH), and conjugative (glutathione S-transferase; GST) pathways. Aldehyde dehydrogenase and GST activity was observed, while ADH activity was not detectable in isolated Kupffer cells. Additionally, immunoblots demonstrated that Kupffer cells contain ALDH 1 and ALDH 2 isoforms as well as GST A4-4, P1-1, Ya, and Yb. The cytotoxicity of 4-HNE on Kupffer cells was assessed and the TD50 value of 32.5+/-2.2 microM for 4-HNE was determined. HPLC measurement of 4-HNE metabolism using suspensions of Kupffer cells incubated with 25 microLM 4-HNE indicated a loss of 4-HNE over the 30-min time period. Subsequent production of 4-hydroxy-2-nonenoic acid (HNA) suggested the involvement of the ALDH enzyme system and formation of the 4-HNE-glutathione conjugate implicated GST-mediated catalysis. The basal level of glutathione in Kupffer cells (1.33+/-0.3 nmol of glutathione per 10(6) cells) decreased significantly during incubation with 4-HNE concurrent with formation of the 4-HNE-glutathione conjugate. These data demonstrate that oxidative and conjugative pathways are primarily responsible for the metabolism of 4-HNE in Kupffer cells. However, this cell type is characterized by a relatively low capacity to metabolize 4-HNE in comparison to other liver cell types. Collectively, these data suggest that Kupffer cells are potentially vulnerable to the increased concentrations of 4-HNE occurring during oxidative stress.
已知库普弗细胞参与涉及脂质过氧化的肝损伤早期事件。4-羟基-2,3-(E)-壬烯醛（4-HNE）是脂质过氧化的主要醛类产物，已被证明可调节多种细胞系统，并与化学诱导的肝损伤发病机制有关。本研究的目的是通过氧化（醛脱氢酶；ALDH）、还原（醇脱氢酶；ADH）和结合（谷胱甘肽S-转移酶；GST）途径，表征库普弗细胞解毒4-HNE的代谢能力。在分离出的库普弗细胞中观察到醛脱氢酶和GST活性，而未检测到ADH活性。此外，免疫印迹显示库普弗细胞含有ALDH 1和ALDH 2同工型以及GST A4-4、P1-1、Ya和Yb。评估了4-HNE对库普弗细胞的细胞毒性，并确定4-HNE的TD50值为32.5±2.2 microM。使用与25 microM 4-HNE孵育的库普弗细胞悬液进行4-HNE代谢的HPLC测量表明，在30分钟时间段内4-HNE有所减少。随后4-羟基-2-壬烯酸（HNA）的产生表明ALDH酶系统的参与，4-HNE-谷胱甘肽共轭物的形成暗示了GST介导的催化作用。在与4-HNE孵育期间，库普弗细胞中谷胱甘肽的基础水平（每10(6)个细胞1.33±0.3 nmol谷胱甘肽）显著下降，同时形成了4-HNE-谷胱甘肽共轭物。这些数据表明，氧化和结合途径主要负责库普弗细胞中4-HNE的代谢。然而，与其他肝细胞类型相比，这种细胞类型的特点是代谢4-HNE的能力相对较低。总体而言，这些数据表明库普弗细胞可能易受氧化应激期间4-HNE浓度升高的影响。
