Chronic ethanol feeding increases activation of NADPH oxidase by lipopolysaccharide in rat Kupffer cells:: role of increased reactive oxygen in LPS-stimulated ERK1/2 activation and TNF-α production
Chronic ethanol feeding increases activation of NADPH oxidase by lipopolysaccharide in rat Kupffer cells:: role of increased reactive oxygen in LPS-stimulated ERK1/2 activation and TNF-α production
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DOI：
10.1189/jlb.1005613
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发表时间：
2006-06-01
影响因子：
5.5
通讯作者：
Nagy, Laura E.
中科院分区：
文献类型：
--
作者：
Thakur, Varsha;Pritchard, Michele T.;Nagy, Laura E.
活性氧（ROS）参与慢性乙醇性肝损伤的发生发展。虽然ROS调节许多信号转导途径的活性，但在乙醇暴露期间ROS的分子靶点还不清楚。在这里，我们调查是否特定的ROS敏感的信号转导通路有助于增加肿瘤坏死因子α（TNF-α）的生产库普弗细胞慢性乙醇喂养大鼠后。脂多糖（LPS）迅速增加活性氧的生产，测量二氢罗丹明荧光，在库普弗细胞从乙醇和对喂养的大鼠，和活性氧的生产是2.5倍，乙醇喂养相比，对喂养。预处理与二苯基碘（DPI），抑制还原型烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶，正常的活性氧产生的库普弗细胞从乙醇喂养的大鼠。LPS迅速增加Rac 1-鸟苷三磷酸酶（GTdR）的活性和P67（phox）易位到质膜在Kupffer细胞从对喂大鼠。在乙醇喂养后，Rac 1-GTdR活性在基线时已经比配对喂养增加，并且在LPS刺激后比配对喂养保持升高。此外，LPS刺激的p67（phox）易位到质膜后，慢性乙醇喂养增强。LPS刺激的细胞外信号调节激酶（ERK）1/2和p38磷酸化，ROS调节的两个信号通路，增加了两倍，在库普弗细胞从乙醇喂养的大鼠相比，对喂养的控制。然而，只有LPS刺激的ERKI/2磷酸化被DPI抑制，DPI也减少了来自成对和乙醇喂养大鼠的Kupffer细胞中LPS刺激的TNF-α的产生。这些结果表明，慢性乙醇喂养增加了库普弗细胞中LPS刺激的NADPH氧化酶依赖性ROS的产生。此外，ERK 1/2是库普弗细胞中NADPH氧化酶衍生的ROS的重要靶点，有助于增强慢性乙醇喂养后库普弗细胞的LPS刺激的TNF-α产生。
Reactive oxygen species (ROS) contribute to the development of chronic ethanol-induced liver injury. Although ROS modulate the activity of many signal transduction pathways, the molecular targets of ROS during ethanol exposure are not well understood. Here, we investigated whether specific ROS-sensitive signal transduction pathways contribute to increased tumor necrosis factor alpha (TNF-alpha) production by Kupffer cells after chronic ethanol feeding to rats. Lipopolysaccharide (LPS) rapidly increased ROS production, measured by dihydrorhodamine fluorescence, in Kupffer cells from ethanol- and pair-fed rats, and ROS production was 2.5-fold greater in ethanol-fed compared with pair-fed. Pretreatment with diphenyleneiodonium (DPI), which inhibits reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, normalized ROS production in Kupffer cells from ethanol-fed rats. LPS rapidly increased Rac1-guanosinetriphosphatase (GTPase) activity and P67(phox) translocation to the plasma membrane in Kupffer cells from pair-fed rats. After ethanol feeding, Rac1-GTPase activity was already increased over pair-fed at baseline and remained elevated over pair-fed after LPS stimulation. Further, LPS-stimulated p67(phox) translocation to the Plasma membrane was enhanced after chronic ethanol feeding. LPS-stimulated extracellular signal-regulated kinase (ERK)1/2 and p38 phosphorylation, two signaling pathways regulated by ROS, were increased twofold in Kupffer cells from ethanol-fed rats compared with pair-fed controls. However, only LPS-stimulated ERKI/2 phosphorylation was inhibited by DPI, which also reduced LPS-stimulated TNF-alpha production in Kupffer cells from pair- and ethanol-fed rats. These results demonstrate that chronic ethanol feeding increases LPS-stimulated NADPH oxidase-dependent production of ROS in Kupffer cells. Further, ERK1/2 is an important target of NADPH oxidase-derived ROS in Kupffer cells, contributing to enhanced LPS-stimulated TNF-alpha production by Kupffer cells after chronic ethanol feeding.