Department of Pathophysiology, Chongqing Medical University, Chongqing, China.
Department of Pharmacology, Chongqing Medical University, Chongqing, China.
Biomed Pharmacother. 2020 May;125:110020. doi: 10.1016/j.biopha.2020.110020. Epub 2020 Feb 25.
The excessive generation of reactive oxygen species (ROS) plays crucial roles in the development of acute liver injury. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is responsible for the robust production of ROS under inflammatory circumstance, but the pathological roles of NOX and the pharmacological significance of NOX inhibitor in acute liver injury remains unclear. In the present study, the potential roles of NOX in acute liver injury were investigated in a mouse model with lipopolysaccharide (LPS)/D-galactosamine (D-Gal)-induced acute liver injury. The results indicated that LPS/D-Gal exposure time-dependently increased the level of ROS in liver tissue. Pretreatment with the NOX inhibitor apocynin suppressed LPS/D-Gal induced upregulation of ROS, 8-hydroxy-2-deoxyguanosine (8-OH-dG), protein carbonyl content and thiobarbituric acid reactive substances (TBARS). Pretreatment with apocynin also suppressed LPS/D-Gal-induced elevation of aminotransferase, alleviated histological abnormalities, inhibited the production of pro-inflammatory cytokine tumor necrosis factor α (TNF-α), blocked the activation of caspase cascade, reduced the count of TUNEL-positive cells and prevented LPS/D-Gal-induced mortality. Interestingly, post insult treatment with apocynin also suppressed LPS/D-Gal-induced oxidative stress, hepatocyte apoptosis, liver damage but improved the survival rate. Mechanistically, posttreatment with apocynin prohibited LPS/D-Gal-induced activation of the late stage pro-apoptotic AMP-activated protein kinase (AMPK)/c-Jun N-terminal kinase (JNK) pathway. Post-insult treatment with the antioxidant N-acetylcysteine also resulted in suppressed activation of AMPK/JNK, mitigated apoptosis and alleviated liver injury. These data suggest that NOX-derived ROS might be a crucial late stage detrimental factor in LPS/D-Gal-induced acute liver injury via promoting the activation of the pro-apoptotic AMPK/JNK pathway, and the NOX inhibitor might have important value in the pharmacological intervention of inflammation-base liver damage.
活性氧（ROS）的过度产生在急性肝损伤的发展中起着关键作用。烟酰胺腺嘌呤二核苷酸磷酸氧化酶（NOX）在炎症环境下负责产生大量的 ROS，但 NOX 的病理作用和 NOX 抑制剂在急性肝损伤中的药理意义尚不清楚。在本研究中，通过脂多糖（LPS）/D-半乳糖胺（D-Gal）诱导的急性肝损伤小鼠模型研究了 NOX 在急性肝损伤中的潜在作用。结果表明，LPS/D-Gal 暴露时间依赖性地增加了肝组织中 ROS 的水平。用 NOX 抑制剂 apocynin 预处理可抑制 LPS/D-Gal 诱导的 ROS、8-羟基-2-脱氧鸟苷（8-OH-dG）、蛋白羰基含量和硫代巴比妥酸反应物质（TBARS）的上调。apocynin 预处理还抑制了 LPS/D-Gal 诱导的氨基转移酶升高，减轻了组织学异常，抑制了促炎细胞因子肿瘤坏死因子-α（TNF-α）的产生，阻断了半胱天冬酶级联的激活，减少了 TUNEL 阳性细胞的数量，并防止了 LPS/D-Gal 诱导的死亡率。有趣的是，apocynin 的后期治疗也抑制了 LPS/D-Gal 诱导的氧化应激、肝细胞凋亡和肝损伤，但提高了存活率。机制上，apocynin 后期治疗可抑制 LPS/D-Gal 诱导的晚期促凋亡 AMP 激活蛋白激酶（AMPK）/c-Jun N 端激酶（JNK）途径的激活。后期治疗用抗氧化剂 N-乙酰半胱氨酸也导致 AMPK/JNK 的激活受到抑制，减轻了细胞凋亡并缓解了肝损伤。这些数据表明，NOX 衍生的 ROS 可能通过促进促凋亡 AMPK/JNK 途径的激活成为 LPS/D-Gal 诱导的急性肝损伤中的一个关键晚期有害因素，而 NOX 抑制剂在炎症相关肝损伤的药理干预中可能具有重要价值。
