Chang Cheow K, LoCicero Joseph
Department of Surgery, Finch University of Health Sciences/The Chicago Medical School at Mount Sinai Hospital Medical Center, Chicago, Illinois, USA.
Ann Thorac Surg. 2004 Apr;77(4):1222-7; discussion 1227. doi: 10.1016/j.athoracsur.2003.09.128.
Transcriptional regulation is a major determinant of interleukin-1beta (IL-1beta) protein synthesis. Nuclear factor kappaB (NF-kappaB) plays a central role in the regulation of IL-1beta and subsequent IL-1beta-dependent inflammatory processes. Previously, we observed in a murine endotoxic stress model a progressive increase with age in the amount of IL-1beta mRNA. We test the aging pulmonary response of NF-kappaB and NF-kappaB-dependent genes, IL-1beta, and inducible nitric oxide synthase (iNOS) in the same model.
Young (2-month-old) and senescent (25-month-old) mice were given 0.5 mg/kg lipopolysaccharide (LPS) intraperitoneally. Lung and blood samples were harvested after 4 hours. IL-1beta production in blood samples and the expression levels of protein and mRNA of IL-1beta and iNOS in lung tissues were measured. NF-kappaB binding activity in lung tissues was also determined.
LPS induced higher levels of IL-1beta in the sera and lungs of senescent mice over young mice. Northern and Western blot analyses showed that mRNA and protein signals of IL-1beta and iNOS were significantly higher in old lungs than in young lungs. Electrophoretic mobility shift assay also showed that NF-kappaB activation was significantly higher in the older animals.
Our results suggest that elevated activation of NF-kappaB, at least in part, contributes to the dysregulated expression of IL-1beta and iNOS in the lungs of senescent animals. Thus increased expression of proinflammatory cytokines and inflammatory responsive genes in the lung may play a role in the increased susceptibility in aging animals to endotoxic stress.
转录调控是白细胞介素-1β（IL-1β）蛋白合成的主要决定因素。核因子κB（NF-κB）在IL-1β的调控以及随后依赖IL-1β的炎症过程中起核心作用。此前，我们在小鼠内毒素应激模型中观察到，IL-1β mRNA的量随年龄增长而逐渐增加。我们在同一模型中测试了衰老肺脏对NF-κB及依赖NF-κB的基因、IL-1β和诱导型一氧化氮合酶（iNOS）的反应。
给年轻（2个月大）和衰老（25个月大）的小鼠腹腔注射0.5 mg/kg脂多糖（LPS）。4小时后采集肺和血液样本。检测血液样本中IL-1β的产生以及肺组织中IL-1β和iNOS的蛋白和mRNA表达水平。还测定了肺组织中NF-κB的结合活性。
与年轻小鼠相比，LPS诱导衰老小鼠血清和肺中IL-1β水平更高。Northern和Western印迹分析表明，老年肺中IL-1β和iNOS的mRNA和蛋白信号明显高于年轻肺。电泳迁移率变动分析也表明，老年动物中NF-κB的激活明显更高。
我们的结果表明，NF-κB激活升高至少部分导致了衰老动物肺中IL-1β和iNOS的表达失调。因此，肺中促炎细胞因子和炎症反应基因表达增加可能在衰老动物对内毒素应激易感性增加中起作用。
