Intracellular Iron Accumulation in Cystic Fibrosis

囊性纤维化中的细胞内铁积累

• 批准号: 7133876
• 负责人: Jennifer L. Turi
• 金额: $ 12.56万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7133876
• 关键词: biological transport; cystic fibrosis; cytotoxicity; ferritin; free radical oxygen; gene expression; genetically modified animals; human tissue; inflammation; interleukin 1; intracellular; iron metabolism; iron poisoning; laboratory mouse; laboratory rat; lipopolysaccharides; macrophage; oxidative stress; pathologic process; respiratory epithelium; sodium channel; tissue /cell culture; transfection /expression vector; transport proteins; tumor necrosis factor alpha

DESCRIPTION (provided by applicant): This proposal will enable the principal investigator to develop into an independent physician-scientist and gain new expertise in oxidative biology, gene regulation, and cystic fibrosis (CF). CF is a common, highly morbid, and ultimately fatal disease characterized by persistent pseudomonas lung infections and severe airways obstruction. It is also associated with markedly elevated concentrations of iron in the airway that may contribute to CF morbidity by generating oxidant injury, and supplying pseudomonas with an essential nutrient to exacerbate infection. Airway epithelial cells protect against these effects by transporting iron via natural resistance-associated macrophage protein 2 (Nramp-2) into the cell where it is sequestered by ferritin. To prevent intracellular accumulation, iron is mobilized from lung cells via metal transport protein 1 (MTP1). We present data to support two potential mechanisms of intracellular iron accumulation in CF. First, inflammation appears to increase Nramp-2 expression, decrease MTP1 expression, and elevate intracellular iron concentration. Second, basal expression of Nramp-2 and MTP1 appears elevated in unstimulated CF cells. This may be due to increased Na+ absorption via the epithelial channel (ENaC), that is typical in CF, given our data showing iron transport requires concurrent Na+ transport and ferritin is increased in airways of mice over-expressing ENaC. We will test the hypotheses that: 1) Inflammation increases Nramp-2 expression and decreases MTP1 expression in airway epithelial cells resulting in intracellular iron overload; 2) Increased intracellular iron, in the presence of inflammation, causes ROS generation and oxidant injury; and 3) In addition to and independently of inflammation, Nramp-2 and MTP1 expression are mediated by increased expression of ENaC in CF epithelial cells. Three Specific Aims will be tested: 1) Evaluate the extent to which LPS and proinflammatory cytokines IL-1B and TNF-a regulate iron transport proteins and increase cellular iron concentration in airway epithelial cells; 2) Evaluate whether elevated intracellular iron during inflammation stimulates ROS production and generates oxidative injury; 3) Investigate the role of increased ENaC expression in the regulation of Nramp-2 and MTP1 expression in CF in the presence and absence of inflammatory stimuli. These data will provide a scientific foundation to understand mechanisms of iron overload in CF and its role in the vulnerability of the airway to oxidative damage and cytotoxicity. (End of Abstract)

描述（由申请人提供）： 该提案将使主要研究者能够发展成为一名独立的医师科学家，并获得氧化生物学、基因调控和囊性纤维化（CF）方面的新专业知识。 CF 是一种常见、高发病率并最终致命的疾病，其特征是持续性假单胞菌肺部感染和严重气道阻塞。它还与气道中铁浓度显着升高有关，可能通过产生氧化损伤并为假单胞菌提供必需的营养物质来加剧感染，从而导致 CF 发病。气道上皮细胞通过天然抵抗相关巨噬细胞蛋白 2 (Nramp-2) 将铁转运到细胞中，并被铁蛋白隔离，从而防止这些影响。为了防止细胞内积累，铁通过金属转运蛋白 1 (MTP1) 从肺细胞中动员。我们提供的数据支持 CF 中细胞内铁积累的两种潜在机制。首先，炎症似乎会增加 Nramp-2 表达，降低 MTP1 表达，并升高细胞内铁浓度。其次，Nramp-2 和 MTP1 的基础表达在未刺激的 CF 细胞中似乎升高。这可能是由于通过上皮通道 (ENaC) 的 Na+ 吸收增加，这在 CF 中很常见，因为我们的数据显示铁转运需要同时进行 Na+ 转运，并且过度表达 ENaC 的小鼠气道中铁蛋白增加。我们将检验以下假设： 1) 炎症增加气道上皮细胞中 Nramp-2 的表达并降低 MTP1 的表达，导致细胞内铁超载； 2）细胞内铁增加，在炎症存在的情况下，导致ROS生成和氧化损伤； 3) 除了炎症之外且与炎症无关，Nramp-2 和 MTP1 表达是由 CF 上皮细胞中 ENaC 表达增加介导的。将测试三个具体目标： 1) 评估 LPS 和促炎细胞因子 IL-1B 和 TNF-a 调节铁转运蛋白并增加气道上皮细胞中细胞铁浓度的程度； 2）评估炎症过程中细胞内铁升高是否刺激ROS产生并产生氧化损伤； 3)研究在存在和不存在炎症刺激的情况下ENaC表达增加在调节CF中Nramp-2和MTP1表达中的作用。这些数据将为了解 CF 中铁超载的机制及其在气道易受氧化损伤和细胞毒性影响中的作用提供科学基础。 （摘要完）