HEME OXYGENASE AND NEONATAL HYPEROXIC INJURY

血红素加氧酶和新生儿高氧损伤

• 批准号: 6476785
• 负责人: PHYLLIS A. DENNERY
• 金额: $ 31.71万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-12-07 至 2003-07-10
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6476785
• 关键词: animal tissue; antioxidants; antisense nucleic acid; atomic absorption spectrometry; autoradiography; cytoprotection; densitometry; enzyme activity; fluorescence spectrometry; fluorescent dye /probe; gene expression; genetically modified animals; glutathione; heme oxygenase; hemoprotein; hyperoxia; isozymes; laboratory mouse; newborn animals; oxidative stress; particle counter; peroxidation; respiratory gas analyzer; tissue /cell culture

Oxygen toxicity may cause deleterious effects in the lung and may account for some of the changes of chronic lung disease of the newborn. The inducible isoenzyme of heme oxygenase (HO-1) is known to be upregulated in hyperoxia. Furthermore, moderate levels of HO-1 expression are associated with increased protection against oxygen toxicity in vitro. However, the effect of higher HO-1 expression has not been examined clearly and preliminary studies suggest an optimal range of HO-1 over-expression in antioxidant defenses in vitro. Nothing is known about the effect of over-expression or elimination of HO-2, the constitutive isoenzyme in vitro, but recent observations suggest that HO-2, unlike HO-1, may additionally serve to sequester heme at two binding sites thereby suggesting that the two isoenzymes serve in differing roles in oxygen toxicity. As to the in vivo role of both HO isoenzymes, it has recently been shown that absence of HO is detrimental to adult mutant mice. Aging null mutants lacking HO-1 had increased markers of oxidative injury and younger HO-2 null mutants had increased susceptibility to oxygen toxicity. Since it is known that both HO-1 and H0-2 are expressed at higher levels in the lungs of newly born animals compared to adults, we speculate that HO is even more relevant to neonatal antioxidant defense in vivo. In this proposal, in order to further define the role of HO in antioxidant defense, we plan to precisely modulate HO expression in cultured fetal pulmonary cells using a tetracycline regulated promoter to define whether there is an optimal range HO expression in vitro. We will also use neonatal mutant mice that lack HO-1 or HO-2 and transgenic mice which over-express HO-1 or HO-2 to determine if HO expression is associated with protection against hyperoxia in vivo. Lastly, we will determine whether differences exist in the antioxidant function of HO-1 and HO-2 in vitro and in vivo. Prior to considering modulation of HO as a therapeutic intervention, it will be necessary to clarify whether HO is protective against hyperoxic injury in vivo and to understand what manner and magnitude of HO expression is most beneficial to cells. A better understanding of the role of lung HO in the neonate will allow us to identify strategies to enhance this endogenous neonatal antioxidant defense.

氧毒性可能会在肺中引起有害作用，并且可能 解释了新生儿慢性肺部疾病的某些变化。 血红素加氧酶（HO-1）的诱导同工酶已知为 在高氧中上调。 此外，HO-1的水平中等 表达与对氧气的保护增加有关 体外毒性。 但是，较高的HO-1表达的影响具有 未清楚检查，初步研究表明最佳 HO-1在体外抗氧化剂防御中的过表达范围。 没有什么 已经知道过表达或消除HO-2的影响 体外组成型同工酶，但最近的观察结果表明 HO-2与HO-1不同，可以另外用来隔离两个 结合位点，因此表明两个同工酶在 在氧毒性中的作用不同。 至于两个ho的体内角色 同工酶，最近已证明缺乏HO是有害的 到成年突变小鼠。 缺乏HO-1的衰老零突变体增加了 氧化损伤和年轻HO-2无效突变体的标记增加了 对氧毒性的敏感性。 由于知道HO-1和 H0-2在新生动物的肺中以较高的水平表示 与成年人相比，我们推测HO与 新生儿抗氧化剂防御体内。 在此提案中，为了 进一步定义了HO在抗氧化防御中的作用，我们计划 精确调节培养的胎儿肺细胞中HO表达 四环素调节的启动子，以定义是否有最佳 体外范围HO表达。 我们还将使用新生儿突变小鼠 缺乏过表达HO-1或的HO-1或HO-2和转基因小鼠 HO-2确定HO表达是否与保护有关 体内高氧。 最后，我们将确定是否存在差异 在体外和体内HO-1和HO-2的抗氧化功能中。事先的 要考虑调节HO作为治疗性干预措施，它将 有必要阐明HO是否可以保护过度氧气 体内受伤并了解HO的方式和大小 表达对细胞最有益。 更好地理解 肺Ho在新生儿中的作用将使我们能够确定策略 增强这种内源性新生儿抗氧化剂防御。