Pediatric Critical Care, Department of Pediatrics, University of Colorado at Denver, Aurora, CO 80045, USA.
Free Radic Biol Med. 2010 Dec 15;49(12):2032-9. doi: 10.1016/j.freeradbiomed.2010.09.028. Epub 2010 Oct 4.
Delivery of recombinant superoxide dismutase to the lung is limited by its short half-life and poor tissue penetration. We hypothesized that a chimeric protein, SOD2/3, containing the enzymatic domain of manganese superoxide dismutase (SOD2) and the heparan-binding domain of extracellular superoxide dismutase (SOD3), would allow for the delivery of more sustained lung and pulmonary vascular antioxidant activity compared to SOD2. We administered SOD2/3 to rats by intratracheal (i.t.), intraperitoneal (i.p.), or intravenous (i.v.) routes and evaluated the presence, localization, and activity of lung SOD2/3 1 day later using Western blot, immunohistochemistry, and SOD activity gels. The effect of i.t. SOD2/3 on the pulmonary and systemic circulation was studied in vivo in chronically catheterized rats exposed to acute hypoxia. Active SOD2/3 was detected in lung 1 day after i.t. administration but not detected after i.p. or i.v. SOD2/3 administration or i.t. SOD2. The physiologic response to acute hypoxia, vasoconstriction in the pulmonary circulation and vasodilation in the systemic circulation, was enhanced in rats treated 1 day earlier with i.t. SOD2/3. These findings indicate that i.t. administration of SOD2/3 effectively delivers sustained enzyme activity to the lung as well as pulmonary circulation and has a longer tissue half-life compared to native SOD2. Further testing in models of chronic lung or pulmonary vascular diseases mediated by excess superoxide should consider the longer tissue half-life of SOD2/3 as well as its potential systemic vascular effects.
向肺部输送重组超氧化物歧化酶受到其半衰期短和组织穿透性差的限制。我们假设，一种嵌合蛋白 SOD2/3，包含锰超氧化物歧化酶（SOD2）的酶结构域和细胞外超氧化物歧化酶（SOD3）的肝素结合结构域，将允许与 SOD2 相比，更持续地向肺部和肺血管输送抗氧化活性。我们通过气管内（i.t.）、腹腔内（i.p.）或静脉内（i.v.）途径向大鼠给予 SOD2/3，并在 1 天后使用 Western blot、免疫组织化学和 SOD 活性凝胶评估肺 SOD2/3 的存在、定位和活性。通过在暴露于急性缺氧的慢性导管化大鼠中体内研究 i.t. SOD2/3 对肺和全身循环的影响。在 i.t.给予后 1 天可检测到活性 SOD2/3，但在 i.p.或 i.v.给予 SOD2/3 或 i.t. SOD2 后未检测到。在接受 i.t. SOD2/3 治疗 1 天的大鼠中，急性缺氧引起的生理反应（肺循环中的血管收缩和体循环中的血管扩张）增强。这些发现表明，与天然 SOD2 相比，i.t.给予 SOD2/3 可有效地将持续的酶活性输送到肺部以及肺循环中，并且具有更长的组织半衰期。在由过量超氧化物介导的慢性肺部或肺血管疾病模型中进一步测试时，应考虑 SOD2/3 的较长组织半衰期及其潜在的全身血管效应。
