Identifying protective roles of the heme oxygenase/carbon monoxide pathway in hypoxia-tolerant model systems

确定血红素加氧酶/一氧化碳途径在耐缺氧模型系统中的保护作用

• 批准号: 9395717
• 负责人: MICHAEL TIFT
• 金额: $ 5.69万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9395717
• 关键词: Adolescent; Adult; Adverse effects; Altitude; Andean; Animal Model; Anti-Inflammatory Agents; Anti-inflammatory; Apoptosis; Apoptotic; Bilirubin; Biliverdin reductase; Biliverdine; Biological Models; Blood; Blood specimen; Carbon Monoxide; Cell Line; Chronic; Cytoprotection; Diving; Dose; Down-Regulation; Enzymes; Erythrocytes; Erythropoiesis; Erythropoietin; Erythropoietin Receptor; Event; Excision; Excretory function; Exhalation; Exhibits; Exposure to; Feces; Fellowship; Gases; Gene Expression; Genes; Genetic; Genome; Genomics; Heme; Hemoglobin; Human; Hypoxia; Individual; Inflammation; Inflammatory; Injury; Investigation; Iron; Ischemia; Label; Laboratory Animals; Laboratory Study; Liver; Longevity; Mammals; Measurement; Measures; Mediating; Methods; Mirounga; Modeling; Molecular; Muscle; Oxidative Stress; Oxygen; Oxygenases; Pathologic; Pathology; Pathway interactions; Patients; Peruvian; Pharmacologic Substance; Physiological; Play; Population; Production; Property; Pulmonary Heart Disease; Pulmonary Hypertension; RNA; Regulation; Reticulocytes; Role; Sampling; Sea; Skeletal Muscle; Sleep Apnea Syndromes; Symptoms; System; Testing; Therapeutic; Therapeutic Effect; Tissue Sample; Tissue-Specific Gene Expression; Tissues; Transcript; Up-Regulation; Urine; Vasodilation; Work; experience; genetic variant; heme oxygenase-1; heme oxygenase-2; human subject; improved; inflammatory marker; insight; interdisciplinary approach; interest; oxidation; personalized medicine; prevent; protective effect; reduce symptoms; seal; skeletal; transcriptome; transcriptome sequencing; transcriptomics; treatment duration

Project Summary/Abstract While many see carbon monoxide (CO) as strictly a toxic gas, CO is also produced in the body from the natural breakdown of heme by heme oxygenase enzymes (HO-1 and HO-2). Recent laboratory studies have shown that exposure to moderate levels of CO will elicit potent cytoprotective effects against hypoxic and ischemic events. These properties have led to the investigation of the therapeutic potential of CO. However, the optimal CO levels through which the safest and the most potent therapeutic effect can be achieved is still unknown. Model systems which exhibit increased endogenous CO as a protective strategy, rather than pathological side effect, will provide insight into CO exposure levels that are safe and effective. Our preliminary work has revealed two human populations and one diving mammal, all adapted to chronic hypoxia, that express increased CO production or positive selection involving the HO-2 gene. Our previous work with Tibetan genomes revealed positive selection at the HO-2 locus, suggesting an important role of the HO/CO pathway in high-altitude adaptation. Similarly, our preliminary end-tidal CO measurements in Peruvian natives show that high-altitude natives have increased end-tidal CO compared to low altitude natives. Likewise, my dissertation work has shown that elephant seals are the only mammal known to produce and maintain CO at the same moderate levels recently deemed therapeutic and protective in the human and laboratory animal studies mentioned above. Elephant seals exhibit repeated, voluntary sleep apnea events (~ 10-15 min) when on land, where they are known to regularly experience degrees of hypoxia and tissue ischemia which would elicit detrimental effects in other mammals. Due to this preliminary evidence, I propose that high-altitude natives and elephant seals represent ideal models to improve our understanding on the mechanisms behind the natural upregulation of the HO/CO pathway in alleviating hypoxia-induced injuries. Specifically, this proposal outlines a multidisciplinary approach into the investigation of the cellular and genetic mechanisms behind the natural upregulation of the HO/CO pathway, and explores the associated tissue-specific protective properties. Humans and elephant seals will be sampled during periods of chronic hypoxia and normoxia. The quantity and activity of HO-1, HO-2 and biliverdin reductase (BVR) will be evaluated in the blood (plus skeletal muscle in elephant seals) from all patients. The precursors (hemoglobin and heme) and products (i.e. CO, iron, biliverdin and bilirubin) of HO and BVR activity will be measured in the same blood samples. The removal rates of CO will be determined through end-tidal CO values and the excretion of bilirubin breakdown products (stercobilin and urobilin) will be measured in the feces and urine. The heme store removal will be measured by investigating red blood cell lifespan. To evaluate the genetic regulation of this pathway, transcriptomics on RNA from the blood samples (plus skeletal and liver tissue in elephant seals) taken after hypoxic and normoxic periods will demonstrate the upregulation or downregulation of specific genes in relation to the HO/CO pathway activity and oxygen availability in the two states. Markers of anti-inflammation, anti- apoptosis, anti-proliferation, and anti-oxidation will be measured in blood and tissue samples and will be compared between groups and to gene expression values and the activity of the HO/CO pathway.

项目摘要/摘要 尽管许多人将碳一氧化碳（CO）视为严格的有毒气体，但CO也是从天然中产生的 血红素氧酶酶（HO-1和HO-2）对血红素的分解。最近的实验室研究表明，接触 中等水平的CO将对低氧和缺血事件产生有效的细胞保护作用。这些属性已 为了研究CO的治疗潜力。但是，最安全和最安全的最佳CO水平 可以实现有效的治疗效果仍然未知。表现出增加内源性CO的模型系统作为A 保护策略而不是病理副作用，将提供对安全有效的CO暴露水平的见解。 我们的初步工作揭示了两个人群和一种潜水哺乳动物，均适合慢性缺氧，这是 明示涉及HO-2基因的CO产生或阳性选择。我们以前用藏基因组的工作 揭示了HO-2基因座的阳性选择，这表明HO/CO途径在高空中的重要作用 适应。同样，我们的秘鲁当地人的初步潮汐CO测量表明，高海拔本地人具有 与低海拔本地人相比，末端潮汐CO增加。同样，我的论文工作表明大象密封是 只有哺乳动物已知可以在同一中等水平上生产和维持CO，最近被认为是治疗和保护性的 上面提到的人类和实验室动物研究。大象印章反复出现自愿睡眠呼吸暂停事件（〜 10-15分钟）当在陆地上经常经历低氧和组织缺血程度 在其他哺乳动物中产生不利影响。由于这个初步证据，我提出高海拔本地人和大象 密封代表理想的模型，以提高我们对HO/CO自然上调背后的机制的理解 减轻缺氧引起的伤害的途径。具体而言，该提案概述了对 研究HO/CO途径自然上调背后的细胞和遗传机制，并探索 相关的组织特异性保护特性。在慢性期间，将对人类和大象印章进行采样 缺氧和常氧。 HO-1，HO-2和Biliverdin还原酶（BVR）的数量和活性将在血液中评估 （加上大象印章中的骨骼肌）来自所有患者。前体（血红蛋白和血红素）和产物（即co，铁， HO和BVR活性的双脂蛋白和胆红素）将在相同的血液样本中测量。 CO的去除率将是 通过潮汐CO值和胆红素分解产物的排泄（Stercobilin和Urobilin）确定为 在粪便和尿液中测量。血红素商店的去除将通过研究红细胞寿命来测量。评估 该途径的遗传调节，来自血液样本RNA的转录组学（以及骨骼和肝组织 在缺氧和正常氧时期采取的大象印章）将证明特定的上调或下调 与HO/CO途径活性和氧气可用性相关的基因。抗炎，抗炎的标记 将在血液和组织样本中测量凋亡，抗增殖和抗氧化，并将在之间进行比较 组和基因表达值以及HO/CO途径的活性。