Novel imaging to identify lung mitochondrial injury and predict recovery

描述（由申请人提供）：氧自由基介导的肺损伤可导致肺移植（缺血再灌注；IR）、高氧、坏死性肺炎等情况。评估肺损伤严重程度的唯一非侵入性临床手段（如CT扫描或氧合）是间接的，它们在恢复或恶化过程中很晚才发现损伤。这些损伤的共同点是线粒体功能障碍，尽管线粒体功能障碍与肺组织损伤之间的因果关系或mtROS在促进IR肺损伤中的作用尚不清楚。PI的愿景是建立线粒体功能障碍在IR损伤中的作用，并使用基于线粒体功能紊乱的新型微创技术诊断这些损伤。这些信息将允许基于个性化的实时风险-收益评估来治疗IR肺损伤患者。我们建立了两种啮齿类动物缺血再灌注IR肺损伤模型：一种是实质性但可恢复的损伤，另一种是导致肺坏死的损伤。我们的数据支持这些IR损伤模型和啮齿动物高氧肺损伤中线粒体生物能量的改变。高氧引起的急性肺损伤（ALI）作为第二种模型特别有吸引力，因为它在临床上（与急性呼吸窘迫综合征）常见，并且与中性粒细胞内流有关。我们介绍了两种新的体内非破坏性成像方法来量化线粒体功能，这些方法有可能非常迅速地转移到临床领域。我们假设：i)红外刺激线粒体功能障碍和mtROS增加，这与随后的细胞凋亡和肺细胞存活率降低的机制相关，如生化和组织学检测ii) SPECT/CT和光学成像可以检测体内线粒体能量和细胞凋亡的改变。IR损伤后成像值的一系列变化将与线粒体功能障碍的程度相关，从而与器官损伤有关。我们将通过解决4个重要问题，以4个具体目标来检验这些假设。(1)线粒体功能障碍和mtROS是IR肺损伤的关键决定因素吗？线粒体生物能量学的一系列变化是否与肺损伤程度相关？(2)单光子发射计算机断层扫描/计算机断层扫描（SPECT/CT）是否可以追踪大鼠肺IR损伤的严重程度，使用针对线粒体功能和细胞凋亡的核医学试剂，并在临床用于替代适应症。(3)光学成像检测的线粒体氧化还原率是否与线粒体功能和肺损伤程度的顺序变化相关？(4)损伤的SPECT和光学成像指标是否与高氧引起的ALI功能障碍程度相关？通过我们在体内检测细胞凋亡和氧化还原损伤的新方法，我们准备研究线粒体生物能量改变、肺结构或功能变化的严重程度以及成像方法追踪这些损伤的潜力之间的相关性。有可能将这些模式快速移动到床边，以改善与移植、严重肺炎、高氧暴露或其他疾病相关的氧化性肺损伤患者的预后。

DESCRIPTION (provided by applicant): Oxygen radical-mediated lung injury may result in settings of lung transplant (ischemia reperfusion; IR), hyperoxia, necrotizing pneumonias and other conditions. The only non-invasive, clinical means (e.g. CT scans or oxygenation) to assess the severity of lung injury are indirect, and they detect damage very late in the process of recovery or deterioration. Common to these injuries is mitochondrial dysfunction, though the causal relationship between mitochondrial dysfunction and injury in lung tissue or the role of mtROS in promoting IR lung injury is not known. The PI's vision is to establish the role of mitochondrial dysfunction in IR injuries and diagnose these injuries using novel minimally invasive techniques based upon deranged mitochondrial function. This information will permit treatment of patients with IR lung injury based upon individualized risk-benefit assessments in real time. We have developed two rodent ischemia reperfusion IR lung injury models: one with substantial but recoverable injury and a second which results in necrotic lung. Our data support altered mitochondrial bioenergetics in these IR injury models and in rodent hyperoxic lung injury. Acute lung injury (ALI) from hyperoxia is particularly attractive as a second model because it is commonly encountered clinically (with Acute Respiratory Distress Syndrome) and it is associated with neutrophilic influx. We introduce two novel in vivo, non-destructive imaging methods for quantifying mitochondrial function that have potential to be transferred very rapidly to the clinical field. We hypothesize that: i) IR stimulates mitochondrial dysfunction and increased mtROS which are mechanistically linked to subsequent apoptosis and decreased lung cell survival as detected biochemically and histologically ii) SPECT/CT and optical imaging can detect altered mitochondrial energetics and apoptosis in vivo. Serial changes in imaging values after IR injury will correlate to the extent of mitochondrial dysfunction and hence organ injury. We will test these hypotheses with four specific aims by addressing 4 important questions. (1) Are mitochondrial dysfunction and mtROS critical determinants of IR lung injury? Do serial changes in mitochondrial bioenergetics correlate with the extent of lung injury? (2) Can we track the severity of rat lung IR injury with single photon emission computed tomography/computed tomography (SPECT/CT) using nuclear medicine agents which target mitochondrial function and apoptosis and are in clinical use for alternative indications. (3) Do mitochondrial redox ratios detected in vivo by optical imaging correlate to sequential changes in mitochondrial function and extent of lung injury? (4) Do SPECT and optical imaging indices of injury correlate to extent of dysfunction in ALI produced by hyperoxia? With our novel means to detect apoptosis and redox injury in vivo, we are poised to examine correlations between altered mitochondrial bioenergetics, severity of changes to lung structure or function and the potential of imaging methods to track these injuries. There is potential to move these modalities quickly to the bedside to improve the outcome for patients with oxidoreductive lung damage related to transplantation, severe pneumonias, hyperoxic exposure or other disorders.