Elucidating the role of miR-155 in the development of paralysis consecutive to spinal cord damage caused by thoracic-abdominal aortic aneurysm repair surgery

项目摘要 胸腹主动脉瘤（TAAA）修复手术最可怕、最不可预测的并发症是 脊髓（SC）缺血性损伤引起的截瘫。迫切需要鉴定新的分子， 将补充现有的非药物预防战略。为此，我们制定了 主动脉阻断（ACC）导致中央脊髓水肿发展的TAAA小鼠模型， 灰质损伤和延迟性后肢瘫痪MicroRNA 155（miR-155），一种短的非编码RNA， 负调节许多靶转录物的表达，已经参与病理学， 慢性炎症和癌症。 使用我们的小鼠模型，我们发现miR-155在运动神经元和内皮细胞中的表达增加， 此外，我们已经确定，miR-155基因的消融限制了ACC后SC的细胞。 减少SC灰质损害的范围，降低SC灰质损伤的程度， 瘫痪率降低40%我们进一步发现，在缺血SC中，miR-155直接靶向Mfsd 2a转录物。 Mfsd 2a编码一种转运蛋白，负责为神经元提供必需的omega-3多不饱和脂肪酸。 二十二碳六烯酸（DHA）。Mfsd 2a对于维持血脑屏障的完整性也是至关重要的。 这些数据表明，miR-155可能靶向许多转录本，并具有复合的有害作用。 在神经血管单位的不同隔室中的作用。因此，我们提出两个互补的 分析miR-155在内皮细胞和运动神经元中的特异性作用的方法。一是 分析特异性删除对水肿发展、灰质损害和瘫痪的后果 我们的小鼠ACC模型中内皮细胞或运动神经元中的miR-155。其次，老鼠，特别是 在内皮细胞或运动神经元中过表达miR-155将用于转录组分析， 为了在正常、非缺血性、非缺血性和非缺血性脑损伤中鉴定这两个细胞区室中的miR-155关键靶点， 条件 在这项研究的最后，我们预计已经确定了miR-155在内皮细胞中最关键的靶点 和运动神经元这些数据将有助于设计新的药物，旨在结合正常化的 miR-155及其关键靶转录物在缺血性SC中的表达。 治疗目前正在进行临床试验，我们相信，我们的研究不仅具有巨大的转化潜力， 预防TAAA修复手术后的截瘫，而且还用于治疗由于 中风或SC/脑创伤性损伤，其中发生miR-155的有害作用。

PROJECT SUMMARY The most feared, unpredictable complication of thoracic-abdominal aortic aneurysm (TAAA) repair surgery is paraplegia caused by ischemic injury to the spinal cord (SC). There is urgency to identify new molecules that would complement existent, non-pharmacological preventive strategies. With this aim, we have developed a mouse model of TAAA where aortic cross-clamping (ACC) results in the development of central cord edema, gray matter damage, and delayed hind-limb paralysis. MicroRNA 155 (miR-155), a short non-coding RNA that negatively regulates the expression of a number of target transcripts, has been involved in pathologies such as chronic inflammation and cancer. Using our mouse model, we have found that miR-155 expression increases in motoneurons and endothelial cells of the SC following ACC. In addition, we have established that the ablation of the miR-155 gene limits the development of central cord edema, reduces the extent extend of SC gray matter damage, and decreases the rate of paralysis by 40%. We further found that, in ischemic SC, miR-155 targets Mfsd2a transcripts directly. Mfsd2a encodes a transporter in charge of supplying neurons with the indispensable omega-3 polyunsaturated docosahexaenoic (DHA) acid. Mfsd2a is also critical for the maintenance of the integrity of blood-brain barrier. These data suggest that miR-155 might target a number of transcripts and have compounding deleterious effects in the different compartments of the neurovascular unit. Therefore, we propose two complementary approaches to analyze miR-155 specific effects in endothelial cells and motoneurons. First, we will analyze the consequences on edema development, gray matter damage and paralysis of specifically deleting miR-155 in endothelial cells or motoneurons in our mouse ACC model. Secondly, mice that specifically overexpress miR-155 in either endothelial cells or motoneurons will be used for transcriptome analyses in order to identify miR-155 critical targets in these two cell compartments in normal, non ischemic conditions. At the end of this study, we anticipate to have identified the most critical targets of miR-155 in endothelial cells and motoneurons. These data will help to design new drugs aimed at combining the normalization of the expression of miR-155 and of its critical target transcripts in ischemic SC. Given that microRNA-directed therapies are now on clinical trials, we believe that our study holds great translational potentials not only for the prevention of paraplegia after TAAA repair surgery, but also for the treatment of neuronal ischemia due to stroke or SC/brain traumatic injuries where deleterious effects of miR-155 take place.