HO-1介导烧伤后急性肾损伤内源性保护机制的研究

Acute kidney injury (AKI) is a common and devastating complication in severely burned patients, which may lead to a poor prognosis without appropriate treatments. The previous studies indicate there is an inner defense system against the development of AKI post burn, however, it is unclear about the detailed mechanism and targets of regulation. In our recent study, we found both molecular hydrogen and astaxanthin could protect against the progressive renal dysfunction and histological injury in severely burned rats by ameliorating oxidative stress, inflammation and mitochondria-related apoptosis in renal tissue. In addition, there was a time-relative up-regulation of HO-1 paralleling to the development of AKI post burn, while a down-regulation of downstream HMGB-1or NF-κB p65 (as inflammation or apoptosis relative signals) expression was also observed. Furthermore, we observed an increased distribution and expression of HO-1 secondary to protectants application, combined with a relief of AKI post burn. Therefore, considering the reported nephroprotective effect of HO-1 in diverse kidney injuries or diseases, we infer the key role of HO-1 in the inner protection against AKI after burn insult, and its mechanism of action is still not understood. In the present research project, we intend to explore details of HO-1 about distribution, protein-expression, mechanism of action and upstream regulatory signaling pathway, utilizing protein chip, shRNA, knockout animals and other methods. Finally, we would like to make clear and demonstrate the role and regulatory mechanism of HO-1 in inner protection, which may provide a novel theoretical basis for the diagnosis and treatment of burn induced AKI.

烧伤后急性肾损伤（AKI）是重度烧伤患者常见并发症，处理不当会严重影响预后。研究表明机体存在对烧伤后AKI的内源性保护机制，但机制尚未明确。我们近期研究利用分子氢及虾青素干预烧伤后肾组织中氧化应激、炎症反应及线粒体相关凋亡，可有效缓解烧伤后肾组织结构破坏及功能减退；且肾组织内HO-1的分布表达随时间明显上调，并伴随部分炎症、凋亡调节蛋白（HMGB-1、NF-κB p65等）表达降低；而药物有效缓解烧伤后急性肾损伤的过程中伴随HO-1的分布表达进一步上调。结合已知HO-1的肾保护作用，我们推测HO-1可能是烧伤后急性肾损伤内源性保护作用的关键蛋白，其具体作用机制亟待阐明。本项目拟利用蛋白芯片、shRNA、基因敲除等方法深入研究HO-1在烧伤后肾组织中的分布表达规律、作用机制及上游调控信号通路，以明确HO-1在内源性保护中的具体作用及分子机制，为烧伤后AKI的的诊治提供新的理论依据。

背景：烧伤患者尤其是重度烧伤患者除了创面本身，在早期治疗中还必须面对各种脏器损伤的风险。肾脏作为易受缺血、氧化应激刺激损伤的器官，在严重创伤（包括烧伤）、重大手术后易出现急性肾损伤。烧伤后早期急性肾损伤如果没有及时治疗，可能持续进展为不可逆的慢性肾脏损伤，诱发器官衰竭。重度烧伤患者中约30-50%在伤后早期可出现急性肾损伤表现，与预后密切相关，因此探究烧伤后急性肾损伤的干预治疗途径，具有重要意义。机体内部本身存在内源性的损伤保护机制，HO-1是极具潜力的关键酶，本项目系统调查了HO-1介导的内源性保护途径在防治烧伤后急性肾损伤发生发展中的潜在作用及机制细节，寻找新的干预途径。.研究内容：本项目主要以大鼠烫伤模型为研究对象，结合分子生物经典技术手段，明确了烧伤后早期肾脏损伤进展及HO-1表达的变化规律，证实了HO-1作为内源性保护机制的关键酶在防治烧伤后急性肾损伤中的关键作用，阐明了其调控肾损伤机制的作用细节。.结果与关键数据：在本项目研究中，我们发现烧伤后肾组织内氧化应激、细胞凋亡、炎症等损伤机制都随时间持续激活，伤后48小时是肾损伤高峰，而HO-1表达虽在损伤初期有所上调，但随肾损伤加重其表达逐渐下降，提示HO-1介导的内源性防御机制的消耗是烧伤后急性肾损伤进展的原因之一。我们后续利用HO-1诱导剂Hemin验证了HO-1表达诱导有利于缓解烧伤引起的肾组织氧化损伤、细胞凋亡及炎症，TLR4/NF-kappaB途径是HO-1调控的重要下游靶点。我们还依据前期研究基础，证实虾青素可以通过调控HO-1/TLR4/NF-kappaB途径缓解肾组织氧化应激及炎症，进而缓解烧伤后早期肾损伤，为HO-1内源性保护机制的临床转化进行了初步探索。.结论及科学意义：机体可以通过上调HO-1激活内源性保护机制，缓解氧化应激及炎症诱导的烧伤后早期肾损伤，且针对HO-1的药物及诱导剂干预为烧伤早期治疗提供了新的治疗途径，也为临床治疗提供的新的治疗靶点，具备临床转化潜力，并有望扩展到创伤修复的其他领域，具有重要的科学意义。