Tβ4通过下调lncRNA-AIRN抑制肝细胞焦亡缓解急性肝损伤的机制研究

The mortality of liver failure caused by severe acute liver injury is high. We found that hepatocyte pyroptosis was enhanced, together with over-expressed lncRNA-AIRN, in the liver tissue and serum of patients suffered from liver failure; in CCl4-, APAP- and D-gal/LPS- induced acute injured liver in mice; in TNF-α-, H2O2- and serum starvation-induced injured cells; in LPS/Nigericin- and LPS/ATP-induced pyroptotic hepatocytes, respectively. Moreover, knockdown of AIRN reduces LPS/Nigericin-induced hepatocyte pyroptosis. In addition, we found that treatment with Tβ4 reduced the level of AIRN and inhibited hepatocyte pyroptosis. Therefore, we hypothesize that Tβ4 down-regulates AIRN and subsequently reduces hepatocyte pyroptosis, alleviating acute liver injury. Further investigations will focus on the role and mechanism of AIRN and hepatocyte pyroptosis in the process of acute liver injury. Also, we will further detect the level of AIRN in liver and serum with enlarged patient samples, to elucidate the correlation of this molecule with the pathogenesis and prognosis of liver failure, illustrating that AIRN-mediated hepatocyte pyroptosis plays a role in Tβ4-alleviated acute liver injury, thus, confirming AIRN as a novel therapeutic target.

急性肝损伤可导致肝衰竭，病死率很高。我们前期分别在肝衰竭患者、三种急性肝损伤小鼠的肝组织和血清中；TNF-α、H2O2和血清饥饿诱导的肝细胞损伤模型以及LPS/Nigericin和LPS/ATP诱导的体外焦亡模型中发现肝细胞焦亡明显增多，且lncRNA-AIRN过表达；而敲低AIRN则抑制LPS/Nigericin诱导的肝细胞焦亡。此外，发现胸腺素β4（Tβ4）能够下调AIRN并抑制CCl4引起的肝细胞焦亡，明显减轻肝损伤。因此，提出Tβ4通过下调AIRN抑制肝细胞焦亡缓解急性肝损伤的假说。拟进一步在细胞和动物模型中探究AIRN与肝细胞焦亡及急性肝损伤的关系并阐明其作用机制；扩大样本检测AIRN在肝衰竭患者肝组织和血清中的水平，阐明其与肝衰竭发生及预后的关系；阐明Tβ4缓解急性肝损伤是通过抑制AIRN介导的肝细胞焦亡，为肝衰竭的防治提供新靶点。

肝损伤是多种肝病发生与进展的共同病理基础，长链非编码RNA广泛参与多种生理病理过程，是近年来肝脏疾病的研究热点。本课题组探索了两种急性肝损伤模型小鼠中细胞死亡及肝脏再生的动态差异变化并总结其规律，为研究急性肝损伤的发病机制及模型选择提供了强有力的基础依据。此外在肝衰竭患者血清中、小鼠急性肝损伤模型以及体外急性肝损伤模型中筛选出在急性肝损伤过程中过表达且具有物种同源性的 lncRNA-AIRN，通过细胞水平和动物水平实验证明lncRNA-AIRN可减少肝细胞的线粒体损伤，提高小鼠机体的抗氧化能力，抑制氧化应激反应，并且通过调控NF-κB及PI3K-Akt信号通路进而抑制肝细胞凋亡来减轻急性肝损伤。明确lncRNA-AIRN是保护急性肝损伤发生发展的一个重要分子，为治疗急性肝损伤和和肝衰竭提供理论依据和治疗靶标。此外，本课题组在研究过程中还确定lnc-Airn在四氯化碳（CCl4）和胆管结扎（BDL）诱导的小鼠肝纤维化模型中表达上调；并且AIRN在人肝纤维化患者的肝组织和血清中表达量也上调。通过体内实验证实敲除Airn加重CCl4诱导的小鼠肝纤维化，过表达Airn减轻CCl4诱导的小鼠肝纤维化。体外实验证明Airn通过抑制LSECs毛细血管化间接抑制肝星状细胞（HSCs）激活，并且还通过促进LSECs分泌Wnt2a和HGF促进肝细胞（HCs）增殖。在机制研究中，Airn调节转录因子KLF2的表达，并通过KLF2-一氧化氮合酶（eNOS）-鸟苷酸环化酶（sGC）途径维持LSECs分化状态。综上所述，Airn是维持LSECs分化状态的一种新的关键分子，也可成为早期发现和治疗肝纤维化的潜在靶点。该项目对肝纤维化患者的早期诊断、预后评估及防治策略研发开拓了新思路，具有较好的应用前景。