Protective functions of the bile acid phospholipid conjugate Ursodeoxycholyl Lysophosphatidylethanolamide (UDCA-LPE) during hepatofibrogenesis

肝纤维化通常是由肝脏持续的炎症状况演变而来。随着非酒精性脂肪性疾病（NAFLD）等慢性炎症性肝病发病率的增加，迫切需要新的治疗方法来预防纤维化进展。由于炎症是维持纤维生成的燃料，新的抗纤维化化合物除了能够抑制ECM沉积外，还能抑制肝脏内的炎症反应，这将是可取的。基于某些磷脂（如磷脂酰胆碱）的抗炎特性，本研究组设计了胆汁酸磷脂缀合物熊脱氧胆酰溶血磷脂酰乙醇酰胺（UDCA-LPE）作为一种新型的肝保护剂。我们之前的工作揭示了UDCA-LPE在体外对tnf诱导的细胞毒性具有深刻的抗凋亡和抗炎特性，并进一步证实了其在体内内毒素介导的暴发性肝炎和非酒精性脂肪性肝病（NAFLD）小鼠模型中的肝脏保护功能。在这个DFG应用中，我们的目的是表征UDCA-LPE的抗纤维化功能及其在肝纤维化过程中对促纤维化信号通路的影响。在我们的初步工作中，我们在LX2细胞的星状细胞活化实验模型中，以及在长期MCD饮食导致的晚期非酒精性脂肪性肝炎伴纤维化小鼠模型中，证实了该缀合物的抗纤维化功能。因此，我们现在寻求在原代人肝星状细胞中验证我们的结果，我们的目标是研究有助于抑制tgf介导的信号转导的机制，特别是关于UDCA-LPE抑制Smad3和Smad2的磷酸化。此外，除了偶联物对肝星状细胞的影响外，UDCA-LPE对原代小鼠肝细胞中tgf介导的上皮-间质转化（EMT）的影响将被分析。我们的初步数据显示，UDCA-LPE具有深刻的抗炎特性，这是由于该化合物能够抑制巨噬细胞分泌促炎细胞和趋化因子。因此，我们的目标是研究UDCA-LPE对炎症介质的抑制及其对信号通路的影响，如白细胞介素-6/pStat3通路，该通路在肝纤维化发生过程中发挥重要作用。此外，UDCA-LPE的保护功能将在小鼠体内nash诱导的纤维化和肝癌发生模型中进行分析。这些结果将有助于确定UDCA-LPE的精确抗纤维化谱，以及该偶联物在预防慢性肝病纤维化进展方面的潜在治疗应用。

Liver fibrosis generally evolves from persisting inflammatory conditions of the liver. With increasing incidence of chronic inflammatory liver diseases such as non-alcoholic fatty disease (NAFLD), new therapeutic approaches to prevent fibrotic progression are urgently needed. As inflammation is the fuel perpetuating fibrogenesis, new anti-fibrogenic compounds capable of dampening inflammatory response within the liver in addition to the ability to inhibit ECM deposition would be desirable. Based upon the anti-inflammatory properties of certain phospholipids such as phosphatidylcholine the bile acid phospholipid conjugate Ursodeoxycholyl Lysophosphatidylethanolamide (UDCA-LPE) was designed in our group as a novel hepatoprotective agent. Our previous work revealed profound anti-apoptotic and anti-inflammatory properties of UDCA-LPE against TNF-induced cytotoxicity in vitro and further confirmed hepatoprotective functions in mouse models of endotoxin-mediated fulminant hepatitis and non-alcoholic fatty liver disease (NAFLD) in vivo. In this DFG application, we aim to characterize anti-fibrogenic functions of UDCA-LPE and its influence on pro-fibrogenic signalling pathways during hepatofibrogenesis. In our preliminary work we confirmed anti-fibrogenic functions of the conjugate in experimental models of stellate cell activation in LX2 cells, as well as in a mouse model of advanced non-alcoholic steatohepatitis with fibrosis due to long-term MCD diet. Thus, we now pursue to verify our results in primary human hepatic stellate cells and we aim to study the mechanisms contributing to an inhibition of TGF-mediated signal transduction especially regarding the suppressed phosphorylation of Smad3 and Smad2 due to UDCA-LPE. Moreover, besides the influence of the conjugate on hepatic stellate cells the effect of UDCA-LPE on TGF-mediated epithelial-to-mesenchymal transition (EMT) will be analyzed in primary mouse hepatocytes. Our preliminary data showed profound anti-inflammatory properties of UDCA-LPE due to the ability of the compound to inhibit the secretion of pro-inflammatory cyto- and chemokines by macrophages. Thus, we aim to study the suppression of inflammatory mediators by UDCA-LPE with respect to its impact on signalling pathways like e.g. the Interleukin-6/pStat3 pathway, which is supposed to play an important role during hepatofibrogenesis. Furthermore, protective functions of UDCA-LPE will be analyzed in a mouse model of NASH-induced fibrosis and hepatocarcinogenesis in vivo. The results will help to define a precise anti-fibrogenic profile of UDCA-LPE with respect to potential therapeutic applications of the conjugate for the prevention of fibrogenic progression of chronic liver disease.