肝脏淋巴管三维结构动态演变及其在肝硬化门脉高压症中所起作用的研究

Portal hypertension is one of major clinical manifestations of cirrhosis and main cause of death. One of its key mechanisms is related to increase of intrahepatic vascular resistance, when lymphatic vessels are under proliferation and closely associated with formation of ascites. However, whether lymphatic vessels have tiny holes on the surface of cirrhotic liver which contributing to the leakage of asicites along with roles of the lymphatic proliferation in modulation of portal hypertension have not been evaluated yet. We carefully studied histology of cirrhotic liver and found that numbers of lymphatic vessels both under the capsule and inside of liver sections were increased. However this two dimensional observation can not reveal the entire image of lymphatic vessels as a whole. Synchrotron radiation X-ray phase contrast CT has features of high spatial resolution and three dimensional visualization. Using this technique, our preliminary data showed that it can visualize macro and micro lymphatic vessels at the same time and tiny holes on the surface of cirrhotic liver were unexpectedly found. In present study, we are going to visualize hepatic lymphatic vessels in three dimensional manner using the X-ray phase contrast CT technique along with reference to its corresponding histopathology. Carbon tetrachloride and bile duct ligation model in rats with stages of cirrhosis are going to be used to study the changes of lymphatic vessels and its relationship with these tiny holes and portal hypertension. The study would contribute to the understanding of new morphological mechanism of portal hypertension from lymphatic prospective. It could build up a morphological foundation of modulating lymphatic proliferation as a potential new treatment target of portal hypertension.

门脉高压症是肝硬化患者主要临床表现及致死原因。其发病机制之一为血管阻力增加，此时肝脏淋巴系统增生，淋巴管数量增多，淋巴液回流量增加，可从肝被膜渗出参与腹水形成。然而淋巴液是通过怎样的途径渗出肝脏尚缺乏关键形态学证据，增生淋巴系统是否参与门脉压力的调节尚不明确。通过病理形态观察，我们发现肝硬化肝脏表面及内部淋巴管数量均显著增多，然而二维病理图像难以呈现肝脏表面与内部淋巴管的联系。X线相衬CT技术可获得高空间分辨率的软组织微观三维立体结构图像，应用该技术我们同时观察到了肝硬化肝组织表面微细小孔及内部淋巴管样结构。本研究拟采用该技术结合肝脏病理形态，系统观察实验性肝硬化模型发展过程中及肝移植病肝淋巴管三维结构的形态特点，旨在证明其可通过开口于肝脏表面微细小孔而发挥调节门脉压力的作用。本研究是对现有肝硬化门脉高压症发病机制新的理论补充，为发现治疗门脉高压症的新靶点提供病理形态依据。

本研究主要集中揭示于肝硬化门脉高压的形态学机制。通过两种动态模型，即四氯化碳及胆管结扎肝纤维化模型。首先发现现象：四氯化碳肝硬化模型，门脉压力是逐步增高的，而胆管结扎模型门脉压力是骤然升高的，而且在同一时间点，胆管结扎模型门脉压力较四氯化碳模型增加的更为显著。其次，通过二维病理学及三维影像学（同步辐射相称CT）明确了两者间差异的关键形态学机制，即门脉小支缺失的程度在胆管结扎模型中更为普遍、更为突出，并首次从三维角度证明了门脉小支缺失是客观存在的；再次，将动物实验中的发现，在人类胆汁淤积性肝病进行验证（原发性胆汁性肝硬化及胆道闭锁），也证明了门脉支缺失在人类胆汁淤积性肝病中门脉高压症的作用，提示门脉支缺失难以逆转，是防治胆汁淤性肝病的关键靶点。最后，我们探究了门脉支缺失的可能原因：有毒胆汁酸导致内皮细胞的凋亡，进而可导致内皮下胶原暴露及门脉支微血栓形成，门脉支闭塞消失。为查找何种胆汁酸起关键作用，我们利用药物性肝损伤队列，系统筛查了血清胆汁酸谱，发现仅有一种胆汁酸：牛黄酸胆酸与药物性肝损伤严重程度相关，并可预测DILI的预后。.本研究还集中研究了阐明了胆汁性肝硬化进展过程中，细胆管反应的变化规律，从形态学角度，深入解释了胆道压力增高后，细胆管是如何“适应”胆道内压力增高的规律，并进一步解释了该种变化的血供基础。.在本次基金支持下，我研究小组共发表SCI学术论文（论著）10余篇，总影响因子38.553 分，单篇影响因子最高（8.549分）。核心期刊论文 5篇。后续（未来3年内）还会有持续产出，较高影响因子SCI论文发表。我本人晋升为主任医师，三名硕士及一名博士研究生获得学位。.同时必须指出，本课题假说，肝脏表面“小孔”为淋巴管开口，目前证据尚不充分，还不能盲目下结论，就目前的结果看，也可能是由于技术原因，看到的“小孔”仅为血管的终末支走形于包膜下。我们仍在寻求其他技术，进一步明确我们观察到的“小孔”是否真实存在，是否为伪影，其解剖学本质是什么，有明确结论后才能发表以免得出错误结论。