TLR4/MyD88/NF-kB信号通路在泡状棘球蚴感染所致肝脏再生的免疫机制研究

Hepatic alveolar echinococcosis (HAE), also known as “parasitic cancer”, is caused by the larval stage of the tapeworm Echinococcus multilocularis (E.m) and still imposes great threat on health. Radical hepatic resection and liver auto-transplantation are priority. However, post-operative liver dysfunction is a major obstacle for surgical success. A series of previous works of us have revealed an obvious liver regeneration in HAE patients and E.m infected murine model and postulated a correlation between the immune regulation on host’s Kupffer cells and the secretion of inflammatory cytokine IL-6. Nonetheless, the possible pathways and molecular mechanism are still remained unknown. This research aims at the immunological role of TLR4/MyD88/NF-kB pathway and its possible mechanism in liver regeneration caused by E.m infection by using flow cytometry, Western-Blot, immunohistochemistry and gene knockout mice, further find out the key cytokine and molecules that may play significant role in the regulation of liver regeneration. In addition, the possible mechanism of E.m/TLR4/MyD88/NF-kB/STAT3/IL-6 signal transduction pathway during liver regeneration caused by E.m infection will be studied. This study may provide theoretical support for immunological mechanism and to prevent the post-operative liver dysfunction during E.m infection.

肝泡型包虫病亦称“虫癌”是由泡状棘球蚴绦虫（E.m）感染所致的严重危害百姓健康的人畜共患病。肝切除和自体肝移植仍是根治措施。术后肝功不全是影响手术成功的关键因素。我们系列研究结果提示，肝泡型包虫病患者和E.m感染小鼠健侧肝明显再生，提示可能和E.m感染对宿主Kupffer细胞的调节和介导炎性因子IL-6表达有关。但其具体途径和可能的区域分子免疫机制未知。本研究计划利用人体组织标本和动物模型，通过流式技术，基因敲除鼠，Western Blot，免疫组化等技术，从体内外实验体系和临床患者等多个水平，了解感染状态下Kupffer细胞成熟分化和抗原呈递功能变化，继而解析E.m驯化的Kupffer 细胞对肝再生的影响，并最终在E.m/TLR4/MyD88/NF-κB/STAT3/IL-6信号转导途径免疫应答轴中发现关键作用因子，为阐明肝泡型包虫所致肝再生的区域分子免疫机制和预防肝功不全提供理论依据。

肝脏泡型包虫病（alveolar echinococcosis, AE）是由多房棘球蚴绦虫（echinococcus multilocularis, E. multilocularis）感染所致的人蓄共患病。肝泡型包虫病具有肿瘤样浸润性生长特点，往往侵犯肝内主要脉管，临床上亦称“虫癌”。肝切除和肝移植是治疗肝泡型包虫病的根治性措施。然而，术后肝功能不全仍是影响手术结局的关键因素。我们通过建立E. multilocularis感染小鼠的肝部分切除术模型，研究E. multilocularis感染对肝切除术后肝再生状态的影响，观察TLR4/MyD88信号通路的变化规律，探究E. multilocularis感染对肝切除术后肝再生的影响和免疫分子机制。我们通过临床样本研究泡型包虫患者肝脏区域和循环免疫应答调节及其特征性应答模式和肝部分切除术后肝再生的潜在联系，并借助动物实验研究进一步验证。我们研究发现C57BL/6小鼠皮下感染E. multilocularis模型具有操作简便、可重复性强、感染率高和便于观察等优点。与对照组相比，皮下感染E. multilocularis小鼠肝切除术后肝再生相关启动因子表达降低和终止因子表达水平升高，延迟了肝再生过程。皮下感染E. multilocularis小鼠肝切除术后肝再生的延缓可能与感染所致宿主免疫耐受有关。结合我们团队既往的系列研究结果，肝脏AE感染过程有Th1/Th2/Th9/Th17/Treg免疫应答模式可能参与免疫逃避与免疫病理损伤过程。Th2和Treg细胞优势型免疫应答模式与虫体感染致宿主免疫耐受和虫体持续浸润性生长有关；而Th17优势型免疫应答可能与疾病进展和免疫病理损伤过程。血浆IL-23水平很可能与疾病进展和转归有关，可能成为评价病灶活性和治疗效果的指标。不同活性状态泡型包虫病TLRs差异化表达是泡型包虫感染延迟肝脏再生的可能机制之一。研究结果为阐明肝泡型包虫所致肝再生的区域分子免疫机制，预测和提早干预术后肝功能不全提供一定的科学理论依据和实践指导。将来仍需要进一步深入研究其相关机制并应用于临床实践。