内源性气体信号分子一氧化氮(NO)具有广泛的生物学功能，在体内由一氧化氮合酶精准调控产生以维持体内稳态平衡。肝硬化患者肝窦内NO水平降低，导致肝内门静脉高压，补充外源性NO能够缓解门静脉高压。目前已开发出很多NO供体药物用于治疗门静脉高压并显示出很好的疗效，但是由于难以靶向精准递送而无法满足临床应用。针对上述问题，前期工作中我们利用“凸凹互补”策略得到酶控NO定点释放体系“工程化酶-NO前药”，在此基础上本项目拟进一步利用凝集素导向酶激活前药疗法(LEAPT)两步药物递送策略设计肝靶向NO精准递送体系：合成糖基缀合物并对工程化酶表面进行糖基化修饰，利用肝细胞表面特异性高表达的去唾液酸糖蛋白受体(ASGPr)和糖配体的亲和力将工程化酶选择性递送到肝细胞中，进而在肝细胞中水解糖基化NO供体前药，从而实现NO靶向肝细胞精准递送，并在肝硬化模型中评价其对门静脉高压症的缓解作用。

The spatiotemporal generation of nitric oxide (NO), a versatile endogenous messenger, is precisely controlled by nitric oxide synthase in the body to maintain homeostasis. A reduced level of NO in the hepatic sinusoids of cirrhotic patients leads to intrahepatic portal hypertension. Indeed, replenishing NO in the injured liver ameliorates portal hypertension. So far, many NO-donor drugs have been developed for portal hypertension that showed good efficacy in animal and clinical trials, but the conventional NO donors still can’t meet the clinical demand due to their nonspecific in vivo distribution. To address these issues, we developed a novel NO delivery system “engineered galactosidase-NO prodrug” pair via “bump-and-hole” strategy, which ensure the NO specific release at the site of engineered enzyme. Based on the previous work, the lectin-directed enzyme activated prodrug therapy bipartite drug delivery system will be further adopted to design a liver-selective NO system. Here, the engineered galactosidase will be coated with sugar cluster, which could localize the engineered galactosidase conjugates to liver cell by sugar-mediated receptor-mediated endocytosis, via the asialoglycoprotein receptor. The second step involves administering the capped NO prodrug, which is activated in the hepatocyte by the pre-delivered engineered galactosidase. The therapeutic effectiveness of the hepatic-specific NO system will be evaluated in portal hypertension.