Institution of Hepatology, First Affiliated Teaching Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an City, Shaanxi province, China.
Xi'an Health School, Xi'an City, Shaanxi province, China.
Liver Int. 2017 Nov;37(11):1651-1659. doi: 10.1111/liv.13476. Epub 2017 Jun 22.
BACKGROUND & AIMS: We previously found that hepatic stellate cell activation induced by autophagy maintains the liver architecture to prevent collapse during acute liver failure. Nitric oxide has shown to induce hepatic stellate cell apoptosis. Whether and how nitric oxide is involved in acute liver failure and autophagy remains unclear.
Acute liver failure patients were recruited to investigate the correlation between plasma nitric oxide levels and clinical features. Liver tissues were collected from chronic hepatitis patients by biopsy and from acute liver failure patients who had undergone liver transplantation. The expression of nitric oxide synthases and hepatic stellate cell activation (alpha-SMA), and autophagic activity (LC3) were investigated by immunohistochemistry. Autophagy and apoptosis were investigated by immunoblot analysis, confocal microscopy, and flow cytometry in hepatic stellate cells treated with nitric oxide donors.
Plasma nitric oxide level was significantly increased in patients with acute liver failure compared to those with cirrhosis (53.60±19.74 μM vs 19.40±9.03 μM, Z=-7.384, P<.001) and positively correlated with MELD-Na score (r=.539, P<.001), implicating nitric oxide in acute liver failure. At least some Nitric oxide was produced by overexpression of inducible nitric oxide synthases and endothelial nitric oxide synthases, but not neuronal nitric oxide synthases in the liver tissue. In vivo observation revealed that autophagy was inhibited in hepatic stellate cells based on decreased LC3 immunostaining, and in vitro experiments demonstrated that Nitric oxide can inhibit autophagy. Moreover, nitric oxide promoted hepatic stellate cell apoptosis, which was rescued by an autophagy inducer.
Increased nitric oxide synthases/ nitric oxide promotes apoptosis through autophagy inhibition in hepatic stellate cells during acute liver failure, providing a novel strategy for the treatment of patients with acute liver failure.
我们之前发现，自噬诱导的肝星状细胞活化维持了肝组织结构，防止急性肝衰竭时的崩溃。一氧化氮已被证明能诱导肝星状细胞凋亡。一氧化氮是否以及如何参与急性肝衰竭和自噬仍不清楚。
招募急性肝衰竭患者以研究血浆一氧化氮水平与临床特征之间的相关性。通过活检从慢性肝炎患者和接受肝移植的急性肝衰竭患者中收集肝组织。通过免疫组化研究一氧化氮合酶和肝星状细胞活化（α-SMA）和自噬活性（LC3）的表达。通过免疫印迹分析、共聚焦显微镜和流式细胞术研究一氧化氮供体处理的肝星状细胞中的自噬和凋亡。
与肝硬化患者相比，急性肝衰竭患者的血浆一氧化氮水平显著升高（53.60±19.74 μM 比 19.40±9.03 μM，Z=-7.384，P<.001），并与 MELD-Na 评分呈正相关（r=.539，P<.001），表明一氧化氮与急性肝衰竭有关。至少一些一氧化氮是由诱导型一氧化氮合酶和内皮型一氧化氮合酶的过表达产生的，而不是神经元型一氧化氮合酶在肝组织中产生的。体内观察显示，自噬在肝星状细胞中被抑制，基于 LC3 免疫染色减少，体外实验表明一氧化氮可以抑制自噬。此外，一氧化氮促进肝星状细胞凋亡，自噬诱导剂可挽救这一作用。
在急性肝衰竭期间，增加的一氧化氮合酶/一氧化氮通过自噬抑制促进肝星状细胞凋亡，为急性肝衰竭患者的治疗提供了一种新策略。
