Hepatocyte free cholesterol lipotoxicity results from JNK1-mediated mitochondrial injury and is HMGB1 and TLR4-dependent
Hepatocyte free cholesterol lipotoxicity results from JNK1-mediated mitochondrial injury and is HMGB1 and TLR4-dependent
复制标题
DOI：
10.1016/j.jhep.2014.07.024
复制
发表时间：
2014-12-01
影响因子：
25.7
通讯作者：
Farrell, Geoffrey C.
中科院分区：
文献类型：
--
作者：
Gan, Lay T.;Van Rooyen, Derrick M.;Farrell, Geoffrey C.
背景与目的：游离胆固醇（FC）在非酒精性脂肪性肝炎（NASH）中蓄积，但在单纯性脂肪变性中不蓄积。我们试图建立如何FC导致肝细胞injure.Methods：在NASH影响的糖尿病小鼠的肝脏，亚细胞FC分布（菲律宾荧光）建立了亚细胞标记物共定位。采用低密度脂蛋白（LDL）诱导小鼠肝细胞负载FC，研究FC对JNK 1激活、线粒体损伤和细胞死亡的影响，以及对高迁移率族蛋白1（HMGB 1）和Toll样受体4（TLR 4）扩增作用的影响。这在负载FC的肝细胞中重现。在40 μ M LDL时，肝细胞FC增加，导致与JNK 1激活（c-Jun磷酸化）、线粒体膜孔转换、细胞色素c释放、氧化应激（GSSG：GSH比）和ATP耗竭相关的LDH泄漏、凋亡和坏死。电镜下可见线粒体肿胀和晶体排列紊乱。JNK 1（-/-）和Tlr 4（-/-）肝细胞对FC脂毒性不敏感; JNK抑制剂（1-2 μ M CC-401、CC-930）阻断细胞凋亡和坏死。环孢素A和半胱天冬酶-3抑制剂保护FC负载的肝细胞，证实线粒体细胞死亡途径;相反，4-苯基丁酸，提高ER折叠能力没有保护FC负载的肝细胞。HMGB 1被释放到培养基中的FC加载野生型（WT），但不是JNK 1（-/-）或Tlr 4（-/-）肝细胞，而抗HMGB 1抗血清阻止JNK激活和FC脂毒性在WT hepatocyte.Conclusions：这些新的研究结果表明，线粒体FC沉积引起肝细胞凋亡和坏死激活JNK 1;抑制这可能是一种新的治疗方法在NASH。此外，脂毒性肝细胞的JNK 1依赖性HMGB 1分泌与通过TLR 4对邻近胆固醇负载肝细胞的旁分泌细胞溶解作用之间存在紧密联系。(C)2014由Elsevier B. V.代表欧洲肝脏研究协会发表。
Background & Aims: Free cholesterol (FC) accumulates in nonalcoholic steatohepatitis (NASH) but not in simple steatosis. We sought to establish how FC causes hepatocyte injury.Methods: In NASH-affected livers from diabetic mice, subcellular FC distribution (filipin fluorescence) was established by subcellular marker co-localization. We loaded murine hepatocytes with FC by incubation with low-density lipoprotein (LDL) and studied the effects of FC on JNK1 activation, mitochondrial injury and cell death and on the amplifying roles of the high-mobility-group-box 1 (HMGB1) protein and the Toll-like receptor 4 (TLR4).Results: In NASH, FC localized to hepatocyte plasma membrane, mitochondria and ER. This was reproduced in FC-loaded hepatocytes. At 40 mu M LDL, hepatocyte FC increased to cause LDH leakage, apoptosis and necrosis associated with JNK1 activation (c-Jun phosphorylation), mitochondrial membrane pore transition, cytochrome c release, oxidative stress (GSSG:GSH ratio) and ATP depletion. Mitochondrial swelling and crystae disarray were evident by electron microscopy. Jnk1(-/-) and Tlr4(-/-) hepatocytes were refractory to FC lipotoxicity; JNK inhibitors (1-2 mu M CC-401, CC-930) blocked apoptosis and necrosis. Cyclosporine A and caspase-3 inhibitors protected FC-loaded hepatocytes, confirming mitochondrial cell death pathways; in contrast, 4-phenylbutyric acid, which improves ER folding capacity did not protect FC-loaded hepatocytes. HMGB1 was released into the culture medium of FC-loaded wild type (WT) but not Jnk1(-/-) or Tlr4(-/-) hepatocytes, while anti-HMGB1 anti-serum prevented JNK activation and FC lipotoxicity in WT hepatocytes.Conclusions: These novel findings show that mitochondrial FC deposition causes hepatocyte apoptosis and necrosis by activating JNK1; inhibition of which could be a novel therapeutic approach in NASH. Further, there is a tight link between JNK1-dependent HMGB1 secretion from lipotoxic hepatocytes and a paracrine cytolytic effect on neighbouring cholesterol-loaded hepatocytes operating via TLR4. (C) 2014 Published by Elsevier B.V. on behalf of the European Association for the Study of the Liver.