Free fatty acids induce ER stress and block antiviral activity of interferon alpha against hepatitis C virus in cell culture.
Free fatty acids induce ER stress and block antiviral activity of interferon alpha against hepatitis C virus in cell culture.
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DOI：
10.1186/1743-422x-9-143
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发表时间：
2012-08-03
期刊：
影响因子：
4.8
通讯作者：
Dash S
中科院分区：
文献类型：
--
作者：
Gunduz F;Aboulnasr FM;Chandra PK;Hazari S;Poat B;Baker DP;Balart LA;Dash S
在慢性丙型肝炎(CHC)患者中，肝脏脂肪变性被认为是肝脏疾病进展和干扰素治疗反应受损的主要危险因素。在肝脏脂肪变性的情况下，干扰素-α治疗的反应机制尚不清楚。我们在细胞培养模型中研究了肝细胞脂肪变性对丙型肝炎病毒复制和干扰素-α抗病毒反应的影响。用饱和(棕榈酸)和不饱和(油酸)长链游离脂肪酸(FFA)混合培养亚基因组复制子(S3-GFP)和丙型肝炎病毒感染的Huh-7.5细胞。尼罗红染色和电子显微镜观察这些细胞胞浆内脂肪的积聚，然后用显微荧光法进行定量。通过流式细胞仪分析、雷尼拉荧光素酶活性和实时荧光定量RT-α检测荧光抗体对丙型肝炎病毒复制和干扰素-DNA抗病毒应答的影响。尼罗红染色、显微荧光法和电子显微镜证实，FFA处理可引起剂量依赖性的肝细胞脂肪变性和丙型肝炎病毒复制子细胞中的脂滴聚集。在持续感染丙型肝炎病毒的培养中，细胞内脂肪积累比在亚基因组复制子(S3-GFP)细胞系中更支持复制。FFA治疗还通过减少STAT1和STAT2依赖的干扰素-α启动子的磷酸化来部分阻断干扰素-β的应答和病毒清除。我们发现，FFA治疗诱导内质网(ER)应激反应，下调I型干扰素受体的IFNAR1链，导致Jak-Stat信号转导缺陷和抗病毒反应受损。这些结果表明，丙型肝炎病毒细胞培养中的细胞内脂肪积聚诱导了ER应激，JAK-STAT信号转导缺陷，并减弱了抗病毒反应，从而为临床观察肝细胞脂肪变性如何影响慢性丙型肝炎患者干扰素-α反应提供了解释。
Hepatic steatosis is recognized as a major risk factor for liver disease progression and impaired response to interferon based therapy in chronic hepatitis C (CHC) patients. The mechanism of response to interferon-alpha (IFN-α) therapy under the condition of hepatic steatosis is unexplored. We investigated the effect of hepatocellular steatosis on hepatitis C virus (HCV) replication and IFN-α antiviral response in a cell culture model. Sub-genomic replicon (S3-GFP) and HCV infected Huh-7.5 cells were cultured with a mixture of saturated (palmitate) and unsaturated (oleate) long-chain free fatty acids (FFA). Intracytoplasmic fat accumulation in these cells was visualized by Nile red staining and electron microscopy then quantified by microfluorometry. The effect of FFA treatment on HCV replication and IFN-α antiviral response was measured by flow cytometric analysis, Renilla luciferase activity, and real-time RT-PCR. FFA treatment induced dose dependent hepatocellular steatosis and lipid droplet accumulation in the HCV replicon cells was confirmed by Nile red staining, microfluorometry, and by electron microscopy. Intracellular fat accumulation supports replication more in the persistently HCV infected culture than in the sub-genomic replicon (S3-GFP) cell line. FFA treatment also partially blocked IFN-α response and viral clearance by reducing the phosphorylation of Stat1 and Stat2 dependent IFN-β promoter activation. We show that FFA treatment induces endoplasmic reticulum (ER) stress response and down regulates the IFNAR1 chain of the type I IFN receptor leading to defective Jak-Stat signaling and impaired antiviral response. These results suggest that intracellular fat accumulation in HCV cell culture induces ER stress, defective Jak-Stat signaling, and attenuates the antiviral response, thus providing an explanation to the clinical observation regarding how hepatocellular steatosis influences IFN-α response in CHC.