Involvement of TGF-β1/Smad3 Signaling in Carbon Tetrachloride-Induced Acute Liver Injury in Mice.
Involvement of TGF-β1/Smad3 Signaling in Carbon Tetrachloride-Induced Acute Liver Injury in Mice.
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DOI：
10.1371/journal.pone.0156090
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Liu Z
中科院分区：
文献类型：
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作者：
Niu L;Cui X;Qi Y;Xie D;Wu Q;Chen X;Ge J;Liu Z
转化生长因子-β 1（Transforming growth factor-beta1，TGF-β1）是慢性肝损伤发病机制中的主要因素。四氯化碳（CCl 4）是一种肝脏毒物，CCl 4诱导的小鼠肝损伤是化学性肝损伤的经典动物模型。但TGF-β1是否参与了CCl 4诱导的急性化学性肝损伤的过程尚不清楚。本研究旨在探讨转化生长因子β1（TGF-β1）及其信号分子Smad 3在四氯化碳（CCl 4）诱导的急性肝损伤中的作用。结果表明，经肝组织H&E染色证实，CCl 4可有效诱导小鼠急性肝损伤，且与橄榄油对照组相比，CCl 4处理组小鼠血清ALT、AST及TGF-β1水平均显著升高。结果表明，CCl 4染毒小鼠肝组织匀浆中TGF-β1水平明显升高，TGF-β Ⅱ型受体（TβRII）和信号分子Smad 2、3的mRNA表达及Smad 3和磷酸化Smad 3蛋白水平也明显升高。为了阐明TGF-β1/Smad 3信号通路在CCl 4诱导的急性肝损伤中的作用，通过尾静脉注射Smad 3表达质粒在小鼠肝脏中过表达Smad 3。在CCl 4处理后，Smad 3过表达小鼠显示出更严重的肝损伤，通过肝组织的H&E染色和更高的血清ALT和AST水平鉴定。同时，我们发现，与对照组小鼠相比，CCl 4处理的Smad 3过表达小鼠肝脏中有更多的巨噬细胞和中性粒细胞浸润，血清中炎性细胞因子IL-1β和IL-6水平升高。CCl 4处理后，Smad 3过表达小鼠肝细胞凋亡明显增加，凋亡相关蛋白Bax、细胞色素C和切割型caspase 3表达上调。提示TGF-β1/Smad 3信号通路在CCl 4诱导的小鼠急性肝损伤过程中被激活，Smad 3过表达通过促进炎性细胞浸润、炎性细胞因子释放和肝细胞凋亡加重急性肝损伤。结论：TGF-β信号通路的激活参与了CCl 4诱导的急性肝损伤。因此，TGF-β1/Smad 3可能成为急性肝损伤治疗的潜在靶点。
Transforming growth factor-beta1 (TGF-β1) is a major factor in pathogenesis of chronic hepatic injury. Carbon tetrachloride (CCl4) is a liver toxicant, and CCl4-induced liver injury in mouse is a classical animal model of chemical liver injury. However, it is still unclear whether TGF-β1 is involved in the process of CCl4-induced acute chemical liver injury. The present study aimed to evaluate the role of TGF-β1 and its signaling molecule Smad3 in the acute liver injury induce by CCl4. The results showed that CCl4 induced acute liver injury in mice effectively confirmed by H&E staining of liver tissues, and levels of not only liver injury markers serum ALT and AST, but also serum TGF-β1 were elevated significantly in CCl4-treated mice, compared with the control mice treated with olive oil. Our data further revealed that TGF-β1 levels in hepatic tissue homogenate increased significantly, and type II receptor of TGF-β (TβRII) and signaling molecules Smad2, 3, mRNA expressions and Smad3 and phospho-Smad3 protein levels also increased obviously in livers of CCl4-treated mice. To clarify the effect of the elevated TGF-β1/Smad3 signaling on CCl4-induced acute liver injury, Smad3 in mouse liver was overexpressed in vivo by tail vein injection of Smad3-expressing plasmids. Upon CCl4 treatment, Smad3-overexpressing mice showed more severe liver injury identified by H&E staining of liver tissues and higher serum ALT and AST levels. Simultaneously, we found that Smad3-overexpressing mice treated with CCl4 showed more macrophages and neutrophils infiltration in liver and inflammatory cytokines IL-1β and IL-6 levels increment in serum when compared with those in control mice treated with CCl4. Moreover, the results showed that the apoptosis of hepatocytes increased significantly, and apoptosis-associated proteins Bax, cytochrome C and the cleaved caspase 3 expressions were up-regulated in CCl4-treated Smad3-overexpressing mice as well. These results suggested that TGF-β1/Smad3 signaling was activated during CCl4-induced acute liver injury in mice, and Smad3 overexpression aggravated acute liver injury by promoting inflammatory cells infiltration, inflammatory cytokines release and hepatocytes apoptosis. In conclusion, the activation of TGF-β signaling contributes to the CCl4-induced acute liver injury. Thus, TGF-β1/Smad3 may serve as a potential target for acute liver injury therapy.