Elsevier

European Journal of Pharmacology

Volume 791, 15 November 2016, Pages 482-490
European Journal of Pharmacology

Molecular and cellular pharmacology
Induction of heat shock protein 27 by bicyclol attenuates d-galactosamine/lipopolysaccharide-induced liver injury

https://doi.org/10.1016/j.ejphar.2016.09.002Get rights and content

Abstract

Heat shock proteins (Hsps) are critical for cell survival under adverse environmental conditions. Bicyclol is a novel hepatoprotectant that has been shown to protect against liver injury by inducing Hsps, including Hsp27 and Hsp70. Although the role of Hsp70 in protecting against acute hepatic failure has been clearly explored, the precise function of Hsp27 in this setting is poorly defined. This study was undertaken to evaluate the role of Hsp27 in bicyclol-mediated hepatoprotection. Both primary hepatocytes and bone marrow-derived macrophages were subjected to bicyclol treatment, followed by detection of Hsp27 expression. Adenoviruses containing the mouse Hsp27 coding sequence or shRNA interference sequence targeting Hsp27 were used to manipulate Hsp27 expression in the liver before the mice were treated with bicyclol and/or confronted with D-galactosamine/lipopolysaccharide (Galn/LPS)-induced acute liver damage. Only hepatocytes increased their Hsp27 expression after bicyclol treatment and the time course of bicyclol-induced Hsp27 expression in hepatocytes was in line with the in vivo results. Although high-dose bicyclol could protect against liver failure without Hsp27, the effect of bicyclol given at a low dose was dependent on Hsp27 induction. Adenovirus-mediated transduction of Hsp27 protected against acute liver damage and partially replicated the protective effect afforded by bicyclol. These results demonstrated that bicyclol induced Hsp27 expression in hepatocytes, which was essential to bicyclol-mediated hepatoprotection. Overexpression of Hsp27 in hepatocytes could confer remarkable protection against acute liver damage.

Introduction

Hsp27 belongs to a family of abundant and ubiquitous stress proteins, the small heat shock proteins (sHsp), which are detectable in virtually all organisms from prokaryotes to mammals and serve as molecular chaperones to refold denatured proteins or promote the degradation of damaged proteins. Although Hsp27 is a multi-functional regulator (Kostenko and Moens, 2009), its cytoprotective effect is largely explained by its anti-apoptotic function. Hsp27 has been shown to interact with different key apoptotic proteins, block essentially all apoptotic pathways, and ultimately determine the fate of cells under different kinds of lethal conditions (Concannon et al., 2003).

Fulminant hepatic failure is a dramatic clinical syndrome that results from lethal hepatocyte damage. Although studies have repeatedly demonstrated that the main morphological feature of fulminant hepatic failure is hepatocyte apoptosis (Liu et al., 2008), direct evidence of the role of Hsp27 in protecting against fulminant hepatic failure is absent. It has been reported that oral administration of a novel anti-hepatitis drug bicyclol, which protects against fulminant hepatic failure in different kinds of mouse models, resulted in hepatic Hsp27/70 overexpression in a time- and dose-dependent manner (Liu et al., 2008, Bao and Liu, 2009). The protective effect of bicyclol on acute liver injury was reported to be markedly attenuated in mouse models by quercetin, an inhibitor of Hsp synthesis. However, the possibility still exists that the mechanism is indirect. The small Hsp family contains more than ten members, and at least four of them are known to be ubiquitously expressed (Garrido et al., 2012). Bicyclol can also significantly induce the expression of hepatic Hsp70, which is one of the best-known endogenous factors protecting cells and tissues against injuries under various pathologic conditions (Minowada and Welch, 1995). So, the role of Hsp27 in the pharmacological action of bicyclol still remains to be elucidated.

Adenovirus-mediated transgene delivery and RNA interference are powerful techniques for specifically promoting or inhibiting target gene expression. Adenovirus has also proven to be a valuable gene delivery vector in vivo with special tropism for the liver (Smith et al., 2002, Suetsugu et al., 2005). In this study, we used adenoviruses to target Hsp27 in a mouse model of fulminant hepatic failure induced by D-galactosamine/lipopolysaccharide(Galn/LPS) to investigate the role of Hsp27 in bicyclol-induced hepatic protection.

Section snippets

Animals

All mice were purchased from Shanghai SLAC Laboratory Animal Co. Ltd (Shanghai, China). Male C57BL/6 mice 8 to 12 weeks old (20–25 g) were used in the study. The mice were housed in a pathogen-free facility and handled in accordance with standard use protocols, animal welfare regulations, and the institutional guidelines of Shanghai Jiaotong University School of Medicine, the Regulations for Practice of Experimental Animals (issued by Scientific and Technical Committee, P.R.China, 1988), and the

Bicyclol induces Hsp27 expression in hepatocytes rather than macrophages

Although it has been reported that bicyclol induces the expression of hepatic Hsp27 (Bao and Liu, 2009), the effects of bicyclol on specific cell populations have not been determined thus far. In addition to a possible protective effect on hepatocytes, Hsps have been reported to inhibit TNF-α expression in macrophages (Singh et al., 2000), and thus might play a role in alleviating inflammation-induced damage. Therefore, both bone marrow-derived macrophages and primary hepatocytes were employed

Discussion

Acute liver failure is a worldwide clinical problem with a very high mortality. The number of pharmaceutical agents that attenuate liver injury in humans is actually very limited, and a sizable proportion of them are used in a more or less empirical manner. Bicyclol(4,4′-dimethoxy-5,6,5′,6′-Bis(dimethylene-dioxy)-2-hydroxymethyl-20-methoxy carbonyl biphenyl; Fig. 7), which is of Chinese medicinal herbal origin, has been used as a hepatoprotective agent for the treatment of patients with

Conclusion

Taken together, our studies demonstrate that bicyclol induces Hsp27 expression in hepatocytes, which is essential to bicyclol-mediated hepatoprotection. Expression of Hsp27 in hepatocytes confers remarkable protection against acute liver damage.

Acknowledgments

This work was supported by grants from the National Natural Science Foundation of China, China (grant number 81470895 to MZ, and grant number 81270558 to QX).

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    Hui-Juan DAI, Da-Wei LI and Ya-Xiang WANG contributed equally to this paper.

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