Inhibition of heat shock protein (molecular weight 90 kDa)... : Hepatology (original) (raw)
Liver Biology/Pathobiology
Inhibition of heat shock protein (molecular weight 90 kDa) attenuates proinflammatory cytokines and prevents lipopolysaccharide-induced liver injury in mice
Ambade, Aditya1; Catalano, Donna1; Lim, Arlene1; Mandrekar, Pranoti1,*,†
1 From the Department of Medicine, University of Massachusetts Medical School, Worcester, MA
* Address reprint requests to: Department of Medicine, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605.
E-mail:[email protected]
Received 8 July 2011; Accepted 2 November 2011
This work was supported by Public Health Service grant no. AA017986 (to P.M.) from the National Institute of Alcohol Abuse and Alcoholism (NIAAA) and its contents are the sole responsibility of the authors and do not necessarily represent the views of the NIAAA. This work was also supported by the University of Massachusetts Center for AIDS Research (P30 AI042845).
Potential conflict of interest: Nothing to report.
† fax: (508) 856-4770
Additional Supporting Information may be found in the online version of this article.
View this article online atwileyonlinelibrary.com.
Abstract
Endotoxin-mediated proinflammatory cytokines play a significant role in the pathogenesis of acute and chronic liver diseases. Heat shock protein 90 (molecular weight, 90 kDa) (hsp90) functions as an important chaperone of lipopolysaccharide (LPS) signaling and is required for the production of proinflammatory cytokines. We hypothesized that inhibition of hsp90 would prevent LPS-induced liver injury by decreasing proinflammatory cytokines. C57BL/6 mice were injected intraperitoneally with an hsp90 inhibitor, 17-dimethylamino-ethylamino-17-demethoxygeldanamycin (17-DMAG), and LPS. Parameters of liver injury, proinflammatory cytokines, and associated mechanisms were studied by in vivo and in vitro experiments. Inhibition of hsp90 by 17-DMAG prevented LPS-induced increases in serum alanine aminotransferase activity and significantly reduced serum tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6) protein as well as messenger RNA (mRNA) in liver. Enhanced DNA-binding activity of heat shock transcription factor 1 (HSF1) and induction of target gene heat shock protein 70 (molecular weight, 70 kDa) confirmed hsp90 inhibition in liver. 17-DMAG treatment decreased cluster of differentiation 14 mRNA and LPS-induced nuclear factor kappa light-chain enhancer of activated B cells (NFκB) DNA binding without affecting Toll-like receptor 4 mRNA in liver. Mechanistic studies revealed that 17-DMAG-mediated inhibition of TNFα showed no effect on LPS-induced NFκB promoter-driven reporter activity, but significantly decreased TNFα promoter-driven reporter activity. Chromatin immunoprecipitation assays showed that 17-DMAG enhanced HSF1 binding to the TNFα promoter, but not the IL-6 promoter, suggesting HSF1 mediated direct inhibition of TNFα, but not IL-6. We show that HSF1 indirectly regulates IL-6 by the induction of another transcription factor, activating transcription factor 3. Inhibition of HSF1, using small interfering RNA, prevented 17-DMAG-mediated down-regulation of NFκB-binding activity, TNFα, and IL-6 induction, supporting a repressive role for HSF1 on proinflammatory cytokine genes during hsp90 inhibition.
Conclusion:
Hsp90 inhibition in vivo reduces proinflammatory cytokines and prevents LPS-induced liver injury likely through repressive action of HSF1. Our results suggest a novel application for 17-DMAG in alleviating LPS-induced liver injury. (Hepatology 2011)
Copyright © 2012 American Association for the Study of Liver Diseases.