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Heat shock protein 90 (Hsp90) inhibition targets canonical TGF-β signalling to prevent fibrosis
  1. Michal Tomcik1,2,
  2. Pawel Zerr1,
  3. Jana Pitkowski1,
  4. Katrin Palumbo-Zerr1,
  5. Jérôme Avouac1,3,
  6. Oliver Distler4,
  7. Radim Becvar2,
  8. Ladislav Senolt2,
  9. Georg Schett1,
  10. Jörg H Distler1
  1. 1Department of Internal Medicine 3 and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany
  2. 2First Faculty of Medicine, Department of Rheumatology, Institute of Rheumatology, Charles University in Prague, Prague, Czech Republic
  3. 3 Rheumatology A Department and INSERM U1016 Cochin Hospital, Paris Descartes University, Paris, France
  4. 4Center of Experimental Rheumatology and Zurich Center of Integrative Human Physiology, University Hospital, Zurich, Switzerland
  1. Correspondence to Dr Michal Tomcik, First Faculty of Medicine, Department of Rheumatology, Institute of Rheumatology, Charles University, Na Slupi 4, 128 50 Prague 2, Czech Republic; michaltomcik{at}yahoo.com

Abstract

Objectives Targeted therapies for systemic sclerosis (SSc) and other fibrotic diseases are not yet available. We evaluated the efficacy of heat shock protein 90 (Hsp90) inhibition as a novel approach to inhibition of aberrant transforming growth factor (TGF)-β signalling and for the treatment of fibrosis in preclinical models of SSc.

Methods Expression of Hsp90 was quantified by quantitative PCR, western blot and immunohistochemistry. The effects of Hsp90 inhibition were analysed in cultured fibroblasts, in bleomycin-induced dermal fibrosis, in tight-skin (Tsk-1) mice and in mice overexpressing a constitutively active TGF-β receptor I (TβRI).

Results Expression of Hsp90β was increased in SSc skin and in murine models of SSc in a TGF-β-dependent manner. Inhibition of Hsp90 by 17-dimethylaminoethylamino-17-demethoxy-geldanamycin (17-DMAG) inhibited canonical TGF-β signalling and completely prevented the stimulatory effects of TGF-β on collagen synthesis and myofibroblast differentiation. Treatment with 17-DMAG decreased the activation of canonical TGF-β signalling in murine models of SSc and exerted potent antifibrotic effects in bleomycin-induced dermal fibrosis, in Tsk-1 mice and in mice overexpressing a constitutively active TβRI. Dermal thickness, number of myofibroblasts and hydroxyproline content were all significantly reduced on treatment with 17-DMAG. No toxic effects were observed with 17-DMAG at antifibrotic doses.

Conclusions Hsp90 is upregulated in SSc and is critical for TGF-β signalling. Pharmacological inhibition of Hsp90 effectively blocks the profibrotic effects of TGF-β in cultured fibroblasts and in different preclinical models of SSc. These results have translational implications, as several Hsp90 inhibitors are in clinical trials for other indications.

  • Fibroblasts
  • Systemic Sclerosis
  • Treatment

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