Hsp90 regulation of fibroblast activation in pulmonary fibrosis
Vishwaraj Sontake, Yunguan Wang, Rajesh K. Kasam, Debora Sinner, Geereddy B. Reddy, Anjaparavanda P. Naren, Francis X. McCormack, Eric S. White, Anil G. Jegga, Satish K. Madala
Vishwaraj Sontake, Yunguan Wang, Rajesh K. Kasam, Debora Sinner, Geereddy B. Reddy, Anjaparavanda P. Naren, Francis X. McCormack, Eric S. White, Anil G. Jegga, Satish K. Madala
View: Text | PDF
Research Article Immunology Pulmonology

Hsp90 regulation of fibroblast activation in pulmonary fibrosis

Abstract

Idiopathic pulmonary fibrosis (IPF) is a severe fibrotic lung disease associated with fibroblast activation that includes excessive proliferation, tissue invasiveness, myofibroblast transformation, and extracellular matrix (ECM) production. To identify inhibitors that can attenuate fibroblast activation, we queried IPF gene signatures against a library of small-molecule-induced gene-expression profiles and identified Hsp90 inhibitors as potential therapeutic agents that can suppress fibroblast activation in IPF. Although Hsp90 is a molecular chaperone that regulates multiple processes involved in fibroblast activation, it has not been previously proposed as a molecular target in IPF. Here, we found elevated Hsp90 staining in lung biopsies of patients with IPF. Notably, fibroblasts isolated from fibrotic lesions showed heightened Hsp90 ATPase activity compared with normal fibroblasts. 17-N-allylamino-17-demethoxygeldanamycin (17-AAG), a small-molecule inhibitor of Hsp90 ATPase activity, attenuated fibroblast activation and also TGF-β–driven effects on fibroblast to myofibroblast transformation. The loss of the Hsp90AB, but not the Hsp90AA isoform, resulted in reduced fibroblast proliferation, myofibroblast transformation, and ECM production. Finally, in vivo therapy with 17-AAG attenuated progression of established and ongoing fibrosis in a mouse model of pulmonary fibrosis, suggesting that targeting Hsp90 represents an effective strategy for the treatment of fibrotic lung disease.

Authors

Vishwaraj Sontake, Yunguan Wang, Rajesh K. Kasam, Debora Sinner, Geereddy B. Reddy, Anjaparavanda P. Naren, Francis X. McCormack, Eric S. White, Anil G. Jegga, Satish K. Madala

×

Figure 5

Hsp90 regulates αSMA and extracellular matrix gene expression.

Options: View larger image (or click on image) Download as PowerPoint
Hsp90 regulates αSMA and extracellular matrix gene expression. Primary l...
Primary lung fibroblasts (CD45–Col1+) isolated from lung fibroblast cultures of TGF-α–transgenic mice on doxycycline (Dox) for 4 weeks and treated with vehicle or 17-AAG and control, Hsp90AA-specific, or Hsp90AB-specific siRNA. (A) Quantification of αSma, Fn1, Col1α and Col5α gene transcripts relative to Hprt in the lung-resident fibroblasts treated with vehicle or 17-AAG (1 μM) for 24 hours. Data are cumulative of 3 independent experiments with similar findings (n = 3/group). (B) Quantification of αSma, Fn1, Col1α, and Col5α gene transcripts relative to Hprt in the lung-resident fibroblasts treated with control, Hsp90AA-specific, or Hsp90AB-specific siRNA for 72 hours. Data are cumulative of 2 independent experiments with similar findings (n = 3–4/group). (C) Immunoblots for αSMA and FN1 in the lysates of lung fibroblasts treated with vehicle or 17-AAG (1 μM) for 48 hours. (D) Quantification of αSMA and FN1 proteins normalized to GAPDH levels in the total lysates of lung fibroblasts treated with vehicle or 17-AAG (1 μM) for 24 hours. Data are representative of 2 independent experiments with similar findings (n = 3/group). Data shown are mean ± SEM. An unpaired 2-tailed Student’s t test was performed to measure the significance. *P < 0.05, **P < 0.005, and ***P < 0.0005.