Hsp90 regulation of fibroblast activation in pulmonary fibrosis
Vishwaraj Sontake, … , Anil G. Jegga, Satish K. Madala
Vishwaraj Sontake, … , Anil G. Jegga, Satish K. Madala
Published February 23, 2017
Citation Information: JCI Insight. 2017;2(4):e91454. https://doi.org/10.1172/jci.insight.91454.
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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

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Figure 7

Hsp90 regulates activation of IPF fibroblasts.

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Hsp90 regulates activation of IPF fibroblasts. Primary lung resident fib...
Primary lung resident fibroblasts (CD45–Col1+) were isolated from human idiopathic pulmonary fibrosis (IPF) lung cell cultures and treated with vehicle or 17-AAG. (A) Immunoblot analysis for FAK, p-Tyr576/577FAK, ERK, p-Tyr468ERK, CDC42, and RhoA in the lysates of IPF lung fibroblasts treated with vehicle or 17-AAG (0.5 μM) for 48 hours. (B) The total expression and phosphorylation of the indicated proteins were measured and normalized to GAPDH levels in the total lysates of IPF lung fibroblasts treated with vehicle or 17-AAG (0.5 μM) for 48 hours (n = 3/group). (C) Quantification of CD44, MMP12, and CCR5 gene transcripts relative to GAPDH in IPF lung fibroblasts treated with vehicle or 17-AAG (0.2 μM) for 24 hours (n = 3–6/group). (D) Quantification of CDK4, IGF1, and SPHK1 gene transcripts relative to GAPDH in IPF lung fibroblasts treated with vehicle or 17-AAG (0.2 μM) for 24 hours (n = 6/group). (E) Quantification of COL1α, COL5α, and FN1 gene transcripts relative to GAPDH in IPF lung fibroblasts treated with vehicle or 17-AAG (0.5 μM) for 24 hours (n = 6/group). Data are representative of 2 independent experiments with similar findings. Data shown are mean ± SEM values. *P < 0.05, **P < 0.005, ***P < 0.0005, and ****P < 0.00005.