Attenuation of lung fibrosis in mice with a clinically relevant inhibitor of glutathione-S-transferase π
David H. McMillan, … , Vikas Anathy, Yvonne M.W. Janssen-Heininger
David H. McMillan, … , Vikas Anathy, Yvonne M.W. Janssen-Heininger
Published June 2, 2016
Citation Information: JCI Insight. 2016;1(8):e85717. https://doi.org/10.1172/jci.insight.85717.
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Research Article Pulmonology Therapeutics

Attenuation of lung fibrosis in mice with a clinically relevant inhibitor of glutathione-S-transferase π

Abstract

Idiopathic pulmonary fibrosis (IPF) is a debilitating lung disease characterized by excessive collagen production and fibrogenesis. Apoptosis in lung epithelial cells is critical in IPF pathogenesis, as heightened loss of these cells promotes fibroblast activation and remodeling. Changes in glutathione redox status have been reported in IPF patients. S-glutathionylation, the conjugation of glutathione to reactive cysteines, is catalyzed in part by glutathione-S-transferase π (GSTP). To date, no published information exists linking GSTP and IPF to our knowledge. We hypothesized that GSTP mediates lung fibrogenesis in part through FAS S-glutathionylation, a critical event in epithelial cell apoptosis. Our results demonstrate that GSTP immunoreactivity is increased in the lungs of IPF patients, notably within type II epithelial cells. The FAS-GSTP interaction was also increased in IPF lungs. Bleomycin- and AdTGFβ-induced increases in collagen content, α-SMA, FAS S-glutathionylation, and total protein S-glutathionylation were strongly attenuated in Gstp–/– mice. Oropharyngeal administration of the GSTP inhibitor, TLK117, at a time when fibrosis was already apparent, attenuated bleomycin- and AdTGFβ-induced remodeling, α-SMA, caspase activation, FAS S-glutathionylation, and total protein S-glutathionylation. GSTP is an important driver of protein S-glutathionylation and lung fibrosis, and GSTP inhibition via the airways may be a novel therapeutic strategy for the treatment of IPF.

Authors

David H. McMillan, Jos L.J. van der Velden, Karolyn G. Lahue, Xi Qian, Robert W. Schneider, Martina S. Iberg, James D. Nolin, Sarah Abdalla, Dylan T. Casey, Kenneth D. Tew, Danyelle M. Townsend, Colin J. Henderson, C. Roland Wolf, Kelly J. Butnor, Douglas J. Taatjes, Ralph C. Budd, Charles G. Irvin, Albert van der Vliet, Stevenson Flemer, Vikas Anathy, Yvonne M.W. Janssen-Heininger

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Figure 3

GSTP deficiency attenuates bleomycin- and AdTGFβ-induced protein S-glutathionylation.

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GSTP deficiency attenuates bleomycin- and AdTGFβ-induced protein S-gluta...
Wild-type and Gstp–/– mice were treated with either bleomycin for 15 days or AdTGFβ for 21 days as indicated. (A and B) Detection of total PSSG content in mouse lung homogenates with a modified DTNB assay. Shown are pooled data from 2 independent experiments. *P < 0.05 relative to PBS or AdCtrl group, †P < 0.05 relative to respective wild-type group by 2-way ANOVA with a Tukey post-test (n = 4–11 per group). (C and D) Assessment of FAS-SSG content by immunoprecipitation of total PSSG and Western blot for FAS. Statistically significant differences between wild-type and Gstp–/– groups treated with either (C) bleomycin or (D) AdTGFβ were determined by densitometric analysis. *P < 0.05 by unpaired Student’s t test (n = 3 per group). The data shown in C and D are representative of 1 of 2 independent experiments. GSTP, glutathione-S-transferase π; FAS-SSG, S-glutathionylated FAS; AdCtrl, control adenovirus; AdTGFβ, recombinant adenovirus expressing active TGF-β1; GSH, glutathione; DTT, dithiothreitol; WB, Western blot.