Thyroid hormone (TH) is critical for the maintenance of cellular homeostasis during stress responses, but its role in lung fibrosis is unknown. Here we found that the activity and expression of iodothyronine deiodinase 2 (DIO2), an enzyme that activates TH, were higher in lungs from patients with idiopathic pulmonary fibrosis than in control individuals and were correlated with disease severity. We also found that Dio2-knockout mice exhibited enhanced bleomycin-induced lung fibrosis. Aerosolized TH delivery increased survival and resolved fibrosis in two models of pulmonary fibrosis in mice (intratracheal bleomycin and inducible TGF-β1). Sobetirome, a TH mimetic, also blunted bleomycin-induced lung fibrosis. After bleomycin-induced injury, TH promoted mitochondrial biogenesis, improved mitochondrial bioenergetics and attenuated mitochondria-regulated apoptosis in alveolar epithelial cells both in vivo and in vitro. TH did not blunt fibrosis in Ppargc1a- or Pink1-knockout mice, suggesting dependence on these pathways. We conclude that the antifibrotic properties of TH are associated with protection of alveolar epithelial cells and restoration of mitochondrial function and that TH may thus represent a potential therapy for pulmonary fibrosis.

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The work was in part supported by US National Institutes of Health (NIH) grants R01HL095397, R01HL127349 (N.K.), R01HL1109233, R01HL125250 (E.L.H.), RO1DK65055 (A.C.B.) and RO1DK52798 (T.S.S.), the Flight Attendant Medical Research Institute (P.J.L.), American Lung Association Award RT 350419, Marie Sklodowska/Curie ERS/EU-RESPIRE 2-8860-2015 grant (A.T.), American Lung Association Award RG-415350 (A.S.) and Pulmonary Fibrosis Foundation (PPF) Albert Rose Established Investigator Award 415245 (G.Y.).

Author information

Author notes

    • Rong Wang

    Present address: Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministries of Education and Health, and State and Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, China.

    • Guoying Yu
    •  & Argyris Tzouvelekis

    These authors contributed equally to this work.


  1. Section of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA.

    • Guoying Yu
    • , Argyris Tzouvelekis
    • , Rong Wang
    • , Jose D Herazo-Maya
    • , Gabriel H Ibarra
    • , Anup Srivastava
    • , Giuseppe DeIuliis
    • , Farida Ahangari
    • , Tony Woolard
    • , Nachelle Aurelien
    • , Ye Gan
    • , Praveen Mannam
    • , Patty J Lee
    • , Erica L Herzog
    •  & Naftali Kaminski
  2. Division of Immunology, Biomedical Sciences Research Center “Alexander Fleming”, Athens, Greece.

    • Argyris Tzouvelekis
  3. Division of Endocrinology/Metabolism, Rush University Medical Center, Chicago, Illinois, USA.

    • Joao Pedro Werneck de Castro
    •  & Antonio C Bianco
  4. Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.

    • Joao Pedro Werneck de Castro
  5. The Salk Institute for Biological Studies, Molecular and Cell Biology Laboratory, La Jolla, California, USA.

    • Rafael Arrojo e Drigo
  6. CCMI Electron Microscopy Core Facility, Yale University School of Medicine, New Haven, Connecticut, USA.

    • Morven Graham
    •  & Xinran Liu
  7. Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA.

    • Robert J Homer
  8. Pathology and Laboratory Medicine Service, VA Connecticut HealthCare System, West Haven, Connecticut, USA.

    • Robert J Homer
  9. Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA.

    • Thomas S Scanlan


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G.Y. and A.T. performed most of the experiments with the assistance of R.W., J.D.H.-M., J.P.W.d.C., R.A.e.D., F.A., G.D., N.A., T.W., J.D., Y.G., R.D., G.H.I. and A.C.B. A.S. and P.M. performed the mitochondrial function experiments. M.G. and X.L. performed the electron microscopy experiments and analysis. G.Y., A.T. and N.K. performed the histological analyses with R.J.H. T.S.S. and G.H.I. assisted on the GC-1 animal experiments. G.Y., A.T. and N.K. conceived the project, designed the experiments, and analyzed and interpreted the results. A.T., G.Y. and N.K. drafted and revised the manuscript. E.L.H., P.J.L. and A.C.B. interpreted results and revised the manuscript.

Competing interests

A.T., G.Y. and N.K. are inventors on a pending patent with the US Patent and Trademark Office on use of thyroid hormone as an antifibrotic agent entitled “Novel methods of treating or preventing fibrotic lung diseases,” OCR 6368-047162-7029P1 (00219). N.K. consulted for Biogen Idec, Boehringer Ingelheim, Numedii, MMI and Pliant and has an ongoing collaboration with MiRagen, all outside the subject matter of the submitted work. E.L.H. consulted for Boehringer Ingelheim and held grant funding from Sanofi and Promedior, all outside the subject matter of the submitted work. All other authors declare no competing interests.

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