Transient gene transfer and expression of Smad7 prevents bleomycin-induced lung fibrosis in mice
Atsuhito Nakao, … , Kohei Miyazono, Itsuo Iwamoto
Atsuhito Nakao, … , Kohei Miyazono, Itsuo Iwamoto
Published July 1, 1999
Citation Information: J Clin Invest. 1999;104(1):5-11. https://doi.org/10.1172/JCI6094.
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Article

Transient gene transfer and expression of Smad7 prevents bleomycin-induced lung fibrosis in mice

Abstract

TGF-β plays an important role in lung fibrosis, which is a major cause of suffering and death seen in pulmonary disease. Smad7 has been recently identified as an antagonist of TGF-β signaling. To investigate whether this novel molecule can be exploited for therapy of lung fibrosis, we determined the effect of exogenous Smad7, introduced by a recombinant human type 5 adenovirus vector, on bleomycin-induced lung fibrosis in mice. C57BL/6 mice with bleomycin-induced lungs received an intratracheal injection of a recombinant adenovirus carrying mice Smad7 cDNA. These mice demonstrated suppression of type I precollagen mRNA, reduced hydroxyproline content, and no morphological fibrotic responses in the lungs when compared with mice administered adenovirus carrying Smad6 cDNA. In addition, we found that expression of Smad7 transgene blocked Smad2 phosphorylation induced by bleomycin in mouse lungs. These data indicated that gene transfer of Smad7 (but not Smad6) prevented bleomycin-induced lung fibrosis, suggesting that Smad7 may have applicability in the treatment of pulmonary fibrosis.

Authors

Atsuhito Nakao, Makiko Fujii, Ryutaro Matsumura, Kotaro Kumano, Yasushi Saito, Kohei Miyazono, Itsuo Iwamoto

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Figure 1

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(a) Levels of immunoreactive Smad7 in the lungs of mice after treatment ...
(a) Levels of immunoreactive Smad7 in the lungs of mice after treatment with bleomycin plus AdCMV-Smad7. Expression of exogenous Smad6 or Smad7 derived from an AdCMV-Smad6 or AdCMV-Smad7 construct was detected in the lungs (lane 1: Smad6; lane 2: Smad7), peripheral blood cells (lane 3: Smad7), and spleen (lane 4: Smad7) of bleomycin-treated mice at day 7 by Western blotting using anti-FLAG antibody after infection of AdCMV-Smad6 or AdCMV-Smad7 at day 0. (b) Quantitative analysis of expression of Smad7 transgene in the lungs of mice after treatment with bleomycin plus AdCMV-Smad7. Expression of Smad7 transgene was detected by Western blotting as shown in a, and intensity of the bands of exogenous Smad7 detected at days 0, 2, 7, 14, and 21 was measured using NIH Image software. The relative intensity of the bands at indicated days was expressed as relative intensity compared with that at day 0. (c) Cellular localization of Smad7 transgene in the lungs of mice after treatment with bleomycin plus AdCMV-Smad7. Immunohistochemical staining using anti-FLAG antibody was performed as described in the text. Staining was observed mainly in the nucleus of alveolar epithelial cells and interstitial fibroblast-like cells (left), and bronchial epithelial cells (right).