Azithromycin attenuates myofibroblast differentiation and lung fibrosis development through proteasomal degradation of NOX4

Kazuya Tsubouchi, Jun Araya, Shunsuke Minagawa, Hiromichi Hara, Akihiro Ichikawa, Nayuta Saito, Tsukasa Kadota, Nahoko Sato, Masahiro Yoshida, Yusuke Kurita, Kenji Kobayashi, Saburo Ito, Yu Fujita, Hirofumi Utsumi, Haruhiko Yanagisawa, Mitsuo Hashimoto, Hiroshi Wakui, Yutaka Yoshii, Takeo Ishikawa, Takanori NumataYumi Kaneko, Hisatoshi Asano, Makoto Yamashita, Makoto Odaka, Toshiaki Morikawa, Katsutoshi Nakayama, Yoichi Nakanishi, Kazuyoshi Kuwano

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

Accumulation of profibrotic myofibroblasts is involved in the process of fibrosis development during idiopathic pulmonary fibrosis (IPF) pathogenesis. TGFB (transforming growth factor β) is one of the major profibrotic cytokines for myofibroblast differentiation and NOX4 (NADPH oxidase 4) has an essential role in TGFB-mediated cell signaling. Azithromycin (AZM), a second-generation antibacterial macrolide, has a pleiotropic effect on cellular processes including proteostasis. Hence, we hypothesized that AZM may regulate NOX4 levels by modulating proteostasis machineries, resulting in inhibition of TGFB-associated lung fibrosis development. Human lung fibroblasts (LF) were used to evaluate TGFB-induced myofibroblast differentiation. With respect to NOX4 regulation via proteostasis, assays for macroautophagy/autophagy, the unfolded protein response (UPR), and proteasome activity were performed. The potential anti-fibrotic property of AZM was examined by using bleomycin (BLM)-induced lung fibrosis mouse models. TGFB-induced NOX4 and myofibroblast differentiation were clearly inhibited by AZM treatment in LF. AZM-mediated NOX4 reduction was restored by treatment with MG132, a proteasome inhibitor. AZM inhibited autophagy and enhanced the UPR. Autophagy inhibition by AZM was linked to ubiquitination of NOX4 via increased protein levels of STUB1 (STIP1 homology and U-box containing protein 1), an E3 ubiquitin ligase. An increased UPR by AZM was associated with enhanced proteasome activity. AZM suppressed lung fibrosis development induced by BLM with concomitantly reduced NOX4 protein levels and enhanced proteasome activation. These results suggest that AZM suppresses NOX4 by promoting proteasomal degradation, resulting in inhibition of TGFB-induced myofibroblast differentiation and lung fibrosis development. AZM may be a candidate for the treatment of the fibrotic lung disease IPF.

Original languageEnglish
Pages (from-to)1420-1434
Number of pages15
JournalAutophagy
Volume13
Issue number8
DOIs
Publication statusPublished - Aug 3 2017

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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