Thioredoxin-1 suppresses lung injury and apoptosis induced by diesel exhaust particles (DEP) by scavenging reactive oxygen species and by inhibiting DEP-induced downregulation of Akt.
Diesel exhaust particles (DEP) are reactive oxygen species (ROS)-inducing toxic agents that damage lungs. Thioredoxin-1 (Trx-1) is a thiol protein with antioxidant and redox-regulating effects. In this study, we demonstrate that Trx-1 scavenges ROS generated by DEP and attenuates the lung injury. Intratracheal instillation of DEP resulted in the generation of more hydroxyl radicals in control mice than in human Trx-1 (hTrx-1)-transgenic mice as measured by noninvasive L-band in vivo electron spin resonance. DEP caused acute lung damage with massive infiltration of inflammatory cells in control mice, but much less damage in hTrx-1-transgenic mice. The hTrx-1 transgene protected the mice against DEP toxicity. To investigate further the molecular mechanism of the protective role of Trx-1 against DEP-induced lung injury, we used hTrx-1-transfected L-929 cells and recombinant hTrx-1 (rhTrx-1)-pretreated A-549 cells. DEP-induced ROS generation was suppressed by hTrx-1 transfection or pretreatment with rhTrx-1. Endogenous Trx-1 expression was induced by DEP in control cells. The downregulation of Akt phosphorylation by DEP resulted in apoptosis, which was prevented by Trx-1. Moreover, an Akt inhibitor canceled this protective effect of Trx-1. Collectively, the results suggest that Trx-1 exerts antioxidant effects in vivo and in vitro and that this plays a role in protection against DEP-induced lung damage by regulating Akt-mediated antiapoptotic signaling.
Kaimul Ahsan
M
M
Department of Biological Responses, Institute for Virus Research, Kyoto University, 53 Shogoin, Kawahara-cho, Sakyo, Kyoto 606-8507, Japan.
Nakamura
Hajime
H
Tanito
Masaki
M
Yamada
Kenichi
K
Utsumi
Hideo
H
Yodoi
Junji
J
D000818:Animals; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D015536:Down-Regulation; D005260:Female; D016166:Free Radical Scavengers / Q000378:metabolism / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000473:pathology; D008171:Lung Diseases / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010316:Particle Size; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D001335:Vehicle Emissions / Q000633:toxicity*
D000975:Antioxidants; D016166:Free Radical Scavengers; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D001335:Vehicle Emissions; D017665:Hydroxyl Radical; D013879:Thioredoxins; D051057:Proto-Oncogene Proteins c-akt