Oxygen is supplied as a supportive treatment for patients suffering from acute respiratory distress syndrome. Unfortunately, high oxygen concentration increases reactive oxygen species generation, which causes DNA damage and ultimately cell death in the lung. Although 8-oxoguanine-DNA glycosylase (OGG-1) is involved in repairing hyperoxia-mediated DNA damage, the underlying molecular mechanism remains elusive. In this study, we report that ogg-1–deficient mice exhibited a significant increase of proinflammatory cytokines (TNF-α, IL-6, and IFN-γ) in the lung after being exposed to 95% oxygen. In addition, we found that ogg-1 deficiency downregulated (macro)autophagy when exposed to hyperoxia both in vitro and in vivo, which was evident by decreased conversion of LC3-I to LC3-II, reduced LC3 punctate staining, and lower Atg7 expression compared with controls. Using a chromatin immunoprecipitation assay, we found that OGG-1 associated with the promoter of Atg7, suggesting a role for OGG1 in regulation of Atg7 activity. Knocking down OGG-1 decreased the luciferase reporter activity of Atg7. Further, inflammatory cytokine levels in murine lung epithelial cell line cells were downregulated following autophagy induction by starvation and rapamycin treatment, and upregulated when autophagy was blocked using 3-methyladenine and chloroquine. atg7 knockout mice and Atg7 small interfering RNA-treated cells exhibited elevated levels of phospho–NF-κB and intensified inflammatory cytokines, suggesting that Atg7 impacts inflammatory responses to hyperoxia. These findings demonstrate that OGG-1 negatively regulates inflammatory cytokine release by coordinating molecular interaction with the autophagic pathway in hyperoxia-induced lung injury.
This work was supported by Flight Attendant Medical Research Institute Grant 103007 and National Institutes of Health (NIH) Grants AI101973-01, AI109317-01A1, and AI097532-01A1 (to M.W.). The University of North Dakota Core Facilities were supported by NIH Institutional Development Award Networks of Biomedical Research Excellence Grant P20GM103442 and NIH Centers of Biomedical Research Excellence Grants P30GM103329 and P20GM113123.
The online version of this article contains supplemental material.
Abbreviations used in this article:
- autophagy-related gene
- bronchoalveolar lavage
- chromatin immunoprecipitation
- confocal laser scanning microscopy
- murine alveolar macrophage cell line
- murine lung epithelial cell line
- 8-oxoguanine-DNA glycosylase
- polymorphonuclear neutrophil
- quantitative real-time PCR
- reactive oxygen species
- small interfering RNA
- wild type.
- Received June 9, 2016.
- Accepted January 23, 2017.
- Copyright © 2017 by The American Association of Immunologists, Inc.