Lung recovery from graphene oxide induced DNA damage is dependent on size, dose and inflammation profile

Abstract BackgroundA key aspect of any new material safety assessment is the evaluation of their in vivo genotoxicity. Graphene oxide (GO) has been studied for many promising applications, but there are remaining concerns about its safety profile, especially after inhalation. Herein we tested whether GO lateral dimension, comparing micrometric (LGO) and nanometric (USGO) GO sheets, could have an impact on the formation of DNA double strand breaks in mouse lungs. We used spatial resolution and differential cell type analysis to decipher between DNA damages on epithelial and immune cells. Single as well as multiple lung exposures were performed to evaluate the importance of using more realistic scenario when evaluating the potential genotoxicity of materials.ResultsDNA damages induced by GO were size and dose dependent, in both single and repeated exposure scenario. A fast recovery was found after single exposure, irrespective of the dimensions of the GO sheets. However, the LGO induced long-term DNA damages in lung alveolar epithelia, at 84 days after repeated exposure. A multiparametric correlation analysis of repeated exposure data revealed that transient or persistent inflammation and oxidative stress were associated to either recovery or persistent DNA damages. For USGO, recovery from DNA damages was correlated to efficient recovery from acute inflammation. In contrast, the persistence of LGO in the lungs and the long-lasting presence of multinucleated macrophages were associated to persistent DNA damages. Conclusions Overall these results highlight the importance of the exposure scenario used. We showed that LGO was more genotoxic after repeated exposure than single exposure due to persistent lung inflammation. These findings are important in the context of human health risk assessment and toward establishing recommendations for a safe use of graphene based materials in the workplace.