Effects of exposure to aluminum oxide (AL2O3) and cerium oxide (CeO2) nanoparticles on human alveolar Cells in vitro

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Valerie Joy Fricault (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
Ramji Bhandari

Abstract: Manufactured aluminum oxide and cerium oxide nanoparticles are regularly released into the environment, yet there are presently no regulations to monitor their non-acute effects on respiratory health. The present study, therefore, examined effects of aluminum oxide (AL2O3) and cerium oxide (CeO2) nanoparticles on human alveolar cells in vitro. ATCC A549 human alveolar carcinoma cells were exposed to two different concentrations of these two different nanoparticles to test for cellular and molecular phenotypes, particularly cell viability, oxidative stress, disease marker gene expression and epigenetic responses. Samples were collected at 22 and 88 hours of incubation with and without nanoparticles, representing cells grown to one and four population doublings. Viability and cell health were measured using flow cell cytometry, a fluorescent alamarBlue® assay and total SOD assay. DNA and RNA were extracted from multiple cell samples at 22 and 88 hours of exposure. The extracted DNA was used to assess global DNA methylation and RNA was converted to cDNA to quantify gene expression. The mRNA levels of 15 genes, which are known to transcribe immunological and epigenetic traits, were measured by quantitative realtime PCR. The immunological genes assayed were SOD, SESN, iNOS, IL-6, IL-33, HLA-B, IRF8, CD44 and TNFa. The epigenetic marker genes assayed were DNMT1, DNMT3A, EZH1, KMT2D, EHMT1 and DOT1. Neither of the nanoparticle types nor concentrations affected viability of A549 cells, yet every experimental condition had effects on one or more gene transcript levels. The low concentration Al2O3 showed a decrease in global DNA methylation in 22 hours, while the high concentration showed an increase in 88 hours. DNMT1 expression increased with exposure to AL2O3 with the high concentration in 22 hours suggesting an increased maintenance of genome DNA methylation during the first doubling of cells due to exposure. Conversly, two conditions of AL2O3 exposure caused a decrease in DNMT3A, the de novo methylator. Histone methylation gene DOT1L decreased in the Low 88 group. Pro-inflammatory HLA-B transcripts increased in the High group in 88 hours. ROS reducing SESN3 transcript levels decreased within 22 hours incubation. Cells exposed to varying concentrations of CeO2 nanoparticles showed a tendency to increase both DNMT1 and DNMT3A transcript levels as well as HLA-B and asthma exacerbation indicator IL-6. Similar to the response of AL2O3 exposed cells, there was a decrease in DOT1L expression and SESN3 expression in CeO2 exposed cells, suggesting that both Al2O3 and CeO2 nanoparticles induce epigenetic modifications at various levels of biological organization. The present study, therefore, suggests that these nanoparticle exposures can lead to increased oxidative stress, activation of cancer and asthma related genes, and epigenetic alterations without affecting the viability of A549 alveolar cells. [This abstract has been edited to remove characters that will not display in this system. Please see the PDF for the full abstract.]

Additional Information

Language: English
Date: 2018
A549, Al2O3, CeO2, Epigenetic, Nanoparticles
Aluminum oxide $x Physiological effect
Cerium oxides $x Physiological effect

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