Gene Expression Changes in the Lung Following Exposure to Different Forms of Graphenes

Details

• Personal Author:
  Sager, Tina M. ; Eye, Tracy ; Barger, Mark W. ; Kodali, Vamsi K. ; Erdely, Aaron ; Boots, Theresa E. ; Roberts, Jennifer R.
• Description:
  Background and Purpose: Nanostructured materials display interesting and valuable properties. This has sparked a massive expansion in the production and use of engineered nanomaterials over the last 20 years. Due to this expansion, there is a need to assess the hazards of exposure to such materials to gain insight on their potential harm to human health. One of the newest and most highly utilized nanomaterials is graphene. Graphene has unique electrical and mechanical properties, a large specific surface area and potential biocompatibility. As a result, it is widely used in materials, electronics, energy, optics, and biomedical fields, for applications such as cell imaging, drug delivery and biosensing. Respiratory exposure in workers during the production and handling of graphene has been identified as the main concern for human exposure, but molecular mechanisms driving adverse outcomes in the lung related to exposure to different types of graphene remain to be determined. We previously characterized gene expression in lung tissue following in vivo exposure to graphene nanoplates of differing sizes. The goal of the study was to identify molecular changes in the lung associated with exposure to graphenes at different stages of oxidation and reduction. Methods: Three graphenes were provided by Cabot Corp. (Billerica, MA); graphene nanoplates approx. 5 µm lateral dimension (Gr5), graphene oxide (GO), and reduced graphene oxide (rGO). To assess gene expression changes in the lung initiated by these differing types of graphene, an in vivo acute bolus dose study was conducted. For this study, mice (male, C57BL/6J, approx. 8 weeks old) were dosed by oropharyngeal aspiration to these 3 graphenes (Gr5, GO, or rGO) or to multi-walled carbon nanotubes (MWCNT; Mitsui-7) at doses of 4 or 40 µg/mouse. At 4 h, 1 day, 7 days, 1 month, and 2 months post-exposure the left lung was ligated and frozen in liquid nitrogen for RNA isolation. Evaluation of gene expression was determined using the lung RNA and standard 96-well technology using the StepOne(TM) (Applied Biosystems, Carlsbad, CA, USA) with TaqMan® probes and primers. Assessed genes in the lung included IL-6, MIP-2 (Ccl2), MCP-1 (Cxcl2), MDC (Ccl22); all of which play a role in inflammation and macrophage activation; and osteopontin (Spp1) which is a gene indicative of tissue remodeling and possible granuloma and fibrosis formation. Relative gene expression was calculated using the comparative threshold method (2-ÄÄCt) with vehicle-treated mice serving as the reference group. Data from Taqman® arrays and qPCR were log transformed and analyzed by a Kruskal-Wallis Rank Sum Test with a Dunn's Test for pairwise comparison in R. Differences were considered statistically significant at p < 0.05. Results: The mRNA expression of genes encoding proinflammatory and tissue remodeling factors showed little to no change in the lungs of mice receiving the low dose of Gr5, GO, or rGO at any post-exposure timepoint. Increased mRNA expression of the proinflammatory genes in the lungs of the mice exposed to the high dose of Gr5 and GO was greatest at 4 hours post-exposure for IL-6, Cxcl2, Ccl2, and Ccl22. However, this expression declined by 7 days post-exposure and beyond. The expression of these genes persisted the longest in the high dose of rGO exposed mice. Beyond 1-day post-exposure (7-days, 1-month, and 2-months post-exposure) levels remained significantly elevated but did begin to decline, with the exception of Spp1. A similar pattern to rGO-exposed mice was also shown in mice exposed to a fibrogenic form of multiwalled carbon nanotube Conclusions: Taken together, the results suggest that all three types of these graphene nanoplates utilized in this study promote mRNA expression of genes involved in inflammation and tissue remodeling. However, effects resolved over time in Gr5- and GO-exposed mice; whereas alterations in gene expression were greatest in rGO-exposed mice and persisted throughout the study's time course. These study findings highlight property-dependent toxicological differences in materials within the graphene nanomaterial family. Description provided by NIOSH
• Subjects:
  • Graphite
  • Lung
  • Nanostructures
  • Occupational Health
  • Respiratory System
  • Safety
• Keywords:
  • Graphene; Nanomaterials; Gene expression; Lung tissue; In vivo studies; Toxicology; Molecular signaling
• Source:
  Toxicologist 2025 Mar; 204(S1):703
• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Chicago Region OSHA ; Ohio ; Philadelphia Region OSHA ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  2 pdf pages
• Volume:
  204
• NIOSHTIC Number:
  nn:20071592
• CAS Registry Number:
  • Graphite (CAS RN 7782-42-5)
• Federal Fiscal Year:
  2025
• NORA Priority Area:
  Manufacturing
• Peer Reviewed:
  False
• Download URL:
  https://stacks.cdc.gov/view/cdc/259367/cdc_259367_DS1.pdf
• File Type:
  [PDF - 261.13 KB]
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:0eac2ecf6c4c176d095413e751e6a93e9a2fb616d895bb73bedd7b5123c4f241525ca3be6e2d913ab353fe4dcd3cdac5e6598dfe7cdd84db87bb275b19df23bf