Macrophage Cytotoxicity and Global DNA Methylation Following Carbon Fiber Dust Exposure
Additional Funding Sources
The Bridges to Baccalaureate program is supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award No. R25GM123927.
Abstract
Carbon fiber composite materials are used in a wide variety of industries including automobile, golf, and archery applications. Modification of carbon materials by cutting or machining can generate particulate matter which represents a potential occupational health risk. While the pulmonary health effects of carbon nanotubes (1-10nm) and carbon nanofibers (100-1000nm) have been well studied, the toxicity of carbon fibers (1-10um) has not been well characterized. Here, we evaluate the biophysical properties and cytotoxic potential of carbon fibers generated during arrow cutting. An initial determination of carbon fiber size and shape was accomplished using FESEM. The fibers had mean width of 7.21um (SD=0.93) and mean length of 33.99um (SD=8.95). Then, we demonstrated dose-dependent cellular toxicity in mouse RAW264.7 macrophages using a CellTiter-Blue assay and contextualized this with data generated from asbestos exposure (a similarly sized and shaped toxicant). Further, we explored a potential mechanism that might explain this cytotoxicity using bisulfite pyrosequencing to measure DNA methylation in repetitive elements. Carbon fiber exposed mouse macrophages did not demonstrate differential DNA methylation at LINE1 or IAP repetitive elements compared to untreated controls. Future directions for this work include examination of other epigenetic regions of interest for DNA methylation differences, interrogation of cell signaling cascades that could result in cell death, and additional in vitro exposures using human-derived cells or primary cultured cells.
Macrophage Cytotoxicity and Global DNA Methylation Following Carbon Fiber Dust Exposure
Carbon fiber composite materials are used in a wide variety of industries including automobile, golf, and archery applications. Modification of carbon materials by cutting or machining can generate particulate matter which represents a potential occupational health risk. While the pulmonary health effects of carbon nanotubes (1-10nm) and carbon nanofibers (100-1000nm) have been well studied, the toxicity of carbon fibers (1-10um) has not been well characterized. Here, we evaluate the biophysical properties and cytotoxic potential of carbon fibers generated during arrow cutting. An initial determination of carbon fiber size and shape was accomplished using FESEM. The fibers had mean width of 7.21um (SD=0.93) and mean length of 33.99um (SD=8.95). Then, we demonstrated dose-dependent cellular toxicity in mouse RAW264.7 macrophages using a CellTiter-Blue assay and contextualized this with data generated from asbestos exposure (a similarly sized and shaped toxicant). Further, we explored a potential mechanism that might explain this cytotoxicity using bisulfite pyrosequencing to measure DNA methylation in repetitive elements. Carbon fiber exposed mouse macrophages did not demonstrate differential DNA methylation at LINE1 or IAP repetitive elements compared to untreated controls. Future directions for this work include examination of other epigenetic regions of interest for DNA methylation differences, interrogation of cell signaling cascades that could result in cell death, and additional in vitro exposures using human-derived cells or primary cultured cells.