Effects of Laser Printer-Emitted Engineered Nanoparticles on Cytotoxicity, Chemokine Expression, Reactive Oxygen Species, DNA Methylation, and DNA Damage: A Comprehensive in Vitro Analysis in Human Small Airway Epithelial Cells, Macrophages, and Lymphoblasts.

Pirela SV1, Miousse IR, Lu X, Castranova V, Thomas T, Qian Y, Bello D, Kobzik L, Koturbash I, Demokritou P.

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Abstract

BACKGROUND:

Engineered nanomaterials (ENMs) incorporated into toner formulations of printing equipment become airborne during their consumer use. Although information on the complex physicochemical and toxicological properties of both toner powders and printer-emitted particles (PEPs) continues to grow, most toxicological studies have primarily used raw toner powders rather than the actual PEPs, which are not representative of current exposures experienced at the consumer level during printing.

OBJECTIVES:

To assess the biological responses of a panel of human cell lines to PEPs.

METHODS:

Three physiologically relevant cell lines-small airway epithelial cells (SAEC), macrophages (THP-1 cells) and lymphoblasts (TK6 cells)-were exposed to PEPs at a wide range of doses (0.5-100 μg/mL) that correspond to human inhalation exposure durations at the consumer level of ~ 8 hours and higher. Following treatment, toxicological parameters reflecting distinct mechanisms were evaluated.

RESULTS:

PEPs caused significant membrane integrity damage, an increase in reactive oxygen species (ROS) production as well as a rise in pro-inflammatory cytokine release in different cell lines at doses relevant to exposure durations from 7.8 to 1500 hours. Furthermore, there were differences in methylation patterns that although statistically insignificant, demonstrate the potential PEPs can have on the overall epigenome following exposure.

CONCLUSIONS:

The in vitro findings here suggest that laser printer-emitted engineered nanoparticles may be deleterious to lung cells, and provide preliminary evidence of epigenetic modifications that might translate to pulmonary disorders.