PNNL

Abstract

E-cigarette (e-cig) aerosols are complex mixtures of various chemicals including humectants (propylene glycol (PG) and vegetable glycerin (VG)), nicotine, and various flavoring additives. Emerging research is beginning to challenge the “relatively safe” perception of e-cigarettes. Recent studies suggest e-cig aerosols provoke oxidative stress however details of the underlying molecular mechanisms remain unclear. Here we used a redox proteomics assay of total thiol oxidation to identify signatures of site-specific protein thiol modifications in Sprague-Dawley rat lungs following in vivo e-cig aerosol exposures. Histologic evaluation of rat lungs exposed acutely to e-cig aerosols revealed mild perturbations in lung structure. Bronchoalveolar lavage (BAL) fluid analysis demonstrated no significant change in cell count or differential. Conversely, total lung glutathione decreased significantly in rats exposed to e-cig aerosol compared to air controls. Redox proteomics quantified 8507 oxidatively modified peptides representing 2865 proteins. Oxidative protein modifications and alterations by e-cig exposure induced perturbations of protein quality control, inflammatory responses and redox hemostasis. We validated perturbations of protein quality control with semi-quantification of total lung polyubiquitination and 20S proteasome activity. Our study highlights the importance of redox control in the pulmonary response to e-cig exposure and the utility of redox proteomics as a tool for elucidating the molecular mechanisms underlying this response.