Secretion Proteome Profiling of Airway Epithelial Cultures Exposed to Burn Pit Smoke Condensates Reveals Combustion Type Specific Toxicity Patterns and Cellular Damage
On this page:
Rationale: Due to waste management restrictions in military operation areas, burn pits are a regularly employed way to eliminate waste in these zones. Since such open burn pits emit many toxic chemicals and are often located in proximity to military bases, there is major concern for the airway health of military personnel. In fact, many veterans that served overseas report health issues that are associated with the inhalation of smoke during their military service. In this study we employed an in vitro approach to investigate the airway epithelial surface effects of burn pit smoke emissions of the common fuel materials plastic and cardboard under two burning temperature conditions and analyzed the secretion proteome profiles of these burn pit exposures to evaluate toxicity patterns and to correlate chemical harm signatures.
Fig. SEQ Figure \* ARABIC 1: Schematic of the experimental strategy to investigate the proteomic toxicity patterns of Burn Pit fuel smoke condensates on the human airway epithelium.
Methods: Primary human bronchial epithelial (HBE) cultures from six different donors were exposed to condensates of flaming and smoldering temperature combusted plastic or cardboard, in 5 or 25 µg/ml concentrations every 24 hours, and secretions were collected after the 3rd exposure day. Material combustion was performed using an automated furnace system under controlled conditions, and chemical composition was determined by gas chromatography-mass (GC-MS). Label-free liquid chromatography tandem mass spectrometry (LC-MS/MS) was used for quantitative secretion proteomics.
Results: The apical HBE secretion proteome analysis identified ~2100 total proteins of which ~600 proteins displayed significantly increased levels post flaming condensate exposures, regardless of the burn pit fuel material. Further, 5 µg/ml condensate exposed cultures displayed significantly higher numbers of proteins with elevated levels (~600) compared to 25 µg/ml condensate exposed cultures (~100). Among the significantly increased proteins were markers of cellular toxicity and airway epithelial cell integrity loss (e.g., LDH, GAPDH or G6PD). Comparatively, few proteins showed significant reductions in their apical secretion abundance, among them the mucins MUC5B and MUC4, as well as the protease inhibitor SLPI.
Conclusions: Our study, utilizing primary human bronchial
epithelial cultures to investigate the airway surface proteome changes induced
by burn pit smoke condensates shows a significant toxicity effect on the
composition of the airway epithelial secretome. Our results further indicate
and support observations that the type of combustion (flaming) seems to play a
more significant role in the toxicity outcome than the burn material. Notably,
our data shows considerable airway epithelial cell damage by a large number of
leaking intracellular proteins, and a reduction of major secreted innate
defense proteins, which may hint at the airway health risks associated with the
exposure to burn pit smoke at military bases. [This abstract does not reflect
EPA