Best Poster Presentation Award at Fourth Aerosol Dosimetry Meeting
Charbel Yazbeck, PhD’28, bioengineering, advised by BioE Associate Professor Jessica Oakes, was awarded the best student poster presentation at the Fourth Aerosol Dosimetry Meeting, for his poster titled “Modeling and Evaluating the Pulmonary Impacts of a Wildland Firefighting Career Through Equivalent Murine Exposure.”
Modeling and Evaluating the Pulmonary Impacts of a Wildland Firefighting Career Through Equivalent Murine Exposure
- Yazbeck1, M. Eden1, J. Matz1, M. Gollner2, C. Bellini1, J. M. Oakes1; 1Bioengineering, Northeastern University, Boston, MA, USA, 2 Mechanical Engineering, University of California, Berkeley, CA, USA.
Rationale: Wildland firefighters (WLFFs) are increasingly subjected to the unavoidable risks of wildfire smoke exposure as the frequency and severity of wildfires continue to rise. Concerns about occupational health hazards are significantly heightened, particularly as wildfire smoke particulates (PMs) are linked to a poorly understood decline in pulmonary function. In our study, we aim to investigate the underlying biomechanical impacts of an average 12-28 years WLFF career through an equivalent murine model.
Methods: We utilized a dosimetry model to determine an experimental protocol that matches the cumulative PM dose deposited in the lungs of WLLFs and apolipoprotein E-deficient (ApoE-/-) mice. The equivalency of 3 g of deposited PM mass in WLLFs after 7,200 work hours and 6 g after 14,400 work hours was established by exposing ApoE-/- mice to smoldering Douglas fir smoke (DFS) at an approximate PM concentration of 40 mg/m³ for 2 hours/day, 5 days/week, for 8 weeks, and 16 weeks, respectively. Following the prolonged exposure, the mice were intubated endotracheally and placed on a mechanical ventilator (flexiVent, SCIREQ) to measure pressure-volume (P-V) curves. We assessed changes in tissue morphology with histological staining, and pulmonary biomarkers with immunofluorescence.
Results: PMs in smoldering DFS were found to follow a unimodal lognormal distribution, with a count median diameter of 110 ± 20 nm and a geometric standard deviation of 1.47 ± 0.03. Consequently, after 16 weeks of DFS exposure the P-V curve shifted upward and leftward and static compliance was significantly higher compared to air controls, but hysteresis remained unchanged. This observation was supported by a significant increase in the thickness of the airway epithelium and alveolar septa, along with airspace enlargement. In addition, after 16 weeks of exposure, there was a significant decrease in the mean fluorescence intensity of the tight junction marker ZO-1 in the parenchyma, without a corresponding expression of ongoing epithelial-mesenchymal transition marker N-Cadherin. Extracellular matrix proteases, including neutrophil elastase and matrix metalloproteinase 9 and 12, exhibited a transient response.
Conclusion: The decline in lung functions observed in WLLFs could be attributed to damaged airways and degraded alveolar septa in response to inflammation, leading to emphysema.
Keywords: Occupational health, wildfire smoke inhalation, particulates, lung injury
Graphical abstract:
