Effect of Combustion Particle Morphology on Biological Responses in a Co-culture of Human Lung Epithelial and Macrophage-Like Cells
KAMALJEET KAUR, Raziye Mohammadpour, Hamid Ghandehari, Chris Reilly, Robert Paine, Kerry Kelly,
University of Utah Abstract Number: 190
Working Group: Health-Related Aerosols
AbstractAtmospheric aging of combustion particles alter their chemical properties and morphology from a fiber-like to more compact and spherical. Previous studies of fresh and aged combustion particles have suggested that the changing chemical composition is the prime cause of the observed differences in toxicological response. However, little is known about the contribution of morphological changes in atmospherically aged particles to their toxicological response, possibly due to the difficulty in resolving the two properties (composition and morphology) that change simultaneously. A method to change particle morphology without the need to change chemical composition would help elucidate the effect of this morphological change on cellular responses. This study altered the shape of lab-generated combustion particles from fiber-like to a more compact spherical shape using water condensation and evaporation. Quantitative comparison of polycyclic aromatic hydrocarbons and semi-volatiles for both shapes (altered and not-altered) confirmed no significant change in composition. Using an electrostatic field-based air-liquid exposure (ALI) chamber, the two shapes were exposed to a co-culture of human airway epithelial (A549) and differentiated human monocyte (THP-1) cells. For the same mass dose of 2 µg/cm
2, both shapes were ingested by cells, induced a pro-inflammatory response (IL-8 and TNFα) and enhanced CYP1A1 gene expression compared to air controls. The more compact spherical particles (representative of atmospherically aged combustion particles) induced more early apoptosis and release of TNFα compared to the more fiber-like particles. The result suggests a contribution of morphology to the increased toxicity of aged particles.