Wildfire-relevant woodsmoke and extracellular vesicles (EVs): Alterations in EV proteomic signatures involved in extracellular matrix degradationand tissue injury in airway organotypic models
Wildfires adversely impact air quality and public health worldwide. Exposures to wildfire smoke are linked to adverse health outcomes, including cardiopulmonary diseases. Critical research gaps remain surrounding the underlying biological pathways leading to wildfire-induced health effects. The regulation of intercellular communication and downstream toxicity driven by extracellular vesicles (EVs) is an important, understudied biological mechanism. This study investigated EVs following a wildfire smoke-relevant in vitro exposure. We hypothesized that woodsmoke (WS) would alter the proteomic content of EVs secreted in organotypic in vitro airway models. Exposures were carried out using a tri-culture model of alveolar epithelial cells, fibroblasts, and endothelial cells and a simplified co-culture model of alveolar epithelial cells and fibroblasts to inform subsets of cell source-specific responses. Epithelial cells were exposed to WS condensate and EVs were isolated from basolateral conditioned medium following 24 h exposure. WS exposure did not influence EV particle characteristics and moderately increased EV count. 25 and 35 proteins were differentially loaded within EVs collected from the tri- and co-culture model, respectively, following WS exposure. EV proteins involved in extracellular matrix degradation and wound healing were consistently modulated across both models. However, distinct proteins involved in the wound healing pathway were altered between models, suggesting unique but concerted efforts across cell types to communicate in response to injury. These findings demonstrate that a wildfire-relevant exposure alters the EV proteome and suggest an impact on EV-mediated intercellular communication. Overall, they demonstrate the viability of organotypic approaches in evaluating EVs to investigate exposure-induced biomarkers and underlying mechanisms. They also highlight the impact of differences in the biological complexity of in vitro models used to evaluate the effects of inhaled toxicants.