299 A CTS team approach to assess the in vitro toxicity of microplastic fibers to human lung epithelial cells cultured at an air-liquid interface

OBJECTIVES/GOALS: Our goal is to determine whether microplastic fibers (MPFs) provide signals for dendritic cell-induced Th2 polarization via epithelial-cell-derived thymic stromal lymphopoietin (TSLP). We seek to highlight a potential mechanism for MPF-induced airway toxicity associated with asthma exacerbation. METHODS/STUDY POPULATION: Primary human bronchial epithelial cells (NHBEs) were grown and differentiated at an air-liquid interface. Dyed and undyed polyester MPFs (14x45 µm) generated using a cryomicrotome were delivered to NHBEs through a custom designed mesh-hopper system. After the exposure period (6, 12, 24 hrs), cell viability was assessed using alamarBlue, and RT-qPCR was performed to determine mRNA expression of asthma associated genes (i.e., TSLP, IL-13, IL-33, etc.,) in NHBEs. Bulk mRNA-sequencing followed by bioinformatics will be performed to observe other plausible pathways tweaked by lung cell exposure to MPFs. RESULTS/ANTICIPATED RESULTS: Through gravimetric analysis, it was determined that the mesh-hopper system can achieve delivery efficiencies of at least 85% for as low as 500 fibers. Following exposure, results show polyester MPFs (500 - 1,000 fibers) exposed to NHBEs at multiple time points (6, 12, 24 hrs) did not result in a statistically significant decrease in cell viability. Treatment with 500 undyed MPFs resulted in a slight increase in TSLP expression at 6 hrs that decreased over time, whereas all other treatment groups resulted in TSLP downregulation. Similarly, 500 undyed MPFs resulted in an increase in IL-13 expression at both 6 and 12 hrs with all other treatment groups leading to IL-13 downregulation. We anticipate the RNA-seq results will show pro-inflammatory pathways are highly targeted following NHBE exposure to MPFs. DISCUSSION/SIGNIFICANCE: This study is one of the first to mechanistically assess the impact of MPFs on lung cells while simultaneously addressing the need for a reliable system that delivers MPFs to ALI cultures to better mimic inhalation and avoid inadequate resuspension of particles in liquid medium.