Effects of Fine Particulate Matter (PM2.5) in Cultured Human Vocal Fold Fibroblasts

Human exposures to fine particulate matter (PM2.5), a major air pollutant generated by multiple anthropogenic sources, are increasing worldwide. Though its adverse impacts on the lower airway are well-researched, PM2.5 has poorly understood effects on the upper airway. Our previous clinical research revealed increased dysphonia in the setting of elevated PM2.5 levels, though underlying interactions between PM2.5 and the vocal folds are unclear. This study evaluated the effects of PM2.5 on cultured human vocal fold fibroblasts (hVFFs), the primary cell type of the lamina propria.

Cultured hVFFs were exposed to increasing concentrations of PM2.5; unexposed cells served as control. After 24-72 h, cell morphology, cell viability, oxidative stress, and extracellular matrix and inflammatory gene expression were examined. Multivariate models estimated the association of PM2.5 concentration and cell viability.

Morphologic analysis revealed persistent PM2.5 particles associated with hVFFs post-exposure, signifying extracellular adherence and/or intracellular migration. Increasing concentrations of PM2.5 induced elevated cytotoxicity and oxidative stress. Extracellular matrix and inflammatory gene expression were unaffected by exposure concentration or duration.

Our findings provide an in vitro methodology for studying hVFF responses to PM2.5. In revealing the persistent cellular association of PM2.5 particles following exposures, as well as dose-dependent decreased cell viability and increased oxidative stress at higher PM2.5 concentrations, this work provides key initial insights into the effects of PM2.5 on hVFF. Findings from this work will provide a foundation for future in vitro and mechanistic studies of the cell-level effects of air pollution on the vocal folds.

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