Exploring Seasonal Dynamics of Sea Spray Aerosol Bioactivity: Insights into Molecular Effects on Human Bronchial Epithelial Cells

Sea spray aerosol (SSA) is a complex mixture of natural substances that can be inhaled by coastal residents. Previous studies have suggested that SSA may have positive effects on human health, but the molecular mechanisms and the factors influencing these effects are poorly understood. In this study, we exposed human bronchial epithelial cells (BEAS-2B) to natural SSA samples collected throughout a one-year period at the Ostend coast, Belgium, and measured cellular gene expression changes using RNA sequencing. We found that SSA exposure influenced the expression of genes involved in critical signaling pathways such as mTOR, PI3K, Akt, NF-kB, and AMPK, which are implicated in cancer, inflammation, and metabolic diseases. The number and direction of differentially expressed genes (DEGs) varied depending on the SSA sampling time and correlated with the phytoplankton density and chemical diversity of the SSA samples. Our results suggest that SSA contains bioactive compounds that may originate from marine algae and modulate cellular processes related to human health. We provide novel insights into the molecular effects of SSA exposure and highlight its potential as a source of natural therapeutics. To our knowledge, this is the first study to expose human lung cells to natural SSA at environmentally relevant, presenting a pioneering exploration of seasonal variations in exposure effects.