Characterization of extracellular vesicles from primary skin epithelial cells and cell lines from Atlantic salmon

Extracellular vesicle (EV) research in fish, particularly in aquaculture-relevant species, is gaining momentum, with interest in biomarker development, while the availability of in vitro tools to study EV-mediated cellular communication in fish is limited, particularly with respect to primary cell lines. As salmon represents one of the most valuable fish species in global aquaculture, identifying robust biomarkers for fish health monitoring is a high priority. This study introduces a novel in vitro model for EV research in salmon, utilising primary and immune relevant cell lines to closely mimic in vivo conditions. EVs were profiled from primary scale derived keratocyte cells (SKC), in addition to EVs from previously established salmon cell lines (ASK and SSP-9 from salmon head kidney). EV size profiles were identified overall in the 50-450 nm range, with some differences between the cell lines. EV protein cargoes were analyzed by LC-MS/MS alongside associated pathway enrichment, providing insights for roles of EVs in cell-type-specific communication, including immune responses. Notably, the SKC-derived EVs revealed proteins and pathways associated with wound healing, keratinization, and immune defense, highlighting their potential as therapeutic targets. Additionally, shared pathways identified in EVs from all cell lines, included the non-canonical NF-κB pathway and ubiquitination, offering new perspectives into EV-mediated signaling in fish. Our in-vitro model system may provide a translational platform to develope EVs as robust biomarkers of fish health, with potential applications in aquaculture.