Edirisinghe_2026_Dev.Comp.Immunol__105744

Extracellular vesicles (EVs) are nanoscale, lipid bilayer membrane-bound particles carry bioactive cellular cargos such as protein, lipids, nucleic acids. They are considered as key mediators of intercellular communication, potential biomarkers, and play role in numerous pathophysiological processes including modulating innate and adaptive immune responses. In this study, plasma-derived EVs were isolated from rainbow trout (Oncorhynchus mykiss) and determined the physicochemical-molecular properties to investigate their anti-inflammatory activities. Isolated EVs had inherent cup shaped morphology with an average particle diameter of 106.5 nm, and negative surface charge (zeta potential) of -24.2 mV. The purity of EVs was confirmed through immunoblot detection of EVs markers (ALIX, HSP90, HSP70, CD63, and TSG101), and highly enriched acetylcholinesterase (AChE). Transcriptional analysis demonstrated that EVs treatment up-regulated the Il-6 and Il-8 expression and down-regulation of Isg15, Isg20, Ifnbeta1, and Tnf-alpha expression and in RAW 264.7 cells. Moreover, flow cytometry results revealed EVs treated RAW 264.7 cells have decreased the reactive oxygen species (ROS) generation upon lipopolysaccharide (LPS)-induction. Enzyme-linked immunosorbent assay results evidenced that EVs role on the suppression of Inf-alpha and Ifn-beta, and induction of Il-6 proteins in LPS-induced RAW 264.7 cells. LPS-induced neuroinflammation was lowered through suppression of inflammatory (tnfalpha and il1beta) genes and inducing pro-inflammatory (il6 and il8) genes in EVs treated zebrafish brain. Thus, we suggest that plasma-derived EVs from rainbow trout have potential to regulate inflammatory and antioxidant responses and may serve as anti-inflammatory agent to mitigate cellular damage associated with inflammatory conditions.