Extracellular vesicles of Anisakis simplex s. s. modulate inflammatory signaling and oxidative homeostasis in human...

Extracellular vesicles (EVs) released by parasitic helminths are increasingly recognized as key mediators of host-parasite communication; however, their functional impact on human intestinal epithelial cells remains poorly characterized. Here, we investigated the immunomodulatory and redox-related effects of EVs secreted by third-stage larvae of the zoonotic nematode Anisakis simplex s. s. on human Caco-2 intestinal epithelial cells. EVs after isolation were rigorously characterized by nanoparticle tracking analysis, transmission electron microscopy, and particle-to-protein ratio assessment. Exposure of Caco-2 cells to A. simplex EVs (Anis-EVs) resulted in a concentration-dependent reshaping of the epithelial immune profile, characterized by suppression of the pro-inflammatory chemokine IL-8 and enhanced secretion of the anti-inflammatory cytokines IL-10 and IL-13, while IL-4, IL-6, and IFN-γ levels remained largely unaffected. Anis-EVs also suppressed the secretion of the epithelial alarmins IL-33 and TSLP in a dose-dependent manner, representing the first evidence for Anis-EVs-mediated downregulation of these innate danger signals in an intestinal epithelial cell model. In parallel, Anis-EVs treatment significantly modulated cellular redox homeostasis. Anis-EVs-exposed cells displayed altered total antioxidant capacity and glutathione levels, increased superoxide dismutase activity, and reduced lipid peroxidation, indicating a finely tuned antioxidant response rather than overt oxidative damage. Together, these findings demonstrate that Anis-EVs act as multifunctional effectors that simultaneously attenuate inflammatory signaling, suppress epithelial alarmin release, and modulate oxidative stress pathways in human intestinal epithelial cells.