Repeated Polystyrene Nanoplastic Exposure Alters the Redox Balance and Inflammatory Signaling in the Lymphatic Endothelial Cells

Environmental exposure to nanoplastics (NPLs) is an emerging concern for human health, yet their effects on lymphatic endothelium remain poorly understood. We investigated the effects induced by repeated exposure of the murine lymph node endothelial cells (SVEC4-10 cell line) to polystyrene NPLs (PS-NPLs) at 1.6, 16, and 160 μg/mL over 15 days. PS-NPLs have been characterized in terms of hydrodynamic diameter and polydispersity by dynamic light scattering. Cell viability remained unchanged, while repeated exposure induced a pronounced oxidative stress response, characterized by increased reactive oxygen species (ROS), protein and lipid oxidation, and depletion of reduced glutathione. Nitric oxide levels increased modestly (22.8–30.6%) at the highest concentration. Inflammatory responses were temporally regulated, with early increases in TNFα and IL-1β levels, followed by partial normalization, whereas IL-6 expression showed delayed elevation. Hsp27, Hsp60, Hsp70, and Hsp90 expressions displayed changes consistent with activation of cellular stress-response pathways. Overall, repeated PS-NPL exposure induced a dynamic oxidative stress response and temporally regulated inflammatory alterations, without a significant decrease in cell viability. The temporal modulation of these responses may reflect compensatory cellular processes during prolonged exposure, although the specific mechanisms underlying this response remain to be established.