Prenatal exposure to polystyrene nanoparticles induces neuroimmune dysregulation in the adult mouse brain

Microplastics have been detected in the brain, raising concerns regarding their neurological health impacts. However, the specific cellular targets and functional consequences of their accumulation remain understudied. This study explored the primary brain cell types that internalize polystyrene nanoparticles (PSNs) and investigated their immunological responses. Results showed that PSNs preferentially localized to primary microglia and astrocytes. Functional assays revealed divergent effects on lipopolysaccharide (LPS)-stimulated immune responses in the two cell types: PSNs potentiated LPS-induced activation of microglia, whereas they suppressed activation in astrocytes. Apoptotic responses were likewise cell-type specific, with PSN reducing apoptosis in microglia independently of LPS, but enhancing it in astrocytes. In vivo, adult mice exposed to both PSNs and LPS exhibited increased microglial numbers in the hippocampus compared to those receiving LPS alone. These findings demonstrate that PSNs disrupt the immune homeostasis of brain-resident glial cells through cell-type-specific mechanisms, highlighting a potential neurotoxic risk associated with nanoparticulate plastic exposure.