Blood-brain barrier damage accelerates the accumulation of micro- and nanoplastics in the human central nervous system.

The widespread use of plastics has led to increased micro- and nanoplastics (MNPs) pollution, resulting in significant environmental challenges and concerns about potential harm to human health. This study investigated whether certain types of MNPs can accumulate in the human central nervous system (CNS) and trigger inflammatory responses, particularly after CNS infection. Our analysis of 28 cerebrospinal fluid (CSF) samples from 28 patients with or without CNS infection revealed that only polystyrene (PS), polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) were capable of selectively entering the human CNS. Concentrations of PP and PE were positively correlated with the CSF albumin index. The levels of interleukin-6 (IL-6) and interleukin-8 (IL-8) were significantly increased in patients with CNS infections. However, concentrations of MNPs were not significantly associated with CSF levels of IL-6 or IL-8. Overall, these findings suggest that specific MNPs can penetrate the human CNS, especially after impairment of the blood-brain barrier. Notably, MNPs derived from commonly used plastics did not significantly induce or exacerbate inflammation in the human CNS.