Detection of micro- and nanoplastics in cerebrospinal fluid and blood: Implications for brain diseases

The exponential growth in global plastic production has resulted in pervasive environmental contamination of micro- and nanoplastics (MNPs). Although MNPs have been detected in various human specimens, their presence in the central nervous system and potential neurological impacts remain poorly understood. This study investigated MNP concentrations in paired cerebrospinal fluid (CSF) and blood samples from patients with neurological disorders, and assessed potential associations with cerebral metabolic changes. We analyzed paired CSF (n = 20) and blood (n = 20) samples from individuals with neuroimmune diseases, neuroinfectious diseases, and controls using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to quantify 11 types of MNPs. Untargeted metabolomic profiling of CSF was performed to identify associated metabolic disturbances. Five types of MNP polymers, namely PVC, PA66, PE, PP, and PS, were detected in both biofluids. Total MNP concentrations were significantly higher in blood (121.43-151.52 µg/mL) than in CSF (7.59-16.07 µg/mL). Strong correlations between CSF and blood MNP concentrations were observed in the neuroimmune (r = 0.56, p < 0.001) and neuroinfection (r = 0.52, p < 0.01) groups, but not in controls (r = 0.01, p > 0.05). Metabolomic analysis revealed 23 disrupted pathways in the high MNP group, including FcγR-mediated phagocytosis and glycerophospholipid metabolism, with specific metabolites like N2-Acetylornithine showing strong correlations with MNP levels (r = 0.75, p < 0.01). This pilot study indicates potential associations of MNPs with metabolic changes in the brain, underscoring the need for further investigation into their roles in neurological diseases.