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Oral feeding of nanoplastics affects brain function of mice by inducing macrophage IL-1 signal in the intestine
Summary
Researchers found that when mice consumed nanoplastics, the tiny particles triggered immune cells in the gut to produce an inflammatory signal (IL-1) that traveled to the brain and impaired cognitive function. Nanoplastics were more potent at activating this gut-brain immune pathway than larger microplastics. This study reveals a concerning mechanism by which swallowing nanoplastics in food or water could affect brain health through the gut immune system.
Nanoplastics (NPs) as contaminants in food and water have drawn increasing public attention. However, little is known about how NPs shape the gut immune landscape after injection. In this study, we fabricate NPs (∼500 nm) and microplastics (MPs) (∼2 μm) and evaluate their in vivo effects by feeding them to mice. The results suggest that NPs show a better ability to induce gut macrophage activation than MPs. In addition, NPs trigger gut interleukin-1 (IL-1)-producing macrophage reprogramming via inducing lysosomal damage. More importantly, IL-1 signaling from the intestine can affect brain immunity, leading to microglial activation and Th17 differentiation, all of which correlates with a decline in cognitive and short-term memory in NP-fed mice. Thus, this study provides insight into the mechanism of action of the gut-brain axis, delineates the way NPs reduce brain function, and highlights the importance of fixing the plastic pollution problem worldwide.