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Polystyrene microplastics induce size-dependent multi-organ damage in mice: Insights into gut microbiota and fecal
Zhu Zhang1, Wenqing Chen2, Hiutung Chan2
1Golden Meditech Centre for NeuroRegeneration Sciences, Hong Kong Baptist University, Hong Kong Special Administrative Region; Department of Biology, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong Special Administrative Region.
Abstract:
Particle size is one of the most important factors in determining the biological toxicity of microplastics (MPs). In this study, we attempted to examine the systemic toxicity of polystyrene MPs of different sizes (0.5 µm MP1 and 5 µm MP2) in C57BL/6 J mice. After the mice were given oral gavage of MPs for 8 consecutive weeks, histopathology and molecular biology assays, 16 S rRNA sequencing of the gut microbiota, and untargeted metabolomics were performed. The results showed that MPs were distributed in the organs in a size-dependent manner, with smaller particles demonstrating greater biodistribution. Further analysis indicated that exposure to MPs caused multi-organ damage through distinct toxicity pathways. Specifically, exposure to 0.5 µm MP1 led to excessive accumulation and induced more serious inflammation and mechanical damage in the spleen, kidney, heart, lung, and liver. However, 5 µm MP2 led to more severe intestinal barrier dysfunction, as well as gut dysbiosis and metabolic disorder in association with neuroinflammation. These results are helpful in expanding our knowledge of the toxicity of MPs of different sizes in mammalian models.
Insights
Microplastic (MP) particle size significantly impacts biological toxicity. Smaller MPs (0.5 µm) distribute more widely, causing organ damage and inflammation, while larger MPs (5 µm) induce gut barrier dysfunction and neuroinflammation in mice.
Area of Science:
- Environmental Science
- Toxicology
- Materials Science
Background:
- Microplastic (MP) particle size is a critical determinant of biological toxicity.
- Understanding the differential toxicity of various MP sizes is crucial for risk assessment.
Purpose of the Study:
- To investigate the systemic toxicity of different-sized polystyrene MPs (0.5 µm and 5 µm) in a mammalian model.
- To elucidate the size-dependent biodistribution and toxicity pathways of MPs.
Main Methods:
- Oral gavage administration of MPs to C57BL/6J mice for 8 weeks.
- Histopathology, molecular biology assays, 16S rRNA sequencing, and untargeted metabolomics were employed.
- Analysis of MP distribution and organ-specific toxicity.
Main Results:
- MPs exhibited size-dependent biodistribution, with smaller particles showing greater distribution in organs.
- 0.5 µm MPs caused significant inflammation and mechanical damage in multiple organs (spleen, kidney, heart, lung, liver).
- 5 µm MPs led to severe intestinal barrier dysfunction, gut dysbiosis, metabolic disorder, and neuroinflammation.
Conclusions:
- MP size dictates biodistribution and toxicity mechanisms.
- Smaller MPs pose a greater risk of systemic organ damage, while larger MPs primarily affect the gut and associated neurological pathways.
- Findings advance the understanding of microplastic toxicity in mammals.
