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Biological interactions of polystyrene nanoplastics: Their cytotoxic and immunotoxic effects on the hepatic and enteric systems
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Researchers exposed mouse and human liver cells and live mice to polystyrene nanoplastics of five different sizes and found that the smallest particles were most toxic in lab dishes, while medium and large particles caused the most liver damage in living animals. The larger particles triggered immune responses by recruiting inflammatory cells to the liver and intestines, causing tissue damage. This study reveals that nanoplastic size matters in unexpected ways, and that lab tests alone may not predict which particles are most dangerous in the body.
As emerging pollutants in the environment, nanoplastics (NPs) can cross biological barriers and be enriched in organisms, posing a greatest threat to the health of livestock and humans. However, the size-dependent toxic effects of NPs in higher mammals remain largely unknown. To determine the size-dependent potential toxicities of NPs, we exposed mouse (AML-12) and human (L02) liver cell lines in vitro, and 6-week-old C57BL/6 mice (well-known preclinical model) in vivo to five different sizes of polystyrene NPs (PS-NPs) (20, 50, 100, 200 and 500 nm). We found that ultra-small NPs (20 nm) induced the highest cytotoxicity in mouse and human liver cell lines, causing oxidative stress and mitochondrial membrane potential loss on AML-12 cells. Unexpectedly in vivo, after long-term oral exposure to PS-NPs (75 mg/kg), medium NPs (200 nm) and large NPs (500 nm) induced significant hepatotoxicity, evidenced by increased oxidative stress, liver dysfunction, and lipid metabolism disorders. Most importantly, medium or large NPs generated local immunotoxic effects via recruiting and activating more numbers of neutrophils and monocytes in the liver or intestine, which potentially resulted in increased proinflammatory cytokine secretion and the tissue damage. The discrepancy in in vitro-in vivo toxic results might be attributed to the different properties of biodistribution and tissue accumulation of different sized NPs in vivo. Our study provides new insights regarding the hepatotoxicity and immunotoxicity of NPs on human and livestock health, warranting us to take immense measures to prevent these NPs-associated health damage.
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Analysis of Biodistribution and in vivo Toxicity of Varying Sized Polystyrene Micro and Nanoplastics in Mice
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This study found that smaller plastic particles spread more widely through the bodies of mice and caused more organ damage than larger ones, particularly in the liver, kidneys, and heart. Nanoplastics (under 1 micrometer) were especially concerning because they crossed biological barriers more easily than microplastics. The results suggest that the tiniest plastic particles in our environment may pose the greatest health risks.
The role of gut microbiota in mediating increased toxicity of nano-sized polystyrene compared to micro-sized polystyrene in mice
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This mouse study found that nano-sized polystyrene plastics were significantly more toxic than micro-sized ones, causing greater gut inflammation, liver damage, and metabolic disruption. The key difference was driven by how each size affected gut bacteria: nanoplastics caused a more severe shift toward harmful bacteria and away from beneficial ones. The findings suggest that the smallest plastic particles may pose the greatest health risk because they more dramatically disrupt the gut microbiome.
Size-dependent internalization of polystyrene microplastics as a key factor in macrophages and systemic toxicity
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Researchers systematically tested how the size of polystyrene microplastics affects their uptake and toxicity in immune cells and mice. Smaller particles (0.5 micrometers) were taken up much more readily by immune cells and caused more damage, including mitochondrial dysfunction and cell death, compared to larger 5-micrometer particles. In living mice, smaller microplastics accumulated more in organs and caused broader changes in blood and metabolic markers, confirming that particle size is a key factor in microplastic toxicity.
The size-dependence and reversibility of polystyrene nanoplastics-induced lipid accumulation in mice: Possible roles of lysosomes
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This mouse study found that smaller nanoplastics (100 nm) cause more fat buildup in the liver than larger ones (500 nm), showing that size matters when it comes to health effects. Encouragingly, the liver damage was reversible after the mice stopped being exposed, suggesting the body can recover once nanoplastic intake is reduced. The damage appears to work by disrupting the cell's waste-recycling system (lysosomes).
The size-dependent effects of nanoplastics in mouse primary hepatocytes from cells to molecules
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Researchers studied how different sizes of nanoplastics affect mouse liver cells, finding that particle size significantly influences toxicity. Larger nanoplastics were more harmful at low doses, while smaller particles caused greater damage at high doses by more effectively penetrating cells and disrupting enzyme function. The study suggests that nanoplastic size is a critical factor in determining potential liver health risks.
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