Long-term exposure to polystyrene microplastics induces hepatotoxicity by altering lipid signatures in C57BL/6J mice

Exploring the micro- and nanoplastics-diabetes nexus: Shattered barriers, toxic links, and methodological horizons

Micro- and nanoplastics (MNPs) are emerging environmental contaminants with increasing evidence linking them to metabolic dysfunction, including diabetes-related outcomes. While experimental studies have demonstrated that MNPs disrupt glucose metabolism, insulin signaling, and lipid homeostasis through oxidative stress, systemic inflammation, and endocrine disruption, the implications for human health remain largely unexplored. Given the widespread presence of MNPs in food, water, and air, chronic low-dose exposure may contribute to metabolic disorders, yet epidemiological data are scarce. This review synthesizes current findings on MNP-induced metabolic disturbances, highlighting their impact on insulin resistance, hepatic fat accumulation, gut microbiota dysbiosis, and adipose tissue dysfunction. Additionally, we evaluate the analytical methodologies used to detect MNPs in biological systems and assess the relevance of exposure levels in real-world scenarios. By contextualizing these mechanisms within a broader public health framework, this review underscores the urgent need for large-scale human studies to establish causal links between MNP exposure and metabolic diseases. Addressing these knowledge gaps is critical for informing risk assessment, regulatory policies, and future research directions aimed at mitigating the metabolic risks associated with environmental plastic pollution.

Polystyrene microplastics induce hepatic lipid metabolism and energy disorder by upregulating the NR4A1-AMPK signaling pathway

Microplastics (MPs) are widespread throughout global ecosystems, and their impact on living organisms has garnered increasing attention in recent years. Research has demonstrated that exposure to different sizes (0.08-100 μm) polystyrene microplastics (PS-MPs) can disrupt hepatic lipid and energy metabolism while promoting oxidative stress. Despite these findings, the precise molecular mechanisms underlying PS-MP-induced toxicity are not fully understood. NR4A1 is known to regulate apoptosis and lipid metabolism, but few studies have explored its role in modulating hepatic lipid metabolism following PS-MP exposure. In this study, animal experiments showed that PS-MPs reduced triglyceride levels and significantly increased reactive oxygen species (ROS) in liver tissue. Transcriptional profiles of mouse liver tissues were processed and analyzed using Ingenuity Pathway Analysis (IPA) software and Gene Set Enrichment Analysis (GSEA) to identify relevant pathways and molecular signatures. The results revealed a significant upregulation in NR4A1 gene expression after exposure to PS-MPs. PS-MP accumulation in the liver activated NR4A1 and the AMPK-autophagy pathway, reducing lipid biosynthesis. In vitro study, NR4A1 knockdown in hepatocytes exposed to PS-MPs reduced the expression of AMPK and lipid metabolism-related proteins. In summary, this study indicated that PS-MPs disrupt lipid metabolism in the liver by affecting the NR4A1, leading to liver damage. Prolonged exposure to these microplastics could raise concerns about long-term liver health and the regulation of overall metabolic functions.

A physiologically based toxicokinetic model for microplastics and nanoplastics in mice after oral exposure and its implications for human dietary exposure assessment

Evidence of microplastics (MPs) and nanoplastics (NPs) in foods and daily-use products, along with their frequent detection in the human body, has raised concerns regarding their potential impact on human health through dietary ingestion. However, there is a lack of quantitative tools to simulate their bioaccumulation and tissue distribution following environmental exposure. To address this gap, we developed the first physiologically based toxicokinetic (PBTK) model for predicting the biodistribution of MPs and NPs in mice following oral exposure under various exposure scenarios. This novel model incorporated key kinetic mass transport processes, such as membrane permeability, albumin binding, and cellular uptake. We identified that the absorption rate in the gastrointestinal tract and fecal excretion rate constant had significant impacts on organ dosimetry. Our regression analysis indicated that the size-dependent dissociation constant and urine clearance rate constant sharply increased by a factor of 3 as NPs particle size increased to 1 µm. Finally, we developed a graphical user interface to enable interactive visualization and analysis for future applications, supporting human dietary exposure and risk assessment using available food consumption data and MPs/NPs residue data. The simulation results offer a mechanistic perspective, enhancing understanding of the internal organ dosimetry burden and health impacts from dietary exposure to MPs and NPs.

Mechanisms of eco-corona effects on micro(nano)plastics in marine medaka: Insights into translocation, immunity, and energy metabolism

Biomolecules, prevalent in the marine environment, can readily adsorb onto the surface of micro(nano)plastics (MNPs), forming eco-corona. This study indicated that 50 nm polystyrene nanoplastics (NP50), whether wrapped with eco-corona or not, can passively enter embryos, whereas 5 µm polystyrene microplastics (MP5) cannot. Additionally, translocation of MP5 from the intestine to the liver was observed in larvae, a process facilitated by eco-corona. Notably, eco-corona prolonged the retention time of MNPs in larvae. However, NP50 was more challenging to purify than MP5, irrespective of the presence of eco-corona. Interestingly, eco-corona degraded in the intestine during the uptake of MNPs, and the hard coronae that readily formed on NP50 may restrict the degradation rate. Although NP50 significantly disrupted larval microbiota homeostasis compared with MP5, eco-corona was more likely to exacerbate MP5's damage to the intestine and liver by disrupting microbiota homeostasis. Additionally, NP50 caused more significant damage to immunity and energy metabolism compared with MP5, regardless of the presence of eco-corona. This study revealed that previously overlooked biomolecules in the marine environment can enhance the translocation of MNPs and subsequently exacerbate their toxic effects, providing theoretical support for assessing the ecological risks of MNPs in real environments.

Degradation of Polymer Materials in the Environment and Its Impact on the Health of Experimental Animals: A Review

The extensive use of polymeric materials has resulted in significant environmental pollution, prompting the need for a deeper understanding of their degradation processes and impacts. This review provides a comprehensive analysis of the degradation of polymeric materials in the environment and their impact on the health of experimental animals. It identifies common polymers, delineates their degradation pathways, and describes the resulting products under different environmental conditions. The review covers physical, chemical, and biological degradation mechanisms, highlighting the complex interplay of factors influencing these processes. Furthermore, it examines the health implications of degradation products, using experimental animals as proxies for assessing potential risks to human health. By synthesizing current research, the review focuses on studies related to small organisms (primarily rodents and invertebrates, supplemented by fish and mollusks) to explore the effects of polymer materials on living organisms and underscores the urgency of developing and implementing effective polymer waste management strategies. These strategies are crucial for mitigating the adverse environmental and health impacts of polymer degradation, thus promoting a more sustainable interaction between human activities and the natural environment.

Gut microbiota and liver metabolomics reveal the potential mechanism of Lactobacillus rhamnosus GG modulating the liver toxicity caused by polystyrene microplastics in mice

Microplastics (MPs) are known to cause liver toxicity as they can spread through the food chain. Most researches on their toxicity have focused on individual organs, neglecting the crucial "gut-liver axis"-a bidirectional communication pathway between the gut and liver. Probiotics have shown promise in modulating the effects of environmental pollutants. In this study, we exposed mice to Lactobacillus rhamnosus GG (LGG, 100 mg/kg b.w./d) and/or polystyrene microplastics (PS-MPs, 5 mg/kg b.w./d) for 28 d via gavage to investigate how probiotics influence live toxicity through the gut-liver axis. Our results demonstrated that PS-MPs induced liver inflammation (increased IL-6 and TNF-α) and disrupted lipid metabolism. However, when combined with LGG, these effects were alleviated. LGG also improved colon health, rectifying ciliary defects and abnormal mucus secretion caused by PS-MPs. Furthermore, LGG improved gut microbiota dysbiosis induced by PS-MPs. Metabolomics and gene expression analysis (Cyp7a1 and Cyp7b1) indicated that LGG modulated bile acid metabolism. In summary, LGG appears to protect the liver by maintaining gut homeostasis, enhancing gut barrier integrity, and reducing the liver inflammation. These findings confirm the potential of LGG to modulate liver toxicity caused by PS-MPs through the gut-liver axis, offering insights into probiotics' application for environmental pollutant detoxification.