Comprehensive phenotyping and multi-omic profiling in the toxicity assessment of nanopolystyrene with different surface properties

Transgenerational reproductive toxicity induced by carboxyl and amino charged microplastics at environmental concentrations in Caenorhabditis elegans: Involvement of histone methylation

Microplastics, recognized as emerging contaminants, are commonly observed to be charged in the environment, potentially exerting toxic effects on various organisms. However, the transgenerational reproductive toxicity and underlying mechanisms of polystyrene (PS), particularly carboxyl-modified PS (PS-COOH) and amino-modified PS (PS-NH2), remain largely unexplored. In this study, the parental generation (P0) of Caenorhabditis elegans was subjected to environmental concentrations (0.1-100 μg/L) of PS, PS-COOH, and PS-NH2, with subsequent generations (F1-F4) cultured under normal conditions. Exposure to PS-NH2 at concentrations of 10-100 μg/L exhibited more pronounced reproductive toxicity compared to PS or PS-COOH, resulting in decreased brood size, egg ejection rate, number of fertilized eggs, and cell corpses per gonad. Similarly, maternal exposure to 100 μg/L of PS-NH2 induced more severe transgenerational reproductive effects in C. elegans. Significant increases in H3 on lysine 4 dimethylation (H3K4me2) and H3 on lysine 9 trimethylation (H3K9me3) levels were observed in the subsequent generation, concurrent with the transgenerational upregulation of set-30 and met-2 following parental exposure to PS, PS-COOH, and PS-NH2. Correlation analyses revealed significant associations between the expression of these genes with the reproductive ability. Molecular docking studies suggested that PS-NH2 exhibited higher affinity for SET-30 and MET-2. Further analysis demonstrated that transgenerational effects on reproduction were absent in set-30(gk315) and met-2(n4256) mutants, highlighting the pivotal role of set-30 and met-2 in mediating the transgenerational effect. This study provides novel insights into the environmental risks associated with negatively and positively charged microplastics.

Comparing the effects and mechanisms of exposure to polystyrene nanoplastics with different functional groups on the male reproductive system

After aging in the environment, some nanoplastics will carry different charges and functional groups, thereby altering their toxicological effects. To evaluate the potential impact of aging of nanoplastics on the mammalian reproductive system, we exposed C57BL/6 male mice to a dose of 5 mg/kg/d polystyrene nanoparticles (PS-NPs) with different functional groups (unmodified, carboxyl functionalized and amino functionalized) for 45 days for this study. The results suggest that PS-NPs with different functional groups triggered oxidative stress, a decreased in the testis index, disruption of the outer wall of the seminiferous tubules, reduction in the number of spermatogonia cells and sperm counts, and an increased in sperm malformations. We performed GO and KEGG enrichment analysis on the differentially expressed proteins, and found they were mainly enriched in protein transport, RNA splicing and mTOR signaling. We confirmed that the PI3K-AKT-mTOR pathway is over activated, which may lead to reduction of spermatogonia stem cells by over differentiation. Strikingly, PS-NPs with functional group modifications are more toxic than those of unmodified polystyrene, and that PS-NPs with positively charged amino modifications are the most toxic. This study provides a new understanding for correctly evaluating the toxicological effects of plastic aging, and of the mechanism responsible for the reproductive toxicity caused by nanoplastics.

Uptake and effect of carboxyl-modified polystyrene microplastics on cotton plants

Microplastics (MPs) have emerged as a significant global environmental concern, particularly within agricultural soil systems. The extensive use of plastic film mulching in cotton cultivation has led to the alarming presence of MP pollution in cotton fields. However, the uptake and effects of MPs on the growth of cotton plants are poorly understood. In this study, we conducted a comprehensive analysis of hydroponically cultured cotton seedlings at the phenotypic, transcriptional, and metabolic levels after exposure to carboxyl-modified polystyrene microplastics (PS-COOH). Treatment with three concentrations of PS-COOH (100, 300, and 500 mg/L) resulted in notable growth inhibition of treated plants and exhibited a dose-dependent effect. And, PS-COOH can invade cotton roots and be absorbed through the intercellular spaces via apoplastic uptake, with accumulation commensurate with treatment duration. Transcriptomic analysis showed significant up-regulation of genes associated with antioxidant activity in response to 300 mg/L PS-COOH treatment, suggesting the induction of oxidative stress. In addition, the PS-COOH treatment activated the phenylpropanoid biosynthesis pathway, leading to lignin and flavonoid accumulation, and altered sucrose catabolism. These findings illustrate the absorption and effects of MPs on cotton seedlings and offer valuable insights into the potential toxicity of MPs to plants in soil mulched with plastic film.

An integrated analysis of the fecal metabolome and metagenome reveals the distinct effects of differentially charged nanoplastics on the gut microbiota-associated metabolites in mice

Whether nanoplastics with differential charges cause intestinal impairment via distinct mechanisms remains unclear. We investigated the relationship between fecal metabolites and the gut microbiome, and potential biomarkers thereof, in mice following exposure to differentially charged polystyrene nanoplastics (PS-NPs). Metagenomic analysis revealed that exposure to differentially charged PS-NPs resulted in alterations in the abundances of Bilophila_wadsworthia, Helicobacter apodemus, and Helicobacter typhlonius. A total of 237 fecal metabolites were significantly altered in mice that exhibited intestinal impairment, and these included 10 gut microbiota-related fecal metabolites that accurately discriminated impaired intestinal samples from the control. Additionally, the specific gut microbiome-related fecal metabolite-based model approach for the prediction of intestinal impairment in mice had an area under the curve (AUC) of 1.0 in the PS (without charge) group, an AUC of 0.94 in the PS-NH2 (positive charge) group, and an AUC of 0.86 in the PS-COOH (negative charge) group. Thus, the model showed promising evaluable accuracy for the prediction of intestinal impairment induced by nanoplastics in a charge-specific manner. Our study demonstrates that the fecal metabolome of mice with intestinal impairment following exposure to differentially charged nanoplastics is associated with changes in the gut microbiome. The identified biomarkers have potential application for the detection of intestinal impairment after exposure to negative, positive, or noncharged nanomaterials.

Photoaged microplastics induce neurotoxicity associated with damage to serotonergic, glutamatergic, dopaminergic, and GABAergic neuronal systems in Caenorhabditis elegans

Microplastics (MPs) are ubiquitous environmental contaminants that cause neurotoxicity in various organisms. MPs are typically affected by light irradiation and undergo photoaging. However, the neurotoxic effects of photoaged polystyrene (P-PS) and its underlying mechanisms remain unclear. In this study, locomotion behaviors, neuronal development, neurotransmitter levels, and the expression of neurotransmission-related genes were investigated in Caenorhabditis elegans exposed to P-PS at environment-relevant concentrations (0.1-100 μg/L). The characterization results showed that photoaging accelerated the aging process and changed the physicochemical properties of the MPs. The toxicity results suggested that exposure to 1-100 μg/L P-PS caused more severe neurotoxicity than virgin polystyrene (V-PS) with endpoints of head thrashes, body bends, wavelength, and mean amplitude. Exposure to P-PS also altered the fluorescence intensity and neurodegeneration percentage of serotonergic, glutamatergic, dopaminergic, and aminobutyric acid (GABA) in transgenic nematodes. Similarly, significant reductions in the levels of these neurotransmitters were also observed. Based on Pearson's correlation, locomotion behaviors were negatively correlated with the neurotransmission of serotonin, glutamate, dopamine, and GABA. Further investigation suggested that the expression of neurotransmitter-related genes (e.g., tph-1, eat-4, and unc-46) was significantly altered in the nematodes. Collectively, the neurotoxic effects of P-PS were attributed to abnormal neurotransmission. This study highlights the potential toxicity of MPs photoaged under environmentally relevant conditions.

Exposure to epoxy-modified nanoplastics in the range of μg/L causes dysregulated intestinal permeability, reproductive capacity, and mitochondrial homeostasis by affecting antioxidant system in Caenorhabditis elegans

Although surface chemically modified nanopolystyrene (PS) has been reported to have potential toxicity toward organisms, the impact of epoxy modification on the toxicity of PS remains largely unknown. In this study, we first investigated the prolonged exposure effects of epoxy-modified PS (PS-C2H3O) in the range of μg/L on Caenorhabditis elegans (C. elegans) including general toxicity, target organ toxicity, and organelle toxicity. Our data revealed that C. elegans exposed to PS-C2H3O led to the alterations in increased lethality (≥ 1000 μg/L), shortened body length (≥ 100 μg/L), and decreased locomotion capacity (≥ 1 μg/L). In addition, toxicity analysis on target organs and organelles indicated that exposure to PS-C2H3O enhanced intestinal permeability (≥ 100 μg/L) by inhibiting the transcriptional levels of acs-22 (encoding fatty acid transport protein) (≥ 100 μg/L) and hmp-2 (encoding α-catenin) (≥ 1000 μg/L), reduced reproductive capacity (≥ 10 μg/L), and dysregulated mitochondrial homeostasis (≥ 1 μg/L). Moreover, the activation of antioxidant enzyme system could help nematodes against the toxicity caused by PS-C2H3O exposure (≥ 10 μg/L). Furthermore, we also compared the toxicity of PS-C2H3O with other chemically modified derivatives of PS, and the toxicity order was PS-NH2 > PS-SOOOH > PS-C2H3O > PS-COOH > PS > PS-PEG. Our study highlights the potential environmental impact of PS and its derivatives on organisms and suggests that the toxicity of nanoplastics may be charge-dependent.

Unveiling potentially convergent key events related to adverse outcome pathways induced by silver nanoparticles via cross-species omics-scale analysis

The adverse effects of silver nanoparticles (AgNPs) have been studied in various models. However, there has been discordance between molecular responses across the literature, attributed to methodological biases and the physicochemical variability of AgNPs. In this study, a gene pathway meta-analysis was conducted to identify convergent and divergent key events (KEs) associated with AgNPs and explore common patterns of these KEs across species. We performed a cross-species analysis of transcriptomic data from multiple studies involving various AgNPs exposure. Pathway enrichment analysis revealed a set of pathways linked to oxidative stress, apoptosis, and metabolite and lipid metabolism, which are considered potentially conserved KEs across species. Subsequently, experiments confirmed that oxidative stress responses could be early KEs in both Caenorhabditis elegans and HepG2 cells. Moreover, AgNPs preferentially impaired the mitochondria, as evidenced by mitochondrial fragmentation and dysfunction. Furthermore, disruption of amino acids, nucleotides, sulfur compounds, glycerolipids, and glycerophospholipids metabolism were in good agreement with gene pathway shreds of evidence. Our findings imply that, although there may be organism-specific responses, potentially conserved events could exist regardless of species and physicochemical factors. These results provide valuable insights into the development of adverse outcome pathways of AgNPs across species and the regulatory toxicity of AgNPs.

The concentration-dependent physiological damage, oxidative stress, and DNA lesions in Caenorhabditis elegans by subacute exposure to landfill leachate

The leakage of landfill leachate (LL) into environmental media would be happened even in the sanitary/controlled landfill, due to the deterioration of geomembrane and the blockage of drainage system after long-term operation. Considering the complex composition and high concentration of pollutants in LL, its toxicity assessment should be conducted as a whole liquid contaminant. Therefore, the impacts of LL on Caenorhabditis elegans (C. elegans) were investigated under the condition of different exposure time and exposure volume fraction (EVF). The stimulating effects on locomotion behavior and growth of C. elegans were observed after acute (24 h) exposure to LL, which were increased firstly and then decreased with the increase of EVF. Meanwhile, the intestinal barrier was not affected by LL, and levels of reactive oxygen species (ROS) and cell apoptosis significantly decreased. However, stimulation and inhibition effects on locomotion behavior and growth of C. elegans were observed when subacute (72 h) exposure to 0.25%-0.5% and 1%-4% of LL, respectively. The intestinal injury index and levels of ROS and cell apoptosis significantly increased when EVF were 2% and 4%. Although the acute exposure of LL had resulted in obviously biological adaptability and antioxidant defense in C. elegans, the protective mechanisms failed to be induced as the exposure time increased (subacute exposure). The toxic effects were confirmed by the down-regulation of genes associated with antioxidant defense and neurobehavior, accompanied by the up-regulation of intestinal injury and cell apoptosis related genes. Moreover, the disturbance of metabolic pathways that associated with locomotion behaviors, growth, and antioxidant defense provided good supplementary evidence for the confirmation of oxidative stress in C. elegans. The research results verified the potential of C. elegans as model organism to determine the complex toxic effects of LL.

Impacts of polypropylene microplastics on lipid profiles of mouse liver uncovered by lipidomics analysis and Raman spectroscopy

Microplastics (MPs) are emerging contaminants, and there are only limited studies reporting the impacts of some MPs on liver lipid metabolism in animals. In this study, we investigated the accumulation of polypropylene-MPs in mouse liver and unraveled the change in lipid metabolic profiles by both lipidomics and Raman spectroscopy. Polypropylene-MP exposure did not cause obvious health symptoms, but hematoxylin-eosin staining showed pathological changes that polypropylene-MPs induced lipid droplet accumulation in liver. Lipidomics results showed a significant change in lipid metabolic profiles and the most influenced categories were triglycerides, fatty acids, free fatty acids and lysophosphatidylcholine, implying the effects of polypropylene-MPs on the hemostasis of lipid droplet biogenesis and catabolism. Most altered lipids contained unsaturated bonds and polyunsaturated phospholipids, possibly affecting the fluidity and curvature of membrane surfaces. Raman spectroscopy confirmed that the major spectral alterations of liver tissues were related to lipids, evidencing the altered lipid metabolism and cell membrane components in the presence of polypropylene-MPs. Our findings firstly disclosed the impacts of polypropylene-MPs on lipid metabolisms in mouse liver and hinted at their detrimental disturbance on membrane properties, cellular lipid storage and oxidation regulation, helping our deeper understanding on the toxicities and corresponding risks of polypropylene-MPs to mammals.

SKN-1/Nrf2-dependent regulation of mitochondrial homeostasis modulates transgenerational toxicity induced by nanoplastics with different surface charges in Caenorhabditis elegans

The toxic effects of nanoplastics on transgenerational toxicity in environmental organisms and the involved mechanisms remain poorly comprehended. This study aimed to identify the role of SKN-1/Nrf2-dependent regulation of mitochondrial homeostasis in response to transgenerational toxicity caused by changes in nanoplastic surface charges in Caenorhabditis elegans (C. elegans). Our results revealed that compared with the wild-type control and PS exposed groups, exposure to PS-NH₂ or PS-SOOOH at environmentally relevant concentrations (ERC) of ≥ 1 μg/L caused transgenerational reproductive toxicity, inhibited mitochondrial unfolded protein responses (UPR) by downregulating the transcription levels of hsp-6, ubl-5, dve-1, atfs-1, haf-1, and clpp-1, membrane potential by downregulating phb-1 and phb-2, and promoted mitochondrial apoptosis by downregulating ced-4 and ced-3 and upregulating ced-9, DNA damage by upregulating hus-1, cep-1, egl-1, reactive oxygen species (ROS) by upregulating nduf-7 and nuo-6, ultimately resulting in mitochondrial homeostasis. Additionally, further study indicated that SKN-1/Nrf2 mediated antioxidant response to alleviate PS-induced toxicity in the P0 generation and dysregulated mitochondrial homeostasis to enhance PS-NH₂ or PS-SOOOH-induced transgenerational toxicity. Our study highlights the momentous role of SKN-1/Nrf2 mediated mitochondrial homeostasis in the response to nanoplastics caused transgenerational toxicity in environmental organisms.

Lipid class-dependent alterations of Caenorhabditis elegans under harmane exposure

Altered lipid patterns in Caenorhabditis elegans (C. elegans) resulting from exposure to harmane remain to be explored. In this study, untargeted lipidomics was carried out to elucidate the effects of acute exposure to harmane on the lipidome of C. elegans. Exposure to the compound was evaluated based on the reproduction ability of the worms at 0.1 and 1 μg/mL. No significant effects of harmane were observed at these concentrations. Furthermore, we found that the modulatory effects of harmane on the lipidome of C. elegans at 1 μg/mL were lipid class dependent. In particular, harmane-treated worms were enriched in triglycerides and fatty acids, regardless of the degree of saturation. Glycerophospholipids were generally down-regulated. Furthermore, functional analyses suggested that there was a reduction in lipid membrane bilayer-related terms, and in some related to the mitochondria, and endoplasmic reticulum of C. elegans when treated with harmane. Lipid droplets and storage appeared to be up-regulated. In conclusion, our findings suggest that harmane exposure affects the lipidome of C. elegans in a sophisticated manner. Further investigations are required to elucidate the molecular mechanisms underlying these lipid pattern changes.

Carboxyl-modified polystyrene microplastics induces neurotoxicity by affecting dopamine, glutamate, serotonin, and GABA neurotransmission in Caenorhabditis elegans

Microplastics (MPs) are ubiquitous in various environmental media and have potential toxicity. However, the neurotoxicity of carboxyl-modified polystyrene microplastics (PS-COOH) and their mechanisms remain unclear. In this study, Caenorhabditis elegans was used as a model to examine the neurotoxicity of polystyrene microplastic (PS) and PS-COOH concentrations ranging from 0.1 to 100 μg/L. Locomotion behavior, neuron development, neurotransmitter level, and neurotransmitter-related gene expression were selected as assessment endpoints. Exposure to low concentrations (1 μg/L) of PS-COOH caused more severe neurotoxicity than exposure to pristine PS. In transgenic nematodes, exposure to PS-COOH at 10-100 μg/L significantly increased the fluorescence intensity of dopaminergic, glutamatergic, serotonergic, and aminobutyric acid (GABA)ergic neurons compared to that of the control. Further studies showed that exposure to 100 μg/L PS-COOH can significantly affect the levels of glutamate, serotonin, dopamine, and GABA in nematodes. Likewise, in the present study, the expression of genes involved in neurotransmission was altered in worms. These results suggest that PS-COOH exerts neurotoxicity by affecting neurotransmission of dopamine, glutamate, serotonin, and GABA. This study provides new insights into the underlying mechanisms and potential risks associated with PS-COOH.

Evaluation of nanoplastics toxicity in the soil nematode Caenorhabditis elegans by iTRAQ-based quantitative proteomics

Plastic pollution is recognized as a major threat to ecosystems in the 21st century. Large plastic objects undergo biotic and abiotic degradation to generate micro- and nano-sized plastic pieces. Despite tremendous efforts to evaluate the adverse effects of microplastics, a comprehensive understanding of the toxicity of nanoplastics remains elusive, especially at the protein level. To this end, we used isobaric-tag-for-relative-and-absolute-quantitation-based quantitative proteomics to investigate the proteome dynamics of the soil nematode Caenorhabditis elegans in response to exposure to 100 nm polystyrene nanoplastics (PS-NPs). After 48 h of exposure to 0.1, 1, or 10 mg/L PS-NPs, 136 out of 1684 proteins were differentially expressed and 108 of these proteins were upregulated. These proteins were related to ribosome biogenesis, translation, proteolysis, kinases, protein processing in the endoplasmic reticulum, and energy metabolism. Remarkably, changes in proteome dynamics in response to exposure to PS-NPs were consistent with the phenotypic defects of C. elegans. Collectively, our findings demonstrate that disruption of proteome homeostasis is a biological consequence of PS-NPs accumulation in C. elegans, which provides insights into the molecular mechanisms underlying the toxicology of nanoplastics.

Hazard of polystyrene micro-and nanospheres to selected aquatic and terrestrial organisms

Plastics contamination in the environment is a major concern. Risk assessment of micro- and nanoplastics (MPL and NPL) poses significant challenges due to MPL and NPL heterogeneity regarding compositional polymers, particle sizes and morphologies in the environment. Yet, there exists considerable toxicological literature on commercial polystyrene (PS) micro- and nanospheres. Although such particles do not directly represent the environmental MPL and NPL, their toxicity data should be used to advance the hazard assessment of plastics. Here, toxicity data of PS micro- and nanospheres for microorganisms, aquatic and terrestrial invertebrates, fish, and higher plants was collected and analyzed. The evaluation of 294 papers revealed that aquatic invertebrates were the most studied organisms, nanosized PS was studied more often than microsized PS, acute exposures prevailed over chronic exposures, the toxicity of PS suspension additives was rarely addressed, and ∼40 % of data indicated no organismal effects of PS. Toxicity mechanisms were mainly studied in fish and nematode Caenorhabditis elegans, providing guidance for relevant studies in higher organisms. Future studies should focus on environmentally relevant plastics concentrations, wide range of organisms, co-exposures with other pollutants, and method development for plastics identification and quantification to fill the gap of bioaccumulation assessment of plastics.

Lipidomic analysis of mussel hemocytes exposed to polystyrene nanoplastics

Plastics production and usage has exponentially increased in the last decades around the world. Due to the insufficient waste management, a significant amount of plastic ends up in the environment, where they tend to fragment into micro- and nano-plastics (NPs), and accumulate in aquatic organisms with still unknown effects. Although studies have indicated that lipid metabolism is a main target of NPs, this mechanism has not been extensively explored. In this study, we evaluated changes in the lipidome of mussel hemocytes after exposure to polystyrene (PS) NPs of 50 and 500 nm, at two different concentrations (10⁶ and 10⁹ particles/mL) for 24 h. The lipidome of hemocytes, analyzed by FIA-ESI (±) Orbitrap, was characterized by a relatively high abundance of cholesteryl esters (CEs) and phosphatidylcholine-plasmalogens (PC-Os/PC-Ps), involved in cell's defense against oxidative stress and membrane reorganization. In hemocytes exposed to PS NPs, a number of highly unsaturated membrane lipids were down-regulated, indicating a reorganization of the cell membranes after exposure to the particles and an oxidation of lipids with a high number of double bonds. This reduction was more evident after exposure to 50 nm NPs -both concentrations- and 500 nm NPs -high concentration-. The analysis of culture medium suggested increased release of vesicles enriched in triglycerides (TGs). The relevance of these responses to NP exposure on the immune function of hemocytes remains to be investigated.

Induction of transgenerational toxicity is associated with the activated germline insulin signals in nematodes exposed to nanoplastic at predicted environmental concentrations

Exposure to nanoplastics can induce toxicity on organisms at both parental generation (P0-G) and the offspring. However, the underlying mechanism remains unknown. Using Caenorhabditis elegans as a model organism, exposure to 20-nm polystyrene nanoparticle (PS-NP) (1-100 μg/L) upregulated the expressions of insulin ligands (INS-39, INS-3, and DAF-28), and this increase could be further detected in the offspring after PS-NP exposure. Germline ins-39, ins-3, and daf-28 RNAi induced resistance to transgenerational toxicity of PS-NP, indicating that increase in expression of these three insulin ligands mediated induction of transgenerational toxicity. These three insulin ligands transgenerationally activated function of insulin receptor DAF-2 to control transgenerational toxicity of PS-NP. Exposure to 1-100 μg/L PS-NP further upregulated DAF-2, AGE-1, and AKT-1 expressions and downregulated DAF-16 expression. During transgenerational toxicity control, DAF-16/AKT-1/AGE-1 was identified as downstream signaling cascade of DAF-2. Moreover, transcriptional factor DAF-16 activated two downstream targets of HSP-6 (a mitochondrial UPR marker) and SOD-3 (a mitochondrial SOD) to modulate transgenerational toxicity of PS-NP. Our findings indicate a crucial link between activation of insulin signaling and induction of transgenerational toxicity of nanoplastics at low concentrations in organisms.

Ecotoxicological effects of plastics on plants, soil fauna and microorganisms: A meta-analysis

The interactions of plastics and soil organisms are complex and inconsistent observations on the effects of plastics have been made in published studies. In this study, we assessed the effects of plastic exposure on plants, fauna and microbial communities, with a meta-analysis. Using a total of 2936 observations from 140 publications, we analysed how responses in plants, soil fauna and microorganisms depended on the plastic concentration, size, type, species and exposure media. We found that overall plastics caused substantial detrimental effects to plants and fauna, but less so to microbial diversity and richness. Plastic concentration was one of the most important factors explaining variations in plant and faunal responses. Larger plastics (>1 μm) caused unfavourable changes to plant growth, germination and oxidative stress, while nanoplastics (NPs; ≤ 1 μm) only increased oxidative stress. On the contrary, there was a clear trend showing that small plastics adversely affected fauna reproduction, survival and locomotion than large plastics. Plant responses were indifferent to plastic type, with most studies conducted using polyethylene (PE) and polystyrene (PS) plastics, but soil fauna were frequently more sensitive to PS than to PE exposure. Plant species played a vital role in some parameters, with the effects of plastics being considerably greater on vegetable plants than on cereal plants.

Polystyrene nanoplastics induce profound metabolic shift in human cells as revealed by integrated proteomic and metabolomic analysis

Nanoplastics (NPLs) are widespread in our environment. However, their impacts on human health and precise toxicity mechanisms remain poorly understood. Here we studied the internalization, release, and cytotoxicity of polystyrene nanoplastics (PSNPs) using the renal tubular epithelial cell line HKC and human derived liver cell line HL-7702. We also employed an integrated proteomic and metabolomic approach to investigate the potential biological effects of PSNPs on HKC cells. The abundances of 4770 proteins and 100 metabolites were quantified, with 785 proteins and 17 metabolites detected with altered levels in response to PSNPs. Most of the differential proteins and metabolites were enriched in a variety of metabolic pathways, for example, glycolysis, citrate cycle, oxidative phosphorylation, and amino acid metabolism, suggesting the potential effects of NPLs on global cellular metabolism shift in human cells. The altered energy metabolism induced by PSNPs was further confirmed by a Seahorse analysis. Moreover, lysosomal distribution study and western blotting showed that mTORC1 signaling, a central regulator of cellular metabolism, was inhibited upon nanoplastic exposure, likely serving as the link between lysosome dysfunction and metabolic defects. Taken together, our findings systematically mapped the key molecular changes induced by PSNPs in human cells and provide comprehensive biological insights for the risk estimation of NPLs contamination.

Caenorhabditis elegans deep lipidome profiling by using integrative mass spectrometry acquisitions reveals significantly altered lipid networks

Lipidomics coverage improvement is essential for functional lipid and pathway construction. A powerful approach to discovering organism lipidome is to combine various data acquisitions, such as full scan mass spectrometry (full MS), data-dependent acquisition (DDA), and data-independent acquisition (DIA). Caenorhabditis elegans (C. elegans) is a useful model for discovering toxic-induced metabolism, high-throughput drug screening, and a variety of human disease pathways. To determine the lipidome of C. elegans and investigate lipid disruption from the molecular level to the system biology level, we used integrative data acquisition. The methyl-tert-butyl ether method was used to extract L4 stage C. elegans after exposure to triclosan (TCS), perfluorooctanoic acid, and nanopolystyrene (nPS). Full MS, DDA, and DIA integrations were performed to comprehensively profile the C. elegans lipidome by Q-Exactive Plus MS. All annotated lipids were then analyzed using lipid ontology and pathway analysis. We annotated up to 940 lipids from 20 lipid classes involved in various functions and pathways. The biological investigations revealed that when C. elegans were exposed to nPS, lipid droplets were disrupted, whereas plasma membrane-functionalized lipids were likely to be changed in the TCS treatment group. The nPS treatment caused a significant disruption in lipid storage. Triacylglycerol, glycerophospholipid, and ether class lipids were those primarily hindered by toxicants. Finally, toxicant exposure frequently involved numerous lipid-related pathways, including the phosphoinositide 3-kinase/protein kinase B pathway. In conclusion, an integrative data acquisition strategy was used to characterize the C. elegans lipidome, providing valuable biological insights into hypothesis generation and validation.

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Multiple data acquisitions were used to profile the lipidome of C. elegans.

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940 detected lipids of 20 main classes involved in various pathways.

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Relevant hypotheses were generated using high-coverable lipidomics and pathways analysis.

Long-term exposure to polystyrene nanoparticles causes transgenerational toxicity by affecting the function and expression of MEV-1 and DAF-2 signals in Caenorhabditis elegans

In this study, we determined the roles of oxidative stress and related signals in mediating transgenerational toxicity of 30 nm polystyrene nanoparticles (PS-NPs) in Caenorhabditis elegans. Using brood size and locomotion behavior as endpoints, exposure to 1-100 μg/L PS-NPs caused transgenerational toxicity. Meanwhile, the activation of reactive oxygen species (ROS) was also observed transgenerationally after exposure to 1-100 μg/L PS-NPs. After exposure to 1 μg/L PS-NPs, the transgenerational toxicity was monitored until F2 generation (F2-G) and recovered at F3-G. At the F1-G of 1 μg/L PS-NPs-exposed nematodes, RNAi knockdown of daf-2 with function to inhibit oxidative stress suppressed the transgenerational toxicity and increased the mitochondrial SOD-3 expression. In contrast, at F3-G of 1 μg/L PS-NPs-exposed nematodes, RNAi knockdown of mev-1 with function to induce oxidative stress promoted locomotion and brood size, and suppressed the SOD-3 expression. Moreover, we observed the dynamic expressions of mev-1, daf-2, and sod-2 transgenerationally after exposure to 1 μg/L PS-NPs at P0-G, which further suggested the involvement of MEV-1, DAF-2, and SOD-3 in affecting induction of transgenerational PS-NP toxicity. Therefore, we provided the evidence to suggest the roles of oxidative stress activation and related molecular signals in mediating induction of transgenerational PS-NP toxicity. Our data highlights the crucial function of oxidative stress-related signals during induction of transgenerational PS-NP toxicity.

Microplastics and Their Impact on Reproduction-Can we Learn From the C. elegans Model?

Biologically active environmental pollutants have significant impact on ecosystems, wildlife, and human health. Microplastic (MP) and nanoplastic (NP) particles are pollutants that are present in the terrestrial and aquatic ecosystems at virtually every level of the food chain. Moreover, recently, airborne microplastic particles have been shown to reach and potentially damage respiratory systems. Microplastics and nanoplastics have been shown to cause increased oxidative stress, inflammation, altered metabolism leading to cellular damage, which ultimately affects tissue and organismal homeostasis in numerous animal species and human cells. However, the full impact of these plastic particles on living organisms is not completely understood. The ability of MPs/NPs to carry contaminants, toxic chemicals, pesticides, and bioactive compounds, such as endocrine disrupting chemicals, present an additional risk to animal and human health. This review will discusses the current knowledge on pathways by which microplastic and nanoplastic particles impact reproduction and reproductive behaviors from the level of the whole organism down to plastics-induced cellular defects, while also identifying gaps in current knowledge regarding mechanisms of action. Furthermore, we suggest that the nematode Caenorhabditis elegans provides an advantageous high-throughput model system for determining the effect of plastic particles on animal reproduction, using reproductive behavioral end points and cellular readouts.

Lipidome reveals the alleviation of krill oil on the impairment of acrylamide

Krill oil has rich content of polyunsaturated fatty acids and various biological functions. Previous researches have demonstrated that krill oil is helpful to improve the locomotion via antioxidation and regulation...

Metabolomics reveals the impact of saturation of dietary lipids on aging and longevity of C. elegans

Saturation differences in dietary lipids modify their digestive and absorption profiles, endpoints that may influence the nutrition and health. This study tests the hypothesis that dietary with elevated unsaturated fats...

The effect of krill oil on longevity and locomotion: a pilot study

Krill oil as a dietary supplement is popular with consumers. Several experimental and clinical trials have suggested that krill oil is beneficial for longevity and locomotion, but the underlying mechanisms for this have remained largely elusive. In this study, we investigated alleviation of impairment of Caenorhabditis elegans by polar compounds from frying oil with the use of krill oil. Observations of life span and locomotion demonstrated that the intake of krill oil increased median survival by 17.86%, head thrashes by 27.79% and body bends by 20.78% for impaired C. elegans. Metabolomic analysis revealed that krill oil could significantly restore the negative alterations caused by polar compounds, including upregulation of serine, tyrosine, palmitic acid and stearic acid, and downregulation of maltose 6'-phosphate, UDP-glucose, glutamic acid, phosphoserine and 25-hydroxyvitamin D3. Additionally, intake of krill oil also changed some metabolites that were irrelevant to impairment by polar compounds, but were beneficial for health for C. elegans. Metabolomics investigations indicated that krill oil ameliorates energy metabolism and alleviates oxidative stress and excitotoxicity caused by polar compounds on C. elegans. The data obtained in this study will facilitate future functional studies of krill oil.

Neuronal Gα subunits required for the control of response to polystyrene nanoparticles in the range of μg/L in C. elegans

The aim of this study was to identify Gα proteins mediating function of neuronal G protein-coupled receptors (GPCRs) in controlling the response to polystyrene nanoparticles (PS-NPs). Caenorhabditis elegans was used as an animal model, and both gene expression and functional analysis were performed to identify the Gα proteins in controlling PS-NPs toxicity. In nematodes, exposure to PS-NPs (1-100 μg/L) significantly altered transcriptional expressions of some neuronal Gα genes, including gpa-5, gpa-10, gpa-11, gpa-15 gsa-1, egl-30, and goa-1. Among these 7 Gα genes, only neuronal RNAi knockdown of gsa-1, gpa-10, and goa-1 affected toxicity of PS-NPs in inducing ROS production and in decreasing locomotion behavior. Some neuronal GPCRs (such as GTR-1, DCAR-1, DOP-2, NPR-8, NPR-12, NPR-9, and DAF-37) functioned upstream of GOA-1, some neuronal GPCRs (such as DCAR-1, DOP-2, NPR-9, NPR-8, and DAF-37) functioned upstream of GSA-1, and some neuronal GPCRs (such as DOP-2, NPR-8, DAF-37, and DCAR-1) functioned upstream of GPA-10 to regulate the toxicity of PS-NPs. Moreover, GOA-1 acted upstream of MPK-1/ERK MAPK, JNK-1/JNK MAPK, DBL-1/TGF-β, and DAF-7/ TGF-β, GSA-1 functioned upstream of MPK-1/ERK MAPK, JNK-1/JNK MAPK, and DBL-1/TGF-β, and GPA-10 functioned upstream of GLB-1/Globin and DBL-1/TGF-β to control the PS-NPs toxicity. Therefore, neuronal Gα proteins of GOA-1, GSA-1, and GPA-10 functioned to transduce signals of multiple GPCRs to different downstream signaling pathways during the control of PS-NPs toxicity in nematodes. Our results provide clues for understanding the important function of GPCRs-Gα signaling cascade in the neurons in controlling response to nanoplastics in organisms.

Size-dependent transgenerational toxicity induced by nanoplastics in nematode Caenorhabditis elegans

Nanoplastic exposure can potentially cause the severe transgenerational toxicity in organisms. However, the transgenerational nanoplastic toxicity and the underlying mechanisms are still largely unclear. Using Caenorhabditis elegans as an animal model, we here compared the transgenerational toxicity of two sizes of polystyrene nanoparticles (PS-NPs, 20 and 100 nm). The nematodes were exposed to PS-NPs at the P0 generation, and from the F1 generation the nematodes were grown under the normal condition. Exposure to 20 nm PS-NPs resulted in more severe transgenerational toxicity than exposure to 100 nm PS-NPs. At the concentration of 100 μg/L, the toxicity of 20 nm PS-NPs on locomotion and reproduction was detected at the F1-F6 generations, whereas the toxicity of 100 nm PS-NPs could only be observed at the F1-F3 generations. The difference in transgeneration toxicity between PS-NPs (20 nm) and PS-NPs (100 nm) was associated with the difference in transgenerational activation of oxidative stress. Based on observations on SOD-3::GFP, HSP-6::GFP, and HSP-4::GFP expressions, PS-NPs (20 nm) and PS-NPs (100 nm) further induced different transgenerational responses of anti-oxidation, mt UPR, and ER UPR. Our data suggested that the induction of transgenerational toxicity of PS-NPs was size dependent in nematodes. The results are helpful for our understanding the cellular mechanisms for the induction of transgenerational nanoplastic toxicity in organisms.

Toxicity mechanisms of polystyrene microplastics in marine mussels revealed by high-coverage quantitative metabolomics using chemical isotope labeling liquid chromatography mass spectrometry

Marine microplastic has become an important environmental issue of global concern due to its wide distribution and harmful impacts. However, there is still insufficient information on the toxicity mechanism of microplastics to marine organisms. In this study, we developed and applied a high-coverage quantitative metabolomics technique to investigate the toxicity mechanisms of the polystyrene microspheres (micro-PS) on marine mussels (Mytilus coruscus). A total of 3599 metabolites were quantified, including 163 positively identified metabolites, 318 high-confident putatively identified metabolites, and 2602 mass-matched metabolites from the hemolymph of mussels. Metabolomics analysis indicated that micro-PS disrupted the amino acid metabolism, particularly phenylalanine metabolism, which may lead to oxidative stress and neurotoxicity. Micro-PS at environmentally relevant concentrations induced oxidative stress and immunotoxicity in mussels. After 7 days of recovery, along with the significant clearance of micro-PS by mussels, both metabolite levels and biochemical indicators generally returned to the same level as the control group. Overall, the results showed that microplastics at environmentally-relevant concentrations can cause toxic effects on mussels but these influences are reversible. We envisage the usages of high-coverage metabolomics for investigating the toxicity of various types of microplastics under many different conditions, including those relevant to the marine environment.

Systematic toxicity evaluation of polystyrene nanoplastics on mice and molecular mechanism investigation about their internalization into Caco-2 cells

There is a growing concern regarding the toxic effects of nanoplastics (NPs) on aquatic and marine organism, while relatively few studies about their toxicity evaluation on mammals are conducted. In the present study, we observed accumulation of polystyrene NPs (PS NPs) in mice spleen, lung, kidney, small intestine, large intestine, testis, and brain after oral exposure to PS NPs (~100 nm, 10 mg/mL, 100 μL) for 28 days, and NPs were identified to induce cell apoptosis, inflammation, and structure disorder in these tissues. We also found that PS NPs could bring about hematological system injury and lipid metabolism disorder. Further in vitro studies identified that PS NPs could be absorbed by the intestinal epithelial Caco-2 cells by macropinocytosis and clathrin-mediated endocytosis, and induced disruption of tight junction between Caco-2 cells. Moreover, we found that it was easier for PS-NH₂ and PS-COOH to enter into Caco-2 cells, which may be associated with observed stronger toxicity of PS-NH₂ and PS-COOH NPs. In summary, this study demonstrated that NPs exposure brings about toxic effects to mice. This study could provide new insights regarding the distribution of NPs in humans, and helps us to evaluate the potential physiological risks of NPs to human beings.

Metabolomic Studies for the Evaluation of Toxicity Induced by Environmental Toxicants on Model Organisms

Environmental pollution causes significant toxicity to ecosystems. Thus, acquiring a deeper understanding of the concentration of environmental pollutants in ecosystems and, clarifying their potential toxicities is of great significance. Environmental metabolomics is a powerful technique in investigating the effects of pollutants on living organisms in the environment. In this review, we cover the different aspects of the environmental metabolomics approach, which allows the acquisition of reliable data. A step-by-step procedure from sample preparation to data interpretation is also discussed. Additionally, other factors, including model organisms and various types of emerging environmental toxicants are discussed. Moreover, we cover the considerations for successful environmental metabolomics as well as the identification of toxic effects based on data interpretation in combination with phenotype assays. Finally, the effects induced by various types of environmental toxicants in model organisms based on the application of environmental metabolomics are also discussed.

What Is on the Outside Matters-Surface Charge and Dissolve Organic Matter Association Affect the Toxicity and Physiological Mode of Action of Polystyrene Nanoplastics to C. elegans

To better understand nanoplastic effects, the potential for surface functionalization and dissolve organic matter eco-corona formation to modify the mechanisms of action and toxicity of different nanoplastics needs to be established. Here, we assess how different surface charges modifying functionalization (postive (+ve) aminated; neutral unfunctionalized; negative (-ve) carboxylated) altered the toxicity of 50 and 60 nm polystyrene nanoplastics to the nematode Caenorhabditis elegans. The potency for effects on survival, growth, and reproduction reduced in the order +ve aminated > neutral unfunctionalized ≫ -ve carboxylated with toxicity >60-fold higher for the +ve than -ve charged forms. Toxicokinetic-toxicodynamic modeling (DEBtox) showed that the charge-related potency was primarily linked to differences in effect thresholds and dose-associated damage parameters, rather than to toxicokinetic parameters. This suggests that surface functionalization may change the nature of nanoplastic interactions with membrane and organelles leading to variations in toxicity. Eco-corona formation reduced the toxicity of all nanoplastics indicating that organic molecule associations may passivate surfaces. Between particles, eco-corona interactions resulting in more equivalent effects; however, even despite these changes, the order of potency of the charged forms was retained. These results have important implications for the development of future grouping approaches.