Intratracheal administration of polystyrene microplastics induces pulmonary fibrosis by activating oxidative stress and Wnt/β-catenin signaling pathway in mice

A review on advancements in atmospheric microplastics research: The pivotal role of machine learning

Microplastics (MPs), recognized as emerging pollutants, pose significant potential impacts on the environment and human health. The investigation into atmospheric MPs is nascent due to the absence of effective characterization methods, leaving their concentration, distribution, sources, and impacts on human health largely undefined with evidence still emerging. This review compiles the latest literature on the sources, distribution, environmental behaviors, and toxicological effects of atmospheric MPs. It delves into the methodologies for source identification, distribution patterns, and the contemporary approaches to assess the toxicological effects of atmospheric MPs. Significantly, this review emphasizes the role of Machine Learning (ML) and Artificial Intelligence (AI) technologies as novel and promising tools in enhancing the precision and depth of research into atmospheric MPs, including but not limited to the spatiotemporal dynamics, source apportionment, and potential health impacts of atmospheric MPs. The integration of these advanced technologies facilitates a more nuanced understanding of MPs' behavior and effects, marking a pivotal advancement in the field. This review aims to deliver an in-depth view of atmospheric MPs, enhancing knowledge and awareness of their environmental and human health impacts. It calls upon scholars to focus on the research of atmospheric MPs based on new technologies of ML and AI, improving the database as well as offering fresh perspectives on this critical issue.

Lung microbiota participated in fibrous microplastics (MPs) aggravating OVA-induced asthma disease in mice

Environmental pollution is one of the risk factors for asthma. Currently, whether micro-plastics could aggravate asthma, is still unclear. In the air, fibrous MPs are the predominant shape. Since fibrous micro-plastics are reported to be detected in the lower respiratory tract and other body parts, the relationship of fibrous MP and asthma, as well as the potential mechanism is not well investigated. In this study, we produced fibrous MPs, whose lengths and widths were in accordance with the natural environment, and further, investigated the potential adverse effect of which on the asthma in a OVA (ovalbumin)-induced mice model, aiming at exploring the true life hazard of MP to the respiratory system. Following nasal exposure to fibrous MPs, the airway inflammation, mucus hypersecretion and fibrosis were aggravated in asthmatic mice. Fibrous MPs exposure also significantly increased the levels of total IgE, and, cardinal Th2 and Th1 pro-inflammatory cytokines participated in the etiopathogenesis of allergic airway inflammation. In addition, MP fibers exposure induced lung epithelial cells apoptosis, disruption of epithelial barrier integrity and activation of NLRP3 related signaling pathways. Moreover, fibrous MPs significantly altered the bacterial composition at the genus level. Compared to the control group, the relative abundance of Escherichia-Shigella and Uncultured were decreased to 4.47% and 0.15% in OVA group, while Blautia and Prevotella were elevated to 4.96% and 2.94%. For the OVA + MPs group, the relative abundance of Blautia and Uncultured were decreased to 2.27% and 0.006%, while Prevotella was increased to 3.05%. Our study highlights the detrimental effect of fibrous MPs on asthmatic population and facilitates an indication of the latent mechanisms of fibrous MPs induced airway pathology.

Polystyrene nanoplastics exposure causes erectile dysfunction in rats

Polystyrene nanoplastics (PS-NPs), emerging and increasingly pervasive environmental contaminants, have the potential to cause persistent harm to organisms. Although previous reports have documented local accumulation and adverse effects in a variety of major organs after PS-NPs exposure, the impact of PS-NPs exposure on erectile function remains unexplored. Herein, we established a rat model of oral exposure to 100 nm PS-NPs for 28 days. To determine the best dose range of PS-NPs, we designed both low-dose and high-dose PS-NPs groups, which correspond to the minimum and maximum human intake doses, respectively. The findings indicated that PS-NPs could accumulate within the corpus cavernosum and high dose but not low dose of PS-NPs triggered erectile dysfunction. Moreover, the toxicological effects of PS-NPs on erectile function include fibrosis in the corpus cavernous, endothelial dysfunction, reduction in testosterone levels, elevated oxidative stress and apoptosis. Overall, this study revealed that PS-NPs exposure can cause erectile dysfunction via multiple ways, which provided new insights into the toxicity of PS-NPs.

A metabolomics perspective on the effect of environmental micro and nanoplastics on living organisms: A review

The increasing trend regarding the use of plastics has arisen an exponential concern on the fate of their derived products to the environment. Among these derivatives, microplastics and nanoplastics (MNPs) have been featured for their associated environmental impact due to their low molecular size and high surface area, which has prompted their ubiquitous transference among all environmental interfaces. Due to the heterogenous chemical composition of MNPs, the study of these particles has focused a high number of studies, as a result of the myriad of associated physicochemical properties that contribute to the co-transference of a wide range of contaminants, thus becoming a major challenge for the scientific community. In this sense, both primary and secondary MNPs are well-known to be adscribed to industrial and urbanized areas, from which they are massively released to the environment through a multiscale level, involving the atmosphere, hydrosphere, and lithosphere. Consequently, much research has been conducted on the understanding of the interconnection between those interfaces, that motivate the spread of these contaminants to biological systems, being mostly represented by the biosphere, especially phytosphere and, finally, the anthroposphere. These findings have highlighted the potential hazardous risk for human health through different mechanisms from the environment, requiring a much deeper approach to define the real risk of MNPs exposure. As a result, there is a gap of knowledge regarding the environmental impact of MNPs from a high-throughput perspective. In this review, a metabolomics-based overview on the impact of MNPs to all environmental interfaces was proposed, considering this technology a highly valuable tool to decipher the real impact of MNPs on biological systems, thus opening a novel perspective on the study of these contaminants.

Microplastics in the human body: A comprehensive review of exposure, distribution, migration mechanisms, and toxicity

Microplastics (MPs) are pervasive across ecosystems, presenting substantial risks to human health. Developing a comprehensive review of MPs is crucial due to the growing evidence of their widespread presence and potential harmful effects. Despite the growth in research, considerable uncertainties persist regarding their transport dynamics, prevalence, toxicological impacts, and the potential long-term health effects they may cause. This review thoroughly evaluates recent advancements in research on MPs and their implications for human health, including estimations of human exposure through ingestion, inhalation, and skin contact. It also quantifies the distribution and accumulation of MPs in various organs and tissues. The review discusses the mechanisms enabling MPs to cross biological barriers and the role of particle size in their translocation. To ensure methodological rigor, this review adheres to the PRISMA guidelines, explicitly detailing the literature search strategy, inclusion criteria, and the quality assessment of selected studies. The review concludes that MPs pose significant toxicological risks, identifies critical gaps in current knowledge, and recommends future research directions to elucidate the prolonged effects of MPs on human health. This work aims to offer a scientific framework for mitigating MP-related hazards and establishes a foundation for ongoing investigation.

Polystyrene microplastics induce pulmonary fibrosis by promoting alveolar epithelial cell ferroptosis through cGAS/STING signaling

Polystyrene microplastics (PS-MPs) are new types of environmental pollutant that have garnered significant attention in recent years since they were found to cause damage to the human respiratory system when they are inhaled. The pulmonary fibrosis is one of the serious consequences of PS-MPs inhalation. However, the impact and underlying mechanisms of PS-MPs on pulmonary fibrosis are not clear. In this study, we studied the potential lung toxicity and PS-MPs-developed pulmonary fibrosis by long-term intranasal inhalation of PS-MPs. The results showed that after exposing to the PS-MPs, the lungs of model mouse had different levels of damage and fibrosis. Meanwhile, exposing to the PS-MPs resulted in a markedly decrease in glutathione (GSH), an increase in malondialdehyde (MDA), and iron overload in the lung tissue of mice and alveolar epithelial cells (AECs). These findings suggested the occurrence of PS-MP-induced ferroptosis. Inhibitor of ferroptosis (Fer-1) had alleviated the PS-MPs-induced ferroptosis. Mechanically, PS-MPs triggered cell ferroptosis and promoted the development of pulmonary fibrosis via activating the cGAS/STING signaling pathway. Inhibition of cGAS/STING with G150/H151 attenuated pulmonary fibrosis after PS-MPs exposure. Together, these data provided novel mechanistic insights of PS-MPs-induced pulmonary fibrosis and a potential therapeutic paradigm.

Microplastics dysregulate innate immunity in the SARS-CoV-2 infected lung

Introduction

Global microplastic (MP) pollution is now well recognized, with humans and animals consuming and inhaling MPs on a daily basis, with a growing body of concern surrounding the potential impacts on human health.

Methods

Using a mouse model of mild COVID-19, we describe herein the effects of azide-free 1 μm polystyrene MP beads, co-delivered into lungs with a SARS-CoV-2 omicron BA.5 inoculum. The effect of MPs on the host response to SARS-CoV-2 infection was analysed using histopathology and RNA-Seq at 2 and 6 days post-infection (dpi).

Results

Although infection reduced clearance of MPs from the lung, virus titres and viral RNA levels were not significantly affected by MPs, and overt MP-associated clinical or histopathological changes were not observed. However, RNA-Seq of infected lungs revealed that MP exposure suppressed innate immune responses at 2 dpi and increased pro-inflammatory signatures at 6 dpi. The cytokine profile at 6 dpi showed a significant correlation with the 'cytokine release syndrome' signature observed in some COVID-19 patients.

Discussion

The findings are consistent with the recent finding that MPs can inhibit phagocytosis of apoptotic cells via binding of Tim4. They also add to a growing body of literature suggesting that MPs can dysregulate inflammatory processes in specific disease settings.

Exposure to Environmental Toxins: Potential Implications for Stroke Risk via the Gut- and Lung-Brain Axis

Recent evidence indicates that exposure to environmental toxins, both short-term and long-term, can increase the risk of developing neurological disorders, including neurodegenerative diseases (i.e., Alzheimer's disease and other dementias) and acute brain injury (i.e., stroke). For stroke, the latest systematic analysis revealed that exposure to ambient particulate matter is the second most frequent stroke risk after high blood pressure. However, preclinical and clinical stroke investigations on the deleterious consequences of environmental pollutants are scarce. This review examines recent evidence of how environmental toxins, absorbed along the digestive tract or inhaled through the lungs, affect the host cellular response. We particularly address the consequences of environmental toxins on the immune response and the microbiome at the gut and lung barrier sites. Additionally, this review highlights findings showing the potential contribution of environmental toxins to an increased risk of stroke. A better understanding of the biological mechanisms underlying exposure to environmental toxins has the potential to mitigate stroke risk and other neurological disorders.

Microplastics and Oxidative Stress-Current Problems and Prospects

Microplastics (MPs) are plastic particles between 0.1 and 5000 µm in size that have attracted considerable attention from the scientific community and the general public, as they threaten the environment. Microplastics contribute to various harmful effects, including lipid peroxidation, DNA damage, activation of mitogen-activated protein kinase pathways, cell membrane breakages, mitochondrial dysfunction, lysosomal defects, inflammation, and apoptosis. They affect cells, tissues, organs, and overall health, potentially contributing to conditions like cancer and cardiovascular disease. They pose a significant danger due to their widespread occurrence in food. In recent years, information has emerged indicating that MPs can cause oxidative stress (OS), a known factor in accelerating the aging of organisms. This comprehensive evaluation exposed notable variability in the reported connection between MPs and OS. This work aims to provide a critical review of whether the harmfulness of plastic particles that constitute environmental contaminants may result from OS through a comprehensive analysis of recent research and existing scientific literature, as well as an assessment of the characteristics of MPs causing OS. Additionally, the article covers the analytical methodology used in this field. The conclusions of this review point to the necessity for further research into the effects of MPs on OS.

Mechanism of circRNA_SMG6 mediating lung macrophage ECM degradation via miR-570-3p in microplastics-induced emphysema

Microplastics (MPs) are plastic particles < 5 mm in diameter, of which polystyrene microplastics (PS-MPs) are representative type. The extracellular matrix (ECM) degradation of macrophages is associated with the development of emphysema. Additionally, circular RNAs (circRNAs) have a regulatory role in epigenetic mechanisms related to lung disease. However, the mechanisms of the ECM degradation and circRNAs in MPs-induced emphysema are still unclear. In our study, Sprague-Dawley (SD) rats were treated with 0, 0.5, 1.0 and 2.0 mg/m3 100 nm PS-MPs for 90 days in an inhalation experiment. PS-MPs-exposed rats showed elevated airway resistance and pulmonary dysfunction. Lung histopathology exhibited inflammatory cell infiltration, septal thickening and alveolar dilatation. Exposure to PS-MPs was able to induce elevated levels of ECM degradation-related markers MMP9 and MMP12, as well as reduced levels of elastin in rat lung tissues. CircRNA_SMG6 is a non-coding RNA (ncRNA) with a homologous circular structure in human, rat and mouse. The expression level of circRNA_SMG6 was decreased in both rat lung tissues exposed to PS-MPs and PS-MPs-treated THP-1 cells. The luciferase reporter gene demonstrated that circRNA_SMG6 combined with miR-570-3p and co-regulated PTEN, the target gene of miR-570-3p. Moreover, overexpression of circRNA_SMG6 or inhibition of miR-570-3p attenuated PS-MPs-induced ECM degradation in THP-1 cells. Taken together, circRNA_SMG6 may have a significant function in the deterioration of emphysema caused by PS-MPs-induced macrophage ECM degradation by regulating miR-570-3p. Our findings reveal a novel mechanism of emphysema caused by PS-MPs and provide valuable information for assessing the health risks of MPs.

Toxicological effects of microplastics in renal ischemia-reperfusion injury

The widespread presence of microplastics (MPs) in the environment poses a significant threat to biological survival and human health. However, our understanding of the toxic effects of MPs on the kidneys remains limited. This study aimed to investigate the underlying mechanism of the toxic effects of MPs on the kidneys using an ischemia-reperfusion (IR) mouse model. Four-week-old ICR mice were exposed to 0.5 μm MPs for 12 weeks prior to IR injury. The results showed that MPs exposure could aggravate the IR-induced damage to renal tubules and glomeruli. Although there were no significant changes in blood urea nitrogen and serum creatinine levels 7 days after IR, MPs treatment resulted in a slight increase in both parameters. In addition, the expression levels of inflammatory factors (MCP-1 and IL-6) at the mRNA level, as well as macrophage markers (CD68 and F4/80), were significantly higher in the MPs + IR group than in the Sham group after IR. Furthermore, MPs exposure exacerbated IR-induced renal fibrosis. Importantly, the expression of pyroptosis-related genes, including NLRP3, ASC, GSDMD, cleaved caspase-1, and IL-18, was significantly upregulated by MPs, indicating that MPs exacerbate pyroptosis in the context of renal IR. In conclusion, our findings suggest that MPs exposure can aggravate renal IR-induced pyroptosis by activating NLRP3-GSDMD signaling.

Pulmonary toxicity assessment of polypropylene, polystyrene, and polyethylene microplastic fragments in mice

Polypropylene (PP), polystyrene (PS), and polyethylene (PE) plastics are commonly used in household items such as electronic housings, food packaging, bottles, bags, toys, and roofing membranes. The presence of inhalable microplastics in indoor air has become a topic of concern as many people spent extended periods of time indoors during the COVID-19 pandemic lockdown restrictions, however, the toxic effects on the respiratory system are not properly understood. We examined the toxicity of PP, PS, and PE microplastic fragments in the pulmonary system of C57BL/6 mice. For 14 days, mice were intratracheally instilled 5 mg/kg PP, PS, and PE daily. The number of inflammatory cells such as macrophages, neutrophils, and eosinophils in the bronchoalveolar lavage fluid (BALF) of PS-instilled mice was significantly higher than that in the vehicle control (VC). The levels of inflammatory cytokines and chemokines in BALF of PS-instilled mice increased compared to the VC. However, the inflammatory responses in PP- and PE-stimulated mice were not significantly different from those in the VC group. We observed elevated protein levels of toll-like receptor (TLR) 2 in the lung tissue of PP-instilled mice and TLR4 in the lung tissue of PS-instilled mice compared with those to the VC, while TLR1, TLR5, and TLR6 protein levels remained unchanged. Phosphorylation of nuclear factor kappa B (NF-κB) and IĸB-α increased significantly in PS-instilled mice compared with that in VC. Furthermore, Nucleotide‑binding oligomerization domain‑like receptor family pyrin domain‑containing 3 (NLRP3) inflammasome components including NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and Caspase-1 in the lung tissue of PS-instilled mice increased compared with that in the VC, but not in PP- and PE-instilled mice. These results suggest that PS microplastic fragment stimulation induces pulmonary inflammation due to NF-ĸB and NLRP3 inflammasome activation by the TLR4 pathway.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43188-023-00224-x.

Unraveling the micro- and nanoplastic predicament: A human-centric insight

Micro- and nanoplastics are vast anthropogenic pollutants in our direct surroundings with a robust environmental stability and a potential for a long-lasting and increasing global circulation. This has raised concerns among the public and policy makers for human health upon exposure to these particles. The micro- and nanoplastic burden on humans is currently under debate, along with criticism on the experimental approaches used in hazard assessment. The present review presents an overview of the human-relevant aspects associated with the current micro-and nanoplastic burden. We focus on environmental circulation and the estimation of exposure quantities to humans, along with a state-of-the-art overview of particle accumulation in over 15 human organs and other specimen. Additionally, data regarding particle characteristics used in toxicity testing was extracted from 91 studies and discussed considering their environmental and human relevance.

Micro- and nano-plastics in the atmosphere: A review of occurrence, properties and human health risks

The ubiquitous occurrence of micro/nano plastics (MNPs) poses potential threats to ecosystem and human health that have attracted broad concerns in recent decades. Detection of MNPs in several remote regions has implicated atmospheric transport as an important pathway for global dissemination of MNPs and hence as a global health risk. In this review, the latest research progress on (1) sampling and detection; (2) origin and characteristics; and (3) transport and fate of atmospheric MNPs was summarized. Further, the current status of exposure risks and toxicological effects from inhaled atmospheric MNPs on human health is examined. Due to limitations in sampling and identification methodologies, the study of atmospheric nanoplastics is very limited today. The large spatial variation of atmospheric MNP concentrations reported worldwide makes it difficult to compare the overall indoor and outdoor exposure risks. Several in vitro, in vivo, and epidemiological studies demonstrate adverse effects of immune response, apoptosis and oxidative stress caused by MNP inhalation that may induce cardiovascular diseases and reproductive and developmental abnormalities. Given the emerging importance of atmospheric MNPs, the establishment of standardized sampling-pretreatment-detection protocols and comprehensive toxicological studies are critical to advance environmental and health risk assessments of atmospheric MNPs.

Systematic review of microplastics and nanoplastics in indoor and outdoor air: identifying a framework and data needs for quantifying human inhalation exposures

BACKGROUND

Humans are likely exposed to microplastics (MPs) in a variety of places including indoor and outdoor air. Research to better understand how exposure to MPs correlates to health is growing. To fully understand the possible impacts of MPs on human health, it is necessary to quantify MP exposure and identify what critical data gaps exist.

OBJECTIVES

The current paper provides a human exposure assessment of microplastics in the air using systematically reviewed literature that provided concentration of MPs in air as well as doses used in toxicology studies to calculate inhalation exposure dose.

METHODS

All published peer-reviewed journal articles, non-published papers, and grey literature that focused on micro- or nano-plastics in indoor and outdoor air were systematically searched using PRISMA guidelines. Literature that defined specific concentrations and size of MPs in air or exposed to human lung cells, animals, or humans with measurable health impacts were included in data extraction. Inhalational exposures were calculated for different age groups using published MP concentrations from the included literature using exposure dose equations and values from U.S. ATSDR and EPA.

RESULTS

Calculated mean indoor inhalational exposures from passive sampling methods were higher than those calculated from active sampling methods. When comparing indoor and outdoor sampling, calculated inhalation exposures from indoor samples were greater than those from outdoor samples. Inhalation exposures of MPs differed between age groups with infants having the highest calculated dose values for all locations followed by preschool age children, middle-school aged children, pregnant women, adolescents, and non-pregnant adults. MP doses used in toxicology studies produced higher calculated mean inhalational exposures than those from environmental samples.

IMPACT

This study is the first known systematic review of inhalational MP exposure from indoor and outdoor air. It also provides inhalational exposures calculated from previously published environmental samples of MPs as well as from toxicology studies.

Polystyrene microplastics induced disturbances in neuronal arborization and dendritic spine density in mice prefrontal cortex

An increasing use of plastics in daily life leads to the accumulation of microplastics (MPs) in the environment, posing a serious threat to the ecosystem, including humans. It has been reported that MPs cause neurotoxicity, but the deleterious effect of polystyrene (PS) MPs on neuronal cytoarchitectural morphology in the prefrontal cortex (PFC) region of mice brain remains to be established. In the present study, Swiss albino male mice were orally exposed to 0.1, 1, and 10 ppm PS-MPs for 28 days. After exposure, we found a significant accumulation of PS-MPs with a decreased number of Nissl bodies in the PFC region of the entire treated group compared to the control. Morphometric analysis in the PFC neurons using Golgi-Cox staining accompanied by Sholl analysis showed a significant reduction in basal dendritic length, dendritic intersections, nodes, and number of intersections at seventh branch order in PFC neurons of 1 ppm treated PS-MPs. In neurons of 0.1 ppm treated mice, we found only decrease in the number of intersections at the seventh branch order. While 10 ppm treated neurons decreased in basal dendritic length, dendritic intersections, followed by the number of intersections at the third and seventh branch order were observed. As well, spine density on the apical secondary branches along with mRNA level of BDNF was significantly reduced in all the PS-MPs treated PFC neurons, mainly at 1 ppm versus control. These results suggest that PS-MPs exposure affects overall basal neuronal arborization, with the highest levels at 1 and 10 ppm, followed by 0.1 ppm treated neurons, which may be related to the down-regulation of BDNF expression in PFC.

The potential toxicity of microplastics on human health

Microplastics are plastic particles, films, and fibers with a diameter of < 5 mm. Given their long-standing existence in the environment and terrible increase in annual emissions, concerns were raised about the potential health risk of microplastics on human beings. In particular, the increased consumption of masks during the COVID-19 pandemic has dramatically increased human contact with microplastics. To date, the emergence of microplastics in the human body, such as feces, blood, placenta, lower airway, and lungs, has been reported. Related toxicological investigations of microplastics were gradually increased. To comprehensively illuminate the interplay of microplastic exposure and human health, we systematically reviewed the updated toxicological data of microplastics and summarized their mode of action, adverse effects, and toxic mechanisms. The emerging critical issues in the current toxicological investigations were proposed and discussed. Our work would facilitate a better understanding of MPs-induced health hazards for toxicological evaluation and provide helpful information for regulatory decisions.

Size-dependent toxicity of polystyrene microplastics on the gastrointestinal tract: Oxidative stress related-DNA damage and potential carcinogenicity

Microplastics (MPs) and nanoplastics (NPs) have been generally regarded as emerging pollutants and received worldwide attention in recent years. Water and food consumption are the primary pathways for human exposure to MPs/NPs, thus gastrointestinal tracts may be susceptible to their toxicity. Although the recent report has indicated the presence of MPs/NPs in multiple human organs, little is known about their gastric effects. Therefore, this study focused on the adverse effects of polystyrene microplastics (PS-MPs) on gastric epithelium in vivo and in vitro. Surface-enhanced Raman spectroscopy (SERS) revealed the distribution of PS-MPs was associated with their particle sizes, and predominantly concentrated in gastric tissues. Gastric barrier injury and mitochondrial damage were observed in rats after exposure to PS-MPs. Compared with the larger ones, polystyrene nanoplastics (PS-NPs) more significantly reduced the activity of antioxidant enzymes while enhancing the level of MDA, 8-OhdG and γ-H2AX. Meanwhile, PS-MPs caused upregulation of β-catenin/YAP through redox-dependent regulation of nucleoredoxin (NXN) and dishevelled (Dvl). These findings supported the size-dependent effects of PS-MPs on oxidative stress and DNA damage. Moreover, the redox-dependent activation of the β-catenin/YAP cascade suggested a novel toxic mechanism for PS-MPs and implied the potential carcinogenic effects.

Pyrolysis temperature matters: Biochar-derived dissolved organic matter modulates aging behavior and biotoxicity of microplastics

Microplastics (MPs) have emerged as a novel and highly concerning contaminant that is ubiquitous in the aqueous environment. However, the aging of MPs induced by dissolved organic matter (DOM), especially biochar-derived dissolved organic matter (BDOM), and the biological toxicity after aging are not fully understood. In this study, the effects of biochar-derived BDOMs on the photoaging and biotoxicity of MPs were investigated at different pyrolysis temperatures using micro-scale polyethylene (PE) as an example. The results showed that the amount of ·OH generated by the BDOM/PE systems was related to the molecular composition and structure of BDOMs. High temperature BDOM7/9 with less lignin-like (34.33 % / 41.80 %) and more lipid (24.58 % / 19.88 %) content could produce more ·OH by itself, and its binding ability with PE was weaker due to its less hydrophobic components (SUVA260 = 0.10 / 0.11), which resulted in a weaker shading effect and less inhibition of the system, thus resulting in more ·OH production in the high temperature BDOM7/9/PE system. However, the involvement of BDOM, although favoring the long-term stable ·OH production of the system, did not significantly promote the photoaging of MPs. Furthermore, combined in vivo and in vitro biotoxicity studies of MPs showed that photoaging PE with the involvement of BDOM greatly improved systemic inflammation and tissue damage, as well as reactive oxygen species (ROS, such as ·OH and -OH)-induced cell death. For example, the addition of BDOM5/PE-light reduced the cell death of human lung, liver, and kidney cells from 54.70 %, 69.39 %, and 48.35 % to 22.78 %, 33.13 %, and 25.83 %, respectively, compared to the PE-light group. The results of this study contribute to an in-depth understanding of the environmental behavior of BDOM and MPs systems.

Airborne Nanoplastics Exposure Inducing Irreversible Glucose Increase and Complete Hepatic Insulin Resistance

As an emerging type of pollutant, microplastics have become a global environmental problem. Approximately, a fifth of the global burden of type 2 diabetes can be attributed to air particulate pollution. However, scientific knowledge remains limited about the effects of airborne nanoplastics (NPs) exposure on metabolic diseases. In this experiment, a whole-body exposure system was used to simulate the real atmospheric environment, and three exposure concentrations combined with the actual environmental concentration were selected to explore the effects of airborne NPs on metabolic diseases. Based on histological analyses, metabolic studies, gene expression, metabolites, and molecular signaling analyses, mice exposed to airborne NPs were observed to show a phenotype of systemic inflammation and complete insulin resistance featuring excessive drinking and eating, weight loss, elevated blood glucose, and decreased triglyceride levels. After airborne NPs exposure, mice were intolerant to glucose and tolerant to insulin. In addition, airborne NPs exposure could result in long-term irreversible hyperglycemia. Together, the research findings provide a strong basis for understanding the hazards of airborne nanopollution on metabolic disorders.

Therapeutic potential of melatonin in targeting molecular pathways of organ fibrosis

Fibrosis, the excessive deposition of fibrous connective tissue in an organ in response to injury, is a pathological condition affecting many individuals worldwide. Fibrosis causes the failure of tissue function and is largely irreversible as the disease progresses. Pharmacologic treatment options for organ fibrosis are limited, but studies suggest that antioxidants, particularly melatonin, can aid in preventing and controlling fibrotic damage to the organs. Melatonin, an indole nocturnally released from the pineal gland, is commonly used to regulate circadian and seasonal biological rhythms and is indicated for treating sleep disorders. While it is often effective in treating sleep disorders, melatonin's anti-inflammatory and antioxidant properties also make it a promising molecule for treating other disorders such as organ fibrosis. Melatonin ameliorates the necrotic and apoptotic changes that lead to fibrosis in various organs including the heart, liver, lung, and kidney. Moreover, melatonin reduces the infiltration of inflammatory cells during fibrosis development. This article outlines the protective effects of melatonin against fibrosis, including its safety and potential therapeutic effects. The goal of this article is to provide a summary of data accumulated to date and to encourage further experimentation with melatonin and increase its use as an anti-fibrotic agent in clinical settings.

Microplastics induced inflammation in the spleen of developmental Japanese quail (Coturnix japonica) via ROS-mediated p38 MAPK and TNF signaling pathway activation1

Microplastics (MPs) have been found in virtually every environment on earth and become a source of pollution around the world. The toxicology of microplastics on immunity is an emerging area of research, and more studies are needed to fully understand the effects of microplastics exposure on animal health. Therefore, we tried to determine the immunotoxic effects of microplastics on avian spleen by using an animal model- Japanese quail (Coturnix japonica). One-week chicks were exposed to environmentally relevant concentrations of 0.02 mg/kg, 0.4 mg/kg and 8 mg/kg polystyrene microplastics in the feed for 5 weeks. The results demonstrated that microplastics induced microstructural injuries featured by cell disarrangement and vacuolation indicating splenic inflammation. Ultrastructural damages including membrane lysis and mitochondrial vacuolation also suggested inflammatory responses in the spleen by microplastics exposure. Meanwhile, increasing reactive oxygen species (ROS) and Malondialdehyde (MDA) while the inactivation of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) indicated oxidative stress in the spleen. Moreover, the increasing level of proinflammatory cytokines including Tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin-1β (IL-1β), interleukin-6 (IL-6) and decreasing level of anti-inflammatory cytokine interleukin-10 (IL-10) implied splenic inflammation. Furthermore, transcriptomic analysis showed that microplastics induced inflammatory responses in the spleen through p38 mitogen-activated protein kinases (p38 MAPK) pathway activation and tumor necrosis factor (TNF) signaling stimulation. The signaling stimulation also aggravated cell apoptosis in the spleen. The present study may benefit to understand potential mechanisms of developmental immunotoxicology of microplastics.

Airborne microplastics: A narrative review of potential effects on the human respiratory system

There has been growing evidence showing the widespread of airborne microplastics (AMPs) in many regions of the world, raising concerns about their impact on human health. This review aimed to consolidate recent literature on AMPs regarding their physical and chemical characteristics, deposition in the human respiratory tract, translocation, occurrence from human studies, and toxic effects determined in vitro and in vivo. The physical characteristics influence interactions with cell membranes, cellular internalization, accumulation, and cytotoxicity resulting from cell membrane damage and oxidative stress. In addition, prolonged exposure to AMP-associated toxic chemicals might lead to significant health effects. Most toxicological assessments of AMPs in vitro and in vivo have demonstrated that oxidative stress and inflammation are major mechanisms of action for their toxic effects. Elevated reactive oxygen species production could lead to mitochondrial dysfunction, inflammatory responses, and subsequent apoptosis in experimental models. To date, there has been some evidence suggesting exposure in humans. However, the data are still insufficient, and adverse human health effects need to be investigated. Future research on the existence, exposure, and health effects of AMPs is required for developing preventive and mitigation measures to protect human health.

Recent progress of microplastic toxicity on human exposure base on in vitro and in vivo studies

Microplastics are widely distributed in the environment, including the atmosphere, soil and water bodies. They have been found to have toxic effects on organisms. The impact on human health is also receiving considerable attention. Microplastics can be found in drinking water, food, air and plastic products, and they can enter human body through the pathways such as ingestion, inhalation, and skin contact. After exposure to microplastics, they can induce cellular toxicity and produce toxic effects on multiple organs and systems, including the digestive, respiratory, nervous, reproductive and cardiovascular systems. This paper presents a comprehensive review and analysis on the recent progress of human exposure studies, in vitro experiments, rodent experiments, and other model experiments in microplastic human toxicity research. It comprehensively analyzes the potential human toxic effects of microplastics, providing a theoretical basis for further research on microplastic human toxicity and its mechanisms. Furthermore, this paper highlights the knowledge gaps and provides the recommendations for future research on human toxicity of microplastics.

A systematic review of the impacts of exposure to micro- and nano-plastics on human tissue accumulation and health

Micro- and nano-plastics (MNPs) pollution has become a pressing global environmental issue, with growing concerns regarding its impact on human health. However, evidence on the effects of MNPs on human health remains limited. This paper reviews the three routes of human exposure to MNPs, which include ingestion, inhalation, and dermal contact. It further discusses the potential routes of translocation of MNPs in human lungs, intestines, and skin, analyses the potential impact of MNPs on the homeostasis of human organ systems, and provides an outlook on future research priorities for MNPs in human health. There is growing evidence that MNPs are present in human tissues or fluids. Lab studies, including in vivo animal models and in vitro human-derived cell cultures, revealed that MNPs exposure could negatively affect human health. MNPs exposure could cause oxidative stress, cytotoxicity, disruption of internal barriers like the intestinal, the air-blood and the placental barrier, tissue damage, as well as immune homeostasis imbalance, endocrine disruption, and reproductive and developmental toxicity. Limitedly available epidemiological studies suggest that disorders like lung nodules, asthma, and blood thrombus might be caused or exacerbated by MNPs exposure. However, direct evidence for the effects of MNPs on human health is still scarce, and future research in this area is needed to provide quantitative support for assessing the risk of MNPs to human health.

Biomarkers of oxidative stress, inflammation, and genotoxicity to assess exposure to micro- and nanoplastics. A literature review

The increased awareness about possible health effects arising from micro- and nanoplastics (MNPs) pollution is driving a huge amount of studies. Many international efforts are in place to better understand and characterize the hazard of MNPs present in the environment. The literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology in two different databases (PubMed and Embase). The selection of articles was carried out blind, screening titles and abstracts according to inclusion and exclusion criteria. In general, these studies rely on the methodology already in use for assessing hazard from nanomaterials and particles of concern. However, only a limited number of studies have so far directly measured human exposure to MNPs and examined the relationship between such exposure and its impact on human health. This review aims to provide an overview of the current state of research on biomarkers of oxidative stress, inflammation, and genotoxicity that have been explored in relation to MNPs exposure, using human, cellular, animal, and plant models. Both in-vitro and in-vivo models suggest an increased level of oxidative stress and inflammation as the main mechanism of action (MOA) leading to adverse effects such as chronic inflammation, immunotoxicity and genotoxicity. With the identification of such biological endpoints, representing critical key initiating events (KIEs) towards adaptive or adverse outcomes, it is possible to identify a panel of surrogate biomarkers to be applied and validated especially in occupational settings, where higher levels of exposure may occur.

Research progress on the cellular toxicity caused by microplastics and nanoplastics

Microplastics (MPs) are plastic particles of a diameter of less than 5 mm and a major carrier of pollution. In accordance with its diameter range, MPs can be divided into microplastics (100-5 mm) and nanoplastics (<100 nm). In recent years, in addition to the impact of MPs on the environment, the ways in which MPs affect the body has also attracted continuous attention. However, relevant studies on the cytotoxicity of MPs are not comprehensive. Based on the current research, this paper summarizes four main cytotoxic mechanisms of MPs, inducing oxidative stress, damaging cell membrane organelles, inducing immune response, and genotoxicity. Generally, MPs cause cytotoxicity such as oxidative stress, damage to cell membranes and organelles, activation of immune responses, and genotoxicity through mechanical damage or induction of cells to produce reactive oxygen species. Understanding these toxic mechanisms is helpful for the evaluation and prevention of human toxicity of MPs. This paper also analyzes the limitations of current research and prospects for future research into cellular MPs, with the aim of providing a scientific basis and reference for further research into the toxic mechanism of MPs.

Assessing micro and nanoplastics toxicity using rodent models: Investigating potential mitochondrial implications

Mitochondria's role as a central hub in cellular metabolism and signaling cascades is well established in the scientific community, being a classic marker of organisms' response to toxicant exposure. Nonetheless, little is known concerning the effects of emerging contaminants, such as microplastics, on mitochondrial metabolism. Micro- and nanoplastics present one of the major problems faced by modern societies. What was once an environmental problem is now recognized as an one-health issue, but little is known concerning microplastic impact on human health. Indeed, only recently, human exposure to microplastics was acknowledged by the World Health Organization, resulting in a growing interest in this research topic. Nonetheless, the mechanisms behind micro- and nanoplastics toxicity are yet to be understood. Animal models, nowadays, are the most appropriate approach to uncovering this knowledge gap. In the present review article, we explore investigations from the last two years using rodent models and reach to find the molecular mechanism behind micro- and nanoplastics toxicity and if mitochondria can act as a target. Although no research article has addressed the effects of mitochondria yet, reports have highlighted molecular and biochemical alterations that could be linked to mitochondrial function. Furthermore, certain studies described the effects of disruptions in mitochondrial metabolism, such as oxidative stress. Micro- and nanoplastics may, directly and indirectly, affect this vital organelle. Investigations concerning this topic should be encouraged once they can bring us closer to understanding the mechanisms underlying these particles' harmful effects on human health.

Apoptotic bodies of bone marrow mesenchymal stem cells inhibit endometrial stromal cell fibrosis by mediating the Wnt/β-catenin signaling pathway

Background

Intrauterine adhesions (IUAs) are a common illness of the uterine cavity. Endometrial fibrosis is the main pathological feature. In addition to a high recurrence rate, patients with severe IUAs have a low pregnancy rate. However, there are few effective treatments for IUAs. This study aims to confirm the influence of apoptotic bodies of bone marrow mesenchymal stem cells (BMSCs) on endometrial stromal cell fibrosis by mediating the Wnt/β-catenin signaling pathway and to provide new insight for the clinical treatment of IUAs.

Methods

Human endometrial stromal cells (HESCs) were used to establish an IUA cell model by treatment with TGF-β1, and a rat IUA model was established by the double injury method. Apoptosis of BMSCs was detected by TUNEL assays, and cell morphology was observed by the CM-DiI tracer. The morphology of apoptotic vacuoles and apoptotic bodies (ABs) was detected by TEM. We used Western blotting to detect the expression of histone H3.3, histone H2B, C3b, cyclin D1, C1QC, α-SMA, COL1A1, COL5A2, FN, CTGF, Wnt2b, c-MYC, CK-18 and VIM. The expression levels of α-SMA, COL1A1, COL5A2, FN and CTGF were detected by RT‒qPCR. The expression levels of α-SMA, COL1A1, FN and CTGF were detected by immunofluorescence. Immunohistochemistry was used to detect the expression of TGF-β, CK-18 and VIM. Flow cytometry, cell scratch assays, CCK-8 assays, and H & E and Masson staining were used to detect the cell cycle, cell migration, cell proliferation, and endometrial pathology, respectively.

Results

We found that ultraviolet light (UV) irradiation induced apoptosis of BMSCs and increased the production of ABs. TGF-β1 treatment can induce HESCs to form extracellular matrix (ECM), and aggravate cell fibrosis, and adding ABs or FH535, an inhibitor of the Wnt/β-catenin signaling pathway, can inhibit TGF-β1-induced HESC fibrosis. However, the inhibitory effect of ABs on TGF-β1-induced fibrosis of HESCs was attenuated by the addition of LiCl. In the Wnt/β-catenin signaling pathway, LiCl is an activator after coculture with TGF-β1. In vivo, IUA-induced narrowing of the uterine cavity was accompanied by intrauterine adhesions, increased deposition of collagen fibers, upregulation of TGF-β1, VIM, α-SMA, COL1A1 and COL5A2, and downregulation of CK-18. These changes in expression were reversed after treatment with ABs or FH535. When ABs and LiCl were added at the same time, the inhibitory effect of ABs on IUA fibrosis was weakened.

Conclusion

BMSC-derived ABs inhibit the fibrosis of HESCs by inhibiting the Wnt/β-catenin signaling pathway. These results provide a new direction for the clinical treatment of IUAs.

Polytetrafluorethylene microplastic particles mediated oxidative stress, inflammation, and intracellular signaling pathway alteration in human derived cell lines

Microplastics (MPs) are now widely distributed across the aerial, terrestrial, and aquatic environments. Thus, exposure to MPs via the oral, inhalation, or dermal routes is inevitable. Polytetrafluoroethylene (PTFE)-MPs is mainly used for manufacturing nonstick cookware, semiconductors, and medical devices; however, their toxicity has been rarely studied. In the present study, six different human cell lines, which are representative of tissues and cells that directly or indirectly come into contact with MPs, were exposed to two different sizes of irregular shape PTFE-MPs (with an average diameter of 6.0 or 31.7 μm). PTFE-MPs-mediated cytotoxicity, oxidative stress, and changes in proinflammatory cytokine production were then evaluated. We found that the PTFE-MPs did not induce cytotoxicity under any of the experimental conditions. However, PTFE-MPs (especially average diameter of 6.0 μm) induced nitric oxide and reactive oxygen species production in all the cell lines tested. Moreover, both sizes of PTFE-MPs increased the secretion of tumor necrosis factor alpha and interleukin-6 from the U937 macrophage cell line and the A549 lung epithelial cell line, respectively. In addition, PTFE-MPs activated the MAPK signaling pathways, especially the ERK pathway, in A549 and U937 cells, and in the THP-1 dendritic cell line. We also found that the expression of the NLRP3 inflammasome was reduced in the U937 and THP-1 cell lines following treatment with the PTFE-MPs sized 31.7 μm average diameter. Furthermore, expression of the apoptosis regulator, BCL2, was markedly increased in the A549 and U937 cell lines. Thus, although PTFE-MPs exert different effects on different cell types, our findings suggest that PTFE-MPs-associated toxicity may be specifically linked to the activation of the ERK pathway, which ultimately induces oxidative stress and inflammation.

Micro- and nanoplastics (MNPs) and their potential toxicological outcomes: State of science, knowledge gaps and research needs

Plastic waste has been produced at a rapidly growing rate over the past several decades. The environmental impacts of plastic waste on marine and terrestrial ecosystems have been recognized for years. Recently, researchers found that micro- and nanoplastics (MNPs), micron (100 nm - 5 mm) and nanometer (1 - 100 nm) scale particles and fibers produced by degradation and fragmentation of plastic waste in the environment, have become an important emerging environmental and food chain contaminant with uncertain consequences for human health. This review provides a comprehensive summary of recent findings from studies of potential toxicity and adverse health impacts of MNPs in terrestrial mammals, including studies in both in vitro cellular and in vivo mammalian models. Also reviewed here are recently released biomonitoring studies that have characterized the bioaccumulation, biodistribution, and excretion of MNPs in humans. The majority MNPs in the environment to which humans are most likely to be exposed, are of irregular shapes, varied sizes, and mixed compositions, and are defined as secondary MNPs. However, the MNPs used in most toxicity studies to date were commercially available primary MNPs of polystyrene (PS), polyethylene (PE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and other polymers. The emerging in vitro and in vivo evidence reviewed here suggests that MNP toxicity and bioactivity are largely determined by MNP particle physico-chemical characteristics, including size, shape, polymer type, and surface properties. For human exposure, MNPs have been identified in human blood, urine, feces, and placenta, which pose potential health risks. The evidence to date suggests that the mechanisms underlying MNP toxicity at the cellular level are primarily driven by oxidative stress. Nonetheless, large knowledge gaps in our understanding of MNP toxicity and the potential health impacts of MNP exposures still exist and much further study is needed to bridge those gaps. This includes human population exposure studies to determine the environmentally relevant MNP polymers and exposure concentrations and durations for toxicity studies, as well as toxicity studies employing environmentally relevant MNPs, with surface chemistries and other physico-chemical properties consistent with MNP particles in the environment. It is especially important to obtain comprehensive toxicological data for these MNPs to understand the range and extent of potential adverse impacts of microplastic pollutants on humans and other organisms.

Melatonin Alleviates Intestinal Barrier Damaging Effects Induced by Polyethylene Microplastics in Albino Rats

There have been concerns about the potential health risks posed by microplastics (MP). The detection of MP in a variety of food products revealed that humans are ingesting MP. Nevertheless, there is a paucity of data about their impacts, as well as their uptake, on intestinal barrier integrity. This study examined the toxic effects of oral administration of two doses of polyethylene microplastics (PE-MP) (3.75 or 15 mg/kg/day for 5 weeks; mean particle size: 4.0-6.0 µm) on the intestinal barrier integrity in rats. Moreover, the effect of melatonin treatment with MP exposure was also assessed. The PE-MP particle uptake, histopathological changes, Alcian blue staining, Muc2 mRNA, proinflammatory cytokines (IL-1β and TNF-α), and cleaved caspase-3, as well as tight junction proteins (claudin-1, myosin light-chain kinase (MLCK), occludin, and zonula occludens-1 (ZO-1)) were assessed. Oral administration of PE-MP resulted in apparent jejunal histopathological alterations; significantly decreased mucin secretion, occludin, ZO-1, and claudin-1 expression; and significantly upregulated MLCK mRNA, IL-1β concentration, and cleaved caspase-3 expression. Melatonin reversed these altered parameters and improved the PE-MP-induced histopathological and ultrastructure changes. This study highlighted the PE-MP's toxic effect on intestinal barrier integrity and revealed the protective effect of melatonin.

The detrimental effects of micro-and nano-plastics on digestive system: An overview of oxidative stress-related adverse outcome pathway

With the massive manufacture and use of plastics, plastic pollution-related environmental impacts have raised great concern in recent years. As byproducts of plastic fragmentation and degradation, microplastics (MPs) and nanoplastics (NPs) have been identified as novel pollutants that posed a threat to the ecosystem and humans. Since MPs/NPs could be transported via the food chain and retained in the water, the digestive system should be one of the major targets of MPs/NPs-related toxicity. Although considerable evidence has supported the digestive toxicity of MPs/NPs, the proposed mechanisms remained ambiguous due to the variety of study types, models, and endpoints. This review provided a mechanism-based perspective on MPs/NPs-induced digestive effects by adopting the adverse outcome pathway framework as a promising tool. The overproduction of reactive oxygen species was identified as the molecular initiating event in MPs/NPs-mediated injury to the digestive system. A series of detrimental effects including oxidative stress, apoptosis, inflammation, dysbiosis, and metabolic disorders were summarized as key events. Finally, the occurrence of these effects eventually led to an adverse outcome, suggesting a possible increase in the incidence of digestive morbidity and mortality.

S1PR2/Wnt3a/RhoA/ROCK1/β-catenin signaling pathway promotes diabetic nephropathy by inducting endothelial mesenchymal transition and impairing endothelial barrier function

AIMS

Hyperglycemia and hyperlipidemia are key factors in the pathogenesis of diabetic nephropathy (DN), and renal fibrosis is the most common pathway leading to the disease. Endothelial mesenchymal transition (EndMT) is a crucial mechanism for the production of myofibroblasts, and impaired endothelial barrier function is one of the mechanisms for the generation of microalbuminuria in DN. However, the specific mechanisms behind these are not yet clear.

MAIN METHODS

Protein expression was detected by immunofluorescence, immunohistochemistry and Western blot. Knocking down or pharmacological inhibition of S1PR2 were used to inhibit Wnt3a, RhoA, ROCK1, β-catenin, and Snail signaling. Changes in cell function were analyzed by CCK-8 method, cell scratching assay, FITC-dextran permeability assay, and Evans blue staining.

KEY FINDINGS

Consistent with increased gene expression of S1PR2 in DN patients and mice with kidney fibrosis disease, S1PR2 expression was significantly increased in glomerular endothelial cells of DN mice and HUVEC cells treated with glucolipids. Knocking down or pharmacological inhibition of S1PR2 significantly decreased the expression of Wnt3a, RhoA, ROCK1, and β-catenin in endothelial cells. Furthermore, inhibition of S1PR2 in vivo reversed EndMT and endothelial barrier dysfunction in glomerular endothelial cells. Inhibition of S1PR2 and ROCK1 in vitro also reversed EndMT and endothelial barrier dysfunction in endothelial cells.

SIGNIFICANCE

Our results suggest that the S1PR2/Wnt3a/RhoA/ROCK1/β-catenin signaling pathway is involved in the pathogenesis of DN by inducing EndMT and endothelial barrier dysfunction.

Di(2-ethylhexyl) phthalate and microplastics cause necroptosis and apoptosis in hepatocytes of mice by inducing oxidative stress

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer and an endocrine disruptor. Microplastics (MPs) are pathogenic small plastic particles and abundant in the aqueous environment. The problem of residual hazards of plastic products is worthy of study, especially the joint exposure of a variety of plastic-related products to the toxic effect. We used 200 mg/kg DEHP and 10 mg/L MPs to establish exposure model in vivo and 2 mM DEHP and 200 μg/L MPs to establish AML12 cell exposure model in vitro. In vivo study results showed that compared with the control group (NC) group, DEHP and MPs significantly increased the contents of malondialdehyde and hydrogen peroxide, and significantly decreased the contents of glutathione and the activity of superoxide dismutase, total antioxidant capacity, catalase and glutathione peroxidase. The level of oxidative stress was further aggravated after combined exposure. The reactive oxygen species level of AML12 exposed to DEHP and MPs in vitro was significantly higher than NC group, and the combined exposure was significantly higher than the single exposure. The in vivo and in vitro also confirmed that DEHP and MPs could significantly increase the mRNA and protein levels of apoptosis markers and necroptosis markers and there was an additive effect. After N-acetylcysteine treatment in vitro, the above-mentioned oxidative stress level and cell damage decreased significantly. This study provided a reference for advocating the reduction of the mixed use of plastic products, and provided a basis for preventing the harm of plastic products residues.

Characterisation of changes in global genes expression in the lung of ICR mice in response to the inflammation and fibrosis induced by polystyrene nanoplastics inhalation

This study characterised the changes in global gene expression in the lung of ICR mice in response to the inflammation and fibrosis induced by the inhalation of 0.5 μm polystyrene (PS)-nanoplastics (NPs) at various concentrations (4, 8, and 16 μg/mL) for 2 weeks. The total RNA extracted from the lung tissue of NPs-inhaled mice was hybridised into oligonucleotide microarrays. Significant upregulation was detected in several inflammatory responses, including the number of immune cells in bronchoalveolar lavage fluid (BALF), the expression level of inflammatory cytokines, mucin secretion, and histopathological changes, while they accumulated average of 13.38 ± 1.0 μg/g in the lungs of the inhaled ICR mice. Similar responses were observed regarding the levels of fibrosis-related factors in the NPs-inhaled lung of ICR mice, such as pulmonary parenchymal area, expression of pro-fibrotic marker genes, and TGF-β1 downstream signalling without any significant hepatotoxicity and nephrotoxicity. In microarray analyses, 60 genes were upregulated, and 55 genes were downregulated in the lung of ICR mice during inflammation and fibrosis induced by NPs inhalation compared to the Vehicle-inhaled mice. Among these genes, many were categorised into several ontology categories, including the anatomical structure, binding, membrane, and metabolic process. Furthermore, the major genes in the upregulated categories included Igkv14-126000, Egr1, Scel, Lamb3, and Upk3b. In contrast, the major genes in the down-regulated categories were Olfr417, Olfr519, Rps16, Rap2b, and Vmn1r193. These results suggest several gene functional groups and individual genes as specific biomarkers respond to inflammation and fibrosis induced by PS-NPs inhalation in ICR mice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43188-023-00188-y.

Atmospheric microplastic and nanoplastic: The toxicological paradigm on the cellular system

The increasing demand for plastic in our daily lives has led to global plastic pollution. The improper disposal of plastic has resulted in a massive amount of atmospheric microplastics (MPs), which has further resulted in the production of atmospheric nanoplastics (NPs). Because of its intimate relationship with the environment and human health, microplastic and nanoplastic contamination is becoming a problem. Because microplastics and nanoplastics are microscopic and light, they may penetrate deep into the human lungs. Despite several studies demonstrating the abundance of microplastics and nanoplastics in the air, the potential risks of atmospheric microplastics and nanoplastics remain unknown. Because of its small size, atmospheric nanoplastic characterization has presented significant challenges. This paper describes sampling and characterization procedures for atmospheric microplastics and nanoplastics. This study also examines the numerous harmful effects of plastic particles on human health and other species. There is a significant void in research on the toxicity of airborne microplastics and nanoplastics upon inhalation, which has significant toxicological potential in the future. Further study is needed to determine the influence of microplastic and nanoplastic on pulmonary diseases.

Microplastics and Antibiotic Resistance: The Magnitude of the Problem and the Emerging Role of Hospital Wastewater

The role of microplastics (MPs) in the spread of antibiotic resistance genes (ARGs) is increasingly attracting global research attention due to their unique ecological and environmental effects. The ubiquitous use of plastics and their release into the environment by anthropic/industrial activities are the main sources for MP contamination, especially of water bodies. Because of their physical and chemical characteristics, MPs represent an ideal substrate for microbial colonization and formation of biofilm, where horizontal gene transfer is facilitated. In addition, the widespread and often injudicious use of antibiotics in various human activities leads to their release into the environment, mainly through wastewater. For these reasons, wastewater treatment plants, in particular hospital plants, are considered hotspots for the selection of ARGs and their diffusion in the environment. As a result, the interaction of MPs with drug-resistant bacteria and ARGs make them vectors for the transport and spread of ARGs and harmful microorganisms. Microplastic-associated antimicrobial resistance is an emerging threat to the environment and consequently for human health. More studies are required to better understand the interaction of these pollutants with the environment as well as to identify effective management systems to reduce the related risk.

The regulation of circRNA_kif26b on alveolar epithelial cell senescence via miR-346-3p is involved in microplastics-induced lung injuries

Microplastics (MPs), the emerging environmental contaminants, can be inhaled and lead to lung injuries, including inflammation and fibrosis. Alveolar epithelial cell senescence is associated with several lung diseases, but its mechanism in MPs-induced lung injuries remains unknown. In this study, polystyrene microplastics (PS-MPs) in the form of microspheres with a particle size of 100 nm were used for a 35-day inhalation exposure in SPF-grade Sprague-Dawley (SD) rats. The plethysmograph showed lung dysfunction. The hematoxylin and eosin (H&E) staining revealed lung histological lesions with a significant accumulation of inflammatory cells. The β-galactosidase staining indicated increased senescent cells in lung tissues. The ELISA suggested increased senescence-associated secretory phenotype (SASP) in bronchoalveolar lavage fluid (BALF). Treatment of mouse alveolar epithelial cell line MLE12 with PS-MPs raised levels of senescence-related markers p21, p16, and p27 and SASP secretion. circ_kif26b, a ring-structured non-coding RNA (ncRNA), is homologous in human, rat, and mouse and was elevated in PS-MPs-exposed rat lung tissues as well as in PS-MPs-treated MLE12 cells. The luciferase reporter gene revealed that circ_kif26b was bound to miR-346-3p and co-regulated p21, a target gene of miR-346-3p. circ_kif26b knockdown or miR-346-3p overexpression attenuated PS-MPs-induced MLE12 cell senescence and secretion of the SASP cytokines IL-6 and IL-8. However, down-regulation of circ_kif26b and miR-346-3p reversed this depressive effect. Overall, circ_kif26b mediates alveolar epithelial cell senescence through miR-346-3p and participates in PS-MPs-induced lung inflammation. These findings provide new insights into the mechanisms of MPs inhalation toxicity and lay a mechanistic foundation for health risk assessment of MPs.

Atmospheric microplastics: exposure, toxicity, and detrimental health effects

Microplastics (MPs) are micro-particulate pollutants present in all environments whose ubiquity leads humans to unavoidable exposure. Due to low density, MPs also accumulate in the atmosphere, where they are easily transported worldwide and come into direct contact with the human body by inhalation or ingestion, causing detrimental health effects. This literature review presents the sources of atmospheric MPs pollution, transport routes, physicochemical characteristics, and environmental interactions. The document also explains the implications for human health and analyzes the risk of exposure based on the potential toxicity and the concentration in the atmosphere. MPs' toxicity lies in their physical characteristics, chemical composition, environmental interactions, and degree of aging. The abundance and concentration of these microparticles are associated with nearby production sources and their displacement in the atmosphere. The above elements are presented in an integrated way to facilitate a better understanding of the associated risk. The investigation results encourage the development of future research that delves into the health implications of exposure to airborne MPs and raises awareness of the risks of current plastic pollution to promote the establishment of relevant mitigation policies and procedures.

Hyperoxia exposure upregulates Dvl-1 and activates Wnt/β-catenin signaling pathway in newborn rat lung

BACKGROUND

Bronchopulmonary dysplasia is a serious and lifelong pulmonary disease in premature neonates that influences around one-quarter of premature newborns. The wingless-related integration site /β-catenin signaling pathway, which is abnormally activated in the lungs with pulmonary fibrosis, affects cell differentiation and lung development.

METHODS

Newborn rats were subjected to hyperoxia exposure. Histopathological changes to the lungs were evaluated through immunohistochemistry, and the activation of disheveled and Wnt /β-catenin signaling pathway components was assessed by Western blotting and real-time PCR. The abilities of proliferation, apoptosis and migration were detected by Cell Counting Kit-8, flow cytometry and scratch wound assay, respectively.

RESULTS

Contrasting with normoxic lungs, hyperoxia-exposed lungs demonstrated larger alveoli, fewer alveoli and thicker alveolar septa. Superoxide dismutase activity was significantly decreased (7th day: P < 0.05; 14th day: P < 0.01) and malondialdehyde significantly increased (7th day: P < 0.05; 14th day: P < 0.01) after hyperoxia exposure. Protein and mRNA expression levels of β-catenin, Dvl-1, CTNNBL1 and cyclin D1 were significantly upregulated by hyperoxia exposure on 7th day (P < 0.01) and 14th day (P < 0.01). In hyperoxic conditions, Dvl-l downregulation and Dvl-l downregulation + MSAB treatment significantly increased the proliferation rates, decreased the apoptosis rates and improved the ability of cell migration. In hyperoxic conditions, Dvl-l downregulation could decrease the mRNA expression levels of GSK3β, β-catenin, CTNNBL1 and cyclin D1 and decrease the protein relative expression levels of GSK3β, p-GSK3β, β-catenin, CTNNBL1 and cyclin D1.

CONCLUSIONS

We confirmed the positive role of Dvl-1 and the Wnt/β-catenin signaling pathway in promoting BPD in hyperoxia conditions and provided a promising therapeutic target.

Microplastics: A Matter of the Heart (and Vascular System)

Plastic use dramatically increased over the past few years. Besides obvious benefits, the consequent plastic waste and mismanagement in disposal have caused ecological problems. Plastic abandoned in the environment is prone to segregation, leading to the generation of microplastics (MPs) and nanoplastics (NPs), which can reach aquatic and terrestrial organisms. MPs/NPs in water can access fish's bodies through the gills, triggering an inflammatory response in loco. Furthermore, from the gills, plastic fragments can be transported within the circulatory system altering blood biochemical parameters and hormone levels and leading to compromised immunocompetence and angiogenesis. In addition, it was also possible to observe an unbalanced ROS production, damage in vascular structure, and enhanced thrombosis. MPs/NPs led to cardiotoxicity, pericardial oedema, and impaired heart rate in fish cardiac tissue. MPs/NPs effects on aquatic organisms pose serious health hazards and ecological consequences because they constitute the food chain for humans. Once present in the mammalian body, plastic particles can interact with circulating cells, eliciting an inflammatory response, with genotoxicity and cytotoxicity of immune cells, enhanced haemolysis, and endothelium adhesion. The interaction of MPs/NPs with plasma proteins allows their transport to distant organs, including the heart. As a consequence of plastic fragment internalisation into cardiomyocytes, oxidative stress was increased, and metabolic parameters were altered. In this scenario, myocardial damage, fibrosis and impaired electrophysiological values were observed. In summary, MPs/NPs are an environmental stressor for cardiac function in living organisms, and a risk assessment of their influence on the cardiovascular system certainly merits further analysis.

Nebulization of Model Hydrogel Nanoparticles to Macrophages at the Air-Liquid Interface

Nanoparticle evaluation within the pulmonary airspace has increasingly important implications for human health, with growing interest from drug delivery, environmental, and toxicology fields. While there have been widespread investigations of nanoparticle physiochemical properties following many routes of administration, nanoparticle behavior at the air-liquid interface (ALI) is less well-characterized. In this work, we fabricate two formulations of poly(ethylene)-glycol diacrylate (PEGDA)-based model nanoparticles to establish an in vitro workflow allowing evaluation of nanoparticle charge effects at the ALI. Both cationic and anionic PEGDA formulations were synthesized with similar hydrodynamic diameters around ~225 nm and low polydispersity, with expected surface charges corresponding with the respective functional co-monomer. We find that both formulations are readily nebulized from an aqueous suspension in a commercial Aeroneb® Lab Nebulizer, but the aqueous delivery solution served to slightly increase the overall hydrodynamic and geometric size of the cationic particle formulation. However, nanoparticle loading at 50 μg/ml of either formulation did not influence the resultant aerosol diameter from the nebulizer. To assess aerosol delivery in vitro, we designed a 3D printed adapter capable of ensuring aerosol delivery to transwell 24-well culture plates. Nanoparticle uptake by macrophages was compared between traditional cell culture techniques and that of ALI-cultured macrophages following aerosol delivery. Cell viability was unaffected by nanoparticle delivery using either method. However, only traditional cell culture methods demonstrated significant uptake that was dependent on the nanoparticle surface charge. Concurrently, ALI culture resulted in lower metabolic activity of macrophages than those in traditional cell culture, leading to lower overall nanoparticle uptake at ALI. Overall, this work demonstrates that base-material similarities between both particle formulations provide an expected consistency in aerosol delivery regardless of the nanoparticle surface charge and provides an important workflow that enables a holistic evaluation of aerosolizable nanoparticles.

Investigation of pulmonary toxicity evaluation on mice exposed to polystyrene nanoplastics: The potential protective role of the antioxidant N-acetylcysteine

Accumulating evidences show that the hazardous substance atmospheric nanoplastics increase the respiratory risk of individuals, but the inside toxicity mechanisms to lung tissue remain unclear. This study aims at investigating the potential mechanisms of inhaled cationic polystyrene nanoplastics (amine-polystyrene nanoplastics, APS-NPs)-induced pulmonary toxicity on mice. In vivo, the mice intratracheal administrated with APS-NPs suspension (5 mg/kg) were found inflammatory infiltrates in lung tissues through histopathology analysis. Furthermore, transcriptome analysis demonstrated that 1821 differentially expressed mRNA between APS group and control group were dominantly associated with 288 known KEGG pathways, indicating that APS-NPs might cause early inflammatory responses in lung tissue by activating the NLRP3/capase-1/IL-1β signaling pathway. Moreover, in vitro results also showed that NLRP3 inflammasome could be activated to induce pyroptosis in MLE-12 cells after exposure to APS-NPs. And, MH-S cells after exposure to APS-NPs exhibited increased Irg1 proteins, leading to the increasing generation of ROS and inflammatory factors (e.g., tnf-α, il-6, il-1β). In conclusion, these results revealed that Irg1/NF-κB/NLRP3/Caspase-1 signaling pathway was activated significantly after exposing to APS-NPs, leading to pulmonary toxicity on mice. Intriguingly, prior administration of the clinical antioxidant N-acetylcysteine (NAC) could serve as a possible candidate for the prevention and treatment of pulmonary toxicity induced by APS-NPs. The study contributes to a better understanding of the potential risks of environmental nanoplastics to humans and its improvement measure.

Recent consequences of micro-nanaoplastics (MNPLs) in subcellular/molecular environmental pollution toxicity on human and animals

Microplastics and Nanoplastics (MNPLs) pollution has been recognized as the important environmental pollution caused by human activities in addition to global warming, ozone layer depletion and ocean acidification. Most of the current studies have focused on the toxic effects caused by plastics and have not actively investigated the mechanisms causing cell death, especially at the subcellular level. The main content of this paper focuses on two aspects, one is a review of the current status of MNPLs contamination and recent advances in toxicological studies, which highlights the possible concentration levels of MNPLs in the environment and the internal exposure of humans. It is also proposed to pay attention to the compound toxicity of MNPLs as carriers of other environmental pollutants and pathogenic factors. Secondly, subcellular toxicity is discussed and the modes of entry and intracellular distribution of smaller-size MNPLs are analyzed, with particular emphasis on the importance of organelle damage to elucidate the mechanism of toxicity. Importantly, MNPLs are a new type of environmental pollutant and researchers need to focus not only on their toxicity, but also work with governments to develop measures to reduce plastic emissions, optimize degradation and control plastic aggression against organisms, especially humans, from multiple perspectives.

A review of potential human health impacts of micro- and nanoplastics exposure

This systematic review aims to summarize the current knowledge on biological effects of micro- and nanoplastics (MNPs) on human health based on mammalian systems. An extensive search of the literature led to a total of 133 primary research articles on the health relevance of MNPs. Our findings revealed that although the study of MNP cytotoxicity and inflammatory response represents a major research theme, most studies (105 articles) focused on the effects of polystyrene MNPs due to their wide availability as a well characterised research material that can be manufactured with a large range of particle sizes, fluorescence labelling as well as various surface modifications. Among the 133 studies covered in this review, 117 articles reported adverse health effects after being exposed to MNPs. Mammalian in vitro studies identified multiple biological effects including cytotoxicity, oxidative stress, inflammatory response, genotoxicity, embryotoxicity, hepatotoxicity, neurotoxicity, renal toxicity and even carcinogenicity, while rodent in vivo models confirmed the bioaccumulation of MNPs in the liver, spleen, kidney, brain, lung and gut, presenting adverse effects at different levels including reproductive toxic effects and trans-generational toxicity. In contrast, the remaining 16 studies indicated an insignificant impact of MNPs on humans. A few studies attempted to investigate the mechanisms or factors driving the toxicity of MNPs and identified several determining factors including size, concentration, shape, surface charge, attached pollutants and weathering process, which, however, were not benchmarked or considered by most studies. This review demonstrates that there are still many inconsistencies in the evaluation of the potential health effects of MNPs due to the lack of comparability between studies. Current limitations hindering the attainment of reproducible conclusions as well as recommendations for future research directions are also presented.

Toxicity of micro(nano)plastics with different size and surface charge on human nasal epithelial cells and rats via intranasal exposure

Micro (nano)plastics (MNPs) have become emerging environmental contaminants, yet their toxicity and systemic effects via intranasal exposure remain unclear. This study investigated the in vitro toxicity of thirteen polystyrene MNPs with different surface functionalization (carboxylic (C-PS), amino (A-PS), and bare (PS)) and sizes (20-2000 nm) on human nasal epithelial cells (HNEpCs) at 10-1250 μg/mL as well as their in vivo toxicity to rats via intranasal administration at 125 μg/mL. The in vitro study showed that PS20, PS50, A-PS50, PS500, and A-PS500 significantly inhibited cell viability, which was dependent on particle concentration. A-PS induced higher cytotoxicity than C-PS and PS, and most MNPs inhibited cell proliferation after 24-h. Flow cytometry analysis suggested that PS induced cell apoptosis, while A-PS caused cell necrosis. MNPs were phagocytosed by HNEpCs and entered nucleus. The in vivo study showed that MNPs inhibited dietary behaviors of rats. Histological analysis indicated that PS20, PS200, and A-PS50 thinned out nasal mucosa. Immunohistochemical analysis revealed that exposure to PS20, PS200, and A-PS50 enhanced expression of transient receptor potential cation channel subfamily M (melastatin) member 8 (TRPM8). Systemic effects including hepatocyte cytoplasmic vacuolation and renal tubule dilatation were observed. The results suggested that nasal inhalation of MNPs may disturb energy metabolism and damage upper respiratory tract, liver, and kidneys.

Food and human safety: the impact of microplastics

Plastic waste pollution is one of the biggest problems in the world today. The amount of plastic in the environment continues to increase, and human exposure to microplastic (MP) has become a reality. This subject has attracted the attention of the whole world. The MP problem has also been noticed by the scientific community. The term microplastic is mostly used to define synthetic material with a high polymer content that can have a size range from 0.1 to 5000 µm. This paper aims to characterize the routes of exposure to MP, define its pollution sources, and identify food types contaminated with plastics. This review addresses the current state of knowledge on this type of particles, with particular emphasis on their influence on human health. Adverse effects of MP depend on routes and sources of exposure. The most common route of exposure is believed to be the gastrointestinal tract. Sources of MP include fish, shellfish, water as well as tea, beer, wine, energy drinks, soft drinks, milk, salt, sugar, honey, poultry meat, fruits, and vegetables. Studies have shown that particles of PET, PE, PP, PS, PVC, PA, and PC are the most frequently found in food.

Dietary exposure to polystyrene nanoplastics impairs fasting-induced lipolysis in adipose tissue from high-fat diet fed mice

The health concerns of microplastics (MPs) and nanoplastics (NPs) surge, but the key indicators to evaluate the adverse risks of MPs/NPs are elusive. Recently, MPs/Ps were found to disturb glucose and lipid metabolism in rodents, suggesting that MPs/NPs may play a role in obesity progression. In this study, we firstly demonstrated that the distribution of fluorescent polystyrene nanoplastics (nPS, 60 nm) white adipose tissue (WAT) of mice. Furthermore, nPS could traffic across adipocytes in vitro and reduced lipolysis under β-adrenergic stimulation in adipocytes in vitro and ex vivo. Consistently, chronic oral exposure to nPS at the dietary exposure relevant concentrations (3 and 223 μg/kg body weight) impaired fasting-induced lipid mobilization in obese mice and subsequently contributed to larger adipocyte size in the subcutaneous WAT. In addition, the chronic exposure of nPS induced macrophage infiltration in the small intestine and increased lipid accumulation in the liver, accelerating the disruption of systemic metabolism. Collectively, our findings highlight the potential obesogenic role of nPS via diminishing lipid mobilization in WAT of obese mice and suggest that lipolysis relevant parameters may be used for evaluating the adverse effect of MPs/NPs in clinics.

Polystyrene nanoplastics exacerbate lipopolysaccharide-induced myocardial fibrosis and autophagy in mice via ROS/TGF-β1/Smad

Polystyrene nanoplastics (PS NPs) contamination is a serious problem for human and animal health. Excessive exposure to PS NPs can affect the structure and function of the heart. And lipopolysaccharide (LPS) induces myocardial damage, leading to myocardial fibrosis (MF). To investigate whether PS NPs exacerbate LPS-induced myocardial autophagy and fibrosis, we established in vivo and in vitro models of PS NPs/LPS exposure alone and in combination. We found that PS NPs/LPS exposure disrupts myocardial structure, significantly increases reactive oxygen species (ROS), triggers oxidative stress, promotes TGF-β1/Smad pathway activation, and leads to elevated levels of fibrotic proteins and collagen. Meanwhile, activation of AMPK/mTOR/ULK1 signaling pathway induced autophagy onset, and combined exposure of PS NPs/LPS exacerbated MF and autophagy. H9C2 cells were used for in vitro experiments, and the experimental results showed that the addition of TGF-β receptor inhibitor LY2109761 to the exposed group not only inhibited the upregulation of fibrotic genes but also effectively reduced the expression of autophagic signals, indicating that combined exposure of PS NPs and LPS mediates and regulates cardiac autophagy through TGF-β1. The above results suggest that PS NPs exacerbate LPS-induced MF and autophagy in mice via ROS/TGF-β1/Smad. Our study provides some new evidence to clarify the potential mechanisms of PS NPs-induced cardiotoxicity.