Applications of 3D organoids in toxicological studies: a comprehensive analysis based on bibliometrics and advances in toxicological mechanisms.

A mechanism exploration is an important part of toxicological studies. However, traditional cell and animal models can no longer meet the current needs for in-depth studies of toxicological mechanisms. The three-dimensional (3D) organoid derived from human embryonic stem cells (hESC) or induced pluripotent stem cells (hiPSC) is an ideal experimental model for the study of toxicological effects and mechanisms, which further recapitulates the human tissue microenvironment and provides a reliable method for studying complex cell-cell interactions. This article provides a comprehensive overview of the state of the 3D organoid technology in toxicological studies, including a bibliometric analysis of the existing literature and an exploration of the latest advances in toxicological mechanisms. The use of 3D organoids in toxicology research is growing rapidly, with applications in disease modeling, organ-on-chips, and drug toxicity screening being emphasized, but academic communications among countries/regions, institutions, and research scholars need to be further strengthened. Attempts to study the toxicological mechanisms of exogenous chemicals such as heavy metals, nanoparticles, drugs and organic pollutants are also increasing. It can be expected that 3D organoids can be better applied to the safety evaluation of exogenous chemicals by establishing a standardized methodology.

Low-dose cadmium telluride quantum dots trigger M1 polarization in macrophages through mTOR-mediated transcription factor EB activation.

The increasing application of quantum dots (QDs) increases interactions with organisms. The inflammatory imbalance is a significant manifestation of immunotoxicity. Macrophages maintain inflammatory homeostasis. Using macrophages differentiated by phorbol 12-myristate 13-acetate-induced THP-1 cells as models, the study found that low-dose (5 µM) cadmium telluride QDs (CdTe-QDs) hindered monocyte-macrophage differentiation. CD11b is a surface marker of macrophage, and the addition of CdTe-QDs during induction resulted in a decrease in CD11b expression. Moreover, exposure of differentiated THP-1 macrophage (dTHP-1) to 5 µM CdTe-QDs led to the initiation of M1 polarization. This was indicated by the increased surface marker CD86 expression, along with elevated level of NF-κB and IL-1ß proteins. The potential mechanisms are being explored. The transcription factor EB (TFEB) plays a significant role in immune regulation and serves as a crucial regulator of the autophagic lysosomal pathway. After exposed to CdTe-QDs, TFEB activation-mediated autophagy and M1 polarization were observed to occur simultaneously in dTHP-1. The mTOR signaling pathway contributed to TFEB activation induced by CdTe-QDs. However, mTOR-independent activation of TFEB failed to promote M1 polarization. These results suggest that mTOR-TFEB is an advantageous target to enhance the biocompatibility of CdTe-QDs.

Mitophagy and its regulatory mechanisms in the biological effects of nanomaterials.

Mitophagy is a selective cellular process critical for the removal of damaged mitochondria. It is essential in regulating mitochondrial number, ensuring mitochondrial functionality, and maintaining cellular equilibrium, ultimately influencing cell destiny. Numerous pathologies, such as neurodegenerative diseases, cardiovascular disorders, cancers, and various other conditions, are associated with mitochondrial dysfunctions. Thus, a detailed exploration of the regulatory mechanisms of mitophagy is pivotal for enhancing our understanding and for the discovery of novel preventive and therapeutic options for these diseases. Nanomaterials have become integral in biomedicine and various other sectors, offering advanced solutions for medical uses including biological imaging, drug delivery, and disease diagnostics and therapy. Mitophagy is vital in managing the cellular effects elicited by nanomaterials. This review provides a comprehensive analysis of the molecular mechanisms underpinning mitophagy, underscoring its significant influence on the biological responses of cells to nanomaterials. Nanoparticles can initiate mitophagy via various pathways, among which the PINK1-Parkin pathway is critical for cellular defense against nanomaterial-induced damage by promoting mitophagy. The role of mitophagy in biological effects was induced by nanomaterials, which are associated with alterations in Ca2+ levels, the production of reactive oxygen species, endoplasmic reticulum stress, and lysosomal damage.

Silver nanoparticles induced synaptic degeneration via Ca2+/CaMKII signal and Drp1-dependent mitochondrial disorder in HT22 cells.

Silver nanoparticles (AgNPs) have been widely used in biomedicine and cosmetics, increasing their potential risks in neurotoxicity. But the involved molecular mechanism remains unclear. This study aims to explore molecular events related to AgNPs-induced neuronal damage by RNA-seq, and elucidate the role of Ca2+/CaMKII signal and Drp1-dependent mitochondrial disorder in HT22 cells synaptic degeneration induced by AgNPs. This study found that cell viabilities were decreased by AgNPs in a dose/time-dependent manner. AgNPs also increased protein expression of PINK1, Parkin, synaptophysin, and inhibited PGC-1α, MAP2 and APP protein expression, indicating AgNPs-induced synaptic degeneration involved in disturbance of mitophagy and mitochondrial biogenesis in HT22 cells. Moreover, inhibition of AgNPs-induced Ca2+/CaMKII activation and Drp1/ROS rescued mitophagy disturbance and synaptic degeneration in HT22 cells by reserving aforementioned protein express changes except for PGC-1α and APP protein. Thus, AgNPs-induced synaptic degeneration was mediated by Ca2+/CaMKII signal and Drp1-dependent mitochondrial disorder in HT22 cells, and mitophagy is the sensitive to the mechanism. Our study will provide in-depth molecular mechanism data for neurotoxic evaluation and biomedical application of AgNPs.

Oxidative stress-activated Nrf2 remitted polystyrene nanoplastic-induced mitochondrial damage and inflammatory response in HepG2 cells.

Generated from plastics, microplastics (MPs) and nanoplastics (NPs) are difficult to completely degrade in the natural environment, which can accumulate in almost all lives. Liver is one of the main target organs. In this study, HepG2 and L02 cells were exposed to 0-50 µg/mL polystyrene (PS)-NPs to investigate the mechanism of mitochondrial damage and inflammation. The results showed mitochondria damage and inflammatory caused by NPs, and it can be inhibited by N-acetyl-L-cysteine (NAC). In addition, reactive oxygen species (ROS) activated nuclear factor erythroid-derived factor 2-related factor (Nrf2) pathway. Nrf2 siRNA exacerbated the injury, suggesting Nrf2 plays a protective role. Moreover, p62 siRNA increased ROS and mitochondrial damage by inhibiting Nrf2, but didn't affect the inflammation. In conclusion, Nrf2 was activated by ROS and played a protective role in PS-NPs-mediated hepatotoxicity. This study supplemented the data of liver injury caused by PS-NPs, providing a basis for the safe disposal of plastics.

Comparative oxidative damages induced by silver nanoparticles with different sizes and coatings in Caenorhabditis elegans.

Silver nanoparticles (AgNPs) are widely used in many commercial and medical products. Serious concerns are paid on their adverse potentials to the environment and human health. In this study, toxic effects and oxidative stress induced by AgNPs with different sizes and coatings (20 nm AgNPs, 20 nm polyvinylpyrrolidone (PVP) -AgNPs and 50 nm AgNPs) in Caenorhabditis elegans (C. elegans) were investigated. The toxic effects including the shortened lifespan and decreased frequency of head thrashes and body bends of C. elegans were induced in a dose-dependent manner by AgNPs. The reactive oxygen species (ROS) production and the oxidative stress-related indicators including malondialdehyde (MDA) and glutathione (GSH) in nematodes were changed after exposure to three kinds of AgNPs. These effects were the most obvious in a 20 nm PVP-AgNPs exposure group. AgNPs could also induce the expression of genes related to oxidative stress in nematodes. In addition, the up-regulation of mtl-1 and mtl-2 in nematodes might reduce the oxidative damage caused by AgNPs, by using transgenic strains CF2222 and CL2120 nematodes. Metallothionein (MT), an antioxidant, could relieve the oxidative damage caused by AgNPs. These results suggested that 20 nm PVP-AgNPs with a smaller particle size and better dispersion have stronger toxic effects and the oxidative damage to nematodes. Mtl-1 and mtl-2 might be involved in alleviating the oxidative damage caused by AgNPs. Our findings provide clues for the safety evaluation and mechanism information of metal nanoparticles.

Ag/TiO2 nanohybrids induce fibrosis-related epithelial-mesenchymal transition in lung epithelial cells and the influences of silver content and silver particle size.

The controlled synthesis of silver nanoparticles (AgNPs) decorated TiO2 nanohybrids (Ag/TiO2) for photocatalysis has received considerable attention. These photocatalysts are widely used in environment and energy, resulting in human exposure through inhalation. Pure TiO2 is generally considered a low-toxic nanomaterial. However, little is known about the toxicity after AgNPs loading. In this study, silver-decorated TiO2 nanohybrids were controllably synthesized by the photodeposition method, and their toxic effects on murine lung and human lung epithelial cells were explored. As a result, silver loading significantly enhanced the effect of TiO2 photocatalyst on EMT in lung epithelial cells, potentially acting as a pro-fibrogenic effect in murine lung. Meanwhile, the increase in autophagy vacuoles, LC3-II marker, stub-RFP-sens-GFP-LC3 fluorescence assay, and LC3 turnover assay showed that silver loading also significantly increased autophagy flux. Furthermore, analysis of autophagy inhibition by 3-Methyladenine indicated that the promotion of EMT by silver loading was related to the increased autophagy flux. Intriguingly, the autophagy and EMT biological effects could be alleviated when the silver loading amount was reduced or silver particle size was increased, and the enhanced pro-fibrogenic effect was mitigated at the same time. This study supplemented safety information of Ag-decorated TiO2 nanohybrids and provided methods of controlled synthesis for reducing toxicity.

Artifact Detection and Restoration in Histology Images With Stain-Style and Structural Preservation.

The artifacts in histology images may encumber the accurate interpretation of medical information and cause misdiagnosis. Accordingly, prepending manual quality control of artifacts considerably decreases the degree of automation. To close this gap, we propose a methodical pre-processing framework to detect and restore artifacts, which minimizes their impact on downstream AI diagnostic tasks. First, the artifact recognition network AR-Classifier first differentiates common artifacts from normal tissues, e.g., tissue folds, marking dye, tattoo pigment, spot, and out-of-focus, and also catalogs artifact patches by their restorability. Then, the succeeding artifact restoration network AR-CycleGAN performs de-artifact processing where stain styles and tissue structures can be maximally retained. We construct a benchmark for performance evaluation, curated from both clinically collected WSIs and public datasets of colorectal and breast cancer. The functional structures are compared with state-of-the-art methods, and also comprehensively evaluated by multiple metrics across multiple tasks, including artifact classification, artifact restoration, downstream diagnostic tasks of tumor classification and nuclei segmentation. The proposed system allows full automation of deep learning based histology image analysis without human intervention. Moreover, the structure-independent characteristic enables its processing with various artifact subtypes. The source code and data in this research are available at https://github.com/yunboer/AR-classifier-and-AR-CycleGAN.

ROS-Drp1-mediated mitochondria fission contributes to hippocampal HT22 cell apoptosis induced by silver nanoparticles.

Silver nanoparticles (AgNPs) have widely used in industrial and medical applications for their excellent antibacterial activities. AgNPs can penetrate into the brain and cause neuronal death, but limited evidence focused on toxic effects and mechanic study in hippocampal neuron. This study aimed to investigate the molecular mechanisms of mitochondrial damage and apoptosis in mouse hippocampal HT22 cells and further to explore role of reactive oxygen species (ROS) and GTPase dynamin-related protein 1 (Drp1) in AgNPs-induced neurotoxicity. Our results showed that acute exposure to AgNPs at low doses (2-8 µg/mL) increased ROS generation, decreased mitochondrial membrane potential (MMP) and ATP synthesis in HT22 cells. In addition, AgNPs promoted mitochondrial fragmentation and mitochondria-dependent apoptosis via excessive mitochondrial fission/fusion by 8 µg/mL AgNPs treatment for 24 h. The mechanism was involved in increased protein expression of Drp1, mitochondrial fission protein 1 (Fis1), mitofusin 1/2 (Mfn1/2) and inhibited optic atrophy 1 (OPA1), and mainly mediated by phosphorylation of Drp1 Ser616. The AgNPs-induced mitochondrial impairment and apoptosis was mainly due to their particle-specific effect rather than silver ions release. Furthermore Drp1-mediated mitochondrial fission contributed to mitochondria-dependent apoptosis induced by AgNPs, all aforementioned changes were significantly rescued by N-acetyl-l-cysteine (NAC) and Mdivi-1 except for OPA1 protein expression. Hence, our results provide a novel neurotoxic mechanism to AgNPs-induced neurotoxicity and revealed that the mechanism of mitochondria-dependent apoptosis in HT22 cells was mediated by excessive activation of ROS-Drp1-mitochondrial fission axis. These findings can deepen current evidences on neurotoxicological evaluation of AgNPs and aid in guiding their proper applications in different areas, especially in biomedical use.

ROS and DRP1 interactions accelerate the mitochondrial injury induced by polystyrene nanoplastics in human liver HepG2 cells.

Microplastics have become a serious environmental pollutant and subsequently have harmful effects on human health. Thus, the impacts of microplastics on human cells need to be explored. In the present study, the cytotoxic effects at the subcellular-organelle levels to polystyrene nanoplastics (PS-NPs, diameter 21.5 ± 2.7 nm) were investigated in the human hepatocellular carcinoma (HepG2) cell line. The cell viability exposed to PS-NPs at the concentrations of 6.25, 12.5, 25 and 50 µg/mL for 24 h diminished in a concentration-dependent manner. The PS-NPs treatment induced mitochondrial injuries, including morphological changes, decreased adenosine triphosphate (ATP) production and the loss of mitochondrial membrane potentials (MMP). The PS-NPs treatment could further spark cell apoptosis by upregulating caspase 3, caspase 9, cytochrome c, and Bcl-2 associated X protein (Bax)/B-cell lymphoma-2 (Bcl-2) in HepG2 cells, which is related to the mitochondrial dysfunction. PS-NPs exposure stimulated the excessive cellular reactive oxygen species (ROS) production and also induced mitochondrial fission by upregulating dynamin-related protein 1 (DRP1) and P-DRP1, but downregulating optic atrophy protein 1 (OPA1) and peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1α) expression levels. The above effects on mitochondria damage induced by PS-NPs were reversed by the pretreatment of N-acetylcysteine (NAC), mitochondrial division inhibitor 1 (Mdivi-1) and DRP1 siRNA. The results suggested that the interaction between ROS and DRP1-dependent mitochondrial division could promote mitochondrial lesions and mitochondria-related apoptosis caused by PS-NPs. These findings on molecular mechanisms provide a theoretical basis for preventing the hazards caused by microplastics to human health.

Recombinant human metallothionein-III alleviates oxidative damage induced by copper and cadmium in Caenorhabditis elegans.

Recombinant human metallothionein III (rh-MT-III) is a genetically engineered product produced by Escherichia coli fermentation technology. Its molecules contain abundant reducing sulfhydryl groups, which possess the ability to bind heavy metal ions. The present study was to evaluate the binding effects of rh-MT-III against copper and cadmium in vitro and to investigate the antioxidant activity of rh-MT-III using Caenorhabditis elegans in vivo. For in vitro experiments, the binding rates of copper and cadmium were 91.4% and 97.3% for rh-MT-III at a dosage of 200 µg/mL at 10 h, respectively. For in vivo assays, the oxidative stress induced by copper (CuSO4 , 10 µg/mL) and cadmium (CdCl2 , 10 µg/mL) was significantly reduced after 72 h of exposure to different doses of rh-MT-III (5-500 µg/mL), indicated by restoring locomotion behavior and growth, and reducing malondialdehyde and reactive oxygen species levels in C. elegans. Moreover, rh-MT-III decreased the deposition of lipofuscin and fat content, which could delay the progression of aging. In addition, rh-MT-III (500 µg/mL) promoted the up-regulation of Mtl-1 and Mtl-2 gene expression in C. elegans, which could enhance the resistance to oxidative stress by increasing the enzymatic activity of antioxidant defense system and scavenging free radicals. The results indicated that supplemental rh-MT-III could effectively protect C. elegans from heavy metal stress, providing an experimental basis for the future application and development of rh-MT-III.

Adaptive regulations of Nrf2 alleviates silver nanoparticles-induced oxidative stress-related liver cells injury.

Silver nanoparticles (AgNPs) are widely used in various fields such as industry, agriculture, and medical care because of their excellent broad-spectrum antibacterial activity. However, their extensive use has raised concerns about their health risks. Liver is one of the main target organs for the accumulation and action of AgNPs. Therefore, evaluating the toxic effects of AgNPs on liver cells and its mechanisms of action is crucial for the safe application of AgNPs. In the study, polyvinylpyrrolidone (PVP)-coated AgNPs were characterized. The human hepatoma cell line (HepG2) and the normal hepatic cell line (L02) were exposed to different concentrations of AgNPs (20-160 µg/mL) and pretreated with the addition of N-acetylcysteine (NAC) or by Nrf2 siRNA transfection. NAC was able to inhibit the concentration-dependent increase in the level of apoptosis induced by AgNPs in HepG2 cells and L02 cells. Interestingly, HepG2 cells were more sensitive to AgNPs than L02 cells, and this may be related to the different ROS generation and responses to AgNPs by cancer cells and normal cells. In addition, NAC also alleviated the imbalance of antioxidant system and cell cycle arrest, which may be related to AgNPs-induced DNA damage and autophagy. The knockdown of nuclear factor erythroid-derived factor 2-related factor (Nrf2) found that AgNPs-induced ROS and apoptosis levels were further upregulated, but the cell cycle arrest was alleviated. On the whole, Nrf2 exerts a protective role in AgNPs-induced hepatotoxicity. This study complements the hepatotoxicity mechanisms of AgNPs and provides data for a future exploration of AgNPs-related anti-hepatocellular carcinoma drugs.

Neurodevelopmental toxicity induced by airborne particulate matter.

Airborne particulate matter (PM), the primary component associated with health risks in air pollution, can negatively impact human health. Studies have shown that PM can enter the brain by inhalation, but data on the exact quantity of particles that reach the brain are unknown. Particulate matter exposure can result in neurotoxicity. Exposure to PM poses a greater health risk to infants and children because their nervous systems are not fully developed. This review paper highlights the association between PM and neurodevelopmental toxicity (NDT). Exposure to PM can induce oxidative stress and inflammation, potentially resulting in blood-brain barrier damage and increased susceptibility to development of neurodevelopmental disorders (NDD), such as autism spectrum disorders and attention deficit disorders. In addition, human and animal exposure to PM can induce microglia activation and epigenetic alterations and alter the neurotransmitter levels, which may increase risks for development of NDD. However, the systematic comparisons of the effects of PM on NDD at different ages of exposure are deficient. The elucidation of PM exposure risks and NDT in children during the early developmental stages are of great importance. The synthesis of current research may help to identify markers and mechanisms of PM-induced neurodevelopmental toxicity, allowing for the development of strategies to prevent permanent damage of developing brain.

Silver nanoparticle-induced impaired autophagic flux and lysosomal dysfunction contribute to the microglia inflammation polarization.

Silver nanoparticles (AgNPs) have been incorporated in many consumer and biomedical products. Serious concerns have been expressed about the environmental and public health risks caused by nanoparticles. In previous studies, we found that AgNPs induced microglia polarization of the inflammatory phenotype. Autophagy was a critical for AgNPs-induced neuroinflammation. In the present study, we evaluated in detail the effects of AgNPs in different stages of the autophagy process, and we found that AgNPs induced neuroinflammatory responses and autophagic flux blockage both in the mouse brain and BV2 cells. AgNPs inhibited autophagosome-lysosome fusion and impaired the lysosomal functions by reducing the levels of lysosomal-associated membrane proteins, promoting lysosome membrane permeability and altering the lysosomal acidic microenvironment. These changes resulted in the defects in autophagic substrate clearance and subsequently led neuroinflammation. In addition, the elevation of autophagy could prevent the neuroinflammation induced by AgNPs. As a result, AgNPs hindered autophagic flux by inhibiting autophagosome fusion with lysosomes, thus aggravating the AgNPs-induced neurotoxicity. These findings will provide new insights to investigate the molecular mechanisms of neurotoxicity caused by AgNPs.

Silver nanoparticles induced hippocampal neuronal damage involved in mitophagy, mitochondrial biogenesis and synaptic degeneration.

Silver nanoparticles (AgNPs) could accumulate in the central nervous system (CNS) and induce neurotoxicity for their widespread use in industry and medicine. Mitochondria are vulnerable to toxicity of AgNPs, however, their role in the neurotoxicity remains unclear. This study aimed to evaluate AgNPs-induced synaptic degeneration in mouse hippocampal neurons (at a dose of 12-120 mg/kg BW via intravenous injection), and to further investigate mechanism of mitophagy, mitochondrial biogenesis process in the neurotoxicity. The results indicated that AgNPs accumulated in mouse hippocampal neurons and induced neurological deficits of learning and memory, which involved in synaptic degeneration accompanied with mitochondrial damage. Mechanistically, AgNPs exposure increased protein expression of PTEN-induced kinase 1 (PINK1), Parkin and inhibited peroxisome proliferator-activated receptor coactivator 1 alpha (PGC-1α) protein expression, caused disturbed mitophagy and mitochondrial biogenesis. AgNPs also induced synaptic damage by increasing the protein expression of synaptophysin and decreasing PSD95, MAP2 protein expression. AgNPs exposure even promoted protein expression of amyloid precursor protein (APP) using in amyloid-ß (Aß) cleavage. Furthermore, AgNPs induced hippocampal neuronal synaptic degeneration, mitophagy and mitochondrial biogenesis is dependent on particle-specific AgNPs rather than released silver ions. Our research could provide insights into the regulatory mechanisms of AgNPs-induced neurotoxicity. This study will shed the light of neurotoxicological evaluation of nanoparticles and possible early warning of biomedical applications.

Protein corona mitigated the cytotoxicity of CdTe QDs to macrophages by targeting mitochondria.

Despite the potential of cadmium telluride quantum dots (CdTe QDs) in bioimaging and drug delivery, their toxic effects have been documented. It is known that the immunotoxicity of CdTe QDs targeting macrophages is one of their adverse effects, and the protein corona (PC) will affect the biological effects of QDs. In order to prove whether the PC-CdTe QDs complexes could alleviate the toxicity of CdTe QDs without weakening their luminescence, we investigated the impact of protein corona formed in fetal bovine serum (FBS) on the cytotoxicity of CdTe QDs to mitochondria. RAW264.7 cells were used as the model to compare the effects of CdTe QDs and PC-CdTe QDs complexes on the structure, function, quantity, morphology, and mitochondrial quality control of mitochondria. As result, the protein corona form in FBS alleviated the inhibition of CdTe QDs on mitochondrial activity, the damage to mitochondrial membrane, the increase of ROS, and the reduction of ATP content. Also, CdTe QDs increased the number of mitochondria in macrophages, while the complexes did not. In line with this, the morphology of mitochondrial network in macrophages which were exposed to CdTe QDs and PC-CdTe QDs complexes was different. CdTe QDs transformed the network into fragments, punctuations, and short rods, while PC-CdTe QDs complexes made the mitochondrial network highly branched, which was related to the imbalance of mitochondrial fission and fusion. Mechanically, CdTe QDs facilitated mitochondrial fission and inhibited mitochondrial fusion, while protein corona reversed the phenomenon caused by QDs. Besides mitochondrial dynamics, mitochondrial biogenesis and mitophagy were also affected. CdTe QDs increased the expression of mitochondrial biogenesis signaling molecules including PGC-1α, NRF-1 and TFAM, while PC-CdTe QDs complexes played the opposite role. With regard to mitophagy, they both showed promoting effect. In conclusion, the formation of protein corona alleviated the toxic effects of CdTe QDs on the mitochondria in macrophages and affected mitochondrial quality control. Under the premise of ensuring the fluorescence properties of CdTe QDs, these findings provided useful insight into reducing the toxicity of CdTe QDs from two perspectives: protein corona and mitochondria, and shared valuable information for the safe use of QDs.

Urban fine particulate matter causes cardiac hypertrophy through calcium-mediated mitochondrial bioenergetics dysfunction in mice hearts and human cardiomyocytes.

In recent years, the cardiovascular toxicity of urban fine particulate matter (PM2.5) has sparked significant alarm. Mitochondria produce 90% of ATP and make up 30% of the volume of cardiomyocytes. Thus knowledge of myocardial mitochondrial dysfunction due to PM2.5 exposure is essential for further cardiotoxic effects. Here, the mechanism of PM2.5-induced cardiac hypertrophy through calcium overload and mitochondrial dysfunction was investigated in vivo and in vitro. Male and female BALB/c mice were given 1.28, 5.5, and 11 mg PM2.5/kg bodyweight weekly through oropharyngeal inhalation for four weeks and were assigned to low, medium, and high dose groups, respectively. PM2.5-induced myocardial edema and cardiac hypertrophy were detected in the high-dose group. Mitochondria were scattered and ruptured with abnormal ultrastructural morphology. In vitro experiments on human cardiomyocyte AC16 showed that exposure to PM2.5 for 24 h caused opened mitochondrial permeability transition pore --leading to excessive calcium production, decreased mitochondrial membrane potential, weakened mitochondrial respiratory metabolism capacity, and decreased ATP production. Nevertheless, the administration of calcium chelator ameliorated the mitochondrial damage in the PM2.5-treated group. Our in vivo and in vitro results confirmed that calcium overload under PM2.5 exposure triggered mTOR/AKT/GSK-3ß activation, leading to mitochondrial bioenergetics dysfunction and cardiac hypertrophy.

NADPH oxidases regulate endothelial inflammatory injury induced by PM2.5 via AKT/eNOS/NO axis.

Fine particulate matter (PM2.5 )-induced detrimental cardiovascular effects have been widely concerned, especially for endothelial cells, which is the first barrier of the cardiovascular system. Among potential mechanisms involved, reactive oxidative species take up a crucial part. However, source of oxidative stress and its relationship with inflammatory response have been rarely studied in PM2.5 -induced endothelial injury. Here, as a key oxidase that catalyzes redox reactions, NADPH oxidase (NOX) was investigated. Human umbilical vein endothelial cells (EA.hy926) were exposed to Standard Reference Material 1648a of urban PM2.5 for 24 h, which resulted in NOX-sourced oxidative stress, endothelial dysfunction, and inflammation induction. These are manifested by the up-regulation of NOX, increase of superoxide anion and hydrogen peroxide, elevated endothelin-1 (ET-1) and asymmetric dimethylarginine (ADMA) level, reduced nitric oxide (NO) production, and down-regulation of phosphorylation of endothelial NO synthase (eNOS) with increased levels of inducible NO synthase, as well as the imbalance between tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1), and changes in the levels of pro-inflammatory and anti-inflammatory factors. However, administration of NOX1/4 inhibitor GKT137831 alleviated PM2.5 -induced elevated endothelial dysfunction biomarkers (NO, ET-1, ADMA, iNOS, and tPA/PAI-1), inflammatory factors (IL-1ß, IL-10, and IL-18), and adhesion molecules (ICAM-1, VCAM-1, and P-selectin) and also passivated NOX-dependent AKT and eNOS phosphorylation that involved in endothelial activation. In summary, PM2.5 -induced NOX up-regulation is the source of ROS in EA.hy926, which activated AKT/eNOS/NO signal response leading to endothelial dysfunction and inflammatory damage in EA.hy926 cells.

The crosstalk between DRP1-dependent mitochondrial fission and oxidative stress triggers hepatocyte apoptosis induced by silver nanoparticles.

Previous studies have revealed that the liver is the main target organ of deposition for engineered nanoparticles. The hepatotoxicity of silver nanoparticles (AgNPs), the widely used antimicrobial nanoparticles, has been of great interest. However, little is known about the regulatory mechanism of the mitochondria in AgNP-induced hepatotoxicity. In the present study, we found that AgNPs, rather than silver ions, induced mitochondrial dynamics disorders, oxidative stress, and mitochondria-dependent hepatocyte apoptosis in mice. Using human hepatocellular carcinoma (HepG2) cells, we confirmed that the interaction between dynamin-related protein 1 (DRP1)-dependent mitochondrial fission and oxidative stress promoted mitochondrial damage and mitochondria-dependent apoptosis induced by AgNPs, as determined by the elimination of DRP1 or addition of N-acetylcysteine (NAC). Interestingly, the crosstalk between DRP1-dependent mitochondrial fission and oxidative stress also activated mitophagy and autophagy flux blocking. Phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) gene silencing contributed to the aggravation of mitochondrial damage, oxidative stress, and apoptosis. These results revealed that the interplay between mitochondrial fission and oxidative stress induced mitophagy defects and triggered AgNP-induced mitochondria-dependent apoptosis in liver cells both in vivo and in vitro. Our findings provide a perspective for the mechanism of hepatotoxicity induced by exposure to metal NPs.