Zinc Oxide Nanoparticles Induce Ferroptotic Neuronal Cell Death in vitro and in vivo

Integrated transcriptome and metabolomic analyses uncover the mechanism of cadmium-caused mouse spermatogonia apoptosis via inducing endoplasmic reticulum stress

Cadmium (Cd) is a well-recognized male reproductive toxicant that can cause testicular germ cell apoptosis. However, the underlying mechanism needs investigation. CG-1 mouse spermatogonia (spg) cells were treated with 20μM cadmium chloride (CdCl2) for 24h. Cell apoptosis was measured, and the expressions of key genes and protein biomarkers involved in endoplasmic reticulum (ER) stress were detected, respectively. Untargeted metabolomics was performed to identify different metabolites, and transcriptome analysis was conducted to screen differentially expressed genes (DEGs). Our results indicated that CdCl2 exposure caused cell apoptosis, and DEGs were involved in several apoptosis-related pathways. Moreover, CdCl2 exposure apparently increased the mRNA and protein expressions levels of both GRP78 and ATF6α, disrupting the expression of various metabolites, particularly amino acids. Conclusively, our study reveals the pathway of CdCl2 toxicity on mouse spg, providing a deep understanding of CdCl2-induced testicular toxicity.

Ferroptosis implication in environmental-induced neurotoxicity

Neurotoxicity, stemming from exposure to various chemical, biological, and physical agents, poses a substantial threat to the intricate network of the human nervous system. This article explores the implications of ferroptosis, a regulated form of programmed cell death characterized by iron-dependent lipid peroxidation, in environmental-induced neurotoxicity. While apoptosis has historically been recognized as a primary mechanism in neurotoxic events, recent evidence suggests the involvement of additional pathways, including ferroptosis. The study aims to conduct a comprehensive review of the existing literature on ferroptosis induced by environmental neurotoxicity across diverse agents such as natural toxins, insecticides, particulate matter, acrylamide, nanoparticles, plastic materials, metal overload, viral infections, anesthetics, chemotherapy, and radiation. The primary objective is to elucidate the diverse mechanisms through which these agents trigger ferroptosis, leading to neuronal cell death. Furthermore, the article explores potential preventive or therapeutic strategies that could mitigate ferroptosis, offering insights into protective measures against neurological damage induced by environmental stressors. This comprehensive review contributes to our evolving understanding of neurotoxicological processes, highlighting ferroptosis as a significant contributor to neuronal cell demise induced by environmental exposures. The insights gained from this study may pave the way for the development of targeted interventions to protect against ferroptosis-mediated neurotoxicity and ultimately safeguard public health.

Zinc oxide nanoparticles induces cell death and consequently leading to incomplete neural tube closure through oxidative stress during embryogenesis

The implementation of Zinc oxide nanoparticles (ZnO NPs) raises concerns regarding their potential toxic effects on human health. Although more and more researches have confirmed the toxic effects of ZnO NPs, limited attention has been given to their impact on the early embryonic nervous system. This study aimed to explore the impact of exposure to ZnO NPs on early neurogenesis and explore its underlying mechanisms. We conducted experiments here to confirm the hypothesis that exposure to ZnO NPs causes neural tube defects in early embryonic development. We first used mouse and chicken embryos to confirm that ZnO NPs and the Zn2+ they release are able to penetrate the placental barrier, influence fetal growth and result in incomplete neural tube closure. Using SH-SY5Y cells, we determined that ZnO NPs-induced incomplete neural tube closure was caused by activation of various cell death modes, including ferroptosis, apoptosis and autophagy. Moreover, dissolved Zn2+ played a role in triggering widespread cell death. ZnO NPs were accumulated within mitochondria after entering cells, damaging mitochondrial function and resulting in the over production of reactive oxygen species, ultimately inducing cellular oxidative stress. The N-acetylcysteine (NAC) exhibits significant efficacy in mitigating cellular oxidative stress, thereby alleviating the cytotoxicity and neurotoxicity brought about by ZnO NPs. These findings indicated that the exposure of ZnO NPs in early embryonic development can induce cell death through oxidative stress, resulting in a reduced number of cells involved in early neural tube closure and ultimately resulting in incomplete neural tube closure during embryo development. The findings of this study could raise public awareness regarding the potential risks associated with the exposure and use of ZnO NPs in early pregnancy.

Nanoparticles and neurodegeneration: Insights on multiple pathways of programmed cell death regulated by nanoparticles

Currently, nanoparticles (NPs) are extensively applied in the diagnosis and treatment of neurodegenerative diseases (NDs). With the rapid development and increasing exposure to the public, the potential neurotoxicity associated with NDs caused by NPs has attracted the researchers' attentions but their biosafety assessments are still far behind relevant application studies. Based on recent research, this review aims to conduct a comprehensive and systematic analysis of neurotoxicity induced by NPs. The 191 studies selected according to inclusion and exclusion criteria were imported into the software, and the co-citations and keywords of the included literatures were analyzed to find the breakthrough point of previous studies. According to the available studies, the routes of NPs entering into the normal and injured brain were various, and then to be distributed and accumulated in living bodies. When analyzing the adverse effects induced by NPs, we focused on multiple programmed cell deaths (PCDs), especially ferroptosis triggered by NPs and their tight connection and crosstalk that have been found playing critical roles in the pathogenesis of NDs and their underlying toxic mechanisms. The activation of multiple PCD pathways by NPs provides a scientific basis for the occurrence and development of NDs. Furthermore, the adoption of new methodologies for evaluating the biosafety of NPs would benefit the next generation risk assessment (NGRA) of NPs and their toxic interventions. This would help ensure their safe application and sustainable development in the field of medical neurobiology.

Targeting ferroptosis and ferritinophagy: new targets for cardiovascular diseases

Cardiovascular diseases (CVDs) are a leading factor driving mortality worldwide. Iron, an essential trace mineral, is important in numerous biological processes, and its role in CVDs has raised broad discussion for decades. Iron-mediated cell death, namely ferroptosis, has attracted much attention due to its critical role in cardiomyocyte damage and CVDs. Furthermore, ferritinophagy is the upstream mechanism that induces ferroptosis, and is closely related to CVDs. This review aims to delineate the processes and mechanisms of ferroptosis and ferritinophagy, and the regulatory pathways and molecular targets involved in ferritinophagy, and to determine their roles in CVDs. Furthermore, we discuss the possibility of targeting ferritinophagy-induced ferroptosis modulators for treating CVDs. Collectively, this review offers some new insights into the pathology of CVDs and identifies possible therapeutic targets.

Zinc oxide nanoparticles have biphasic roles on Mycobacterium-induced inflammation by activating autophagy and ferroptosis mechanisms in infected macrophages

The ability of zinc oxide nanoparticles (ZnONPs) to induce bacteriostasis in Mycobacterium tuberculosis (M. tb) and their roles in regulating the pathogenic activities of immune cells have been reported previously, but the specific mechanisms underlying these regulatory functions remain unclear. This work aimed to determine how ZnONPs play the antibacterial role against M. tb. In vitro activity assays were employed to determine the minimum inhibitory concentrations (MICs) of the ZnONPs against various strains of M. tb (BCG, H37Rv, and clinical susceptible MDR and XDR strains). The ZnONPs had MICs of 0.5-2 mg/L against all tested isolates. In addition, changes in the expression levels of autophagy and ferroptosis-related markers in BCG-infected macrophages exposed to ZnONPs were measured. BCG-infected mice that were administered ZnONPs were used to determine the ZnONPs functions in vivo. ZnONPs decreased the number of bacteria engulfed by the macrophages in a dose-dependent manner, while different doses of ZnONPs also affected inflammation in different directions. Although ZnONPs enhanced the BCG-induced autophagy of macrophages in a dose-dependent manner, only low doses of ZnONPs activated autophagy mechanisms by increasing the levels of pro-inflammatory factors. The ZnONPs also enhanced BCG-induced ferroptosis of macrophages at high doses. Co-administration of a ferroptosis inhibitor with the ZnONPs improved the anti-Mycobacterium activity of ZnONPs in an in vivo mouse model and alleviated acute lung injury caused by ZnONPs. Based on the above findings, we conclude that ZnONPs may act as potential antibacterial agents in future animal and clinical studies.

Assessing regulated cell death modalities as an efficient tool for in vitro nanotoxicity screening: a review

Nanomedicine is a fast-growing field of nanotechnology. One of the major obstacles for a wider use of nanomaterials for medical application is the lack of standardized toxicity screening protocols for assessing the safety of newly synthesized nanomaterials. In this review, we focus on less frequently studied nanomaterials-induced regulated cell death (RCD) modalities, including eryptosis, necroptosis, pyroptosis, and ferroptosis, as a tool for in vitro nanomaterials safety evaluation. We summarize the latest insights into the mechanisms that mediate these RCDs in response to nanomaterials exposure. Comprehensive data from reviewed studies suggest that ROS (reactive oxygen species) overproduction and ROS-mediated pathways play a central role in nanomaterials-induced RCDs activation. On the other hand, studies also suggest that individual properties of nanomaterials, including size, shape, or surface charge, could determine specific toxicity pathways with consequent RCD induction as well. We anticipate that the evaluation of RCDs can become one of the mechanism-based screening methods in nanotoxicology. In addition to the toxicity assessment, evaluation of necroptosis-, pyroptosis-, and ferroptosis-promoting capacity of nanomaterials could simultaneously provide useful information for specific medical applications as could be their anti-tumor potential. Moreover, a detailed understanding of molecular mechanisms driving nanomaterials-mediated induction of immunogenic RCDs will substantially aid novel anti-tumor nanodrugs development.

A nitric-oxide driven chemotactic nanomotor for enhanced immunotherapy of glioblastoma

The major challenges of immunotherapy for glioblastoma are that drugs cannot target tumor sites accurately and properly activate complex immune responses. Herein, we design and prepare a kind of chemotactic nanomotor loaded with brain endothelial cell targeting agent angiopep-2 and anti-tumor drug (Lonidamine modified with mitochondrial targeting agent triphenylphosphine, TLND). Reactive oxygen species and inducible nitric oxide synthase (ROS/iNOS), which are specifically highly expressed in glioblastoma microenvironment, are used as chemoattractants to induce the chemotactic behavior of the nanomotors. We propose a precise targeting strategy of brain endothelial cells-tumor cells-mitochondria. Results verified that the released NO and TLND can regulate the immune circulation through multiple steps to enhance the effect of immunotherapy, including triggering the immunogenic cell death of tumor, inducing dendritic cells to mature, promoting cytotoxic T cells infiltration, and regulating tumor microenvironment. Moreover, this treatment strategy can form an effective immune memory effect to prevent tumor metastasis and recurrence.

Ferroptosis contributes to nickel-induced developmental neurotoxicity in zebrafish

Nickel (Ni) is a widely utilized heavy metal that can cause environmental pollution and health hazards. Its safety has attracted the attention of both the environmental ecology and public health fields. While the central nervous system (CNS) is one of the main targets of Ni, its neurotoxicity and the underlying mechanisms remain unclear. Here, by taking advantage of the zebrafish model for live imaging, genetic analysis and neurobehavioral studies, we reveal that the neurotoxic effects induced by exposure to environmentally relevant levels of Ni are closely related to ferroptosis, a newly-described form of iron-mediated cell death. In vivo two-photon imaging, neurobehavioral analysis and transcriptome sequencing consistently demonstrate that early neurodevelopment, neuroimmune function and vasculogenesis in zebrafish larvae are significantly affected by environmental Ni exposure. Importantly, exposure to various concentrations of Ni activates the ferroptosis pathway, as demonstrated by physiological/biochemical tests, as well as the expression of ferroptosis markers. Furthermore, pharmacological intervention of ferroptosis via deferoxamine (DFO), a classical iron chelating agent, strongly implicates iron dyshomeostasis and ferroptosis in these Ni-induced neurotoxic effects. Thus, this study elucidates the cellular and molecular mechanisms underlying Ni neurotoxicity, with implications for our understanding of the physiologically damaging effects of other environmental heavy metal pollutants.

Disruption of the lung-gut-brain axis is responsible for cortex damage induced by pulmonary exposure to zinc oxide nanoparticles

Increasing evidence shows that gut microbiota is important for host health in response to metal nanomaterials exposure. However, the effect of gut microbiota on the cortex damage caused by pulmonary exposure to zinc oxide nanoparticles (ZnONPs) remains mainly unknown. In this study, a total of 48 adult C57BL/6J mice were intratracheally instilled with 0.6 mg/kg ZnONPs in the presence or absence of antibiotics (ABX) treatment. Besides, 24 mice were treated with or without fecal microbiota transplantation (FMT) after the intraperitoneal administration of ABX. Our results demonstrated for the first time that dysbiosis induced by ABX treatment significantly aggravated cortex damage induced by pulmonary exposure to ZnONPs. Such damage might highly occur through the induction of oxidative stress, manifested by the enhancement of antioxidative enzymes and products of lipid peroxidation. However, ferroptosis was not involved in this process. Interestingly, our data revealed that ABX treatment exacerbated the alterations of gut-brain peptides (including Sst, Sstr2, and Htr4) induced by ZnONPs in both gut and cortex tissues. Moreover, fecal microbiota transplantation (FMT) was able to alleviate cerebral cortex damage, oxidative stress, and alterations of gut-brain peptides induced by pulmonary exposure to ZnONPs. The results together indicate that pulmonary exposure to ZnONPs causes cerebral cortex damage possibly via the disruption of the lung-gut-brain axis. These findings not only propose valuable insights into the mechanism of ZnONPs neurotoxicity but also provide a potential therapeutic method against brain disorders induced by pulmonary exposure to ZnONPs. AVAILABILITY OF DATA AND MATERIALS: The datasets used and/or analyzed during the current study are available from the The corresponding author on reasonable request.

Exploring the Physicochemical, Electroactive, and Biodelivery Properties of Metal Nanoparticles on Peripheral Nerve Regeneration

Despite the advances in the regeneration/rehabilitation field of damaged tissues, the functional recovery of peripheral nerves (PNs), especially in a long gap injury, is considered a great medical challenge. Recent progress in nanomedicine has provided great hope for PN regeneration through the strategy of controlling cell behavior by metal nanoparticles individually or loaded on scaffolds/conduits. Despite the confirmed toxicity of metal nanoparticles due to long-term accumulation in nontarget tissues, they play a role in the damaged PN regeneration based on the topography modification of scaffolds/conduits, enhancing neurotrophic factor secretion, the ion flow improvement, and the regulation of electrical signals. Determining the fate of neural progenitor cells would be a major achievement in PN regeneration, which seems to be achievable by metal nanoparticles through altering cell vital approaches and controlling their functions. Therefore, in this literature, an attempt was made to provide an overview of the effective activities of metal nanoparticles on the PN regeneration, until the vital clues of the PN regeneration and how they are changed by metal nanoparticles are revealed to the researcher.

DBDPE and ZnO NPs synergistically induce neurotoxicity of SK-N-SH cells and activate mitochondrial apoptosis signaling pathway and Nrf2-mediated antioxidant pathway

Decabromodiphenyl ethane (DBDPE), a new brominated flame retardant, could negatively affect neurobehavior and pose health risks to humans. Humans are also exposed to widely used nanomaterials. This study investigated the combined toxic effects and action types of DBDPE and Zinc oxide nanoparticles (ZnO NPs) on human neuroblastoma SK-N-SH cells and the toxicity mechanisms. DBDPE inhibited the viability of SK-N-SH cells by 21.87% at 25 mg/L. ZnO NPs synergistically exacerbated the toxic effects of DBDPE. DBDPE and ZnO NPs caused excessive ROS production and inhibition of antioxidant enzyme (SOD and GSH) activity in cells, thus causing oxidative cellular damage. Moreover, DBDPE and ZnO NPs caused apoptosis by disrupting mitochondrial kinetic homeostasis, reducing mitochondrial membrane potential (MMP), increasing cytochrome C release and regulating Bax/Bcl-2 and Caspase-3 mRNA and protein expression. DBDPE and ZnO NPs increased the mRNA expression of nuclear factor erythroid 2- related factor (Nrf2) and its downstream genes. The molecular mechanisms revealed that oxidative stress, apoptosis and mitochondrial dysfunction were the critical factors in combined cytotoxicity. The bioinformatics analysis further indicated that co-exposure affected Nrf2 activation, apoptotic factors expression and mitochondrial fusion. The findings enrich the risk perception of neurotoxicity caused by DBDPE and ZnO NPs.

Naringenin attenuates inflammation, apoptosis, and ferroptosis in silver nanoparticle-induced lung injury through a mechanism associated with Nrf2/HO-1 axis: In vitro and in vivo studies

With the wide application of silver nanoparticles (AgNPs), their potential damage to human health needs to be investigated. Lung is one of the main target organs after inhalation of AgNPs. Naringenin has been reported to have anti-inflammatory and anti-oxidative properties. This study aims to evaluate the protective effects of naringenin against AgNPs-induced lung injury and determine the underlying mechanism. In in vivo experiments, AgNPs were intratracheally instilled into ICR mice (l mg/kg) to establish a lung injury model. These mice were then treated with naringenin by oral gavage (25, 50, 100 mg/kg) for three days. Naringenin treatment decreased the levels of white blood cells, neutrophils, and lymphocytes in the blood, ameliorated lung injury, suppressed the release of pro-inflammatory cytokines, normalized ferroptotic markers and prevented oxidative stress with elevating Nrf2 and HO-1 protein expressions in lung. In in vitro experiments, BEAS-2B cells were firstly treated with AgNPs (320 μg/mL) and then naringenin (25, 50, and 100 μM), respectively. Naringenin attenuated AgNPs-induced oxidative stress and inflammatory response. Moreover, naringenin attenuated AgNPs-induced apoptosis with modulated low BAX, CytC, cleaved Caspase9, cleaved Caspase3 but high Bcl2. Furthermore, naringenin effectively decreased ferroptotic markers and increased the protein expressions of Nrf2 and HO-1, as well as increased the nuclear translocation of Nrf2. Importantly, the anti-apoptotic and anti-ferroptotic effects of naringenin in BEAS-2B cells were found to be at least partially Nrf2-dependent. These results indicated that naringenin exerted anti-inflammation, anti-apoptosis, and anti-ferroptosis effects and protected against AgNPs-induced lung injury at least partly via activating Nrf2/HO-1 signaling pathway.

The emerging roles of ferroptosis in cells of the central nervous system

Ferroptosis is morphologically characterized by shrunken mitochondria and biochemically characterized by iron overload, lipid peroxidation and lipid reactive oxygen species (ROS) accumulation; these phenomena are suppressed by iron chelation, genetic inhibition of cellular iron uptake, and intervention on other pathways such as lipid metabolism. The induction of ferroptosis may be related to pathological cellular conditions in the central nervous system (CNS); thus, ferroptosis may cause disability via CNS damage. Here, we review the role of ferroptosis in the main cells of the CNS, including glial cells, neurons, and pericytes; in various diseases of the CNS; and in the interaction of glia and neurons in CNS diseases. Some small molecules and traditional Chinese drugs which inhibit ferroptosis in cells of the CNS are shown as potential therapeutic strategies for neurological diseases.

Recombinant ACE2 protein protects against acute lung injury induced by SARS-CoV-2 spike RBD protein

Background

SARS-CoV-2 infection leads to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Both clinical data and animal experiments suggest that the renin–angiotensin system (RAS) is involved in the pathogenesis of SARS-CoV-2-induced ALI. Angiotensin-converting enzyme 2 (ACE2) is the functional receptor for SARS-CoV-2 and a crucial negative regulator of RAS. Recombinant ACE2 protein (rACE2) has been demonstrated to play protective role against SARS-CoV and avian influenza-induced ALI, and more relevant, rACE2 inhibits SARS-CoV-2 proliferation in vitro. However, whether rACE2 protects against SARS-CoV-2-induced ALI in animal models and the underlying mechanisms have yet to be elucidated.

Methods and Results

Here, we demonstrated that the SARS-CoV-2 spike receptor-binding domain (RBD) protein aggravated lipopolysaccharide (LPS)-induced ALI in mice. SARS-CoV-2 spike RBD protein directly binds and downregulated ACE2, leading to an elevation in angiotensin (Ang) II. AngII further increased the NOX1/2 through AT1R, subsequently causing oxidative stress and uncontrolled inflammation and eventually resulting in ALI/ARDS. Importantly, rACE2 remarkably reversed SARS-CoV-2 spike RBD protein-induced ALI by directly binding SARS-CoV-2 spike RBD protein, cleaving AngI or cleaving AngII.

Conclusion

This study is the first to prove that rACE2 plays a protective role against SARS-CoV-2 spike RBD protein-aggravated LPS-induced ALI in an animal model and illustrate the mechanism by which the ACE2-AngII-AT1R-NOX1/2 axis might contribute to SARS-CoV-2-induced ALI.

Crosstalk between regulated necrosis and micronutrition, bridged by reactive oxygen species

The discovery of regulated necrosis revitalizes the understanding of necrosis from a passive and accidental cell death to a highly coordinated and genetically regulated cell death routine. Since the emergence of RIPK1 (receptor-interacting protein kinase 1)-RIPK3-MLKL (mixed lineage kinase domain-like) axis-mediated necroptosis, various other forms of regulated necrosis, including ferroptosis and pyroptosis, have been described, which enrich the understanding of pathophysiological nature of diseases and provide novel therapeutics. Micronutrients, vitamins, and minerals, position centrally in metabolism, which are required to maintain cellular homeostasis and functions. A steady supply of micronutrients benefits health, whereas either deficiency or excessive amounts of micronutrients are considered harmful and clinically associated with certain diseases, such as cardiovascular disease and neurodegenerative disease. Recent advance reveals that micronutrients are actively involved in the signaling pathways of regulated necrosis. For example, iron-mediated oxidative stress leads to lipid peroxidation, which triggers ferroptotic cell death in cancer cells. In this review, we illustrate the crosstalk between micronutrients and regulated necrosis, and unravel the important roles of micronutrients in the process of regulated necrosis. Meanwhile, we analyze the perspective mechanism of each micronutrient in regulated necrosis, with a particular focus on reactive oxygen species (ROS).

PM2 .5 exposure-induced ferroptosis in neuronal cells via inhibiting ERK/CREB pathway

PM_2.5 exposure has been demonstrated to correlate with neurological disorders recently. Ferroptosis is recognized as a newly found programmed form of cell death associated with neurodegenerative diseases, while glutathione peroxidase 4 (GPX4) is a key regulator of ferroptosis. However, the relationship between PM_2.5 -induced neurotoxicity and ferroptosis is still unclear. The current study aims to investigate if ferroptosis is involved in neurotoxicity post PM_2.5 exposure and its underlying mechanism. The PM_2.5 -treated neuronal Neuro-2a (N2A) and SH-SY5Y cells were applied to the current study. The results showed that PM_2.5 significantly increased the neuronal cell death, yet the ferroptosis antagonist Ferrostain-1 (Fer-1) markedly decreased the cell death induced by PM_2.5 . Western blot further confirmed that ferroptosis was triggered post PM_2.5 treatment in N2A cells by decreasing expressions of GPX4 and ferritin heavy chain (FTH), as well as enhancing expressions of ferritin light chain (FTL) and transferrin receptor protein (TFRC). Meanwhile, PM_2.5 treatment augmented neuronal oxidative damage and mitochondrial dysfunction. The bioinformatic analysis indicated that CREB could be the regulator of GPX4, and our results showed that ERK/CREB pathway was down-regulated in N2A cells post PM_2.5 treatment. The addition of ERK1/2 agonist post PM_2.5 treatment significantly inhibit ferroptosis via increasing the expression of GPX4. Taken together, the present study demonstrated that PM_2.5 -induced ferroptosis via inhibiting ERK/CREB pathway, and these findings will advance our knowledge of PM_2.5 -induced cytotoxicity in the nervous system.

The role of ferroptosis mediated by NRF2/ERK-regulated ferritinophagy in CdTe QDs-induced inflammation in macrophage

Cadmium telluride quantum dots (CdTe QDs) exist in the environment due to the abandonment of products. There is a potential risk to organisms and toxic mechanism is worth exploring. In this study, 12.5 μmol/Kg body weight CdTe QDs triggered systemic and local inflammatory response in mice and activated macrophages, then the mechanism of activating macrophages to overexpress IL-1β and IL-6 was explored. RAW264.7 macrophages were used, and after macrophages exposing to 1 μM CdTe QDs for 24 h, oxidative stress occurred. Further investigation found that CdTe QDs triggered ferroptosis in RAW264.7 cells. And deferoxamine mesylate alleviated the excessive lipid hydroperoxide caused by QDs. Mechanistically, CdTe QDs-provoked decrease of nuclear factor erythroid 2-related factor 2 (NRF2) elicited phosphorylation of extracellular regulated protein kinases1/2 (ERK1/2) and then activated ferritinophagy, which made ferritin heavy chain 1 (FTH1) degraded in lysosome and proteasome to release free iron ions to initiate ferroptosis in macrophages. This paper updates the mechanism of macrophage activation by CdTe QDs with regard to ferritinophagy, and more importantly, identifies the key role of NRF2 and ERK1/2. Our research extends the role of ferroptosis in inflammatory responses triggered by nanoparticles (NPs) in macrophages and provides insightful reference for toxicity assessment of NPs.

Ferroptosis as a mechanism of non-ferrous metal toxicity

Ferroptosis is a recently discovered form of regulated cell death, implicated in multiple pathologies. Given that the toxicity elicited by some metals is linked to alterations in iron metabolism and induction of oxidative stress and lipid peroxidation, ferroptosis might be involved in such toxicity. Although direct evidence is insufficient, certain pioneering studies have demonstrated a crosstalk between metal toxicity and ferroptosis. Specifically, the mechanisms underlying metal-induced ferroptosis include induction of ferritinophagy, increased DMT-1 and TfR cellular iron uptake, mitochondrial dysfunction and mitochondrial reactive oxygen species (mitoROS) generation, inhibition of Xc-system and glutathione peroxidase 4 (GPX4) activity, altogether resulting in oxidative stress and lipid peroxidation. In addition, there is direct evidence of the role of ferroptosis in the toxicity of arsenic, cadmium, zinc, manganese, copper, and aluminum exposure. In contrast, findings on the impact of cobalt and nickel on ferroptosis are scant and nearly lacking altogether for mercury and especially lead. Other gaps in the field include limited studies on the role of metal speciation in ferroptosis and the critical cellular targets. Although further detailed studies are required, it seems reasonable to propose even at this early stage that ferroptosis may play a significant role in metal toxicity, and its modulation may be considered as a potential therapeutic tool for the amelioration of metal toxicity.

Meta-analysis of in-vitro cytotoxicity evaluation studies of zinc oxide nanoparticles: Paving way for safer innovations

Nano-based products have shown their daunting presence in several sectors. Among them, Zinc Oxide (ZnO) nanoparticles wangled the reputation of providing "next-generation solutions" and are being utilized in plethora of products. Their widespread application has led to increased exposure of these particles, raising concerns regarding toxicological repercussions to the human health and environment. The diversity, complexity, and heterogeneity in the available literature, along with correlation of befitting attributes, makes it challenging to develop one systematic framework to predict this toxicity. The present study aims at developing predictive modelling framework to tap the prospective features responsible for causing cytotoxicity in-vitro on exposure to ZnO nanoparticles. Rigorous approach was used to mine the information from complete body of evidence published to date. The attributes, features and experimental conditions were systematically extracted to unmask the effect of varied features. 1240 data points from 76 publications were obtained, containing 14 qualitative and quantitative attributes, including physiochemical properties of nanoparticles, cell culture and experimental parameters to perform meta-analysis. For the first time, the efforts were made to investigate the degree of significance of attributes accountable for causing cytotoxicity on exposure to ZnO nanoparticles. We show that in-vitro cytotoxicity is closely related with dose concentration of nanoparticles, followed by exposure time, disease state of the cell line and size of these nanoparticles among other attributes.

Different cellular mechanisms from low- and high-dose zinc oxide nanoparticles-induced heart tube malformation during embryogenesis

With the wide application of nanometer materials in daily life, people pay more attention to the potential toxicity of nanoparticles to human fetal development once the nanoparticles are absorbed into the human body during pregnancy. However, there was no directly solid evidence for ZnO NPs-caused congenital heart defects. Hence, we investigated the effect of ZnO NPs exposure on early cardiogenesis using the chicken/mouse embryo models. First, we showed ZnO NPs reduced H9c2 cell viability in a dose- and time-dependent manner, while cell autophagy was significantly activated too on the same pattern. During early cardiogenesis, ZnO NPs exposure increased the chance of heart tube malformation, while precardiac cell apoptosis rises in the phenotype of closure defect and Bifida. The hypertrophy was also observed in late-stage chicken/mouse survival embryos exposed to ZnO NPs. Apart from cell apoptosis, high-dose ZnO NPs exposure led to massive programmed necrosis, and further experiments verified that ferroptosis remained primarily in ZnO NPs-induced programmed necrosis. We also revealed that the toxicology of low-dose ZnO NPs was mainly featured in the changes of expressions of key genes instead of causing precardiac cell death. MYL2 and CSRP3 could work as the downstream molecules of the above key genes in the context of ZnO NPs exposure to early cardiogenesis based on RNA sequencing. Taken together, this study for the first time revealed the potential risk of heart tube malformation induced by ZnO NPs exposure through different cellular mechanisms, which depended on low- or high-dose ZnO NPs.

Nickel oxide nanoparticles induce apoptosis and ferroptosis in airway epithelial cells via ATF3

Exposure to nickel oxide nanoparticles (NiONPs), which have been widely produced and applied in industry, leads to adverse pulmonary and systemic effects. The aim of this study is to investigate the involvement of apoptosis and ferroptosis in NiONPs-induced acute lung injury (ALI). Intratracheal instillation of NiONPs into mice elevated the levels of pro-inflammatory cytokines, neutrophils, and proteins in the bronchoalveolar lavage fluid, and triggered apoptosis and ferroptosis in the lung tissues. Consistently, NiONPs-induced apoptosis and ferroptosis were observed in in vitro experiments using human lung epithelial cells. Activating transcription factor 3 (ATF3), a stress-inducible transcription factor, was upregulated by NiONPs exposure in both murine lung tissues and human lung epithelial cells. Moreover, human lung epithelial cells with ATF3 deficiency exhibited a lower level of apoptosis and ferroptosis when exposed to NiONPs. Collectively, our findings demonstrated that ATF3 was responsive to NiONPs exposure, and promoted NiONPs-induced apoptosis and ferroptosis in lung epithelial cells, indicating that ATF3 is a potential biomarker and therapeutic target for NiONPs-associated ALI.

Esculetin and Fucoidan Attenuate Autophagy and Apoptosis Induced by Zinc Oxide Nanoparticles through Modulating Reactive Astrocyte and Proinflammatory Cytokines in the Rat Brain

We examined the protective effects of esculetin and fucoidan against the neurotoxicity of ZnO NPs in rats. Ninety rats were divided into nine groups and pre-treated with esculetin or fucoidan 1 h before ZnO NP administration on a daily basis for 2 weeks. Serum and brain homogenates were examined by enzyme-linked immunosorbent assay (ELISA), and neurons, microglia, and astrocytes in the hippocampal region were examined with immunohistochemical analysis. The serum levels of interleukin-1-beta (IL-1β), 3-nitrotyrosine (3-NT), superoxide dismutase (SOD), and 8-hydroxy-2′-deoxyguanosine (8-OHdG) were altered in the ZnO NP treatment groups. Brain IL-1β and TNF-α levels were elevated after ZnO NP administration, and these effects were inhibited by esculetin and fucoidan. SOD, 8-OHdG, and acetylcholinesterase (AChE) levels in the brain were decreased after ZnO NP administration. The brain levels of beclin-1 and caspase-3 were elevated after ZnO NP treatment, and these effects were significantly ameliorated by esculetin and fucoidan. The number of reactive astrocytes measured by counting glial fibrillary acidic protein (GFAP)-positive cells, but not microglia, increased following ZnO NP treatment, and esculetin and fucoidan ameliorated the changes. Esculetin and fucoidan may be beneficial for preventing ZnO NP-mediated autophagy and apoptosis by the modulation of reactive astrocyte and proinflammatory cytokines in the rat brain.

Hyaluronic acid functionalized ZnO nanoparticles co-deliver AS and GOD for synergistic cancer starvation and oxidative damage

Artesunate was reported to have inhibition effect on tumors via amplified oxidative stress while the lack of intratumoral ferrous ions supply greatly hinders its efficacy. Herein, the AS/GOD@HAZnO NPs we proposed could be efficiently taken in by the affinity between hyaluronic acid and the CD44 receptors. DLS and TEM results manifested the nano-size (~ 160 nm) and circular shape of AS/GOD@HAZnO NPs. Due to the acid-responsive degradation, AS/GOD@HAZnO NPs realized responsive release (up to 80%) in acid environment while only 20% was released in neutral medium. The cellular and in vivo experiment showed that co-delivery of AS and GOD via HAZnO NPs could effectively induce the overproduction of ROS and cut the glucose supply of tumor cells, and thus result in efficient cell apoptosis and tumor inhibition.

The role of ferroptosis in organ toxicity

Ferroptosis, an iron-dependent form of programmed cell death, is characterized by iron overload, increased reactive oxygen species (ROS) generation, and depletion of glutathione (GSH) and lipid peroxidation. Lipophilic antioxidants and iron chelators can prevent ferroptosis. GSH-dependent glutathione peroxidase 4 (GPX4) prevents lipid ROS accumulation. Ferroptosis is thought to be initiated through GPX4 inactivation. Moreover, mitochondrial iron overload derived from the degradation of ferritin is involved in increasing ROS generation. Ferroptosis has been suggested to explain the mechanism of action of organ toxicity induced by several drugs and chemicals. Inhibition of ferroptosis may provide novel therapeutic opportunities for treatment and even prevention of such organ toxicities.

Multifunctional MnO2-based nanoplatform-induced ferroptosis and apoptosis for synergetic chemoradiotherapy

Background: Radiosensitizers that can effectively consume glutathione provide broad prospects for enhancing the efficacy and reducing the side effects of radiotherapy. Aim: To explore the potential role of CuS@mSiO₂@MnO₂ nanocomposites in synergetic chemoradiotherapy. Methods: Nanocomposites were characterized by transmission electron microscopy, UV-Vis spectrometry and dynamic light scattering and were loaded with doxorubicin (DOX). The uptake and biodistribution of nanocomposites were observed by CCK8 assay, MRI and confocal laser scanning microscopy. The radiosensitization effect of nanocomposites and nanocomposites/DOX was assessed both in vitro and in vivo. Results: In vitro application of nanocomposites, with an average diameter of 30 nm and ζ-potential of 13.2 ± 0.4 mV, in combination with radiotherapy, depleted glutathione and induced ferroptosis and apoptosis. Nanocomposites/DOX exhibited tumor cell damage in vivo. Conclusion: We propose that this glutathione-depleting nanosystem could be a radiosensitizer as well as a drug transporter.

Bioinformatics Analysis Identifies Potential Ferroptosis Key Genes in the Pathogenesis of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a dangerous neurological disease. The mechanism of ferroptosis in ICH remains unclear. Using bioinformatics analysis, we aimed to identify the key molecules involved in ferroptosis and provide treatment targets for ICH to further explore the mechanism of ferroptosis in ICH. GSE24265 was downloaded from the Gene Expression Omnibus (GEO) dataset and intersected with ferroptosis genes. A total of 45 differentially expressed genes (DEGs) were selected, most of which were involved in the TNF signaling pathway and oxidative stress response. Key modules constructed by the protein–protein interaction (PPI) network analysis and screening of genes related to the TNF signaling pathway led to the confirmation of the following genes of interest: MAPK1, MAPK8, TNFAIP3, ATF4, and SLC2A1. Moreover, MAPK1 was one of the key genes related to TNF signaling and oxidative stress, and it may play an important role in ferroptosis after cerebral hemorrhage. The MAPK1-related molecules included hsa-miR-15b-5P, hsa-miR-93-5P, miR-20b-5p, SNHG16, XIST, AC084219.4, RP11-379K17.11, CTC-444N24.11, GS1-358P8.4, CTB-89H12.4, RP4-773N10.5, and FGD5-AS1. We also generated a hemorrhage rat model, which was used to conduct exercise intervention in ICH rats, and qRT-PCR was used to assess the expression levels of our genes of interest. The mRNA levels after cerebral hemorrhage showed that MAPK1, ATF4, SLC2A1, and TNFAIP3 were upregulated, whereas MAPK8 was downregulated. Treadmill training increased the expression of anti-inflammatory molecules TNFAIP3 and SLC2A1 and reduced the expression of MAPK1, ATF4, and MAPK8, indicating that treadmill training may be utilized as antioxidant therapy to decrease neuronal ferroptosis. The results of this study indicated that the MAPK1-related mRNA–miRNA–lncRNA interaction chain could be potentially employed as a biomarker of the inception and progression of ferroptosis after cerebral hemorrhage.

Stabilization of Nrf2 leading to HO-1 activation protects against zinc oxide nanoparticles-induced endothelial cell death

With the abundant production and wide application of zinc oxide nanoparticles (ZnONPs), the potential health risks of ZnONPs have raised serious concerns. Oxidative stress is recognized as the most important outcome of the toxicity induced by ZnONPs. The Nrf2-Keap1 system and its downstream antioxidative genes are the fundamental protective mechanisms for redox hemeostasis. However, the detailed mechanisms of Nrf2 activation in ZnONPs-treated endothelial cells and murine blood vessels have yet to be elucidated. Herein, we show that Nrf2 was activated and played a negative role in cell death induced by ZnONPs. Moreover, we demonstrate that HO-1 was the most extensively upregulated antioxidative gene-activated by Nrf2. Forced overexpression of HO-1, pharmacological activation of HO-1 with the agonists RTA-408 (omaveloxolone, an FDA-approved drug) and RTA-402 repressed cell death, and treatment with HO-1 antagonist SnPP exacerbated the cell death. Importantly, loss of HO-1 diminished the cytoprotective role induced by Nrf2 in ZnONPs-treated HUVEC cells, indicating that the Nrf2-HO-1 axis was the crucial regulatory mechanism for the antioxidative response in the context of ZnONPs-induced endothelial damage. Mechanistically, we demonstrate that the p62-Keap1 axis was not involved in the activation of Nrf2. Intriguingly, the degradation half-life of Nrf2 in HUVEC cells was increased from less than 1 h under quiescent conditions to approximately 6 h under ZnONPs treatment condition; moreover, ZnONPs treatment induced activation of Nrf2/HO-1 and accumulation of ubiquitin in the aorta ventralis of mouse, suggesting that the ubiquitin-proteasome system had been perturbed, which subsequently led to the stabilization of Nrf2 and activation of HO-1. This study might contribute to a better understanding of ZnONPs-associated toxicity.

Behavioural alterations induced by chronic exposure to 10 nm silicon dioxide nanoparticles

Silicon dioxide nanoparticles (SiO2 NPs) are widely invested in medicine, industry, agriculture, consuming products, optical imaging agents, cosmetics, and drug delivery. However, the toxicity of these NPs on human health and the ecosystem have not been extensively studied and little information is available about their behavioural toxicities. The current study aimed to find out the behavioural alterations that might be induced by chronic exposure to 10 nm SiO2 NPs. BALB/C mice were subjected to 36 injections of SiO2 NPs (2 mg/kg Bw) and subjected to 11 neurobehavioural tests: elevated plus-maze test, elevated zero-maze test, multiradial maze test, open field test, hole-board test, light-dark box test, forced swimming test, tail-suspension test, Morris water-maze test, Y-maze test and multiple T-maze test. Treated mice demonstrated anxiety-like effect, depression tendency, behavioural despair stress, exploration and locomotors activity reduction with error induction in both reference and working memories. The findings may suggest that silica NPs are anxiogenic and could aggravate depression affecting memory, learning, overall activity and exploratory behaviour. Moreover, the findings may indicate that these nanomaterials (NMs) may induce potential oxidative stress in the body leading to neurobehavioural alterations with possible changes in the vital organ including the central nervous system.