Interference in autophagosome fusion by rare earth nanoparticles disrupts autophagic flux and regulation of an interleukin-1β producing inflammasome

Long Noncoding RNA NR_030777 Alleviates Cobalt Nanoparticles-Induced Neurodegenerative Damage by Promoting Autophagosome-Lysosome Fusion

Potential exposure to cobalt nanoparticles (CoNPs) occurs in various fields, including hard alloy industrial production, the increasing use of new energy lithium-ion batteries, and millions of patients with metal-on-metal joint prostheses. Evidence from human, animal, and in vitro experiments suggests a close relationship between CoNPs and neurotoxicity. However, a systematic assessment of central nervous system (CNS) impairment due to CoNPs exposure and the underlying molecular mechanisms is lacking. In this study, we found that CoNPs induced neurodegenerative damage both in vivo and in vitro, including cognitive impairment, β-amyloid deposition and Tau hyperphosphorylation. CoNPs promoted the formation of autophagosomes and impeding autophagosomal-lysosomal fusion in vivo and in vitro, leading to toxic protein accumulation. Moreover, CoNPs exposure reduced the level of transcription factor EB (TFEB) and the abundance of lysosome, causing a blockage in autophagosomal-lysosomal fusion. Interestingly, overexpression of long noncoding RNA NR_030777 mitigated CoNPs-induced neurodegenerative damage in both in vivo and in vitro models. Fluorescence in situ hybridization assay revealed that NR_030777 directly binds and stabilizes TFEB mRNA, alleviating the blockage of autophagosomal-lysosomal fusion and ultimately restoring neurodegeneration induced by CoNPs in vivo and in vitro. In summary, our study demonstrates that autophagic dysfunction is the main toxic mechanism of neurodegeneration upon CoNPs exposure and NR_030777 plays a crucial role in CoNPs-induced autophagic dysfunction. Additionally, the proposed adverse outcome pathway contributes to a better understanding of CNS toxicity assessment of CoNPs.

Virus-Shaped Mesoporous Silica Nanostars to Improve the Transport of Drugs across the Blood-Brain Barrier

Conditions affecting the brain are the second leading cause of death globally. One of the main challenges for drugs targeting brain diseases is passing the blood-brain barrier (BBB). Here, the effectiveness of mesoporous silica nanostars (MSiNSs) with two different spike lengths to cross an in vitro BBB multicellular model was evaluated and compared to spherical nanoparticles (MSiNP). A modified sol-gel single-micelle epitaxial growth was used to produce MSiNS, which showed no cytotoxicity or immunogenicity at concentrations of up to 1 μg mL-1 in peripheral blood mononuclear and neuronal cells. The nanostar MSiNS effectively penetrated the BBB model after 24 h, and MSiNS-1 with a shorter spike length (9 ± 2 nm) crossed the in vitro BBB model more rapidly than the MSiNS-2 with longer spikes (18 ± 4 nm) or spherical MSiNP at 96 h, which accumulated in the apical and basolateral sides, respectively. Molecular dynamic simulations illustrated an increase in configurational flexibility of the lipid bilayer during contact with the MSiNS, resulting in wrapping, whereas the MSiNP suppressed membrane fluctuations. This work advances an effective brain drug delivery system based on virus-like shaped MSiNS for the treatment of different brain diseases and a mechanism for their interaction with lipid bilayers.

A phosphatase-like nanomaterial promotes autophagy and reprograms macrophages for cancer immunotherapy

Macrophages are plastic and play a key role in the maintenance of tissue homeostasis. In cancer progression, macrophages also take part in all processes, from initiation to progression, to final tumor metastasis. Although energy deprivation and autophagy are widely used for cancer therapy, most of these strategies do not target macrophages, resulting in undesired effects and unsatisfactory outcomes for cancer immunotherapy. Herein, we developed a lanthanum nickel oxide (LNO) nanozyme with phosphatase-like activity for ATP hydrolysis. Meanwhile, the autophagy of macrophages induced by LNO promotes the polarization of macrophages from M2-like macrophages (M2) to M1-like macrophages (M1) and reduces tumor-associated macrophages in tumor-bearing mice, exhibiting the capability of killing tumor-associated macrophages and antitumor effects in vivo. Furthermore, pre-coating the surface of LNO with a myeloid cell membrane significantly enhanced antitumor immunity. Our findings demonstrate that phosphatase-like nanozyme LNO can specifically induce macrophage autophagy, which improves therapeutic efficacy and offers valuable strategies for cancer immunotherapy.

ROS-mediated NRF2/p-ERK1/2 signaling-involved mitophagy contributes to macrophages activation induced by CdTe quantum dots

Cadmium telluride (CdTe) quantum dots (QDs) have garnered significant attention for tumor imaging due to their exceptional properties. However, there remains a need for further investigation into their potential toxicity mechanisms and corresponding enhancements. Herein, CdTe QDs were observed to accumulate in mouse liver, leading to a remarkable overproduction of IL-1β and IL-6. Additionally, there was evidence of macrophage infiltration and activation following exposure to 12.5 μmol/kg body weight of QDs. To elucidate the underlying mechanism of macrophage activation, CdTe QDs functionalized with 3-mercaptopropionic acid (MPA) were utilized. In vitro experiments revealed that 1.0 μM MPA-CdTe QDs activated PINK1-dependent mitophagy in RAW264.7 macrophages. Critically, the autophagic flux remained unimpeded, as demonstrated by the absence of p62 accumulation, LC3 turnover assay results, and successful fusion of autophagosomes with lysosomes. Mechanically, QDs increased reactive oxygen species (ROS) and mitoROS by damaging both mitochondria and lysosomes. ROS, in turn, inhibited NRF2, resulting in the phosphorylation of ERK1/2 and subsequent activation of mitophagy. Notably, 1.0 μM QDs disrupted lysosomes but autophagic flux was not impaired. Eventually, the involvement of the ROS-NRF2-ERK1/2 pathway-mediated mitophagy in the increase of IL-1β and IL-6 in macrophages was confirmed using Trolox, MitoTEMPO, ML385, specific siRNAs, and lentivirus-based interventions. This study innovatively revealed the pro-inflammatory rather than anti-inflammatory role of mitophagy in nanotoxicology, shedding new light on the mechanisms of mitochondrial disorders induced by QDs and identifying several molecular targets to comprehend the toxicological mechanisms of CdTe QDs.

Determining toxicity of europium oxide nanoparticles in immune cell components and hematopoiesis in dominant organs in mice: Role of lysosomal fluid interaction

Extensive application of rare earth element oxide nanoparticles (REE NPs) has raised a concern over the possible toxic health effects after human exposure. Once entering the body, REE NPs are primarily processed by phagocytes in particular macrophages and undergo biotic phosphate complexation in lysosomal compartment. Such biotransformation affects the target organs and in vivo fate of REE NPs after escaping the lysosomes. However, the immunomodulatory effects of intraphagolysosomal dissolved REE NPs remains insufficient. Here, europium oxide (Eu2O3) NPs were pre-incubated with phagolysosomal simulant fluid (PSF) to mimic the biotransformation of europium oxide (p-Eu2O3) NPs under acid phagolysosome conditions. We investigated the alteration in immune cell components and the hematopoiesis disturbance on adult mice after intravenous administration of Eu2O3 NPs and p-Eu2O3 NPs. Our results indicated that the liver and spleen were the main target organs for Eu2O3 NPs and p-Eu2O3 NPs. Eu2O3 NPs had a much higher accumulative potential in organs than p-Eu2O3 NPs. Eu2O3 NPs induced more alterations in immune cells in the spleen, while p-Eu2O3 NPs caused stronger response in the liver. Regarding hematopoietic disruption, Eu2O3 NPs reduced platelets (PLTs) in peripheral blood, which might be related to the inhibited erythrocyte differentiation in the spleen. By contrast, p-Eu2O3 NPs did not cause significant disturbance in peripheral PLTs. Our study demonstrated that the preincubation with PSF led to a distinct response in the immune system compared to the pristine REE NPs, suggesting that the potentially toxic effects induced by the release of NPs after phagocytosis should not be neglected, especially when evaluating the safety of NPs application in vivo.

Zinc oxide nanoparticles exacerbate skin epithelial cell damage by upregulating pro-inflammatory cytokines and exosome secretion in M1 macrophages following UVB irradiation-induced skin injury

BACKGROUND

Zinc oxide nanoparticles (ZnONPs) are common materials used in skin-related cosmetics and sunscreen products due to their whitening and strong UV light absorption properties. Although the protective effects of ZnONPs against UV light in intact skin have been well demonstrated, the effects of using ZnONPs on damaged or sunburned skin are still unclear. In this study, we aimed to reveal the detailed underlying mechanisms related to keratinocytes and macrophages exposed to UVB and ZnONPs.

RESULTS

We demonstrated that ZnONPs exacerbated mouse skin damage after UVB exposure, followed by increased transepidermal water loss (TEWL) levels, cell death and epithelial thickness. In addition, ZnONPs could penetrate through the damaged epithelium, gain access to the dermis cells, and lead to severe inflammation by activation of M1 macrophage. Mechanistic studies indicated that co-exposure of keratinocytes to UVB and ZnONPs lysosomal impairment and autophagy dysfunction, which increased cell exosome release. However, these exosomes could be taken up by macrophages, which accelerated M1 macrophage polarization. Furthermore, ZnONPs also induced a lasting inflammatory response in M1 macrophages and affected epithelial cell repair by regulating the autophagy-mediated NLRP3 inflammasome and macrophage exosome secretion.

CONCLUSIONS

Our findings propose a new concept for ZnONP-induced skin toxicity mechanisms and the safety issue of ZnONPs application on vulnerable skin. The process involved an interplay of lysosomal impairment, autophagy-mediated NLRP3 inflammasome and macrophage exosome secretion. The current finding is valuable for evaluating the effects of ZnONPs for cosmetics applications.

Ferroptosis Induced by Pollutants: An Emerging Mechanism in Environmental Toxicology

Environmental pollutants have been recognized for their ability to induce various adverse outcomes in both the environment and human health, including inflammation, apoptosis, necrosis, pyroptosis, and autophagy. Understanding these biological mechanisms has played a crucial role in risk assessment and management efforts. However, the recent identification of ferroptosis as a form of programmed cell death has emerged as a critical mechanism underlying pollutant-induced toxicity. Numerous studies have demonstrated that fine particulates, heavy metals, and organic substances can trigger ferroptosis, which is closely intertwined with lipid, iron, and amino acid metabolism. Given the growing evidence linking ferroptosis to severe diseases such as heart failure, chronic obstructive pulmonary disease, liver injury, Parkinson's disease, Alzheimer's disease, and cancer, it is imperative to investigate the role of pollutant-induced ferroptosis. In this review, we comprehensively analyze various pollutant-induced ferroptosis pathways and intricate signaling molecules and elucidate their integration into the driving and braking axes. Furthermore, we discuss the potential hazards associated with pollutant-induced ferroptosis in various organs and four representative animal models. Finally, we provide an outlook on future research directions and strategies aimed at preventing pollutant-induced ferroptosis. By enhancing our understanding of this novel form of cell death and developing effective preventive measures, we can mitigate the adverse effects of environmental pollutants and safeguard human and environmental health.

The deposition of lanthanum carbonate may activate macrophages to induce gastrointestinal mucosal injury in patients with chronic kidney disease: an in vitro caco-2/THP-1 macrophage coculture model study

The aim of this study was to investigate the effect and possible underlying mechanism of La2(CO3)3 deposition on GI mucosal inflammation. Our results showed that La2(CO3)3 can dissolve in artificial gastric fluids and form lanthanum phosphate (LaPO4) precipitates with an average size of about 1 μm. To mimic the intestinal mucosa and epithelial barrier, we established a Caco-2/THP-1 macrophage coculture model and a Caco-2 monoculture model, respectively. Our findings demonstrated that the medium of THP-1 macrophages stimulated by LaPO4 particles can damage the Caco-2 monolayer integrity in the coculture model, while the particles themselves had no direct impact on the Caco-2 monolayer integrity in the monoculture model. We measured values of trans-epithelial electrical resistance and detected images using a laser scanning confocal microscope. These results indicate that continuous stimulation of LaPO4 particles on macrophages can lead to a disruption of intestinal epithelium integrity. In addition, LaPO4 particles could stimulate THP-1 macrophages to secrete both IL-1β and IL-8. Although LaPO4 particles can also promote Caco-2 cells to secrete IL-8, the secretion was much lower than that produced by THP-1 macrophages. In summary, the deposition of La2(CO3)3 has been shown to activate macrophages and induce damage to intestinal epithelial cells, which may exacerbate inflammation in patients with chronic kidney disease. Therefore, patients taking lanthanum carbonate, especially those with gastrointestinal mucosal inflammation, should be mindful of the potential for drug deposition in the GI system.

Macrophage-based therapeutic approaches for cardiovascular diseases

Despite the advances in treatment options, cardiovascular disease (CVDs) remains the leading cause of death over the world. Chronic inflammatory response and irreversible fibrosis are the main underlying pathophysiological causes of progression of CVDs. In recent decades, cardiac macrophages have been recognized as main regulatory players in the development of these complex pathophysiological conditions. Numerous approaches aimed at macrophages have been devised, leading to novel prospects for therapeutic interventions. Our review covers the advancements in macrophage-centric treatment plans for various pathologic conditions and examines the potential consequences and obstacles of employing macrophage-targeted techniques in cardiac diseases.

Pulmonary Surfactant Homeostasis Dysfunction Mediates Multiwalled Carbon Nanotubes Induced Lung Fibrosis via Elevating Surface Tension

Multiwalled carbon nanotubes (MWCNTs) have been widely used in many disciplines and raised great concerns about their negative health impacts, especially environmental and occupational exposure. MWCNTs have been reported to induce fibrotic responses; however, the underlying mechanisms remain largely veiled. Here, we reported that MWCNTs inhalation induced lung fibrosis together with decreased lung compliance, increased elastance in the mice model, and elevated surface tension in vitro. Specifically, MWCNTs increased surface tension by impairing the function of the pulmonary surfactant. Mechanistically, MWCNTs induced lamellar body (LB) dysfunction through autophagy dysfunction, which then leads to surface tension elevated by pulmonary surfactant dysfunction in the context of lung fibrosis. This is a study to investigate the molecular mechanism of MWCNTs-induced lung fibrosis and focus on surface tension. A direct mechanistic link among impaired LBs, surface tension, and fibrosis has been established. This finding elucidates the detailed molecular mechanisms of lung fibrosis induced by MWCNTs. It also highlights that pulmonary surfactants are expected to be potential therapeutic targets for the prevention and treatment of lung fibrosis induced by MWCNTs.

Targeting Lysosome for Enhanced Cancer Photodynamic/Photothermal Therapy in a "One Stone Two Birds" Pattern

Highly immunogenic programmed death of tumor cells, such as immunogenic cell death (ICD) and pyroptosis, strengthens antitumor responses and thus represents a promising target for cancer immunotherapy. However, the development of ICD and pyroptosis inducers remains challenging, and their efficiency is typically compromised by self-protective autophagy. Here, we report a potent ICD and pyroptosis-inducing strategy by coupling combined photodynamic/photothermal therapy (PTT/PDT) to biological processes in cancer cells. For this purpose, we rationally synthesize a lysosomal-targeting boron-dipyrromethene dimer (BDPd) with intense NIR absorption/emission, high reactive oxygen species (ROS) yield, and photothermal abilities, which can be self-assembled with Pluronic F127, producing lysosomal-acting nanomicelles (BDPd NPs) to facilitate cancer cell internalization of BDPd and generation of intracellular ROS. Owing to the favorable lysosomal-targeting ability of the morpholine group on BDPd, the intracellular BDPd NPs can accumulate in the lysosome and induce robust lysosomal damage in cancer cells upon 660 nm laser irradiation, which results in the synergetic induction of pyroptosis and ICD via activating NLRP3/GSDMD and caspase-3/GSDME pathways simultaneously. More importantly, PTT/PDT-induced self-protective autophagic degradation was blocked due to the dysfunction of lysosomes. Either intratumorally or intravenously, the injected BDPd NPs could markedly inhibit the growth of established tumor tissues upon laser activation, provoke local and systemic antitumor immune responses, and prolong the survival time in the mouse triple-negative breast cancer model. Collectively, this work represents a promising strategy to boost the therapeutic potential of PTT/PDT by coupling phototherapeutic reagents with the subcellular organelles, creating a "one stone two birds" pattern.

Autophagy inhibitors for cancer therapy: Small molecules and nanomedicines

Autophagy is a conserved process in which the cytosolic materials are degraded and eventually recycled for cellular metabolism to maintain homeostasis. The dichotomous role of autophagy in pathogenesis is complicated. Accumulating reports have suggested that cytoprotective autophagy is responsible for tumor growth and progression. Autophagy inhibitors, such as chloroquine (CQ) and hydroxychloroquine (HCQ), are promising for treating malignancies or overcoming drug resistance in chemotherapy. With the rapid development of nanotechnology, nanomaterials also show autophagy-inhibitory effects or are reported as the carriers delivering autophagy inhibitors. In this review, we summarize the small-molecule compounds and nanomaterials inhibiting autophagic flux as well as the mechanisms involved. The nanocarrier-based drug delivery systems for autophagy inhibitors and their distinct advantages are also described. The progress of autophagy inhibitors for clinical applications is finally introduced, and their future perspectives are discussed.

Lysosomal nanotoxicity: Impact of nanomedicines on lysosomal function

Although several nanomedicines got clinical approval over the past two decades, the clinical translation rate is relatively small so far. There are many post-surveillance withdrawals of nanomedicines caused by various safety issues. For successful clinical advancement of nanotechnology, it is of unmet need to realize cellular and molecular foundation of nanotoxicity. Current data suggest that lysosomal dysfunction caused by nanoparticles is emerging as the most common intracellular trigger of nanotoxicity. This review analyzes prospect mechanisms of lysosomal dysfunction-mediated toxicity induced by nanoparticles. We summarized and critically assessed adverse drug reactions of current clinically approved nanomedicines. Importantly, we show that physicochemical properties have great impact on nanoparticles interaction with cells, excretion route and kinetics, and subsequently on toxicity. We analyzed literature on adverse reactions of current nanomedicines and hypothesized that adverse reactions might be linked with lysosomal dysfunction caused by nanomedicines. Finally, from our analysis it becomes clear that it is unjustifiable to generalize safety and toxicity of nanoparticles, since different particles possess distinct toxicological properties. We propose that the biological mechanism of the disease progression and treatment should be central in the optimization of nanoparticle design.

Effects of short-term high-concentration exposure to PM2.5 on pulmonary tissue damage and repair ability as well as innate immune events

Short-term heavy air pollution still occurs frequently worldwide, especially during the winter heating period in some developing countries, which is usually accompanied by the temporary explosive growth of PM_2.5. The pulmonary damage caused by PM_2.5 exposure has been determined, but there have been few studies on the repair ability after the cessation of exposure and the important role of innate immune events. This study established a short-term (30 days) high-concentration (15 mg/kg body weight) PM_2.5 exposure and recovery (15 days of exposure cessation) model by intratracheal instillation. The results showed that short-term PM_2.5 exposure increased the content of collagen fiber in rat lung tissue, which was significantly repaired after recovery by 15 days of exposure cessation. Meanwhile, exposure to PM_2.5 also caused changes in lung epithelial function, macrophage polarization and cell autophagy function. Most of these changes could be restored or reversed to a certain extent after recovery. However, there were also some biomarkers, including CLDN18.1, SP-A, SP-D, iNOS, CD206, Beclin1, p62 and LC3B, that were still significantly different between the exposure and control groups after recovery, suggesting that some toxic effects, especially epithelial function damage, were not completely repaired. In addition, there was a significant correlation between pulmonary fibrosis and innate immunity. The present study demonstrated that short-term high-concentration exposure to PM_2.5 could cause temporary lung tissue damage and related innate immune events in rats, and the repair ability existed after the cessation of exposure, but part of the damage that required special attention still persisted.

Die hard: cell death mechanisms and their implications in nanotoxicology

Cell death is a fundamental biological process, and its fine-tuned regulation is required for life. However, the complexity of regulated cell death is often reduced to a matter of live-dead discrimination. Here, we provide a perspective on programmed or regulated cell death, focusing on apoptosis, pyroptosis, necroptosis, and ferroptosis (the latter three cell death modalities are examples of regulated necrosis). We also touch on other, recently described manifestations of (pathological) cell death including cuproptosis. Furthermore, we address how engineered nanomaterials impact on regulated cell death. We posit that an improved understanding of nanomaterial-induced perturbations of cell death may allow for a better prediction of the consequences of human exposure and could also yield novel approaches by which to mitigate these effects. Finally, we provide examples of the harnessing of nanomaterials to achieve cancer cell killing through the induction of regulated cell death.

Modulating Nanozyme-Based Nanomachines via Microenvironmental Feedback for Differential Photothermal Therapy of Orthotopic Gliomas

Gliomas are common and refractory primary tumors closely associated with the fine structures of the brain. Photothermal therapy (PTT) has recently shown promise as an effective treatment for gliomas. However, nonspecific accumulation of photothermal agents may affect adjacent normal brain structures, and the inflammatory response induced during PTT may result in an increased risk of brain tumor recurrence or metastasis. Here, the design and fabrication of an intelligent nanomachine is reported based on Gd₂ O₃ @Ir/TMB-RVG29 (G@IT-R) hybrid nanomaterials. These nanomaterials enable tumor-specific PTT and eliminate inflammation to protect normal brain tissue. The mechanism involves the rabies virus glycopeptide-29 peptide (RVG29) passing through the blood-brain barrier (BBB) and targeting gliomas. In the tumor microenvironment, Ir nanozymes can act as logic control systems to trigger chromogenic reaction amplification of 3,3',5,5'-tetramethylbenzidine (TMB) for tumor-specific PTT, whereas in normal brain tissues, they scavenge reactive oxygen species (ROS) generated by poor therapy and function as protective agents. Autophagy inhibition of Gd₂ O₃ enables excellent photothermal therapeutic effects on orthotopic gliomas and protection against inflammation in normal cells. The results of this study may prove useful in developing highly efficient nanomedicines for glioma treatment.

Mechanisms of cell injury induced by inhaled molybdenum trioxide nanoparticles in Golden Syrian Hamsters

Molybdenum trioxide nanoparticles (MoO₃ NPs) are extensively used in the biomedical, agricultural, and engineering fields that may increase exposure and adverse health effects to the human population. The purpose of this study is to evaluate a possible molecular mechanism leading to cell damage and death following pulmonary exposure to inhaled MoO₃ NPs. Animals were separated into four groups: two control groups exposed to room air or aerosolized water and two treated groups exposed to aerosolized MoO₃ NPs with a concentration of 5 mg/m³ NPs (4 h/day for eight days) and given a one-day (T-1) or seven-day (T-7) recovery period post exposure. Pulmonary toxicity was evaluated with total and differential cell counts. Increases were seen in total cell numbers, neutrophils, and multinucleated macrophages in the T-1 group, with increases in lymphocytes in the T-7 group (*P < 0.05). To evaluate the mechanism of toxicity, protein levels of Beclin-1, light chain 3 (LC3)-I/II, P-62, cathepsin B, NLRP3, ASC, caspase-1, interleukin (IL)-1β, and tumor necrosis factor-α (TNF-α) were assessed in lung tissue. Immunoblot analyses indicated 1.4- and 1.8-fold increases in Beclin-1 in treated groups (T-1 and T-7, respectively, *P < 0.05), but no change in protein levels of LC3-I/II in either treated group. The levels of cathepsin B were 2.8- and 2.3-fold higher in treated lungs (T-1 and T-7, respectively, *P < 0.05), the levels of NLRP3 had a fold increase of 2.5 and 3.6 (T-1 *P < 0.05, T-7 **P < 0.01, respectively), and the levels of caspase-1 indicated a 3.8- and 3.0-fold increase in treated lungs (T-1 and T-7, respectively, *P < 0.05). Morphological changes were studied using light and electron microscopy showing alterations to airway epithelium and the alveoli, along with particle internalization in macrophages. The results from this study may indicate that inhalation exposure to MoO₃ NPs may interrupt the autophagic flux and induce cytotoxicity and lung injury through pyroptosis cell death and activation of caspase-1.

Diverse Pathways of Engineered Nanoparticle-Induced NLRP3 Inflammasome Activation

With the rapid development of engineered nanomaterials (ENMs) in biomedical applications, their biocompatibility and cytotoxicity need to be evaluated properly. Recently, it has been demonstrated that inflammasome activation may be a vital contributing factor for the development of biological responses induced by ENMs. Among the inflammasome family, NLRP3 inflammasome has received the most attention because it directly interacts with ENMs to cause the inflammatory effects. However, the pathways that link ENMs to NLRP3 inflammasome have not been thoroughly summarized. Thus, we reviewed recent findings on the role of major ENMs properties in modulating NLRP3 inflammasome activation, both in vitro and in vivo, to provide a better understanding of the underlying mechanisms. In addition, the interactions between ENMs and NLRP3 inflammasome activation are summarized, which may advance our understanding of safer designs of nanomaterials and ENM-induced adverse health effects.

Triterpenoid saponins of Ilex pubescens against TNF-α induced inflammation and apoptosis in human umbilical vein endothelial cells via autophagy pathway

OBJECTIVES

Triterpenoid saponins of Ilex pubescens (IPTS), the main active components of Ilex pubescens, has a therapeutic effect on atherosclerosis (AS). The ingredients in IPTS that could be intracellularly transported by human umbilical vein endothelial cells (HUVECs) may play an essential role in AS. This study attempted to explore its mechanism from the perspectives of HUVECs' inflammation, apoptosis, and autophagy.

METHODS

By using a tumour necrosis factor-α (TNF-α)-induced HUVECs injury model, cell viability and the expression of intercellular adhesion molecule 1 (ICAM1), matrix metalloproteinase 9 (MMP9), cleave-caspase-3 and cleave-caspase-9, in combination with the results of flow cytometry, JC-1 and Hoechst 33258 staining were investigated to evaluate the anti-inflammatory and anti-apoptotic impact effects of IPTS on HUVECs. Afterwards, the expression of microtubule-associated proteins light chain 3II (LC3II) and sequestosome 1 (p62) was determined to test the effect of IPTS on autophagy. Finally, by adding an autophagy inhibitor 3-methyladenine (3-MA), we investigated whether IPTS exerts anti-inflammatory and anti-apoptotic effects through the autophagy pathway.

KEY FINDINGS

We firstly demonstrated that pretreatment with IPTS could increase the cell viability, maintain the cell morphology and reduce TNF-α-induced inflammation and apoptosis of HUVECs. Moreover, IPTS pretreatment was proved to raise the expression of LC3II /LC3I while decreasing the expression of p62, which indicated that IPTS could activate HUVECs' autophagy. IPTS has been shown for the first time to exert anti-inflammatory and anti-apoptotic effects through autophagy and thereby resisting TNF-α-induced inflammatory injury of HUVECs.

CONCLUSIONS

This study preliminarily confirmed that IPTS ameliorated HUVECs' inflammation and apoptosis by increasing autophagy.

Size- and shape-dependent cytotoxicity of nano-sized Zr-based porphyrinic metal-organic frameworks to macrophages

The wide utilization of nano-sized metal-organic frameworks (NMOFs) leads to inevitable health risks to humans. Previous studies on health risks of NMOFs mainly focus on the cytotoxic tests of typical NMOFs，but lack sufficient studies on the effects of physiochemical characteristics of NMOFs on the cytotoxicity and the related mechanisms. Here, four kinds of Zr-based porphyrinic NMOFs (PCNs), including spherical 30, 90, and 180 nm PCN-224 and rod-like 90 nm PCN-222, were taken as a proof of the concept to investigate the effects of the size and shape of NMOFs on the cytotoxicity and related mechanisms to macrophages. The 30 nm spherical PCN-224 induced significant rupture of cell membrane and dissolved in lysosome, leading to the most significant cell necrosis among the studied other nano-sized PCNs. However, other studied PCNs showed insignificant membrane rupture and their dissolution in lysosome. Furthermore, the 90 nm-sized PCN-224 led to much more significant cell necrosis by inducing lysosome damage and inhibiting of autophagy flux than the rod-like 90 nm PCN-222. These findings reveal the size- and shape-dependent cytotoxicity of PCNs and the related mechanisms and are helpful to the assessment of the potential health risks of NMOFs and the safe application of NMOFs.

Inflammation and accompanied disrupted hematopoiesis in adult mouse induced by rare earth element nanoparticles

Rare earth element nanoparticles (REE NPs) or agents have been used extensively in various fields. Human exposure to REE NPs is an increasing concern. To date, REE NP-mediated comprehensive immune responses after incorporation into the body remain unclear. In our study, using gadolinium oxide NPs (Gd₂O₃) as a typical REE NP, we systematically investigated immune responses in vivo. The liver and spleen were the main sites where Gd₂O₃ retained and accumulated, while Gd₂O₃ content per unit tissue mass in the spleen was 4.4 times higher than that in the liver. Gd₂O₃ increased the number of monocyte-derived macrophages and myeloid-derived dendritic cells (M-DCs) in the liver. In the spleen, Gd₂O₃ caused infiltration of neutrophils, M-DCs, and B cells. The accumulation of Gd₂O₃ in the liver or spleen also contributed to an increased concentration of cytokines in peripheral blood. In both the bone marrow and spleen, Gd₂O₃ led to increased populations of hematopoietic stem cells (HSCs), multipotent progenitors, and common lymphoid progenitors. Compared to the decreased monocytes in peripheral blood on day 2, a significant decrease of circulating lymphocytes on day 7 was still observed, suggesting the exposure duration led to variable effects. This might be explained by the sustained accumulation of Gd₂O₃ in the liver and spleen. Together, our study systemically depicted the alterations in mature immune alterations together with hematopoiesis in both myeloid and lymphoid lineages induced by Gd₂O₃ exposure. Our findings will facilitate a comprehensive understanding of the interactions of immune system with REE NPs in vivo.

NOX2-mediated reactive oxygen species are double-edged swords in focal cerebral ischemia in mice

BACKGROUND

Reactive oxygen species (ROS) often promote acute brain injury after stroke, but their roles in the recovery phase have not been well studied. We tested the hypothesis that ROS activity mediated by NADPH oxidase 2 (NOX2) contributes to acute brain injury but promotes functional recovery during the delayed phase, which is linked with neuroinflammation, autophagy, angiogenesis, and the PI3K/Akt signaling pathway.

METHODS

We used the NOX2 inhibitor apocynin to study the role of NOX2 in brain injury and functional recovery in a middle cerebral artery occlusion (MCAO) stroke mouse model. Infarct size, neurological deficits and behavior were evaluated on days 3, 7, 10 and 14 after reperfusion. In addition, dynamic NOX2-induced ROS levels were measured by dihydroethidium (DHE) staining. Autophagy, inflammasomes, and angiogenesis were measured by immunofluorescence staining and western blotting. RNA sequencing was performed, and bioinformatics technology was used to analyze differentially expressed genes (DEGs), as well as the enrichment of biological functions and signaling pathways in ischemia penumbra at 7 days after reperfusion. Then, Akt pathway-related proteins were further evaluated by western blotting.

RESULTS

Our results showed that apocynin injection attenuated infarct size and mortality 3 days after stroke but promoted mortality and blocked functional recovery from 5 to 14 days after stroke. DHE staining showed that ROS levels were increased at 3 days after reperfusion and then gradually declined in WT mice, and these levels were significantly reduced by the NOX2 inhibitor apocynin. RNA-Seq analysis indicated that apocynin activated the immune response under hypoxic conditions. The immunofluorescence and western blot results demonstrated that apocynin inhibited the NLRP3 inflammasome and promoted angiogenesis at 3 days but promoted the NLRP3 inflammasome and inhibited angiogenesis at 7 and 14 days after stroke, which was mediated by regulating autophagy activation. Furthermore, RNA-Seq and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that apocynin injection resulted in PI3K-Akt signaling pathway enrichment after 7 days of MCAO. We then used an animal model to show that apocynin decreased the protein levels of phosphorylated PI3K and Akt and NF-κB p65, confirming that the PI3K-Akt-NF-κB pathway is involved in apocynin-mediated activation of inflammation and inhibition of angiogenesis.

CONCLUSIONS

NOX2-induced ROS production is a double-edged sword that exacerbates brain injury in the acute phase but promotes functional recovery. This effect appears to be achieved by inhibiting NLRP3 inflammasome activation and promoting angiogenesis via autophagy activation.

Use of dissociation degree in lysosomes to predict metal oxide nanoparticle toxicity in immune cells: Machine learning boosts nano-safety assessment

Potential immune responses resulting from exposure to metal oxide nanoparticles (MeONPs) have been the subject of intensive discussion in the last decade. Despite the extensive use of MeONPs in several applications, their toxic effects on immune cells have rarely been predicted in silico because of the complexity of immune responses and the complicated properties of MeONPs. In the present study, machine learning (ML) methods coupled with high-throughput in vitro bioassays were used to develop models for predicting the toxicity of MeONPs in immune cells. An ML model with a high prediction accuracy (97% and 96% in the training and test sets, respectively) was constructed by resolving the class imbalance problem in training and applying an ensembled algorithm. Further, to verify the model, MeONPs outside the scope of the datasets were selected to examine their cytotoxicity experimentally. The model was validated against independent MeONPs, with an accuracy of 91%. ML methods coupled with intracellular imaging revealed that the toxic ions released in the lysosome were an important determinant of toxicity in immune cells. Furthermore, ζ-potential, electronegativity, and size are crucial factors for predicting nanotoxicity. We believe the established modeling framework will provide useful insights for designing and applying safe nanoparticles and facilitating decision-making for environmental and health protection.

TFEB-lysosome pathway activation is associated with different cell death responses to carbon quantum dots in Kupffer cells and hepatocytes

Background

Carbon dot has been widely used in biomedical field as a kind of nanomaterial with low toxicity and high biocompatibility. CDs has demonstrated its unique advantages in assisted drug delivery, target diagnosis and targeted therapy with its small size and spontaneous fluorescence. However, the potential biosafety of CDs cannot be evaluated. Therefore, we focused on the study of liver, the target organ involved in CDs metabolism, to evaluate the risk of CDs in vitro.

Methods and results

Liver macrophage KUP5 cells and normal liver cells AML12 cells were incubated in CDs at the same concentration for 24 h to compare the different effects under the same exposure conditions. The study found that both liver cell models showed ATP metabolism disorder, membrane damage, autophagosome formation and lysosome damage, but the difference was that, KUP5 cells exhibited more serious damage than AML12 cells, suggesting that immunogenic cell type is particularly sensitive to CDs. The underlying mechanism of CDs-induced death of the two hepatocyte types were also assessed. In KUP5 cells, death was caused by inhibition of autophagic flux caused by autophagosome accumulation, this process that was reversed when autophagosome accumulation was prevented by 3-MA. AML12 cells had no such response, suggesting that the accumulation of autophagosomes caused by CDs may be specific to macrophages.

Conclusion

Activation of the TFEB-lysosome pathway is important in regulating autophagy and apoptosis. The dual regulation of ERK and mTOR phosphorylation upstream of TFEB influences the death outcome of AML12 cells. These findings provide a new understanding of how CDs impact different liver cells and contribute to a more complete toxicological safety evaluation of CDs.

Understanding Nanomaterial-Liver Interactions to Facilitate the Development of Safer Nanoapplications

Nanomaterials (NMs) are widely used in commercial and medical products, such as cosmetics, vaccines, and drug carriers. Exposure to NMs via various routes such as dermal, inhalation, and ingestion has been shown to gain access to the systemic circulation, resulting in the accumulation of NMs in the liver. The unique organ structures and blood flow features facilitate the liver sequestration of NMs, which may cause adverse effects in the liver. Currently, most in vivo studies are focused on NMs accumulation at the organ level and evaluation of the gross changes in liver structure and functions, however, cell-type-specific uptake and responses, as well as the molecular mechanisms at cellular levels leading to effects at organ levels are lagging. Herein, the authors systematically review diverse interactions of NMs with the liver, specifically on major liver cell types including Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), hepatic stellate cells (HSCs), and hepatocytes as well as the detailed molecular mechanisms involved. In addition, the knowledge gained on nano-liver interactions that can facilitate the development of safer nanoproducts and nanomedicine is also reviewed.

Rare earth smart nanomaterials for bone tissue engineering and implantology: Advances, challenges, and prospects

Bone grafts or prosthetic implant designing for clinical application is challenging due to the complexity of integrated physiological processes. The revolutionary advances of nanotechnology in the biomaterial field expedite and endorse the current unresolved complexity in functional bone graft and implant design. Rare earth (RE) materials are emerging biomaterials in tissue engineering due to their unique biocompatibility, fluorescence upconversion, antimicrobial, antioxidants, and anti-inflammatory properties. Researchers have developed various RE smart nano-biomaterials for bone tissue engineering and implantology applications in the past two decades. Furthermore, researchers have explored the molecular mechanisms of RE material-mediated tissue regeneration. Recent advances in biomedical applications of micro or nano-scale RE materials have provided a foundation for developing novel, cost-effective bone tissue engineering strategies. This review attempted to provide an overview of RE nanomaterials' technological innovations in bone tissue engineering and implantology and summarized the osteogenic, angiogenic, immunomodulatory, antioxidant, in vivo bone tissue imaging, and antimicrobial properties of various RE nanomaterials, as well as the molecular mechanisms involved in these biological events. Further, we extend to discuss the challenges and prospects of RE smart nano-biomaterials in the field of bone tissue engineering and implantology.

Surface charge-dependent mitochondrial response to similar intracellular nanoparticle contents at sublethal dosages

Background

Considering the inevitability for humans to be frequently exposed to nanoparticles (NPs), understanding the biosafety of NPs is important for rational usage. As an important part of the innate immune system, macrophages are widely distributed in vital tissues and are also a dominant cell type that engulfs particles. Mitochondria are one of the most sensitive organelles when macrophages are exposed to NPs. However, previous studies have mainly reported the mitochondrial response upon high-dose NP treatment. Herein, with gold nanoparticles (AuNPs) as a model, we investigated the mitochondrial alterations induced by NPs at a sublethal concentration.

Results

At a similar internal exposure dose, different AuNPs showed distinct degrees of effects on mitochondrial alterations, including reduced tubular mitochondria, damaged mitochondria, increased reactive oxygen species, and decreased adenosine triphosphate. Cluster analysis, two-way ANOVA, and multiple linear regression suggested that the surface properties of AuNPs were the dominant determinants of the mitochondrial response. Based on the correlation analysis, the mitochondrial response was increased with the change in zeta potential from negative to positive. The alterations in mitochondrial respiratory chain proteins indicated that complex V was an indicator of the mitochondrial response to low-dose NPs.

Conclusion

Our current study suggests potential hazards of modified AuNPs on mitochondria even under sublethal dose, indicates the possibility of surface modification in biocompatibility improvement, and provides a new way to better evaluation of nanomaterials biosafety.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00429-8.

Carbon dots from roasted chicken accumulate in lysosomes and induce lysosome-dependent cell death

Thermal processing may generate toxicants. Carbon dots (CDs) from baked foods are toxic to cells; however, their molecular mechanism is still unexplored to date. The present study investigated the effects of CDs from roasted chicken breasts on normal rat kidney (NRK) and Caco-2 cells. The average size of CDs heated at 200 °C and 300 °C was about 2.8 nm and 1.2 nm, respectively. The element and surface groups of CDs were analyzed via X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), respectively. It was confirmed that the CDs were internalized in lysosomes and induced apoptosis. Furthermore, Z-VAD-FMK did not decrease the rate of apoptosis. The acquired data further confirmed that these internalized CDs enlarged lysosomes, decreased the lysosomal enzyme degradation activity and increased the lysosomal pH value. An increase in the co-localization of RIPK3 in lysosomes in the CD-treated groups was observed. The CD treatment increased the protein level of receptor interaction protein 1 (RIPK1) and receptor interaction protein 3 (RIPK3). Overall, CDs from the baked chicken breast induced lysosomal membrane permeabilization and initiated lysosome-dependent cell death and necroptosis. Our results elucidated the toxic mechanism of CDs from baked chicken breast and implied that food thermal processing at a lower temperature is beneficial to human health.

Recent progress on nanomedicine-induced ferroptosis for cancer therapy

The current treatment strategies for cancer therapy have posed many problems in achieving high efficacy. Therefore, an urgent step is needed to develop innovative therapies that can win beyond satisfactory results against tumor. Ferroptosis that is a kind of non-apoptotic based programmed cell death has played a crucial role in eradicating tumors by reactive oxygen species and iron-dependent pathways. Research shows a remarkable potential of ferroptosis in eliminating aggressive malignancies resistant to traditional therapies. The combination of nanomedicine and ferroptosis has revealed a close relationship for the treatment of various cancer types with high efficacy. This review introduces the basics of nanomedicine-based ferroptosis first to emphasize the feasibility and properties of ferroptosis in cancer therapy. Then, the current research on the applications of nanomedicine for the ferroptosis-based anticancer therapy is highlighted. Finally, conclusions and future research directions in perspective of various challenges in developing nanomedicine-based ferroptosis into clinical therapeutics are discussed.

Cell and molecular toxicity of lanthanum nanoparticles: are there possible risks to humans?

Lanthanum nanoparticles are widely used in industry, agriculture, and biomedicine. Over 900 kg of lanthanum is annually released into the environment only in Europe, 50 times higher than the metals, mercury, and cadmium's environmental spread. Human health risk associated with long-term exposure to the abundant lanthanum nanoparticles is a concerning environmental issue. Due to lanthanum's ability to disrupt the main biological barriers and interrupt various cells' hemostasis, they seem to cause severe disruptions to various tissues. This review opens a new perspective regarding the cellular and molecular interaction of nanosized and ionic lanthanum with the possible toxicity on the nervous system and other tissues that would show lanthanum nanoparticles' potential danger to follow in toxicological science.

Induced Autophagy of Macrophages and the Regulation of Inflammatory Effects by Perovskite Nanomaterial LaNiO3

Perovskite nanomaterials (NMs) possess excellent physicochemical properties and have promising applications in light-emitting diodes (LEDs), lasers, photodetectors, and artificial synapse electronics. Potential exposure to these NMs happens in the manufacture and application of the perovskite-based products, however, the biological safety of these NMs is still unknown. Here, we used the LaNiO₃ NM (LNO), a typical kind of perovskite nanostructures to study the interaction with macrophages (J774A.1) and to explore its biological effects at the cellular level. Firstly, we characterized the properties of LNO including the size, shape, and crystal structure using Transmission electronic microscope (TEM), Dynamic lighting scattering (DLS), and X-ray diffraction (XRD). Secondly, to gain a better understanding of the biological effect, we evaluated the effect of LNO on cell viability and found that LNO induced cell autophagy at a concentration of 5 μg/ml and influenced the inflammatory response based on RT-PCR result. Finally, we demonstrated the mechanism that LNO causes cell autophagy and immune response is probably due to the metal ions released from LNO in acidic lysosomes, which triggered ROS and increased lysosomal membrane permeation. This study indicates the safety aspect of perovskite NMs and may guide the rational design of perovskite NMs with more biocompatibility during their manufacture and application.

Atmospheric particulate matter impedes autophagic flux by impairing lysosomal milieu and integrity in human umbilical vein endothelial cells (HUVECs)

Autophagy is a dynamic process for waste disposal and cell equilibrium. Previous studies have demonstrated that atmospheric particulate matter (APM) induces autophagy and enhances LC3II expression in human vascular endothelial cells. However, the underlying mechanism of autophagosome accumulation in human vascular endothelial cells under the exposure to APM has not been understood. In principle, the upregulation of LC3II or autophagosomes accumulation is presumably caused by the enhancement of autophagic ability, or alternatively, by the abnormal autophagic degradation. Therefore, in the current study, autophagic ability and autophagic flux are systemically studied to decipher the exact cause of autophagosomes accumulation in human umbilical vein endothelial cells (HUVECs) in response to a standard urban particulate matter, PM SRM1648a. As a result, it was observed that after 24 h of exposure, PM SRM1648a significantly increases LC3II expression with apparent autophagosomes accumulation in HUVECs. Compared with the control group, there is a time-dependent increase in p62, a protein of autophagic substrate that can be preliminarily used to evaluate the autophagic degradation, in the PM SRM1648a-exposed HUVECs, which suggested that normal function of autophagic degradation was probably impaired. Additionally, mRFP-GFP-LC3 assay and LAMP-2/LC3B co-localization suggested that autolysosomes (fusion between autophagosomes and lysosomes) were partially inhibited in PM SRM1648a-treated HUVECs. Furthermore, LC3II turn-over assay hinted that after 24 h, LC3II upregulation is attributed to the blockage of autophagic flux instead of the enhancement of autophagic induction. Mechanistically, the blockade of autophagic flux can be explained by the detrimental effects of PM SRM1648a on lysosomal function, including lysosomal destabilization, lysosomal alkalization and hydrolase inactivation, which are involved in the blockade of fusion between autophagosomes and lysosomes, further disrupting autophagic degradation and waste disposal. These observations provide evidence that PM SRM1648a destroys the equilibrium of lysosomal stability and thus results in the dysfunction of autophagic flux, eventually contributing to endothelial cell damage.

Silver Nanoparticles Induced Oxidative Stress and Mitochondrial Injuries Mediated Autophagy in HC11 Cells Through Akt/AMPK/mTOR Pathway

Silver nanoparticles (AgNPs) are widely used in industrial products, and they have good antibacterial properties, with potential for prevention and treatment of cow mastitis. However, concerns exist about the cytotoxicity of AgNPs. Thus, we have studied the role of autophagy in AgNP-induced cytotoxicity in mouse HC11 mammary epithelium cells. We found that AgNPs injured HC11 cells, with release of lactate dehydrogenase (LDH). AgNPs also induced autophagy in HC11 cells, which was associated with oxidative stress, as indicated by increased reactive oxygen species (ROS) and increased expression of hemoxygenase-1(HO-1) and Nrf2. Mitochondria were altered by AgNPs: mitochondrial membrane potential (MMP) was decreased and the expression of PINK1 and Parkin was increased. AgNPs also increased the expression of p-AMPK and decreased the expression of p-Akt and p-mTOR. The addition of 3-methyl adenine inhibited autophagy and enhanced the cytotoxicity of AgNPs, indicating that autophagy is protective against AgNP-induced cell death. In summary, AgNPs induced protective autophagy in HC11 cells via the Akt/AMPK/mTOR pathway, associated with cellular oxidative stress and mitochondrial alterations. Our research confirms that AgNPs may damage the breast tissue in clinical applications and should be used with caution. Further research is necessary to clarify whether the damage caused by AgNPs will affect the lactation function of the mammary glands and possible residues in milk.

Combination effect of nanoparticles on the acute pulmonary inflammogenic potential: additive effect and antagonistic effect

The combination effect of co-exposed different types of nanomaterials is little known although humans are generally exposed to a mixture of nanomaterials from urban ultrafine particles or industrial nanomaterials. Herein, we evaluated the combined effect of nanoparticles (NPs) using three types of NPs in different inflammogenic categories: carbon black (CB), nickel oxide (NiO), and copper oxide (CuO). A single type of NPs or NPs in combination was intratracheally instilled into the lungs of rats and the bronchoalveolar lavage fluid (BALF) was analyzed at 24 h after instillation to evaluate the acute inflammogenic potential. The percentage of neutrophils in BALF was selected as a toxicity endpoint and the potential for reactive oxygen species (ROS) generation, dose-response of the combined effect, sequential treatment of CB and NiO, and uptake of NiO to alveolar macrophages after combined treatment of CB and NiO were evaluated for the mechanism of the combined effect. Co-exposure of CuO and NiO showed an additive effect on the percentage of neutrophils and ROS generation potential, which implies that the physicochemical properties of each NP are not influenced by the other type. While CB exerted an antagonistic effect on the percentage of neutrophils in combined treatment with CuO or NiO. The antagonistic effect of CB was due to the scavenging activity of the ROS generated by the CuO and NiO rather than the competition in cellular uptake to target cells (i.e. alveolar macrophages), which highlight the importance of the combined effect of NPs in the risk assessment.

Nanoparticle-induced ferroptosis: detection methods, mechanisms and applications

Although ferroptosis is an iron-dependent cell death mechanism involved in the development of some severe diseases (e.g., Parkinsonian syndrome, stroke and tumours), the combination of nanotechnology with ferroptosis for the treatment of these diseases has attracted substantial research interest. However, it is challenging to differentiate nanoparticle-induced ferroptosis from other types of cell deaths (e.g., apoptosis, pyroptosis, and necrosis), elucidate the detailed mechanisms and identify the key property of nanoparticles responsible for ferroptotic cell deaths. Therefore, a summary of these aspects from current research on nano-ferroptosis is important and timely. In this review, we endeavour to summarize some convincing techniques that can be employed to specifically examine ferroptotic cell deaths. Then, we discuss the molecular initiating events of nanosized ferroptosis inducers and the cascade signals in cells, and therefore elaborate the ferroptosis mechanisms. Besides, the key physicochemical properties of nano-inducers are also discussed to acquire a fundamental understanding of nano-structure-activity relationships (nano-SARs) involved in ferroptosis, which may facilitate the design of nanomaterials to deliberately tune ferroptosis. Finally, future perspectives on the fundamental understanding of nanoparticle-induced ferroptosis and its applications are provided.

LncRNA loc105377478 promotes NPs-Nd2O3-induced inflammation in human bronchial epithelial cells through the ADIPOR1/NF-κB axis

With the wide application of neodymium oxide nanoparticles (NPs-Nd₂O₃) in various fields, their health hazards have aroused public concern in recent years. However, data regarding the cytotoxicity of NPs-Nd₂O₃ is limited. In this study, we investigated the function and mechanism of long-chain non-coding RNAs (lncRNAs) in NPs-Nd₂O₃-induced airway inflammation. Treatment with NPs-Nd₂O₃ induced an inflammatory response in human bronchial epithelial cells (16HBE) by upregulating the expression of interleukin-6 (IL-6) and interleukin-8 (IL-8). The levels of LDH and intracellular ROS in the cells treated by various doses of NPs-Nd₂O₃ also increased significantly. After treatment with 10 μg/ml NPs-Nd₂O₃, RNA microarray and real-time quantitative polymerase chain reaction (qRT-PCR) showed a significant upregulation of lncRNA loc105377478. Functional experiments suggested lncRNA loc105377478 enhanced the expression of IL-6, IL-8 and ROS in NPs-Nd₂O₃-treated 16HBE cells, and it was further demonstrated that lncRNA loc105377478 promoted the activation of NF-κB by negatively regulating ADIPOR1 expression. Moreover, the expression of IL-6 and IL-8 in NPs-Nd₂O₃-treated 16HBE cells was regulated by lncRNA loc105377478, which was mediated by the NF-κB signaling pathway. In conclusion, lncRNA loc105377478 promotes NF-κB activation by negatively regulating ADIPOR1 expression, thereby upregulating the expression of IL-6 and IL-8 in 16HBE cells treated with NPs-Nd₂O₃.

Cytotoxic lanthanum oxide nanoparticles sensitize glioblastoma cells to radiation therapy and temozolomide: an in vitro rationale for translational studies

Glioblastoma (GBM) is a malignant brain tumour with a dismal prognosis, despite best treatment by surgical resection, radiation therapy (RT) and chemotherapy with temozolomide (TMZ). Nanoparticle (NP) therapy is an emerging consideration due to the ability of NPs to be formulated and cross the blood brain barrier. Lanthanum oxide (La2O3) NPs are therapeutically advantageous due to the unique chemical properties of lanthanum making it cytotoxic to cancers, and able to enhance existing anti-cancer treatments. However, La2O3 NPs have yet to be thoroughly investigated in brain tumors. We show that these NPs can reach the brain after venous injection, penetrate into GBM cells via endocytosis, dissociate to be cytotoxic, and enhance the therapeutic effects of RT and TMZ. The mechanisms of cell death by La2O3 NPs were found to be multifaceted. Increasing NP concentration was correlated to increased intrinsic and extrinsic apoptosis pathway markers in a radical oxygen species (ROS)-dependent manner, as well as involving direct DNA damage and autophagic pathways within GBM patient-derived cell lines. NP interactions to sensitize GBM to RT and TMZ were shown to involve these pathways by enhancing ROS and apoptotic mechanisms. We therefore demonstrate the therapeutic potential of La2O3 NPs to treat GBM cells in vitro, and encourage translational exploration in the future.

The role of lysosome in regulated necrosis

Lysosome is a ubiquitous acidic organelle fundamental for the turnover of unwanted cellular molecules, particles, and organelles. Currently, the pivotal role of lysosome in regulating cell death is drawing great attention. Over the past decades, we largely focused on how lysosome influences apoptosis and autophagic cell death. However, extensive studies showed that lysosome is also prerequisite for the execution of regulated necrosis (RN). Different types of RN have been uncovered, among which, necroptosis, ferroptosis, and pyroptosis are under the most intensive investigation. It becomes a hot topic nowadays to target RN as a therapeutic intervention, since it is important in many patho/physiological settings and contributing to numerous diseases. It is promising to target lysosome to control the occurrence of RN thus altering the outcomes of diseases. Therefore, we aim to give an introduction about the common factors influencing lysosomal stability and then summarize the current knowledge on the role of lysosome in the execution of RN, especially in that of necroptosis, ferroptosis, and pyroptosis.

Zinc oxide nanoparticles effectively regulate autophagic cell death by activating autophagosome formation and interfering with their maturation

BACKGROUND

With the development of zinc oxide nanoparticles (ZnO NPs) in the field of nanotechnology, their toxicological effects are attracting increasing attention, and the mechanisms for ZnO NPs neurotoxicity remain obscure. In an attempt to address concerns regarding neurotoxicity of ZnO NPs, we explored the relationship between free zinc ions, reactive oxygen species (ROS) and neurotoxic mechanisms in ZnO NPs-exposed PC12 cells.

RESULT

This study demonstrated the requirement of free zinc ions shed by ZnO NPs to over generation of intracellular ROS. Next, we identified autophagic cell death was the major mode of cell death induced by ZnO NPs, and autophagosome accumulation resulted from not only induction of autophagy, but also blockade of autophagy flux. We concluded that autophagic cell death, resulting from zinc ions-ROS-c-Jun N-terminal kinase (JNK)-autophagy positive feedback loop and blockade of autophagosomal-lysosomal fusion, played a major role in the neurotoxicity of ZnO NPs.

CONCLUSION

Our study contributes to a better understanding of the neurotoxicity of ZnO NPs and might be useful for designing and developing new biosafety nanoparticles in the future.

Molecular Mechanisms, Characterization Methods, and Utilities of Nanoparticle Biotransformation in Nanosafety Assessments

It is a big challenge to reveal the intrinsic cause of a nanotoxic effect due to diverse branches of signaling pathways induced by engineered nanomaterials (ENMs). Biotransformation of toxic ENMs involving biochemical reactions between nanoparticles (NPs) and biological systems has recently attracted substantial attention as it is regarded as the upstream signal in nanotoxicology pathways, the molecular initiating event (MIE). Considering that different exposure routes of ENMs may lead to different interfaces for the arising of biotransformation, this work summarizes the nano-bio interfaces and dose calculation in inhalation, dermal, ingestion, and injection exposures to humans. Then, five types of biotransformation are shown, including aggregation and agglomeration, corona formation, decomposition, recrystallization, and redox reactions. Besides, the characterization methods for investigation of biotransformation as well as the safe design of ENMs to improve the sustainable development of nanotechnology are also discussed. Finally, future perspectives on the implications of biotransformation in clinical translation of nanomedicine and commercialization of nanoproducts are provided.

Safety Considerations of Cancer Nanomedicine-A Key Step toward Translation

The rate of translational effort of nanomedicine requires strategic planning of nanosafety research in order to enable clinical trials and safe use of nanomedicine in patients. Herein, the experiences that have emerged based on the safety data of classic liposomal formulations in the space of oncology are discussed, along with a description of the new challenges that need to be addressed according to the rapid expansion of nanomedicine platform beyond liposomes. It is valuable to consider the combined use of predictive toxicological assessment supported by deliberate investigation on aspects such as absorption, distribution, metabolism, and excretion (ADME) and toxicokinetic profiles, the risk that may be introduced during nanomanufacture, unique nanomaterials properties, and nonobvious nanosafety endpoints, for example. These efforts will allow the generation of investigational new drug-enabling safety data that can be incorporated into a rational infrastructure for regulatory decision-making. Since the safety assessment relates to nanomaterials, the investigation should cover the important physicochemical properties of the material that may lead to hazards when the nanomedicine product is utilized in humans.

Gadolinium Oxide Nanoparticles Induce Toxicity in Human Endothelial HUVECs via Lipid Peroxidation, Mitochondrial Dysfunction and Autophagy Modulation

In spite of the potential preclinical advantage of Gd₂O₃ nanoparticles (designated here as GO NPs) over gadolinium-based compounds in MRI, recent concerns of gadolinium deposits in various tissues undergoing MRI demands a mechanistic investigation. Hence, we chose human to measure umbilical vein endothelial cells (HUVECs) that line the vasculature and relevant biomarkers due to GO NPs exposure in parallel with the NPs of ZnO as a positive control of toxicity. GO NPs, as measured by TEM, had an average length of 54.8 ± 29 nm and a diameter of 13.7 ± 6 nm suggesting a fiber-like appearance. With not as pronounced toxicity associated with a 24-h exposure, GO NPs induced a concentration-dependent cytotoxicity (IC₅₀ = 304 ± 17 µg/mL) in HUVECs when exposed for 48 h. GO NPs emerged as significant inducer of lipid peroxidation (LPO), reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and autophagic vesicles in comparison to that caused by ZnO NPs at its IC₅₀ for the same exposure time (48 h). While ZnO NPs clearly appeared to induce apoptosis, GO NPs revealed both apoptotic as well as necrotic potentials in HUVECs. Intriguingly, the exogenous antioxidant NAC (N-acetylcysteine) co-treatment significantly attenuated the oxidative imbalance due to NPs preventing cytotoxicity significantly.

Pyrogenic and Precipitated Amorphous Silica Nanoparticles Differentially Affect Cell Responses to LPS in Human Macrophages

Previous work has demonstrated that precipitated (NM-200) and pyrogenic (NM-203) Amorphous Silica Nanoparticles (ASNPs) elicit the inflammatory activation of murine macrophages, with more pronounced effects observed with NM-203. Here, we compare the effects of low doses of NM-200 and NM-203 on human macrophage-like THP-1 cells, assessing how the pre-exposure to these nanomaterials affects the cell response to lipopolysaccharide (LPS). Cell viability was affected by NM-203, but not by NM-200, and only in the presence of LPS. While NM-203 stimulated mTORC1, neither ASNPs activated NFκB or the transcription of its target genes PTGS2 and IL1B. NM-200 and NM-203 caused a block of the autophagic flux and inhibited the LPS-dependent increase of Glutamine Synthetase (GS) expression. Both ASNPs suppressed the activation of caspase-1, delaying the LPS-dependent secretion of IL-1β. Thus, ASNPs modulate several important pathways in human macrophages, altering their response to LPS. NM-203 had larger effects on autophagy, mTORC1 activity and GS expression than NM-200, confirming the higher biological activity of pyrogenic ASNPs when compared with precipitated ASNPs.

Vacancies on 2D transition metal dichalcogenides elicit ferroptotic cell death

Sustainable developments of nanotechnology necessitate the exploration of structure-activity relationships (SARs) at nano-bio interfaces. While ferroptosis may contribute in the developments of some severe diseases (e.g., Parkinson's disease, stroke and tumors), the cellular pathways and nano-SARs are rarely explored in diseases elicited by nano-sized ferroptosis inducers. Here we find that WS2 and MoS2 nanosheets induce an iron-dependent cell death, ferroptosis in epithelial (BEAS-2B) and macrophage (THP-1) cells, evidenced by the suppression of glutathione peroxidase 4 (GPX4), oxygen radical generation and lipid peroxidation. Notably, nano-SAR analysis of 20 transition metal dichalcogenides (TMDs) disclosures the decisive role of surface vacancy in ferroptosis. We therefore develop methanol and sulfide passivation as safe design approaches for TMD nanosheets. These findings are validated in animal lungs by oropharyngeal aspiration of TMD nanosheets. Overall, our study highlights the key cellular events as well as nano-SARs in TMD-induced ferroptosis, which may facilitate the safe design of nanoproducts.

Silica nanoparticles induce lung inflammation in mice via ROS/PARP/TRPM2 signaling-mediated lysosome impairment and autophagy dysfunction

Background

Wide applications of nanoparticles (NPs) have raised increasing concerns about safety to humans. Oxidative stress and inflammation are extensively investigated as mechanisms for NPs-induced toxicity. Autophagy and lysosomal dysfunction are emerging molecular mechanisms. Inhalation is one of the main pathways of exposing humans to NPs, which has been reported to induce severe pulmonary inflammation. However, the underlying mechanisms and, more specifically, the interplays of above-mentioned mechanisms in NPs-induced pulmonary inflammation are still largely obscure. Considered that NPs exposure in modern society is often unavoidable, it is highly desirable to develop effective strategies that could help to prevent nanomaterials-induced pulmonary inflammation.

Results

Pulmonary inflammation induced by intratracheal instillation of silica nanoparticles (SiNPs) in C57BL/6 mice was prevented by PJ34, a poly (ADP-ribose) polymerase (PARP) inhibitor. In human lung bronchial epithelial (BEAS-2B) cells, exposure to SiNPs reduced cell viability, and induced ROS generation, impairment in lysosome function and autophagic flux. Inhibition of ROS generation, PARP and TRPM2 channel suppressed SiNPs-induced lysosome impairment and autophagy dysfunction and consequent inflammatory responses. Consistently, SiNPs-induced pulmonary inflammation was prevented in TRPM2 deficient mice.

Conclusion

The ROS/PARP/TRPM2 signaling is critical in SiNPs-induced pulmonary inflammation, providing novel mechanistic insights into NPs-induced lung injury. Our study identifies TRPM2 channel as a new target for the development of preventive and therapeutic strategies to mitigate nanomaterials-induced lung inflammation.

Graphical abstract

Quantitative Structure-Activity Relationship Models for Predicting Inflammatory Potential of Metal Oxide Nanoparticles

BACKGROUND

Although substantial concerns about the inflammatory effects of engineered nanomaterial (ENM) have been raised, experimentally assessing toxicity of various ENMs is challenging and time-consuming. Alternatively, quantitative structure-activity relationship (QSAR) models have been employed to assess nanosafety. However, no previous attempt has been made to predict the inflammatory potential of ENMs.

OBJECTIVES

By employing metal oxide nanoparticles (MeONPs) as a model ENM, we aimed to develop QSAR models for prediction of the inflammatory potential by their physicochemical properties.

METHODS

We built a comprehensive data set of 30 MeONPs to screen a proinflammatory cytokine interleukin (IL)-1 beta (IL- 1 β ) release in THP-1 cell line. The in vitro hazard ranking was validated in mouse lungs by oropharyngeal instillation of six randomly selected MeONPs. We established QSAR models for prediction of MeONP-induced inflammatory potential via machine learning. The models were further validated against seven new MeONPs. Density functional theory (DFT) computations were exploited to decipher the key mechanisms driving inflammatory responses of MeONPs.

RESULTS

Seventeen out of 30 MeONPs induced excess IL- 1 β production in THP-1 cells. In vivo disease outcomes were highly relevant to the in vitro data. QSAR models were developed for inflammatory potential, with predictive accuracy (ACC) exceeding 90%. The models were further validated experimentally against seven independent MeONPs (ACC = 86 % ). DFT computations and experimental results further revealed the underlying mechanisms: MeONPs with metal electronegativity lower than 1.55 and positive ζ -potential were more likely to cause lysosomal damage and inflammation.

CONCLUSIONS

IL- 1 β released in THP-1 cells can be an index to rank the inflammatory potential of MeONPs. QSAR models based on IL- 1 β were able to predict the inflammatory potential of MeONPs. Our approach overcame the challenge of time- and labor-consuming biological experiments and allowed for computational assessment of MeONP inflammatory potential by characterization of their physicochemical properties. https://doi.org/10.1289/EHP6508.