Pulmonary toxicity and gene expression changes after short-term inhalation exposure to surface-modified copper oxide nanoparticles

Chitosan-Based Nanocapsules as a Delivery System of Hydrophobic Carnosic Acid, A Model Neuroprotective Drug

Introduction

Since the population of Europe is rapidly aging, the number of cases of neurodegenerative diseases sharply increases. One of the most significant limitations of current neurodegenerative disease treatment is the inefficient delivery of neuroprotective drugs to the affected part of the brain. One of the promising methods to improve the pharmacokinetic and pharmacodynamic properties of antioxidants is their encapsulation in nanocarriers.

Materials and Methods

Encapsulation of carnosic acid into a chitosan-based nanoparticle system with ultrasound-assisted emulsification process was developed. The physicochemical properties (size, stability, concentration of nanoparticles) of obtained nanocapsules were analyzed. Also, the cytotoxicity and neuroprotective effect in SH-SY5Y cells exposed to toxic concentration of H2O2 of the obtained nanoparticles were evaluated in vitro.

Results and Discussion

The capsules with diameters between 90 and 150 nm and long-term stability were obtained. Cytotoxicity tests of empty capsules indicate that observed toxic effects were concentration dependent and lower concentrations (dilution above 500×) can be considered as safe for tested cells. Our study also indicates that encapsulation of carnosic acid decreased the cytotoxicity of empty nanocapsules and can efficiently protect SH-SY5Y cells from factors causing cell destruction. In addition, the neuroprotective efficacy of carnosic acid loaded nanocapsules was also demonstrated in SH-SY5Y cells exposed to toxic concentration of H2O2. The designed nanoparticles appear to possess sufficient biocompatibility to deserve their further evaluation in in vivo models.

Copper oxide nanoparticles exacerbate chronic obstructive pulmonary disease by activating the TXNIP-NLRP3 signaling pathway

BACKGROUND

Although copper oxide nanoparticles (CuONPs) offer certain benefits to humans, they can be toxic to organs and exacerbate underlying diseases upon exposure. Chronic obstructive pulmonary disease (COPD), induced by smoking, can worsen with exposure to various harmful particles. However, the specific impact of CuONPs on COPD and the underlying mechanisms remain unknown. In this study, we investigated the toxic effects of CuONPs on the respiratory tract, the pathophysiology of CuONPs exposure-induced COPD, and the mechanism of CuONPs toxicity, focusing on thioredoxin-interacting protein (TXNIP) signaling using a cigarette smoke condensate (CSC)-induced COPD model.

RESULTS

In the toxicity study, CuONPs exposure induced an inflammatory response in the respiratory tract, including inflammatory cell infiltration, cytokine production, and mucus secretion, which were accompanied by increased TXNIP, NOD-like receptor protein 3 (NLRP3), caspase-1, and interleukin (IL)-1β. In the COPD model, CuONPs exposure induced the elevation of various indexes related to COPD, as well as increased TXNIP expression. Additionally, TNXIP-knockout (KO) mice showed a significantly decreased expression of NLRP3, caspase-1, and IL-1β and inflammatory responses in CuONPs-exposed COPD mice. These results were consistent with the results of an in vitro experiment using H292 cells. By contrast, TNXIP-overexpressed mice had a markedly increased expression of NLRP3, caspase-1, and IL-1β and inflammatory responses in CuONPs-exposed COPD mice.

CONCLUSIONS

We elucidated the exacerbating effect of CuONPs exposure on the respiratory tract with underlying COPD, as well as related signaling transduction via TXNIP regulation. CuONPs exposure significantly increased inflammatory responses in the respiratory tract, which was correlated with elevated TXNIP-NLRP3 signaling.

Copper Oxide Nanoparticles Induce Pulmonary Inflammation and Exacerbate Asthma via the TXNIP Signaling Pathway

Copper oxide nanoparticles (CuO NPs) have seen increasing use across various industries, raising significant concerns about their potential toxicity and the exacerbation of pre-existing conditions like asthma. Asthma, a chronic inflammatory condition of the airways, can be triggered or worsened by environmental factors such as allergens, air pollutants, and chemicals, including nanoparticles. This study aimed to investigate the pulmonary toxicity induced by CuO NPs and their impact on asthma, with a particular focus on the role of thioredoxin-interacting protein (TXNIP). Using an ovalbumin (OVA)-induced asthma model, we found that CuO NP exposure led to significant increases in inflammatory cell infiltration, cytokine production, airway hyperresponsiveness, OVA-specific immunoglobulin (Ig)E levels, and mucus production. These pathological changes were closely associated with the upregulation of TXNIP-related signaling pathways, including phosphorylated apoptosis signal-regulating kinase (p-ASK)1, the Bax/Bcl-2 ratio, and cleaved caspase-3 activation. Complementary in vitro experiments using NCI-H292 respiratory epithelial cells showed that CuO NP treatment enhanced TXNIP signaling and increased mRNA expression and the production of inflammatory cytokines. Notably, TXNIP knockdown significantly attenuated these CuO NP-induced effects. In conclusion, our findings suggest that CuO NP exposure not only induces pulmonary toxicity but also exacerbates asthma, primarily through the activation of the TXNIP signaling pathway.

Modeling Absorption Dynamics of Differently Shaped Gold Glioblastoma and Colon Cells Based on Refractive Index Distribution in Holotomographic Imaging

Herein, it is demonstrated that the toxic effect of gold nanoparticles (Au NPs) on three different cancer cell lines (U-118 and LN-299 glioblastoma and HCT-116 colon) depends on their absorption dynamics by cells, related to the shapes of the NPs. This hypothesis is confirmed by showing that i) based on refractive index (RI) values, typical for cell components and gold nanoparticles, it is possible to show the absorption dynamics and accumulation locations of the latter ones inside and outside of the cells. Moreover, ii) the saturation of the accumulated Au NPs volume in the cells depends on the nanoparticle shape and is reached in the shortest time for star-shaped Au NPs (AuS NPs) and in the longest time for spherical Au NPs (AuSph NPs) and on the cancer cells, where the longest and the shortest saturation are noticed for HCT-116 and LN-229 cells, respectively. A physical model of Au NPs absorption dynamics is proposed, where the diameter and shape of the Au NPs are used as parameters. The obtained theoretical data are consistent with experimental data in 85-98%.

The potential of copper oxide nanoparticles in nanomedicine: A comprehensive review

Nanotechnology is a modern scientific discipline that uses nanoparticles of metals like copper, silver, gold, platinum, and zinc for various applications. Copper oxide nanoparticles (CuONPs) are effective in biomedical settings, such as killing bacteria, speeding up reactions, stopping cancer cells, and coating surfaces. These inorganic nanostructures have a longer shelf life than their organic counterparts and are chemically inert and thermally stable. However, commercial synthesis of NPs often involves harmful byproducts and hazardous chemicals. Green synthesis for CuONPs offers numerous benefits, including being clean, harmless, economical, and environmentally friendly. Using naturally occurring organisms like bacteria, yeast, fungi, algae, and plants can make CuONPs more environmentally friendly. CuONPs are expected to be used in nanomedicine due to their potent antimicrobial properties and disinfecting agents for infectious diseases. This comprehensive review looks to evaluate research articles published in the last ten years that investigate the antioxidant, anticancer, antibacterial, wound healing, dental application and catalytic properties of copper nanoparticles generated using biological processes. Utilising the scientific approach of large-scale data analytics. However, their toxic effects on vertebrates and invertebrates raise concerns about their use for diagnostic and therapeutic purposes. Therefore, biocompatibility and non-toxicity are crucial for selecting nanoparticles for clinical research.

Bioinformatics and machine learning to support nanomaterial grouping

Nanomaterials (NMs) offer plenty of novel functionalities. Moreover, their physicochemical properties can be fine-tuned to meet the needs of specific applications, leading to virtually unlimited numbers of NM variants. Hence, efficient hazard and risk assessment strategies building on New Approach Methodologies (NAMs) become indispensable. Indeed, the design, the development and implementation of NAMs has been a major topic in a substantial number of research projects. One of the promising strategies that can help to deal with the high number of NMs variants is grouping and read-across. Based on demonstrated structural and physicochemical similarity, NMs can be grouped and assessed together. Within an established NM group, read-across may be performed to fill in data gaps for data-poor variants using existing data for NMs within the group. Establishing a group requires a sound justification, usually based on a grouping hypothesis that links specific physicochemical properties to well-defined hazard endpoints. However, for NMs these interrelationships are only beginning to be understood. The aim of this review is to demonstrate the power of bioinformatics with a specific focus on Machine Learning (ML) approaches to unravel the NM Modes-of-Action (MoA) and identify the properties that are relevant to specific hazards, in support of grouping strategies. This review emphasizes the following messages: 1) ML supports identification of the most relevant properties contributing to specific hazards; 2) ML supports analysis of large omics datasets and identification of MoA patterns in support of hypothesis formulation in grouping approaches; 3) omics approaches are useful for shifting away from consideration of single endpoints towards a more mechanistic understanding across multiple endpoints gained from one experiment; and 4) approaches from other fields of Artificial Intelligence (AI) like Natural Language Processing or image analysis may support automated extraction and interlinkage of information related to NM toxicity. Here, existing ML models for predicting NM toxicity and for analyzing omics data in support of NM grouping are reviewed. Various challenges related to building robust models in the field of nanotoxicology exist and are also discussed.

Roles of Nrf2/HO-1 and ICAM-1 in the Protective Effect of Nano-Curcumin against Copper-Induced Lung Injury

Copper (Cu) is an essential trace element for maintaining normal homeostasis in living organisms. Yet, an elevated level of Cu beyond homeostatic capacity may lead to oxidative damage of cellular components in several organs, including the lungs. This work investigated the effects of curcumin (Curc) and nano-curcumin (nCurc) against Cu-induced lung injury, accenting the roles of oxidative stress, inflammation, and the nuclear factor erythroid 2-related factor/heme oxygenase-1 Nrf2/HO-1 pathway. Rats were challenged with 100 mg/kg of copper sulfate (CuSO4) while being treated with Curc or nCurc for 7 days. Cu-triggered lung oxidative stress detected as dysregulation of oxidative/antioxidant markers, a downregulation of Nrf-2/HO-1 signaling, and an increase in the inflammatory markers interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and intracellular adhesion molecule-1 (ICAM-1). Additionally, it decreased the expression of lung-specific proteins, surfactant protein-C (SP-C), and mucin-1 (MUC-1), induced apoptosis, and caused changes in lung histology. Curc and nCurc alleviated CuSO4-induced lung injury by suppressing oxidative damage and inflammation and activating Nrf-2/HO-1. They also prevented apoptosis and restored the normal expression of SP-C and MUC-1. We concluded that nCurc exhibited superior efficacy compared with Curc in mitigating CuSO4-induced lung injury. This was associated with reduced oxidative stress, inflammation, and apoptotic responses and increased Nrf2/HO-1 signaling and expression of SP-C and MUC-1.

Pulmonary Toxicity and Proteomic Analysis in Bronchoalveolar Lavage Fluids and Lungs of Rats Exposed to Copper Oxide Nanoparticles

Copper oxide nanoparticles (CuO NPs) were intratracheally instilled into lungs at concentrations of 0, 0.15, and 1.5 mg/kg bodyweight to 7-week-old Sprague-Dawley rats. The cytotoxicity, immunotoxicity, and oxidative stress were evaluated, followed by proteomic analysis of bronchoalveolar lavage fluid (BALF) and lungs of rats. The CuO NPs-exposed groups revealed dose-dependent increases in total cells, polymorphonuclear leukocytes, lactate dyhydrogenase, and total protein levels in BALF. Inflammatory cytokines, including macrophage inflammatory protein-2 and tumor necrosis factor-α, were increased in the CuO NPs-treated groups. The expression levels of catalase, glutathione peroxidase-1, and peroxiredoxin-2 were downregulated, whereas that of superoxide dismutase-2 was upregulated in the CuO NPs-exposed groups. Five heat shock proteins were downregulated in rats exposed to high concentrations of CuO NPs. In proteomic analysis, 17 proteins were upregulated or downregulated, and 6 proteins were validated via Western blot analysis. Significant upregulation of 3-hydroxy-3-methylglutaryl-CoA synthase and fidgetin-like 1 and downregulation of annexin II, HSP 47 and proteasome α1 occurred in the CuO NPs exposed groups. Taken together, this study provides additional insight into pulmonary cytotoxicity and immunotoxicity as well as oxidative stress in rats exposed to CuO NPs. Proteomic analysis revealed potential toxicological biomarkers of CuO NPs, which also reveals the toxicity mechanisms of CuO NPs.

Time course of pulmonary inflammation and trace element biodistribution during and after sub-acute inhalation exposure to copper oxide nanoparticles in a murine model

Background

It has been shown that copper oxide nanoparticles (CuO NPs) induce pulmonary toxicity after acute or sub-acute inhalation exposures. However, little is known about the biodistribution and elimination kinetics of inhaled CuO NPs from the respiratory tract. The purposes of this study were to observe the kinetics of pulmonary inflammation during and after CuO NP sub-acute inhalation exposure and to investigate copper (Cu) biodistribution and clearance rate from the exposure site and homeostasis of selected trace elements in secondary organs of BALB/c mice.

Results

Sub-acute inhalation exposure to CuO NPs led to pulmonary inflammation represented by increases in lactate dehydrogenase, total cell counts, neutrophils, macrophages, inflammatory cytokines, iron levels in bronchoalveolar lavage (BAL) fluid, and lung weight changes. Dosimetry analysis in lung tissues and BAL fluid showed Cu concentration increased steadily during exposure and gradually declined after exposure. Cu elimination from the lung showed first-order kinetics with a half-life of 6.5 days. Total Cu levels were significantly increased in whole blood and heart indicating that inhaled Cu could be translocated into the bloodstream and heart tissue, and potentially have adverse effects on the kidneys and spleen as there were significant changes in the weights of these organs; increase in the kidneys and decrease in the spleen. Furthermore, concentrations of selenium in kidneys and iron in spleen were decreased, pointing to disruption of trace element homeostasis.

Conclusions

Sub-acute inhalation exposure of CuO NPs induced pulmonary inflammation, which was correlated to Cu concentrations in the lungs and started to resolve once exposure ended. Dosimetry analysis showed that Cu in the lungs was translocated into the bloodstream and heart tissue. Secondary organs affected by CuO NPs exposure were kidneys and spleen as they showed the disruption of trace element homeostasis and organ weight changes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00480-z.

Copper oxide nanoparticles trigger macrophage cell death with misfolding of Cu/Zn superoxide dismutase 1 (SOD1)

Background

Copper oxide (CuO) nanoparticles (NPs) are known to trigger cytotoxicity in a variety of cell models, but the mechanism of cell death remains unknown. Here we addressed the mechanism of cytotoxicity in macrophages exposed to CuO NPs versus copper chloride (CuCl₂).

Methods

The mouse macrophage cell line RAW264.7 was used as an in vitro model. Particle uptake and the cellular dose of Cu were investigated by transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The deposition of Cu in lysosomes isolated from macrophages was also determined by ICP-MS. Cell viability (metabolic activity) was assessed using the Alamar Blue assay, and oxidative stress was monitored by a variety of methods including a luminescence-based assay for cellular glutathione (GSH), and flow cytometry-based detection of mitochondrial superoxide and mitochondrial membrane potential. Protein aggregation was determined by confocal microscopy using an aggresome-specific dye and protein misfolding was determined by circular dichroism (CD) spectroscopy. Lastly, proteasome activity was investigated using a fluorometric assay.

Results

We observed rapid cellular uptake of CuO NPs in macrophages with deposition in lysosomes. CuO NP-elicited cell death was characterized by mitochondrial swelling with signs of oxidative stress including the production of mitochondrial superoxide and cellular depletion of GSH. We also observed a dose-dependent accumulation of polyubiquitinated proteins and loss of proteasomal function in CuO NP-exposed cells, and we could demonstrate misfolding and mitochondrial translocation of superoxide dismutase 1 (SOD1), a Cu/Zn-dependent enzyme that plays a pivotal role in the defense against oxidative stress. The chelation of copper ions using tetrathiomolybdate (TTM) prevented cell death whereas inhibition of the cellular SOD1 chaperone aggravated toxicity. Moreover, CuO NP-triggered cell death was insensitive to the pan-caspase inhibitor, zVAD-fmk, and to wortmannin, an inhibitor of autophagy, implying that this was a non-apoptotic cell death. ZnO NPs, on the other hand, triggered autophagic cell death.

Conclusions

CuO NPs undergo dissolution in lysosomes leading to copper-dependent macrophage cell death characterized by protein misfolding and proteasomal insufficiency. Specifically, we present novel evidence for Cu-induced SOD1 misfolding which accords with the pronounced oxidative stress observed in CuO NP-exposed macrophages. These results are relevant for our understanding of the consequences of inadvertent human exposure to CuO NPs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00467-w.

Lung toxicity profile of inhaled copper-nickel welding fume in A/J mice

Objective: Stainless steel welding creates fumes rich in carcinogenic metals such as chromium (Cr). Welding consumables devoid of Cr are being produced in an attempt to limit worker exposures to toxic and carcinogenic metals. The study objective was to characterize a copper-nickel (Cu-Ni) fume generated using gas metal arc welding (GMAW) and determine the pulmonary deposition and toxicity of the fume in mice exposed by inhalation. Materials and Methods: Male A/J mice (6-8 weeks of age) were exposed to air or Cu-Ni welding fumes for 2 (low deposition) or 4 (high deposition) hours/day for 10 days. Mice were sacrificed, and bronchoalveolar lavage (BAL), macrophage function, and histopathological analyses were performed at different timepoints post-exposure to evaluate resolution. Results and Discussion: Characterization of the fume indicated that most of the particles were between 0.1 and 1 µm in diameter, with a mass median aerodynamic diameter of 0.43 µm. Metal content of the fume was Cu (∼76%) and Ni (∼12%). Post-exposure, BAL macrophages had a reduced ability to phagocytose E. coli, and lung cytotoxicity was evident and significant (>12%-19% fold change). Loss of body weight was also significant at the early timepoints. Lung inflammation, the predominant finding identified by histopathology, was observed as a subacute response early that progressively resolved by 28 days with only macrophage aggregates remaining late (84 days). Conclusions: Overall, there was high acute lung toxicity with a resolution of the response in mice which suggests that the Cu-Ni fume may not be ideal for reducing toxic and inflammatory lung effects.

Genotoxicity and Gene Expression in the Rat Lung Tissue following Instillation and Inhalation of Different Variants of Amorphous Silica Nanomaterials (aSiO2 NM)

Several reports on amorphous silica nanomaterial (aSiO2 NM) toxicity have been questioning their safety. Herein, we investigated the in vivo pulmonary toxicity of four variants of aSiO2 NM: SiO2_15_Unmod, SiO2_15_Amino, SiO2_7 and SiO2_40. We focused on alterations in lung DNA and protein integrity, and gene expression following single intratracheal instillation in rats. Additionally, a short-term inhalation study (STIS) was carried out for SiO2_7, using TiO2_NM105 as a benchmark NM. In the instillation study, a significant but slight increase in oxidative DNA damage in rats exposed to the highest instilled dose (0.36 mg/rat) of SiO2_15_Amino was observed in the recovery (R) group. Exposure to SiO2_7 or SiO2_40 markedly increased oxidative DNA lesions in rat lung cells of the exposure (E) group at every tested dose. This damage seems to be repaired, since no changes compared to controls were observed in the R groups. In STIS, a significant increase in DNA strand breaks of the lung cells exposed to 0.5 mg/m3 of SiO2_7 or 50 mg/m3 of TiO2_NM105 was observed in both groups. The detected gene expression changes suggest that oxidative stress and/or inflammation pathways are likely implicated in the induction of (oxidative) DNA damage. Overall, all tested aSiO2 NM were not associated with marked in vivo toxicity following instillation or STIS. The genotoxicity findings for SiO2_7 from instillation and STIS are concordant; however, changes in STIS animals were more permanent/difficult to revert.