Single-Walled Carbon Nanotubes Attenuate Cytotoxic and Oxidative Stress Response of Pb in Human Lung Epithelial (A549) Cells

Lung Toxicity and Molecular Mechanisms of Lead-Based Perovskite Nanoparticles in the Respiratory System

Lead-based perovskite nanoparticles (Pb-PNPs) have found extensive applications across diverse fields. However, because of poor stability and relatively strong water solubility, the potential toxicity of Pb-PNPs released into the environment during their manufacture, usage, and disposal has attracted significant attention. Inhalation is a primary route through which human exposure to Pb-PNPs occurs. Herein, the toxic effects and underlying molecular mechanisms of Pb-PNPs in the respiratory system are investigated. The in vitro cytotoxicity of CsPbBr3 nanoparticles in BEAS-2B cells is studied using multiple bioassays and electron microscopy. CsPbBr3 nanoparticles of different concentrations induce excessive oxidative stress and cell apoptosis. Furthermore, CsPbBr3 nanoparticles specifically recruit the TGF-β1, which subsequently induces epithelial-mesenchymal transition. In addition, the biodistribution and lung toxicity of representative CsPbBr3 nanoparticles in ICR mice are investigated following intranasal administration. These findings indicate that CsPbBr3 nanoparticles significantly induce pulmonary inflammation and epithelial-mesenchymal transition and can even lead to pulmonary fibrosis in mouse models. Above findings expose the adverse effects and molecular mechanisms of Pb-PNPs in the lung, which broadens the safety data of Pb-PNPs.

Biological and chemical contamination of illegal, uncontrolled refuse storage areas in Poland

This study focused on assessing the microbiological and chemical contamination of air, soil and leachate in uncontrolled refuse storage areas in central Poland. The research included an analysis of the number of microorganisms (culture method), endotoxin concentration (gas chromatography-mass spectrometry), heavy metals level (atomic absorption spectrometry), elemental characteristics (elemental analyser), cytotoxicity assessment against A-549 (human lung) and Caco-2 (human colon adenocarcinoma) cell lines (PrestoBlue™ test) and toxic compound identification (ultra-high-performance liquid chromatography-quadrupole time-of-flight ultrahigh-resolution mass spectrometry). Microbial contamination differed depending on the dump and the group of tested microorganisms. The number of bacteria was: 4.3 × 10² - 1.8 × 10³ CFU m^-3 (air); 1.1 × 10³ - 1.2 × 10⁶ CFU mL^-1 (leachate); 1.0 × 10⁶ - 3.9 × 10⁶ CFU g^-1 (soil). Respectively, for air and soil the number of fungi was: 2.2 × 10² - 4.6 × 10² CFU m^-3; 1.8 × 10² - 3.9 × 10³ CFU g^-1. Metal levels (Fe, Mn, Pb, Zn, Al, Hg, Cd, Cu, Cr) were higher than in the control sample; however, the average concentrations did not exceed the permissible standards. The cytotoxicity of soil and leachate samples depended on the dump, sample and cell line tested. The leachates were more cytotoxic than soil extracts. Compounds belonging to pesticides, surfactants and biocides, chemicals and/or polymer degradation products, medicinal drugs and insect repellents were found. The detection of potential pathogens in the air, soil and leachate, the presence of toxic compounds and the confirmation of the cytotoxic effect of leachate and soil on human cell lines justify the need for further research on the risks posed by illegal dumps. These studies should aim at developing a unified assessment method and a method to minimise the risk of contaminants spreading in the environment, including harmful biological agents.

Sequential exposures of single walled carbon nanotubes and heavy metal ions to macrophages induce different cytotoxicity

The probability of occupational exposure rises with the increasing production and biomedical application of carbon nanotubes (CNTs). Thus, the risk of co-exposure of nanomaterials with environmental pollutants is also increasing. Although many studies have focused on the combined toxicity of nanomaterials and pollutants, more attention has been paid to the toxicity of nanomaterials after adsorbing pollutants or the toxicity of nanomaterials and pollutants exposed simultaneously. Few studies have been conducted on the toxicity and toxicity mechanisms of nanomaterials and environmental pollutants following sequential exposure. In this study, we employed THP-1 cells to investigate how pristine single walled CNTs (p-SWCNTs) and oxidized single walled CNTs (SWCNT-COOHs) pretreatments at a non-lethal dose of 10 μg/mL affect cell responses to metal ions (i. e., Pb²⁺, Cu²⁺, and Cr(VI)). We found that p-SWCNTs caused more significant damage to cell membrane integrity than SWCNT-COOHs, which led to higher metallothionein (MT) levels and increased transport of metal ions into cells. Pretreatment of p-SWCNTs in cells significantly increased the cytotoxicity of Pb²⁺, Cu²⁺, and Cr(VI) by 2-4-fold, whereas SWCNT-COOHs pretreated cells showed no noteworthy changes in response to heavy metals, which were further confirmed by the cellular reactive oxygen species (ROS) assays. These findings indicate that understanding the effects of the exposure sequence of engineered nanomaterials and environmental pollutants on their toxicity provides an excellent complement to combined toxicity evaluation.

Impact of weathered multi-walled carbon nanotubes on the epithelial cells of the intestinal tract in the freshwater grazers Lymnaea stagnalis and Rhithrogena semicolorata

Freshwater grazers are suitable organisms to investigate the fate of environmental pollutants, such as weathered multi-walled carbon nanotubes (wMWCNTs). One key process is the uptake of ingested materials into digestive or absorptive cells. To address this, we investigated the localization of wMWCNTs in the intestinal tracts of the mud snail Lymnaea stagnalis (L. stagnalis) and the mayfly Rhithrogena semicolorata (R. semicolorata). In L. stagnalis, bundles of wMWCNTs could be detected in the midgut lumen, whereas only single wMWCNTs could be detected in the lumina of the digestive gland. Intracellular uptake of wMWCNTs was detected by transmission electron microscopy (TEM) but was restricted to the cells of the digestive gland. In larvae of R. semicolorata, irritations of the microvilli and damages in the apical parts of the epithelial gut cells were detected after feeding with 1 to 10 mg/L wMWCNTs. In both models, we detected fibrillar structures in close association with the epithelial cells that formed peritrophic membranes (PMs). The PM may cause a reduced transmission of wMWCNT bundles into the epithelium by forming a filter barrier and potentially protecting the cells from the wMWCNTs. As a result, the uptake of wMWCNTs into cells is rare in mud snails and may not occur at all in mayfly larvae. In addition, we monitor physiological markers such as levels of glycogen or triglycerides and the RNA/DNA ratio. This ratio was significantly affected in L. stagnalis after 24 days with 10 mg/L wMWCNTs, but not in R. semicolorata after 28 days and 10 mg/L wMWCNTs. However, significant effects on the energy status of R. semicolorata were analysed after 28 days of exposure to 1 mg/L wMWCNTs. Furthermore, we observed a significant reduction of phagosomes per enterocyte cell in mayfly larvae at a concentration of 10 mg/L wMWCNTs (p < 0.01).

Combined effect of single-walled carbon nanotubes and cadmium on human lung cancer cells

Co-exposure of widely used single-walled carbon nanotubes (SWCNTs) and ubiquitous cadmium (Cd) to humans through ambient air is unavoidable. Studies on joint toxicity of SWCNTs and Cd in human cells are scarce. We aimed to investigate the joint effects of SWCNTs and Cd in human lung epithelial (A549) cells. Results showed that SWCNTs were safe while Cd induce significant toxicity to A549 cells. Remarkably, Cd-induced cell viability reduction, lactate dehydrogenase leakage, cell cycle arrest, dysregulation of apoptotic gene (p53, bax, bcl-2, casp3, and casp9), and mitochondrial membrane potential depletion were significantly mitigated following SWCNTs co-exposure. Cd-induced intracellular level of reactive oxygen species, hydrogen peroxide, and lipid peroxidation were significantly attenuated by SWCNT co-exposure. Moreover, glutathione depletion and lower activity of antioxidant enzymes after Cd exposure were also effectively abrogated by co-exposure of SWCNTs. Inductively coupled plasma-mass spectrometry study indicated that higher adsorption of Cd on SCWNTs might decreased cellular uptake and the toxic potential of Cd in A549 cells. Our work warranted further research to explore the potential mechanism of joint effects of SWCNTs and Cd at in vivo levels.

Polish and New Zealand Propolis as Sources of Antioxidant Compounds Inhibit Glioblastoma (T98G, LN-18) Cell Lines and Astrocytoma Cells Derived from Patient

Gliomas, including glioblastoma multiforme and astrocytoma, are common brain cancers in adults. Propolis is a natural product containing many active ingredients. The aim of this study was to compare the chemical composition, total phenolic content and concentration of toxic elements as well as the anticancer potential of Polish (PPE) and New Zealand (Manuka—MPE) propolis extracts on diffuse astrocytoma derived from patient (DASC) and glioblastoma (T98G, LN-18) cell lines. The antioxidants such as flavonoids and chalcones (pinocembrin, pinobanksin, pinobanksin 3-acetate and chrysin) were the main components in both types of propolis. The content of arsenic (As) and lead (Pb) in MPE was higher than PPE. The anti-proliferative study showed strong activity of PPE and MPE propolis on DASC, T98G, and LN-18 cells by apoptosis induction, cell cycle arrest and attenuated migration. These findings suggest that despite their different geographic origins, Polish and New Zealand propolis are sources of antioxidant compounds and show similar activity and a promising anti-glioma potential in in vitro study. However, further in vivo studies are required in order to assess therapeutic potential of propolis.

In vitro toxicity of carbon nanotubes: a systematic review

Carbon nanotube (CNT) toxicity-related issues provoke many debates in the scientific community. The controversial and disputable data about toxicity doses, proposed hazard effects, and human health concerns significantly restrict CNT applications in biomedical studies, laboratory practices, and industry, creating a barrier for mankind in the way of understanding how exactly the material behaves in contact with living systems. Raising the toxicity question again, many research groups conclude low toxicity of the material and its potential safeness at some doses for contact with biological systems. To get new momentum for researchers working on the intersection of the biological field and nanomaterials, i.e., CNT materials, we systematically reviewed existing studies with in vitro toxicological data to propose exact doses that yield toxic effects, summarize studied cell types for a more thorough comparison, the impact of incubation time, and applied toxicity tests. Using several criteria and different scientific databases, we identified and analyzed nearly 200 original publications forming a "golden core" of the field to propose safe doses of the material based on a statistical analysis of retrieved data. We also differentiated the impact of various forms of CNTs: on a substrate and in the form of dispersion because in both cases, some studies demonstrated good biocompatibility of CNTs. We revealed that CNTs located on a substrate had negligible impact, i.e., 90% of studies report good viability and cell behavior similar to control, therefore CNTs could be considered as a prospective conductive substrate for cell cultivation. In the case of dispersions, our analysis revealed mean values of dose/incubation time to be 4-5 μg mL-1 h-1, which suggested the material to be a suitable candidate for further studies to get a more in-depth understanding of its properties in biointerfaces and offer CNTs as a promising platform for fundamental studies in targeted drug delivery, chemotherapy, tissue engineering, biosensing fields, etc. We hope that the present systematic review will shed light on the current knowledge about CNT toxicity, indicate "dark" spots and offer possible directions for the subsequent studies based on the demonstrated here tabulated and statistical data of doses, cell models, toxicity tests, viability, etc.

Lead acetate versus cadmium sulfate in the modulation of main physiological pathways controlling detrusor muscle contractility in rat

Heavy metals have a deleterious effect on lower urinary tract functions. Scant data has been reported about metals’ effect on altering detrusor muscle contractility. Rats were given lead acetate (3, 30 mg/kg), cadmium sulfate (0.1, 1 mg/kg) or ferrous sulfate-iron overload-(3, 30 mg/kg), in a subacute toxicity study (21 days, ip). In-vitro tension experiments were conducted using isolated rat detrusor muscle. Measurement of heavy metal concentrations in blood and tissue homogenates was performed, as well as histopathological examinations. Subacute toxicity induced by treatment with lead and cadmium was manifested as a decrease in EFS, ACh, and ATP-mediated contraction of isolated detrusor muscle. Iron overload only decreased E_MAX of EFS and ACh-mediated contraction. Lead (30 mg/kg) caused an upward shift in the dose response curve of isoprenaline-induced relaxation, with a significant decrease in E_MAX. Lead (30 mg/kg) or cadmium (1 mg/kg) inhibited adenosine (10⁻⁵ M)-induced relaxation. Comparisons to control tissues showed a selective accumulation of metals in the detrusor muscle. Histopathological examinations revealed edema and inflammation in the urinary bladder. Directly added lead (10 mM) inhibited detrusor muscle contraction in-vitro, and its effect was decreased in presence of atropine, and potentiated in presence of TEA, L-NAME, or MB. Cadmium's (0.1 mM) inhibitory effect was reduced in presence of nifedipine or trifluoperazine. In conclusion, lead, cadmium, or iron induce detrusor hypoactivity: The inhibitory effect of lead may be mediated by modulating muscarinic receptors but not the K⁺/NO/cGMP pathway, whereas cadmium inhibitory effect may be mediated by inhibiting the Ca²⁺/calmodulin pathway.

Combined effects of nanoparticles and other environmental contaminants on human health - an issue often overlooked

Air pollution is considered as a major public health issue worldwide. It consists of a complex mixture of pollutants including nanoparticles to which we are increasingly exposed to due to the dramatic development of the nanotechnologies and their incidental or intentional release in the environment. Consequently, some concerns have raised about the combined toxicity of air particulates and other air pollutants on human health. However, the interactions between the contaminants and their resulting combined toxicity are often overlooked. Indeed, the biological effects triggered by nanoparticles are usually assessed focusing on individual nanoparticles, while their interaction with co-contaminants can deeply impact, either positively or negatively, their biodistribution, fate in the organism and toxicological profile (additive, synergistic or antagonistic responses). This paper presents a bibliographic review on the combined toxicity of nanoparticles and co-pollutants and discusses the underlying mechanisms. It also highlights the scarcity of data in the current literature, arguing for an urgent need to take into account the mixture effects to be more representative of real-life conditions for a better and accurate human health risk assessment and management.