Cytoprotective effect of deferiprone against aluminum chloride-induced oxidative stress and apoptosis in lymphocytes

In vitro evaluation of the cytotoxic and genotoxic effects of Al and Mn in ambient concentrations detected in groundwater intended for human consumption

Environmental exposure to metals can induce cytotoxic and genotoxic effects in cells and affect the health of the exposed population. To investigate the effects of aluminum (Al) and manganese (Mn), we evaluated their cytogenotoxicity using peripheral blood mononuclear cells (PBMCs) exposed to these metals at previously quantified concentrations in groundwater intended for human consumption. The cell viability, membrane integrity, nuclear division index (NDI), oxidative stress, cell death, cell cycle, and DNA damage were analyzed in PBMCs exposed to Al (0.2, 0.6, and 0.8 mg/L) and Mn (0.1, 0.3, 1.0, and 1.5 for 48 h. We found that Al induced late apoptosis; decreased cell viability, NDI, membrane integrity; and increased DNA damage. However, no significant alterations in the early apoptosis, cell cycle, and reactive oxygen species levels were observed. In contrast, exposure to Mn altered all evaluated parameters related to cytogenotoxicity. Our data show that even concentrations allowed by the Brazilian legislation for Al and Mn in groundwater intended for human consumption cause cytotoxic and genotoxic effects in PBMCs. Therefore, in view of the results found, a comprehensive approach through in vivo investigations is needed to give robustness and validity to the results obtained, thus broadening the understanding of the impacts of metals on the health of environmentally exposed people.

Taurine and deferiprone against Al-linked apoptosis in rat hippocampus

BACKGROUND

Aluminium (Al) overload has toxic effects on multiple organ systems, especially the nervous system. Al accumulation in the brain, especially the hippocampus, is an important factor contributing to Alzheimer's disease (AD). Deferiprone (DFP), a metal chelator, is used as a potential treatment for AD. In this study, we investigated the combined effect of taurine and DFP on Al chelation and hippocampal apoptosis in Al-exposed rats, as well as the underlying mechanisms of these effects to explore a possible therapy for AD.

METHODS

Male Wistar rats were divided into seven groups: negative control group (administered saline), Al-exposure group (administered AlCl₃ and saline), and five experimental groups (administered AlCl₃ and taurine, varying doses of DFP, or taurine with varying doses of DFP). After 8 weeks of treatment, the rats were sacrificed, and the terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick end labelling (TUNEL) assay was used to detect hippocampal apoptotic cells. Real-time quantitative PCR was used to assess the expression of the Bcl2 and Bax genes, and a western blotting assay was used to evaluate BCL2, BAX, and cleaved caspase-3 levels.

RESULTS

Compared to the negative control group, the number of apoptotic cells in the hippocampus increased, Bcl2 expression significantly decreased, and BAX and cleaved caspase-3 levels increased in the Al-exposure group. The combination of taurine and DFP exerted a protective effect by inhibiting hippocampal cell apoptosis through the BCL2, BAX, and caspase-3 signalling pathways. Compared with the taurine-administered group, the group administered taurine with DFP showed a significantly increased Bcl2 and decreased Bax expression.

CONCLUSION

The combination of taurine and DFP is a potential candidate for the treatment of AD induced by Al exposure.

Deferoxamine ameliorated Al(mal)3-induced neuronal ferroptosis in adult rats by chelating brain iron to attenuate oxidative damage

Aluminum (Al), a neurotoxic element, can induce Alzheimer's disease-like (AD-like) changes by triggering neuronal death. Iron homeostasis disturbance has also been implicated in Alzheimer's disease (AD), and excess iron exacerbates oxidative damage and cognitive defects. Ferroptosis is a nonapoptotic form of cell death dependent upon intracellular iron. However, the involvement of neuronal death induced by aluminum maltolate (Al(mal)₃) in the pathogenesis of AD remains elusive. In this study, the results of three different behavioral experiments suggested that the learning and memory ability deteriorated and autonomous activity declined of these rats that exposed Al(mal)₃ were alleviated by deferoxamine (DFO). Transmission electron microscope observations showed that the membrane was ruptured, and the membrane density increased and ridge disappearance (the most prominent characteristic of ferroptosis) in the perinuclear and cytoplasmic compartments of the hippocampal neurons were perceived in the exposure group, while the DFO group and 18 μM/kg Al(mal)₃+DFO group were alleviated compared with 18 μM/kg Al(mal)₃. In addition, DFO prevented oxidative stress, such as increased glutathione (GSH) and decreased malondialdehyde (MDA) and reactive oxygen species (ROS), while the latter two indexes had the same changing tendency as the total iron of brain tissue. These data indicated that Al(mal)₃ could cause ferroptosis in Sprague-Dawley (SD) rat neurons, which was inhibited by DFO via reducing the content of iron and increasing the ability of cells to resist oxidative damage.

SnO2-Doped ZnO/Reduced Graphene Oxide Nanocomposites: Synthesis, Characterization, and Improved Anticancer Activity via Oxidative Stress Pathway

BACKGROUND

Therapeutic selectivity and drug resistance are critical issues in cancer therapy. Currently, zinc oxide nanoparticles (ZnO NPs) hold considerable promise to tackle this problem due to their tunable physicochemical properties. This work was designed to prepare SnO2-doped ZnO NPs/reduced graphene oxide nanocomposites (SnO2-ZnO/rGO NCs) with enhanced anticancer activity and better biocompatibility than those of pure ZnO NPs.

MATERIALS AND METHODS

Pure ZnO NPs, SnO2-doped ZnO (SnO2-ZnO) NPs, and SnO2-ZnO/rGO NCs were prepared via a facile hydrothermal method. Prepared samples were characterized by field emission transmission electron microscopy (FETEM), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), ultraviolet-visible (UV-VIS) spectrometer, and dynamic light scattering (DLS) techniques. Selectivity and anticancer activity of prepared samples were assessed in human breast cancer (MCF-7) and human normal breast epithelial (MCF10A) cells. Possible mechanisms of anticancer activity of prepared samples were explored through oxidative stress pathway.

RESULTS

XRD spectra of SnO2-ZnO/rGO NCs confirmed the formation of single-phase of hexagonal wurtzite ZnO. High resolution TEM and SEM mapping showed homogenous distribution of SnO2 and rGO in ZnO NPs with high quality lattice fringes without any distortion. Band gap energy of SnO2-ZnO/rGO NCs was lower compared to SnO2-ZnO NPs and pure ZnO NPs. The SnO2-ZnO/rGO NCs exhibited significantly higher anticancer activity against MCF-7 cancer cells than those of SnO2-ZnO NPs and ZnO NPs. The SnO2-ZnO/rGO NCs induced apoptotic response through the upregulation of caspase-3 gene and depletion of mitochondrial membrane potential. Mechanistic study indicated that SnO2-ZnO/rGO NCs kill cancer cells through oxidative stress pathway. Moreover, biocompatibility of SnO2-ZnO/rGO NCs was also higher against normal breast epithelial (MCF10A cells) in comparison to SnO2-ZnO NPs and ZnO NPs.

CONCLUSION

SnO2-ZnO/rGO NCs showed enhanced anticancer activity and better biocompatibility than SnO2-ZnO NPs and pure ZnO NPs. This work suggested a new approach to improve the selectivity and anticancer activity of ZnO NPs. Studies on antitumor activity of SnO2-ZnO/rGO NCs in animal models are further warranted.

Barium Titanate (BaTiO3) Nanoparticles Exert Cytotoxicity through Oxidative Stress in Human Lung Carcinoma (A549) Cells

Barium titanate (BaTiO3) nanoparticles (BT NPs) have shown exceptional characteristics such as high dielectric constant and suitable ferro-, piezo-, and pyro-electric properties. Thus, BT NPs have shown potential to be applied in various fields including electro-optical devices and biomedicine. However, very limited knowledge is available on the interaction of BT NPs with human cells. This work was planned to study the interaction of BT NPs with human lung carcinoma (A549) cells. Results showed that BT NPs decreased cell viability in a dose- and time-dependent manner. Depletion of mitochondrial membrane potential and induction of caspase-3 and -9 enzyme activity were also observed following BT NP exposure. BT NPs further induced oxidative stress indicated by induction of pro-oxidants (reactive oxygen species and hydrogen peroxide) and reduction of antioxidants (glutathione and several antioxidant enzymes). Moreover, BT NP-induced cytotoxicity and oxidative stress were effectively abrogated by N-acetyl-cysteine (an ROS scavenger), suggesting that BT NP-induced cytotoxicity was mediated through oxidative stress. Intriguingly, the underlying mechanism of cytotoxicity of BT NPs was similar to the mode of action of ZnO NPs. At the end, we found that BT NPs did not affect the non-cancerous human lung fibroblasts (IMR-90). Altogether, BT NPs selectively induced cytotoxicity in A549 cells via oxidative stress. This work warrants further research on selective cytotoxicity mechanisms of BT NPs in different types of cancer cells and their normal counterparts.

Reduced graphene oxide mitigates cadmium-induced cytotoxicity and oxidative stress in HepG2 cells

Numerous applications of reduced graphene oxide (RGO) and pervasive cadmium (Cd) have led concern about their co-exposure to the environment and human. We studied the combined effects of RGO and Cd in human liver (HepG2) cells. Initially, we found that RGO (up to 50 μg/ml) did not harm to HepG2 cells while Cd induced dose-dependent (1-10 μg/ml) cytotoxicity. Exciting observations were that a non-cytotoxic concentration of RGO (25 μg/ml) effectively mitigates the toxic effects of Cd (2 μg/ml) such as cell viability reduction, lactate dehydrogenase release, and irregular cell morphology. Cd-induced cell cycle arrest, induction of caspases (3 and 9) enzymes activity, and loss of mitochondrial membrane potential were also significantly alleviated by RGO co-exposure. Moreover, generation of pro-oxidants (reactive oxygen species and hydrogen peroxide levels) and depletion of antioxidants (glutathione level and superoxide dismutase activity) due to Cd exposure was effectively attenuated by RGO co-exposure. Mitigating effect of RGO could be due to strong adsorption of Cd on the large surface area of RGO sheets, which decrease the cellular uptake and bioavailability of Cd for HepG2 cells. This study warrants future research on potential mechanisms of mitigating effects of RGO against Cd-induced toxicity in animal models.

Cytotoxic effects in transformed and non-transformed human breast cell lines after exposure to silver nanoparticles in combination with selected aluminium compounds, parabens or phthalates

This study was undertaken to assess cytotoxic effects of selected aluminium compounds, parabens and phthalates in combination with silver nanoparticles (AgNP, 15 and 45 nm by STEM, Ag15 and Ag45, respectively) on cell lines of the human breast epithelium, normal (MCF-10A) and transformed (MDA-MB-231 and MCF-7). Combination indices were the most spectacular at effective concentrations (ED) inducing 25 % decrease in viability for the combinations of Ag15 with AlCl₃ for MDA-MB-231 cells or aluminium zirconium tetrachlorohydrex Gly (AlZr) for MCF-10A and MCF-7 cells, where rather strong antagonism was revealed. As the ED values increased, those effects were enhanced (e.g. Ag15+AlCl₃ for MDA-MB-231) or reversed into synergism (e.g. Ag15+AlZr for MCF-7). Another strong effect was observed for aluminium chloride hydroxide, which increasing ED, induced synergistic effect with both Ag15 and Ag45 on MCF-10A cells. Another interesting synergistic effect was observed for DBPh, but only in combination with Ag45 on MCF-10A and MCF-7. The results on cytotoxicity, cell cycle and oxidative stress induction indicate complex response of the cell lines to combined treatment with silver nanoparticles and the chemicals, which were influenced by diverse factors, such as physico-chemical characteristics of AgNP, method of their synthesis, concentrations used, and finally cell type.

Alleviating effects of reduced graphene oxide against lead-induced cytotoxicity and oxidative stress in human alveolar epithelial (A549) cells

Broad application of reduced graphene oxide (rGO) and ubiquitous lead (Pb) pollution may increase the possibility of combined exposure of humans. Information on the combined effects of rGO and Pb in human cells is scarce. This work was designed to explore the potential effects of rGO on Pb-induced toxicity in human alveolar epithelial (A549) cells. Prepared rGO was polycrystalline in nature. The formation of a few layers of visible creases and silky morphology due to high aspect ratio was confirmed. Low level (25 μg/mL) of rGO was not toxic to A549 cells. However, Pb exposure (25 μg/mL) induced cell viability reduction, lactate dehydrogenase enzyme leakage with rounded morphology in A549 cells. Remarkably, Pb-induced cytotoxicity was significantly mitigated by rGO co-exposure. Pb-induced mitochondrial membrane potential loss, cell cycle arrest and higher activity of caspase-3 and -9 enzymes were also alleviated by rGO co-exposure. Moreover, we observed that Pb exposure causes generation of pro-oxidants (e.g., reactive oxygen species, hydrogen peroxide and lipid peroxidation) and antioxidant depletion (e.g., glutathione and antioxidant enzymes). In addition, the effects of Pb on pro-oxidant and antioxidant markers were significantly reverted by GO co-exposure. Inductively coupled plasma-mass spectrometry suggested that due to the adsorption of Pb on rGO sheets, accessibility of Pb ions for A549 cells was limited. Hence, rGO reduced the toxicity of Pb in A549 cells. This research warrants further study to work on detailed underlying mechanisms of the mitigating effects of rGO against Pb-induced toxicity on a molecular level.

Investigation of Cytotoxicity, Apoptosis, and Oxidative Stress Response of Fe3O4-RGO Nanocomposites in Human Liver HepG2 cells

Iron oxide–reduced graphene oxide (Fe₃O₄-RGO) nanocomposites have attracted enormous interest in the biomedical field. However, studies on biological response of Fe₃O₄-RGO nanocomposites at the cellular and molecular level are scarce. This study was designed to synthesize, characterize, and explore the cytotoxicity of Fe₃O₄-RGO nanocomposites in human liver (HepG2) cells. Potential mechanisms of cytotoxicity of Fe₃O₄-RGO nanocomposites were further explored through oxidative stress. Prepared samples were characterized by UV-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy. The results demonstrated that RGO induce dose-dependent cytotoxicity in HepG2 cells. However, Fe₃O₄-RGO nanocomposites were not toxic. We further noted that RGO induce apoptosis in HepG2 cells, as evidenced by mitochondrial membrane potential loss, higher caspase-3 enzyme activity, and cell cycle arrest. On the other hand, Fe₃O₄-RGO nanocomposites did not alter these apoptotic parameters. Moreover, we observed that RGO increases intracellular reactive oxygen species and hydrogen peroxide while decrease antioxidant glutathione. Again, Fe₃O₄-RGO nanocomposites did not exert oxidative stress. Altogether, we found that RGO significantly induced cytotoxicity, apoptosis and oxidative stress. However, Fe₃O₄-RGO nanocomposites showed good biocompatibility to HepG2 cells. This study warrants further research to investigate the biological response of Fe₃O₄-RGO nanocomposites at the gene and molecular level.

Tyrosol prevents AlCl3 induced male reproductive damage by suppressing apoptosis and activating the Nrf-2/HO-1 pathway

Aluminium is a ubiquitous element that occurs naturally in the soil making human exposure to it is unavoidable. Tyrosol is present in olive oil and is known to have antioxidant effects. Therefore, the present study explores the toxic effects of aluminium chloride (AlCl₃ ) and evaluates the possible protection by tyrosol in male rats. Testicular injury was induced by the administration of AlCl₃ (34 mg kg^-1  day^-1 ). Rats were treated with either tyrosol (20 mg kg^-1 day^-1 ) or AlCl3 (34 mg kg^-1 day^-1 ). The experiment lasted for 10 weeks. Biochemical, histopathological and protein expression profiles were determined to decipher the role of tyrosol in protecting the cellular damage. Further, histomorphometric analyses of testes showed deranged architecture along with other noted abnormalities. AlCl₃ group rats' testes showed decreased GSH levels, CAT activities, Nrf-2, HO-1, bcl-2 expressions and sperm motility whereas increased caspase-3 expressions, MDA levels, abnormal and dead/live sperm ratio. However, tyrosol treatment attenuated these changes. The present results demonstrate the beneficial role of tyrosol treatment in AlCl₃ induced testicular toxicity alterations of rat.

Evaluation of the Cytotoxicity and Oxidative Stress Response of CeO2-RGO Nanocomposites in Human Lung Epithelial A549 Cells

Graphene-based nanocomposites have attracted enormous interest in nanomedicine and environmental remediation, owing to their unique characteristics. The increased production and widespread application of these nanocomposites might raise concern about their adverse health effects. In this study, for the first time, we examine the cytotoxicity and oxidative stress response of a relatively new nanocomposite of cerium oxide-reduced graphene oxide (CeO₂-RGO) in human lung epithelial (A549) cells. CeO₂-RGO nanocomposites and RGO were prepared by a simple hydrothermal method and characterized by relevant analytical techniques. Cytotoxicity data have shown that RGO significantly induces toxicity in A549 cells, evident by cell viability reduction, membrane damage, cell cycle arrest, and mitochondrial membrane potential loss. However, CeO₂-RGO nanocomposites did not cause statistically significant toxicity as compared to a control. We further observed that RGO significantly induces reactive oxygen species generation and reduces glutathione levels. However, CeO₂-RGO nanocomposites did not induce oxidative stress in A549 cells. Interestingly, we observed that CeO₂ nanoparticles (NPs) alone significantly increase glutathione (GSH) levels in A549 cells as compared to a control. The GSH replenishing potential of CeO₂ nanoparticles could be one of the possible reasons for the biocompatible nature of CeO₂-RGO nanocomposites. Our data warrant further and more advanced research to explore the biocompatibility/safety mechanisms of CeO₂-RGO nanocomposites in different cell lines and animal models.

Flexural strength, biocompatibility, and antimicrobial activity of a polymethyl methacrylate denture resin enhanced with graphene and silver nanoparticles

OBJECTIVE

The study evaluates the effect of adding graphene-Ag nanoparticles (G-AgNp) to a PMMA auto-polymerizing resin, with focus on antibacterial activity, cytotoxicity, monomer release, and mechanical properties.

MATERIALS AND METHODS

Auto-polymerizing acrylic resin (M) was loaded with 1 wt% G-AgNp (P1) and 2 wt% G-AgNp (P2). Methyl methacrylate monomer release (MMA) was measured after immersion of the samples in chloroform and cell medium respectively. Cell viability was assessed on dysplastic oral keratinocytes (DOK) and dental pulp stem cells. Oxidative stress and inflammatory response following exposure of dysplastic oral keratinocytes to the experimental resins was evaluated. Antibacterial activity against Staphylococcus aureus, Streptococcus mutans and Escherichia coli and also flexural strength of the resins were assessed.

RESULTS

Residual monomer: For samples immersed in chloroform, MMA concentration reached high levels, 10.27 μg/g for sample P1; MMA increased at higher G-AgNp loading; 0.63 μg/g MMA was found in medium for P1, and less for sample P2. Cell viability: Both cell lines displayed a viability decrease, but remained above 75%, compared to controls, when exposed to undiluted samples. Inflammation: proinflammatory molecule TNF-α decreased when DOK cultures were exposed to G-AgNp samples. MDA levels indicated increased oxidative stress damage in cells treated with PMMA, confirmed by the antioxidant mechanism activation, while samples containing G-AgNp induced an antioxidant effect. All tested samples showed antibacterial properties against Gram-positive bacteria. Samples containing G-AgNp also exhibited bactericide action on E. coli. Mechanical properties: both samples containing G-AgNp improved flexural strength compared to the sample resin, measured through elastic strength parameters.

CONCLUSIONS

PMMA resin loaded with G-AgNp presents promising antibacterial activity associated with minimal toxicity to human cells, in vitro, as well as improved flexural properties.

CLINICAL RELEVANCE

These encouraging results obtained in vitro support further in vivo investigation, to thoroughly check whether the PMMA loaded with graphene-silver nanoparticles constitute an improvement over current denture materials.

Melatonin alleviates aluminium chloride-induced immunotoxicity by inhibiting oxidative stress and apoptosis associated with the activation of Nrf2 signaling pathway

The present study aimed to investigate whether melatonin (MT) treatment can attenuate immunotoxicity induced by aluminum chloride (AlCl₃) in rat spleen. Forty-eight healthy male Wistar rats were randomly allocated and treated with AlCl₃ and/or MT. Rats were orally administered with AlCl₃ for 90 days, from 61st days, rats were injected intraperitoneally with MT for 30 days. Firstly, we found that MT relieved the AlCl₃-induced immunosuppression by improving spleen structural damage, CD3⁺ and CD4⁺ T lymphocyte subsets, IL-2 and TNF-α mRNA expressions and decreasing CD8⁺ T lymphocyte subsets. Secondly, MT attenuated the AlCl₃-induced oxidative stress in rat spleen by decreasing the levels of ROS and MDA, while increasing the activities of SOD and CAT. Thirdly, MT relieved the AlCl₃-induced apoptosis in rat spleen by increasing the MMP and Bcl-2 mRNA and protein expressions, while decreasing apoptosis rates, activity of Caspase-3 and pro-apoptotic gene expression. Finally, MT increased Nrf2 nuclear translocation, and Nrf2 target genes (HO-1, NQO1, SOD1 and CAT) mRNA expressions in the spleen of AlCl₃-exposed rat. These results suggest that MT may alleviate AlCl₃-induced immunotoxicity by inhibiting oxidative stress and apoptosis associated with the activation of Nrf2 signaling pathway, which could lay the foundation for the treatment of AlCl₃ immunotoxicity.

Kidney-targeted triptolide-encapsulated mesoscale nanoparticles for high-efficiency treatment of kidney injury

Insolubility and toxicity of TP restrict clinical applications in renal diseases. Here, TP-encapsulated mesoscale nanoparticles offer a new therapeutic strategy for renal diseases due to good biocompability, kidney targeting and slow release.