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Cobalt (Co) and Nickel (Ni) are used nowadays in various industrial applications like lithium-ion batteries, raising concerns about their environmental release and public health threats. Both metals are potentially carcinogenic and may cause neurological and cardiovascular dysfunctions, though underlying toxicity mechanisms have to be further elucidated. This study employs untargeted transcriptomics to analyze downstream cellular effects of individual and combined Co and Ni toxicity in human liver carcinoma cells (HepG2). The results reveal a synergistic effect of Co and Ni, leading to significantly higher number of differentially expressed genes (DEGs) compared to individual exposure. There was a clear enrichment of Nrf2 regulated genes linked to pathways such as glycolysis, iron and glutathione metabolism, and sphingolipid metabolism, confirmed by targeted analysis. Co and Ni exposure alone and combined caused nuclear Nrf2 translocation, while only combined exposure significantly affects iron and glutathione metabolism, evidenced by upregulation of HMOX-1 and iron storage protein FTL. Both metals impact sphingolipid metabolism, increasing dihydroceramide levels and decreasing ceramides, sphingosine and lactosylceramides, along with diacylglycerol accumulation. By combining transcriptomics and analytical methods, this study provides valuable insights into molecular mechanisms of Co and Ni toxicity, paving the way for further understanding of metal stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Metal ions stress will inhibit the oxidation capacity of iron and sulfur of an acidophilic microbial consortium (AMC), which leads to reduced bioleaching efficiency. This work explored the impacts of Li + and Co 2+ on the composition and function of AMC biofilms with a multi-scale approach. At the reactor scale, the results indicated that the oxidative activity, the adsorption capacity, and the biofilm formation ability of AMC on pyrite surfaces decreased under 500 mM Li + and 500 mM Co 2+ . At the biofilm scale, the electrochemical measurements showed that Li + and Co 2+ inhibited the charge transfer between the pyrite working electrode and the biofilm, and decreased the corrosion current density of the pyrite working electrode. At the cell scale, the content of proteins in extracellular polymers substrate (EPS) increased as the concentrations of metal ions increased. Moreover, the adsorption capacity of EPS for Li + and Co 2+ increased. At the microbial consortium scale, a BugBase phenotype analysis showed that under 500 mM Li + and 500 mM Co 2+ , the antioxidant stress capacity and the content of mobile gene elements in AMC increased. The results in this work can provide useful data and theoretical support for the regulation strategy of the bioleaching of spent lithium-ion batteries to recover valuable metals., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The present investigation was undertaken to evaluate the toxic effects of CoCl 2 -induced hepatotoxicity and fatty acid changes in juvenile Cyprinus carpio. Fish were divided into six experimental groups in duplicate. The first group served as controls. The second group received the lowest exposure dose at 2.5 µg/L. In the third group, fish were exposed to 25 µg/L of CoCl 2 . The fourth group was exposed to 50 µg/L of CoCl 2 . The last two groups were exposed to the highest doses, 100 and 500 µg/L of CoCl 2 . Total antioxidant activities were estimated using a colorimetric method. Liver fatty acid compositions were analyzed by high-performance gas chromatography (GC). Hepatopathy was identified through microscopic analysis. Exposure of C. carpio to CoCl 2 resulted in hepatotoxicity, indicated by increased levels of malondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ), protein carbonyls (PCO), and alterations in the ferric reducing antioxidant power system (FRAP). Superoxide dismutase (SOD), glutathione-S-transferase (GST), glutathione peroxidase (GPx), reduced glutathione (GSH), metallothioneins (MTs), and low thiol levels (L-SH) significantly increased, particularly under exposure to the highest CoCl 2 doses (100 and 500 µg/L). Acetylcholinesterase activity decreased significantly in C. carpio exposed to graded CoCl 2 doses. Additionally, there was a decrease in polyunsaturated fatty acids (PUFA), primarily n-3 PUFA, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), while an increase in monounsaturated (MUFA) and saturated fatty acids (SFA), including palmitic (C16:0), stearic (C18:0), palmitoleic (C16:1), and oleic (C18:1) acids, was observed. Histopathological examination of the liver confirmed hepatopathy revealing characteristic tissue changes such as leucocyte infiltration, hepatic cell membrane degradation, vacuolization, and lipid inclusions. The study provided ethnophysiology insights into the responses of C. carpio to CoCl 2 -induced oxidative stress and lipidomic alteration, underscoring its potential as a bioindicator for assessing environmental impacts and metal contamination., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The utilization of Cobalt (Co) has surged due to it is critical role in renewable energy technologies and other high-tech applications. Concurrently, the potential health risks associated with Co exposure have raised concerns. Previous studies, including our own, have shown that Co can impair learn and memory functions as an epigenetic hazard, even at low concentrations. In this study, we explore the mechanisms of Co-induced ferroptosis in neurodegenerative damage both in vivo and in vitro, focusing on the epigenetic regulation by N6-methyladenosine (m 6 A) demethylase alkB homolog 5 (ALKBH5). We identify heme oxygenase-1 (HO-1) as a direct target gene of ALKBH5, playing a crucial role in mitigating Co-induced ferroptosis. ALKBH5 deficiency affects the post-transcriptional regulation of HO-1 through m 6 A modification, which in turn influences mRNA's stability, intracellular distribution, and alternative splicing, thereby enhancing susceptibility to Co-induced ferroptosis. Additionally, we discuss the potential involvement of heterogeneous nuclear ribonucleoprotein M (hnRNPM) in regulating alternative splicing of HO-1 mRNA, potentially mediated by m 6 A modifications. This study provides new epigenetic insights into the post-transcriptional regulatory mechanisms involved in Co-induced ferroptosis and highlights the broader implications of environmental hazards in neurodegenerative damage., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

There is increasing evidence that the imbalance of metals as cobalt (Co) and chromium (Cr) may increase the risk of development and progression of neurodegenerative diseases (NDDs). The human exposure to Co and Cr is derived mostly from industry, orthopedic implants, and polluted environments. Neurological effects of Co and Cr include memory deficit, olfactory dysfunction, spatial disorientation, motor neuron disease, and brain cancer. Mechanisms of Co and Cr neurotoxicity included DNA damage and genomic instability, epigenetic changes, mitochondrial disturbance, lipid peroxidation, oxidative stress, inflammation, and apoptosis. This paper seeks to overview the Co and Cr sources, the mechanisms by which these metals induce NDDs, and their levels in fluids of the general population and patients affected by NDDs. To this end, evidence of Co and Cr unbalance in the human body, mechanistic data, and neurological symptoms were collected using in vivo mammalian studies and human samples., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The widespread utilization of plastic and cobalt alloy products in industries and medicine has led to the increased presence of their degradation byproducts, microplastics (MPs), and cobalt nanoparticles (Co NPs), in the environment and organisms. While these particles can circulate throughout the body via the circulatory system, their specific adverse effects and mechanisms on the vascular system remain unclear. Employing scanning electron microscope (SEM) analysis and other methodologies, we demonstrate the potential adsorption and aggregation phenomena between MPs and Co NPs. In vitro experiments illustrate that ingestion of either MPs or Co NPs compromises vascular endothelial cell function and induces the generation of reactive oxygen species (ROS). Notably, this effect is markedly attenuated when a combination of MPs and Co NPs is administered compared to MPs alone. Additionally, zebrafish experiments validate our in vitro findings. Mechanistic studies have demonstrated that both MPs and Co NPs induce aberrant Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Intriguingly, a weaker activation level is observed when these agents are administered in combination compared to when they are administered individually. Our study provides novel insights into the interaction between MPs and Co NPs and their detrimental effects on vascular endothelial cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this article., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Even while accelerated cardiomyocyte apoptosis is one of the primary causes of cardiac damage, the underlying mechanism is still mostly unknown. In addition to examining potential protective effects of bisoprolol and diosmin against CoCl2-induced cardiac injury, the goal of this study was to identify potential mechanisms regulating the hypoxic cardiac damage caused by cobalt chloride (CoCl2). For a period of 21 days except Cocl2 14 days from the first day of the experiment, rats were split into the following groups: Normal control group, rats received vehicle only (2 ml/kg/day, p.o.), (Cocl2, 150 mg/kg/day, p.o.), bisoprolol (25 mg/kg/day, p.o.); diosmin (100 mg/kg/day, p.o.) and bisoprolol + diosmin + Cocl2 groups. At the end of the experimental period, serum was taken for estimation of cardiac function, lipid profile, and pro/anti-inflammatory cytokines. Moreover, tissue samples were collected for evaluation of oxidative stress, endothelial dysfunction, α-SMA, PKC-α, MiR-143-3P, MAPK, ERK5, MCP-1, CXCR4, Orai-1, and STIM-1. Diosmin and bisoprolol, either alone or in combination, enhance heart function by reducing abnormalities in the electrocardiogram and the hypotension brought on by CoCl2. Additionally, they significantly ameliorate endothelial dysfunction by downregulating the cardiac expressions of α-SMA, PKC-α, MiR-143-3P, MAPK, ERK5, MCP-1, CXCR4, Orai-1, and STIM-1. Bisoprolol and diosmin produced modulatory activity against inflammatory state, redox balance, and atherogenic index concurrently. Together, diosmin and bisoprolol, either alone or in combination, significantly reduced all the cardiac alterations brought on by CoCl2. The capacity to obstruct hypoxia-induced α-SMA, PKC-α, MiR-143-3P/MAPK/MCP-1, MiR-143-3P/ERK5/CXCR4, Orai-1/STIM-1 signaling activation, as well as their anti-inflammatory, antioxidant, and anti-apoptotic properties, may be responsible for these cardio-protective results., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

There has been increasing attention given to nickel-cobalt tailings (NCT), which pose a risk of heavy metal pollution in the field. In this study, on site tests and sampling analysis were conducted to assess the physical and chemical characteristics, heavy metal toxicity, and microbial diversity of the original NCT, solidified NCT, and the surrounding soil. The research results show that the potential heavy metal pollution species in NCT are mainly Ni, Co, Mn, and Cu. Simultaneous solidification and passivation of heavy metals in NCT were achieved, resulting in a reduction in biological toxicity and a fivefold increase in seed germination rate. The compressive strength of the original tailings was increased by 20 times after solidification. The microbial diversity test showed that the abundance of microbial community in the original NCT was low and the population was monotonous. This study demonstrates, for the first time, that the use of NCT for solidification in ponds can effectively solidification of heavy metals, reduce biological toxicity, and promote microorganism diversity in mining areas (tended to the microbial ecosystem in the surrounding soil). Indeed, this study provides a new perspective for the environmental remediation of metal tailings., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

As innovative and versatile agents with potential applications in a wide range of fields including medicine, electronics, wastewater treatment, cosmetics, and energy storage devices, magnetic nanoparticles (NPs) are significant attention. However, our knowledge of the harmful effects of different-sized NPs, particularly of their effects on aquatic animals, is limited. In this study, we evaluated the impact of different-sized (sub-2, 5, and 15 nm) cobalt ferrite (CoFe 2 O 4 ) NPs on the biological parameters of rainbow trout (Oncorhynchus mykiss) embryos and larvae. The NPs were characterized using techniques such as high-resolution transmission electron microscopy (HRTEM) for imaging, X-ray diffraction (XRD) for crystallographic analysis, and energy-dispersive X-ray spectroscopy (EDX) for elemental analysis, and were tested for impact through a series of toxicity, genotoxicity, and biochemical assays at a concentration of 100 mg/L. The obtained results showed that toxicity of CoFe 2 O 4 NPs depended on the size of NPs and the developmental stage of the fish. Our results, which revealed significant changes in biological parameters of O. mykiss under exposure to CoFe 2 O 4 NPs, imply that these NPs may be not environmentally safe. The hierarchical cluster analysis showed that embryos of the control group were clearly separated from those exposed to NPs of various sizes. However, in the exposed larvae, the effects of control and the smallest-sized NPs (sub-2 nm) differed from those induced by larger NPs (5 nm and 15 nm). Additional research is necessary to comprehend the mechanisms underlying the observed variations, which would be advantageous for both managing the risk of NPs to humans and advancing the field of aquatic nanotoxicology., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The two trace elements cobalt (Co) and nickel (Ni) are widely distributed in the environment due to the increasing industrial application, for example in lithium-ion batteries. Both metals are known to cause detrimental health impacts to humans when overexposed and both are supposed to be a risk factor for various diseases. The individual toxicity of Co and Ni has been partially investigated, however the underlying mechanisms, as well as the interactions of both remain unknown. In this study, we focused on the treatment of liver carcinoma (HepG2) and astrocytoma (CCF-STTG1) cells as a model for the target sites of these two metals. We investigated their effects in single and combined exposure on cell survival, cell death mechanisms, bioavailability, and the induction of oxidative stress. The combination of CoCl 2 and NiCl 2 resulted in higher Co levels with subsequent decreased amount of Ni compared to the individual treatment. Only CoCl 2 and the combination of both metals led to RONS induction and increased GSSG formation, while apoptosis and necrosis seem to be involved in the cell death mechanisms of both CoCl 2 and NiCl 2 . Collectively, this study demonstrates cell-type specific toxicity, with HepG2 representing the more sensitive cell line. Importantly, combined exposure to CoCl 2 and NiCl 2 is more toxic than single exposure, which may originate partly from the respective cellular Co and Ni content. Our data imply that the major mechanism of joint toxicity is associated with oxidative stress. More studies are needed to assess toxicity after combined exposure to elements such as Co and Ni to advance an improved hazard prediction for less artificial and more real-life exposure scenarios., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Untargeted metabolomics is a non-a priori analysis of biomolecules that characterizes the metabolome variations induced by short- and long-term exposures to stressors. Even if the metabolite annotation remains lacunar due to database gaps, the global metabolomic fingerprint allows for trend analyses of dose-response curves for hundreds of cellular metabolites. Analysis of dose/time-response curve trends (biphasic or monotonic) of untargeted metabolomic features would thus allow the use of all the chemical signals obtained in order to determine stress levels (defense or damage) in organisms. To develop this approach in a context of time-dependent microbial community changes, mature river biofilms were exposed for 1 month to four cobalt (Co) concentrations (from background concentration to 1 × 10 -6  M) in an open system of artificial streams. The meta-metabolomic response of biofilms was compared against a multitude of biological parameters (including bioaccumulation, biomass, chlorophyll a content, composition and structure of prokaryotic and eukaryotic communities) monitored at set exposure times (from 1 h to 28 d). Cobalt exposure induced extremely rapid responses of the meta-metabolome, with time range inducing defense responses (TRIDeR) of around 10 s, and time range inducing damage responses (TRIDaR) of several hours. Even in biofilms whose structure had been altered by Co bioaccumulation (reduced biomass, chlorophyll a contents and changes in the composition and diversity of prokaryotic and eukaryotic communities), concentration range inducing defense responses (CRIDeR) with similar initiation thresholds (1.41 ± 0.77 × 10 -10  M Co 2+ added in the exposure medium) were set up at the meta-metabolome level at every time point. In contrast, the concentration range inducing damage responses (CRIDaR) initiation thresholds increased by 10 times in long-term Co exposed biofilms. The present study demonstrates that defense and damage responses of biofilm meta-metabolome exposed to Co are rapidly and sustainably impacted, even within tolerant and resistant microbial communities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The response of the meta-metabolome is rarely used to characterize the effects of contaminants on a whole community. Here, the meta-metabolomic fingerprints of biofilms were examined after 1, 3 and 7 days of exposure to five concentrations of cobalt (from background concentration to 1 × 10 -5 M) in aquatic microcosms. The untargeted metabolomic data were processed using the DRomics tool to build dose-response models and to calculate benchmark-doses. This approach made it possible to use 100% of the chemical signal instead of being limited to the very few annotated metabolites (7%). These benchmark-doses were further aggregated into an empirical cumulative density function. A trend analysis of the untargeted meta-metabolomic feature dose-response curves after 7 days of exposure suggested the presence of a concentration range inducing defense responses between 1.7 × 10 -9 and 2.7 × 10 -6 M, and of a concentration range inducing damage responses from 2.7 × 10 -6 M and above. This distinction was in good agreement with changes in the other biological parameters studied (biomass and chlorophyll content). This study demonstrated that the molecular defense and damage responses can be related to contaminant concentrations and represents a promising approach for environmental risk assessment of metals., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Curcumin, a bioactive polyphenol derived from turmeric, has been reported to have anti-inflammatory properties. The current study investigated the anti-inflammatory effect of curcumin in the hippocampal subfields (CA1 and CA3) after exposure to cobalt (Co) and the impact of ERK protein. Twenty-eight albino Wistar rats were divided into four groups, each with seven randomly selected rats as follows: Control (distilled water), Cobalt (Co) only (40 mg/kg), 120 mg/kg or 240 mg/kg curcumin + Co (40 mg/kg). Treatment was via oral gavage for 28 days. We performed a biochemical investigation to determine the levels of proinflammatory cytokines (TNFα and IL-1β). Furthermore, we conducted an immunohistochemical evaluation to assess the expression of IBA1 by microglial cells and the immunoexpression of ERK protein in the hippocampus. Results revealed a significant (p<0.05) elevation in the tissue level of TNFα and IL-1β, an increase in the number of IBA1-positive microglia, and upregulation of ERK protein in the hippocampal subfields of the rats after exposure to cobalt-only. Nevertheless, pretreatment with curcumin restored these parameters to levels comparable to control. In conclusion, our results showed that curcumin abrogated the Co-induced neuroinflammation by suppressing the release of proinflammatory biomarkers, reducing microgliosis, and modulating the ERK/MAPK pathway., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Cobalt-chromium-molybdenum (CoCrMo) alloys are routinely used in arthroplasty. CoCrMo wear particles and ions derived from arthroplasty implants lead to macrophage-driven adverse local tissue reactions, which have been linked to an increased risk of periprosthetic joint infection after revision arthroplasty. While metal-induced cytotoxicity is well characterized in human macrophages, direct effects on their functionality have remained elusive. Synchrotron radiation X-ray microtomography and X-ray fluorescence mapping indicated that peri-implant tissues harvested during aseptic revision of different arthroplasty implants are exposed to Co and Cr in situ. Confocal laser scanning microscopy revealed that macrophage influx is predominant in patient tissue. While in vitro exposure to Cr 3+ had only minor effects on monocytes/macrophage phenotype, pathologic concentrations of Co 2+ significantly impaired both, monocyte/macrophage phenotype and functionality. High concentrations of Co 2+ led to a shift in macrophage subsets and loss of surface markers, including CD14 and CD16. Both Co 2+ and Cr 3+ impaired macrophage responses to Staphylococcus aureus infection, and particularly, Co 2+ -exposed macrophages showed decreased phagocytic activity. These findings demonstrate the immunosuppressive effects of locally elevated metal ions on the innate immune response and support further investigations, including studies exploring whether Co 2+ and Cr 3+ or CoCrMo alloys per se expose the patients to a higher risk of infections post-revision arthroplasty.

Cobalt is widely used in the medical industry, mainly including cobalt alloy joint implants and cobalt-chromium porcelain crowns. However, unexplained ototoxicity and neurotoxicity often occur in the clinical use of cobalt agents at present, which limits the development of the cobalt industry. In this study, based on the clinical problem of cobalt ototoxicity, we first conducted an extensive search and collation of related theories, and on this basis, prepared an HEI-OC1 cell model and basilar membrane organotypic cultures after cobalt treatment. We used immunofluorescence staining, western blot, CCK8, and si-RNA to investigate the mechanism of cobalt ototoxicity, to discover its potential therapeutic targets. After comparing the reactive oxygen species, mitochondrial transmembrane potential, apoptosis-related protein expression, and cell viability of different treatment groups, the following conclusions were drawn: cobalt causes oxidative stress in the inner ear, which leads to apoptosis of inner ear cells; inhibition of oxidative stress and apoptosis can alleviate the damage of cobalt on inner ear cells; and the Dicer protein plays a role in the mechanism of inner ear damage and is a potential target for the treatment of cobalt-induced inner ear damage. Taken together, these results suggest that cobalt-induced ototoxicity triggered by oxidative stress activates a cascade of apoptotic events where cCaspase-3 decreases Dicer levels and amplifies this apoptotic pathway. It may be possible to prevent and treat cobalt ototoxicity by targeting this mechanism., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Hypoxia chambers have traditionally been used to induce hypoxia in cell cultures. Cellular responses to hypoxia can also be mimicked with the use of chemicals such as cobalt chloride (CoCl 2 ), which stabilizes hypoxia-inducible factor alpha-subunit proteins. In studies of ocular cells using primary cells and cell lines, such as Müller glial cell (MGC) lines, photoreceptor cell lines, retinal pigment epithelial (RPE) cell lines and retinoblastoma cell lines oxygen levels employed in hypoxia chambers range typically between 0.2% and 5% oxygen. For chemical induction of hypoxic response in these cells, the CoCl 2 concentrations used typically range from 100 to 600 μM. Here, we describe simplified protocols for stabilizing cellular hypoxia-inducible factor-1α (HIF-1α) in cell culture using either a hypoxia chamber or CoCl 2 . In addition, we also provide a detailed methodology to confirm hypoxia induction by the assessment of protein levels of HIF-1α, which accumulates in response to hypoxic conditions. Furthermore, we provide a summary of conditions applied in previous studies of ocular cells., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Cobalt exposure, even at low concentrations, induces neurodegenerative damage, such as Alzheimer's disease (AD). The specific underlying mechanisms remain unclear. Our previous study demonstrated that m 6 A methylation alteration is involved in cobalt-induced neurodegenerative damage, such as in AD. However, the role of m 6 A RNA methylation and its underlying mechanisms are poorly understood. In this study, both epidemiological and laboratory studies showed that cobalt exposure could downregulate the expression of the m 6 A demethylase ALKBH5, suggesting a key role for ALKBH5. Moreover, Methylated RNA immunoprecipitation and sequencing (MeRIP-seq) analysis revealed that ALKBH5 deficiency is associated with neurodegenerative diseases. KEGG pathway and Gene ontology analyses further revealed that the differentially m 6 A-modified genes resulting from ALKBH5 downregulation and cobalt exposure were aggregated in the pathways of proliferation, apoptosis, and autophagy. Subsequently, ALKBH5 deficiency was shown to exacerbate cell viability decline, motivate cell apoptosis and attenuate cell autophagy induced by cobalt with experimental techniques of gene overexpression/inhibition. In addition, morphological changes in neurons and the expression of AD-related proteins, such as APP, P-Tau, and Tau, in the cerebral hippocampus of wild-type and ALKBH5 knockout mice after chronic cobalt exposure were also investigated. Both in vitro and in vivo results showed that lower expression of ALKBH5 aggravated cobalt-induced neurodegenerative damage. These results suggest that ALKBH5, as an epigenetic regulator, could be a potential target for alleviating cobalt-induced neurodegenerative damage. In addition, we propose a novel strategy for the prevention and treatment of environmental toxicant-related neurodegeneration from an epigenetic perspective., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Cobalt is the most widely used heavy metal pollutant in medicine and industry. Excessive cobalt exposure can adversely affect human health. Neurodegenerative symptoms have been observed in cobalt-exposed populations; however, the underlying mechanisms remain largely unknown. In this study, we demonstrate that the N6-methyladenosine (m 6 A) demethylase fat mass and obesity-associated gene (FTO) mediates cobalt-induced neurodegeneration by impairing autophagic flux. Cobalt-induced neurodegeneration was exacerbated through FTO genetic knockdown or repression of demethylase activity, but was alleviated by FTO overexpression. Mechanistically, we showed that FTO regulates TSC1/2-mTOR signaling pathway by targeting TSC1 mRNA stability in an m 6 A-YTHDF2 manner, which resulted in autophagosome accumulation. Furthermore, FTO decreases lysosome-associated membrane protein-2 (LAMP2) to inhibit the integration of autophagosomes and lysosomes, leading to autophagic flux damage. In vivo experiments further identified that central nervous system (CNS)-Fto-specific knockout resulted in serious neurobehavioral and pathological damage as well as TSC1-related autophagy impairment in cobalt-exposed mice. Interestingly, FTO-regulated autophagy impairment has been confirmed in patients with hip replacement. Collectively, our results provide novel insights into m 6 A-modulated autophagy through FTO-YTHDF2 targeted TSC1 mRNA stability, revealing cobalt is a novel epigenetic hazard that induces neurodegeneration. These findings suggest the potential therapeutic targets for hip replacement in patients with neurodegenerative damage., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Particulate and soluble debris are generated by mechanical and non-mechanical degradation of implanted medical devices. Debris containing cobalt and chromium (CoCr) is known to cause adverse biological reactions. Implant-related complications are often diagnosed using radiography, which results in more frequent patient exposure to ionizing radiation. The aim of this study was to evaluate the potential for increased toxicity due to combined radiation and CoCr exposure. This was investigated using a controlled in vitro model consisting of commercially available CoCr debris that was generated from components of hip replacements and human cell lines relevant to the joint environment: endothelial HMEC-1 and synovial SW982. Particle sizes and shapes were heterogenous. Cells tended to internalize smaller particles, as observed by electron microscopy. Indicators of toxicity were measured after short (24 h after radiation) or extended (12-14 d after radiation) exposure timelines. In the short-term, CoCr reduced cell viability, increased apoptosis, and increased oxidative stress. The effects of radiation were not apparent until the timeline was extended. CoCr and radiation reduced cell survival, with both additive and synergistic effects. Mechanisms for reduced survival included rapid cell death caused by CoCr and senescence caused by radiation. In conclusion, results showed combined toxicological effects of CoCr and radiation at the doses and timelines used for this in vitro model. These observations warrant further investigation using other experimental models to determine translational impact.

Cobalt is an environmental toxicant, and excessive bodily exposure can damage the nervous system. Particularly, our previous study reported that low-dose cobalt (significantly less than the safety threshold) is still able to induce neurodegenerative changes. However, the underlying molecular mechanism is still insufficient revealed. Herein, we further investigate the molecular mechanism between cobalt-induced neurodegeneration and autophagy, as well as explore the interplay between hypoxia-inducible factor-1α (HIF-1α), reactive oxygen species (ROS), and autophagy in cobalt-exposed mice and human neuroglioma cells. We first reveal cobalt as an environmental toxicant to severely induce β amyloid (Aβ) deposition, tau hyperphosphorylation, and dysregulated autophagy in the hippocampus and cortex of mice. In particular, we further identify that cobalt-induced neurotoxicity is triggered by the impairment of autophagic flux in vitro experiments. Moreover, the mechanistic study reveals that cobalt exposure extremely activates HIF-1α expression to facilitate the overproduction of ROS. Then, elevated ROS can target the amino-threonine kinase (AKT)-mammalian target of rapamycin (mTOR)-Unc-51 like autophagy activating kinase 1 (ULK1) signaling pathway to participate in cobalt-induced impairment of autophagic flux. Subsequently, defected autophagy further exacerbates cobalt-induced neurotoxicity for its unable to eliminate the deposition of pathological protein. Therefore, our data provide scientific evidence for cobalt safety evaluation and risk assessment and propose a breakthrough for understanding the regulatory relationship between HIF-1α, ROS, and autophagy in cobalt-induced neurodegeneration., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest in this study., (Copyright © 2022. Published by Elsevier B.V.)

Metal-organic frameworks (MOFs) are emerging nanomaterials with widespread applications for their superior properties. However, the potential health and environmental risks of MOFs still need further understanding. In this work, we investigated the toxicity of a typical cobalt-based MOF (ZIF-67) with varied primary particle sizes (100, 200, 400, 700 and 1200 nm) to Photobacterium Phosphoreum T3 strain, a kind of luminescent bacteria. The luminescence inhibition rate of all ZIF-67 nanoparticles (NPs) reached 40 % and higher at the concentration of 5 mg/L, exhibiting strong toxicity. Combined cellular assays and gene expression analysis confirmed that the general bioactivity inhibition and oxidative damage were induced mainly by ZIF-67 NPs, rather than Co 2+ released from the ZIF-67 NPs. Additionally, the toxicity of ZIF-67 NPs demonstrated an evident size-dependent effect. For ZIF-67 smaller than 400 nm, the toxicity increased with the particle size decreased, while the trend was not significant when the particle size was larger than 400 nm. A potential explanation for this phenomenon is the smaller NPs (100 and 200 nm) may enter the cytoplasm, accumulating in the cytoplasm and causing more severe toxicity. Furthermore, Co 2+ released from the ZIF-67 NPs was not the primary contributor to the toxic effect of ZIF-67 NPs which was verified by the toxicity results and the variation of toxicity-related indicators. These findings provided insight into the better design and safer use of MOFs, and it also implied the potential environmental risk of the MOF's cannot be ignored, especially for the bioapplication., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)

As a result of the synthesis, three new solids, cobalt (II) coordination compounds with benzimidazole derivatives, and chlorides were obtained. The ligands that were used in the synthesis were specially synthesized and were commercially unavailable. During the synthesis, a single crystal of the complex with the L1 ligand was obtained and the crystal structure was refined. All coordination compounds were characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analysis. All the obtained data allowed one to determine the formulas of the new compounds, as well as to determine the method of metal-ligand coordination. Thermal analysis allowed to know the temperature stability of the compounds, solids intermediate and final products of pyrolysis. Additionally, volatile decomposition and fragmentation products have been identified. The toxicity of the compounds and their bioavailability were determined using in silico methods. By predicting activity on cell lines, the potential use of compounds as chemotherapeutic agents has been specified. The blood-brain barrier crossing and the gastrointestinal absorption were defined. Pharmaceutical biodistribution was also simulated.

Following accidental inhalation of radioactive cobalt particles, the poorly soluble and highly radioactive Co 3 O 4 particles are retained for long periods in lungs. To decrease their retention time is of crucial importance to minimize radiation-induced damage. As dissolved cobalt is quickly transferred to blood and eliminated by urinary excretion, enhancing the dissolution of particles would favor 60 Co elimination. We evaluated the ability of ascorbic acid alone or associated with the chelating agents DTPA 1 , DFOB 2 or EDTA 3 to enhance dissolution of cobalt particles after macrophage engulfment, and the drug effects on the translocation of the soluble species CoCl 2 through an epithelial barrier. We exposed differentiated THP-1 macrophage-like cells and Calu-3 lung epithelial cells cultured in a bicameral system to cobalt and selected molecules up to 7 days. DTPA, the recommended treatment in man, used alone showed no effect, whereas ascorbic acid significantly increased dissolution of Co 3 O 4 particles. An additional efficacy in intracellular particles dissolution was observed for combinations of ascorbic acid with DTPA and EDTA. Except for DFOB, treatments did not significantly modify translocation of dissolved cobalt across the epithelial lung barrier. Our study provides new insights for decorporating strategies following radioactive cobalt particle intake., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Cobalt intoxication is a rare cause of toxic opticopathy, and may be caused by metal endoprostheses. Since its clinical appearance is unspecific and the incidence low, diagnosis is challenging. Due to the dramatic consequences of delayed treatment, cobalt intoxication should be considered as a rare differential diagnosis of bilateral loss of vision in patients with appropriate history., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Pigments are among the oldest nanoparticulate products known to mankind, and their use in tattoos is also very old. Nowadays, 25% of American people aged 18 to 50 are tattooed, which poses the question of the delayed effects of tattoos. In this article, we investigated three cobalt [Pigment Violet 14 (purple color)] or cobalt alloy pigments [Pigment Blue 28 (blue color), Pigment Green 14 (green color)], and one zinc pigment [Pigment White 4 (white color)] which constitute a wide range of colors found in tattoos. These pigments contain microparticles and a significant proportion of submicroparticles or nanoparticles (in either aggregate or free form). Because of the key role of macrophages in the scavenging of particulate materials, we tested the effects of cobalt- and zinc-based pigments on the J774A.1 macrophage cell line. In order to detect delayed effects, we compared two exposure schemes: acute exposure for 24 hours and an exposure for 24 hours followed by a 3-day post-exposure recovery period. The conjunction of these two schemes allowed for the investigation of the delayed or sustained effects of pigments. All pigments induced functional effects on macrophages, most of which were pigment-dependent. For example, Pigment Green 19, Pigment Blue 28, and Pigment White 4 showed a delayed alteration of the phagocytic capacity of cells. Moreover, all the pigments tested induced a slight but significant increase in tumor necrosis factor secretion. This effect, however, was transitory. Conversely, only Pigment Blue 28 induced both a short and sustained increase in interleukin 6 secretion. Results showed that in response to bacterial stimuli (LPS), the secretion of tumor necrosis factor and interleukin 6 declined after exposure to pigments followed by a recovery period. For chemoattractant cytokines (MCP-1 or MIP-1α), delayed effects were observed with a secretion decreased in presence of Pigment Blue 28 and Pigment violet 14, both with or without LPS stimuli. The pigments also induced persisting changes in some important macrophage membrane markers such as CD11b, an integrin contributing to cell adhesion and immunological tolerance. In conclusion, the pigments induced functional disorders in macrophages, which, in some cases, persist long after exposure, even at non-toxic doses., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Devcic, Dussol, Collin-Faure, Pérard, Fenel, Schoehn, Carrière, Rabilloud and Dalzon.)

Cobalt, chromium, and nickel are used in orthopedic prostheses. They can be released, accumulate in many organs, and be toxic. The aim of this study is to evaluate the cytotoxicity of these metals on human hepatocytes and to improve our knowledge of their cellular toxicity mechanisms by metabolomic analysis. HepaRG cells were incubated for 48 h with increasing concentrations of metals to determine their IC 50 . Then, a nontargeted metabolomic study using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) was done at IC 50 and at a lower concentration (100 nM), near to those found in the blood and liver of patients with prostheses. IC 50 were defined at 940, 2, and 1380 μM for Co, Cr, and Ni, respectively. In vitro , Cr appears to be much more toxic than Co and Ni. Metabolomic analysis revealed the disruption of metabolic pathways from the low concentration of 100 nM, in particular tryptophan metabolism and lipid metabolism illustrated by an increase in phenylacetylglycine, a marker of phospholipidosis, for all three metals. They also appear to be responsible for oxidative stress. Dysregulation of these pathways impacts hepatocyte metabolism and may result in hepatotoxicity. Further investigations on accessible biological matrices should be conducted to correlate our in vitro results with the clinical data of prostheses-bearing patients.

A mode of action (MOA) for cobalt substances based on the "International Programme on Chemical Safety Conceptual Framework for Evaluating a MOA for Chemical Carcinogenesis" is presented. The data recorded therein were generated in a tiered testing program described in the preceding papers of this special issue, as well as data from the public domain. The following parameters were included in the evaluation: solubility of cobalt substances in artificial lung fluids (bioelution), in vitro biomarkers for cytotoxicity, reactive oxygen species and hypoxia mimicry, inhalation toxicity following acute exposure and repeated dose inhalation effects. Two distinct groups of cobalt substances emerged: substances inducing all effects across the MOA form one group, associated with the adverse outcome of lung cancer in rodents upon chronic exposure. Another group of cobalt substances induces no or very limited effects in the in vitro and acute testing. Higher tier testing with a representative of this group, tricobalt tetraoxide, showed a response resembling rat lung overload following exposure to high concentrations of poorly soluble particles. Based on the fundamental differences in the lower tier toxicological profile, cobalt substances with an unknown hazard profile can be assigned to either group based on lower tier testing alone., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Cobalt occurs naturally in the earth's crust, is essential to some microorganisms and forms the core of vitamin B12. Cobalt substances are used in numerous technologies, such as catalysts or batteries. Some of these substances are classified as Carcinogens, while other cobalt compounds have a hazard profile that is less understood and are missing long term studies like cancer bioassays. There is a strong interest by society and industry to reduce and -where possible- eliminate animal testing, yet a necessity by industry and authorities to have sufficient data for hazard conclusions and risk assessments. The present paper introduces a strategy for a mode of action-informed tiered testing, aimed at full inclusion of existing hazard data and selection of relevant biological events towards a certain adverse outcome, i.e. inhalation carcinogenicity. The occurrence of these events following exposure to various cobalt substances is investigated with in vitro and with limited in vivo testing. The tiers of testing are described in the companion papers of this RTP special issue. This approach has given rise to the formulation of two distinct groups, containing substances with similar properties, that can be addressed with limited higher tier animal testing and read across of in vivo results., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Excessive inhalation of cobalt (Co) dust can have harmful effects on the respiratory tract, yet all cobalt substances do not have the same potential for inducing toxicity. The prevalent hypothesis is that the potential of Co substances to release Co 2+ ions in the organism and in cells drives their toxicity profile. Here, we explored the possibility of grouping Co substances for predicting inhalation toxicity based on in vitro data using the stabilization of hypoxia-inducible factor (HIF)-1α as a read out for intracellular Co ion content. We evaluated the potential of 11 inorganic Co compounds and two Co metal powder samples to stabilize intracellular HIF-1α in alveolar epithelial cells (A549) after 24 h exposure to 250-1000 μM Co equivalents. Cytotoxic activity of the substances was assessed in parallel after 72 h at the same doses. Two groups were identified: (1) substances with high intracellular bioavailability (n=9), causing cytotoxicity and stabilizing HIF-1α and (2) substances with low intracellular bioavailability (n = 4), and not inducing these effects. This study provides a link between screening-level data (solubility in artificial lung fluids, Tier 1) and hypothesized biological key events., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

In vitro studies have shown that cobalt substances predominantly induce pre-inflammatory biomarkers, resulting in a grouping of substances either predicted to cause inflammation following inhalation, or those with a different reactivity profile (poorly-reactive). There is a lack of data on whole-organ lung responses following inhalation of these substances, especially relating to the poorly-reactive group. It is of interest to generate tissue-specific histopathological correlation to better ascertain the predictive nature of the lower tier tests (i.e. tier 1 - bioelution, tiers 2a and b - in vitro markers and ToxTracker testing), in order to understand the type of effects caused by the poorly-reactive group and to gauge long-term effects. Eight cobalt substances were tested in vivo in a customized 4-h toxicity test; with animals sacrificed up to 14-days post-exposure. Histopathological severity scores were assigned based on inflammatory and pre-carcinogenic markers. A clear pattern emerged, with the reactive substances causing a persistent increase in one or more of the selected markers, and absence of these markers with poorly-reactive substances. Longer-term studies should be conducted to investigate the repeated dose effects of the poorly-reactive substances., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Lung cancer following inhalation in rodents is a major concern regarding exposure to cobalt substances. However, little information is available on adverse effects and toxicity following long-term inhalation exposure to poorly soluble cobalt substances with low bioavailability. Thus, the present study focused on pulmonary effects of the poorly soluble tricobalt tetraoxide (5, 20, 80 mg/m³) in a 28-day inhalation exposure study. Lung weights increased with increasing exposures. Bronchoalveolar lavage fluid analysis and histopathology revealed lung tissue inflammation at the mid-dose with increasing severity in the high-dose group and post-exposure persistency. Markers for cellular damage and cell proliferation were statistically significantly increased. No increase in 8-OH-dG lesions was observed, indicating an absence of oxidative DNA lesions. The primary effect of inhaled Co 3 O 4 particles is inflammation of the respiratory tract strongly resembling responses of inhaled "inert dust" substances, with a NOAEC of 5 mg/m³ under the conditions of this test., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Cobalt is an environmental toxicant that is known to damage human health. However, the molecular mechanisms underlying cobalt-induced neurotoxicity have not been elucidated in detail. In the present research, we used human neuroglioma H4 cells as an in vitro model. Cells were exposed to CoCl 2 (0, 100, 200, 400 μM) for 24 h. We performed m 6 A sequencing techniques and constructed FTO-knockdown/FTO-overexpressing cells to investigate the role of FTO-mediated m 6 A modification in regulating apoptosis following CoCl 2 induced oxidative stress. Our study has shown CoCl 2 exposure led to the decrease of demethylase FTO as well as elevated oxidative stress. However, NAC treatment could partly reverse the reduction of FTO expression as well as the degree of ROS via eliminating oxidative stress. Meanwhile, MeRIP-seq and RNA-seq further revealed the potential function m 6 A modification in regulating apoptosis. More importantly, KEGG pathway and Gene ontology (GO) analyses further elucidated that the differentially m 6 A-modified genes were aggregated in apoptosis-related pathways. Mechanistic analysis indicated that knockdown of FTO facilitated CoCl 2 -induced apoptosis via caspase activation and G1/S cell cycle arrest. Nevertheless, overexpression of FTO partly attenuated the increased apoptosis following CoCl 2 exposure. More notably, we observed that FTO regulated apoptosis in an m 6 A-dependent manner. Therefore, our findings reveal that CoCl 2 induced ROS affected the m 6 A modification of apoptosis-related genes by decreasing the expression of FTO, thereby resulting in the activation of apoptosis. These findings provide important insights into CoCl 2 -induced apoptosis and m 6 A modification and propose a novel strategy for studying environmental toxicant-related neurodegeneration., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

It has been previously reported that family history of hypertension (FHH) and exposure to metals are each independent risk factor for hypertension, but the interaction between the two in relation to hypertension risk has been poorly studied. The object of this study is Dong ethnic group in Guizhou, China. The impacts of exposure to metals and FHH on hypertension incidence were examined by using the restrictive cubic spline (RCS) model as well as the multivariate logistic regression model. As a result, FHH, together with cobalt and lead exposure, was identified to show independent significant correlation with hypertension incidence (P < 0.05). The risk of hypertension increased with the increase in lead and cobalt exposure quartiles. Typically, the RCS model revealed such dose-response relation. To further confirm the association of cobalt, lead, and FHH with the risk of hypertension, multiplication and addition models were used to analyze the influence of the interactions between these variables on the risk of hypertension. The results showed that there was a multiplying interaction between the influence of the FHH and cobalt on the risk of hypertension. As for the additive interaction between cobalt and FHH, the relative excess risk due to interaction (RERI) was determined to be 0.596 (95% Cl: 0.001-1.191), the attributable proportion due to interaction (AP) was calculated as 0.256 (95% Cl: 0.075-0.437), whereas the synergy index (S) was identified to be 1.814 (95% Cl: 1.080-3.047). Our study provides some limited evidence that a FHH and cobalt exposure synergistically promote the prevalence of hypertension., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

A new chemosensor 1 was synthesized by reacting rhodamine B hydrazide and 2,3,4-trihydroxybenzaldehyde, which was then characterized by spectroscopic techniques and single crystal X-ray crystallography. Sensor 1 has the ability to sense Co 2+ /Cu 2+ ions by "naked-eye" with an apparent colour change from colourless to pink in different solvent system, MeCN and DMF respectively. Furthermore, it can selectively detect Co 2+ /Cu 2+ among wide range of different metal ions, and it exhibits low detection limit of 4.425 × 10 -8 M and 1.398 × 10 -7 M respectively. Binding mode of the two complexes were determined to be 1:1 stoichiometry for Co 2+ complex and 1:2 stoichiometry for Cu 2+ complex through Job's plot, IR spectroscopy, mass spectrometry and 1 H NMR spectroscopy. Moreover, reversibility of the sensor 1 as copper (II) ion detector was determined by using EDTA and the results showed that sensor 1 can be reused for at least 6 cycles. Other than that, a low cost chemosensor test strips were fabricated for the convenient "naked-eye" detection of Co 2+ and Cu 2+ in pure aqueous media. The MTT assay was conducted in order to determine the cytotoxicity of sensor 1 towards human cell lines., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Despite advances in stent technology for vascular interventions, in-stent restenosis (ISR) remains a main complication. The corrosion of cobalt-chromium (CoCr) alloy coronary stents has been identified to be associated with ISR, whereas its role in ISR has not been elucidated. In the current work, CoCr nanoparticles, simulated corrosion products of CoCr alloy, were used to investigate their effect on the endothelial cells. It has been demonstrated that the cell viability declines and the cell membrane is damaged, indicating the cytotoxicity of CoCr nanoparticles. The expression of GRP78, CHOP, and cleaved-caspase12 proteins has increased when exposed to CoCr nanoparticles, suggesting that CoCr nanoparticles induced cell apoptosis through endoplasmic reticulum (ER) stress-mediated apoptotic pathway. An increased release of adhesion and inflammatory mediators was also induced by CoCr nanoparticles, including ICAM-1, VCAM-1, IL-1β, IL-6, and TNF-α. Our results demonstrated that CoCr nanoparticles could trigger apoptosis, adhesion, and inflammation. These findings indicated potential damaging effects of CoCr nanoparticles on the vascular endothelium, which suggested corrosion of CoCr alloy may promote the progression and development of ISR., (© 2021 John Wiley & Sons, Ltd.)

Rodent alveolar/bronchiolar carcinomas (ABC) that arise either spontaneously or due to chemical exposure are similar to a subtype of lung adenocarcinomas in humans. B6C3F1/N mice and F344/NTac rats exposed to cobalt metal dust (CMD) by inhalation developed ABCs in a dose dependent manner. In CMD-exposed mice, the incidence of Kras mutations in ABCs was 67% with 80% of those being G to T transversions on codon 12 suggesting a role of oxidative stress in the pathogenesis. In vitro studies, such as DMPO (5,5-dimethyl-1-pyrroline N-oxide) immune-spin trapping assay, and dihydroethidium (DHE) fluorescence assay on A549 and BEAS-2B cells demonstrated increased oxidative stress due to cobalt exposure. In addition, significantly increased 8-oxo-dG adducts were demonstrated by immunohistochemistry in lungs from mice exposed to CMD for 90 days. Furthermore, transcriptomic analysis on ABCs arising spontaneously or due to chronic CMD-exposure demonstrated significant alterations in canonical pathways related to MAPK signaling (IL-8, ErbB, Integrin, and PAK pathway) and oxidative stress (PI3K/AKT and Melatonin pathway) in ABCs from CMD-exposed mice. Oxidative stress can stimulate PI3K/AKT and MAPK signaling pathways. Nox4 was significantly upregulated only in CMD-exposed ABCs and NOX4 activation of PI3K/AKT can lead to increased ROS levels in human cancer cells. The gene encoding Ereg was markedly up-regulated in CMD-exposed mice. Oncogenic KRAS mutations have been shown to induce EREG overexpression. Collectively, all these data suggest that oxidative stress plays a significant role in CMD-induced pulmonary carcinogenesis in rodents and these findings may also be relevant in the context of human lung cancers., (© 2021. This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.)

Aims: This paper aims to quantify the growth and organic acid production of Aspergillus niger, Penicillium chrysogenum and Penicillium simplicissimum when these fungi are exposed to varying levels of lithium (Li) and cobalt (Co). The study also tests whether pre-exposing the fungi to these metals enables the fungi to develop tolerance to Li or Co., Methods and Results: When cultures of A. niger, P. chrysogenum or P. simplicissimum were exposed to 250 mg l -1 of Li or Co, biomass production and excretion of organic acids were significantly inhibited after 5 days of growth compared to cultures grown in the absence of these metals. Pre-exposing cultures of A. niger to 250 mg l -1 of Li or Co for 20 days significantly increased biomass production when the fungus was subsequently sub-cultured into 250 or 500 mg l -1 of Li or Co. However, pre-exposure of P. chrysogenum or P. simplicissimum to 250 mg l -1 of Li or Co for 20 days did not increase biomass production., Conclusions: Aspergillus niger, but not the Penicillium species, developed tolerance to Li and to Co during the 20-day pre-exposure period. Therefore, processes that utilize fungal bioleaching with A. niger to mobilize and recover valuable metals such as Li or Co should consider a pre-exposure step for fungi to improve their tolerance to metal toxicity., Significance and Impact of the Study: Fungi may have the ability to extract valuable metals such as Li and Co from spent rechargeable batteries. However, the toxicity of the extracted metals can inhibit fungal growth and organic acid production. Pre-exposure to metals may alleviate toxicity for some fungal species. This knowledge can be used to improve the design of bioleaching protocols, increasing the potential for fungal bioleaching to become an economical and environmentally friendly method of recovering Li and Co from spent batteries., (© 2020 The Society for Applied Microbiology.)

Choriocarcinoma cells BeWo b30 are used to model human placental trophoblast hypoxia using cobalt (II) chloride and hydroxyquinoline derivative (HD) as chemical inducers of hypoxia-inducible factor (HIF). In this study, it was shown that both substances activate the hypoxic pathway and the epithelial-mesenchymal transition and inhibit the pathways of cell proliferation. However, CoCl 2 caused activation of the apoptosis pathway, increased the activity of effector caspases 3 and 7, and increased the expression of the unfolded protein response target DDIT3. The mTORC1 pathway was activated upon exposition to CoCl 2 , while HD suppressed this pathway, as it happens during real trophoblast hypoxia. Thus, effect of CoCl 2 on BeWo cells can be a model of severe hypoxia with activation of apoptosis, while HD mimics moderate hypoxia., (© 2021. The Author(s).)

Cobalt (Co) is an essential element with human exposure occurring from the diet, supplement ingestion, occupational sources, and medical devices. The European Chemical Agency (ECHA) recently voted to classify Co metal as a Reproductive Hazard Category 1B; presumed human reproductive toxicant due to adverse testicular effects in male rodents. A weight of evidence evaluation of the preclinical reproductive and developmental toxicity studies and available clinical data was performed to critically evaluate the relevance of this proposed classification for Co in medical devices. Reproductive responses to Co are limited to the male testes and sperm function following high systemic exposure in rodents, only at Co concentrations/doses that result in overt toxicity (i.e., above the maximum tolerable dose (MTD)). The potential mechanisms of Co reproductive/developmental toxicity, including its indirect mode of action in the testes and relevance to humans, are discussed. The available preclinical and clincial evidence suggests that it would be more appropriate to classify Co as a Reproductive Hazard Category 2 compound: suspected human reproductive toxicant and, in the case of Co-containing medical devices, it should not be considered a reproductive hazard., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Primary cilia are microtubule-based organelles that are involved in sensing micro-environmental cues and regulating cellular homeostasis via triggering signaling cascades. Hypoxia is one of the most common environmental stresses that organ and tissue cells may often encounter during embryogenesis, cell differentiation, infection, inflammation, injury, cerebral and cardiac ischemia, or tumorigenesis. Although hypoxia has been reported to promote or inhibit primary ciliogenesis in different tissues or cultured cell lines, the role of hypoxia in ciliogenesis is controversial and still unclear. Here we investigated the primary cilia change under cobalt chloride (CoCl 2 )-simulated hypoxia in immortalized human retina pigment epithelial-1 (hTERT RPE-1) cells. We found CoCl 2 treatment elongated primary cilia in a time- and dose-dependent manner. The prolonged cilia recovered back to near normal length when CoCl 2 was washed out from the cell culture medium. Under CoCl 2 -simulated hypoxia, the protein expression levels of HIF-1/2α and acetylated-α-tubulin (cilia marker) were increased, while the protein expression level of Rabaptin-5 is decreased during hypoxia. Taken together, our results suggest that hypoxia may elongate primary cilia by downregulating Rabaptin-5 involved endocytosis. The coordination between endocytosis and ciliogenesis may be utilized by cells to adapt to hypoxia., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

As the use of engineered nanomaterials increases, so does the risk of them spreading to natural ecosystems. Hitherto, knowledge regarding the toxic properties of nanoparticles (NP's) and their potential interactions with natural bio-organic molecules adsorbed to them, and thereby forming surface coronas, is limited. However, we show here that the toxic effect of NPs of tungsten carbide cobalt (WC-Co) and cobalt (Co) on the crustacean Daphnia magna is postponed in the presence of natural biological degradation products (eco-corona biomolecules). For Daphnia exposed to WC-Co NPs the survival time increased with 20-25% and for Co NPs with 30-47% after mixing the particles with a solution of eco-corona biomolecules before exposure. This suggests that an eco-corona, composed of biomolecules always present in natural ecosystems, reduces the toxic potency of both studied NPs. Further, the eco-coronas did not affect the particle uptake, suggesting that the reduction in toxicity was related to the particle-organism interaction after eco-corona formation. In a broader context, this implies that although the increasing use and production of NPs may constitute a novel, global environmental threat, the acute toxicity and long-term effects of some NPs will, at least under certain conditions, be reduced as they enter natural ecosystems.

Fermented soybean products have attracted great attention due to their health benefits. In the present study, the hypoxia-injured PC12 cells induced by cobalt chloride (CoCl 2 ) were used to evaluate the neuroprotective potency of tofu fermented by Actinomucor elegans (FT). Results indicated that FT exhibited higher phenolic content and antioxidant activity than tofu. Moreover, most soybean isoflavone glycosides were hydrolyzed into their corresponding aglycones during fermentation. FT demonstrated a significant protective effect on PC12 cells against hypoxic injury by maintaining cell viability, reducing lactic dehydrogenase leakage, and inhibiting oxidative stress. The cell apoptosis was significantly attenuated by the FT through down-regulation of caspase-3, caspases-8, caspase-9, and Bax, and up-regulation of Bcl-2 and Bcl-xL. S-phase cell arrest was significantly inhibited by the FT through increasing cyclin A and decreasing the p21 protein level. Furthermore, treatment with the FT activated autophagy, indicating that autophagy possibly acted as a survival mechanism against CoCl 2 -induced injury. Overall, FT offered a potential protective effect on nerve cells in vitro against hypoxic damage.

Systemic cobalt (Co) and chromium (Cr) concentrations may be elevated in patients with metal joint replacement prostheses. Several studies have highlighted the detrimental effects of this exposure on bone cells in vitro, but the underlying mechanisms remain unclear. In this study, we use whole-genome microarrays to comprehensively assess gene expression in primary human osteoblasts, osteoclast precursors and mature resorbing osteoclasts following exposure to clinically relevant circulating versus local periprosthetic tissue concentrations of Co 2+ and Cr 3+ ions and CoCr nanoparticles. We also describe the gene expression response in osteoblasts on routinely used prosthesis surfaces in the presence of metal exposure. Our results suggest that systemic levels of metal exposure have no effect on osteoblasts, and primarily inhibit osteoclast differentiation and function via altering the focal adhesion and extracellular matrix interaction pathways. In contrast, periprosthetic levels of metal exposure inhibit both osteoblast and osteoclast activity by altering HIF-1α signaling and endocytic/cytoskeletal genes respectively, as well as increasing inflammatory signaling with mechanistic implications for adverse reactions to metal debris. Furthermore, we identify gene clusters and KEGG pathways for which the expression correlates with increasing Co 2+ :Cr 3+ concentrations, and has the potential to serve as early markers of metal toxicity. Finally, our study provides a molecular basis for the improved clinical outcomes for hydroxyapatite-coated prostheses that elicit a pro-survival osteogenic gene signature compared to grit-blasted and plasma-sprayed titanium-coated surfaces in the presence of metal exposure.

Hard metal lung disease (HMLD) is rarely diagnosed and is caused by the occupational inhalation of hard metal dust, mainly cobalt. The diagnosis of HMLD is based on a thorough occupational dust exposure combined with clinical-radiological-histological findings. We present a series of four Chinese workers who had occupational exposure to cobalt acid lithium or cobalt and tungsten dust. Four patients all complained of intermittent cough, chest tightness, or shortness of breath on exertion. High-resolution computed tomography scans presented bilateral ground-glass attenuation, consolidations, and/or reticular opacities with diffuse small nodules. Histologic findings showed that interstitial inflammation and fibrotic lesions distributed peribronchioles. The infiltrations by macrophages as well as visible multinucleated giant cells indicated giant cell interstitial pneumonia (GIP). Cobalt was detectable in the lung tissues of two patients measured by inductively-coupled plasma mass spectrometry. The first patient was diagnosed with cobalt-related interstitial lung disease (ILD), while the others were HMLD. GIP is the classic pathology of cobalt-related ILD or HMLD. One of the patients showed spontaneous remission after the cessation of exposure, while the other three recovered within 6-32 weeks after avoiding occupational exposure and using corticosteroids. At follow-up, all four patients showed no recurrence. A multidisciplinary diagnostic panel including occupational cobalt exposure evaluation is beneficial to recognize cobalt-related ILD or HMLD and to indicate the necessity of prevention.

Hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) can differentiate into all blood lineages to maintain hematopoiesis, wound healing, and immune functions. Recently, cobalt-chromium alloy casting implants have been used extensively in total hip replacements; however, cobalt nanoparticles (CoNPs) released from the alloy were toxic to HSCs and HPCs. We aimed to investigate the mechanism underlying the toxic effect of CoNPs on HSCs/HPCs and to determine the protective effect of selenomethionine (SeMet) against CoNPs in vitro and in vivo . Human and rat CD34+ HSCs/HPCs were isolated from cord blood and bone marrow, respectively. CoNPs decreased the viability of CD34+ HSCs/HPCs and increased apoptosis. SeMet attenuated the toxicity of CoNPs by enhancing the antioxidant ability of cells. The protective effect of SeMet was not completely abolished after adding H2O2 to abrogate the improvement of the antioxidant capacity by SeMet. SeMet and CoNPs stimulated ATM/ATR DNA damage response signals and inhibited cell proliferation. Unlike CoNPs, SeMet did not damage the DNA, and cell proliferation recovered after removing SeMet. SeMet inhibited the CoNP-induced upregulation of hypoxia inducible factor (HIF)-1α, thereby disrupting the inhibitory effect of HIF-1α on breast cancer type 1 susceptibility protein (BRCA1). Moreover, SeMet promoted BRCA1-mediated ubiquitination of cyclin B by upregulating UBE2K. Thus, SeMet enhanced cell cycle arrest and DNA repair post-CoNP exposure. Overall, SeMet protected CD34+ HSCs/HPCs against CoNPs by stimulating antioxidant activity and DNA repair.

In the present study, protective effects of Ananas comosus i.e., pineapple pulp (PA) against cobalt chloride (CoCl 2 )‑induced hypoxia in Caco-2 cells were evaluated. PA reduces levels of lipid peroxidation, reactive oxygen and nitrogen species. It was proved to be cytoprotective and increased anti-oxidant activity against CoCl 2 -induced hypoxia. The inference drawn from this experiment was CoCl 2 -induced hypoxia that regulates hypoxia-inducible factor-1 (HIF-1), a transcription factor. It was also confirmed that PA pre-treatment inhibited the expression of HIF-1α, thereby downregulating the hypoxia-associated gene/protein expressions such as GLUT-1, VEGF, ANG and FGF. Finally, supplementation of PA could help in snow-balling the digestive hormones like leptin and CCK in hypoxic conditions. Therefore, this report provides substantial proof of reducing the hypoxia-induced loss of appetite at high-altitude environments. Graphical Abstract.