Nickel Carcinogenesis Mechanism: DNA Damage

To breathe or not to breathe: Inhalational exposure to heavy metals and related health risk

This study reviewed scientific literature on inhalation exposure to heavy metals (HMs) in various indoor and outdoor environments and related carcinogenic and non-carcinogenic risk. A systematic search in Web of Science, Scopus, PubMed, Embase, and Medline databases yielded 712 results and 43 articles met the requirements of the Population, Exposure, Comparator, and Outcomes (PECO) criteria. Results revealed that HM concentrations in most households exceeded the World Health Organization (WHO) guideline values, indicating moderate pollution and dominant anthropogenic emission sources of HMs. In the analyzed schools, universities, and offices low to moderate levels of air pollution with HMs were revealed, while in commercial environments high levels of air pollution were stated. The non-carcinogenic risk due to inhalation HM exposure exceeded the acceptable level of 1 in households, cafes, hospitals, restaurants, and metros. The carcinogenic risk for As and Cr in households, for Cd, Cr, Ni, As, and Co in educational environments, for Pb, Cd, Cr, and Co in offices and commercial environments, and for Ni in metros exceeded the acceptable level of 1 × 10-4. Carcinogenic risk was revealed to be higher indoors than outdoors. This review advocates for fast and effective actions to reduce HM exposure for safer breathing.

Nickel Induces Pyroptosis via the Nrf2/NLRP3 Pathway in Kidney of Mice

Nickel (Ni) is considered a toxic metal, and excessive exposure can cause kidney damage. This study was designed to explore whether nickel chloride (NiCl2) can induce cell pyroptosis and its possible mechanism. Here, we found that NiCl2 treatment could reduce the kidney index and result in kidney damage. Meanwhile, NiCl2 could obviously induce renal pyroptosis, which was characterized by an increase in IL-18, IL-1β, NLRP3, and GSDMD expression. Furthermore, NiCl2 induced pyroptosis through the Nrf2/NLRP3 pathway which featured down-regulated protein and mRNA expression levels of Nrf2 and up-regulated protein and mRNA expression levels of Caspase-1, NLRP3, and GSDMD. In summary, excessive Ni exposure can induce renal cell pyroptosis, ultimately leading to kidney tissue damage and hindering normal development, and its possible mechanism may be due to the inhibition of the Nrf2 pathway.

Contamination of trace, non-essential/heavy metals in nutraceuticals/dietary supplements: A chemometric modelling approach and evaluation of human health risk upon dietary exposure

Across the world, nutraceuticals/dietary supplements are commonly consumed without medical supervision, and believing these products are harmless to health. However, these products may contain trace (TMs) and non-essential/heavy metals (nHMs) as contaminants at levels higher than the recommended daily allowance (RDA), which can be hazardous to human health. Consequently, it is crucial to assess the levels of these metals to ensure the safety of these products. This study aimed to analyze the concentration of TMs (Mn, Cu and Zn) and nHMs (Al, Cr, Ni, Cd and Pb) in nutraceuticals/dietary supplements. Metal analysis was conducted using inductively coupled plasma-optical emission spectrometry (ICP-OES). Multivariate and bivariate analysis including principle component analysis (PCA), hierarchical cluster analysis (HCA) and Pearson correlation coefficient (PCC) were applied to understand inter-metal association and sources of these metals. Concentration ranges for TMs were found as, Mn (0.2-4.3 mg/kg), Cu (0.11-2.54 mg/kg), and Zn (0.1-22.66 mg/kg) while the nHMs concentration ranges were: Al (0.046-3.336 mg/kg), Cr (0.11-1.63 mg/kg), Ni (0.18-0.72 mg/kg), Cd (0.04-0.92 mg/kg), and Pb (0.18-1.08 mg/kg). The levels of tolerable dietary intake (TDI) for Cr and Ni, and the provisional tolerable monthly intake (PTMI) limit for Cd, exceeded the values set by the World Health Organization (WHO) and the European Food Safety Authority (EFSA). The estimation of the target hazard quotient (THQ <1), hazard index (HI < 1) and cumulative cancer risk (CCR <1 ✕ 10-3) indicated no significant non-carcinogenic and carcinogenic health risks associated with consuming these products. Therefore, the primary recommendation from this study is to use the nutraceuticals/dietary supplements should be under the supervision of dietitian.

Nickel induces epithelial-mesenchymal transition in pulmonary fibrosis in mice via activation of the oxidative stress-mediated TGF-β1/Smad signaling pathway

Nickel (Ni) is recognized as a carcinogenic metal, and its widespread use has led to severe environmental and health problems. Although the lung is among the main organs affected by Ni, the precise mechanisms behind this effect remain poorly understood. This study aimed to elucidate the physiological mechanisms underlying Ni-induced pulmonary fibrosis (PF), using various techniques including histopathological detection, biochemical analysis, immunohistochemistry, western blotting, and quantitative real-time PCR. Mice were treated with nickel chloride (NiCl2), which induced PF (detected by Masson staining), up-regulation of α-smooth muscle actin (α-SMA), and collagen-1 mRNA and protein expression. NiCl2 was found to induce PF by: activation of the epithelial-mesenchymal transition (EMT) and the transforming growth factor-β1 (TGF-β1)/Smad signaling pathway; up-regulation of protein and mRNA expression of TGF-β1, p-Smad2, p-Smad3, vimentin, and N-cadherin; and down-regulation of protein and mRNA expression of E-cadherin. In addition, NiCl2 treatment increased malondialdehyde content while inhibiting antioxidant activity, as indicated by decreased catalase, total antioxidant capacity, and superoxide dismutase activities, and glutathione content. Co-treatment with the effective antioxidant and free radical scavenger N-acetyl cysteine (NAC) plus NiCl2 was used to study the effects of oxidative stress in NiCl2-induced PF. The addition of NAC significantly mitigated NiCl2-induced PF, and reversed activation of the TGF-β1/Smad signaling pathway and EMT. NiCl2-induced PF was therefore shown to be due to EMT activation via the TGF-β1/Smad signaling pathway, mediated by oxidative stress.

Comparison of trace elements in peripheral blood and bone marrow of newly diagnosed multiple myeloma patients

Trace elements are essential micronutrients for the human body. Their roles are indispensable, as they are involved in a wide range of vital biological processes. In this study, we aimed to evaluate alterations in trace elements in the blood and bone marrow serum of patients with newly diagnosed multiple myeloma (NMM). The levels of zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), magnesium (Mg), selenium (Se), arsenic (As), boron (B), nickel (Ni), silicon (Si) and chromium (Cr) were analyzed in the venous blood samples of the patient group comprising 70 patients with NMM (41 males and 29 females) and compared to those in the control group comprising 30 individuals (18 males and 12 females). In addition, trace element levels were analyzed in bone marrow samples from the patient group. Blood and bone marrow serum levels were quantified using inductively coupled plasma optical emission spectrometry. When the blood samples of the patient and control groups were compared: Zn (p = 0.011), Fe (p = 0.008), Mn (p = 0.046), Se (p < 0.001), As (p < 0.001), Ni (p < 0.001) and Cr (p < 0.001) levels were significantly higher in the patient group than in the control group. Higher Zn, Fe, Mn, Se, As, Ni and Cr levels in the NMM patients suggest that alterations of trace elements could be predisposing factor that initiates the malignant process. The relationship between malignancies and trace elements is crucial for the development of adjuvant therapy strategies and preventive medicine and as biomarkers for cancer diagnosis. Therefore, there is a need for studies examining the relationship between hematological malignancies and trace elements.

Molecular Regulatory Mechanism of Nano-Se Against Copper-Induced Spermatogenesis Disorder

Selenium nanoparticle (Nano-Se) is a new type of selenium supplement, which can improve the deficiency of traditional selenium supplements and maintain its physiological activity. Due to industrial pollution and irrational use in agriculture, Cu overexposure often occurs in animals and humans. In this study, Nano-Se alleviated CuSO4-induced testicular Cu accumulation, serum testosterone level decrease, testicular structural damage, and decrease in sperm quality. Meanwhile, Nano-Se reduced the ROS content in mice testis and enhanced the activities of T-AOC, GSH, SOD, and CAT compared with CuSO4 group. Furthermore, Nano-Se alleviated CuSO4-induced apoptosis by increasing the protein expression of Cleaved-Caspase-3, Cleaved-Caspase-9, Cleaved-Caspase-12, and Bax/Bcl-2 compared with CuSO4 group. At the same time, Nano-Se reversed CuSO4-induced increase of γ-H2AX protein expression in mice testis. In conclusion, this study confirmed that Nano-Se could alleviate oxidative stress, apoptosis, and DNA damage in the testis of mice with Cu excess, thereby protecting the spermatogenesis disorder induced by Cu.

Urinary cadmium concentration is associated with the severity and clinical outcomes of COVID-19: a bicenter observational cohort study

BACKGROUND

Cadmium and nickel exposure can cause oxidative stress, induce inflammation, inhibit immune function, and therefore has significant impacts on the pathogenesis and severity of many diseases. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can also provoke oxidative stress and the dysregulation of inflammatory and immune responses. This study aimed to assess the potential associations of cadmium and nickel exposure with the severity and clinical outcomes of patients with coronavirus disease 2019 (COVID-19).

METHODS

We performed a retrospective, observational, bicenter cohort analysis of patients with SARS-CoV-2 infection in Taiwan between June 2022 and July 2023. Cadmium and nickel concentrations in blood and urine were measured within 3 days of the diagnosis of acute SARS-CoV-2 infection, and the severity and clinical outcomes of patients with COVID-19 were analyzed.

RESULTS

A total of 574 patients were analyzed and divided into a severe COVID-19 group (hospitalized patients) (n = 252; 43.9%), and non-severe COVID-19 group (n = 322; 56.1%). The overall in-hospital mortality rate was 11.8% (n = 68). The severe COVID-19 patients were older, had significantly more comorbidities, and significantly higher neutrophil/lymphocyte ratio, C-reactive protein, and interleukin-6 than the non-severe COVID-19 patients (all p < 0.05). Blood and urine cadmium and urine nickel concentrations were significantly higher in the severe COVID-19 patients than in the non-severe COVID-19 patients. Among the severe COVID-19 patients, those in higher urine cadmium/creatinine quartiles had a significantly higher risk of organ failure (i.e., higher APACHE II and SOFA scores), higher neutrophil/lymphocyte ratio, lower PaO2/FiO2 requiring higher invasive mechanical ventilation support, higher risk of acute respiratory distress syndrome, and higher 60-, 90-day, and all-cause hospital mortality (all p < 0.05). Multivariable logistic regression models revealed that urine cadmium/creatinine was independently associated with severe COVID-19 (adjusted OR 1.643 [95% CI 1.060-2.547], p = 0.026), and that a urine cadmium/creatinine value > 2.05 μg/g had the highest predictive value (adjusted OR 5.349, [95% CI 1.118-25.580], p = 0.036).

CONCLUSIONS

Urine cadmium concentration in the early course of COVID-19 could predict the severity and clinical outcomes of patients and was independently associated with the risk of severe COVID-19.

The mechanism of nickel-induced autophagy and its role in nephrotoxicity

Nickel (Ni), an environmental health hazard, is nephrotoxic to humans, but the exact mechanism is unknown. This study aims to identify whether nephrotoxicity is associated with autophagy. Here, nickel chloride (NiCl2) increased autophagy in TCMK-1 cells. NiCl2 induces autophagy through Akt and AMPK/mTOR pathways. Next, oxidative stress was investigated in NiCl2-induced autophagy. The findings demonstrated that the antioxidant (NAC) or mitochondrial targeted antioxidant (Mito-TEMPO) attenuated NiCl2-induced autophagy, reversed the influence on AMPK-mTOR and Akt pathways. Additionally, our study examined the role of autophagy in NiCl2-induced nephrotoxicity. Autophagy inhibition with 3-MA could inhibit cell viability and increase apoptosis in the TCMK-1 cells, however, autophagy promotion with rapamycin relieved cytotoxicity and decreased apoptosis. Additionally, co-treatment with Z-VAD-FMK reduced cytotoxicity, but did not affect autophagy. Besides, NiCl2 can increase the level of mitophagy in vivo and vitro. Mitophagy inhibition could inhibit cell viability and increase apoptosis in the TCMK-1 cells, whereas, promotion of mitophagy could increase cell viability and decrease apoptosis. In summary, above-mentioned results showed that NiCl2 induces autophagy in TCMK-1 cells through oxidative stress-dependent AMPK/AKT-mTOR pathway, autophagy plays a role in reducing NiCl2-induced renal toxicity, and a major mechanism in autophagy's inhibitory effect on NiCl2-induced apoptosis may be mitophagy.

DNA methylation aging signatures of multiple metals exposure and their mediation effects in metal-associated mortality: Evidence from the Dongfeng-Tongji cohort study

Humans were exposed to multiple metals, but the impact of metals on DNA methylation-age (DNAm-age), a well-recognized aging measure, remains inconclusive. This study included 2942 participants from the Dongfeng-Tongji cohort. We detected their plasma concentrations of 23 metals and determined their genome-wide DNA methylation using the Illumina Human-MethylationEPIC BeadChip. Five DNAm-age acceleration indexes (DAIs), including HannumAge-Accel, HorvathAge-Accel, PhenoAge-Accel, GrimAge-Accel (residual from regressing corresponding DNAm-age on chronological age) and DNAm-mortality score (DNAm-MS), were separately calculated. We found that each 1-unit increase in ln-transformed copper (Cu) was associated with a separate 1.02-, 0.83- and 0.07-unit increase in PhenoAge-Accel, GrimAge-Accel, and DNAm-MS (all FDR<0.05). Each 1-unit increase in ln-transformed nickel (Ni) was associated with a 0.34-year increase in PhenoAge-Accel, while each 1-unit increase in ln-transformed strontium (Sr) was associated with a 0.05-unit increase in DNAm-MS. The Cu, Ni and Sr showed joint positive effects on above three DAIs. PhenoAge-Accel, GrimAge-Accel, and DNAm-MS mediated a separate 6.5%, 12.3%, 6.0% of the positive association between Cu and all-cause mortality; GrimAge-Accel mediated 14.3% of the inverse association of selenium with all-cause mortality. Our findings revealed the effects of Cu, Ni, Sr and their co-exposure on accelerated aging and highlighted mediation roles of DNAm-age on metal-associated mortality.

Chronic nickel exposure alters extracellular vesicles to mediate cancer progression via sustained NUPR1 expression

Cancer cells release extracellular vesicles (EVs) that participate in altering the proximal tumor environment and distal tissues to promote cancer progression. Chronic exposure to nickel (Ni), a human group I carcinogen, results in epigenetic changes that promotes epithelial to mesenchymal transition (EMT). Cells that undergo EMT demonstrate various molecular changes, including elevated levels of the mesenchymal cadherin N-cadherin (N-CAD) and the transcription factor Zinc finger E-box binding homeobox 1 (ZEB1). Moreover, the molecular changes following EMT induce changes in cellular behavior, including anchorage-independent growth, which contributes to cancer cells detaching from tumor bulk during the metastatic process. Here, we present data demonstrating that EVs from Ni-exposed cells induce EMT in recipient BEAS-2B cells in the absence of Ni. Moreover, we show evidence that the EVs from Ni-altered cells package the transcription factor nuclear protein 1 (NUPR1), a transcription factor associated with Ni exposure and cancer progression. Moreover, our data demonstrates that the NUPR1 in the EVs becomes part of the recipient cell proteomic milieu and carry the NUPR1 to the nuclear space of the recipient cell. Interestingly, knockdown of NUPR1 in Ni-transformed cells suppressed NUPR1 packaging in the EVs, and nanoparticle tracking analysis (NTA) demonstrated decreased EV release. Reduction of NUPR1 in EVs resulted in diminished EMT capacity that resulted in decreased anchorage independent growth. This study is the first to demonstrate the role of NUPR1 in extracellular vesicle-mediate cancer progression.

The role of long noncoding RNA MEG3 in fibrosis diseases

Fibrosis is a prevalent pathological condition observed in various organs and tissues. It primarily arises from the excessive and abnormal accumulation of the extracellular matrix, resulting in the structural and functional impairment of tissues and organs, which can culminate in death. Many forms of fibrosis, including liver, cardiac, pulmonary, and renal fibrosis, are considered irreversible. Maternally expressed gene 3 (MEG3) is an imprinted RNA gene. Historically, the downregulation of MEG3 has been linked to tumor pathogenesis. However, recent studies indicate an emerging association of MEG3 with fibrotic diseases. In this review, we delve into the current understanding of MEG3's role in fibrosis, aiming to shed light on the molecular mechanisms of fibrosis and the potential of MEG3 as a novel therapeutic target.

Cyto and Genoprotective Potential of Tannic Acid Against Cadmium and Nickel Co-exposure Induced Hepato-Renal Toxicity in BALB/c Mice

Tannic acid (TA) is a metal chelating polyphenol that plays a crucial role in metal detoxification, but its modulatory role in co-exposure of these heavy metals' exposure needs to be explored. Cadmium (Cd) and nickel (Ni) are inorganic hazardous chemicals in the environment. Humans are prone to be exposed to the co-exposure of Cd and Ni, but the toxicological interactions of these metals are poorly defined. Present study was undertaken to study the preventive role of TA in Cd-Ni co-exposure-evoked hepato-renal toxicity in BALB/c mice. In the current investigation, increased oxidative stress in metal intoxicated groups was confirmed by elevated peroxidation of the lipids and significant lowering of endogenous antioxidant enzymes. Altered hepato-renal serum markers, DNA fragmentation, and histological alterations were also detected in the metal-treated groups. Present study revealed that Cd is a stronger toxicant than Ni and when co-exposure was administered, additive, sub-additive, and detrimental effects were observed. Prophylactic treatment with TA significantly reinstated the levels of lipid peroxidation (LPO), non-enzymatic, and enzymatic antioxidants. Moreover, it also restored the serum biomarker levels, DNA damage, and histoarchitecture of the given tissues. TA due to its metal chelating and anti-oxidative properties exhibited cyto- and genoprotective potential against Cd-Ni co-exposure-induced hepatic and renal injury.

Health Risks for Consumers of Forest Ground Cover Produce Contaminated with Heavy Metals

BACKGROUND

The activity of heavy metal (HM) mining and processing industries causes soils contamination with HM. The metals could be transferred from contaminated soils to edible plants and fungi. This study aimed to assess the content of Cd, Pb, Hg, As, and Ni in berries and edible mushrooms collected in the forests located near Miasteczko Slaskie zinc smelter and in the Lubliniec region, in the context of consumers' health risk.

METHODS

The ET-AAS method was used to determine the content of Cd, Pb, Ni, and As. Mercury concentration was determined using the CV-AFS method.

RESULTS

The studies showed high levels of Cd and Pb in the examined products. A statistically significant impact of the distance from the smelter on the Cd concentration in the berries was observed. Total non-cancer health risk from the combined exposure of adults to all HM in mushrooms and berries was significant when consuming the most heavily contaminated produce. The risk to children was significant, even when consuming products with moderate levels of the metals. Ingestion of Cd by children with mushrooms was related to a high cancer risk. The uncertainty of the results was determined.

CONCLUSIONS

It is recommended to take action to increase awareness among residents of the areas adjacent to the forests regarding the existing health risk and to take possible measures to reduce exposure to HM.

Exploring the molecular and toxicological mechanism associated with interactions between heavy metals and the reproductive system of Mytilus galloprovincialis

A large number of heavy metals resulted toxic to the reproductive system, but invertebrate infertility has been poorly explored, and above all, there are limited molecular, cellular and toxicological studies. In the present work, we exposed Mytilus galloprovincialis to three individual metal chlorides (CuCl2 15 μM, CdCl2 1.5 μM, NiCl2 15 μM) and their mixture for 24 h, to evaluate the effects on the protamine-like proteins (PLs), sperm DNA and on their interaction in the formation of sperm chromatin. Under all exposure conditions, but particularly after exposure to the metals mix, relevant changes in the electrophoretic pattern, by AU-PAGE and SDS-PAGE, and in fluorescence spectroscopy measurements of PLs were shown. In addition, alterations in DNA binding of these proteins were observed by Electrophoretic Mobility Shift Assay (EMSA) and through their release from sperm nuclei. Moreover, there was evidence of increased accessibility of micrococcal nuclease to sperm chromatin, which was also confirmed by toluidine blue staining. Furthermore, morphological analyses indicated severe gonadal impairments which was also corroborated by increased PARP expression, by Western blotting, and sperm DNA fragmentation, by comet assay. Finally, we investigated the expression of stress genes, gst, hsp70 and mt10, in gonadal tissue. The latter investigations also showed that exposure to this metals mix was more harmful than exposure to the individual metals tested. The present results suggest that these metals and in particular their mixture could have a negative impact on the reproductive fitness of M. galloprovincialis. Based on these evidences, we propose a molecular mechanism.

Apoptosis and DNA damage mediated by ROS involved in male reproductive toxicity in mice induced by Nickel

Nickel (Ni) is the most important environmental pollution in the world. Ni has been confirmed to have multi-organ toxicology and carcinogenicity. Recently, Ni also can impair the male reproductive system, however, its precious mechanism still has not been clarified. The current work found that nickel chloride (NiCl2) induced histopathological lesions in testis. And, the Johnsen's score, seminiferous tubule diameter, and spermatogenic epithelium thickness were decreased in NiCl2-treated mice. The number of spermatogonium, primary spermatocyte, and round spermatid also were significantly reduced after Ni treatment. Next the potential molecular mechanism was measured. NiCl2 treatment elevated ROS production in the testis. Additionally, NiCl2 was found to induce apoptosis with features including up-regulation of Bax, cleaved-caspase-3, cleaved-caspase-8, caspase-9, and caspase-12, while down-regulation of Bcl-2 expression. In the meantime, the marker protein of DNA damage γ-H2AX was significantly increased in NiCl2-primed mice testis. To clarify effects of reactive oxygen species (ROS) in apoptosis and DNA damage induced by NiCl2, NiCl2 was used to co-treat antioxidant NAC (N-Acetyl-L-cysteine). NAC weakened ROS production induced by NiCl2, and played an inhibition role in apoptosis and DNA damage. Moreover, co-treatment using NiCl2 and NAC group also eliminated spermatogenesis disorders. In summary, research results reveal the relations of spermatogenesis disorder induced by NiCl2 with apoptosis and DNA damage mediated by ROS and apoptosis in the testis.

Micronuclei frequency and exposure to chemical mixtures in three Colombian mining populations

The Colombian mining industry has witnessed significant growth. Depending on the scale and mineral extracted, complex chemical mixtures are generated, impacting the health of occupationally exposed populations and communities near mining projects. Increasing evidence suggests that chromosomal instability (CIN) is an important link between the development of certain diseases and exposure to complex mixtures. To better understand the effects of exposure to complex mixtures we performed a biomonitoring study on 407 healthy individuals from four areas: three located in municipalities exploiting different-scale mining systems and a reference area with no mining activity. Large, medium, and small-scale mining systems were analyzed in Montelibano (Córdoba), artisanal and small-scale mining (ASGM) in Nechí (Antioquia), and a closed mining system in Aranzazu (Caldas). The reference area with no mining activity was established in Montería (Córdoba). ICP-MS measured multi-elemental exposure in hair, and CIN was evaluated using the cytokinesis-block micronucleus technique (MNBN). Exposure to mixtures of chemical elements was comparable in workers and residents of the mining areas but significantly higher compared to reference individuals. In Montelibano, increased MNBN frequencies were associated with combined exposure to Se, Hg, Mn, Pb, and Mg. This distinct pattern significantly differed from other areas. Specifically, in Nechí, Cr, Ni, Hg, Se, and Mg emerged as the primary contributors to elevated frequencies of MNBN. In contrast, a combination of Hg and Ni played a role in increasing MNBN in Aranzazu. Interestingly, Se consistently correlated with increased MNBN frequencies across all active mining areas. Chemical elements in Montelibano exhibit a broader range compared to other mining zones, reflecting the characteristics of the high-impact and large-scale mining in the area. This research provides valuable insights into the effects of exposure to chemical mixtures, underscoring the importance of employing this approach in the risk assessment of communities, especially those from residential areas.

Nickel induces blood-testis barrier damage through ROS-mediated p38 MAPK pathways in mice

Nickel (Ni) is an essential common environmental contaminant, it is hazardous to male reproduction, but the precise mechanisms are still unknown. Blood-testis barrier (BTB), an important testicular structure consisting of connections between sertoli cells, is the target of reproductive toxicity caused by many environmental toxins. In this study, ultrastructure observation and BTB integrity assay results indicated that NiCl2 induced BTB damage. Meanwhile, BTB-related proteins including the tight junction (TJ), adhesion junction (AJ) and the gap junction (GJ) protein expression in mouse testes as well as in sertoli cells (TM4) were significantly decreased after NiCl2 treatment. Next, the antioxidant N-acetylcysteine (NAC) was co-treated with NiCl2 to study the function of oxidative stress in NiCl2-mediated BTB deterioration. The results showed that NAC attenuated testicular histopathological damage, and the expression of BTB-related proteins were markedly reversed by NAC co-treatment in vitro and vivo. Otherwise, NiCl2 activated the p38 MAPK signaling pathway. And, NAC co-treatment could significantly inhibit p38 activation induced by NiCl2 in TM4 cells. Furthermore, in order to confirm the role of the p38 MAPK signaling pathway in NiCl2-induced BTB impairment, a p38 inhibitor (SB203580) was co-treated with NiCl2 in TM4 cells, and p38 MAPK signaling inhibition significantly restored BTB damage induced by NiCl2 in TM4 cells. These results suggest that NiCl2 treatment destroys the BTB, in which the oxidative stress-mediated p38 MAPK signaling pathway plays a vital role.

DNA fragmentation, chromosomal aberrations, and multi-toxic effects induced by nickel and the modulation of Ni-induced damage by pomegranate seed extract in Allium cepa L

This study was designed to assess the recovery effect of pomegranate seed extract (PSEx) against nickel (Ni)-induced damage in Allium cepa. Except for the control group treated with tap water, five experimental groups were exposed to 265 mg L-1 PSEx, 530 mg L-1 PSEx, 1 mg L-1 NiCI2, 265 mg L-1 PSEx + 1 mg L-1 NiCI2, and 530 mg L-1 PSEx + 1 mg L-1 NiCI2, respectively. The toxicity of Ni was examined through the analysis of physiological (germination percentage, weight gain, and root length), cytotoxicity (mitotic index), genotoxicity (micronucleus, chromosomal anomalies, and Comet test), and biochemical (malondialdehyde, proline, chlorophyll a and chlorophyll b contents, the activities of superoxide dismutase and catalase) parameters. Meristematic cell defects were also investigated. The NiCl2-DNA interaction was evaluated through spectral shift analysis. Values of all physiological parameters, mitotic index scores, and chlorophyll contents decreased while micronucleus frequency, DNA tail percentage, chromosomal anomalies, proline, MDA, and enzyme activities increased following Ni administration. According to the tail DNA percentage scale, Ni application caused "high damage" to DNA. Ni-induced chromosomal anomalies were fragment, sticky chromosome, vagrant chromosome, bridge, unbalanced chromatin distribution, reverse polarization, and nucleus with bud. NiCl2-DNA interaction caused a hyperchromic shift in the UV/Vis spectrum of DNA by spectral profile analysis. Ni exposure impaired root meristems as evidenced by the formation of epidermis cell damage, flattened cell nucleus, thickened cortex cell wall, and blurry vascular tissue. Substantial recovery was seen in all parameters with the co-administration of PSEx and Ni. Recovery effects in the parameters were 18-51% and 41-84% in the 265 mg L-1 PSEx + 1 mg L-1 NiCI2 and 530 mg L-1 PSEx + 1 mg L-1 NiCI2 groups, respectively. The Comet scale showed that PSEx applied with Ni reduced DNA damage from "high" to "moderate." Ni-induced thickened cortex cell wall and blurry vascular tissue damage disappeared completely when 530 mg L-1 PSEx was mixed with Ni. PSEx successfully reduced the negative effects of Ni, which can be attributed to its content of antioxidants and bioactive ingredients.

Short-term exposure to multiple metals mixture and mitochondrial DNA copy number among children: A panel study

BACKGROUND

Little is known regarding the individual and overall associations of short-term co-exposure to metals mixture with mitochondrial DNA copy number (mtDNAcn) among healthy children.

METHODS

We conducted a panel study across three seasons among 144 children aged 4 to 12 years in Guangzhou. For each season, we collected the first-morning urine for four consecutive days and fasting blood on the 4th day to detect 23 urinary metals and blood leukocyte mtDNAcn, respectively. Linear mixed-effect (LME) models and multiple informant models were used to examine the relations of individual metals with mtDNAcn over different lag days, and the least absolute shrinkage and selection operator (LASSO) regression was applied to determine the most important metal. We further employed weighted quantile sum (WQS) regression to investigate the overall association of metals mixture with mtDNAcn.

RESULTS

Nickel (Ni), manganese (Mn) and antimony (Sb) were independently associated with mtDNAcn in a linear dose-response manner. Each 1-fold increase in Ni at lag 0 day, Mn and Sb at lag 2 day was associated with respective decrements of 8.74 %, 6.93 % and 3.98 % in mtDNAcn in multi-metal LME models. LASSO regression also selected Ni, Mn and Sb as the most significant metals at the corresponding lag day. WQS regression showed overall inverse associations between metals mixture and mtDNAcn both at lag 0 and lag 2 day, with mtDNAcn decreased by 2.75 % and 3.14 % in response to a quartile increase in the WQS index. Additionally, the associations of Ni and Mn with decreased mtDNAcn were stronger among children younger than 7 years, girls and those having less vegetables and fruit intake.

CONCLUSION

We found an overall association between metals mixture and decreased mtDNAcn among healthy children, in which Ni, Mn and Sb were the major contributors. Younger children, girls and those with less vegetables and fruit intake were more susceptible.

The genotoxicity impact of heavy metals on the Escherichia coli

In present work, the genotoxicity of Hg2+, Ag+, Cr6+, Ni2+, Pb2+, Co2+, Mn2+, Zn2+, and Cr3+ was investigated via a quantitative toxicogenomics assay, to understand the toxic mechanism of heavy metals with greater depth. Under the experimental conditions, Hg2+, Ag+, and Cr6+ showed a more serious toxic impact on the expression of functional genes (eg., oxyR, katG, grxA, osmE, emrE, dinG) than Ni2+, Pb2+, Co2+, Mn2+, Zn2+, and Cr3+, while the protein, oxidative, and membrane stress response pathways were more sensitive to the toxicity of Hg2+, Ag+, and Cr6+ than the DNA and general stress response pathways. Compared with the other kinds of heavy metals, Ni2+, Pb2+, Co2+, and Mn2+ altered the expression of functional genes (uvrY, recX, mutY, and sbmC) related to the DNA stress response pathways more seriously, while Zn2+ and Cr3+ changed the expression of the functional genes (yfjG, ydgL, ssrA, and osmC) associated with the general stress response pathway more significantly. Meanwhile, the toxicity of Ni2+, Pb2+, Co2+, and Mn2+ was slightly higher than that of Zn2+ and Cr3+ in terms of the total value of transcriptional effect level Index (TELI) by detecting the promoter activities of different functional genes. In addition, to survive the toxicity of heavy metals, the expression of multidrug efflux genes (ydgL, cyoA, emrA, and emrE) and toxicity-resistant genes (Ion, dnaJ, clpB, mutY, dnaK, rpoD, sbmC) mainly functioned.

Impact of mobile phone-specific electromagnetic fields on DNA damage caused by occupationally relevant exposures: results of ex vivo experiments with peripheral blood mononuclear cells from different demographic groups

The aim of this study was to investigate if age and body mass of humans have an impact on the DNA-damaging properties of high-frequency mobile phone-specific electromagnetic fields (HF-EMF, 1950 MHz, universal mobile telecommunications system, UMTS signal) and if this form of radiation has an impact on the genotoxic effects of occupationally relevant exposures. Pooled peripheral blood mononuclear cells (PBMC) from three groups [young normal weight, young obese (YO), and older age normal weight individuals] were exposed to different doses of HF-EMF (0.25, 0.5, and 1.0 W/kg specific absorption rate-SAR) and simultaneously or sequentially to different chemicals which cause DNA damage (CrO3, NiCl2, benzo[a]pyrene diol epoxide-BPDE, and 4-nitroquinoline 1-oxide-4NQO) via different molecular mechanisms. We found no difference in regard to the background values in the three groups but a significant increase of DNA damage (81% without and 36% with serum) in cells from old participants after radiation with 1.0 W/kg SAR 16 h. In combined treatment experiments we found no impact of the UMTS signal on chemically induced DNA damage in the different groups in general. However, a moderate decrease of DNA damage was seen in simultaneous treatment experiments with BPDE and 1.0 W/kg SAR in the YO group (decline 18%). Taken together our findings indicate that HF-EMF cause DNA damage in PBMC from older subjects (69.1 years). Furthermore, they show that the radiation does not increase induction of DNA damage by occupationally relevant chemicals.

Effect of exogenous taurine on growth, oxidative defense, and nickel (Ni) uptake in canola (Brassica napus L.) under Ni stress

Nickel (Ni) contamination and its associated hazardous effects on human health and plant growth are ironclad. However, the potential remedial effects of taurine (TAU) on Ni-induced stress in plants remain obscure. Therefore, the present study was undertaken to examine the effect of TAU seed priming (100 and 150 mg L‒1) as an alleviative strategy to circumvent the phytotoxic effects of Ni (150 mg kg‒1) on two canola cultivars (Ni-tolerant cv. Shiralee and Ni-sensitive cv. Dunkeld). Our results manifested an apparent decline in growth, biomass, photosynthetic pigments, leaf relative water content, DPPH free radical scavenging activity, total soluble proteins, nitrate reductase activity, and nutrient acquisition (N, P, K, Ca) under Ni toxicity. Further, Ni toxicity led to a substantial increase in oxidative stress reflected as higher levels of superoxide radicals (O2•‒) and hydrogen peroxide (H2O2) alongside increased relative membrane permeability, lipoxygenase (LOX) activity, and Ni accumulation in leaves and roots. However, TAU protected canola plants from Ni-induced oxidative damage through the amplification of hydrogen sulfide (H2S) production that intensified the antioxidant system to avert O2•‒, H2O2, and malondialdehyde (MDA) production. Further, TAU-mediated increase in H2S levels maintained membrane integrity that might have improved ionomics and bettered plant growth under Ni toxicity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01359-9.

Nickel Nanoparticles Induced Hepatotoxicity in Mice via Lipid-Metabolism-Dysfunction-Regulated Inflammatory Injury

Nickel nanoparticles (NiNPs) have wide applications in industry and biomedicine due to their unique characteristics. The liver is the major organ responsible for nutrient metabolism, exogenous substance detoxification and biotransformation of medicines containing nanoparticles. Hence, it is urgent to further understand the principles and potential mechanisms of hepatic effects on NiNPs administration. In this study, we explored the liver impacts in male C57/BL6 mice through intraperitoneal injection with NiNPs at doses of 10, 20 and 40 mg/kg/day for 7 and 28 days. The results showed that NiNPs treatment increased serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and induced pathological changes in liver tissues. Moreover, hepatic triglyceride (TG) content and lipid droplet deposition identified via de novo lipogenesis (DNL) progression were enhanced after NiNPs injection. Additionally, sustained NiNPs exposure induced a remarkable hepatic inflammatory response, significantly promoted endoplasmic reticulum stress (ER stress) sensors Ire1α, Perk and Atf6, and activated the occurrence of liver cell apoptosis. Overall, the research indicated that NiNPs exposure induced liver injury and disturbance of lipid metabolism. These findings revealed the public hazard from extreme exposure to NiNPs and provided new information on biological toxicity and biosafety evaluation.

Assessment of essential and toxic elemental concentrations in tumor and non-tumor tissues with risk of colorectal carcinoma in Pakistan

BACKGROUND

Colorectal tumor is a major cause of cancer morbidity and mortality both in USA and around the globe. Exposure to environmental toxicants such as toxic trace elements has been implicated in colorectal malignancy. However, data linking them to this cancer are generally lacking.

METHODS

Accordingly, the current study was to investigate the distribution, correlation and chemometric evaluation of 20 elements (Ca, Na, Mg, K, Zn, Fe, Ag, Co, Pb, Sn, Ni, Cr, Sr, Mn, Li, Se, Cd, Cu, Hg and As) in the tumor tissues (n = 147) and adjacent non tumor tissues (n = 147) of same colorectal patients which were analyzed by flame atomic absorption spectrophometry employing nitric acid-perchloric acid based wet digestion method.

RESULTS

On the average, Zn (p < 0.05), Ag (p < 0.001), Pb (p < 0.001), Ni (p < 0.01), Cr (p < 0.005) and Cd (p < 0.001) showed significantly higher levels in the tumor tissues compared with the non tumor tissues of patients, whereas mean levels of Ca (p < 0.01), Na (p < 0.05), Mg (p < 0.001), Fe (p < 0.001), Sn (p < 0.05) and Se (p < 0.01), were significantly elevated in the non tumor tissues than the tissues of tumor patients. Most of the elements revealed markedly disparities in their elemental levels based on food (vegetarian/nonvegetarian) habits and smoking (smoker/nonsmoker) habits of donor groups. The correlation study and multivariate statistical analyses demonstrated some significantly divergent associations and apportionment of the elements in the tumor tissues and non tumor tissues of donors. Noticeably, variations in the elemental levels were also noted for colorectal tumor types (lymphoma, carcinoids tumor and adenocarcinoma) and stages (I, II, III, & IV) in patients.

CONCLUSION

Overall, the study revealed that disproportions in essential and toxic elemental concentrations in the tissues are involved in pathogenesis of the malignancy. These findings provide the data base that helps to oncologist for diagnosis and prognosis of colorectal malignant patients.

Association between metal(loid)s in serum and leukemia: a systematic review and meta-analysis

Purpose

Heavy metals and metalloids are recognized as environmental threats, which are considered highly toxic and carcinogenic. Epidemiologically, their association with leukemia is under debate. We aim to clarify the association between the heavy metal(loid)s in serum and leukemia via a systematic review and meta-analysis.

Methods

We searched PubMed, Embase, Google Scholar, and CNKI (China National Knowledge Infrastructure) databases for all related articles. The standardized mean difference and its 95% confidence interval was used to evaluate the association of leukemia with heavy metal(loid)s in serum. The statistical heterogeneity among studies was assessed with the Q-test and I 2 statistics.

Results

Among 4,119 articles related to metal(loid)s and leukemia, 21 studies met our inclusion criteria, which are all cross-sectional studies. These 21 studies involved 1,316 cases and 1,310 controls, based on which we evaluate the association of heavy metals/metalloids in serum with leukemia. Our results indicated positive differences for serum chromium, nickel, and mercury in leukemia patients, while a negative difference for serum manganese in acute lymphocytic leukemia (ALL).

Conclusion

Our results suggested an elevated trend of serum chromium, nickel, and mercury concentrations in leukemia patients while descending trend of serum manganese concentration in ALL patients. The result of sensitivity analysis between lead, cadmium, and leukemia and publication bias of association between chromium and leukemia also needed attention. Future research work may focus on the dose-response relationship between any of these elements and the leukemia risks, and further elucidation of how these elements are related to leukemia may shed light on the prevention and treatment of leukemia.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-023-00853-2.

Nickel induces hepatotoxicity by mitochondrial biogenesis, mitochondrial dynamics, and mitophagy dysfunction

Nickel (Ni) is an important and widely hazardous chemical industrial waste. Excessive Ni exposure could cause multi-organs toxicity in human and animals. Liver is the major target organ of Ni accumulation and toxicity, however, the precise mechanism is still unclear. In this study, nickel chloride (NiCl₂ )-treatment induced hepatic histopathological changes in the mice, and, transmission electron microscopy results showed mitochondrial swollen and deformed of hepatocyte. Next, the mitochondrial damages including mitochondrial biogenesis, mitochondrial dynamics, and mitophagy were measured after NiCl₂ administration. The results showed that NiCl₂ suppressed mitochondrial biogenesis by decreasing PGC-1α, TFAM, and NRF1 protein and mRNA expression levels. Meanwhile, the proteins involved in mitochondrial fusion were reduced by NiCl₂ , such as Mfn1 and Mfn2, however, mitochondrial fission proteins Drip1 and Fis1 were significantly increased. The up-regulation of mitochondrial p62 and LC3II expression indicated that NiCl₂ increased mitophagy in the liver. Moreover, the receptor-mediated mitophagy and ubiquitin (Ub)-dependent mitophagy were detected. NiCl₂ promoted PINK1 accumulation and Parkin recruitment on mitochondria. And, the receptor proteins of mitophagy Bnip3 and FUNDC1 were increased in the NiCl₂ -treated mice liver. Overall, these results show that NiCl₂ could induce mitochondria damage in the liver of mice, and, dysfunction of mitochondrial biogenesis, mitochondrial dynamics and mitophagy involved in the molecular mechanism of NiCl₂ -induced hepatotoxicity.

Recent Overview of Potent Antioxidant Activity of Coordination Compounds

During recent decades, the complexation of organic ligands toward several metal ions of s-p and d-block has been applied as a plan to enhance its antioxidant performance. Due to their wide range of beneficial impacts, coordination compounds are widely used in industries, specifically in the medicinal and pharmaceutical fields. The activity is generally improved by chelation consequently knowing that the characteristics of both ligands and metals can lead to the development of greatly active compounds. Chelation compounds are a substitute for using the traditional synthetic antioxidants, because metal chelates present benefits, including a variety in geometry, oxidation states, and coordination number, that assist and favor the redox methods associated with antioxidant action. As well as understanding the best studied anti-oxidative assets of these compounds, coordination compounds are involved in the free radical scavenging process and protecting human organisms from the opposing effects of these radicals. The antioxidant ability can be assessed by various interrelated systems. The methodological modification offers the most knowledge on the antioxidant property of metal chelates. Colorimetric techniques are the most used, though electron paramagnetic resonance (EPR) is an alternative for metallic compounds, since color does not affect the results. Information about systems, with their benefits, and restrictions, permits a dependable valuation of the antioxidant performance of coordination compounds, as well as assisting application in various states wherever antioxidant drugs are required, such as in food protection, appropriate good-packaged foods, dietary supplements, and others. Because of the new exhaustive analysis of organic ligands, it has become a separate field of research in chemistry. The present investigation will be respected for providing a foundation for the antioxidant properties of organic ligands, future tests on organic ligands, and building high-quality antioxidative compounds.

"Assessing exposure of printing factory workers in thailand to selected heavy metals using urine and hair as non-invasive matrices"

BACKGROUND

There are few thorough studies on the extent and inter-element relationships of heavy metal contamination in printing factory workers, especially in developing countries. The objective of this study was to determine the levels of eight heavy metals, including arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), cobalt (Co), lead (Pb), mercury (Hg), and manganese (Mn), in urine and scalp hair of printing industry workers, and assess inter-element correlations.

METHODS

We examined a total of 85 urine samples and 85 scalp hair samples (3 cm hair segments taken from near the scalp) in 85 printing workers from a printing house in Bangkok, Thailand. We used an interviewer-administered questionnaire about participants' printing techniques, work characteristics, and work environment. Urine and scalp hair samples were analyzed for levels of each element using the inductively coupled plasma optical emission spectrometry (ICP-OES) technique.

RESULTS

As, Cd, Cr, Ni, Pb were detected in urine with the geometric mean concentration range of 0.0028-0.0209 mg/L, and Hg, Pb, Ni, Cd, Co, Mn, Cr were detected in hair samples (0.4453-7.165 mg/kg dry weight) of printing workers. The geometric mean Ni level was significantly higher in the urine of production line workers than back-office personnel (0.0218 mg/L vs. 0.0132 mg/L; p = 0.0124). The other elements did not differ significantly between production line and back-office workers in either urine or hair. There was also a strong, statistically significant positive correlation between Ni and Co levels in hair samples of workers (r = 0.944, p < 0.0001).

CONCLUSIONS

Average concentrations of most of the metals in urine and hair of printing workers were found to be above the upper reference values. The significantly higher concentrations of Ni in production line workers might be due to more exposure to printed materials. A strong inter-element correlation between Ni and Co in hair samples can increase stronger health effects and should be further investigated. This study reveals possible dependencies and impact interactions of heavy metal exposure in printing factory workers.

Nickel nanoparticles exert cytotoxic effects on trophoblast HTR-8/SVneo cells possibly via Nrf2/MAPK/caspase 3 pathway

Nickel nanoparticles are widely used in the industry and may affect the reproductive system. The potential molecular mechanism of exposing the first-trimester trophoblast cell line (HTR-8/SVneo) to nickel nanoparticles remains unclear. Hence, the aim of this study was to investigate the in vitro cytotoxicity of Ni NPs on HTR-8/SVneo cells. HTR-8/SVneo cells were subjected to various concentrations (0, 2.5, 5, 7.5, 10, and 12.5 μg/cm²) of Ni NPs. The toxicity of the Ni NPs was evaluated in HTR-8/SVneo cells by measuring cell viability. The underlying mechanism of nickel nanoparticles toxicity to HTR-8/SVneo cells was determined by measuring the content of intracellular reactive oxygen species, mitochondrial membrane potential, and the rate of cell apoptosis and cell cycle, by measuring adenosine triphosphate levels, intracellular lipid peroxidation malondialdehyde, total superoxide dismutase, and CuZn/Mn-SOD activities, and by determining proteins related to Nrf2, MAPK, and Cytochrome c. Our results showed that the nickel nanoparticles treatment reduced the viability of HTR-8/SVneo cells, while it increased their oxidative stress and lowered their mitochondrial respiratory capacity. Additionally, the nickel nanoparticles treatment induced cell S-phase arrest and apoptosis. These molecular events may be linked to the oxidative stress-Nrf2 pathway/MAPK/Caspase 3 cascade. Thus, nickel nanoparticles exert cytotoxic effects on HTR-8/SVneo cells, which could affect the function of the placenta in human.

HMG20A was identified as a key enhancer driver associated with DNA damage repair in oral squamous cell carcinomas

Background

Oral squamous cell carcinoma (OSCC) is the main type of oral cancer. Disturbing DNA repair is an invaluable way to improve the effectiveness of tumor treatment. Here, we aimed to explore the key enhancer drivers associated with DNA damage repair in OSCC cells.

Methods

Gene Set Enrichment Analysis (GSEA), Gene Set Variation Analysis (GSVA) and Kaplan-Meier analysis were applied to explore the relationship among DNA repair-related genes expression and clinical phenotypes based on The Cancer Genome Atlas (TCGA) database. HOMER software and Integrative Genomics Viewer were applied to identify and visualize enhancers using GSE120634. Toolkit for Cistrome Data Browser was applied to predict transcription factors. Human Protein Atlas Database was used to analyze the protein levels of transcription factors in OSCC and control tissues. Seventy-two OSCC patients were included in this study. qRT-PCR was used to detect transcription factor expression in OSCC and adjacent control tissues collected in this study. qRT-PCR and ChIP-qPCR were used to verify the binding of transcription factors to enhancers, and regulation of target genes transcription. Transcription factor knockdown and control cells were treated with cisplatin. CCK8 was used to detect cell viability and proliferation. Western blotting was implemented to detect the levels of DNA repair-related proteins. Transwell assay was used to detect cell invasion.

Results

DNA repair was positively associated with the OSCC metastatic phenotype. Patients in the cluster with high expression of DNA repair-related genes had a worse prognosis and a higher proportion of advanced stage, low-differentiation, alcohol consumption and smoking compared to the cluster with low DNA repair-related gene expression. Seventeen metastasis-specific enhancer-controlled upregulated DNA repair-related genes, with the top two upregulated genes being ADRM1 26 S proteasome ubiquitin receptor (ADRM1) and solute carrier family 12 member 7 (SLC12A7) were screened. High mobility group 20 A (HMG20A) was the key prognostic enhancer driver regulating metastasis-specific DNA repair-related genes, with higher expression in OSCC tissues than normal control tissues, and higher expression in metastatic OSCC tissues than non-metastatic OSCC tissues. HMG20A bound to the metastasis-specific enhancers of ADRM1 and SLC12A7, thereby promoting ADRM1 and SLC12A7 expression. Knockdown of HMG20A enhanced cisplatin sensitivity of cells, and inhibited OSCC cells from repairing DNA damage caused by cisplatin, as well as proliferation and invasion of OSCC cells.

Conclusion

HMG20A was identified as the key prognostic enhancer driver regulating DNA repair in OSCC cells, providing a new therapeutic target for OSCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02500-y.

Circulating metals, leukocyte microRNAs and microRNA networks: A profiling and functional analysis in Chinese adults

BACKGROUND

Metals in the human body represent both environmental exposure and nutritional status. Little is known about the miRNA signature in relation to circulating metals in humans.

OBJECTIVES

To characterize metal-associated miRNAs in leukocytes, individually and collectively as networks.

METHODS

In a panel of 160 Chinese adults, we measured 23 metals/metalloids in plasma, and sequenced miRNAs and mRNAs in leukocytes. We used linear regression to model the associations between ln-transformed metal concentrations and normalized miRNA levels adjusting for potential confounders. We inferred the enriched leukocyte subtypes for the identified miRNAs using an association approach. We utilized mRNA sequencing data to explore miRNA functions. We also constructed modules to identify metal-associated miRNA networks.

RESULTS

We identified 55 metal-associated miRNAs at false discovery rate-adjusted P < 0.05. In particular, we found that lead, nickel, and vanadium were positively associated with potentially lymphocyte-enriched miR-142-3p, miR-150-3p, miR-28-5p, miR-361-3p, and miR-769-5p, and were inversely associated with potentially granulocyte-enriched let-7a/c/d-5p and miR-1294. Interestingly, the five lymphocyte-enriched miRNAs inhibited, whereas miR-1294 activated, ROS and DNA repair pathways. We further confirmed the findings using oxidative damage biomarkers. Next, we clustered co-expressed miRNAs into modules, and identified four miRNA modules that were associated with different metals. The identified modules represented miRNAs enriched in different leukocyte subtypes, and were involved in biological processes including hematopoiesis and immune response, mitochondrial functions, and response to the stimulus.

CONCLUSIONS

At commonly exposed low levels, circulating metals were associated with distinct miRNA signatures in leukocytes. The identified miRNAs, individually or as regulatory networks, may provide a mechanistic link between metal exposure and pathophysiological changes in the immune system.

Mechanism of effects of nickel or nickel compounds on intestinal mucosal barrier

As an important metal in industry, national defense, and production, nickel widely exists in nature and is also a necessary trace element for human beings and animals. Nickel deficiency will affect the growth and development of animals, the contents of related active substances, enzymes and other essential elements in vivo. However, excessive nickel or longer nickel exposure can induce excessive free radicals (reactive oxygen species and reactive nitrogen) in the body, which can lead to a variety of cell damage, apoptosis and canceration, and ultimately pose negative effects on the health of the body. Among them, the intestinal tract, as the largest interface between the body and the external environment, greatly increases the contact probability between nickel or nickel compounds and the intestinal mucosal barrier, thus, the intestinal structure and function are also more vulnerable to nickel damage, leading to a series of related diseases such as enteritis. Therefore, this paper briefly analyzed the damage mechanism of nickel or its compounds to the intestinal tract from the perspective of four intestinal mucosal barriers: mechanical barrier, immune barrier, microbial barrier and chemical barrier, we hope to make a certain theoretical contribution to the further research and the prevention and treatment of nickel related diseases.

The Ni(II)-Binding Activity of the Intrinsically Disordered Region of Human NDRG1, a Protein Involved in Cancer Development

Nickel exposure is associated with tumors of the respiratory tract such as lung and nasal cancers, acting through still-uncharacterized mechanisms. Understanding the molecular basis of nickel-induced carcinogenesis requires unraveling the mode and the effects of Ni(II) binding to its intracellular targets. A possible Ni(II)-binding protein and a potential focus for cancer treatment is hNDRG1, a protein induced by Ni(II) through the hypoxia response pathway, whose expression correlates with higher cancer aggressiveness and resistance to chemotherapy in lung tissue. The protein sequence contains a unique C-terminal sequence of 83 residues (hNDRG1*C), featuring a three-times-repeated decapeptide, involved in metal binding, lipid interaction and post-translational phosphorylation. In the present work, the biochemical and biophysical characterization of unmodified hNDRG1*C was performed. Bioinformatic analysis assigned it to the family of the intrinsically disordered regions and the absence of secondary and tertiary structure was experimentally proven by circular dichroism and NMR. Isothermal titration calorimetry revealed the occurrence of a Ni(II)-binding event with micromolar affinity. Detailed information on the Ni(II)-binding site and on the residues involved was obtained in an extensive NMR study, revealing an octahedral paramagnetic metal coordination that does not cause any major change of the protein backbone, which is coherent with CD analysis. hNDRG1*C was found in a monomeric form by light-scattering experiments, while the full-length hNDRG1 monomer was found in equilibrium between the dimer and tetramer, both in solution and in human cell lines. The results are the first essential step for understanding the cellular function of hNDRG1*C at the molecular level, with potential future applications to clarify its role and the role of Ni(II) in cancer development.

Unboxing the molecular modalities of mutagens in cancer

The etiology of the majority of human cancers is associated with a myriad of environmental causes, including physical, chemical, and biological factors. DNA damage induced by such mutagens is the initial step in the process of carcinogenesis resulting in the accumulation of mutations. Mutational events are considered the major triggers for introducing genetic and epigenetic insults such as DNA crosslinks, single- and double-strand DNA breaks, formation of DNA adducts, mismatched bases, modification in histones, DNA methylation, and microRNA alterations. However, DNA repair mechanisms are devoted to protect the DNA to ensure genetic stability, any aberrations in these calibrated mechanisms provoke cancer occurrence. Comprehensive knowledge of the type of mutagens and carcinogens and the influence of these agents in DNA damage and cancer induction is crucial to develop rational anticancer strategies. This review delineated the molecular mechanism of DNA damage and the repair pathways to provide a deep understanding of the molecular basis of mutagenicity and carcinogenicity. A relationship between DNA adduct formation and cancer incidence has also been summarized. The mechanistic basis of inflammatory response and oxidative damage triggered by mutagens in tumorigenesis has also been highlighted. We elucidated the interesting interplay between DNA damage response and immune system mechanisms. We addressed the current understanding of DNA repair targeted therapies and DNA damaging chemotherapeutic agents for cancer treatment and discussed how antiviral agents, anti-inflammatory drugs, and immunotherapeutic agents combined with traditional approaches lay the foundations for future cancer therapies.

Effect of nickel (II) on the performance of anodic electroactive biofilms in bioelectrochemical systems

The impact of nickel (Ni²⁺) on the performance of anodic electroactive biofilms (EABs) in the bioelectrochemical system (BES) was investigated in this study. Although it has been reported that Ni²⁺ influences microorganisms in a number of ways, it is unknown how its presence in the anode of a BES affects extracellular electron transfer (EET) of EABs, microbial viability, and the bacterial community. Results revealed that the addition of Ni²⁺ decreased power output from 673.24 ± 12.40 mW/m² at 0 mg/L to 179.26 ± 9.05 mW/m² at 80 mg/L. The metal and chemical oxygen demand removal efficiencies of the microbial fuel cells (MFCs) declined as Ni²⁺ concentration increased, which could be attributed to decreased microbial viability as revealed by SEM and CLSM. FTIR analysis revealed the involvement of various microbial biofilm functional groups, including hydroxyl, amides, methyl, amine, and carboxyl, in the uptake of Ni²⁺. The presence of Ni²⁺ on the anodic biofilms was confirmed by SEM-EDS and XPS analyses. CV demonstrated that the electron transfer performance of the anodic biofilms was negatively correlated with the various Ni²⁺ concentrations. EIS showed that the internal resistance of the MFCs increased with increasing Ni²⁺ concentration, resulting in a decrease in power output. High-throughput sequencing results revealed a decrease in Geobacter and an increase in Desulfovibrio in response to Ni²⁺ concentrations of 10, 20, 40, and 80 mg/L. Furthermore, the various Ni²⁺ concentrations decreased the expression of EET-related genes. The Ni²⁺-fed MFCs had a higher abundance of the nikR gene than the control group, which was important for Ni²⁺ resistance. This work advances our understanding of Ni²⁺ inhibition on EABs, as well as the concurrent removal of organic matter and Ni²⁺ from wastewater.

Exposure to metal mixtures and hypertensive disorders of pregnancy: A nested case-control study in China

Exposure to metals has been linked with the risk of hypertensive disorders of pregnancy (HDP), but little is known about the potential effects of exposure to metal mixtures. Thus, our study aimed to investigated the impact of a complex mixture of metals on HDP, especially the interactions among metal mixtures. We did a population-based nested case-control study from October 2013 to October 2016 in Wuhan, China, including 146 HDP cases and 292 controls. Plasma concentrations of Aluminum (Al), Barium (Ba), Cobalt (Co), Copper (Cu), Lead (Pb), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Selenium (Se), Strontium (Sr), Thallium (Tl), and Vanadium (V) were measured and collected between 10 and 16 gestational weeks. We employed quantile g-computation, conditional logistic regression models, and Bayesian Kernel Machine Regression (BKMR) to assess the association of individual metals and metal mixtures with HDP risk. In the quantile g-computation, the OR for a joint tertile increase in plasma concentrations was 3.67 (95% CI: 1.70, 7.91). Hg contributed the largest positive weights and followed by Al, Ni, and V. In conditional logistic regression models, concentrations of Hg, Al, Ni, and V were significantly associated with the risk of HDP (p-FDR < 0.05). Compared to the lowest tertiles, the ORs (95% CI) for the highest tertiles of these four metals were 2.67 (1.44, 4.95), 3.09 (1.70, 5.64), 5.31 (2.68, 10.53), and 4.52 (2.26, 9.01), respectively. In the BKMR analysis, we observed a linear positive association between Hg, Al, V, and HDP, and a nonlinear relationship between Ni and HDP. A potential interaction between Al and V was also identified. We found that exposure to metal mixtures in early pregnancy, both individually and as a mixture, was associated with the risk of HDP. Potential interaction effects of Al and V on the risk of HDP may exist.

Developing Benign Ni/g-C3N4 Catalysts for CO2 Hydrogenation: Activity and Toxicity Study

This research discusses the CO₂ valorization via hydrogenation over the non-noble metal clusters of Ni and Cu supported on graphitic carbon nitride (g-C₃N₄). The Ni and Cu catalysts were characterized by conventional techniques including XRD, AFM, ATR, Raman imaging, and TPR and were tested via the hydrogenation of CO₂ at 1 bar. The transition-metal-based catalyst designed with atom-economy principles presents stable activity and good conversions for the studied processes. At 1 bar, the rise in operating temperature during CO₂ hydrogenation increases the CO₂ conversion and the selectivity for CO and decreases the selectivity for methanol on Cu/CN catalysts. For the Ni/CN catalyst, the selectivity to light hydrocarbons, such as CH₄, also increased with rising temperature. At 623 K, the conversion attained ca. 20%, with CH₄ being the primary product of the reaction (CH₄ yield >80%). Above 700 K, the Ni/CN activity increases, reaching almost equilibrium values, although the Ni loading in Ni/CN is lower by more than 90% compared to the reference NiREF catalyst. The presented data offer a better understanding of the effect of the transition metals’ small metal cluster and their coordination and stabilization within g-C₃N₄, contributing to the rational hybrid catalyst design with a less-toxic impact on the environment and health. Bare g-C₃N₄ is shown as a good support candidate for atom-economy-designed catalysts for hydrogenation application. In addition, cytotoxicity to the keratinocyte human HaCaT cell line revealed that low concentrations of catalysts particles (to 6.25 μg mL^–1) did not cause degenerative changes.

Toxic effect of nickel on microalgae Phaeodactylum tricornutum (Bacillariophyceae)

Nickel acts as an essential trace nutrient or toxicant for organisms, depending on its concentration. The increased concentrations of nickel, due to anthropogenic activity, in the aquatic environment are potential threats to aquatic organisms. However, the knowledge on toxic mechanisms of nickel to microalgae remains incompletely understood. In the present study, we investigated the toxic effects of nickel in the cosmopolitan diatom Phaeodactylum tricornutum via evaluation of physiological and transcriptome responses. The results showed that the median effective concentration-72 h (EC₅₀-72 h) and EC₅₀-96 h of nickel was 2.48 ± 0.33 and 1.85 ± 0.17 mg/L, respectively. The P. tricornutum cell abundance and photosynthesis significantly decreased by 1 mg/L of nickel. Results from photosynthetic parameters including efficiency of the oxygen evolving complex (OEC) of photosystem II (PSII) (Fv/F₀), maximum photosynthetic efficiency of PS II (Fv/Fm), electron transport rate (ETR), actual photosynthetic efficiency of PS II (Y(II)), non-photochemical quenching (NPQ), and photochemical quenching (qP) indicated that OEC of PS II might be impaired by nickel. The transcriptome data also reveal that OEC apparatus coding gene PS II oxygen-evolving enhancer protein 2 (PsbP) was regulated by nickel. Moreover, induced reactive oxygen species (ROS) production and chlorophyll a content were also detected under nickel stress. Transcriptome analysis revealed that nickel affected a variety of differentially expressed genes (DEGs) that involved in redox homeostasis, nitrogen metabolisms, fatty acids, and DNA metabolism. However, thiol-disulfide redox system might play important roles in nickel-induced oxidative stress resistance. This study improved the understanding of the toxic effect of nickel on the diatom P. tricornutum.

Recent advances in the application of metallomics in diagnosis and prognosis of human cancer

Metals play a critical role in human health and diseases. In recent years, metallomics has been introduced and extensively applied to investigate the distribution, regulation, function, and crosstalk of metal(loid) ions in various physiological and pathological processes. Based on high-throughput multielemental analytical techniques and bioinformatics methods, it is possible to elucidate the correlation between the metabolism and homeostasis of diverse metals and complex diseases, in particular for cancer. This review aims to provide an overview of recent progress made in the application of metallomics in cancer research. We mainly focuses on the studies about metallomic profiling of different human biological samples for several major types of cancer, which reveal distinct and dynamic patterns of metal ion contents and the potential benefits of using such information in the detection and prognosis of these malignancies. Elevated levels of copper appear to be a significant risk factor for various cancers, and each type of cancer has a unique distribution of metals in biofluids, hair/nails, and tumor-affected tissues. Furthermore, associations between genetic variations in representative metalloprotein genes and cancer susceptibility have also been demonstrated. Overall, metallomics not only offers a better understanding of the relationship between metal dyshomeostasis and the development of cancer but also facilitates the discovery of new diagnostic and prognostic markers for cancer translational medicine.

Metformin alleviates nickel-refining fumes-induced aerobic glycolysis via AMPK/GOLPH3 pathway in vitro and in vivo

Nickel (Ni) compounds is recognized industrial carcinogen, which could increase the risk of lung cancer in Ni refineries workers. However, the underlying carcinogenic mechanism still remains to elucidate. Metformin has shown the anticancer properties through suppressing aerobic glycolysis. In the present study, we evaluated the effect of Ni-refining fumes exposure on aerobic glycolysis and the role of AMPK/GOLPH3, as well as how metformin alleviated nickel-induced aerobic glycolysis in vitro and vivo. Firstly, Beas-2B cells were exposed to different concentrations of Ni-refining fumes and pretreated with metformin (activation of AMPK), compound C (AMPK inhibitor) in vitro. Our findings indicated that Ni fumes expose evoked aerobic glycolysis by AMPK/GOLPH3, while metformin attenuated Ni particles-promoted GOLPH3-mediated aerobic glycolysis by p-AMPK expression increase. Then Mito-TEMPT (a mitochondria-targeted antioxidant) and lipopolysaccharide (LPS, ROS activator) were pretreated to affect ROS production in Beas-2B cells. Ni-induced ROS prevented AMPK activation. Moreover, C57BL/6 mice were exposed to 2 mg/kg Ni by non-exposed endotracheal instillation and metformin (100, 200 and 300 mg/kg) via oral gavage for 4 weeks. The effects of AMPK/GOLPH3 axis on Ni-induced aerobic glycolysis were assessed. The results indicated that metformin decreased the protein levels of GOLPH3, LDHA, HK2, MCT-4 and improved p-AMPK expression. Thus, our findings demonstrated metformin antagonized Ni-refining fumes-caused aerobic glycolysis via AMPK/GOLPH3.

Circular RNA circNIPBL promotes NNK-induced DNA damage in bronchial epithelial cells via the base excision repair pathway

Environmental chemical exposure often causes DNA damage, which leads to cellular dysfunction and the development of diseases. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific carcinogen that is known to cause DNA damage, while remains unknown about the underlying mechanism. In this study, simulated doses of NNK exposure in smokers, ranging from 50 to 300 μM, were used to detect the DNA damage effects of NNK in two human bronchial epithelial cells, 16HBE and BEAS-2B. The comet assay revealed increased DNA damage in response to NNK treatment, as measured by increased Olive tail moment (OTM). NNK treatment also led to elevated foci formation and protein expression of γ-H2AX, a DNA damage sensor. Dysregulation of proliferation, cell cycle arrest and apoptosis, was also observed in NNK-treated cells. Furthermore, the most effective dose of NNK (300 μM) was used in subsequent mechanistic studies. A circular RNA circNIPBL was identified to be significantly up-regulated in NNK-treated cells, circNIPBL knockdown successfully alleviated NNK-induced DNA damage and reversed the cellular dysregulation, while circNIPBL overexpression had the opposite effect. Mechanistically, we identified an interaction between circNIPBL and PARP1, a critical enzyme of the base excision repair (BER) pathway. CircNIPBL silencing successfully alleviated the NNK-induced inhibition of BER pathway proteins, including PARP1, XRCC1, PCNA and FEN1, while overexpression of circNIPBL had the opposite effect. In summary, our study shows for the first time that circNIPBL promotes NNK-induced DNA damage and cellular dysfunction through the BER pathway. In addition, our findings reveal the crucial role of epigenetic regulation in carcinogen-induced genetic lesions and further our understanding of environmental carcinogenesis.

Biomonitoring of Urinary Nickel Successfully Protects Employees and Introduces Effective Interventions

Nickel is a heavy metal used in many industries. Nickel exposure can induce respiratory diseases and allergic reactions, and increase cancer risk. This study evaluated the introduction of a grinding and polishing system to prevent injuries from nickel toxicity in workers. We performed a controlled, interventional, before-and-after study from January 2018 to December 2019 at a faucet component industrial manufacturing site. Results from workplace environmental monitoring, questionnaire responses, and biomonitoring were collected before and after the intervention. Thirty-seven workers (100% men) aged 25.0 (interquartile range (IQR): 22.0–33.5) years were categorized into two groups, those with and without nickel exposure. In the exposed group, the median exposure time was 18.0 months (IQR 14.0–20.0 months). Urinary nickel concentration was lower in the exposed group than in the non-exposed group (13.8 (IQR 1.7–20.7); 23.1 (IQR 11.3–32.8) μg/g creatinine, respectively; p = 0.047). The median urinary nickel concentration was lower in the second year than in the first year (17.4 (IQR 2.2–27.4), 7.7 (IQR 4.3–18.5) μg/g creatinine, respectively; p = 0.022). Significant reductions in urinary nickel concentration were observed following the intervention and educational program. Thus, biomonitoring of urinary nickel concentration can successfully reflect the effectiveness of interventions and their relationship to nickel exposure.

Food safety of the green tiger shrimp Penaeus semisulcatus from the Persian Gulf

Seafood is a rich source of essential compounds for human health, but the consumption of aquatic products that are exposed to environmental pollutants, especially trace metals, comes with risk. Therefore, in this study, the levels of nickel, zinc, and lead in the muscle of shrimp Penaeus semisulcatus caught from the north of the Persian Gulf as a polluted environment were measured, and the health risks were assessed. The results showed that the level of Zn (300.88 ± 2.76 µg/g) in the muscle of shrimp was higher than Ni (6.82 ± 0.10) and Pb (1.10 ± 0.09 µg/g), and the amount of accumulation of all three metals is higher than the allowable limit proposed by the FAO/WHO. According to values of estimated daily intake (EDI) and target hazard quotient (THQ), the consumption of shrimp has no or minimal risk for health. However, the target cancer risk (TR) of Ni (adult, 0.00294; child, 0.00196) indicated that Ni accumulation is associated with carcinogenic risks. These findings may be helpful in the proper management of seafood quality and public health in the Persian Gulf.

A comprehensive review on the sources, essentiality and toxicological profile of nickel

This review contains up-to-date knowledge and recent advancements on the essentiality, sources, and toxicological profile of nickel and its different compounds. Nickel is a recognized essential element for several important biological processes like the healthy growth of plants, animals, and soil/water microbes; though an excess amount of nickel intoxicates flora and fauna. Nickel is found to affect the photosynthetic function of higher plants; it can severely degrade soil fertility and causes many chronic diseases in humans. Due to the huge growth in the nickel industry and consumption of nickel-containing products, environmental pollution has become inevitable by the element nickel and also varieties of its by-products through all the phases of making, utilization and dumping. We have focused on the importance of agenda 2030 (UN 17 SDGs) during the preparation of the write-up and have highlighted goals 3, 6, 8, 9, 11, 12, 13, 14, and 15 by elaborately discussing associated points. The plausible molecular mechanism of nickel toxicity is presented in simple diagrams. The article elaborates on possible methods for remediation of nickel toxicity and the treatment of nickel dermatitis and nickel cancer. Recent advancements in the understanding of the dual aspects of nickel as beneficial and a carcinogen are the key subject of this article.

This review contains up-to-date knowledge and recent advancements on the essentiality, sources, and toxicological profile of nickel and its different compounds.

Immunomodulatory effects of curcumin in systemic autoimmune diseases

Systemic autoimmune diseases like rheumatoid arthritis, multiple sclerosis, and systemic lupus erythematosus represent various autoimmune conditions identified by immune system dysregulation. The activation of immune cells, auto-antigen outbreak, inflammation, and multi-organ impairment is observed in these disorders. The immune system is an essential complex network of cells and chemical mediators which defends the organism's integrity against foreign microorganisms, and its precise operation and stability are compulsory to avoid a wide range of medical complications. Curcumin is a phenolic ingredient extracted from turmeric and belongs to the Zingiberaceae, or ginger family. Curcumin has multiple functions, such as inhibiting inflammation, oxidative stress, tumor cell proliferation, cell death, and infection. Nevertheless, the immunomodulatory influence of curcumin on immunological reactions/processes remains mostly unknown. In the present narrative review, we sought to provide current information concerning the preclinical and clinical uses of curcumin in systemic autoimmune diseases.

Carcinogenic Risk of Pb, Cd, Ni, and Cr and Critical Ecological Risk of Cd and Cu in Soil and Groundwater around the Municipal Solid Waste Open Dump in Central Thailand

Several consequences of health effects from municipal solid waste caused by carcinogenic and noncarcinogenic metals have been recognized. The water quality index ( $\text{WQI}$ ) in the groundwater around this landfill is 2945.58, which is unacceptable for consumption. The contaminated groundwater mainly appears within a 1 km radius around the landfill. The metal pollution levels in the soil in descending order were Cu > Cd > Zn=Cr > Pb > Ni. The pollution degree (ER) of Cd was 2898.88, and the potential ecological risk index (RI) was 2945.58, indicating that the risk level was very high. Surprisingly, the hazard index (HI) of Pb (2.05) and Fe (1.59) in children was higher than 1. This indicated that the chronic risk and cancer risk caused by Pb and Fe for children were at a medium level. Carcinogenic risk by oral (CR oral) consumption of Ni, Cd, and Cr in children was 1.4E − 04, 2.5E − 04, and 1.8E − 04, respectively, while the lifetime carcinogenic risk (LCR) of Ni, Cd, and Cr in children was 1.5E − 04, 2.8E − 04, and 2.0E − 04, respectively. In adults, CR oral of Ni and Cr were 1.6E − 03 and 3.0E − 04, respectively, while LCR of Ni and Cr were 1.6E − 03 and 3.4E − 04, respectively, which exceeded the carcinogenic risks limits. Our study indicated a lifetime carcinogenic risk to humans. Environmental surveillance should focus on reducing health risks such as continuous monitoring of the groundwater, soil, and leachate treatment process.

Mechanism of DNA methylation-mediated downregulation of O6-Methylguanine-DNA methyltransferase in cartilage injury of Kashin-Beck Disease

OBJECTIVE

Kashin-Beck Disease (KBD) is an endemic osteoarthropathy, in which excessive apoptosis of chondrocytes occurs. O6-methylguanine-DNA methyltransferase (MGMT), a DNA damage repair gene, plays an important role in apoptosis but the mechanism is unclear in KBD cartilage injury. This study was to investigate the expression and promoter methylation of MGMT in KBD patients and its role in DNA damage and apoptosis of chondrocytes.

METHODS

MGMT mRNA and protein level were detected by quantitative real-time PCR and immunohistochemistry. Demethylation of MGMT was carried out using 5-Aza-2'-deoxycytidine, and the methylation level of MGMT promoter was measured by quantitative methylation specific PCR. Next, shRNA was used to knockdown the expression of MGMT. Cell viability, apoptosis and DNA damage were determined by MTT assay, flow cytometry, Hoechst 33342 staining and alkaline comet assay following T-2 toxin and selenium treatment.

RESULTS

MGMT protein expression and mRNA levels were decreased (p = 0.02, p = 0.007) and promoter methylation was increased (p = 0.008) in KBD patients. Meanwhile, MGMT level was upregulated by 5-Aza-2'-deoxycytidine in chondrocytes (p = 0.0002). DNA damage and apoptosis rates were increased in MGMT-silenced chondrocytes (all p < 0.0001). Furthermore, DNA damage and apoptosis were increseaed in chondrocytes treated with T-2 toxin (all p < 0.0001), but were decreased after selenium treatment (p < 0.0001, p = 0.01). Decreased mRNA level and increased methylation of MGMT were found in T-2 toxin group (p = 0.005, p = 0.002), while selenium reversed it (p = 0.02, p = 0.004).

CONCLUSIONS

MGMT might play a crucial part in the pathogenesis of KBD cartilage injury, which providing a therapeutic target for KBD.