The mechanism of liver injury in mice caused by lanthanoids

Exploring the role of ATP-sensitive potassium channel, eNOS, and P-glycoprotein in mediating the hepatoprotective activity of nicorandil in methotrexate-induced liver injury in rats

BACKGROUND

Methotrexate (MTX) is a commonly used chemotherapeutic agent; however, its clinical use is challenged by various types of injuries, including hepatotoxic side effects. Therefore, finding new protective drugs against MTX-induced toxicities is a critical need. Moreover, the different mechanisms mediating such effects are still not clear. The current study aimed to evaluate the possible ameliorative action of nicorandil (NIC) in MTX-induced hepatotoxicity and examine the roles of the ATP-sensitive potassium channel (KATP), endothelial nitric oxide synthase (eNOS), and P-glycoprotein (P-gp).

MATERIALS AND METHODS

Thirty-six male Wistar albino rats were used. NIC (3 mg/kg/day) was given orally for 2 weeks, and hepatotoxicity was induced by a single intraperitoneal injection of MTX (20 mg/kg) on the 11th day of the experiment. We confirmed the role of KATP by co-administering glimepiride (GP) (10 mg/kg/day) 30 min before NIC. The measured serum biomarkers were [alanine transaminase (ALT) and aspartate transaminase (AST)], total antioxidant capacity (TAC), malondialdehyde (MDA), nitric oxide (NOx), tumor necrosis factor-alpha (TNFα), superoxide dismutase (SOD), and P-gp. Histopathology, eNOS, and caspase-3 immunoexpression were evaluated.

RESULTS

The MTX group displayed hepatotoxicity in the form of elevations of ALT, AST, MDA, NOx, and caspase-3 immunoexpression. Furthermore, the histopathological examination showed marked liver injury. TAC, SOD, P-gp, and eNOS immunoexpression showed significant inhibition. In the protective group, all parameters improved (P value < 0.05).

CONCLUSION

NIC has an ameliorative action against MTX-induced hepatotoxicity, most probably via its antioxidant, anti-inflammatory, and anti-apoptotic functions together with the modulation of the KATP channel, eNOS, and P-glycoprotein.

Assessment of Threshold Dose of Thoron Inhalation and Its Biological Effects by Mimicking the Radiation Doses in Monazite Placer Deposits Corresponding to the Normal, Medium and Very High Natural Background Radiation Areas

The dose contributed from thoron (²²⁰Rn) and its progeny has been neglected in the dose assessment because of its short half-life (t_1/2 = 55.6 s) and generally low concentrations. Recently, concentrations of ²²⁰Rn gas and its progeny were found to be pronounced in the traditional residential dwellings in China, on beaches of India and in other countries. Accordingly, we investigated the biological effects of thoron (²²⁰Rn) decay products in various mouse organs, succeeding inhalation of thoron gas in BALB/c mouse. We investigated the biological effects upon thoron inhalation on mouse organs with a focus on oxidative stress. These mice were divided into (4 random groups): sham inhalation, thoron inhalation for 1, 4 and 10 days. Various tissues (lung, liver and kidney) were then collected after the time points and subjected to various biochemical analyses. Immediately after inhalation, mouse tissues were excised for gamma spectrometry and 72 h post inhalation for biochemical assays. The gamma spectrometry counts and its subsequent calculation of the equivalent dose showed varied distribution in the lung, liver and kidney. Our results suggest that acute thoron inhalation showed a differential effect on the antioxidant function and exerted pathophysiological alterations via oxidative stress in organs at a higher dose. These findings suggested that thoron inhalation could alter the redox state in organs; however, its characteristics were dependent on the total redox system of the organs as well as the thoron concentration and inhalation time.

Association between rare earth element exposure during pregnancy and newborn telomere length

Telomere length (TL) is considered a marker of biological aging and lifetime health, and some epidemiological studies report that the environmental exposures may influence TL at birth. We aimed to investigate the associations between prenatal rare earth elements (REE) exposure and newborn TL. A total of 587 mother-newborn pairs were recruited during 2013 to 2015 in Wuhan, China. Maternal urinary concentrations of REE collected during three trimesters were measured by inductively coupled plasma mass spectrometry. Quantitative real-time polymerase chain reaction was used to measure relative cord blood TL. The trimester-specific associations between prenatal REE exposure and cord blood TL were evaluated using multiple informant models. Weighted quantile sum regression was used to estimate the mixture effect of urinary REE on cord blood TL. After adjustment for potential confounders, per doubling of urinary REE (Dy, Yb, Pr, Nd, and Tm) concentrations (μg/g creatinine) during the second trimester was respectively associated with 1.94% (95% CI 0.19%, 3.72%), 2.10% (95% CI 0.31%, 3.92%), 2.11% (95% CI 0.35%, 3.89%), 2.08% (95% CI 0.01%, 4.20%), and 1.38% (95% CI 0.09%, 2.70%) increase in cord blood TL. Furthermore, exposure to the mixture of REE during the second trimester was also significantly associated with increased cord blood TL (percent change 1.20%, 95% CI 0.30%, 2.11%). However, these associations were not statistically significant in the first and third trimesters. This study provides new evidence on the potential effect of prenatal REE exposure on the initial (newborn) setting of offspring's telomere biology. Further epidemiological studies are warranted to confirm our findings.

Future food contaminants: An assessment of the plant uptake of Technology-critical elements versus traditional metal contaminants

Technology-critical elements (TCEs) include most rare earth elements (REEs), the platinum group elements (PGEs), and Ga, Ge, In, Nb, Ta, Te, and Tl. Despite increasing recognition of their prolific release into the environment, their soil to plant transfer remains largely unknown. This paper provides an approximation of the potential for plant uptake by calculating bioconcentration factors (BCFs), defined as the concentration in edible vegetable tissues relative to that in cultivation soil. Here data were obtained from an indoor cultivation experiment growing lettuce, chard, and carrot on 22 different European urban soils. Values of BCFs were determined from concentrations of TCEs in vegetable samples after digestion with concentrated HNO3, and from concentrations in soil determined after 1) Aqua Regia digestion and, 2) diluted (0.1 M) HNO3 leaching. For comparison, BCFs were also determined for 5 traditional metal contaminants (TMCs; As, Cd, Cu, Pb, and Zn). The main conclusions of the study were that: 1)BCF values for the REEs were consistently low in the studied vegetables;2)the BCFs for Ga and Nb were low as well;3) the BCFs for Tl were high relative to the other measured TCEs and the traditional metal contaminants; and 4) mean BCF values for the investigated TCEs were generally highest in chard and lowest in carrot. These findings provide initial evidence that there are likely to be real and present soil-plant transfer of TCEs, especially in the case of Tl. Improvements in analytical methods and detection limits will allow this to be further investigated in a wider variety of edible plants so that a risk profile may be developed.

Review of Potentially Toxic Rare Earth Elements, Thallium and Tellurium in Plant-based Foods

In the last decades, there is an increasing inclusion of various trace metals and metalloids such as thallium, tellurium and rare earth elements (REEs; lanthanides, scandium, and yttrium) in the composition and production of alloys, in agricultural and medicinal applications, as well as in the manufacturing of hi-tech products. All these activities have led to an accumulation of the aforementioned elements both in soil and water bodies and consequently in the food chain, through discharges from mining and mineral processing, liquid industrial waste or disposal of urban and industrial products. It has been demonstrated that chronic exposure to some of these elements, even at low doses, might lead to a wide range of adverse health effects, even from the early stages of life, such as neurotoxicity, neurodevelopmental toxicity and hepatic alterations. Particularly in children, there have been studies suggesting that some of these elements might negatively affect the children's spatial learning and memory ability indirectly. Such effects are triggered by processes like the production of reactive oxygen species (ROS), lipid peroxidation and modulation of antioxidant activities. Nevertheless, the limited data from toxicological studies and their so-far naturally low occurrence levels in the environment acted as a deterrent in measuring their concentrations during routine analyses of metals in foodstuff. Thus, it is important to collect information on their occurrence data both in adults and in children's daily diet. This review sumrises the current knowledge on the concentration of these elements, in plant-based food products to identify whether a potential health risk occurs. As side projects, this Fellowship provided hands-on training on the evaluation of new biocides application and participation in the given advice to the Danish Food and Veterinary Administration, Danish Environmental Protection Agency, the Danish Medical Agency and the European Chemicals Agency.

Kidney injury and alterations of inflammatory cytokine expressions in mice following long-term exposure to cerium chloride

It has been demonstrated that the organic damages of animals can be caused by exposure to lanthanide oxides or compounds. However, the molecular mechanism of CeCl3 -induced kidney injury remains unclear. In this study, the mechanism of nephric damage in mice induced by an intragastric administration of CeCl3 was investigated. The results showed that Ce(3+) was accumulated in the kidney, which in turn led to oxidative stress, severe nephric inflammation, and dysfunction in mice. Furthermore, CeCl3 activated nucleic factor κB, which in turn increased the expression levels of tumor necrosis factor α, macrophage migration inhibitory factor, interleukin-2, interleukin-4, interleukin-6, interleukin-8, interleukin-10, interleukin-18, interleukin-1β, cross-reaction protein, transforming growth factor-β, interferon-γ, and CYP1A1, while suppressed heat shock protein 70 expression. These findings implied that Ce(3+) -induced kidney injury of mice might be associated with oxidative stress, alteration of inflammatory cytokine expression, and reduction of detoxification of CeCl3 .

Pulmonary toxicity in mice following exposure to cerium chloride

The widespread application of lanthanoids (Lns) in manufacturing industries has raised occupational and environmental health concerns about the possible increased health risks to humans exposed to Lns in their working and living environments. Numerous studies have shown that exposures to Ln cause pulmonary injury in animals, but very little is known about the molecular mechanisms of the pulmonary inflammation caused by cerium chloride (CeCl3) exposure. In this study, we evaluated the oxidative stress and molecular mechanism underlying with the pulmonary inflammation associated with chronic lung toxicity in mice treated with nasally instilled CeCl3 for 90 consecutive days. Our findings suggest that significant cerium accumulated in the lung, leading the obvious increase of the lung indices, significant increases in inflammatory cells and levels of lactate dehydrogenase, alkaline phosphate, and total protein, overproduction of reactive oxygen species and peroxidation of lipids, reduced antioxidant capacity, and pulmonary inflammation. CeCl3 exposure also activated nuclear factor κB, increased the expression of tumor necrosis factor α, cyclooxygenase-2, heme oxygenase 1, interleukin 2, interleukin 4, interleukin 6, interleukin 8, interleukin 10, interleukin 18, interleukin 1β, and CYP1A1. However, CeCl3 reduced the expression of nuclear factor κB (NF-κB)-inhibiting factor and heat shock protein 70. These findings suggest that the pulmonary inflammation caused by CeCl3 in mice is closely associated with oxidative stress and inflammatory cytokine expression.

Gene expression profile in chronic mouse liver injury caused by long-term exposure to CeCl3

Numerous studies have demonstrated lanthanide (Ln) accumulation in the liver, and the corresponding damage; however, very little work has been done to evaluate the relationship between Ln-induced liver injury and its gene expression profile in mice. In this study, liver injury and gene-expressed profiles in male mice induced by oral administration of CeCl3 (2 mg/kg) via gavage for 90 consecutive days were investigated. The results showed that cerium accumulation, liver inflammation, and hepatocyte necrosis were observed. CeCl3 exposure significantly decreased the counts of white blood cells, lymphocyte, and platelet, the reticulocyte count (Ret) and neutrophilic granulocyte percentages as well as A/G ratio, whereas markedly increased the activities of alkaline phosphatase, lactate dehydrogenase, and cholinesterase, and the concentrations of triglycerides and total cholesterol. Furthermore, microarray results of liver showed that the differential expression of 675 known function genes involved in immune/inflammation response, apoptosis, metabolic process, cell cycle, cell proliferation, cytoskeleton, oxidative stress, signal transduction, transcription, translation, and transportation in CeCl3 exposed livers, respectively. Specifically, the significant downregulation of Nt5e led to inflammation, overexpressed Cyp4a12a and great suppression of Cdkn1a resulted in hepatocyte apoptosis, marked elevation of Cel, and Cyp7b1 expression caused the metabolic disorders in mouse liver after long-term CeCl3 exposure. Therefore, these genes may be in great relation to liver damages induced by exposure to CeCl3 .

Immune dysfunction and liver damage of mice following exposure to lanthanoids

In an effort to investigate the effects of exposure to lanthanoids (Ln) on the immune response and liver function, mice were orally exposed to LaCl3 , CeCl3 , and NdCl3 at 2, 10, and 20 mg/kg doses for 30 days, respectively; lymphocyte counts, serum IgM level, hematological indices, biochemical parameters of liver functions, and histopathological changes in Ln(3+) -treated mice were assessed. Indeed, 20 mg/kg Ln(3+) significantly inhibited mice growth and reduced the counts of white blood cells, platelets, and reticulocyte in mice blood. Specifically, in these Ln(3+) -treated mice, CD3+, CD4+, CD8+, CD19+ and NK cells, and CD4+/CD8+ ratio as well as serum IgM level were decreased. Furthermore, liver function was disrupted, as evidenced by the increased alanine aminotransferase, total bilirubin, total bile acid and triglycerides, and the decreased glucose and ratio of albumin to globulin. The cytoarchitecture damage and fatty degeneration in liver caused by Ln(3+) at 20 mg/kg dose were also observed. Our findings showed that exposure to Ln affected the cell and humoral immunity and disturbed liver function in mice. In addition, Ce(3+) was found to exhibit higher toxicity than La(3+) and Nd(3+).

Oxidative stress in the kidney injury of mice following exposure to lanthanides trichloride

Environmental pollution from lanthanides (Ln) has been recognized as a major problem due to a grab exploitation of Ln mine in China. Exposure to Ln has been demonstrated to cause the nephrotoxicity, very little is known about the mechanism of oxidative damage to kidney in animals. In order to understand Ln-induced nephrotoxicity, various biochemical and chemical parameters were assayed in mouse kidney. Intragastric exposures of LaCl₃, CeCl₃, and NdCl₃ at doses of 2, 5, and 10 mg kg(-1) BW for 90 consecutive days caused nephritis or epithelial cell necrosis and oxidative stress to kidney. An increase in coefficients of the kidney, La, Ce, and Nd accumulation and histopathological changes in the kidney could be observed, followed by increased reactive oxygen species production and peroxidation levels of lipid, protein and DNA, and decreased activities of superoxide dismutase, catalase, glutathione-S-transferase and glutathione reductase as well as antioxidants such as glutathione, ascorbic acid and thiol contents. Furthermore, La, Ce, and Nd significantly suppressed expression of genes and proteins of these antioxidative enzymes in mouse kidney. In addition, kidney functions were disrupted, including an increase of the creatinine, and reductions of uric acid, urea nitrogen, calcium and phosphonium. These findings suggest that nephritis generation or epithelial cell necrosis in mice following exposure to Ln is closely associated with oxidative stress. Of these damages, the most severe was in the Ce(3+)-exposed kidneys, next in the Nd(3+)-exposed kidneys, and the least in the La(3+)-exposed kidneys, which may be attributed to the 4f electron of Ln.

Evaluation of the toxic effects of municipal wastewater effluent on mice using omic approaches

Municipal wastewater effluents (MWWE) contain a lot of trace organic pollutants, which will be a threat to environmental health. However, little information is available for the mixed toxicity of MWWE on mammals. In the present study, male mice were exposed to MWWE for 90 days, and then, histopathology and clinical biochemistry determination and transcriptomic and metabolomic profiling were conducted. The results showed that MWWE exposure resulted in injuries in liver and kidney. Combined transcriptomic and metabolomic data demonstrated that MWWE exposure induced perturbations of metabolism, including lipid, nucleotide, amino acid, and energy metabolism. Furthermore, dysregulation of signal transduction processes were also identified based on differentially expressed genes. These results suggested that chronic exposure to MWWE could induce hepatotoxicity and nephrotoxicity in mice and omic approaches are of practical value to evaluate the complex toxicity of MWWE.

Hippocampal damage and alterations of inflammatory cytokine expression in mice caused by exposure to cerium chloride

Rare earth element (REE) exposure has been shown to induce central nerve system intoxication, but the molecular mechanisms by which this occurs are poorly understood. In this study, cerium (Ce), in the form of CeCl3, was administered by way of gavage to mice for 90 consecutive days, and cytokine expression, associated with neuroinflammation of hippocampus, as well as spatial memory were increased in mice. Significant Ce accumulation in hippocampus, which led to neuroinflammation and decreased spatial memory of mice, was observed. Furthermore, CeCl3 remarkably increased levels of Toll-like receptors 2 and 4, tumor necrosis factor-α, nucleic IκB kinase, factor-κB-inducible kinase, nucleic factor-κB, and p52 and p65 expression as well as significantly decreased levels of IκB and interleukin-2 expression. These results showed that neuroinflammation and damaged hippocampal function may be associated with CeCl3-induced neuerotoxicity. Our findings suggest the need for workers and consumers to exercise caution when handling REEs.

Gene-expression changes in cerium chloride-induced injury of mouse hippocampus

Cerium is widely used in many aspects of modern society, including agriculture, industry and medicine. It has been demonstrated to enter the ecological environment, is then transferred to humans through food chains, and causes toxic actions in several organs including the brain of animals. However, the neurotoxic molecular mechanisms are not clearly understood. In this study, mice were exposed to 0.5, 1, and 2 mg/kg BW cerium chloride (CeCl(3)) for 90 consecutive days, and their learning and memory ability as well as hippocampal gene expression profile were investigated. Our findings suggested that exposure to CeCl(3) led to hippocampal lesions, apoptosis, oxidative stress and impairment of spatial recognition memory. Furthermore, microarray data showed marked alterations in the expression of 154 genes involved in learning and memory, immunity and inflammation, signal transduction, apoptosis and response to stress in the 2 mg/kg CeCl(3) exposed hippocampi. Specifically, the significant up-regulation of Axud1, Cdc37, and Ube2v1 caused severe apoptosis, and great suppression of Adcy8, Fos, and Slc5a7 expression led to impairment of mouse cognitive ability. Therefore, Axud1, Cdc37, Ube2v1, Adcy8, Fos, and Slc5a7 may be potential biomarkers of hippocampal toxicity caused by CeCl3 exposure.

Organ histopathological changes and its function damage in mice following long-term exposure to lanthanides chloride

Due to increasing applications of lanthanides (Ln) in industry and daily life, numerous studies confirmed that Ln exposure may result in organ damages in mice and rats, while very few studies focused on several organs damages simultaneously. In order to compare the toxicity of Ln on organs, mice were exposed to LaCl(3), CeCl(3), and NdCl(3) of a dose of 20 mg/kg body weight for consecutive 60 days, respectively, then histopathological changes of liver, kidney, and heart, and their function were investigated. The results showed that long-term exposure to Ln caused cell necrosis and basophilia of liver, ambiguity of renal tubule architecture, congestion of blood vessel and capillary of kidney, and heart hemorrhage. The histopathological changes of liver, kidney, and heart in mice caused by Ce(3+) was most severe; the effect by Nd(3+) was slighter than Ce(3+) but more severe than La(3+). The assay of serum biochemical parameters suggested that Ln exposure severely impaired the functions of liver, kidney, and myocardium in mice. These findings suggested that long-term exposure to Ln resulted in histopathological changes of liver, kidney, and heart, and their function damages. Therefore, we thought that long-term application of the products containing Ln on human should be cautious.

The toxicological effects in brain of mice following exposure to cerium chloride

Cerium (Ce) compounds are now widely applied in medicine, agriculture, animal breeding, and daily life; however, the effects of Ce on human body, especially on the central nervous system, are still unclear. In order to investigate whether Ce exposure cause neurotoxicological effects, ICR mice were exposed to CeCl(3) through intragastric administration at 0, 2, 10, and 20 mg/kg body weight doses everyday for 60 days. The behaviors of spatial recognition memory, brain histopathology, the brain elements and neurochemicals, as well as enzymes activities in mice were determined. The Y-maze test showed that CeCl(3) exposure could significantly impair the behaviors of spatial recognition memory. Specifically, in these Ln(3+)-treated mice, the contents of Ca, Mg, Na, K, Fe, and Zn in brain were significantly altered, the activities of Na(+)/K(+)-ATPase, Ca(2+)-ATPase, Ca(2+)/Mg(2+)-ATPase, acetylcholine esterase, and nitric oxide synthase were significantly inhibited; monoamines neurotransmitters such as norepinephrine, dopamine, and 5-hydroxytryptamine were significantly decreased, while the contents of acetylcholine, glutamate, and nitric oxide were significantly increased. These results indicated that CeCl(3) exposure could impair the learning ability, which is attributed to the disturbance of the homeostasis of trace elements, enzymes, and neurotransmitter systems in the mouse brain. Therefore, our study aroused the attention of Ln application and long-term exposure effects.

The impairment of liver DNA conformation and liver apoptosis of mice caused by CeCl3

Cerium (Ce) was shown to cause various toxic effects both in rats and mice; however, the molecular mechanism by which Ce exert theirs toxicity is still understood. In this report, the impairment of liver DNA conformation and liver apoptosis of mice caused by CeCl(3) was studied in vivo using inductively coupled plasma-mass spectrometry, various spectral methods, gel electrophoresis, and transmission electron micrograph. We found that the coefficients of liver to body weight of the mice treated with CeCl(3) were significantly increased. Ce(3+) could be significantly accumulated in the liver, and it insert itself into DNA base pairs and/or bind to DNA nucleotide, and alter the conformation of DNA. Furthermore, the evaluation by gel electrophoresis and transmission electron micrograph showed that higher dose of Ce(3+) could cause DNA cleavage and hepatocyte apoptosis in mice. Therefore, our study aroused the attention of Ce application and exposure effects especially on human liver for long-term and low-dose treatment.

Splenocyte apoptotic pathway in mice following oral exposure to cerium trichloride

With their widespread application in agriculture, industry, culture, medicine, and daily life, lanthanide compounds are being brought into the ecological environment and human body through food chains. It is important to know the acute and chronic effects of lanthanides on the environment, nature balance, and the human body after their entry into bodies and the environment. Lanthanides have been demonstrated to cause spleen apoptosis and decreased immunity of mice, but very little is known about the molecular aspects of these mechanism. In order to understand the spleen apoptotic mechanism induced by intragastric administration of 2, 10 and 20 mg kg(-1) body weight CeCl(3) for consecutive 60 d, we investigated the cerium accumulation, apoptosis, the expression levels of the apoptosis-related cytokines into apoptosis-related genes and proteins. The results demonstrated that cerium had obvious accumulation in the mouse spleen, leading to the significant increase of the spleen indices and splenocyte apoptosis. Furthermore, CeCl(3) could effectively activate caspase-3 and -9, decrease the Bcl-2 the levels of gene and protein, and increase the levels of Bax, and cytochrome c genes and their protein expressions, and promote reactive oxygen species production. It implied CeCl(3)-induced apoptosis in the mouse spleen via intrinsic pathway. Our findings suggest the need for great caution to handle the lanthanides for workers and consumers.