Cadmium inhibits the electron transfer chain and induces reactive oxygen species

Cadmium induces GAPDH- and- MDH mediated delayed cell aging and dysfunction in Candida tropicalis 3Aer

Eukaryotes employ various mechanisms to survive environmental stress conditions. Multicellular organisms eliminate permanently damaged cells by apoptosis, while unicellular eukaryotes like yeast react by decelerating cell aging. In the present study, transcriptomic and proteomic approaches were employed to elucidate the underlying mechanism of delayed apoptosis. Our findings suggest that Candida tropicalis 3Aer has a set of tightly controlled genes that are activated under Cd⁺² exposition. Acute exposure to Cd⁺² halts the cell cycle at the G₂/M phase checkpoint and activates multiple cytoplasmic proteins that overcome effects of Cd⁺²-induced reactive oxygen species. Prolonged Cd⁺² stress damages DNA and initiates GAPDH amyloid formation. This is the first report that Cd⁺² challenge initiates dynamic redistribution of GAPDH and MDH and alters various metabolic pathways including the pentose phosphate pathway. In conclusion, the intracellular redistribution of GAPDH and MDH induced by prolonged cadmium stress modulates various cellular reactions, which facilitate delayed aging in the yeast cell.

The footprints of mitochondrial impairment and cellular energy crisis in the pathogenesis of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and Fanconi's syndrome: A comprehensive review

Fanconi's Syndrome (FS) is a disorder characterized by impaired renal proximal tubule function. FS is associated with a vast defect in the renal reabsorption of several chemicals. Inherited and/or acquired conditions seem to be connected with FS. Several xenobiotics including many pharmaceuticals are capable of inducing FS and nephrotoxicity. Although the pathological state of FS is well described, the exact underlying etiology and cellular mechanism(s) of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and FS are not elucidated. Constant and high dependence of the renal reabsorption process to energy (ATP) makes mitochondrial dysfunction as a pivotal mechanism which could be involved in the pathogenesis of FS. The current review focuses on the footprints of mitochondrial impairment in the etiology of xenobiotics-induced FS. Moreover, the importance of mitochondria protecting agents and their preventive/therapeutic capability against FS is highlighted. The information collected in this review may provide significant clues to new therapeutic interventions aimed at minimizing xenobiotics-induced renal injury, serum electrolytes imbalance, and FS.

Gender Differences in Cardiac Remodeling Induced by a High-Fat Diet and Lifelong, Low-Dose Cadmium Exposure

Childhood obesity, which is prevalent in developed countries, is a metabolic risk factor for cardiovascular disease. Cadmium (Cd), a ubiquitous environmental toxic metal, also has deleterious effects on the cardiovascular system. However, the combined effects of a high-fat diet (HFD) and lifelong, low-dose Cd exposure on cardiac remodeling remain unclear. This study aims to determine the effects of combined HFD and Cd exposure on cardiac remodeling, as well as gender-specific differences in the response. C57BL/6J mice were exposed to Cd at a low dose (L-Cd, 0.5 ppm) or high dose (H-Cd, 5 ppm) via drinking water from conception to sacrifice. After being weaned, the offspring mice were fed with a HFD (42% kcal from fat) for an additional 10 weeks. H-Cd exposure significantly increased Cd accumulation in the hearts of both parents and their offspring; a HFD showed no added effects on cardiac Cd content. H-Cd exposure increased cardiac metallothionein protein levels only in female mice, regardless of dietary intake. Histological analysis revealed that H-Cd exposure combined with a HFD induced cardiac hypertrophy and fibrosis only in female mice. This was further supported by elevated expression of ANP and COL1A1 protein levels along with COL1A1, COL1A2, and COL3A1 mRNA levels. Profibrotic markers PAI-1, CTGF, and FN were also elevated in HFD/H-Cd-exposed female mice. Levels of the oxidative stress marker 3-NT significantly increased in the hearts of HFD-fed female mice, whereas Cd exposure showed no additional effects. Of all the antioxidant markers examined, levels of CAT significantly increased in mice fed a HFD, regardless of gender and Cd exposure. In summary, a HFD combined with lifelong, low-dose Cd exposure induces cardiac hypertrophy and fibrosis in female but not male mice, a response that is independent of oxidative stress.

Limited oxidative stress in common carp (Cyprinus carpio, L., 1758) exposed to a sublethal tertiary (Cu, Cd and Zn) metal mixture

Analyzing effects of metal mixtures is important to obtain a realistic understanding of the impact of mixed stress in natural ecosystems. The impact of a one-week exposure to a sublethal metal mixture containing copper (4.8 μg/L), cadmium (2.9 μg/L) and zinc (206.8 μg/L) was evaluated in the common carp (Cyprinus carpio). To explore whether this exposure induced oxidative stress or whether defense mechanisms were sufficiently fitting to prevent oxidative stress, indicators of apoptosis (expression of caspase 9 [CASP] gene) and of oxidative stress (malondialdehyde [MDA] level and xanthine oxidase [XO] activity) were measured in liver and gills, as well as activities and gene expression of enzymes involved in antioxidant defense (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GPx], glutathione reductase [GR] and glutathione-S-transferase [GST]). The total antioxidative capacity (T-AOC) was also quantified. No proof of oxidative stress was found in either tissue but there was indication of apoptosis in the liver. CAT, GPx, GR and GST total activities were reduced after 7 days, suggesting a potential decrease of glutathione levels and risk of increased free radicals if the exposure would have lasted longer. There were no major changes in the total activities of antioxidant enzymes in the gills, but the relative expression of the genes coding for CAT and GR were triggered, suggesting a response at the transcription level. These results indicate that C. carpio is well equipped to handle these levels of metal pollution, at least during short term exposure.

Specificity of the Metallothionein-1 Response by Cadmium-Exposed Normal Human Urothelial Cells

Occupational and environmental exposure to cadmium is associated with the development of urothelial cancer. The metallothionein (MT) family of genes encodes proteins that sequester metal ions and modulate physiological processes, including zinc homeostasis. Little is known about the selectivity of expression of the different MT isoforms. Here, we examined the effect of cadmium exposure on MT gene and isoform expression by normal human urothelial (NHU) cell cultures. Baseline and cadmium-induced MT gene expression was characterized by next-generation sequencing and RT-PCR; protein expression was assessed by Western blotting using isoform-specific antibodies. Expression of the zinc transporter-1 (SLC30A1) gene was also assessed. NHU cells displayed transcription of MT-2A, but neither MT-3 nor MT-4 genes. Most striking was a highly inducer-specific expression of MT-1 genes, with cadmium inducing transcription of MT-1A, MT-1G, MT-1H, and MT-1M. Whereas MT-1G was also induced by zinc and nickel ions and MT-1H by iron, both MT-1A and MT-1M were highly cadmium-specific, which was confirmed for protein using isoform-specific antibodies. Protein but not transcript endured post-exposure, probably reflecting sequestration. SLC30A1 transcription was also affected by cadmium ion exposure, potentially reflecting perturbation of intracellular zinc homeostasis. We conclude that human urothelium displays a highly inductive profile of MT-1 gene expression, with two isoforms identified as highly specific to cadmium, providing candidate transcript and long-lived protein biomarkers of cadmium exposure.

The Metallome of Lung Cancer and its Potential Use as Biomarker

Carcinogenesis is a very complex process in which metals have been found to be critically involved. In this sense, a disturbed redox status and metal dyshomeostasis take place during the onset and progression of cancer, and it is well-known that trace elements participate in the activation or inhibition of enzymatic reactions and metalloproteins, in which they usually participate as cofactors. Until now, the role of metals in cancer have been studied as an effect, establishing that cancer onset and progression affects the disturbance of the natural chemical form of the essential elements in the metabolism. However, it has also been studied as a cause, giving insights related to the high exposure of metals giving a place to the carcinogenic process. On the other hand, the chemical species of the metal or metallobiomolecule is very important, since it finally affects the biological activity or the toxicological potential of the element and their mobility across different biological compartments. Moreover, the importance of metal homeostasis and metals interactions in biology has also been demonstrated, and the ratios between some elements were found to be different in cancer patients; however, the interplay of elements is rarely reported. This review focuses on the critical role of metals in lung cancer, which is one of the most insidious forms of cancer, with special attention to the analytical approaches and pitfalls to extract metals and their species from tissues and biofluids, determining the ratios of metals, obtaining classification profiles, and finally defining the metallome of lung cancer.

Roflumilast, a phosphodiesterase 4 inhibitor, attenuates cadmium-induced renal toxicity via modulation of NF-κB activation and induction of NQO1 in rats

Objective:

In the present study, the protective effect of Roflumilast (ROF, a selective phosphodiesterase (PDE-4) inhibitor) was investigated against cadmium (Cd)-induced nephrotoxicity in rats.

Methods:

A total of 24 rats were selected and randomly divided into four groups ( n = 6). Group 1 served as the control; groups 2–4 administered with CdCl2 (3 mg/kg, i.p.) for 7 days; groups 3 and 4 were co-administered with ROF in doses of 0.5 and 1.5 mg/kg, orally for 7 consecutive days. Nephrotoxicity was evaluated by measuring urine volume, urea and creatinine levels in urine and serum. Oxidative stress was confirmed by measuring malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) levels in kidney tissue followed by histopathological studies.

Results:

CdCl2 administration results in a significant ( p < 0.01) decrease in urine volume, urea, and creatinine levels in urine, as well as GSH, SOD, and CAT levels in renal tissue. In addition, Cd also produced significantly increased ( p < 0.01) urea and creatinine levels in serum and TBARS levels in renal tissues. Rats treated with ROF significantly ( p < 0.01) restore the altered levels of kidney injury markers, nonenzymatic antioxidant, as well as depleted enzymes in dose-dependent manner. An increased expression of NF-κB p65 and decreased expression of GST and NQO1 in the Cd only treated group were significantly reversed by high dose of ROF (1.5 mg/kg). Histopathological changes were also ameliorated by ROF administration in Cd-treated groups.

Conclusion:

In conclusion, ROF treatment showed protective effect against renal damage and increased oxidative stress induced by Cd administration.

Physiological and biochemical effect of silver on the aquatic plant Lemna gibba L.: Evaluation of commercially available product containing colloidal silver

This paper aims to evaluate the effects of a product containing colloidal silver in the aquatic environment, using duckweed Lemna gibba as a model plant. Therefore, growth parameters, photosynthetic pigments content and protein content as physiological indices were evaluated. Changes in the content of non-enzymatic antioxidants and activity of several antioxidant enzymes, alongside with the accumulation of hydrogen peroxide and lipid peroxidation end-products were assessed to explore the potential of colloidal silver to induce oxidative stress. The commercially available colloidal silver product contained a primary soluble form of silver. The treatment with colloidal silver resulted in significant physiological and biochemical changes in L. gibba plants and a consequent reduction of growth. Accumulation of silver caused altered nutrient balance in the plants as well as a significant decrease in photosynthetic pigments content and protein concentration. The antioxidative response of L. gibba plants to treatment with colloidal silver was inadequate to protect the plants from oxidative stress caused by metal accumulation. Silver caused concentration-dependent and time-dependent hydrogen peroxide accumulation as well as the elevation of lipid peroxidation levels in L. gibba plants. The use of commercially available products containing colloidal silver, and consequent accumulation of silver, both ionic and nanoparticle form in the environment, represents a potential source of toxicity to primary producers in the aquatic ecosystem.

Exposure to environmentally relevant cadmium concentrations negatively impacts early life stages of channel catfish (Ictalurus punctatus)

Cadmium is a persistent contaminant of surface waters. The effects of cadmium on early life stages of fish are not well understood, although they are often disproportionately affected by contaminants. The objectives of this study were to examine effects of chronic exposure to environmentally relevant concentrations on growth, development, cellular stress, and glucose metabolism of channel catfish, Ictalurus punctatus. Eggs were wet-fertilized in treatment water at concentrations of 0.4 (control), 2.2 (low), or 8.5 (high) μg L^-1 and monitored through swim-up, black fry stage. Eggs and fry accumulated cadmium dose-dependently. Fertilization rates were unaffected, yet hatch rate was significantly reduced in the high treatment. Survival to black fry and overall size and condition factor were not affected; however, differences in yolk sac size, and presumably energetics of yolk fry, was detected. Physiological pathways were also affected, demonstrated by altered gene expression, most notably in genes related to carbohydrate metabolism. Elevated expression of HK and G6PD, rather than G6P and GADPH, suggests glucose may be shunted towards the pentose-phosphate pathway. Overall, observations indicate cadmium negatively affects development in early life stages of channel catfish, which could lead to shifts in population structure and life history patterns in exposed populations of wild fish.

The effect of α-tocopherol and dithiothreitol in ameliorating emamectin benzoate cytotoxicity in human K562 cells involving the modulation of ROS accumulation and NF-κB signaling

Emamectin benzoate (EMB) toxicity contributes a potential risk to environment and human health. To investigate the effect of α-tocopherol (VitE) and dithiothreitol (DTT) in ameliorating EMB-induced cytotoxicity in human K562 cells, in vitro cultured human K562 cells were incubated with different concentrations of EMB in supplement with VitE and DTT when the cells were in the logarithmic phase. Next, the cell growth inhibition was evaluated using the MTT assay and cellular morphology observation. Reactive oxygen species (ROS) production was monitored using DCFH-DA probe and NF-κB signaling was determined using Western blotting. The results demonstrated that treatment with EMB (time- and concentration-dependent) showed significantly greater inhibition on K562 cell viability, heavier chromatin condensation and DNA fragmentation, and stronger suppression of NF-κB/p105 and p65/RelA expression of K562 cells than the control group (p < 0.01). The supplementation of VitE or DTT could help protect K562 cells against EMB-induced cytotoxicity by improving cell viability, preventing ROS accumulation and up-regulating NF-κB signaling through their ameliorating effects against oxidative stress induced by EMB. VitE had a stronger synergistic effect in limiting EMB cytotoxicity than DTT. Our findings indicate that VitE and DTT are potent antioxidants for human K562 cells, offering a promising means of ameliorating EMB cytotoxicity.

Emerging pathways to neurodegeneration: Dissecting the critical molecular mechanisms in Alzheimer's disease, Parkinson's disease

Neurodegenerative diseases are usually sporadic in nature and commonly influenced by a wide range of genetic, life style and environmental factors. A unifying feature of Alzheimer's disease (AD) and Parkinson's disease (PD) is the abnormal accumulation and processing of mutant or damaged intra and extracellular proteins; this leads to neuronal vulnerability and dysfunction in the brain. Through a detailed review of ubiquitin proteasome, mRNA splicing, mitochondrial dysfunction, and oxidative stress pathway interrelation on neurodegeneration can improve the understanding of the disease mechanism. The identified pathways common to AD and PD nominate promising new targets for further studies, and as well as biomarkers. These insights suggested would likely provide major stimuli for developing unified treatment approaches to combat neurodegeneration. More broadly, pathways can serve as vehicles for integrating findings from diverse studies of neurodegeneration. The evidence examined in this review provides a brief overview of the current literature on significant pathways in promoting in AD, PD. Additionally, these insights suggest that biomarkers and treatment strategies may require simultaneous targeting of multiple components.

Body size-dependent interspecific tolerance to cadmium and their molecular responses in the marine rotifer Brachionus spp

Although several studies have reported on different interspecific sensitivities in response to various toxicants, the response mechanisms are still poorly understood. Here, we investigate the interspecific toxicity of cadmium (Cd) and its mechanism using three marine rotifer Brachionus spp. that are distinguishable by body size, which is considered the most significant indicator of phenotypic difference. The body sizes of B. plicatilis, B. koreanus, and B. rotundiformis are significantly different throughout their life cycles (egg, neonate, and adult), with the smaller rotifer exhibiting higher sensitivity to Cd. To investigate the mechanisms that result in body size-dependent tolerance to Cd, metabolic and Cd bioaccumulation rates were investigated. Both rates have shown a significant correlation with body size, indicating that body size and its variables are important factors in determining Cd tolerance in Brachionus spp. In addition, similar patterns that further explain body size-dependent tolerance are shown in the phosphorylation status of mitogen-activated protein kinases, reactive oxygen species level, and antioxidant enzymatic activities. Our study provides valuable insight into size- and species-dependent toxicity mechanisms of species in the same genus.

The Chronic Effects of Copper and Cadmium on Life History Traits Across Cladocera Species: A Meta-analysis

The effect of sublethal concentrations of heavy metals on cladoceran growth and reproduction is a cornerstone of modern ecotoxicology. However, the literature contains assays across numerous concentrations, on numerous species and genotypes, and conditions are far from consistent. We undertook a systematic review of the sublethal effects of copper and cadmium concentrations on Cladocera spp. life history (reproduction, maturation age, and somatic growth rate). Using meta-analysis, we tested the hypothesis that the effects of increasing Cu and Cd concentrations on traits may vary by species. We also evaluated where possible whether the effect of metal concentrations on traits vary by water hardness, exposure duration, or whether the metals were delivered in aqueous solution or via food. We surveyed > 200 papers, resulting in a set of 32 experimental studies representing 446 trials where the results were presented compared with Daphnia magna-the most commonly assayed species. We found qualitatively similar effects of Cu and Cd on life history traits that included reduction in reproduction and somatic growth rate and delay of maturation. Cladocera species showed marked variations in their susceptibility to metals, and D. magna was found to be the least sensitive species to sublethal changes in reproduction. The effects were largely consistent for aqueous vs. dietary food. Water hardness, where data were available, had no detectable effect. Available data indicate that exposure duration had no effect on the toxicity of Cu but did for D. magna reproductive response to Cd. Our study highlights the importance of including species identity when considering toxicological testing and regulation development.

Impairment of Mitochondrial-Nuclear Cross Talk in Lymphocytes Exposed to Landfill Leachate

Landfill leachate, a complex mixture of different solid waste compounds, is widely known to possess toxic properties. However, the fundamental molecular mechanisms engaged with landfill leachate exposure inducing cellular and sub-cellular ramifications are not well explicated. Therefore, we aim to examine the potential of leachate to impair mitochondrial machinery and its associated mechanisms in human peripheral blood lymphocytes. On assessment, the significant increase in the dichlorofluorescein (DCF) fluorescence, accumulation of 8-Oxo-2'-deoxyguanosine (8-oxo-dG), and levels of nuclear factor erythroid 2-related factor 2 (Nrf-2) strongly indicated the ability of the leachate to induce a pro-oxidant state inside the cell. The decrease in the mitochondrial membrane potential and alterations in the mitochondrial genome observed in leachate-exposed cells further suggested the disturbances in mitochondrial machinery. Moreover, these mitochondrial-associated redox imbalances were accompanied by the increased level of NF-κβ, pro-inflammatory cytokines, and DNA damage. In addition, the higher DNA fragmentation, release of nucleosomes, levels of polyadenosine diphosphate ADP-ribose polymerase (PARP), and activity of caspase-3 suggested the involvement of mitochondrial mediated apoptosis in leachate exposed cells. These observations were accompanied by the low proliferative index of the exposed cells. Conclusively, our results clearly indicate the ability of landfill leachate to disturb mitochondrial redox homeostasis, which might be a probable source for the immunotoxic consequences leading to plausible patho-physiological conditions in humans susceptible to such environmental exposures.

Aqueous bark extract of Terminalia arjuna protects against cadmium-induced hepatic and cardiac injuries in male Wistar rats through antioxidative mechanisms

Cadmium (Cd) is one of the most ubiquitous toxic heavy metal in the environment. The present study was conducted to evaluate the protective role of aqueous bark extract of Terminalia arjuna (TA) against Cd induced oxidative damage in hepatic and cardiac tissues as the TA bark extract has folkloric medicinal use in the treatment of various hepatic and cardiac disorders. Male Wistar rats were divided into 4 groups. The control group was treated with normal saline as the vehicle; the second group orally administered with TA (20 mg/kg bw) daily for 15 days; the third group injected with Cd-acetate (0.44 mg/kg bw, s.c.) every alternate day for a period of 15 days; and the fourth group was administered with TA, 60 min prior to Cd treatment. The biomarkers of organ damage were significantly increased in the Cd treated groups. Besides, a significant alteration in the tissue levels of biomarkers of oxidative stress, the activities and the levels of antioxidant enzymes was observed following treatment with Cd. Additionally, some of the enzymes were found to be inhibited uncompetitively by Cd when tested in an in vitro system. Furthermore, evidence gathered from studies on the histological parameters and mitochondrial membrane potential in both the tissues argue in favour of the possible protective role of TA against Cd induced damage. Finally, gas chromatography-mass spectrometry revealed the presence of eight major bioactive phytochemicals in aqueous bark extract of TA having potent free radical scavenging property. The results indicate that the extract could protect hepatic and cardiac tissues against Cd-induced oxidative stress mediated damages through antioxidant mechanism(s).

High-throughput gene expression in soil invertebrate embryos - Mechanisms of Cd toxicity in Enchytraeus crypticus

Gene expression can vary with the organisms' life stage. It is known that embryos can be more sensitive to toxicant exposure, as previously demonstrated for Enchytraeus crypticus (Oligochaeta) exposed to cadmium (Cd), known to cause embryotoxicity and hatching delay. It was shown that Ca enters embryos via the L-type Ca channels in the cocoon membrane, this being affected in Cd exposed embryos (Cd-Ca competition is well-known). In the present study, the embryotoxic mechanisms of Cd were studied via high-throughput gene expression for E. crypticus. Cocoons (1-2 days old), instead of the adult organism, were exposed in Cd spiked LUFA 2.2 soil during 1 day. Results showed that Cd affected Ca homeostasis which is implicated in several other molecular processes. Several of the major modulators of Cd toxicity (e.g., impaired gene expression, cell cycle arrest, DNA and mitochondrial damage) were identified in the embryos showing its relevancy as a model in ecotoxicogenomics. The draft Adverse Outcome Pathway was improved. Previously was hypothesized that gene regulation mechanisms were activated to synthesize more Ca channel proteins - this was confirmed here. Further, novel evidences were that, besides the extracellular competition, Cd competes intracellularly which causes a reduction in Ca efflux, and potentiates Cd embryotoxicity.

Effects of cobalt and chromium ions on oxidative stress and energy metabolism in macrophages in vitro

Cobalt and chromium ions released from cobalt-chromium-molybdenum (CoCrMo)-based implants are a potential health concern, especially since both ions have been shown to induce oxidative stress in macrophages, the predominant immune cells in periprosthetic tissues. Ions of other transition metals (Cd, Ni) have been reported to inhibit the activity of mitochondrial enzymes in the electron transport chain. However, the effects of Co and Cr ions on the energy metabolism of macrophages remain largely unknown. The objective of the present study was to analyze the effects of Co²⁺ and Cr³⁺ on oxidative stress and energy metabolism in macrophages in vitro. RAW 264.7 murine macrophages were exposed to 6-18 ppm Co²⁺ or 50-150 ppm Cr³⁺ . Results showed a significant increase in two markers of oxidative stress, reactive oxygen species level and protein carbonyl content, with increasing concentrations of Co²⁺ , but not with Cr³⁺ . In addition, oxygen consumption rates (OCR; measured using an extracellular flux analyzer) showed significant decreases in both mitochondrial respiration and non-mitochondrial oxygen consumption with increasing concentrations of Co²⁺ , but not with Cr³⁺ . OCR results further showed that Co²⁺ , but not Cr³⁺ , induced mitochondrial dysfunction, including a decrease in oxidative phosphorylation capacity. Overall, this study suggests that mitochondrial dysfunction may contribute to Co²⁺ -induced oxidative stress in macrophages, and thereby to the inflammatory response observed in periprosthetic tissues. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3178-3187, 2018.

Respiratory complex II in mitochondrial dysfunction-mediated cytotoxicity: Insight from cadmium

In the present work we studied action of several inhibitors of respiratory complex II (CII) of mitochondrial electron transport chain, namely malonate and thenoyltrifluoroacetone (TTFA) on Cd²⁺-induced toxicity and cell mortality, using two rat cell lines, pheochromocytoma PC12 and ascites hepatoma AS-30D and isolated rat liver mitochondria (RLM). It was shown that malonate, an endogenous competitive inhibitor of dicarboxylate-binding site of CII, restored in part RLM respiratory function disturbed by Cd²⁺. In particular, malonate increased both phosphorylating and maximally uncoupled respiration rates in KCl medium in the presence of CI substrates as well as palliated changes in basal and resting state respiration rates produced by the heavy metal on the mitochondria energized by CI or CII substrates. Notably, malonate enhanced Cd²⁺-induced swelling of the mitochondria energized by CI substrates in KCl and, in a much lesser extent and at higher [Cd²⁺], in sucrose media but did not influence on the Cd²⁺ effects in NaCl medium. Besides, malonate did not affect swelling in sucrose media of RLM energized by CIV substrates under using of Cd²⁺ or Ca²⁺ whereas it strongly increased the mitochondrial swelling produced by selenite. In addition, malonate produced some protection against Cd²⁺-promoted necrotic death of AS-30D and PC12 cells and reduced intracellular reactive oxygen species (ROS) formation evoked by Cd²⁺ in PC12 cells. Importantly, TTFA, an irreversible competitive inhibitor of Q-binding site of CII, per se induced apoptosis of AS-30D cells which was inhibited by co-treatment with Cd²⁺ as well as decreased the Cd²⁺-enhanced intracellular ROS formation. In turn, decylubiquinone (dUb) at low μM concentrations did not protect AS-30D cells against the Cd²⁺-induced necrosis and enhanced the Cd²⁺-induced apoptosis of the cells. High μM concentrations of dUb were highly toxic for the cells. As consequence, the findings give new evidence indicative of critical involvement of CII in mechanism(s) of Cd²⁺-produced cytotoxicity and support the notion on CII as a perspective pharmacological target in mitochondria dysfunction-mediated conditions and diseases.

Association of Cadmium and Lead Exposure With the Incidence of Contrast Sensitivity Impairment Among Middle-aged Adults

Importance

Contrast sensitivity (CS) is an important indicator of visual function that affects daily life, including mobility, visually intensive tasks, safety, and autonomy. Understanding the risk factors for CS impairment could prevent decreases in visual function.

Objective

To determine the incidence of and factors associated with CS impairment in a large cohort.

Design, Setting, and Participants

The Beaver Dam Offspring Study is an ongoing longitudinal cohort study of aging involving adults in Beaver Dam, Wisconsin. Participants who were free of CS impairment in both eyes at baseline were included (N = 1983). Baseline data collection occurred from June 8, 2005, through August 4, 2008, when the participants ranged from 21 to 84 years of age. Two follow-up examinations occurred at 5-year intervals: one was conducted between July 12, 2010, and March 21, 2013, and the other between July 1, 2015, and November 13, 2017. Data analysis was performed from November 27, 2017, to February 27, 2018.

Main Outcomes and Measures

Contrast sensitivity testing was conducted with Pelli-Robson letter sensitivity charts, and incident impairment was defined as a log CS score less than 1.55 in either eye at any follow-up examination. Cadmium and lead levels were measured in whole blood with inductively coupled plasma mass spectrometry. Associations between baseline characteristics and CS impairment incidence were examined using Cox proportional hazard models and quantified as hazard ratios (HRs) with 95% CI.

Results

Of the 1983 participants included, 1028 (51.8%) were female and 955 (48.2%) were male, with a mean (SD) age of 48 (9.3) years. The 10-year cumulative incidence of CS impairment was 24.8% (95% CI, 22.9-26.8), similar in women (24.9%) and men (24.6%), and highest in the oldest age group (65-84 years) at 66.3%. In multivariable models, cadmium level in the highest quintile (HR, 1.35; 95% CI, 1.02-1.78), older age (HR, 1.36; 95% CI, 1.25-1.47), larger waist circumference (HR, 1.06; 95% CI, 1.01-1.11), and more plaque sites (1-3 sites: HR, 1.43; 95% CI, 1.07-1.92; 4-6 sites: HR, 2.75; 95% CI, 1.26-6.05) were among the factors associated with increased risk, while male sex (HR, 0.77; 95% CI, 0.60-0.98) and any alcohol consumption (HR, 0.61; 95% CI, 0.43-0.88) were associated with decreased risk. Results were similar when smoking status replaced cadmium exposure in the models. Lead level was not associated with increased risk.

Conclusions and Relevance

This study's findings suggest that incident CS impairment was common in the 10-year follow-up, with cadmium, but not lead, exposure associated with increased risk. The associations of diminished CS with other modifiable risk factors found appear to imply that changes in behavior may reduce future incidence of CS impairment.

Macrophage Rac2 Is Required to Reduce the Severity of Cigarette Smoke-induced Pneumonia

RATIONALE

Cigarette smoking is prevalent in the United States and is the leading cause of preventable diseases. A prominent complication of smoking is an increase in lower respiratory tract infections (LRTIs). Although LRTIs are known to be increased in subjects that smoke, the mechanism(s) by which this occurs is poorly understood.

OBJECTIVES

Determine how cigarette smoke (CS) reduces reactive oxygen species (ROS) production by the phagocytic NOX2 (NADPH oxidase 2), which is essential for innate immunity in lung macrophages.

METHODS

NOX2-derived ROS and Rac2 (Ras-related C3 botulinum toxin substrate 2) activity were determined in BAL cells from wild-type and Rac2-/- mice exposed to CS or cadmium and in BAL cells from subjects that smoke. Host defense to respiratory pathogens was analyzed in mice infected with Streptococcus pneumoniae.

MEASUREMENTS AND MAIN RESULTS

NOX2-derived ROS in BAL cells was reduced in mice exposed to CS via inhibition of the small GTPase Rac2. These mice had greater bacterial burden and increased mortality compared with air-exposed mice. BAL fluid from CS-exposed mice had increased levels of cadmium, which mediated the effect on Rac2. Similar observations were seen in human subjects that smoke. To support the importance of Rac2 in the macrophage immune response, overexpression of constitutively active Rac2 by lentiviral administration increased NOX2-derived ROS, decreased bacterial burden in lung tissue, and increased survival compared with CS-exposed control mice.

CONCLUSIONS

These observations suggest that therapies to maintain Rac2 activity in lung macrophages restore host defense against respiratory pathogens and diminish the prevalence of LRTIs in subjects that smoke.

Do trace metal contamination and parasitism influence the activities of the bioturbating mud shrimp Upogebia cf. pusilla?

Mud shrimp are considered as among the most influential ecosystem engineers in marine soft bottom environments because of their significant bioturbation activity and their high density. These organisms play a key role on the physical structure of sediments through intense sediment reworking activity and also deeply influence geochemical properties of sediments via frequent bioirrigation events. The influence that mud shrimp have on the environment is related to the magnitude of bioturbation processes and subsequently depends on their physiological condition. In natural environments, several factors act together and influence the well-being of organisms. Among them, the deleterious role of parasites on the physiology and the behavior of their host is well established. Aquatic organisms are also subject to pollutants released by anthropogenic activities. However, the effect of both stressors on the fitness and bioturbation activity of mud shrimp has never been investigated yet. We conducted a 14-day ex-situ experiment to evaluate the influence of trace metal contamination (cadmium Cd) and parasitism infestation on the gene expression (molecular endpoint) and sediment reworking activity (behavioral endpoint) of the mud shrimp Upogebia cf. pusilla. At completion, mud shrimp exhibited substantial Cd bioaccumulation, with parasitized organisms showing a significantly lower contaminant burden than unparasitized specimens. Cadmium contamination induces modifications of gene expression in both unparasitized and parasitized organisms. We report an antagonistic effect of both stressors on gene expression, which cannot be fully explained by a lower Cd bioaccumulation. At the behaviour level, parasitism seems to reduce the sediment reworking activity of mud shrimp, while Cd contamination appears to stimulate this activity. This study highlights that the effects of multiple stressors may be quite different from the effects of each stressor considered individually. It should also motivate for more studies evaluating the influence of multiple stressors on different endpoints encompassing various levels of organization.

Selenium and zinc: Two key players against cadmium-induced neuronal toxicity

Cadmium (Cd), a worldwide occupational pollutant, is an extremely toxic heavy metal, capable of damaging several organs, including the brain. Its toxicity has been related to neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. The neurotoxic potential of Cd has been attributed to the changes induced in the brain enzyme network involved in counteracting oxidative stress. On the other hand, it is also known that trace elements, such as zinc (Zn) and selenium (Se), required for optimal brain functions, appears to have beneficial effects on the prevention of Cd intoxication. Based on this protective effect of Zn and Se, we aimed to investigate whether these elements could protect neuronal cells from Cd-induced excitotoxicity. The experiments, firstly carried out on SH-SY5Y catecholaminergic neuroblastoma cell line, demonstrated that the treatment with 10 μM cadmium chloride (CdCl₂) for 24 h caused significant modifications both in terms of oxidative stress and neuronal sprouting, triggered by endoplasmic reticulum (ER) stress. The evaluation of the effectiveness of 50 μM of zinc chloride (ZnCl₂) and 100 nM sodium selenite (Na₂SeO₃) treatments showed that both elements were able to attenuate the Cd-dependent neurotoxicity. However, considering that following induction with retinoic acid (RA), the neuroblastoma cell line undergoes differentiation into a cholinergic neurons, our second aim was to verify the zinc and selenium efficacy also in this neuronal phenotype. Our data clearly demonstrated that, while zinc played a crucial role on neuroprotection against Cd-induced neurotoxicity independently from the cellular phenotype, selenium is ineffective in differentiated cholinergic cells, supporting the notion that the molecular events occurring in differentiated SH-SY5Y cells are critical for the response to specific stimuli.

Review of polyphenol-rich products as potential protective and therapeutic factors against cadmium hepatotoxicity

Recently, the growing attention of the scientific community has been focused on the threat to health created by environmental pollutants, including toxic metals such as cadmium (Cd), and on the need of finding effective ways to prevent and treat the unfavorable health effects of exposure to them. Particularly promising for Cd, and thus arousing the greatest interest, is the possibility of using various ingredients present in plants, including mainly polyphenolic compounds. As the liver is one of the target organs for this toxic metal and disturbances in the proper functioning of this organ have serious consequences for health, the aim of the present review was to discuss the possibility of using polyphenol-rich food products (e.g., chokeberry, black and green tea, blueberry, olive oil, rosemary and ginger) as the strategy in protection from this xenobiotic hepatotoxicity and treatment of this heavy metal-induced liver damage. Owing to the ability of polyphenols to bind ions of Cd and the strong antioxidative potential of these compounds, as well as their abundance in dietary products, it seems to be of high importance to consider the possibility of using polyphenols as potential preventive and therapeutic agents against Cd hepatotoxicity, determined by its strong pro-oxidative properties. Although most of the data on the effectiveness of polyphenols comes from studies in animals, the fact that some of them are derived from experimental models that reflect human exposure to this metal allows us to assume that some polyphenol-rich food products may be promising protective agents against Cd hepatotoxicity in humans.

Anaerobic end-products and mitochondrial parameters as physiological biomarkers to assess the impact of urban pollutants on a key bioturbator

The impact of long-term exposure (6 months) to highly or slightly polluted sediments on the energy metabolism of an ecosystem engineer (the oligochaete Limnodrilus hoffmeisteri) was investigated in laboratory conditions. We evaluated some mitochondrial parameters (respiratory chain activity and ATP production rate) and the accumulation of anaerobic end-products (lactate, alanine, succinate, and propionate). The sediments were collected from stormwater infiltration basins and presented high levels of heavy metals and polycyclic aromatic hydrocarbons (PAHs). These compounds had been drained by the runoff water on impervious surfaces of urban areas during rainfall events. A decrease in the activity of the mitochondrial electron transport chain was observed in worms exposed to the most polluted sediment. Urban contaminants disrupted both aerobic metabolism and mitochondrial functioning, forcing organisms to shift from aerobic to anaerobic metabolism (which is characteristic of a situation of functional hypoxia). Although L. hoffmeisteri is very tolerant to urban pollutants, long-term exposure to high concentrations can cause disruption in mitochondrial activity and therefore energy production. Finally, this study demonstrated that anaerobic end-products could be used as biomarkers to evaluate the impact of a mixture of urban pollutants on invertebrates.

Stone quarrying induces organ dysfunction and oxidative stress in Meriones libycus

Exposure to heavy metal-containing dust arising from stone quarrying may cause severe health problems. The aim of this study was to evaluate the impact of stone quarrying in Riyadh (Saudi Arabia) on the Libyan jird Meriones libycus. Soil samples and jirds were collected from four sites located at different distances from the quarrying area. Soil from the first (500 m away from the quarry) and second (1800 m away) sites showed a significant increase in cadmium (Cd), lead (Pb), nickel (Ni), and vanadium (V) when compared with the reference site (38,000 m away). Jirds at these sites exhibited significant increases in liver, kidney, lung, and fur levels of Cd, Pb, Ni, and V. Serum transaminases, creatinine, and malondialdehyde (MDA) levels were significantly increased in jirds, whereas reduced glutathione (GSH) levels decreased. Liver, kidney, and lung tissues of jirds, collected from the first and second sites, showed significantly increased MDA and decreased GSH levels. Additionally, animals at both sites showed altered hematological parameters and several histopathological changes in their liver, kidney, and lung. Soil and animals at the third site (7300 m away) showed no significant changes. Thus, our study showed the impact and hazardous effects of quarrying on the liver, kidney, lung, and hemogram of M. libycus. These findings can provide scientific evaluation for studying the impact of quarrying on the workers and communities living close to the studied area.

The effect of astaxanthin and cadmium on rat erythrocyte G6PD, 6PGD, GR, and TrxR enzymes activities in vivo and on rat erythrocyte 6PGD enzyme activity in vitro

In this study, the effects of astaxanthin (AST) that belongs to carotenoid family and cadmium (Cd), which is an important heavy metal, on rat erythrocyte G6PD, 6PGD, GR, and TrxR enzyme activities in vivo and on rat erythrocyte 6PGD enzyme activity in vitro were studied. In in vitro studies, 6PGD enzyme was purified from rat erythrocytes with 2',5'-ADP Sepharose4B affinity chromatography. Results showed inhibition of enzyme by Cd at IC₅₀ ; 346.5 μM value and increase of 6PGD enzyme activity by AST. In vivo studies showed an increase in G6PD, 6PGD, and GR enzyme activities (P ˃ 0.05) and no chance in TrxR enzyme activity by AST. Cd ion inhibited G6PD, 6PGD, and GR enzyme activities (P ˂ 0.05) and also decreased TrxR enzyme activity (P ˃ 0.05). AST + Cd group G6PD enzyme activity was statistically low compared with control group (P ˂ 0.05). 6PGD and TrxR enzyme activities decreased without statistical significance (P ˃ 0.05); however, GR enzyme activity increased statistically significantly (P ˂ 0.05).

Oral administration of cadmium depletes intratesticular and epididymal iron levels and inhibits lipid peroxidation in the testis and epididymis of adult rats

Cadmium (Cd)-induced tissue injury depends on the accumulated Cd which differentially affects endogenous iron (Fe). To investigate this, adult rats were treated by oral gavage with Cd (50 mg/kg body wt.) once a week for 15, 30 and 60 days and sacrificed a day after last administration. After the 15th and 30th day of treatment, Cd had no effect on thiobarbituric acid reactive substances (TBARS) and endogenous Fe levels but exhibited anti-androgenic effects (p < 0.05) and caused histological damages. At day 60, Cd was accumulated by 156.30% and 364.77% above control values at concentrations that decreased endogenous Fe levels by 46.41% and 50.31% in the testis and epididymis respectively. The histological damages were characterized by decreased tubular diameter, damage to the epithelium leading to loss of tubular germ cells and absent of spermatozoa in the epididymal lumen. Although myeloperoxidase activities were increased, TBARS levels were found to decrease significantly at day 60 in the serum, testis and epididymis suggesting that the histological damages were not caused by lipid peroxidation. Furthermore, TBARS correlated negatively with Cd in the testis (r = -0.251, p < 0.05) and epididymis (r = -0.286, p < 0.05); Fe correlated positively with TBARS in the testis (r = +0.217, p < 0.05) and Cd correlated negatively with Fe in the testis (r = -0.461, p < 0.05) and epididymis (r = -0.109, p < 0.05). The antioxidant enzymes, superoxide dismutase and glutathione peroxidase were also decreased in the gonads after 60 days Cd treatment. Overall, anti-androgenic effects and histo-pathological changes are early indicators of direct effects of Cd and occur before decrease in TBARS which is secondarily related to the modifying of Fe contents.

Blood lead and cadmium in age related macular degeneration in a Turkish urban population

PURPOSE

To evaluate the blood lead (Pb) and cadmium (Cd) levels in age related macular degeneration (AMD) in a turkish urban population.

METHODS

Blood Pb and Cd levels of 31 AMD patients and 24 age and gender matched controls with no sign of AMD were measured using dual atomic absorption spectrophotometer system (AAS). History of hypertension, diabetes mellitus, cigarette smoking, myocardial infarction and stroke were obtained from all subjects. Degree of AMD was grade 4 according to the Age-Related Eye Disease Study grading system. Median blood Pb and Cd levels were compared by using Students' t-test.

RESULTS

Demographic properties like smoking status, presence of diabetes mellitus or hypertension, cerebrovascular occlusion history, serum cholesterol and lipid levels were not significantly different between groups except history of ischemic heart disease (3.22% vs 25% in AMD and control groups respectively, p = .022). Overall in AMD group blood Pb level was 2.83 ± 0.15 μg/l and it was 2.63 ± 0.23 μg/l in control group (p = .36). The Cd level was 3.25 ± 0.20 μg/l in AMD group and 3.11 ± 0.25 μg/l in control group (p = .67). The mean Pb (2.38 ± 0.88 μg/l vs 2.91 ± 1.37 μg/l for AMD vs control, p = .61) and Cd levels (3.06 ± 1.34 μg/l vs 3.35 ± 1.26 μg/l for AMD vs control, p = .56) in current and previous smokers with AMD were not significantly different from those of the current and previous smokers in control group.

CONCLUSION

Blood Pb and Cd levels which reflect short term exposure were not significantly different in AMD patients and the control group. The difference was not significant either after involvement of previous or current smoker subjects.

Response of antioxidant enzymes to Cd and Pb exposure in water flea Daphnia magna: Differential metal and age - Specific patterns

To investigate oxidative stress responses to cadmium and lead, the freshwater water flea Daphnia magna was exposed to Cd and Pb for 48 h. Following treatment with sub-lethal concentrations, intracellular reactive oxygen species (ROS) levels, as well as modulation of multiple biomarker, such as superoxide dismutase (SOD) activity, glutathione (GSH) contents, glutathione S-transferase (GST) activity, antioxidant enzyme - coding genes (three GST isoforms, glutaredoxin [GRx], glutathione peroxidase [GPx], and thioredoxin [TRx]), and stress-response proteins (heat shock protein 70 [Hsp70] and Hsp90) were examined. The results showed that intracellular ROS level was not changed at 24 h, but reduced at 48 h. Levels of total GSH content were reduced by Cd, but highly induced by Pb. SOD and GST activities were stimulated 48 h after exposure to Cd and Pb. A significant modulation of oxidative stress marker genes was observed after exposure to each element with different expression patterns depending on the metal and developmental stages. In particular, the expression levels of GST-sigma, HSP70, and HSP90 genes were enhanced in Cd - and Pb - exposed neonates. These findings imply that oxidative stress markers appear to be actively involved in cellular protection against metal-induced oxidative stress in D. magna. This study would facilitate the understanding of the molecular response to Cd and Pb exposure in water fleas.

Agaricus blazei Murill Polysaccharides Protect Against Cadmium-Induced Oxidative Stress and Inflammatory Damage in Chicken Spleens

Agaricus blazei Murill polysaccharide (ABP) has exhibited antioxidant and immunoregulatory activity. The aim of this study was to investigate the effect of ABP on cadmium (Cd)-induced antioxidant functions and inflammatory damage in chicken spleens. In this study, groups of 7-day-old chickens were fed with normal saline (0.2 mL single/day), CdCl₂ (140 mg/kg/day), ABP (30 mg/mL, 0.2 mL single/day), and Cd + ABP (140 mg/kg/day + 0.2 mL ABP). Spleens were separated on the 20th, 40th, and 60th day for each group. The Cd contents, expression of melanoma-associated differentiation gene 5 (MDA5) and its downstream signaling molecules (interferon promoter-stimulating factor 1 (IPS-1), transcription factors interferon regulatory factor 3 (IRF3), and nuclear factor kappa-light chain-enhancer of activated B cells (NF-κB)), the content of cytokines (interleukin 1β (IL-1β), interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α) and beta interferon (IFN-β)), protein levels of heat shock proteins (HSPs), levels of malondialdehyde (MDA), activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), and histopathological changes of spleens were detected on the 20th, 40th, and 60th day. The results showed that ABP significantly reduced the accumulation of Cd in the chicken spleens and reduced the expression of MDA5, IPS-1, IRF-3, and NF-κB; their downstream inflammatory cytokines, IL-1β, IL-6, TNF-α, and IFN-β; and the protein levels of HSPs (HSP60, HSP70, and HSP90) in spleens. The activities of antioxidant enzymes (SOD and GSH-Px) significantly increased, and the level of MDA decreased in the ABP + Cd group. The results indicate that ABP has a protective effect on Cd-induced damage in chicken spleens.

Biochemical and transcriptional analyses of cadmium-induced mitochondrial dysfunction and oxidative stress in human osteoblasts

Cadmium (Cd) accumulation is known to occur predominantly in kidney and liver; however, low-level long-term exposure to Cd may also result in bone damage. Few studies have addressed Cd-induced toxicity in osteoblasts, particularly upon cell mitochondrial energy processing and putative associations with oxidative stress in bone. To assess the influence of Cd treatment on mitochondrial function and oxidative status in osteoblast cells, human MG-63 cells were treated with Cd (up to 65 μM) for 24 or 48 h. Intracellular reactive oxygen species (ROS), lipid and protein oxidation and antioxidant defense mechanisms such as total antioxidant activity (TAA) and gene expression of antioxidant enzymes were analyzed. In addition, Cd-induced effects on mitochondrial function were assessed by analyzing the activity of enzymes involved in mitochondrial respiration, membrane potential (ΔΨm), mitochondrial morphology and adenylate energy charge. Treatment with Cd increased oxidative stress, concomitantly with lipid and protein oxidation. Real-time polymerase chain reaction (qRT-PCR) analyses of antioxidant genes catalase (CAT), glutathione peroxidase 1 (GPX1), glutathione S-reductase (GSR), and superoxide dismutase (SOD1 and SOD2) exhibited a trend toward decrease in transcripts in Cd-stressed cells, particularly a downregulation of GSR. Longer treatment with Cd (48 h) resulted in energy charge states significantly below those commonly observed in living cells. Mitochondrial function was affected by ΔΨm reduction. Inhibition of mitochondrial respiratory chain enzymes and citrate synthase also occurred following Cd treatment. In conclusion, Cd induced mitochondrial dysfunction which appeared to be associated with oxidative stress in human osteoblasts.

Disruption of the zinc metabolism in rat fœtal brain after prenatal exposure to cadmium

This study was carried out to investigate the effects of maternal Cd and/or Zn exposure on some parameters of Zn metabolism in fetal brain of Wistar rats. Thus, female controls and other exposed by the oral route during the gestation period to Cd (50 mg CdCl2/L) and/or Zn (ZnCl2 60 mg/L) were used. The male fetuses at age 20 days of gestation (GD20) were sacrificed and their brains were taken for histological, chemical and molecular analysis. Zn depletion was observed in the brains of fetuses issued from mothers exposed to Cd. Histological analysis showed that Cd exposure induces pyknosis in cortical region and CA1 region of the hippocampus compared to controls. Under Cd exposure, we noted an overexpression of the genes coding for membrane transporter involved in the intracellular incorporation of Zn (ZIP6) associated with inhibition of that encoding the transporters involved in the output of the Zn into the extracellular medium (ZnT1 and ZnT3). A decrease in the expression of the gene encoding the neuro-trophic factor (BDNF) associated with overexpression of the encoding the metal regulatory transcription factor 1 (MTF1), factor involved in the homeostasis of Zn, was also noted in Cd group. Interestingly, Zn supply provided a total or partial restauration of the changes induced by the Cd exposure. The depletion of brain Zn contents as well as the modification of the profile of expression of genes encoding membrane Zn transporters, suggest that the toxicity of Cd observed in fetal brain level are mediated, in part, by impairment of Zn metabolism.

Ultrafine particulate matter impairs mitochondrial redox homeostasis and activates phosphatidylinositol 3-kinase mediated DNA damage responses in lymphocytes

Particulate matter (PM), broadly defined as coarse (2.5-10 μm), fine (0.1-2.5 μm) and ultrafine particles (≤0.1 μm), is a major constituent of ambient air pollution. Recent studies have linked PM exposure (coarse and fine particles) with several human diseases including cancer. However, the molecular mechanisms underlying ultrafine PM exposure induced cellular and sub-cellular repercussions are ill-defined. Since mitochondria are one of the major targets of different environmental pollutants, we herein aimed to understand the molecular repercussion of ultrafine PM exposure on mitochondrial machinery in peripheral blood lymphocytes. Upon comparative analysis, a significantly higher DCF fluorescence was observed in ultrafine PM exposed cells that confirmed the strong pro-oxidant nature of these particles. In addition, the depleted activity of antioxidant enzymes, glutathione reductase and superoxide dismutase suggested the strong association of ultrafine PM with oxidative stress. These results further coincided with mitochondrial membrane depolarization, altered mitochondrial respiratory chain enzyme activity and decline in mtDNA copy number. Moreover, the higher accumulation of DNA damage response proteins (γH2AX, pATM, p-p53), suggested that exposure to ultrafine PM induces DNA damage and triggers phosphatidylinositol 3 kinase mediated response pathway. Further, the alterations in mitochondrial machinery and redox balance among ultrafine PM exposed cells were accompanied by a considerably elevated pro-inflammatory cytokine response. Interestingly, the lower apoptosis levels observed in ultrafine particle treated cells suggest the possibility that the marked alterations may lead to the impairment of mitochondrial-nuclear cross talk. Together, our results showed that ultrafine PM, because of their smaller size possesses significant ability to disturb mitochondrial redox homeostasis and activates phosphatidylinositol 3 kinase mediated DNA damage response pathway, an unknown molecular paradigm of ultrafine PM exposure. Our findings also indicate that maneuvering through the mitochondrial function might be a viable, indirect method to modulate lymphocyte homeostasis in air pollution associated immune disorders.

Cadmium Alters the Concentration of Fatty Acids in THP-1 Macrophages

Fatty acid composition of human immune cells influences their function. The aim of this study was to evaluate the effects of known toxicant and immunomodulator, cadmium, at low concentrations on levels of selected fatty acids (FAs) in THP-1 macrophages. The differentiation of THP-1 monocytes into macrophages was achieved by administration of phorbol myristate acetate. Macrophages were incubated with various cadmium chloride (CdCl₂) solutions for 48 h at final concentrations of 5 nM, 20 nM, 200 nM, and 2 μM CdCl₂. Fatty acids were extracted from samples according to the Folch method. The fatty acid levels were determined using gas chromatography. The following fatty acids were analyzed: long-chain saturated fatty acids (SFAs) palmitic acid and stearic acid, very long-chain saturated fatty acid (VLSFA) arachidic acid, monounsaturated fatty acids (MUFAs) palmitoleic acid, oleic acid and vaccenic acid, and n-6 polyunsaturated fatty acids (PUFAs) linoleic acid and arachidonic acid. Treatment of macrophages with very low concentrations of cadmium (5-200 nM) resulted in significant reduction in the levels of arachidic, palmitoleic, oleic, vaccenic, and linoleic acids and significant increase in arachidonic acid levels (following exposure to 5 nM Cd), without significant reduction of palmitic and stearic acid levels. Treatment of macrophages with the highest tested cadmium concentration (2 μM) produced significant reduction in the levels of all examined FAs: SFAs, VLSFA, MUFAs, and PUFAs. In conclusion, cadmium at tested concentrations caused significant alterations in THP-1 macrophage fatty acid levels, disrupting their composition, which might dysregulate fatty acid/lipid metabolism thus affecting macrophage behavior and inflammatory state.

Regulation of autophagy factors by oxidative stress and cardiac enzymes imbalance during arsenic or/and copper induced cardiotoxicity in Gallus gallus

Basal autophagy has an indispensable role in the functioning and maintenance of cardiac geometry under physiological conditions. Recently, increasing evidence has demonstrated that arsenic (As)/copper (Cu) play important roles in the autophagy of the heart. The current study was to evaluate whether oxidative damage by As or/and Cu was correlated with autophagy through the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway in the heart of birds. Arsenic trioxide (30mg/kg) or/and cupric sulfate (300mg/kg) were administered in a basal diet to male Hy-line chickens (one-day-old) for 12 weeks. The results showed that heart weight/body weight ratio decreased in the As + Cu group only at 4, 8 and 12 weeks. Moreover, we observed that As or/and Cu decreased high-density lipoprotein cholesterol (HDL-C) concentrations, increased total cholesterol (T-CHO) concentrations and cardiac enzymes activities in the serum. On the other hand, As or/and Cu significantly reduced the activities of total antioxidant (T-AOC), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px)) along with decreased nonenzymic antioxidant (glutathione (GSH)) concentrations and increased malondialdehyde (MDA) concentrations in the heart. Furthermore, As or/and Cu could induce autophagy in the heart of chickens through decreased mRNA levels of TORC1, TORC2, microtubule associated light chains 3-I (LC3-I) and increased PI3K, AKT1, Beclin1, autophagy associated gene 4B (Atg4B), microtubule associated light chains 3-II (LC3-II), autophagy associated gene 5 (Atg5) and Dynein. Meanwhile, ultrastructural examinations showed that As/Cu could result in the appearance of autolygosomes, autophagic vacuoles and double-membrane structures in the heart. In conclusion, As or/and Cu induced cardiac damage and autophagy via elevating cardiac enzymes activities, inducing oxidative stress and activating the PI3K/AKT/mTORC pathway in heart of chickens. Moreover, As and Cu had a possible synergistic relationship in the heart of chickens.

The Contribution of Superoxide Radical to Cadmium Toxicity in E. coli

Numerous reports suggest the involvement of oxidative stress in cadmium toxicity, but the nature of the reactive species and the mechanism of Cd-induced oxidative damage are not clear. In this study, E. coli mutants were used to investigate mechanisms of Cd toxicity. Effects of Cd on metabolic activity, production of superoxide radical by the respiratory chain, and induction of enzymes controlled by the soxRS regulon were investigated. In E. coli, the soxRS regulon controls defense against O₂·^-and univalent oxidants. Suppression of metabolic activity, inability of E. coli to adapt to new environment, and slow cell division were among the manifestations of Cd toxicity. Cd increased production of O₂·^- by the electron transport chain and prevented the induction of soxRS-controlled protective enzymes, even when the regulon was induced by the redox-cycling agent, paraquat. The effect was not limited to soxRS-dependent proteins and can be attributed to previously reported suppression of protein synthesis by Cd. Increased production of superoxide, combined with inability to express protective enzymes and to replace damaged proteins by de novo protein synthesis, seems to be the main reason for growth stasis and cell death in Cd poisoning.

Alterations in antioxidant function and cell apoptosis in duck spleen exposed to molybdenum and/or cadmium

To investigate the effects of molybdenum (Mo) and/or cadmium (Cd) on antioxidant function and the apoptosis-related genes in duck spleens. Sixty healthy 11-day-old ducks were randomly divided into six groups of 10 ducks (control, low Mo group, high Mo, Cd, low Mo + Cd, and high Mo + Cd groups). All were fed a basal diet containing low or high dietary doses of Mo and/or Cd. Relative spleen weight, antioxidant indices, apoptosis-related gene mRNA expression levels, and ultrastructural changes were evaluated after 120 days. The results showed that the relative spleen weight decreased significantly in the high Mo + Cd treatment group which compared with control group. Malondialdehyde levels increased and xanthine oxidase and catalase activities decreased in the Mo and/or Cd groups compared with levels in the control group. Bak-1 and Caspase-3 expressions were upregulated in the high Mo + Cd group, while Bcl-2 was downregulated. In addition, mitochondrial crest fracture, swelling, vacuolation, deformed nuclei, and karyopyknosis in both Mo + Cd treated groups were more severe than in the other groups. The results suggest that Mo and/or Cd can induce oxidative stress and apoptosis of spleen via effects on the mitochondrial intrinsic pathway. Moreover, the results indicate the two elements have a possible synergistic relationship.

Metal dyshomeostasis based biomarkers of lung cancer using human biofluids

Metals, ratios, interactions and species in serum, urine and bronchoalveolar lavage fluid as biomarkers of lung cancer.

Ameliorative Effect of Arctium lappa Against Cadmium Genotoxicity and Histopathology in Kidney of Wistar Rat

BACKGROUND AND OBJECTIVE

Cadmium (Cd) is a non-essential metal whose dispersion in the environment has increased recently, Cd may enhance cell oxidative stress that leads to DNA damage and apoptotic cell death. The study aimed to evaluate the antioxidative capability of Burdock root 'Arctium lappa' on cadmium-induced oxidative stress and histopathology of the kidney of Wistar rats.

METHODOLOGY

Cadmium was applied in a form of cadmium chloride to three groups (15 mg Cd kg-1) for five weeks with two groups pre-treated with 'Arctium lappa' administration, 100 and 200 mg kg-1 b.wt. Data were analyzed using one way analysis of variance (ANOVA) followed by Least Significant Difference (LSD) test to determine the difference among means using the JMP version 12.

RESULTS

Results revealed that cadmium induced a significant disorganization (p<0.05) of renal structure with collapsed tubular lamina and 76 μm tail length of the cells was observed, while histological sections of kidney pre-treated with 100 mg Arctium lappa kg-1 b.wt., showed a slightly less hypercellularity of glomerulus and reduction in the cell tail (59 μm). Furthermore, histological sections of kidney of rats pre-treated with 200 mg Arctium lappa kg-1 b.wt., showed high improvement of renal tubules and glomerulus with a prominent urinary space beside tail length of cells was recorded as 39 μm which was lower in comparison to other groups.

CONCLUSION

Moreover, cadmium induced cellular destruction of the kidney was resumed with the pre-treatment of the secondary metabolites as an antioxidant compounds that produced from plant extracts. Arctium lappa leaf extract was efficient at both applied doses while 200 mg Arctium lappa kg-1 b.wt., had the most ameliorative effect.

Effects of molybdenum and cadmium on the oxidative damage and kidney apoptosis in Duck

Molybdenum (Mo) is an essential element for human beings and animals; however, high dietary intake of Mo can lead to adverse reactions. Cadmium (Cd) is one of the major transitional metals which has toxic effects in animals. To investigate the co-induced toxic effects of Mo and Cd on oxidative damage and kidney apoptosis in duck, 120 ducks were randomly divided into control group and 5 treatment groups which were treated with a commercial diet containing different dosages of Mo and Cd. Kidney samples were collected on the 60th and 120th days to determine the mRNA expression levels of ceruloplasmin (CP), metallothionein (MT), Bak-1, and Caspase-3 by quantitative RT-PCR. Additionally, we also determined the antioxidant activity indexes and contents of Mo, Cd, copper (Cu), iron (Fe), zinc (Zn), and selenium (Se) in serum. Meanwhile, ultrastructural changes of the kidney were observed. The results showed that glutathione reductase (GR) activity and CP level in serum were decreased in combination groups. In addition, the antioxidant indexes were decreased in co-treated groups compared with single treated groups. The mRNA expression levels of Bak-1 and Caspase-3 increased in co-treated groups. The mRNA expression level of CP in high-dose combination group was downregulated, while the mRNA expression of MT was upregulated except for low-dose Mo group. Additionally, in the later period the content of Cu in serum decreased in joint groups while the contents of Mo and Cd increased. In addition, ultrastructural changes showed mitochondrial crest fracture, swelling, deformed nuclei, and karyopyknosis in co-treated groups. Taken together, it was suggested that dietary Mo and Cd might lead to oxidative stress, kidney apoptosis and disturb homeostasis of trace elements in duck, and it showed a possible synergistic relationship between the two elements.

Castasterone and citric acid treatment restores photosynthetic attributes in Brassica juncea L. under Cd(II) toxicity

Cadmium(II) toxicity is a serious environmental issue warranting effective measures for its mitigation. In the present study, ameliorative effects of a bioactive brassinosteroid, castasterone (CS) and low molecular weight organic acid, citric acid (CA) against the Cd(II) toxicity to Brassica juncea L. were evaluated. Seeds of B. juncea treated with CS (0, 0.01, 1 and 100nM) were sown in cadmium spiked soils (0 and 0.6mmolkg^-1 soil). CA (0.6mmolkg^-1soil) was added to soil one week after sowing seeds. Plants were harvested 30 days after sowing. Phytotoxicity induced by Cd(II) was evident from stunted growth of the plants, malondialdehyde accumulation, reduction in chlorophyll and carotenoid contents, and leaf gas exchange parameters. Cd(II) toxicity was effectively alleviated by seed soaking with CS (100nM) and/ or soil amendment with CA (0.6mMkg^-1 soil). Relative gene expression of genes encoding for some of the key enzymes of pigment metabolism were also analysed. Expression of chlorophyllase (CHLASE) was reduced, while that of phytoene synthase (PSY), and chalcone synthase (CHS) genes were enhanced with CS and/or CA treatments with respect to plants treated with Cd(II) only. Cd also affected the activities of antioxidative enzymes. Plants responded to Cd(II) by accumulation of total sugars. CS (100nM) and CA treatments further enhanced the activities of these parameters and induced the contents of secondary plant pigments (flavonoids and anthocyanins) and proline. The results imply that seed treatment with CS and soil application with CA can effectively alleviate Cd(II) induced toxicity in B. juncea by strengthening its antioxidative defence system and enhancing compatible solute accumulation.

Respiration disruption and detoxification at the protein expression levels in the Pacific oyster (Crassostrea gigas) under zinc exposure

The Pacific oyster (Crassostrea gigas) can accumulate high levels of zinc (Zn) without obvious toxicity, but the related molecular mechanisms are largely unknown. In the present study, C. gigas were exposed to excess Zn for 9days and the differentially expressed proteins (DEPs) were examined using the isobaric tags for relative and absolute quantitation (iTRAQ) method. In total, 2667 proteins containing at least two peptides and detected in both replicates were used for proteomic analysis. Among these DEPs, 332 were up-regulated and 282 were down-regulated. KEGG enrichment analysis of DEPs revealed that Zn exposure mainly distrubed 'tricarboxylic acid (TCA) cycle', 'electron transport chain (ETC)' and 'glutathione (GSH) metabolism' processes in oysters. Further key protein expressions enriched in these metabolism pathways were analyzed. In TCA cycle, Zn inhibited the Fe-containing protein expressions, which may lead to the accumulation of succinate and induce anaerobiosis. In ETC metabolism process, Zn inhibited ETC complex protein expressions, including complex I-IV, which may affect the electron transport process. Furthermore, Zn induced phytochelatin (PC) and glutathione peroxidase (GPX) expression in GSH catabolism. The proteins play important roles in Zn detoxification and ROS elimination process. The transcriptional expressions of genes encoding these proteins were observed using real-time PCR analysis, and there was good consistency between these two datasets. Overall, we provide direct evidence for Zn toxicity and detoxification mechanisms at protein level.