Acute cadmium administration to rats exerts both immunosuppressive and proinflammatory effects in spleen

Cadmium causes spleen toxicity in chickens by regulating mitochondrial unfolded protein response and nuclear receptors response

Cadmium (Cd) is a heavy metal that pollutes the environment and threatens human and animal health via the food chain. The spleen is one of the target organs affected by Cd toxicity. However, the mechanism of Cd toxicity is not fully understood. In this study, 80 chicks were allocated into 4 groups (n = 20) and exposed to different doses of CdCl2 (0 mg/kg, 35 mg/kg, 70 mg/kg and 140 mg/kg) for 90 d. The pathological changes in the spleen, mitochondrial dynamics-related factors, cytochrome P450 (CYP450) enzyme system contents, activities, transcription levels, nuclear receptors (NRs) response molecule levels, and mitochondrial unfolded protein-related factors were detected. The findings indicate that exposure to Cd significantly leads to spleen injury. In Cd groups, the total contents of CYP450 and cytochrome b5 (Cyt b5) increased, and the activities of the CYP450 enzyme system (APND, ERND, AH, and NCR) changed. The NRs response was induced, and the gene levels of AHR/CAR and corresponding CYP450 isoforms (CYP1B1, CYP1A5, CYP1A1, CYP2C18, CYP2D6 and CYP3A4) were found altered. The study found that Cd exposure altered the mRNA expression levels of mitochondrial dynamics-related factors, such as OPA1, Fis1, MFF, Mfn1, and Mfn2, breaking mitochondrial fusion and cleavage and ultimately leading to mitochondrial dysfunction. Changes were detected in the gene levels of several mitochondrial unfolded protein response (mtUPR)-related factors, namely (SIRT1, PGC-1α, NRF1, TFAM, SOD2, and HtrA2). Cd also altered the gene levels of mitochondrial function-related factors (VDAC1, Cyt-C, COA6, PRDX3, RAF and SIRT3). It is showed that Cd can initiate the NRs response, influence the homeostasis of the CPY450 enzyme system, trigger the mtUPR, impair mitochondrial function, and ultimately lead to Cd toxicity in the spleen of chickens.

Cadmium promoted LPS-induced inflammation through TLR4/IκBα/NFκ-B signaling by increasing ROS-mediated incomplete autophagy

Cadmium (Cd) exposure is considered as non-infectious stressor to human and animal health. Recent studies suggest that the immunotoxicity of low dose Cd is not directly apparent, but disrupts the immune responses when infected with some bacteria or virus. But how Cd alters the adaptive immunity organ and cells remains unclear. In this study, we applied lipopolysaccharide (LPS, infectious stressor) to induced inflammation in spleen tissues and T cells, and investigated the effects after Cd exposure and the underlying mechanism. Cd exposure promoted LPS-induced the expressions of the inflammatory factors, induced abnormal initiation of autophagy, but blocked autophagic flux. The effects Cd exposure under LPS activation were reversed by the autophagy promoter Rapamycin. Under LPS activation conditions, Cd also induced oxidative stress by increasing the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and reducing total antioxidant capacity (T-AOC) activity. The increased superoxide dismutase (SOD) activity after Cd exposure might be a negative feedback or passive adaptive regulation of oxidative stress. Cd-increased autophagic flux inhibition and TNF-α expression were reversed by ROS scavenger α-tocopherol (TCP). Furthermore, under LPS activation condition, Cd promoted activation of toll-like receptor 4 (TLR4)/IκBα/NFκ-B signaling pathway and increased TLR4 protein stability, which were abolished by the pretreatment of Rapamycin. The present study confirmed that, by increasing ROS-mediated inhibiting autophagic degradation of TLR4, Cd promoted LPS-induced inflammation in spleen T cells. This study identified the mechanism of autophagy in Cd-aggravated immunotoxicity under infectious stress, which could arouse public attention to synergistic toxicity of Cd and bacterial or virus infection.

Zinc Ameliorates Cadmium-Induced Immunotoxicity by Modulating Splenic Immunosuppressive Indoleamine 2,3-Dioxygenase Activity, Hematological Indices, and CD4+ T Cells via Inhibition of Cadmium Uptake in Male Wistar Rats

Cadmium (Cd)-induced immunotoxicity has become a matter of public health concern owing to its prevalence in the environment consequently, great potential for human exposure. Zinc (Zn) has been known to possess antioxidant, anti-inflammatory, and immune-boosting properties. However, the ameliorating influence of Zn against Cd-induced immunotoxicity connecting the IDO pathway is lacking. Adult male Wistar rats were exposed to normal drinking water with no metal contaminants (group 1), group 2 received drinking water containing 200 μg/L of Cd, group 3 received drinking water containing 200 μg/L of Zn, and group 4 received Cd and Zn as above in drinking water for 42 days. Cd exposure alone significantly triggered the splenic oxidative-inflammatory stress, increased activities of immunosuppressive tryptophan 2,3-dioxygenase (TDO), indoleamine 2,3-dioxygenases (IDO) activities/protein expression, and decreased CD4+ T cell count, and a corresponding increase in the serum kynurenine concentration, as well as alterations in the hematological parameters and histologic structure when compared with the control (p < 0.05). Zn alone did not have any effect relative to the control group while co-exposure significantly (p < 0.05) assuaged the Cd-induced alterations in the studied parameters relative to the control. Cd-induced modifications in IDO 1 protein expression, IDO/TDO activities, oxidative-inflammatory stress, hematological parameters/CD4+ T cell, and histological structure in the spleen of rats within the time course of the investigation were prevented by Zn co-exposure via inhibition of Cd uptake.

Exploration of the immuno-adjuvant effect and mechanism of Anemoside B4 through network pharmacology and experiment verification

BACKGROUND

Extensive investigation has been undertaken about the utilization of saponin adjuvants in vaccines intended for veterinary and human applications. AB4 is the main constituent of the traditional Chinese medicine, Pulsatilla chinensis (Bunge) Regel, and has immunomodulatory activity. However, there is a paucity of reports on AB4 as a potential adjuvant.

PURPOSE

The objective of this work was to clarify the adjuvant role of AB4 and the molecular mechanisms that underlie its immunomodulatory actions.

STUDY DESIGN AND METHODS

The immunomodulatory effects of AB4 were investigated using network pharmacological analyses. These effects were validated by evaluating the developmental status of the immune organs and by using the following techniques: ELISA for the quantification of serum-specific antibodies to determine immune-related cytokine levels; the MTS method for the assessment of proliferative activity of splenic lymphocytes; flow cytometry to analyze lymphocyte and dendritic cell activation status; and western blotting for mechanistic analysis at the protein level.

RESULTS

The network pharmacological analysis predicted a total of 52 targets and 12 pathways for AB4 to exert immunomodulatory effects. In a mouse model with immunity to OVA, the introduction of AB4 resulted in the enhancement of immunological organ growth and maturation, elevation of blood antibodies targeting OVA, and amplification of the production of cytokines associated with Th1 and Th2 immune responses. Additionally, the administration of AB4 resulted in a notable augmentation of lymphocyte proliferation and an elevation in the CD4+/CD8+ T lymphocyte ratios. Furthermore, the administration of AB4 enhanced the maturation process of DCs in the draining LNs and increased the production of co-stimulatory factors and MHC II molecules. AB4 induces the upregulation of TLR4 and IKK proteins, as well as the phosphorylation of NF-κB p65 protein within the TLR4/NF-κB signaling cascade, while concurrently suppressing the expression of IκBα protein.

CONCLUSION

The specific immunoadjuvant effects of AB4 have been demonstrated to modulate the growth and maturation of immune organs and enhance the secretion and cellular activity of pertinent immune molecules. The utilization of network pharmacology, combined within and in vivo vitro assays, clarified the adjuvant function of AB4, which potentially involves the regulation of the TLR4/NF-κB signaling pathway.

Cadmium exposure exacerbates immunological abnormalities in a BTBR T+ Itpr3tf/J autistic mouse model by upregulating inflammatory mediators in CD45R-expressing cells

Autism spectrum disorder (ASD) is a neurodevelopmental illness characterized by behavior, learning, communication, and social interaction abnormalities in various situations. Individuals with impairments usually exhibit restricted and repetitive actions. The actual cause of ASD is yet unknown. It is believed, however, that a mix of genetic and environmental factors may play a role in its development. Certain metals have been linked to the development of neurological diseases, and the prevalence of ASD has shown a positive association with industrialization. Cadmium chloride (Cd) is a neurotoxic chemical linked to cognitive impairment, tremors, and neurodegenerative diseases. The BTBR T+ Itpr3tf/J (BTBR) inbred mice are generally used as a model for ASD and display a range of autistic phenotypes. We looked at how Cd exposure affected the signaling of inflammatory mediators in CD45R-expressing cells in the BTBR mouse model of ASD. In this study, we looked at how Cd affected the expression of numerous markers in the spleen, including IFN-γ, IL-6, NF-κB p65, GM-CSF, iNOS, MCP-1, and Notch1. Furthermore, we investigated the effect of Cd exposure on the expression levels of numerous mRNA molecules in brain tissue, including IFN-γ, IL-6, NF-κB p65, GM-CSF, iNOS, MCP-1, and Notch1. The RT-PCR technique was used for this analysis. Cd exposure increased the number of CD45R+IFN-γ+, CD45R+IL-6+, CD45R+NF-κB p65+, CD45R+GM-CSF+, CD45R+GM-CSF+, CD45R+iNOS+, and CD45R+Notch1+ cells in the spleen of BTBR mice. Cd treatment also enhanced mRNA expression in brain tissue for IFN-γ, IL-6, NF-κB, GM-CSF, iNOS, MCP-1, and Notch1. In general, Cd increases the signaling of inflammatory mediators in BTBR mice. This study is the first to show that Cd exposure causes immune function dysregulation in the BTBR ASD mouse model. As a result, our study supports the role of Cd exposure in the development of ASD.

Pomegranate peel extract, N-Acetylcysteine and their combination with Ornipural alleviate Cadmium-induced toxicity in rats

Cadmium is a major environmental pollutant and a highly toxic metal. It was aimed to determine the effects of pomegranate peel extract (PPE), N-acetylcysteine (NAC) alone and along with Ornipural on cadmium-induced toxicity. Forty-six Wistar Albino male rats were divided into 6 groups and the groups were formed into healthy control, Cadmium group (5 mg/kg/day, oral), Cadmium + Pomegranate peel extract (500 mg/kg, oral), Cadmium + N-acetylcysteine (100 mg/kg, oral), Cadmium + Pomegranate peel extract (500 mg/kg, oral) + Ornipural (1 mL/kg, subcutaneous) and Cadmium + N-acetylcysteine (100 mg/kg, oral) + Ornipural (1 mL/kg, subcutaneous). Cadmium accumulated heavily in both liver and kidney tissue. The administration of N-acetylcysteine and pomegranate peel extract alone reduced cadmium levels in both tissues. N-acetylcysteine treatment prevented the increase in ALT and MDA levels by cadmium damage. N-acetylcysteine + Ornipural treatment inhibited the increase in liver 8-OHdG level in the liver. N-acetylcysteine and N-acetylcysteine + Ornipural treatments prevented the reduced serum MMP2 level. N-acetylcysteine and Pomegranate peel extract + Ornipural treatments significantly reduced the increased liver iNOS level in the liver. In conclusion, NAC therapy may be a successful treatment option for cadmium toxicity. However, further research is needed on the effects of PPE and Ornipural combinations for the treatment of cadmium toxicity. In future studies, various doses of these treatment options (with chelators) should be investigated for cadmium toxicity.

Cadmium induced immunosuppression through TLR-IκBα-NFκB signaling by promoting autophagic degradation

Environmental and occupational exposure to cadmium (Cd) poses a serious threat to human health. Recent studies indicate that Cd perturbs the immune system and increases the risk of pathogenicity and mortality of bacterial or virus infection. However, the underlying mechanism of Cd-modulated immune responses remains unclear. In this study, we aim to investigate the role of Cd in the immune function of mouse spleen tissues and its primary T cells with Concanavalin A (ConA, a well-known T cell mitogen) activation condition, and elucidate the molecular mechanism. The results showed that Cd exposure inhibited ConA-induced the expressions of tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) in mouse spleen tissues. Furthermore, the transcriptomic profile by RNA-sequence reveals that: (1) Cd exposure can alter immune system process; (2) Cd may affect the NFκB signaling pathway. Both in vitro and in vivo results showed that Cd exposure reduced ConA-activated toll-like receptor 9 (TLR9)-IκBα-NFκB signaling, and the expressions of TLR9, TNF-α and IFN-γ, which were effectively reversed by autophagy-lysosomal inhibitors. All these results confirmedly demonstrated that, by promoting the autophagy-lysosomal degradation of TLR9, Cd suppressed immune response under ConA activation condition. This study provides insight on the mechanism of Cd immunnotoxicity, which might contribute to the prevention of Cd toxicity in the future.

Cadmium Exposure Is Associated with Behavioral Deficits and Neuroimmune Dysfunction in BTBR T+ Itpr3tf/J Mice

Autism spectrum disorders (ASD) are neurobehavioral disabilities characterized by impaired social interactions, poor communication skills, and restrictive/repetitive behaviors. Cadmium is a common heavy metal implicated in ASD. In this study, we investigated the effects of Cd exposure on BTBR T+ Itpr3tf/J (BTBR) mice, an ASD model. We looked for changes in repetitive behaviors and sociability through experiments. We also explored the molecular mechanisms underlying the effects of Cd exposure, focusing on proinflammatory cytokines and pathways. Flow cytometry measured IL-17A-, IL-17F-, IL-21-, TNF-α-, STAT3-, and RORγt-expressing CD4+ T cells from the spleens of experimental mice. We then used RT-PCR to analyze IL-17A, IL-17F, IL-21, TNF-α, STAT3, and RORγ mRNA expression in the brain. The results of behavioral experiments showed that Cd exposure significantly increased self-grooming and marble-burying in BTBR mice while decreasing social interactions. Cd exposure also significantly increased the number of CD4+IL-17A+, CD4+IL-17F+, CD4+IL-21+, CD4+TNF-α+, CD4+STAT3+, and CD4+RORγt+ cells, while upregulating the mRNA expression of the six molecules in the brain. Overall, our results suggest that oral exposure to Cd aggravates behavioral and immune abnormalities in an ASD animal model. These findings have important implications for ASD etiology and provide further evidence of heavy metals contributing to neurodevelopmental disorders through proinflammatory effects.

Effect of occupational co-exposure to lead and cadmium on selected immunomodulatory cytokines

Occupational exposure to heavy metals like lead (Pb) and cadmium (Cd) is associated with the development of several diseases. The objective of this study was to determine the effect of occupational co-exposure to Pb and Cd on the blood levels of selected immune-modulatory cytokines related to T helper (Th), that is, Th1, interleukin-2 (IL-2), Th2, (IL-4 and IL-10), and Th17, (IL-17) cells. The study comprised 207 individuals divided into two groups: exposed (n = 110) and nonexposed (n = 97). Blood Pb and Cd were determined using Graphite Furnace Atomic Absorption Spectroscopy, and serum levels of cytokines were measured using enzyme-linked immunosorbent assay (ELISA). The study revealed significantly higher blood Pb and Cd levels in the exposed group. A significant decrease in Th1 cytokine-IL-2 and Th2 cytokine-IL-10 was found, while IL-4 (Th2 cytokine) and IL-17 (Th17) levels were higher in the exposed group. In the mixed exposure analysis, among all the selected cytokines, IL-4 levels were significantly different between individuals having higher levels of both Pb and Cd versus lower levels of Pb and Cd. While IL-2 levels were highest among the low Pb and Cd group, the IL-17 levels were highest among individuals with higher Cd levels. The study demonstrated that co-exposure to low levels of Pb and Cd might have an immune-modulatory effect. The data suggested a metal-induced pro-inflammatory immune response.

MiR-182-5p/TLR4/NF-κB axis contributes to the protective effect of caffeic acid phenethyl ester against cadmium-induced spleen toxicity and associated damage in mice

Cadmium (Cd) is a toxic heavy metal pollutant that can be accumulated in organs including the spleen, thereby threatening human health. In this study, the effect of caffeic acid phenethyl ester (CAPE, a bioactive component of honeybee propolis) on CdCl2-induced spleen toxicity and underlying mechanisms were examined in mice. Histological examinations revealed that CAPE (10 μmol/kg/day b.w.) could mitigate spleen damage induced by CdCl2 (1.5 mg/kg/day b.w.) in mice. Compared to the mice treated only by CdCl2, CAPE administration increased the body weight while decreasing the spleen weight, spleen Cd content and spleen to body ratio of the CdCl2-treated mice. Western blot and ELISA tests revealed that CAPE suppressed CdCl2-induced inflammation (indicated by the decreases in the levels of inflammatory indictors). TUNEL and Western blot results showed that CAPE suppressed CdCl2-induced apoptosis through reducing the percentage of TUNEL-positive cells and regulating apoptosis factors. The antagonistic effect of CAPE against CdCl2-induced spleen toxicity was realized by increasing miR-182-5p expression to regulate the TLR4/NF-κB pathway. Therefore, CAPE could be a food-derived spleen protector to counteract Cd-induced spleen toxicity through alleviating apoptosis and inflammation via the miR-182-5p/TLR4/NF-κB axis.

Disentangling the roles of social and individual effects on cadmium tolerance in the ant Temnothorax nylanderi

Urbanization brings new pressures for individuals. Among them, trace elements, such as cadmium, are important stressors. A recent study highlights a weaker negative effect of cadmium on city colonies relative to their forest counterparts in the ant Temnothorax nylanderi. Here, we aim to test whether the better tolerance of city colonies in this species results from a better ability of workers to rear larvae despite stressful conditions and/or a better ability of larvae to develop properly despite stressful conditions. We performed a cross-fostering experiment of workers and larvae from city and forest colonies, in common garden conditions in the laboratory. Colonies were fed using cadmium-enriched or cadmium-free food for 2 months, and we measured four life-history traits. As expected, cadmium had a negative impact on all traits. Unexpectedly, we did not observe a better tolerance of city colonies to cadmium, contrary to our previous study, which prevented us from disentangling the respective contributions of workers and larvae to cadmium tolerance. Interestingly, forest colonies seemed to be of better quality in our laboratory conditions. Finally, colony size increased adult survival, but only in the absence of cadmium, suggesting that social buffering could collapse with strong external disturbances.

Effects of Cadmium Exposure on the Immune System and Immunoregulation

Cadmium (Cd), a biologically non-essential heavy metal, is widespread in the environment, including the air, water, and soil, and is widely present in foods and quantum dot preparations. Cd enters the body primarily through inhalation and ingestion. Its biological half-life in humans is 10-35 years; therefore, Cd poses long-term health risks. While most studies on Cd toxicity have focused on organ and tissue damage, the immunotoxicity of Cd has drawn increasing attention recently. Cd accumulates in immune cells, modulates the function of the immune system, triggers immunological responses, and leads to diverse health problems. Cd acts as an immunotoxic agent by regulating the activity and apoptosis of immune cells, altering the secretion of immune cytokines, inducing reactive oxygen species (ROS) production and oxidative stress, changing the frequency of T lymphocyte subsets, and altering the production of selective antibodies in immune cells. This review summarizes the immunological toxicity of Cd, elucidates the mechanisms underlying Cd toxicity in terms of innate immunity and adaptive immunity, and discusses potential strategies to alleviate the adverse effects of Cd on the immune system.

Immunotoxicology of cadmium: Cells of the immune system as targets and effectors of cadmium toxicity

Cadmium (Cd) has been listed as one of the most toxic substances affecting numerous tissues/organs, including the immune system. Due to variations in studies examining Cd effects on the immune system (exposure regime, experimental systems, immune endpoint measured), data on Cd immunotoxicity in humans and experimental animals are inconsistent. However, it is clear that Cd can affect cells of the immune system and can modulate some immune responses. Due to the complex nature of the immune system and its activities which are determined by multiple interactions, the underlying mechanisms involved in the immunotoxicity of this metal are still vague. Here, the current knowledge regarding the interaction of Cd with cells of the immune system, which may affect immune responses as well as potential mechanisms of consequent biological effects of such activities, is reviewed. Tissue injury caused by Cd-induced effects on innate cell activities depicts components of the immune system as mediators/effectors of Cd tissue toxicity. Cd-induced immune alterations, which may compromise host defense against pathogenic microorganisms and homeostatic reparative activities, stress this metal as an important health hazard.

Cadmium induces apoptosis of pig lymph nodes by regulating the PI3K/AKT/HIF-1α pathway

OBJECTIVE

This study was aimed to explore the possible mechanism of environmental metal cadmium (Cd) inducing apoptosis of pig lymph nodes.

METHOD

10 healthy 6-week-old weaned piglets were randomly divided into two groups (n = 5 pigs/group). The control group was fed with a basic diet, and the test group was fed with a basic diet of 20 mg/kg CdCl₂.

RESULTS

The Cd deposition in mesenteric lymph nodes (MLN), inguinal lymph nodes (ILN) and submaxillary lymph nodes (SLN) after Cd exposure was 2.37 folds, 1.4 folds and 1.8 folds of the control group, respectively. And the rate of MLN and ILN apoptotic cells in the Cd group was 4.11 folds and 9.18 folds of the control group, respectively. The mRNA levels of SOD1, SOD2, CAT, GPX1 and GSH in the Cd group were reduced. Similarly, the two-phase detoxification enzymes had a significant downward trend. Cd exposure decreased the activities of GSH, GSH-Px, SOD, CAT, and increased H₂O₂ and MDA levels. The mRNA and protein levels of Drp1 and Mff in the Cd group were higher than the corresponding control group, and the mRNA and protein levels of Mfn1 and Mfn2 were lower than those in the control group. In addition, the mRNA and protein levels of pro-apoptotic genes in the Cd group were lower than those in the control group. Cd can significantly reduce the expression of PI3K, AKT and HIF-1α in the three lymph nodes. In summary, Cd induces oxidative stress and regulates the PI3K/AKT/HIF-1α signal transduction pathway to cause mitochondrial dynamics disorder, which leads to the apoptosis of pig lymph nodes, suggesting that Cd-induced mitochondrial pathway apoptosis is related to Cd pig lymph nodes play an important role in the toxicity mechanism.

Cadmium and immunologically-mediated homeostasis of anatomical barrier tissues

Cadmium (Cd) is a toxic heavy metal that when absorbed into the body causes nephrotoxicity and effects in other tissues.Anatomical barrier tissues are tissues that prevent the entry of pathogens and include skin, mucus membranes and the immune system. The adverse effects of Cd-induced immune cell's activity are the most extensively studied in the kidneys and the liver. There are though fewer data relating the effect of this metal on the other tissues, particularly in those in which cells of the immune system form local circuits of tissue defense, maintaining immune-mediated homeostasis. In this work, data on the direct and indirect effects of Cd on anatomical barrier tissue of inner and outer body surfaces (the lungs, gut, reproductive organs, and skin) were summarized.

Proinflammatory effects of environmental cadmium boost resistance to opportunistic pathogen Aspergillus fumigatus: Implications for sustained low-level pulmonary inflammation?

Cadmium (Cd) is one of the most toxic environmental heavy metals to which the general population is exposed mainly via the oral route. Owing to its immunomodulatory potential, orally acquired Cd affects antimicrobial immune defense in several organs, including the lungs. While there are data concerning Cd and viral and bacterial pulmonary infections, effects on fungal infections are not studied yet. In the present study, the effect of the Cd (5 mg/L for 30 days, in drinking water, the average daily Cd intake 0.641 ± 0.089 mg/kg) on the immune response of rats to pulmonary A. fumigatus infection was examined. Data obtained showed that orally acquired cadmium does not affect the elimination of the fungus in immunocompetent rats owing to the preservation of some aspects of innate immune responses (lung leukocyte infiltration and NBT reduction) and an increase in other (increased numbers of mucus-producing goblet cells, MPO release). Cd does not affect an IFN-γ response in lung leukocytes during the infection (despite suppression of cytokine production in cells of lung-draining lymph nodes), while it stimulates IL-17 and suppresses IL-10 response to the fungus. As a result, the elimination of the fungus occurs in a milieu with the prevailing proinflammatory response in Cd-exposed animals that preserved fungal elimination from the lungs, though with more intense injury to the lung tissue. Therefore, the proinflammatory microenvironment in the lungs created by Cd that sustains inflammatory/immune response to the fungus to which humans are exposed for a lifetime, raises a concern of orally acquired Cd as a risk factor for the development of chronic low-grade pulmonary inflammation.

The effects of cadmium exposure in the induction of inflammation

Inflammation is a physiological process essential for maintaining homeostatic mechanisms in human, but however, exaggerated inflammatory responses are closely related to many chronic diseases. Cadmium (Cd) is a heavy metal with high toxicity when present in food, water and air has the potential of eliciting inflammatory reactions, with a major health risk to human. This review aimed to elucidate on the major routes of Cd exposure, the main organs affected by the exposure, the degree of toxicity as well as the roles of the toxic effects on the immune system which results to inflammatory responses. Immune modulation by Cd may cause serious adverse health effects in humans. Various studies have highlighted the ability of Cd as an environmental pollutant involved in the modulation of the innate, adaptive and mucosal immune responses in relations to the release of chemokine, gene expression, and susceptibility to microbial infections.

Comparative assessment of the effects of meso-2,3-dimercaptosuccinic acid and salinomycin on spleen function of cadmium-exposed mice

In this study, we present experimental data on the effects of meso-2,3-dimercaptosuccinic acid (DMSA) and tetraethylammonium salt of salinomycinic acid (Sal) on cadmium-induced spleen dysfunction and altered essential metal balance in mice. Sixty-day-old male mice (ICR line) were randomly divided into four groups: untreated control group (Ctrl)-obtained distilled water for 28 days, toxic control group (Cd)-exposed to cadmium acetate dihydrate at average daily dose of 20mg/kg body weight (BW) for 14 days, Cd + DMSA group-obtained cadmium acetate dihydrate as the toxic control group followed by treatment with 20mg/kg BW DMSA for 2 weeks, and Cd + Sal group-mice exposed to cadmium acetate dihydrate at average daily dose of 20mg/kg BW for 2 weeks followed by administration of Sal at an average daily dose of 20mg/kg BW for 2 weeks. The compounds were administered orally via the drinking water of the animals. We found that cadmium exposure caused splenomegaly and reduced the hemoglobin and hematocrit levels and total red blood cell count compared with untreated controls. Cadmium intoxication of mice induced accumulation of the toxic metal ion in the blood and spleen. Alterations in the endogenous levels of calcium (Ca) and iron (Fe) in the spleen of cadmium-exposed mice compared with those in untreated controls were observed. Treatment of cadmium-exposed mice with DMSA or Sal recovered the spleen weight and hematological parameters to normal control values, decreased cadmium concentration in the blood and spleen, and improved splenic architecture. The results prove that Sal is a potential antidote for treatment of Cd-induced spleen dysfunction.

Puerarin prevents cadmium-induced hepatic cell damage by suppressing apoptosis and restoring autophagic flux

Cadmium (Cd) is a common heavy metal contamination that is highly toxic to liver. Puerarin (PU), a potent free radical scavenger, has been shown to exert cytoprotective effect in numerous pathological processes. However, whether PU affords protection against Cd-induced hepatotoxicity remains unclear to be known. Here, we aimed to investigate the protective effect of PU on Cd-induced hepatotoxicity in an immortalized mouse hepatocyte line, AML-12. First, Cd-induced cytotoxicity in AML-12 cells was obviously ameliorated by PU treatment. Also, Cd-induced apoptotic cell death was markedly alleviated by PU treatment, evidenced by two methods. Simultaneously, Cd-elevated malondialdehyde and reactive oxygen species levels were significantly reduced by PU administration, demonstrating the antioxidant effect of PU against Cd exposure. Moreover, Cd-induced blockage of autophagic flux in AML-12 cells was obviously restored by PU treatment, evidenced by immunoblot analysis of autophagy marker proteins and tandem fluorescent-tagged LC3 method. Resultantly, Cd-induced autophagosome accumulation was significantly alleviated by PU treatment. In conclusion, these observations demonstrate that PU treatment alleviates Cd-induced hepatic cell damage by inhibiting apoptosis and restoring autophagy activity, which is intimately related with its antioxidant activity.

Inhibition of Autophagy Alleviates Cadmium-Induced Mouse Spleen and Human B Cells Apoptosis

Cadmium (Cd) is a toxic heavy metal that can accumulate and cause severe damage to many organs, such as liver, kidney, lung, etc. Cd also significantly suppresses immunity, however, the underlying mechanism involved in Cd-induced immunnotoxicity is still unclear. The present study indicated that semichronic Cd exposure (7 days) induced apoptotic damage of mouse spleen. In human Ramos B cells, Cd exposure also induced apoptosis, which was dependent on Cd-induced vacuole membrane protein 1 (VMP1) expression and autophagy. Cd-induced autophagy and apoptosis were abated when VMP1 expression was knockdown. In addition, Cd-induced VMP1 expression, autophagy, and apoptosis were dependent on the elevation of Ca2+ and reactive oxygen species (ROS). More important, Cd exposure also induced VMP1 expression and autophagy in mouse spleen tissue, and the intraperitoneal injection of the autophagy inhibitor chloroquine (CQ) into mice effectively reduced Cd-induced spleen apoptotic damage. Taken together, these results indicate Cd-induced autophagy, promotes apoptosis in immune cells, and inhibition of autophagy can alleviate Cd-induced spleen and immune cell apoptosis. This study might provide the groundwork for future studies on Cd-induced immunomodulatory effects and immune diseases.

Chronic low-level cadmium exposure in rats affects cytokine production by activated T cells

Cadmium is a toxic metal and common environmental contaminant. Chronic cadmium exposure results in kidney, bone, reproductive, and immune toxicity as well as cancer. Cadmium induces splenomegaly and affects the adaptive immune system, but specific effects vary depending on the dose, model, and endpoint. This study investigates the effects of subchronic, oral, and low-dose cadmium exposure (32 ppm cadmium chloride in drinking water for 10 weeks) on the rat immune system, focusing on T cell function. Cadmium-exposed animals demonstrated slight increases in the spleen-to-body weight ratios, and decreases in overall splenic cell numbers and markers of oxidative stress. The relative ratios of splenic cell populations remained similar, except for modest increases in regulatory T cells in the cadmium-exposed animals. Cadmium exposure also significantly increased the production of IFNγ, a pro-inflammatory cytokine, and IL-10, a cytokine produced by multiple T cell subsets that typically inhibits IFNγ expression, by activated T cells. The increase in IFNγ and IL-10 suggests that cadmium exposure may affect multiple T cell subsets. Collectively, this study suggests that subchronic, low-dose cadmium exposure impacts both immune cell function and cellularity, and may enhance inflammatory responses.

Induction of pathological changes and impaired expression of cytokines in developing female rat spleen after chronic excess fluoride exposure

This study was designed to investigate the effects of excessive fluoride on spleen toxicity. Twenty-four healthy female rats were randomly divided into two groups, each of 12 rats. Each group of female rats was given a control diet and either F− = 0 mg/L or an excessive F− = 150 mg/L in the drinking water for 120 days. The histomorphological and ultrastructural changes in their splenic tissues were observed under light and transmission electron microscopes. DNA damage and splenocyte apoptosis were examined using the micronucleus (MN) assay, single-cell gel electrophoresis (SCGE), and flow cytometry. The expression levels of cytokines, including interleukin (IL)-1β, IL-2, IL-6, and tumor necrosis factor (TNF)-α, were determined through immunohistochemistry and Western-blot analysis. Results demonstrated that the histomorphological characteristics and ultrastructure of the splenic tissues were affected by excessive fluoride. Nuclear dying, nuclear membrane dissolution, mitochondrial vacuolation, and endoplasmic reticulum dilation were observed. SCGE and MN assays showed that the nuclear DNA of splenocytes was damaged by fluoride treatment, and splenocyte apoptosis was exacerbated in the fluoride group. With damage to the splenocyte structure and DNA, the protein expression levels of IL-1β, IL-2, IL-6, and TNF-α were significantly downregulated by exposure to fluoride. Excessive fluoride ingestion caused splenic pathological damage and abnormal cytokine expression in female rats.

Protective effects of Fragaria ananassa methanolic extract in a rat model of cadmium chloride-induced neurotoxicity

Cadmium (Cd) is a common environmental toxicant that has harmful effects on plants, animals, and humans. The present study evaluated the protective effects of Fragaria ananassa methanolic extract (SME) on cadmium chloride (CdCl₂)-induced neuronal toxicity in rats. Male albino rats were intraperitoneally (i.p) injected with CdCl₂ (6.5 mg/kg) for 5 days with or without the SME (250 mg/kg). We measured the levels of Cd, lipid peroxidation (LPO), nitric oxide, glutathione (GSH), and oxidative enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase, and glutathione reductase (GR) in the whole brain homogenate. Compared with the control group, the Cd-intoxicated group showed a marked increase in the brain levels of Cd, LPO, and nitric oxide and a decrease in the levels of GSH and all tested antioxidant enzymes. Compared with Cd-intoxicated rats, the rats pretreated with SME showed restoration of oxidative balance in the brain tissue. While the expression of brain SOD2, CAT, glutathione peroxidase 1, and GR was down-regulated in the Cd-treated group, the expression of these enzymes was up-regulated in rats pretreated with SME. In addition, administration of SME before CdCl₂ increased the Bcl-2 expression, but significantly decreased the expression of Bax. Immunohistochemical analysis showed that compared with Cd-intoxicated rats, rats pretreated with SME showed a decrease in the protein expression of tumor necrosis factor α (TNF-α). Our findings indicate that SME protects the brain tissue from Cd-induced neuronal toxicity by improving the antioxidant system and increasing antiapoptotic and anti-inflammatory activities.

Chronic cadmium exposure induced hepatic cellular stress and inflammation in aged female mice

Previous studies have revealed that acute cadmium (Cd) exposure led to inflammation in different organs through an oxidative stress mechanism. However, whether chronic Cd exposure induces inflammation in liver and the mechanistic link between inflammation and cell stress remains unclear. In the present study, we investigated the effects of chronic Cd exposure on hepatic cellular stress and inflammatory responses. Female CD1 mice were administrated with CdCl₂ (10 and 100 mg/L) in drinking water for 57 weeks. Our results showed that the mRNA levels of Inos and the protein content of HO-1, markers of oxidative stress, were markedly increased in Cd-treated mice. In addition, the protein level of GRP78, the chaperone of endoplasmic reticulum (ER) stress, was significantly increased in Cd-treated mice. The expression of the proteins CHOP and peIF2α, two proteins downstream of ER stress, was also upregulated in the Cd-100 mg/L and Cd-10 mg/L group, respectively. Moreover, there were increased inflammatory cells existing in liver after Cd administration. Besides, there was a significant elevation in the mRNA level of Mip-2, Il-10 and Il-12 in the Cd-100 mg/L group. The mRNA level of Tgf-β was also upregulated in Cd-treated mice. Moreover, we also found that the number of Ki67-positive hepatic cells was increased in the Cd-10 mg/L group. Hence, our results indicated that chronic Cd exposure induced oxidative stress, ER stress, inflammatory responses and proliferation in the liver of aged female mice.

The protective role of selenium against cadmium-induced hepatotoxicity in laying hens: Expression of Hsps and inflammation-related genes and modulation of elements homeostasis

The purpose of this study was to examine the potential role of high selenium (Se) diets in alleviating chronic cadmium (Cd) hepatic toxicity in laying hens. In the present study, 128 healthy 31-week-old laying hens were fed a diet supplemented with Se (Na₂SeO₃, 2 mg/kg), Cd (CdCl₂, 150 mg/kg), or both Se and Cd (150 mg/kg of CdCl₂ and 2 mg/kg of Na₂SeO₃) for 90 days. The expression levels of heat shock proteins (Hsps, including Hsp60, Hsp70 and Hsp90) and inflammation-related factors, including nuclear factor-kappa B p50 (NF-κB), cyclooxygenase-2 (COX-2), prostaglandin E synthases (PTGES), interleukin 1-beta (IL-1β), and tumor necrosis factor-α (TNF-α) were investigated. The concentrations of 28 elements were also determined. The results indicated that Cd treatment significantly increased the mRNA and protein expression levels of Hsps and significantly improved the expression of inflammation-related genes. Moreover, Cd addition to the diets resulted in disturbances in the systemic balance of 13 elements, leading to decrease in the concentrations of Cr, Mn, Sr, Ba, and Hg and increase in Li, B, Ca, Ti, Fe, Cu, Mo, and Cd concentrations. Treatment with Se significantly alleviated Cd-induced hepatic toxicity, as evidenced by a reduction in Hsp60, Hsp70, Hsp90, NF-κB, COX-2, PTGES, TNF-α, and IL-1β expression. Additionally, Se and Cd co-treatment alleviated the changes in Li, B, Ca, Fe, Ti, Cu, Mo, Cd, Cr, Se, Sr, Ba, and Hg concentrations, which was in contrast to that upon Cd induction. The study indicated that Se could help against the negative effects of Cd and may be related to the alleviation of Cd-induced Hsps stress and the inflammatory responses along with modulating the element homeostasis.

Cadmium induces BNIP3-dependent autophagy in chicken spleen by modulating miR-33-AMPK axis

Cadmium (Cd), a widespread environmental pollutant, has toxic effects on organs including spleen. However, the underlying mechanisms of Cd induced spleen toxicity and the roles of micro-RNA (miRNA) in this process remain poorly understood. To investigate this, cadmium chloride (CdCl₂, 10 mg/kg) was administered in the diet of chickens for 90 days. Electron microscopy, qPCR and Western blot were performed. Results showed that Cd exposure suppressed miR-33-5q which increased the levels of AMPK. Subsequently, significant decrease in AKT/mTOR signaling and HSP70 were observed. Concurrently, levels of NF-κB, p-JNK/JNK increased significantly. Moreover, the expression of BNIP3 and other autophagy markers (LC3-I, LC3-II, Beclin-1) increased significantly. Additionally, the levels of ions (Ca, Cr, Se, Sr, Sn, Ba) and (Na, Mg, V, Fe, Mo, Cu, Zn, Cd) significantly decreased and increased, respectively. Taken together, we conclude that Cd induced the deregulation of miR-33-AMPK axis led to BNIP3-dependent autophagy in chicken spleen through AKT/mTOR and HSP70-NF-κB/JNK signal pathways. In-addition Cd could affect ion homeostasis in chicken spleen.

Impact of oral cadmium intoxication on levels of different essential trace elements and oxidative stress measures in mice: a response to dose

The study evaluated the effect of oral intoxication of cadmium and the possible causes of oxidative stress and its preferential accumulation in different organs as well as sub-sequential effects in mice. Twenty-four Swiss albino male mice were divided into three groups viz., normal control group without cadmium chloride (CdCl₂), whereas a daily dose of 0.5 and 1.2 mg of CdCl₂ was orally administered for a period of a week to dose group 1 (DG-1) and dose group 2 (DG-2), respectively. A significant increase in the severity of cadmium toxicity was observed in animals as evidenced by aggravation in liver enzymes viz., serum alanine aminotransferase and aspartate transaminase, whereas lower levels of antioxidative stress markers in liver and kidney tissues of treated mice were observed as compared to normal control group. A significant depletion of calcium levels in liver tissues of DG-1 (217.36 ± 1.73 μg/g of wet tissues) and DG-2 (186.41 ± 1.56 μg/g of wet tissues) groups, along with Cd accumulation, was observed. To summarize, the current study would increase our understanding with respect to dose-dependent absorption of Cd and its toxicity led to mortality as well as adverse health effects in the body of mice. Graphical abstract ᅟ.

Cadmium and chlorpyrifos inhibit cellular immune response in spleen of rats

Cadmium (Cd) and chlorpyrifos (CPF) are common pollutants coexisting in the environment, and both of them have been reported to have immunotoxicity to organisms. However, the joint effects of these two chemicals on the immune system are still unknown. In this study, we used CdCl₂ and CPF to study their combined effects on immune functions in the spleen of rats. In in vivo experiments, SD rats were exposed to different doses of CdCl₂ (0.7 and 6 mg kg^-1 body weight/day) and CPF (1.7 and 15 mg kg^-1 body weight/day) or their combinations for consecutive 28 days. The proliferation and cytokine production ability of the splenocytes isolated from the treated animals were assessed. In in vitro experiments, we used different concentrations of CdCl₂ and CPF to treat concanavalin A (Con A)-induced splenocytes isolated from untreated rats. We found that the combination of CPF and high dose of CdCl₂ had a synergistic inhibitory effect on production of IFN-γ by spleen cells induced by Con A. The in vitro results showed that two chemicals had different effects on the cell proliferation and cytokine production depending on the exposure doses and time. This result suggests that exposure to both CdCl₂ and CPF at the environmentally-relevant low dose may be potentially more hazardous than exposure to each individual toxicant.

Studies on the protective effect of the artichoke (Cynara scolymus) leaf extract against cadmium toxicity-induced oxidative stress, hepatorenal damage, and immunosuppressive and hematological disorders in rats

Our objective was to explore the protective effect of artichoke leaf extract (ALE) against cadmium (Cd) toxicity-induced oxidative organ damage in rats. Male albino Wistar rats were divided into four equal groups of eight animals each. The first group was assigned as a control. Groups 2-4 were orally administered with ALE (300 mg/kg bw), Cd (CdCl₂, 100 mg/L drinking water), and ALE plus Cd, respectively, daily for 4 weeks. After treatment with Cd, the liver and kidney malondialdehyde (MDA) increased significantly compared with the control rats. The sera interleukin (IL)-1β, tumor necrosis factor (TNF-α), and IL-10, liver transaminase, urea, creatinine, and peripheral neutrophil count were significantly increased in Cd-exposed rats compared to the control group. The reduced glutathione (GSH), glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT) decreased in the liver and kidney in Cd-exposed group. In combination treatment, Cd and ALE significantly improved immune response, an antioxidant system, and hepatorenal function with a significant decline in MDA. In conclusion, ALE ameliorates the immunosuppressive and hepatorenal oxidative injury stimulated by Cd in rats. These results suggest that artichoke has shown promising effects against adverse effects of Cd toxicity.

Alleviation of lead-induced oxidative stress and immune damage by selenium in chicken bursa of Fabricius

We investigated lead (Pb)-induced oxidative stress and immune damage in the chicken bursa of Fabricius (BF) and the ameliorative effect of selenium (Se). Seven-day-old male chickens were randomly divided into four groups and were provided standard diet and drinking water, Na₂SeO₃ added to the standard diet and drinking water, standard diet and (CH₃COO)₂Pb added to drinking water, and Na₂SeO₃ added to the standard diet and (CH₃COO)₂Pb added to drinking water for 30, 60, and 90 days. The presence of Pb inhibited total antioxidant capacity (T-AOC), glutathione peroxidase (GPx), glutathione S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT) activities; decreased glutathione (GSH) content; increased malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) contents; inhibited interleukin (IL)-2 and interferon-γ (IFN-γ) messenger RNA (mRNA) expression; and increased IL-4, IL-6, IL-10, IL-12β, and IL-17 mRNA expression. The presence of Se relieved all of the above Pb-induced changes. There were close correlations among GSH, CAT, T-AOC, SOD, GPx, MDA, and H₂O₂ and among IL-2, IL-4, IL-6, IL-12β, IL-17, and IFN-γ. Our data showed that Pb caused oxidative stress and immune damage in the chicken BF. Se alleviated Pb-induced oxidative stress and immune damage in the chicken BF.

Cadmium-induced immune abnormality is a key pathogenic event in human and rat models of preeclampsia

With increased industrial development, cadmium is an increasingly important environmental pollutant. Studies have identified various adverse effects of cadmium on human beings. However, the relationships between cadmium pollution and the pathogenesis of preeclampsia remain elusive. The objective of this study is to explore the effects of cadmium on immune system among preeclamptic patients and rats. The results showed that the cadmium levels in the peripheral blood of preeclamptic patients were significantly higher than those observed in normal pregnancy. Based on it, a novel rat model of preeclampsia was established by the intraperitoneal administration of cadmium chloride (CdCl2) (0.125 mg of Cd/kg body weight) on gestational days 9-14. Key features of preeclampsia, including hypertension, proteinuria, placental abnormalities and small foetal size, appeared in pregnant rats after the administration of low-dose of CdCl2. Cadmium increased immunoglobulin production, mainly angiotensin II type 1-receptor-agonistic autoantibodies (AT1-AA), by increasing the expression of activation-induced cytosine deaminase (AID) in B cells. AID is critical for the maturation of antibody and autoantibody responses. In addition, angiotensin II type 1-receptor-agonistic autoantibody, which emerged recently as a potential pathogenic contributor to PE, was responsible for the deposition of complement component 5 (C5) in kidneys of pregnant rats via angiotensin II type 1 receptor (AT1R) activation. C5a is a fragment of C5 that is released during C5 activation. Selectively interfering with C5a signalling by a complement C5a receptor-specific antagonist significantly attenuated hypertension and proteinuria in Cd-injected pregnant rats. Our results suggest that cadmium induces immune abnormalities that may be a key pathogenic contributor to preeclampsia and provide new insights into treatment strategies of preeclampsia.

Cadmium modulates hematopoietic stem and progenitor cells and skews toward myelopoiesis in mice

The heavy metal cadmium (Cd) is known to modulate immunity and cause osteoporosis. However, how Cd influences on hematopoiesis remain largely unknown. Herein, we show that wild-type C57BL/6 (B6) mice exposed to Cd for 3months had expanded bone marrow (BM) populations of long-term hematopoietic stem cells (LT-HSCs), common myeloid progenitors (CMPs) and granulocyte-macrophage progenitors (GMPs), while having reduced populations of multipotent progenitors (MPPs) and common lymphoid progenitors (CLPs). A competitive mixed BM transplantation assay indicates that BM from Cd-treated mice had impaired LT-HSC ability to differentiate into mature cells. In accordance with increased myeloid progenitors and decreased lymphoid progenitors, the BM and spleens of Cd-treated mice had more monocytes and/or neutrophils and fewer B cells and T cells. Cd impaired the ability of the non-hematopoietic system to support LT-HSCs, in that lethally irradiated Cd-treated recipients transplanted with normal BM cells had reduced LT-HSCs after the hematopoietic system was fully reconstituted. This is consistent with reduced osteoblasts, a known critical component for HSC niche, observed in Cd-treated mice. Conversely, lethally irradiated control recipients transplanted with BM cells from Cd-treated mice had normal LT-HSC reconstitution. Furthermore, both control mice and Cd-treated mice that received Alendronate, a clinical drug used for treating osteoporosis, had BM increases of LT-HSCs. Thus, the results suggest Cd increase of LT-HSCs is due to effects on HSCs and not on osteoblasts, although, Cd causes osteoblast reduction and impaired niche function for maintaining HSCs. Furthermore, Cd skews HSCs toward myelopoiesis.

Interactions between cadmium and decabrominated diphenyl ether on blood cells count in rats-Multiple factorial regression analysis

The objective of this study was to assess toxicity of Cd and BDE-209 mixture on haematological parameters in subacutely exposed rats and to determine the presence and type of interactions between these two chemicals using multiple factorial regression analysis. Furthermore, for the assessment of interaction type, an isobologram based methodology was applied and compared with multiple factorial regression analysis. Chemicals were given by oral gavage to the male Wistar rats weighing 200-240g for 28days. Animals were divided in 16 groups (8/group): control vehiculum group, three groups of rats were treated with 2.5, 7.5 or 15mg Cd/kg/day. These doses were chosen on the bases of literature data and reflect relatively high Cd environmental exposure, three groups of rats were treated with 1000, 2000 or 4000mg BDE-209/kg/bw/day, doses proved to induce toxic effects in rats. Furthermore, nine groups of animals were treated with different mixtures of Cd and BDE-209 containing doses of Cd and BDE-209 stated above. Blood samples were taken at the end of experiment and red blood cells, white blood cells and platelets counts were determined. For interaction assessment multiple factorial regression analysis and fitted isobologram approach were used. In this study, we focused on multiple factorial regression analysis as a method for interaction assessment. We also investigated the interactions between Cd and BDE-209 by the derived model for the description of the obtained fitted isobologram curves. Current study indicated that co-exposure to Cd and BDE-209 can result in significant decrease in RBC count, increase in WBC count and decrease in PLT count, when compared with controls. Multiple factorial regression analysis used for the assessment of interactions type between Cd and BDE-209 indicated synergism for the effect on RBC count and no interactions i.e. additivity for the effects on WBC and PLT counts. On the other hand, isobologram based approach showed slight antagonism for the effects on RBC and WBC while no interactions were proved for the joint effect on PLT count. These results confirm that the assessment of interactions between chemicals in the mixture greatly depends on the concept or method used for this evaluation.

Sublethal health effects in laboratory rodents from environmentally relevant exposures to oil sands contaminants

Increasing activity of oil sands extraction and processing in northern Alberta is marked by ongoing controversy about the nature and extent of associated environmental impacts. Bitumen contains a mixture of toxic chemicals, including metals and residual polycyclic aromatic hydrocarbons (PAHs), whose release into the environment poses a distinct risk to the surrounding environment, plus wildlife and human health. In the present study, the authors evaluated several subclinical biomarkers of exposure and effect to mixtures of metals (Pb, Cd, and Hg) and/or PAHs (3 alkylated forms) at environmentally relevant concentrations (100-fold and 10-fold higher than the maximum dissolved concentrations found in snow, to simulate a worst-case scenario), using laboratory mice as a model for future studies of small mammals in the wild. Both metals and alkyl-PAHs exposure were associated with 1) increased relative liver, kidney, and spleen size; 2) alterations in the homeostasis of the antioxidant vitamins A and E in liver; and 3) compromised glutathione redox status in testes, with results also indicating synergistic interactions from co-exposure. The combination of morphometric and oxidative stress biomarkers provide reliable and sensitive measures of the response to contaminant exposure in a mammalian model, suggesting associated physiological costs. Based on the present experimental study, the authors propose that wild small mammals will prove to be valuable sentinel species reflecting sublethal health effects from oil sands-related contaminants. The present study's results also present a basis for the interpretation of future field data.

Can the Hyperaccumulating Plant Arabidopsis halleri in Feed Influence a Given Consumer Organism (Rattus norvegicus var. alba)?

Zinc and cadmium concentrations in rat (Rattus norvegicus var. alba) tissues were analyzed by inductively coupled plasma optical emission spectrometry. Rats were fed the zinc and cadmium hyperaccumulating plant, Arabidopsis halleri. When compared to the control group, a Cd increase in all tissues (liver, kidneys, small intestine, spleen, testes, muscle), with the exception of bone tissue was observed. In comparison to the control group, the kidneys, liver and small intestine contained 375, 162, and 80 times more Cd, respectively. Differences between zinc concentrations in rats fed with A. halleri and those of the control group were significant only in the small intestine and kidney tissues. Results suggest using the hyperaccumulating plant A. halleri as a feed stresses the consumer organism not through its Zn content, but through its Cd content.

Insight into the oxidative stress induced by lead and/or cadmium in blood, liver and kidneys

Besides being important occupational hazards, lead and cadmium are nowadays metals of great environmental concern. Both metals, without any physiological functions, can induce serious adverse health effects in various organs and tissues. Although Pb and Cd are non-redox metals, one of the important mechanisms underlying their toxicity is oxidative stress induction as a result of the generation of reactive species and/or depletion of the antioxidant defense system. Considering that the co-exposure to both metals is a much more realistic scenario, the effects of these metals on oxidative status when simultaneously present in the organism have become one of the contemporary issues in toxicology. This paper reviews short and long term studies conducted on Pb or Cd-induced oxidative stress in blood, liver and kidneys as the most prominent target organs of the toxicity of these metals and proposes the possible molecular mechanisms of the observed effects. The review is also focused on the results obtained for the effects of the combined treatment with Pb and Cd on oxidative status in target organs and on the mechanisms of their possible interactions.

Hepatic oxidative stress and inflammatory responses with cadmium exposure in male mice

Cadmium (Cd), a non-essential heavy metal, is one of the major environmental contaminants with grave toxicological consequences globally. In the present study, the effects of Cd on hepatic oxidative stress and inflammatory responses in mice were evaluated. Male adult mice were orally exposed to 3, 10 and 30mg/L CdCl2 supplied in the drinking water for 7 and 21 days. Histopathological changes and the alterations of the main parameters related to oxidative stress and inflammatory responses in the liver were observed. Hepatic malondialdehyde (MDA) contents increased significantly after treatment with 30mg/L CdCl2 for 21 days, and the contents of glutathione (GSH) increased significantly in both 10 and 30mg/L CdCl2 treated groups. The hepatic activities of glutathione peroxidase (GPX), catalase (CAT) and glutathione S-transferase (GST) increased significantly after the treatment with 30mg/L CdCl2 for 21 days. In accordance with the enzyme activities, the transcription status of hepatic superoxide dismutase 1 (Sod1), superoxide dismutase 2 (Sod2), Cat, Gpx, Gstα1, glutathione synthetase (Gss), glutathione reductase (Gr) and heme oxygenase 1 (Ho1) were also increased by high dose (30mg/L) or long period (21 days) exposure. In addition, the serum levels of tumor necrosis factor α (TNFα), interleukin 6 (IL6) and interleukin 1β (IL1β) increased significantly in the groups treated with 30mg/L CdCl2 for 21 days. And the genes of TNFα, IL6, interleukin 1α (IL1α), inducible nitric oxide synthase (iNOS) and interferon γ (IFNγ) were also increased in the liver of mice when exposed to relative high dose of CdCl2 for 7 or 21 days. Taken together, the results of this study suggested that the exposure to Cd had the potential to induce immunotoxicity accompanied with oxidative stress in the liver of mice.