Cadmium transporters in the kidney and cadmium-induced nephrotoxicity

Farnesol attenuates cadmium-induced kidney injury by mitigating oxidative stress, inflammation and necroptosis and upregulating cytoglobin and PPARγ in rats

Heavy metals are environmental pollutants that can harm animals and humans even at low concentrations. Cadmium (Cd) is known for its serious health effects on different organs and its toxicity is associated with oxidative stress (OS) and inflammation. Farnesol (FAR), a sesquiterpene alcohol found in many vegetables and fruits, possesses promising anti-inflammatory and antioxidant activities. This study evaluated the effect of FAR on Cd-induced kidney injury, pinpointing its effect of the redox status, inflammation, fibrosis and necroptosis. Rats in this study received FAR for 14 days and Cd on day 7. Elevated serum creatinine, urea and uric acid, and several kidney histopathological alterations were observed in Cd-administered rats. Cd increased MDA, decreased antioxidants, downregulated PPARγ and upregulated NF-κB p65, IL-6, TNF-α, and IL-1β. Necroptosis mediators (RIP1, RIP3, MLKL, and caspase-8) and α-SMA were upregulated, and collagen deposition was increased in Cd-administered rats. FAR ameliorated kidney injury markers and tissue damage, attenuated OS, suppressed NF-κB and inflammatory mediators, and enhanced antioxidants. In addition, FAR suppressed RIP1, RIP3, MLKL, caspase-8, and α-SMA, and enhanced kidney cytoglobin and PPARγ. In conclusion, FAR protects against Cd nephrotoxicity by suppressing OS, inflammatory response and necroptosis, effects associated with enhanced antioxidants, cytoglobin, and PPARγ.

Cardiotoxicity of Cadmium and Its Effects on Heart Efficiency During Early and Late Chick Embryogenesis

Cadmium (Cd) is a dangerous heavy metal that is non-degradable in the environment. Many organs can accumulate Cd and adversely affect organ function and health. Cd is considered as a teratogenic and embryotoxic agent. This study aims to evaluate the teratogenicity of Cd at concentrations lesser than the permissible and its effects on the heart during chick embryogenesis. Fertilized eggs of the chick Gallus domesticus were divided into; control, saline injected and four experimental groups injected with single doses of 5, 25, 50 or 75 µM of CdCl2. Histological observations of the heart before hatching and the cardiomyocytes after hatching were recorded. Morphometric measurements of heart chambers were achieved at 3, 4 and 6 days of incubation. Electrocardiograph and respiratory rate were recorded at tenth day. Different cardiac problems had been brought on by Cd. In comparison to controls, the heart looked much larger, and in certain cases, growth retardation was seen. Degeneration in heart walls and malformations of dorsal aorta were noticed. Morphometrically, the width and wall thickness of heart chambers showed significant changes. Heart beats and respiratory rate significantly decreased compared to control. The cardiotoxic effect of Cd on heart compartments structure and function was dose dependent. One of Cd toxicity is its ability to induce cellular oxidative stress. The heart in particular is sensitive to oxidative stress. Cardiac oxidative stress might intensify heart failure and promote disease progression. Calcium is one of the components that is needed for normal heart work. Cd might interfere with calcium metabolism by removing it from the body.

Antioxidative and anti-cytogenotoxic potential of Lysiphyllum strychnifolium (Craib) A. Schmitz extracts against cadmium-induced toxicity in human embryonic kidney (HEK293) and dermal fibroblast (HDF) cells

Exposure to cadmium (Cd) results in bioaccumulation and irreversible damage; this encourages an investigation of alternatives to address Cd toxicity, using natural compounds. Lysiphyllum strychnifolium, a well-known Thai medicinal plant, was investigated for its phytochemical compounds and corresponding bioactivities, including antioxidant and anti-cytogenotoxic effects against Cd toxicity in HEK293 renal and HDF dermal cell models. The crude extract of L. strychnifolium (LsCrude) was partitioned into four fractions, using sequential polarity solvents (hexane, dichloromethane, ethyl acetate, and water, denoted as LsH, LsD, LsE, and LsW, respectively). The extraction yields were 1.79 %, 5.08 %, 8.53 %, and 70.25 % (w/w), respectively. Phytochemical screening revealed the presence of tannins, alkaloids, and flavonoids in LsCrude and its fractions, except for LsH. LsE exhibited the highest concentrations of phenolics (286.83 ± 6.83 mg GAE/g extract) and flavonoids (86.36 ± 1.29 mg QE/g extract). Subsequent 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging and ferric-reducing ability of plasma (FRAP) reducing powder assays demonstrated the high antioxidant capacity of LsCrude and its fractions. The lowest IC50 value (9.11 ± 0.43 μg/mL) in the DPPH assay corresponded to LsW, whereas the highest total FRAP value (6.06 ± 0.70 mg QE Eq./g dry mass) corresponded to LsE. MTT and alkaline comet assays revealed the lack of toxicity of the extracts, which were considered safe. Upon exposure to Cd at the CC50 level, HEK293 cells treated with LsE suppressed Cd-induced damage. HDF cells treated with LsCrude, LsD, or LsE attenuated Cd-induced damage. In the pre-treatment, LsD protected the HDF cells against Cd-mediated cytogenotoxicity. These anti-cytogenotoxic potentials are likely due to the antioxidant properties of the phytochemicals. Our findings highlight the cyto-geno-protective properties of L. strychnifolium stem extracts against Cd toxicity in HEK293 and HDF cells, and provide a novel approach for combating oxidative stress and DNA damage caused by environmental pollutants.

Uric acid mediates the relationship between mixed heavy metal exposure and renal function in older adult people

Background

Population aging is a pivotal trend observed globally, and the exposure to heavy metals can exacerbate the aging process and lead to kidney damage. However, the impact of combined heavy metal exposure on renal function among older individuals remains elusive. Our study employs machine learning techniques to delve into the effects and underlying mechanisms of mixed exposure to heavy metals on the renal function of the aging population.

Methods

This study extracted comprehensive data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2015 and 2020. A total of 3,175 participants aged 60 years and above, with complete information on six metals - lead, cadmium, manganese, cobalt, mercury, and selenium, along with relevant covariates, were included in the study. To assess the impact of single or mixed metal exposure on the renal function of older adult individuals, various statistical techniques were employed: multiple logistic regression, weighted quantitative sum (WQS) regression, Bayesian kernel machine regression (BKMR), and mediation effects analysis.

Results

Multiple logistic regression revealed that selenium and manganese were protective factors for chronic kidney disease (CKD). Cobalt was a risk factor for CKD. High concentrations of lead, cadmium, and cobalt were risk factors for urinary albumin creatinine ratio (ACR). WQS analyses revealed that mixed metal exposure was positively correlated with estimated glomerular filtration rate (eGFR) but negatively correlated with CKD. Selenium and manganese can neutralize the effects of other metals on eGFR. Mixed metal exposure was positively correlated with ACR, with lead and cadmium having a substantial effect. Mediation analysis showed that uric acid (UA) had a mediating effect of 9.7% and -19.7% in the association between mixed metals exposure and proteinuria and CKD, respectively.

Conclusion

The impact of heavy metals on renal function in the older adult differs from that of adolescents and adults. This study suggests that elevated levels of mixed metals exposure are linked to proteinuria and CKD, with UA serving as a mediating factor.

Perindopril Dampens Cd-induced Nephrotoxicity by Suppressing Inflammatory Burden, Ang II/Ang 1-7, and Apoptosis Signaling Pathways

Cadmium (Cd) is one of the most abundant toxic heavy metals, and its exposure is linked to serious kidney intoxication, a major health problem. Evidence reported that inflammatory damage is a key factor in Cd renal intoxication. Perindopril (PER) is an angiotensin-converting enzyme inhibitor approved for treating hypertension and other cardiovascular problems. Significantly, RAS activation results in inflammatory damage. Our study aimed to examine the renoprotective effects of PER in Cd-induced nephrotoxicity, the impact of inflammation, and the underlying molecular mechanisms. PER was given at a dose of 1 mg/kg per day. Cd was injected at a dose of 1.2 mg/kg, as a single dose. Treatment with PER led to a significant decrease in serum levels of urea, creatinine, uric acid, and urine albumin/creatinine ratio. PER effectively mitigated inflammation by decreasing MPO, NO, IL-1β, IL-6, and INF-γ levels mediated by downregulating NF-κB expression and suppressing JAK-1 and STAT3 phosphorylation. PER modulates Ang II/Ang 1-7 axis in Cd-intoxicated rats by decreasing Ang II expression and increasing Ang-(1-7) expression. PER inhibits Cd-induced apoptosis by lowering Bax, cytochrome c, and cleaved caspase 3 expressions while increasing Bcl-2 expression. In conclusion, PER dampens Cd-induced kidney intoxication by modulating Ang II/Ang 1-7 axis, suppressing NF-κB, JAK-1/STAT3, and apoptosis signals.

Overexpression of Lias Gene Alleviates Cadmium-Induced Kidney Injury in Mice Involving Multiple Effects: Metabolism, Oxidative Stress, and Inflammation

Oxidative stress is an important mechanism underlying toxicity induced by cadmium (Cd) exposure. However, there are significant differences of the antioxidant baseline in different populations. This means that different human has different intensity of oxidative stress in vivo after exposure to toxicants. LiasH/H mouse is a specific model which is created by genetically modifying the Lias 3'-untranslated region (3'-UTR). LiasH/H mice express high levels of LA and have high endogenous antioxidant capacity which is approximately 150% higher than wild-type C57BL/6 J mice (WT, Lias+/+). But more importantly, they have dual roles of metal chelator and antioxidant. Here, we applied this mouse model to evaluate the effect of endogenous antioxidant levels in the body on alleviating Cd-induced renal injury including Cd metabolism, oxidative stress, and inflammation. In the experiment, mice drank water containing Cd (50 mg/L), for 12 weeks. Many biomarkers of Cd metabolism, oxidative stress, inflammation, and major pathological changes in the kidney were examined. The results showed overexpression of the Lias gene decreased Cd burden in the body of mice, mitigated oxidative stress, attenuated the inflammatory response, and subsequent alleviated cadmium-induced kidney injury in mice.

The Protective Effects of Taurine, a Non-essential Amino Acid, Against Metals Toxicities: A Review Article

Taurine is a non-proteinogenic amino acid derived from cysteine. It is involved in several phenomena such as the regulation of growth and differentiation, osmoregulation, neurohormonal modulation, and lipid metabolism. Taurine is important because of its high levels in several tissues such as the central nervous system (CNS), heart, skeletal muscles, retinal membranes, and platelets. In this report, we present the functional properties of taurine indicating that it has potential effects on various metal toxicities. Therefore, a comprehensive literature review was performed using the Scopus, PubMed, and Web of Science databases. According to the search keywords, 61 articles were included in the study. The results indicate that taurine protects tissues against metal toxicity through enhancement of enzymatic and non-enzymatic antioxidant capacity, modulation of oxidative stress, anti-inflammatory and anti-apoptotic effects, involvement in different molecular pathways, and interference with the activity of various enzymes. Taken together, taurine is a natural supplement that presents antitoxic effects against many types of compounds, especially metals, suggesting public consumption of this amino acid as a prophylactic agent against the incidence of metal toxicity.

Cornus officinalis var. koreana Kitam extracts alleviate cadmium-induced renal fibrosis by targeting matrix metallopeptidase 9

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis var. koreana Kitam (Cornus officinalis) is a commonly used Chinese herbal medicine and has a good clinical efficacy in kidney and liver diseases. Recent years, a number of studies reported the significant effects of Cornus officinalis on renal fibrosis. However, it is still unclear about the underlying specific mechanism, the bioactive ingredients, and the target gene regulatory network.

AIM OF THE STUDY

We investigated the impact of Cornus officinalis extract on cadmium-induced renal fibrosis, screened the bioactive ingredients of Cornus officinalis using a pharmacological sub-network analysis, and explored the regulatory effects of Cornus officinalis extracts on target gene matrix metallopeptidase 9 (MMP9).

METHODS

Male C57BL/6N mice were treated with single or combinatorial agents such as saline, cadmium chloride, Cornus officinalis, Isoginkgetin and FSL-1. Isoginkgetin is a compound with anti-MMP9 activity. FSL-1 can induce MMP9 expression. Masson staining and Western blot and immunohistochemistry analyses were used for assessing renal fibrosis. In addition, wound healing model was established using BUMPT (Boston university mouse proximal tubular) cells to investigate how Cornus officinalis affected cadmium-induced cell migration. The main Cornus officinalis bioactive compounds were identified by UHPLC-MS (Ultra-high-performance liquid chromatography - mass spectrometry). The MMP9 target for Cornus officinalis active ingredients were confirmed through a pharmacological sub-network analysis.

RESULTS

Aqueous extracts of Cornus officinalis protected from renal dysfunction and kidney fibrosis induced by cadmium chloride in mice. In vitro experiments validated that Cornus officinalis extracts inhibited cell migration ability especially in cadmium chloride condition. The sub-network analysis and chemical components profiling technique revealed the active compounds of Cornus officinalis. Cellular thermal shift assay verified the binding abilities of three active components Daidzein, N-Acetyl-L-tyrosine or Swertisin with matrix metalloproteinase-9. Gelatin zymography assay revealed that the activity of MMP9 was inhibited by the three active components. We further confirmed that MMP9 was involved in the process of Cornus officinalis extracts reducing renal fibrosis. Cornus officinalis attenuated the cadmium-induced renal fibrosis was correlated with decreased expression of MMP9, collagen I, α-SMA (alpha-smooth muscle actin) and vimentin.

CONCLUSIONS

This study demonstrated that Cornus officinalis extracts could alleviate the cadmium chloride-induced renal fibrosis by targeting MMP9, and might provide new insights into the mechanism of treating renal fibrosis by Cornus officinalis.

Tetramethylpyrazine Antagonizes the Subchronic Cadmium Exposure-Induced Oxidative Damage in Mouse Livers via the Nrf2/HO-1 Pathway

Hepatic oxidative stress is an important mechanism of Cd-induced hepatotoxicity, and it is ameliorated by TMP. However, this underlying mechanism remains to be elucidated. To investigate the mechanism of the protective effect of TMP on liver injuries in mice induced by subchronic cadmium exposure, 60 healthy male ICR mice were randomly divided into five groups of 12 mice each, namely, control (CON), Cd (2 mg/kg of CdCl2), Cd + 100 mg/kg of TMP, Cd + 150 mg/kg of TMP, and Cd + 200 mg/kg of TMP, and were acclimatized and fed for 7 d. The five groups of mice were gavaged for 28 consecutive days with a maximum dose of 0.2 mL/10 g/day. Except for the control group, all groups were given fluoride (35 mg/kg) by an intraperitoneal injection on the last day of the experiment. The results of this study show that compared with the Cd group, TMP attenuated CdCl2-induced pathological changes in the liver and improved the ultrastructure of liver cells, and TMP significantly decreased the MDA level (p < 0.05) and increased the levels of T-AOC, T-SOD, and GSH (p < 0.05). The results of mRNA detection show that TMP significantly increased the levels of Nrf2 in the liver compared with the Cd group as well as the HO-1 and mRNA expression levels in the liver (p < 0.05). In conclusion, TMP could inhibit oxidative stress and attenuate Cd group-induced liver injuries by activating the Nrf2 pathway.

Co-exposure to Environmentally Relevant Levels of Molybdenum and Cadmium Induces Oxidative Stress and Ferroptosis in the Ovary of Ducks

Excessive doses of molybdenum (Mo) and cadmium (Cd) have toxic effects on animals. Nevertheless, the reproductive toxicity elicited by Mo and Cd co-exposure remains obscure. To evaluate the co-induce toxic impacts of Mo and Cd on ovaries, 8-day-old 40 healthy ducks were stochastically distributed to four groups and were raised a basal diet supplemented with Cd (4 mg/kg Cd) and/or Mo (100 mg/kg Mo). In the 16th week, ovary tissues were gathered. The data revealed that Mo and/or Cd decreased GSH content, CAT, T-SOD, and GSH-Px activities and increased MDA and H2O2 levels. Moreover, there was a significant decrease in nuclear Nrf2 protein level and its related downstream factors, while cytoplasmic Nrf2 protein level showed a substantial increase. Additionally, a marked elevation was observed in ferrous ion content and TFRC, GCLC, SLC7A11, ACSL4, and PTGS2 expression levels, while FTH1, FTL1, FPN1, and GPX4 expression levels were conversely reduced. These indicators exhibited more marked changes in the joint exposure group. In brief, our results announced that Mo and/or Cd resulted in oxidative stress and ferroptosis in duck ovaries. Synchronously, the Cd and Mo mixture intensified the impacts.

Mechanism of cadmium-induced nephrotoxicity

Heavy metals are found naturally in our environment and have many uses and applications in daily life. However, high concentrations of metals may be a result of pollution due to industrialization. In particular, cadmium (Cd), a white metal abundantly distributed in the terrestrial crust, is found in mines together with zinc, which accumulates after volcanic eruption or is found naturally in the sea and earth. High levels of Cd have been associated with disease. In the human body, Cd accumulates in two ways: via inhalation or consumption, mainly of plants or fish contaminated with high concentrations. Several international organizations have been working to establish the limit values of heavy metals in food, water, and the environment to avoid their toxic effects. Increased Cd levels may induce kidney, liver, or neurological diseases. Cd mainly accumulates in the kidney, causing renal disease in people exposed to moderate to high levels, which leads to the development of end-stage chronic kidney disease or death. The aim of this review is to provide an overview of Cd-induced nephrotoxicity, the mechanisms of Cd damage, and the current treatments used to reduce the toxic effects of Cd exposure.

Cadmium Induces Kidney Iron Deficiency and Chronic Kidney Injury by Interfering with the Iron Metabolism in Rats

Cadmium (Cd) is a common environmental pollutant and occupational toxicant that seriously affects various mammalian organs, especially the kidney. Iron ion is an essential trace element in the body, and the disorder of iron metabolism is involved in the development of multiple pathological processes. An iron overload can induce a new type of cell death, defined as ferroptosis. However, whether iron metabolism is abnormal in Cd-induced nephrotoxicity and the role of ferroptosis in Cd-induced nephrotoxicity need to be further elucidated. Sprague Dawley male rats were randomly assigned into three groups: a control group, a 50 mg/L CdCl2-treated group, and a 75 mg/L CdCl2-treated group by drinking water for 1 month and 6 months, respectively. The results showed that Cd could induce renal histopathological abnormalities and dysfunction, disrupt the mitochondria's ultrastructure, and increase the ROS and MDA content. Next, Cd exposure caused GSH/GPX4 axis blockade, increased FTH1 and COX2 expression, decreased ACSL4 expression, and significantly decreased the iron content in proximal tubular cells or kidney tissues. Further study showed that the expression of iron absorption-related genes SLC11A2, CUBN, LRP2, SLC39A14, and SLC39A8 decreased in proximal tubular cells or kidneys after Cd exposure, while TFRC and iron export-related gene SLC40A1 did not change significantly. Moreover, Cd exposure increased SLC11A2 gene expression and decreased SLC40A1 gene expression in the duodenum. Finally, NAC or Fer-1 partially alleviated Cd-induced proximal tubular cell damage, while DFO and Erastin further aggravated Cd-induced cell damage. In conclusion, our results indicated that Cd could cause iron deficiency and chronic kidney injury by interfering with the iron metabolism rather than typical ferroptosis. Our findings suggest that an abnormal iron metabolism may contribute to Cd-induced nephrotoxicity, providing a novel approach to preventing kidney disease in clinical practice.

N-methyl-d-aspartate receptor 1 activation mediates cadmium-induced epithelial-mesenchymal transition in proximal tubular cells

Cadmium (Cd) is a commonly found environmental pollutant and is known to damage multiple organs with kidneys being the most common one. N-methyl-d-aspartate receptor 1 (NMDAR1) is a ligand-gated ion channel that is highly permeable to calcium ion (Ca2+). Because Cd2+ and Ca2+ have structural and physicochemical similarities, whether and how Cd could interfere NMDAR1 function to cause renal epithelial cells dysfunction remains unknown. In this study, we investigated the role of NMDAR1 in Cd-induced renal damage and found that Cd treatment upregulated NMDAR1 expression and promoted epithelial-mesenchymal transition (EMT) in mouse kidneys in vivo and human proximal tubular epithelial HK-2 cells in vitro, which were accompanied with activation of the inositol-requiring enzyme 1 (IRE-1α) / spliced X box binding protein-1 (XBP-1s) pathway, an indicative of endoplasmic reticulum (ER) stress. Mechanistically, NMDAR1 upregulation by Cd promoted Ca2+ channel opening and Ca2+ influx, resulting in ER stress and subsequently EMT in HK-2 cells. Inhibition of NMDAR1 by pharmacological antagonist MK-801 significantly attenuated Cd-induced Ca2+ influx, ER stress, and EMT. Pretreatment with the IRE-1α/XBP-1s pathway inhibitor STF-083010 also restored the epithelial phenotype of Cd-treated HK-2 cells. Therefore, our findings suggest that NMDAR1 activation mediates Cd-induced EMT in proximal epithelial cells likely through the IRE-1α/XBP-1s pathway, supporting the idea that NMDAR1 could be a potential therapeutic target for Cd-induced renal damage.

Environmental pollutants induce NLRP3 inflammasome activation and pyroptosis: Roles and mechanisms in various diseases

Environmental pollution is changing with economic development. Most environmental pollutants are characterized by stable chemical properties, strong migration, potential toxicity, and multiple exposure routes. Harmful substances are discharged excessively, and large quantities of unknown new compounds are emerging, being transmitted and amplifying in the food chain. The increasingly severe problems of environmental pollution have forced people to re-examine the relationship between environmental pollution and health. Pyroptosis and activation of the NLRP3 inflammasome are critical in maintaining the immune balance and regulating the inflammatory process. Numerous diseases caused by environmental pollutants are closely related to NLRP3 inflammasome activation and pyroptosis. We intend to systematically explain the steps and important events that are common in life but easily overlooked by which environmental pollutants activate the NLRP3 inflammasome and pyroptosis pathways. This comprehensive review also discusses the interaction network between environmental pollutants, the NLRP3 inflammasome, pyroptosis, and diseases. Thus, research progress on the impact of decreasing oxidative stress levels to inhibit the NLRP3 inflammasome and pyroptosis, thereby repairing homeostasis and reshaping health, is systematically examined. This review aims to deepen the understanding of the impact of environmental pollutants on life and health and provide a theoretical basis and potential programs for the development of corresponding treatment strategies.

Hsp27 over expression protect against cadmium induced nephrotoxicity in Drosophila melanogaster

Cadmium (Cd) exposure to the animals including humans is reported as nephrotoxic compounds i.e., disturbing redox status (increase oxidative stress), mitochondrial dysfunction, renal cell death and altered transporters in the renal system. Hsp27 (a small heat shock protein) has been shown as one of the modulators in the renal dysfunction and increased against the Cd induced toxicity. However, no studies are reported on the genetic modulation of stress protein against the Cd-induced nephrotoxicity. The current study aimed to examine the protective role of hsp27 overexpression against the Cd-induced nephrotoxicity using Drosophila melanogaster as an animal model. D. melanogaster renal system includes nephrocytes and Malpighian tubules (MTs) that show the functional similarity with mammalian kidney nephron. Overexpression of the hsp27 was found to reduce the Cd induced oxidative stress, rescue cell death in MTs of Cd exposed D. melanogaster larvae. The rescued GSH level, NADPH level and glucose 6 phosphate dehydrogenase (G6PD) activity were also observed in the MTs of the Cd exposed organism. Function (efflux activity and fluid secretion rate) of the MTs was restored in Cd exposed hsp27 overexpressed larvae. Further, results were confirmed by restored brush border microvilli density and reduced uric acid level. Tissue specific knockdown of hsp27 developed Cd like phenotypes in MTs and the phenotypes enhanced in Cd exposed condition. The present study clearly shows the role of hsp27 overexpression in restoration of the MTs function and protection against the Cd induced renal toxicity.

Alleviative effect of melatonin against the nephrotoxicity induced by cadmium exposure through regulating renal oxidative stress, inflammatory reaction, and fibrosis in a mouse model

Chronic cadmium (Cd) exposure causes severe adverse health effects on the human body, especially the kidney tissue. Studies have demonstrated oxidative stress to be involved in renal pathological variations after exposure to Cd, but few effective treatments are available for the disease yet. Therefore, the present study was carried out to investigate the potential therapeutic intervention and its underlying molecular mechanisms of melatonin (MT), a natural antioxidant with multiple biological activities, against renal injury caused by Cd exposure in mice. C57BL/6 male mice (eight-week-old) were intragastrically administered with CdCl2, MT, or both for 30 days. Biochemical analysis showed that MT intervention significantly improved the SOD, GSH, and CAT activities while markedly decreasing the kidney MDA content of the mice exposed to Cd. Histological examination indicated that Cd exposure resulted in the atrophy of the renal glomerular, the degeneration and dilation of tubules, and the accumulation of fibrocytes. By contrast, MT administration effectively ameliorated the histological outcome of the injured kidney tissue. Moreover, administrating MT significantly inhibited proinflammatory cytokines TNF-α and iNOS expression in Cd-treated mice. Further, MT treatment markedly suppressed the expressions of renal fibrosis-related factors TGF-β1, α-SMA, and collagen Ⅰ in the injured renal tissue and the accumulation and development of renal fibrosis. In addition, the administration of MT significantly reduced the expression of caspase-3 and cell apoptotic death in the kidney tissue of Cd-exposed mice. In all, the data showed that MT has a compelling therapeutic potential in alleviating the pathological variations of renal injury caused by Cd exposure.

Nrf2 protects against renal fibrosis induced by chronic cadmium exposure in mice

Environmental cadmium (Cd) exposure is a serious public health concern, as the kidney is the primary target for Cd exposure. The present study aimed to investigate the role and underlying mechanisms of nuclear factor erythroid-derived 2-like 2 (Nrf2) in renal fibrosis induced by chronic Cd exposure. Nrf2 knockout (Nrf2-KO) mice and their wild-type littermates (Nrf2-WT) were exposed to 100 or 200 ppm Cd in drinking water for up to 16 or 24 weeks. Following the Cd exposures, Nrf2-KO mice showed elevated urinary neutrophil gelatinase-associated lipocalin (NGAL) and BUN levels compared to Nrf2-WT mice. Masson's trichrome staining and expression of fibrosis-associated proteins revealed that more severe renal fibrosis occurred in Nrf2-KO than that in Nrf2-WT mice. Renal Cd content in the Nrf2-KO mice exposed to 200 ppm Cd was lower than that in Nrf2-WT mice, which might be a consequence of the severe renal fibrosis in the Nrf2-KO mice. Mechanistic studies showed that Nrf2-KO mice exhibited higher levels of oxidative damage, lower antioxidant levels, and more regulated cell death, apoptosis in particular, than those in Nrf2-WT mice caused by Cd exposure. In conclusion, Nrf2-KO mice were more prone to develop renal fibrosis induced by chronic Cd exposure, partially due to a weakened antioxidant, detoxification capacity and increased oxidative damage.

Single-cell transcriptomic analysis reveals the adverse effects of cadmium on the trajectory of neuronal maturation

Cadmium (Cd) is an extensively existing environmental pollutant that has neurotoxic effects. However, the molecular mechanism of Cd on neuronal maturation is unveiled. Single-cell RNA sequencing (scRNA-seq) has been widely used to uncover cellular heterogeneity and is a powerful tool to reconstruct the developmental trajectory of neurons. In this study, neural stem cells (NSCs) from subventricular zone (SVZ) of newborn mice were treated with CdCl2 for 24 h and differentiated for 7 days to obtain neuronal lineage cells. Then scRNA-seq analysis identified five cell stages with different maturity in neuronal lineage cells. Our findings revealed that Cd altered the trajectory of maturation of neuronal lineage cells by decreasing the number of cells in different stages and hindering their maturation. Cd induced differential transcriptome expression in different cell subpopulations in a stage-specific manner. Specifically, Cd induced oxidative damage and changed the proportion of cell cycle phases in the early stage of neuronal development. Furthermore, the autocrine and paracrine signals of Wnt5a were downregulated in the low mature neurons in response to Cd. Importantly, activation of Wnt5a effectively rescued the number of neurons and promoted their maturation. Taken together, the findings of this study provide new and comprehensive insights into the adverse effect of Cd on neuronal maturation.

Expression of TaNCL2-A ameliorates cadmium toxicity by increasing calcium and enzymatic antioxidants activities in arabidopsis

Cadmium (Cd) is a heavy metal that occurs naturally in the environment and is toxic to both animals and plants. The impact of Cd toxicity is shown to be reduced by the exogenous application of calcium (Ca) in crop plants. The sodium/calcium exchanger-like (NCL) protein is involved in Ca enrichment in the cytoplasm by transporting it from the vacuole in the exchange of cytosolic sodium (Na). However, it has not been utilized to ameliorate the Cd toxicity, to date. An elevated expression of TaNCL2-A gene in the root and shoot tissues of bread wheat seedlings, and a higher growth rate of recombinant yeast cells, suggested its role in Cd stress response. The TaNCL2-A expressing transgenic Arabidopsis lines exhibited significant Cd tolerance with increased Ca (∼10-fold) accumulation. The proline content and antioxidant enzymes activities were increased while oxidative stress-related molecules such as H₂O₂ and MDA were reduced in the transgenic lines. In addition, the growth and yield parameters of transgenic lines such as seed germination rate, root length, leaf biomass, leaf area index, rosette diameter, leaf length and width, and silique count, along with various physiological indicators like chlorophyll, carotenoid, and relative water contents were also improved in comparison to the control plants. Further, the transgenic lines exhibited significant salinity and osmotic stress tolerance, as well. Taken together, these results suggested that the TaNCL2-A could mitigate Cd toxicity along with salinity and osmotic stress. This gene may also be utilized for phytoremediation and Cd sequestration in future studies.

Toxic effects of cadmium exposure on intestinal histology, oxidative stress, microbial community, and transcriptome change in the mud crab (Scylla paramamosain)

Cadmium is one of hazardous pollutants that has a great threat to aquatic organisms and ecosystems. The intestine plays important roles in barrier function and immunity to defend against environmental stress. However, whether cadmium exposure caused the intestine injury is not well studied. Thus, the aim of this study was to explore the potential mechanisms of cadmium toxicity in the intestine of mud crab (Scylla paramamosain) via physiological, histological, microbial community, and transcriptional analyses. Mud crabs were exposed to 0, 0.01, and 0.125 mg/L cadmium. After a 21-day of cadmium exposure, 0.125 mg/L cadmium caused intestine damaged by decreasing superoxide dismutase and catalase activities, and increasing hydrogen peroxide and malondialdehyde levels. Integrated biological index analysis confirmed that the toxicity of cadmium exhibited a concentration-dependent manner. Comparative transcriptional analyses showed that the up-regulations of several genes associated with heat shock proteins, detoxification and anti-oxidant defense, and two key signaling pathways (PI3k-Akt and apoptosis) revealed an adaptive response mechanism against cadmium exposure. Transcriptomic analysis also suggested that cadmium exposure disturbed the expression of ion transport and immune-related genes, indicating that it has negative effects on the immune functions of the mud crab. Furthermore, the intestinal microbial diversity and composition were significantly influenced by cadmium exposure. The abundance of the dominant phyla Fusobacteria and Bacteroidetes significantly changed after cadmium exposure. KEGG pathway analysis demonstrated that cadmium exposure could change energy metabolism and environmental information processing. Overall, we concluded that excessive cadmium exposure could be potentially exerted adverse effects to the mud crab health by inducing oxidative damage, decreasing immune system, disrupting metabolic function, and altering intestinal microbial composition. These results provided a novel insight into the mechanism of cadmium toxicity on crustaceans.

Current Levels of Environmental Exposure to Cadmium in Industrialized Countries as a Risk Factor for Kidney Damage in the General Population: A Comprehensive Review of Available Data

The growing number of reports indicating unfavorable outcomes for human health upon environmental exposure to cadmium (Cd) have focused attention on the threat to the general population posed by this heavy metal. The kidney is a target organ during chronic Cd intoxication. The aim of this article was to critically review the available literature on the impact of the current levels of environmental exposure to this xenobiotic in industrialized countries on the kidney, and to evaluate the associated risk of organ damage, including chronic kidney disease (CKD). Based on a comprehensive review of the available data, we recognized that the observed adverse effect levels (NOAELs) of Cd concentration in the blood and urine for clinically relevant kidney damage (glomerular dysfunction) are 0.18 μg/L and 0.27 μg/g creatinine, respectively, whereas the lowest observed adverse effect levels (LOAELs) are >0.18 μg/L and >0.27 μg/g creatinine, respectively, which are within the lower range of concentrations noted in inhabitants of industrialized countries. In conclusion, the current levels of environmental exposure to Cd may increase the risk of clinically relevant kidney damage, resulting in, or at least contributing to, the development of CKD.

Physical activity mitigates the influence of blood cadmium on memory function: a cross-sectional analysis in US elderly population

Current evidence showed that heavy metal exposure including cadmium (Cd) exposure might contribute to memory function impairment in youth, while this association has not been extensively explored in senior groups. Complementary therapy like physical activity (PA) is proved to enhance memory; however, the combined effects of Cd exposure and PA are interesting issues worth investigating. Cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 were analyzed. Multivariable weighted linear regression model and restricted cubic splines analysis were used to examine the association between blood Cd, PA, and memory function. Ultimately, 1884 samples were analyzed, and the weighted participants were 98,350,183. Results showed that in the immediate and delayed recall tests, a negative association was found between blood Cd and scores for the fully adjusted model, while a positive association was detected with PA on memory test scores. In subgroup analysis, for the delayed recall test, in lower Cd exposure (Cd = Q1), stronger effect size was found in the moderate level PA group than the higher level PA group (moderate level PA group, β = 1.133, 95% CI: 0.330, 1.936; high level PA group, β = 0.203, 95% CI: - 0.314, 0.719), and this finding also existed in higher (Cd = Q4) exposure (moderate level PA group, β = 0.988, 95% CI: 0.267, 1.708; high level PA group, β = 0.830, 95% CI: 0.261, 1.400). Moreover, the non-linear relationship between Cd exposure and performance of CERAD test under different levels of PA was reported, and the moderate level PA group performed best from lower to higher blood Cd. According to our research, the benefit of PA did not always expand with the PA intensity increment under different Cd exposure. Performing an appropriate level of physical exercise could alleviate the memory decline under Cd exposure in the elder groups. Further biological investigations are warranted to verify these findings.

Integrated analysis of transcriptome-wide m6A methylation in a Cd-induced kidney injury rat model

BACKGROUND

Accumulating evidence has demonstrated that N6-methyladenosine (m⁶A) plays important roles in a variety of diseases. However, the specific functions of m⁶A in CdCl₂-induced kidney injury remain unclear.

OBJECTIVE

Here, we investigate a transcriptome-wide map of m⁶A modifications and explore the effects of m⁶A on Cd-induced kidney injury.

MATERIALS AND METHODS

The rat kidney injury model was constructed by subcutaneous injection of CdCl₂ (0.5, 1.0, and 2.0 mg/kg). The m⁶A levels were measured by colorimetry. The level of expression of m⁶A-related enzymes were detected by reverse transcription quantitative real-time PCR analysis. Transcriptome-wide m⁶A methylome in CdCl₂ (2.0 mg/kg) and the control group were profiled by methylated RNA immunoprecipitation sequencing (MeRIP-seq). Subsequently, the sequencing data were analyzed using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG), while gene set enrichment analysis (GSEA) confirmed the functional enrichment pathways of sequencing genes. In addition, a protein-protein interaction (PPI) network was applied to select hub genes.

RESULTS

The levels of m⁶A and m⁶A regulators (METTL3, METTL14, WTAP, YTHDF2) were significantly increased in CdCl₂ groups. We identified a total of 2615 differentially expressed m⁶A peaks, 868 differentially expressed genes and 200 genes with significant changes in both m⁶A modification and gene expression levels. GO, KEGG, and GSEA analyses indicated that these genes were mainly enriched in inflammation and metabolism-related pathways such as in IL-17 signaling and fatty acid metabolism. According the result of the conjoint analysis, we identified the top ten hub genes (Fos, Hsp90aa1, Gata3, Fcer1g, Cftr, Cspg4, Atf3, Cdkn1a, Ptgs2, and Npy) which may be regulated by m⁶A and involve in CdCl₂-induced kidney damage.

CONCLUSION

This study established a m⁶A transcriptional map in a CdCl₂-induced kidney injury model and suggested that m⁶A may affect CdCl₂ induced kidney injury via regulated the inflammation and metabolism related gene.

Low dosage fluorine ameliorates the bioaccumulation, hepatorenal dysfunction and oxidative stress, and gut microbiota perturbation of cadmium in rats

Many "hot spot" geographic areas around the world with soils and crops co-polluted with cadmium (Cd) and fluorine (F), two of the most representative pollutants in the environment. However, it still exists argumentative on the dose-effect relationship between F and Cd so far. To explore this, a rat model was established to evaluate the effects of F on Cd-mediated bioaccumulation, hepatorenal dysfunction and oxidative stress, and the disorder of intestinal microbiota as well. 30 healthy rats were randomly assigned to Control group (C group), Cd 1 mg/kg (Cd group), Cd 1 mg/kg and F 15 mg/kg (L group), Cd 1 mg/kg and F 45 mg/kg (M group), and Cd 1 mg/kg and F 75 mg/kg (H group) for 12 weeks by gavage. Our results showed that Cd exposure could accumulate in organs, cause hepatorenal function damage and oxidative stress, and disorder of gut microflora. However, different dosages of F showed various effects on Cd-induced damages in liver, kidney, and intestine, and only the low supplement of F showed a consistent trend. After low supplement of F, Cd levels were declined by 31.29% for liver, 18.31% for kidney, and 2.89% for colon, respectively. The serum aspartate aminotransferase (AST), blood urea nitrogen (BUN), creatinine (Cr), and N-acetyl-β-glucosaminidase (NAG) were significantly reduced (p < 0.01); The activity of superoxide dismutase (SOD) was elevated and mRNA expression level of NAD(P)H quinone oxidoreductase 1 (NQO1) was decreased in the liver and kidney (p < 0.05). Moreover, low F dosage up-regulated the abundance of Lactobacillus from 15.56% to 28.73% and the 6.23% of F/B ratio was declined to 3.70%. Collectively, this highlights that low dosage of F might be a potential strategy to ameliorate the hazardous effects by Cd-exposed in the environment.

Cadmium Disrupted ER Ca2+ Homeostasis by Inhibiting SERCA2 Expression and Activity to Induce Apoptosis in Renal Proximal Tubular Cells

Cadmium (Cd²⁺) exposure induces chronic kidney disease and renal cancers, which originate from injury and cancerization of renal tubular cells. Previous studies have shown that Cd²⁺ induced cytotoxicity by disrupting the intracellular Ca²⁺ homeostasis that is physically regulated by the endoplasmic reticulum (ER) Ca²⁺ store. However, the molecular mechanism of ER Ca²⁺ homeostasis in Cd²⁺-induced nephrotoxicity remains unclear. In this study, our results firstly revealed that the activation of calcium-sensing receptor (CaSR) by NPS R-467 could protect against Cd²⁺ exposure-induced cytotoxicity of mouse renal tubular cells (mRTEC) by restoring ER Ca²⁺ homeostasis through the ER Ca²⁺ reuptake channel sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA). Cd²⁺-induced ER stress and cell apoptosis were effectively abrogated by SERCA agonist CDN1163 and SERCA2 overexpression. In addition, in vivo, and in vitro results proved that Cd²⁺ reduced the expressions of SERCA2 and its activity regulator phosphorylation phospholamban (p-PLB) in renal tubular cells. Cd²⁺-induced SERCA2 degradation was suppressed by the treatment of proteasome inhibitor MG132, which suggested that Cd²⁺ reduced SERCA2 protein stability by promoting the proteasomal protein degradation pathway. These results suggested that SERCA2 played pivotal roles in Cd²⁺-induced ER Ca²⁺ imbalance and stress to contribute to apoptosis of renal tubular cells, and the proteasomal pathway was involved in regulating SERCA2 stability. Our results proposed a new therapeutic approach targeting SERCA2 and associated proteasome that might protect against Cd²⁺-induced cytotoxicity and renal injury.

Atorvastatin prevents cadmium-induced renal toxicity in a rat model

In many industrial processes, worker exposure to cadmium causes kidney damage; thus, protection against cadmium toxicity is important in workplace health. Cadmium toxicity involves oxidative stress by increasing the levels of reactive oxygen species. Statins have shown antioxidant effects that might prevent this increase in oxidative stress. We investigated the potential effects of atorvastatin pretreatment in protecting experimental rats against kidney toxicity caused by cadmium. Experiments were performed on 56 adult male Wistar rats (200 ± 20 g), randomly assigned to eight groups. Atorvastatin was administered by oral gavage for 15 days at 20 mg/kg/day, starting 7 days before cadmium chloride intra-peritoneal administration (at 1, 2, and 3 mg/kg) for 8 days. On day 16, blood samples were collected, and kidneys were excised to evaluate the biochemical and histopathological changes. Cadmium chloride significantly increased malondialdehyde, serum creatinine, blood urea nitrogen, and decreased superoxide dismutase, glutathione, and glutathione peroxidase levels. Pre-administration of rats with atorvastatin at a dose of 20 mg/kg decreased blood urea nitrogen, creatinine, and lipid peroxidation, increased the activities of antioxidant enzymes, and prevented changes in physiological variables compared with animals that were not pretreated. Atorvastatin pretreatment prevented kidney damage following exposure to toxic doses of cadmium. In conclusion, atorvastatin pretreatment in rats with cadmium chloride-induced kidney toxicity could reduce oxidative stress by changing biochemical functions and thereby decreasing damage to kidney tissue.

Estimation of health risks associated with dietary cadmium exposure

In much of the world, currently employed upper limits of tolerable intake and acceptable excretion of cadmium (Cd) (ECd/Ecr) are 0.83 µg/kg body weight/day and 5.24 µg/g creatinine, respectively. These figures were derived from a risk assessment model that interpreted β2-microglobulin (β2MG) excretion > 300 μg/g creatinine as a "critical" endpoint. However, current evidence suggests that Cd accumulation reduces glomerular filtration rate at values of ECd/Ecr much lower than 5.24 µg/g creatinine. Low ECd/Ecr has also been associated with increased risks of kidney disease, type 2 diabetes, osteoporosis, cancer, and other disorders. These associations have cast considerable doubt on conventional guidelines. The goals of this paper are to evaluate whether these guidelines are low enough to minimize associated health risks reliably, and indeed whether permissible intake of a cumulative toxin like Cd is a valid concept. We highlight sources and levels of Cd in the human diet and review absorption, distribution, kidney accumulation, and excretion of the metal. We present evidence for the following propositions: excreted Cd emanates from injured tubular epithelial cells of the kidney; Cd excretion is a manifestation of current tissue injury; reduction of present and future exposure to environmental Cd cannot mitigate injury in progress; and Cd excretion is optimally expressed as a function of creatinine clearance rather than creatinine excretion. We comprehensively review the adverse health effects of Cd and urine and blood Cd levels at which adverse effects have been observed. The cumulative nature of Cd toxicity and the susceptibility of multiple organs to toxicity at low body burdens raise serious doubt that guidelines concerning permissible intake of Cd can be meaningful.

Antioxidant capacity of N-acetylcysteine against the molecular and cytotoxic implications of cadmium chloride leading to hepatotoxicity and vital progression

Many studies have reported that cadmium (Cd) can induce liver cell injury; however, the toxicity mechanisms of Cd on the liver have not been fully explained. Thirty-two male albino rats were divided into four groups: the control group, the N-acetylcysteine (NAC) group orally as effervescent instant sachets with a concentration of 200 mg dissolved in distilled water and dosage was 200 mg/kg body weight freshly prepared, the cadmium chloride (CdCl₂) group (treated with 3 mg/kg orally), and the N-acetylcysteine (NAC) + cadmium chloride group (treated with 200 mg/kg orally post to CdCl₂) for 60 days. The NAC alone did not make notable changes in most of the parameters. The CdCl₂ alone, compared to control, induced significant alterations in oxidative stress markers (increment in lipid peroxidation (LPO) and nitric oxide (NO)) and antioxidant defense system (decrement in superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione peroxidase (GPx)), which resulted in a downregulation of pro-apoptotic Bcl2-associated X protein (Bax) and caspase-3 and upregulation of anti-apoptotic B-cell leukemia/lymphoma 2 (Bcl2) protein as well as the survival fate of hepatic cells. Post-administration of NAC to CdCl₂ resulted in a reduction in oxidative stress markers, shifting of cells from the G₂/M phase to the G₀/G₁ inhibiting signal-regulated kinase activation, and impairment of the anti-apoptotic signaling pathway when compared to the CdCl₂ group alone. Accordingly, the Bcl2/Bax ratio was reduced to 1.17-fold change, as an adaptive process to hepatic tissue injury. These findings demonstrated that NAC would attenuate the possibility of oxidative stress and cytotoxicity of hepatic tissue induced by CdCl₂.

Metabolome analysis reveals the toxic effects of cadmium exposure on the egg sac of spider Pardosa pseudoannulata

The investigation of the toxic effects of cadmium (Cd) on rice field invertebrates has attracted accumulating attention. Spider grants a novel insight into the impacts of Cd stress on invertebrates, but the effects of Cd-induced toxicity and molecular response mechanism of related metabolites in spider's egg sacs remain elusive. This investigation found that Cd stress distinctively decreased vitellogenin (Vg) content and hatched spiderlings numbers in the egg sac of Pardosa pseudoannulata. In addition, Cd stress exerted oxidative stress in the egg sac, manifested as the increase of superoxide dismutase and malondialdehyde levels. Further results showed that Cd exposure could affect egg sacs' energy metabolism, including protein and lipid contents. Metabolome analysis generated 73 up-regulated and 63 down-regulated differentially expressed metabolites (DEMs), mainly affecting phenylalanine metabolism, alpha-linolenic acid metabolism, pentose phosphate pathway, and biosynthesis of amino acids. Specifically, pathway analysis showed that Cd exposure down-regulated several key factors, including tyrosine, L-phenylalanine, O-phospho-L-serine, and L-cystathionine, and inhibited the metabolism of amino acids in the egg sacs. The subsequent correlation analysis found that three metabolite indicators, 9-Oxo-ODE, PG (17:0/18:2), and PE (17:0/20:5), were the dominant contributors to the egg sec's properties (i.e., Vg content and gained spiderlings). Collectively, this study hopes to provide valuable data for the protection of rice field spiders and offer novel perspectives for Cd pollution assessment and management.

Renal glucose transporters play a role in removal of cadmium from kidney cells mediated by GMDTC - A novel metal chelator

Cadmium (Cd) is a toxic heavy metal, exposure to which leads to adverse health effects including chronic kidney damage. Tremendous efforts have been explored in identifying safe chelating agents for removing accumulated Cd from kidney, but with limited success owing to their associated side effects and the ineffectiveness in eliminating Cd. A newly developed chelating agent, sodium (S)-2-(dithiocarboxylato((2S,3 R,4R,5 R)-2,3,4,5,6-pentahydroxyhexyl) amino)-4(methylthio)butanoate (GMDTC), has been shown to effectively mobilize Cd from kidney. However, the mechanism(s) of removal are unclear, while it has been hypothesized that renal glucose transporters potentially play key roles mainly because GMDTC contains an open chain glucose moiety. To test this hypothesis, we utilized the CRISPR/Cas9 technology and human kidney tubule HK-2 cells, and constructed sodium-dependent glucose transporter 2 (SGLT2) or glucose transporter 2 (GLUT2) gene knockout cell lines. Our data showed that GMDTC's ability in removing Cd from HK-2 cells was significantly reduced both in GLUT2^-/- or SGLT2^-/- cells, with a removal ratio reduced from 28.28% in the parental HK-2 cells to 7.37% in GLUT2^-/- cells and 14.6% in SGLT2^-/- cells. Similarly, knocking out the GLUT2 or SGLT2 led to a compromised protective effect of GMDTC in reducing cytotoxicity of HK-2 cells. This observation was further observed in animal studies, in which the inhibition of GLUT2 transporter by phloretin treatment resulted in reduced efficiency of GMDTC in removing Cd from the kidney. Altogether, our results show that GMDTC is safe and highly efficient in removing Cd from the cells, and this effect is mediated by renal glucose transporters.

Interspecies differences in mammalian susceptibility to legacy POPs and trace metals using skin fibroblast cells

The susceptibility to trace metals and legacy POPs is different between terrestrial and marine mammals. In this study, we established the first cell line from Indo-Pacific finless porpoises and compared the cellular responses of skin fibroblast cells from Pygmy killer whales, Pantropic spotted dolphins, Indo-Pacific finless porpoises, mice, and humans following exposure to copper, methylmercury, cadmium, PCB126, PCB153, and BDE47 to better understand the interspecies sensitivities of mammals to chemical pollutants. We conducted a risk assessment by comparing no-observed effect concentrations (NOEC), lowest-observed effect concentrations (LOEC), and half maximal effective concentrations (EC50) from cell viability assays and previously reported pollutant body burdens in mammals. Based on the in vitro data, Indo-Pacific finless porpoises were more sensitive to copper and methylmercury than other mammals. PCB153 exposure reduced cell viability in all mammals except humans, while PCB126 was more potent, with 13.33 μg/mL exposure reducing cell viability in all mammals. In contrast, BDE47 exposure reduced cell viability only in terrestrial mammals in addition to pantropic spotted dolphin. Based on the in vitro data and the natural context of metal concentrations, both methylmercury and cadmium posed a higher risk to cetaceans than human, while copper posed a lower risk to cetaceans. All three legacy POPs (PCB126, PCB153, and BDE47) posed minor risk to cetaceans for short-term exposure. This study demonstrated that a species-specific in vitro model may provide more accurate information on the potential risk of pollutants to mammals. However, due to the bioamplification of POPs and their potential impact on the endocrine system and immune system of cetaceans, risk assessment with long-term exposure with more in vitro models should be further studied.

Editing of a Novel Cd Uptake-Related Gene CUP1 Contributes to Reducing Cd Accumulations in Arabidopsis thaliana and Brassica napus

Brassica napus is a Cd hyperaccumulator, which is a serious threat to food and fodder safety. However, no related studies on developing Cd-safe B. napus have been reported yet. Here, we screened out a novel Cd uptake-related gene, AtCUP1, from the major facilitator superfamily in Arabidopsis thaliana. The mutation of AtCUP1 decreased Cd accumulation, both in roots and shoots of A. thaliana. Furthermore, the disruption of the AtCUP1 gene by the CRISPR/Cas9 system significantly reduced Cd accumulation in A. thaliana. Interestingly, the disruption of the BnCUP1 gene, an orthologous gene of AtCUP1, by the CRISPR/Cas9 system also diminished Cd accumulation in both roots and shoots of B. napus based on the hydroponics assay. Furthermore, for the field experiment, the Cd accumulations of BnCUP1-edited lines were reduced by 52% in roots and 77% in shoots compared to that of wild-type (WT) lines, and the biomass and yield of BnCUP1-edited lines increased by 42% and 47% of that of WT, respectively. Noteworthily, agronomic characteristics of B. napus were not apparently affected by BnCUP1-editing. Thus, BnCUP1-edited lines are excellent non-transgenic germplasm resources for reducing Cd accumulation without a distinct compromise in yield, which could be applied to agricultural production in Cd-contaminated soils.

Epigenetic mechanisms of cadmium-induced nephrotoxicity

Cadmium (Cd) is a widespread toxic pollutant that affects millions of individuals worldwide. Cd exposure in humans occurs primarily through consumption of contaminated food and water, cigarette smoking, and industrial applications. The kidney proximal tubular (PT) epithelial cells are the primary target of Cd toxicity. Cd-induced injury to PT cells impedes tubular reabsorption. Despite the many long-term sequelae of Cd exposure, molecular mechanisms of Cd toxicity are poorly understood, and no specific therapies exist to mitigate the effects of Cd exposure. In this review, we summarize recent work linking Cd-mediated damage to epigenetic perturbations - DNA methylation, and levels of histone modifications, including methylation and acetylation. New insights into the links between Cd intoxication and epigenetic damage will contribute to an improved understanding of Cd's pleiotropic impacts on cells, and perhaps lead to new, mechanism-based treatments for this condition.

Metabolic effects of long-term cadmium exposure: an overview

Cadmium (Cd) is a toxic non-essential heavy metal. Chronic low Cd exposure (CLCE) has been associated with distinct pathologies in many organ systems, including liver and kidney damage, osteoporosis, carcinogenicity, or reproductive toxicity. Currently, about 10% of the global population is at risk of CLCE. It is urgent to find robust and effective biomarkers for early diagnosis of Cd exposure and treatment. Metabolomics is a high-throughput method based on mass spectrometry to study the dynamic changes in a series of endogenous small molecular metabolites (typically < 1000 Da) of tissues, cells, or biofluids. It can reflect the rich and complex biochemical changes in the body after exposure to heavy metals, which may be useful in screening biomarkers to monitor exposure to environmental pollutants and/or predict disease risk. Therefore, this review focuses on the changes in metabolic profiles of humans and rodents under long-term Cd exposure from the perspective of metabolomics. Furthermore, the relationship between the disturbance of metabolic pathways and the toxic mechanism of Cd is discussed. All these information will facilitate the development of reliable metabolic biomarkers for early detection and diagnosis of Cd-related diseases.

Sirtuin-1 attenuates cadmium-induced renal cell senescence through p53 deacetylation

Cadmium (Cd), the common environmental pollutant, primarily targets at renal proximal tubules and induces nephrotoxicity. Cellular senescence, a phenomenon of cell growth arrest and a characteristics of maladaptive cell self-repair, is associated with renal disease progression. However, whether and how Cd induces renal tubular cells premature senescence is unknown. In our study, we found that Cd induced kidney damage and dysfunctions, which correlated with exacerbated tubular cell senescence, evidenced by increased senescence-associated β-galactosidase activity, the upregulated protein expression of p53 and p21^Waf1/Cip1 proteins, and elevated expression and secretion of cytokines in human proximal tubular epithelial HK-2 cells in vitro and in Cd-treated mice in vivo. Moreover, a S-phase arrest and decrease in Edu positive rate were found in Cd-treated HK-2 cells. Mechanistically, Cd suppressed the expression and activity of Sirtuin-1 (SIRT1), an anti-senescence deacetylase, resulting in the accumulation of acetylated p53 and upregulation of p21^Waf1/Cip1. Activation of SIRT1 significantly abolished Cd-induced premature senescence and S-phase arrest. Finally, silencing p21^Waf1/Cip1 efficiently delayed premature senescence and recovered cell cycle progression. These findings indicate that Cd promotes tubular cells senescence and impairs tubular cells regeneration, resulting in kidney dysfunctions, which could be ameliorated by SIRT1 activation.

Protective Effects of Astilbin Against Cadmium-Induced Apoptosis in Chicken Kidneys via Endoplasmic Reticulum Stress Signaling Pathway

Cadmium (Cd) can cause endoplasmic reticulum stress (ERS) and apoptosis in animals. The kidney is an organ seriously affected by Cd because it can accumulate metal ions. Astilbin (ASB) is a dihydroflavonol rhamnoside, which has an anti-renal injury effect. This study aimed to evaluate the protective effect of ASB on Cd-induced ERS and apoptosis in the chicken kidney. In this study, a total of 120 1-day-old chickens were randomly divided into 4 groups. Chickens were fed with a basic diet (Con group), ASB 40 mg/kg (ASB group), CdCl₂ 150 mg/kg + ASB 40 mg/kg (ASB/Cd group), and CdCl₂ 150 mg/kg (Cd group) for 90 days. The results showed that Cd exposure induced pathological and ultrastructural damages and apoptosis in chicken kidneys. Compared with the Con group, metallothionein (MT1/MT2) level, nitric oxide (NO) content, inducible nitric oxide synthase (iNOS) activity, ERS-related genes 78-kDa glucose-regulated protein (Grp78), protein kinase PKR-like endoplasmic reticulum kinase (Perk), activating transcription factor 4 (Atf4) and CAAT/enhancer-binding protein (C/EBP) homologous protein (Chop), and pro-apoptotic gene B-cell lymphoma 2 (Bcl-2)-associated X (Bax), caspase-12, caspase-9, caspase-3 expression levels, and apoptotic rate were significantly increased in the Cd group. The expression level of Bcl-2 was significantly decreased in the Cd group. ASB/Cd combined treatment significantly improves the damage of chicken kidneys by ameliorating Cd-induced kidney ERS and apoptosis. Cd can cause the disorder of the GRP78 signal axis, activate the PERK-ATF4-CHOP pathway, aggravate the structural damage and dysfunction of ER, and promote the apoptosis of chicken kidneys, while the above changes were significantly alleviated in the ASB/Cd group. The results showed that ASB antagonizes the negative effects of Cd and against Cd-induced apoptosis in chicken kidneys via ERS signaling pathway.

Alterations at biochemical, proteomic and transcriptomic levels in liver of tilapia (Oreochromis niloticus) under chronic exposure to environmentally relevant level of glyphosate

The toxicity of glyphosate (Gly) on aquatic animals has received attention from many researchers. However, the chronic toxicity mechanism of Gly on fish has not yet been clarified entirely. Thus, this study aimed to explore the potential toxicity mechanism of Gly at 2 mg/L, a possibly existing concentration in the aquatic environment, via biochemical, transcriptomic and proteomic analyses in the liver of tilapia. Long-term Gly exposure increased lipid content, and altered redox status in liver. Transcriptomic analysis revealed that Gly exposure changed dramatically the expression of 225 genes in liver, including 94 up-regulated genes and 131 down-regulated genes. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analyses showed that these genes were predominantly enriched in ion transport, lipid metabolism and PPAR (peroxisome proliferator-activated receptor) signaling pathway. Meanwhile, at proteomic level, long-term Gly exposure resulted in alteration of 21 proteins, which were principally related to hepatic metabolism function. In conclusion, our data displayed a potential toxicity, mainly manifested as redox imbalance and dysregulation of metabolism function, in the liver of tilapia after long-term Gly exposure at 2 mg/L. This study provided novel insight into underlying toxicity mechanism of long-term Gly exposure at an environmentally relevant concentration in fish.

Saffron nephroprotective effects against medications and toxins: A review of preclinical data

Toxin and drug-induced nephrotoxicity (DIN) account for about 25% of all acute kidney injury cases and are associated with morbidity and increased utilization of healthcare services. No approved preventive compound is available for DIN. Saffron (Crocus sativus) has important biological properties like antioxidant and anti-inflammatory effects. The protective effects of saffron and its main constituents in different tissues including the brain, heart, liver, kidney, and lung have been confirmed against some toxic materials or drugs in animal studies. This review covers all aspects of saffron’s preventive and therapeutic effects against toxins and DIN including proposed mechanism of action, dosing schedule, and effects on renal biomarkers and histological changes. PubMed, Embase, Scopus, and Web of Science databases were searched by these search terms: “saffron” OR “Crocus sativus” OR “crocetin” OR “crocin “OR “safranal” AND “Drug induced nephrotoxicity” OR “Renal Injury” OR “Kidney Injury” OR “Nephrotoxicity”. All 25 relevant in vitro and in vivo studies up to the date of publication were included. Promising protective effects were reported particularly on aminoglycosides, cisplatin, and ethanol. Saffron and its constituents significantly prevented biochemical and histopathological changes, mediating via antioxidant, anti-apoptosis, and anti-inflammatory effects. Despite success in animal models, no human study is available in this field and further well-designed clinical trials are necessary for better judgment.

Cadmium acute exposure induces metabolic and transcriptomic perturbations in human mature adipocytes

Obesity is considered as a major public health concern with strong economic and social burdens. Exposure to pollutants such as heavy metals can contribute to the development of obesity and its associated metabolic disorders, including type 2 diabetes and cardiovascular diseases. Adipose tissue is an endocrine and paracrine organ that plays a key role in the development of these diseases and is one of the main target of heavy metal accumulation. In this study, we determined by inductively coupled plasma mass spectrometry cadmium concentrations in human subcutaneous and visceral adipose tissues, ranging between 2.5nM and 2.5µM. We found a positive correlation between cadmium levels and age, sex and smoking status and a negative correlation between Cd and body mass index. Based on cadmium adipose tissue concentrations found in humans, we investigated the effects of cadmium exposure, at concentrations between 1nM and 10µM, on adipose-derived human mesenchymal stem cells differentiated into mature adipocytes in vitro. Transcriptomic analysis highlighted that such exposure altered the expression of genes involved in trace element homeostasis and heavy metal detoxification, such as Solute Carrier Family transporters and metallothioneins. This effect correlated with zinc level alteration in cells and cellular media. Interestingly, dysregulation of zinc homeostasis and transporters has been particularly associated with the development of obesity and type 2 diabetes. Moreover, we found that cadmium exposure induces the pro-inflammatory state of the adipocytes by enhancing the expression of genes such as IL-6, IL-1B and CCL2, cytokines also induced in obesity. Finally, cadmium modulates various adipocyte functions such as the insulin response signaling pathway and lipid homeostasis. Collectively, our data identified some of the cellular mechanisms by which cadmium alters adipocyte functions, thus highlighting new facets of its potential contribution to the progression of metabolic disorders.

Myo-inositol oxygenase overexpression exacerbates cadmium-induced kidney injury via oxidant stress and necroptosis

Conceivably, like other forms of acute kidney injury, cadmium-induced renal injury may also be associated with oxidative stress and various forms of cell death, including necroptosis, a form of regulated necrosis-associated cell death. Myo-inositol oxygenase (MIOX), an enzyme localized in renal proximal tubules, regulates oxidative stress and programmed cell death in various forms of renal injuries. Herein, the role and potential mechanism(s) by which MIOX potentiates cadmium-induced renal tubular damage were investigated. Overexpression of MIOX exacerbated cadmium-induced cell death and proximal tubular injury in mice, whereas MIOX gene disruption attenuated cellular damage in vitro and in vivo. Furthermore, necroptosis was observed in the renal tubular compartment, and, more importantly, it was corroborated by inhibitor experiments with necrostatin-1 (Nec-1). Coadministration of Nec-1 dampened including receptor-interacting protein kinase (RIP)1/RIP3/mixed-lineage kinase domain-like signaling, which is relevant to the process of necroptosis. Interestingly, the necroptosis induced by cadmium in tubules was modulated by MIOX expression profile. Also, the increased reactive oxygen species generation and NADPH consumption were accelerated by MIOX overexpression, and they were mitigated by Nec-1 administration. These findings suggest that MIOX-potentiated redox injury and necroptosis are intricately involved in the pathogenesis of cadmium-induced nephropathy, and this may yield novel potential therapeutic targets for amelioration of cadmium-induced kidney injury.NEW & NOTEWORTHY This is a seminal article documenting the role of myo-inositol oxygenase (MIOX), a renal proximal tubule-specific enzyme, in the exacerbation of cadmium-induced acute kidney injury by perturbing redox balance and inducing necroptosis. MIOX gene disruption or administration of necrostatin-1 (a necroptosis inhibitor) diminished cadmium-induced renal damage, in both in vitro and in vivo systems, suggesting a therapeutic potential of MIOX to attenuate necroptosis and relevant signaling pathways in cadmium-induced renal injury.

Effect of heavy metals on epididymal morphology and function: An integrative review

Male fertility has deteriorated over the last decades, and environmental risk factors are among the possible causes of this phenomenon. Pollutants such as heavy metals might accumulate in male reproductive organs to levels that are associated with reproductive disorders. Several studies reported detrimental effects of inorganic arsenic (iAs⁺³/iAs⁺⁵), cadmium (Cd⁺²), lead (Pb⁺²), and mercury (Hg⁺²/CH₃Hg⁺²) on the epididymis, which plays a crucial role in sperm maturation. However, the magnitude of their effects and the consequences on the physiology of the epididymis are still unclear. Therefore, an integrative review with meta-analyses was conducted examining 138 studies to determine how exposure to arsenic, cadmium, lead, and mercury affects epididymal morphology and functions, using primarily murine data from experimental studies as a source. This study showed that exposure to metal(loids) reduced epididymal weight, sperm motility, and sperm number. Inorganic arsenic, cadmium, and lead damaged sperm structures within the epididymal duct. While sodium arsenite, sodium arsenate, and lead acetate generate oxidative stress by an imbalance between ROS production and scavenging, cadmium chloride causes an increase in the pH level of the luminal fluid (from 6.5 to 7.37) that diminishes sperm viability. Inorganic arsenic induced a delay in the sperm transit time by modulating noradrenaline and dopamine secretion. Subacute exposure to heavy metals at concentrations < 0.1 mg L^-1 initiates a dyshomeostasis of calcium, copper, iron, and zinc that disturbs sperm parameters and reduces epididymal weight. These alterations worsen with prolonged exposure time and higher doses. Most studies evaluated the effects of concentrations > 1.1 mg L^-1 of heavy metals on the epididymis rather than doses with relevant importance for human health risk. This meta-analytical study faced limitations regarding a deeper analysis of epididymis physiology. Hence, several recommendations for future investigations are provided. This review creates a baseline for the comprehension of epididymal toxicology.

The Hippo pathway kinases LATS1 and LATS2 attenuate cellular responses to heavy metals through phosphorylating MTF1

Heavy metals are both integral parts of cells and environmental toxicants, and their deregulation is associated with severe cellular dysfunction and various diseases. Here we show that the Hippo pathway plays a critical role in regulating heavy metal homeostasis. Hippo signalling deficiency promotes the transcription of heavy metal response genes and protects cells from heavy metal-induced toxicity, a process independent of its classic downstream effectors YAP and TAZ. Mechanistically, the Hippo pathway kinase LATS phosphorylates and inhibits MTF1, an essential transcription factor in the heavy metal response, resulting in the loss of heavy metal response gene transcription and cellular protection. Moreover, LATS activity is inhibited following heavy metal treatment, where accumulated zinc directly binds and inhibits LATS. Together, our study reveals an interplay between the Hippo pathway and heavy metals, providing insights into this growth-related pathway in tissue homeostasis and stress response.

The associations between urinary metals and metal mixtures and kidney function in Chinese community-dwelling older adults with diabetes mellitus

BACKGROUND

Previous studies have found associations between single toxic metals, such as arsenic and cadmium, and kidney function in adults with diabetes. However, studies with regards to other metals and metal mixtures are still limited.

OBJECTIVE

Our study aimed to investigate the associations between urinary concentrations of 5 selected metals and metal mixtures and kidney function using a sample of older adults with diabetes mellitus in Chinese communities.

METHODS

In a sample of older adults (n = 5186), 592 eligible subjects were included in this study. Urinary concentrations of 5 metals, i.e., arsenic (As), cadmium (Cd), vanadium (V), cobalt (Co), and thallium (Tl), were measured by inductively coupled plasma mass spectrometer (ICP-MS). Estimated glomerular filtration rate (eGFR) was calculated and dichotomized into indicator of chronic kidney disease (CKD). Logistic analysis and Bayesian kernel machine regression (BKMR) were used to explore the associations between single metals and metal mixtures and CKD, respectively.

RESULTS

Urinary levels of As and V were positively correlated with CKD (OR=2.37, 95% CI: 1.31-4.30 for As; OR=2.24, 95% CI: 1.25-4.03 for V), when compared the 4th quartile with the 1st quartile. After adjustment for potential confounders, the significant association between As and CKD still existed (OR=2.73, 95% CI: 1.23-6.07). BKMR analyses showed strong linear positive associations between As and V and CKD. Higher urinary levels of the mixture were significantly associated with higher odds of CKD in a dose-response pattern. As and V showed the highest posterior inclusion probabilities.

CONCLUSION

Urine As and V were positively associated with CKD in older adults with diabetes mellitus, separately and in a mixture. The metals mixture showed a linear dose-response association with the odds of CKD. The analyses of mixtures, rather than of single metals, may provide a real-world perspective on the relationship between metals and kidney function.

Cadmium exposure induces osteoporosis through cellular senescence, associated with activation of NF-κB pathway and mitochondrial dysfunction

Cadmium (Cd) is a heavy metal toxicant as a common pollutant derived from many agricultural and industrial sources. The absorption of Cd takes place primarily through Cd-contaminated food and water and, to a significant extent, via inhalation of Cd-contaminated air and cigarette smoking. Epidemiological data suggest that occupational or environmental exposure to Cd increases the health risk for osteoporosis and spontaneous fracture such as itai-itai disease. However, the direct effects and underlying mechanism(s) of Cd exposure on bone damage are largely unknown. We used primary bone marrow-derived mesenchymal stromal cells (BMMSCs) and found that Cd significantly induced BMMSC cellular senescence through over-activation of NF-κB signaling pathway. Increased cell senescence was determined by production of senescence-associated secretory phenotype (SASP), cell cycle arrest and upregulation of p21/p53/p16^INK4a protein expression. Additionally, Cd impaired osteogenic differentiation and increased adipogenesis of BMMSCs, and significantly induced cellular senescence-associated defects such as mitochondrial dysfunction and DNA damage. Sprague-Dawley (SD) rats were chronically exposed to Cd to verify that Cd significantly increased adipocyte number, and decreased mineralization tissues of bone marrow in vivo. Interestingly, we observed that Cd exposure remarkably retarded bone repair and regeneration after operation of skull defect. Notably, pretreatment of melatonin is able to partially prevent Cd-induced some senescence-associated defects of BMMSCs including mitochondrial dysfunction and DNA damage. Although Cd activated mammalian target of rapamycin (mTOR) pathway, rapamycin only partially ameliorated Cd-induced cell apoptosis rather than cellular senescence phenotypes of BMMSCs. In addition, a selective NF-κB inhibitor moderately alleviated Cd-caused the senescence-related defects of the BMMSCs. The study shed light on the action and mechanism of Cd on osteoporosis and bone ageing, and may provide a novel option to ameliorate the harmful effects of Cd exposure.

Cadmium induces renal inflammation by activating the NLRP3 inflammasome through ROS/MAPK/NF-κB pathway in vitro and in vivo

Cadmium (Cd) has been reported to induce kidney damage by triggering oxidative stress and inflammation. The NLR family Pyrin Domain Containing 3 (NLRP3) inflammasome has been implicated a role in the pathogenesis of inflammation. However, the connection between Cd and NLRP3 inflammasome in the development of renal inflammation remains unknown. In this study, in vitro experiments based on the telomerase-immortalized human renal proximal-tubule epithelial cell line (RPTEC/TERT1) were carried out. Results revealed that CdCl2 (2-8 μM) increased ROS production and activated NLRP3, thereby enhancing secretion of IL-1β and IL-18 (P < 0.05). Knock-down of NLRP3 rescued the RPTEC/TERT1 cells from Cd-induced inflammatory damage. Cd activated the MAPK/NF-κB signaling pathway in RPTEC/TERT1 cells (P < 0.05). In addition, treatment with N-acetylcysteine (NAC) improved inflammation and blocked the upregulation of the MAPK/NF-κB signaling pathway. Pre-treatment with MAPK and NF-κB inhibitors also suppressed NLRP3 inflammasome activation (P < 0.05). Moreover, CdCl2 (25-00 mg/L) stimulated the MAPK/NF-κB signaling pathway, activated the NLRP3 inflammasome, and increased inflammatory response (P < 0.05) leading to renal injury in rats. Exposure to cadmium elevated serum levels of NLRP3 and IL-1β in populations (P < 0.05). Further analysis found that serum NLRP3 and IL-1β levels were positively correlated with urine cadmium (UCd) and urine N-acetyl-β-D-glucosaminidase (UNAG). Overall, Cd induced renal inflammation through the ROS/MAPK/NF-κB signaling pathway by activating the NLRP3 inflammasome. Our research thus provides new insights into the molecular mechanism that NLRP3 contributes to Cd-induced kidney damage.

Transcription profiling of cadmium-exposed livers reveals alteration of lipid metabolism and predisposition to hepatic steatosis

1. Cadmium (Cd) is a ubiquitous environmental toxicant that can cause liver steatosis and nonalcoholic fatty liver disease (NAFLD) on long-term exposure.2. Sixteen Sprague Dawley rats were randomly divided into two groups, and were administered normal saline and 5 mg/(kg·d) cadmium chloride by gavage. In vitro, BRL3A cells, a rat normal liver cell line, were treated with different concentrations of Cd to verify the sequencing results.3. The RNA-seq revealed 146 upregulated genes and 127 downregulated genes in the Cd intervention group. The key genes of lipid metabolism were significantly overexpressed, such as Cyp1a1 and Pla2g2d. The GO enrichment analysis showed that the 'sterol biosynthetic process' was the most obvious difference. The KEGG analysis showed that six of the top 10 differential pathways were related to lipid metabolism. The expression of the essential genes in BRL3A was consistent with the sequencing results. The protein-protein interaction (PPI) yielded that Cyp1a1 is in the central region of the differentially expressed gene network.4. The chronic Cd exposure is still an important environmental health problem with a probable tendency to cause NAFLD. It may possibly act by affecting the lipid metabolism in the liver, especially the synthesis and decomposition of unsaturated fatty acids.