Cadmium and High-Fat Diet Disrupt Renal, Cardiac and Hepatic Essential Metals

Potential pathogenic roles of ferroptosis and cuproptosis in cadmium-induced or exacerbated cardiovascular complications in individuals with diabetes

Diabetes and its complications are major diseases that affect human health. Diabetic cardiovascular complications such as cardiovascular diseases (CVDs) are the major complications of diabetes, which are associated with the loss of cardiovascular cells. Pathogenically the role of ferroptosis, an iron-dependent cell death, and cuproptosis, a copper-dependent cell death has recently been receiving attention for the pathogenesis of diabetes and its cardiovascular complications. How exposure to environmental metals affects these two metal-dependent cell deaths in cardiovascular pathogenesis under diabetic and nondiabetic conditions remains largely unknown. As an omnipresent environmental metal, cadmium exposure can cause oxidative stress in the diabetic cardiomyocytes, leading to iron accumulation, glutathione depletion, lipid peroxidation, and finally exacerbate ferroptosis and disrupt the cardiac. Moreover, cadmium-induced hyperglycemia can enhance the circulation of advanced glycation end products (AGEs). Excessive AGEs in diabetes promote the upregulation of copper importer solute carrier family 31 member 1 through activating transcription factor 3/transcription factor PU.1, thereby increasing intracellular Cu+ accumulation in cardiomyocytes and disturbing Cu+ homeostasis, leading to a decline of Fe-S cluster protein and reactive oxygen species accumulation in cardiomyocytes mitochondria. In this review, we summarize the available evidence and the most recent advances exploring the underlying mechanisms of ferroptosis and cuproptosis in CVDs and diabetic cardiovascular complications, to provide critical perspectives on the potential pathogenic roles of ferroptosis and cuproptosis in cadmium-induced or exacerbated cardiovascular complications in diabetic individuals.

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.

Attenuation of inflammation, oxidative stress and TGF-β1/Smad3 signaling and upregulation of Nrf2/HO-1 signaling mediate the protective effect of diallyl disulfide against cadmium nephrotoxicity

Heavy metals are toxic environmental pollutants with serious health effects on humans and animals. Cadmium (Cd) is known for its serious nephrotoxic effect and its toxicity involves oxidative stress (OS) and inflammation. Diallyl disulfide (DADS), a main constituent of garlic, exhibites cytoprotective and antioxidant activities. This study investigated the effect of DADS on OS, inflammation, and fibrosis induced by Cd in rat kidney, pointing to the involvement of transforming growth factor-β (TGF-β)/Smad3 and nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling, and peroxisome proliferator-activated receptor gamma (PPARγ). Rats received DADS for 14 days and Cd on day 7 and blood and kidney samples were collected. Cd elevated serum creatinine, urea and uric acid, provoked kidney histopathological alterations and collagen deposition, increased kidney malondialdehyde (MDA) level, and decreased glutathione (GSH) and antioxidant enzymes. Nuclear factor-kappaB (NF-κB) p65, interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-1β, and CD68 were upregulated in Cd-administered rat kidney. DADS prevented kidney injury, mitigated OS, suppressed NF-κB, CD68 and pro-inflammatory mediators, and boosted antioxidants. DADS downregulated TGF-β1, Smad3 phosphorylation and Kelch-like ECH-associated protein-1 (Keap1), and increased Nrf2, HO-1, cytoglobin, and PPARγ. In conclusion, DADS protects the kidney against Cd toxicity by attenuating OS, inflammation, and TGF-β1/Smad3 signaling, and enhancement of Nrf2/HO-1 signaling, antioxidants, and PPARγ.

Alleviation of Lipid Disorder and Liver Damage in High-Fat Diet-Induced Obese Mice by Selenium-Enriched Cardamine violifolia with Cadmium Accumulation

BACKGROUND/OBJECTIVES

As a hyperaccumulator of selenium (Se), Cardamine violifolia (Cv) and its peptide extract could ameliorate the negative effects of a high-fat diet (HFD). However, the effects of the coaccumulation of cadmium (Cd) in Se-enriched Cv (Cv2) and the potential confounding effect on the roles of enriched Se remain unknown. We aimed to investigate whether Cv2 could alleviate HFD-induced lipid disorder and liver damage.

METHODS

Three groups of 31-week-old female mice were fed for 41 weeks (n = 10-12) with a control Cv-supplemented diet (Cv1D, 0.15 mg Se/kg, 30 µg Cd/kg, and 10% fat calories), a control Cv-supplemented HFD (Cv1HFD, 45% fat calories), and a Cv2-supplemented HFD (Cv2HFD, 1.5 mg Se/kg, 0.29 mg Cd/kg, and 45% fat calories). Liver and serum were collected to determine the element concentrations, markers of liver injury and lipid disorder, and mRNA and/or protein expression of lipid metabolism factors, heavy metal detoxification factors, and selenoproteins.

RESULTS

Both Cv1HFD and Cv2HFD induced obesity, and Cv2HFD downregulated Selenoi and upregulated Dio3 compared with Cv1D. When comparing Cv2HFD against Cv1HFD, Cv2 increased the liver Se and Cd, the protein abundance of Selenoh, and the mRNA abundance of 10 selenoproteins; reduced the serum TG, TC, and AST; reduced the liver TG, lipid droplets, malondialdehyde, and mRNA abundance of Mtf1 and Mt2; and differentially regulated the mRNA levels of lipid metabolism factors.

CONCLUSIONS

Cv2 alleviated HFD-induced lipid dysregulation and liver damage, which was probably associated with its unique Se speciation. However, further research is needed to explore the interaction of plant-coenriched Se and Cd and its effects on health.

Adolescent co-exposure to environmental cadmium and high-fat diet induces cognitive decline via Larp7 m6A-mediated SIRT6 inhibition

The effects and underlying mechanisms of adolescent exposure to combined environmental hazards on cognitive function remain unclear. Here, using a combined exposure model, we found significant cognitive decline, hippocampal neuronal damage, and neuronal senescence in mice exposed to cadmium (Cd) and high-fat diet (HFD) during adolescence. Furthermore, we observed a significant downregulation of Sirtuin 6 (SIRT6) expression in the hippocampi of co-exposed mice. UBCS039, a specific SIRT6 activator, markedly reversed the above adverse effects. Further investigation revealed that co-exposure obviously reduced the levels of La ribonucleoprotein 7 (LARP7), disrupted the interaction between LARP7 and SIRT6, ultimately decreasing SIRT6 expression in mouse hippocampal neuronal cells. Overexpression of Larp7 reversed the combined exposure-induced SIRT6 decrease and senescence in mouse hippocampal neuronal cells. Additionally, the results showed notably elevated levels of Larp7 m6A and YTH domain family protein 2 (YTHDF2) in mouse hippocampal neuronal cells treated with the combined hazards. Ythdf2 short interfering RNA, RNA immunoprecipitation, and RNA stability assays further demonstrated that YTHDF2 mediated the degradation of Larp7 mRNA under combined exposure. Collectively, adolescent co-exposure to Cd and HFD causes hippocampal senescence and cognitive decline in mice by inhibiting LARP7-mediated SIRT6 expression in an m6A-dependent manner.

Polystyrene nanoplastics and cadmium co-exposure aggravated cardiomyocyte damage in mice by regulating PANoptosis pathway

Micro/nanoplastics (M/NPs) are the novel contaminants ubiquitous in the environment. Cadmium (Cd), a kind of heavy metal pollutant widely distributed, could potentially co-exist with PS-NPs in the environment. However, their combined effects on cardiomyocyte and its molecular mechanism in mammals remained ambiguous. Here, we examined whether PANoptosis, an emerging and complicated kind of programmed cell death, was involved in PS-NPs and Cd co-exposure-elicited cardiac injury. In this study, 60 male mice were orally subjected to environmentally relevant concentrations of PS-NPs (1 mg/kg) and/or CdCl2 (1.5 mg/kg) for 35 days. As we speculated, PS-NPs and Cd co-exposure affected the expression of pyroptosis(Caspase-1, Cleaved-Caspase-1, GSDMD, N-GSDMD, AIM2, Pyrin, NLRP3, IL-18, IL-1β)-, apoptosis(Caspase-3, Cleaved-Caspase-3, Caspase-8, Cleaved-Caspase-8, Caspase-7, BAX)- and necroptosis (t-RIPK3, p-RIPK3, t-RIPK1, p-RIPK1, t-MLKL, p-MLKL, ZBP1)-related genes and protein, resulting in growth restriction and damaged myocardial microstructure in mice. Notably, the combined effects on Cd and PS-NPs even predominantly aggravated the toxic damage. Intriguingly, we fortuitously discovered PS-NPs and/or Cd exposure facilitated linear ubiquitination of certain proteins in mice myocardium. In summation, this study shed light toward the effects of Cd and PS-NPs on cardiotoxicity, advanced the understanding of myocardial PANoptosis and provided a scientific foundation for further exploration of the combined toxicological effects of PS-NPs and heavy metals.

Levels and Health Risk Assessment of Inorganic Arsenic, Methylmercury, and Heavy Metals in Edible Mushrooms Collected from Online Supermarket in China

Chromium (Cr), total arsenic (As), inorganic arsenic (iAs), cadmium (Cd), mercury (Hg), methylmercury (MeHg), and lead (Pb) were analyzed in in Agaricus blazei, Tricholoma matsutake, Pholiota nameko, agrocybe aegirit, Boletus edulis, Auricularia auricula, and Lentinus edodes collected from online supermarket in China from 2015 to 2017. The order of mean concentrations for the five heavy metals in edible mushrooms was As > Cd > Cr > Pb > Hg. No positive correlation was found between total As and iAs, nor between total Hg and MeHg. The contents of iAs were at a low level except for A. blazei samples. The contents of MeHg were at a low level in all test mushroom samples. And Cr, Cd, and Pb pollution were common problems in the test mushroom samples. The comprehensive factor pollution index was between 0.569 (A. auricula) and 3.056 (B. edulis). The THQ values for the five heavy metals from P. nameko, A. auricula, A. aegirit, and L. edodes samples were less than 1. The hazard index (HI) values of A. blazei, T. matsutake, and B. edulis samples for adults and children were greater than 1, indicating significant health hazard to the adults and children consumers. The cancer risk (CR) values for iAs ranged from 3.82 × 10- 6 (T. matsutake) to 8.61 × 10- 5 (A. blazei), indicating no potential carcinogenic risk to the consumers. The order for carcinogenic risk of each edible mushroom species was A. blazei > L. edodes > P. nameko > A. aegirit > A. auricula > B. edulis > T. matsutake.

Emerging insights into the impacts of heavy metals exposure on health, reproductive and productive performance of livestock

Heavy metals, common environmental pollutants with widespread distribution hazards and several health problems linked to them are distinguished from other toxic compounds by their bioaccumulation in living organisms. They pollute the food chain and threaten the health of animals. Biologically, heavy metals exhibit both beneficial and harmful effects. Certain essential heavy metals such as Co, Mn, Se, Zn, and Mg play crucial roles in vital physiological processes in trace amounts, while others like As, Pb, Hg, Cd, and Cu are widely recognized for their toxic properties. Regardless of their physiological functions, an excess intake of all heavy metals beyond the tolerance limit can lead to toxicity. Animals face exposure to heavy metals through contaminated feed and water, primarily as a result of anthropogenic environmental pollution. After ingestion heavy metals persist in the body for an extended duration and the nature of exposure dictates whether they induce acute or chronic, clinical or subclinical, or subtle toxicities. The toxic effects of metals lead to disruption of cellular homeostasis through the generation of free radicals that develop oxidative stress. In cases of acute heavy metal poisoning, characteristic clinical symptoms may arise, potentially culminating in the death of animals with corresponding necropsy findings. Chronic toxicities manifest as a decline in overall body condition scoring and a decrease in the production potential of animals. Elevated heavy metal levels in consumable animal products raise public health concerns. Timely diagnosis, targeted antidotes, and management strategies can significantly mitigate heavy metal impact on livestock health, productivity, and reproductive performance.

Melatonin as a Repairing Agent in Cadmium- and Free Fatty Acid-Induced Lipotoxicity

(1) Background: Cadmium (Cd) is a potentially toxic element with a long half-life in the human body (20-40 years). Cytotoxicity mechanisms of Cd include increased levels of oxidative stress and apoptotic signaling, and recent studies have suggested that these aspects of Cd toxicity contribute a role in the pathobiology of non-alcoholic fatty liver disease (NAFLD), a highly prevalent ailment associated with hepatic lipotoxicity and an increased generation of reactive oxygen species (ROS). In this study, Cd toxicity and its interplay with fatty acid (FA)-induced lipotoxicity have been studied in intestinal epithelium and liver cells; the cytoprotective function of melatonin (MLT) has been also evaluated. (2) Methods: human liver cells (HepaRG), primary murine hepatocytes and Caco-2 intestinal epithelial cells were exposed to CdCl2 before and after induction of lipotoxicity with oleic acid (OA) and/or palmitic acid (PA), and in some experiments, FA was combined with MLT (50 nM) treatment. (3) Results: CdCl2 toxicity was associated with ROS induction and reduced cell viability in both the hepatic and intestinal cells. Cd and FA synergized to induce lipid droplet formation and ROS production; the latter was higher for PA compared to OA in liver cells, resulting in a higher reduction in cell viability, especially in HepaRG and primary hepatocytes, whereas CACO-2 cells showed higher resistance to Cd/PA-induced lipotoxicity compared to liver cells. MLT showed significant protection against Cd toxicity either considered alone or combined with FFA-induced lipotoxicity in primary liver cells. (4) Conclusions: Cd and PA combine their pro-oxidant activity to induce lipotoxicity in cellular populations of the gut-liver axis. MLT can be used to lessen the synergistic effect of Cd-PA on cellular ROS formation.

Cadmium cardiotoxicity is associated with oxidative stress and upregulated TLR-4/NF-kB pathway in rats; protective role of agomelatine

Cardiotoxicity is one of the hazardous effects of the exposure to the heavy metal cadmium (Cd). Inflammation and oxidative injury are implicated in the cardiotoxic mechanism of Cd. The melatonin receptor agonist agomelatine (AGM) showed promising effects against oxidative and inflammatory responses. This study evaluated the effect of AGM on Cd-induced cardiotoxicity in rats, pointing to its modulatory effect on TLR-4/NF-kB pathway and HSP70. Rats received AGM for 14 days and a single dose of Cd on day 7 and blood and heart samples were collected for analyses. Cd increased serum CK-MB, AST and LDH and caused cardiac tissue injury. Cardiac malondialdehyde (MDA), nitric oxide (NO) and MPO were elevated and GSH, SOD and GST decreased in Cd-administered rats. AGM ameliorated serum CK-MB, AST and LDH and cardiac MDA, NO and MPO, prevented tissue injury and enhanced antioxidants. AGM downregulated serum CRP and cardiac TLR-4, NF-kB, iNOS, IL-6, TNF-α and COX-2 in Cd-administered rats. HSP70 was upregulated in the heart of Cd-challenged rats treated with AGM. In silico findings revealed the binding affinity of AGM with TLR-4 and NF-kB. In conclusion, AGM protected against Cd cardiotoxicity by preventing myocardial injury and oxidative stress and modulating HSP70 and TLR-4/NF-kB pathway.

Sperm Rhoa m6A modification mediates intergenerational transmission of paternally acquired hippocampal neuronal senescence and cognitive deficits after combined exposure to environmental cadmium and high-fat diet in mice

Little is currently known about the effect and mechanism of combined paternal environmental cadmium (Cd) and high-fat diet (HFD) on offspring cognitive ability. Here, using in vivo model, we found that combined paternal environmental Cd and HFD caused hippocampal neuronal senescence and cognitive deficits in offspring. MeRIP-seq revealed m6A level of Rhoa, a regulatory gene of cellular senescence, was significantly increased in combined environmental Cd and HFD-treated paternal sperm. Interestingly, combined paternal environmental Cd and HFD markedly enhanced Rhoa mRNA, its m6A and reader protein IGF2BP1 in offspring hippocampus. STM2457, the inhibitor of m6A modification, markedly mitigated paternal exposure-caused the elevation of hippocampal Rhoa m6A, neuronal senescence and cognitive deficits in offspring. In vitro experiments, Rhoa siR significantly reversed mouse hippocampal neuronal senescence. Igf2bp1 siR obviously reduced the level and stability of Rhoa in aging mouse hippocampal neuronal cells. In conclusion, combined paternal environmental Cd and HFD induce offspring hippocampal neuronal senescence and cognitive deficits by promoting IGF2BP1-mediated Rhoa stabilization in offspring hippocampus via elevating Rhoa m6A in paternal sperm.

Delineating the protective action of cordycepin against cadmium induced oxidative stress and gut inflammation through downregulation of NF-κB pathway

Cadmium (Cd) exposure is known to cause gut inflammation. In this study, we investigated the protective effects of cordycepin, a natural compound with pharmacological properties, against gut inflammation induced by Cd exposure. Using zebrafish larvae and colon cell line models, we examined the impact of cordycepin on Cd-induced toxicity and inflammation. Zebrafish larvae were exposed to Cd (2 µg/mL) and treated with different concentrations of cordycepin (12.5, 25 and 50 µg/mL). Cordycepin treatment significantly reduced Cd-induced embryotoxicity in zebrafish larvae. It also alleviated Cd-induced oxidative stress by reducing reactive oxygen species (ROS), lipid peroxidation and apoptosis. Furthermore, cordycepin treatment normalized the levels of liver-related biomarkers affected due to Cd exposure. Additionally, cordycepin (50 µg/mL) demonstrated a significant reduction in Cd bioaccumulation and downregulated the expression of inflammatory genes in both zebrafish larval gut and colon cell lines. These findings suggest that cordycepin could be an effective agent against Cd-induced gut inflammation.

Acetovanillone augmented the cardioprotective effect of carvedilol against cadmium-induced heart injury via suppression of oxidative stress and inflammation signaling pathways

Cardiac toxicity is a public health issue that can be caused by both environmental and occupational exposures. The current study aimed to investigate the effectiveness of carvedilol (CV), Acetovanillone (ACET), and their combination for ameliorating cadmium (Cd)-induced oxidative stress, inflammation, and necroptosis. Rats were assigned to; the normal group, Cd group (2 mg/kg; i.p., single dose), and the other three groups received orally CV (10 mg/kg), ACET (25 mg/kg), and CV plus ACET, respectively and a single dose of Cd. Oral administration of CV, ACET, and their combination significantly dampens cardiac oxidative injury by increasing antioxidants GSH and SOD levels, while it decreases MDA and NADPH oxidase levels mediated by decreasing cardiac abundance of Nrf2, HO-1, and SIRT1 and downregulating KEAP-1 and FOXO-3 levels. Also, they significantly attenuated inflammatory response as indicated by reducing MPO and NOx as well as proinflammatory cytokines TNF-α and IL-6 mediated by downregulating TLR4, iNOS, and NF-κB proteins expression as well as IκB upregulation. Moreover, they potently counteracted cardiac necroptosis by downregulating RIPK1, RIPK3, MLKL, and caspase-8 proteins expression. Of note, the combination of CV and ACET have marked protection that exceeded each drug alone. Conclusively, CV ad ACET potently mitigated Cd-induced cardiac intoxication by regulating NADPH oxidase, KEAP-1/Nrf2/HO-1, SIRT1/FOXO-3, TLR4/NF-κB/iNOS, and RIPK1/RIPK3/MLKL signals.

Does maternal low-dose cadmium exposure increase the risk of offspring to develop metabolic syndrome and/or type 2 diabetes?

Cadmium is a hazardous metal with multiple organ toxicity that causes great harm to human health. Cadmium enters the human body through occupational exposure, diet, drinking water, breathing, and smoking. Cadmium accumulation in the human body is associated with increased risk of developing obesity, cardiovascular disease, diabetes, and metabolic syndrome (MetS). Cadmium uptake is enhanced during pregnancy and can cross the placenta affecting placental development and function. Subsequently, cadmium can pass to fetus, gathering in multiple organs such as the liver and pancreas. Early-life cadmium exposure can induce hepatic oxidative stress and pancreatic β-cell dysfunction, resulting in insulin resistance and glucose metabolic dyshomeostasis in the offspring. Prenatal exposure to cadmium is also associated with increasing epigenetic effects on the offspring's multi-organ functions. However, whether and how maternal exposure to low-dose cadmium impacts the risks of developing type 2 diabetes (T2D) in the young and/or adult offspring remains unclear. This review collected available data to address the current evidence for the potential role of cadmium exposure, leading to insulin resistance and the development of T2D in offspring. However, this review reveals that underlying mechanisms linking prenatal cadmium exposure during pregnancy with T2D in offspring remain to be adequately investigated.

Correlative study on heavy metal-induced oxidative stress and hypertension among the rural population of Malwa Region of Punjab, India

Heavy metal-induced toxicity contributes to the progression of various metabolic disorders and possible mechanisms involved in disease progression are not well established. In this study, the correlation of  heavy metal exposure and  hypertension have been demonstrated. The results showed that in hypertensive subjects, the lipid profiles (triglycerides, LDL-C, HDL-C, and total cholesterol) and cardiac markers (CK-MB and LDH) were altered abruptly. As a consequence of heavy- induced oxidative stress, the oxidants (TBARS and protein carbonyls) and antioxidants (SOD, GSH, and TAC) were significantly increased and decreased, respectively in hypertension subjects. The concentrations of heavy metals (Pb, Cd, and As) exceeded the permissible limits in hypertensive subjects. The Nrf-2 genotyping indicated that heavy metals may induce mutations at molecular level. The results of correlation analysis revealed that the heavy metals interact with cellular components and interfere with metabolic processes which then results in disturbed lipid profile, enhanced oxidative stress, and reduced antioxidant status. The current study systematically estimated the association of hair and nail heavy metal concentrations with hypertension among the population residing in the Malwa region of Punjab. The proposed study highlighted that heavy metals act as a silent risk factor in the hypertension progression in the population of Malwa region. Future studies are required to confirm current findings and further scrutinize the effect of heavy metals exposure in early adulthood, early, and late mid-life to develop metabolic complications such as hypertension.

A systematic review of adverse health effects associated with oral cadmium exposure

Scientific data characterizing the adverse health effects associated with dietary cadmium (Cd) exposure were identified in order to make informed decisions about the most appropriate toxicological reference value (TRV) for use in assessing dietary Cd exposure. Several TRVs are available for Cd and regulatory organizations have used epidemiologic studies to derive these reference values; however, risk of bias (RoB) evaluations were not included in the assessments. We performed a systematic review by conducting a thorough literature search (through January 4, 2020). There were 1714 references identified by the search strings and 328 studies identified in regulatory assessments. After applying the specific inclusion and exclusion criteria, 208 studies (Human: 105, Animal: 103) were considered eligible for further review and data extraction. For the epidemiologic and animal studies, the critical effects identified for oral Cd exposure from the eligible studies were a decrease in bone mineral density (BMD) and renal tubular degeneration. A RoB analysis was completed for 49 studies (30 epidemiological and 19 animal) investigating these endpoints. The studies identified through the SR that were considered high quality and low RoB (2 human and 5 animal) can be used to characterize dose-response relationships and inform the derivation of a Cd TRV.

Gallic and ascorbic acids supplementation alleviate cognitive deficits and neuropathological damage exerted by cadmium chloride in Wistar rats

Cadmium is a highly neurotoxic heavy metal that interferes with DNA repair mechanisms via generation of reactive oxygen species. The potentials of polyphenols and antioxidants as effective protective agents following heavy metal-induced neurotoxicity are emerging. We therefore explored the neuroprotective potentials of gallic and ascorbic acids in CdCl₂-induced neurotoxicity. Seventy-two Wistar rats were divided into six groups. Group A received distilled water, B: 3 mg/kg CdCl₂, C: 3 mg/kg CdCl₂ + 20 mg/kg gallic acid (GA), D: 3 mg/kg CdCl₂ + 10 mg/kg ascorbic acid (AA), E: 20 mg/kg GA and F: 10 mg/kg AA orally for 21 days. Depression, anxiety, locomotion, learning and memory were assessed using a battery of tests. Neuronal structure and myelin expression were assessed with histological staining and immunofluorescence. The Morris Water Maze test revealed significant increase in escape latency in CdCl₂ group relative to rats concurrently treated with GA or AA. Similarly, time spent in the target quadrant was reduced significantly in CdCl₂ group relative to other groups. Concomitant administration of gallic acid led to significant reduction in the durations of immobility and freezing that were elevated in CdCl₂ group during forced swim and open field tests respectively. Furthermore, GA and AA restored myelin integrity and neuronal loss observed in the CdCl₂ group. We conclude that gallic and ascorbic acids enhance learning and memory, decrease anxiety and depressive-like behavior in CdCl₂-induced neurotoxicity with accompanying myelin-protective ability.

Mice lacking α4 nicotinic acetylcholine receptors are protected against alcohol-associated liver injury

BACKGROUND

Chronic heavy alcohol consumption is a major risk factor for the development of liver steatosis, fibrosis, and cirrhosis, but the mechanisms by which alcohol causes liver damage remain incompletely elucidated. This group has reported that α4 nicotinic acetylcholine receptors (α4 nAChRs) act as sensors for alcohol in lung cells. This study tested the hypothesis that α4 nAChRs mediate the effects of alcohol in the liver.

METHODS

Expression of acetylcholine receptor subunits in mouse liver was determined by RNA sequencing (RNA-seq). α4 nAChR knockout (α4 KO) mice were generated in C57BL/6J mice by introducing a mutation encoding an early stop codon in exon 4 of Chrna4, the gene encoding the α4 subunit of the nAChR. The presence of the inactivating mutation was established by polymerase chain reaction and genomic sequencing, and the lack of α4 nAChR function was confirmed in primary fibroblasts isolated from the α4 KO mice. Wild-type (WT) and α4 KO mice were fed the Lieber-DeCarli diet (with 36% of calories from alcohol) or pair fed an isocaloric maltose-dextrin control diet for a 6-week period that included a ramping up phase of increasing dietary alcohol.

RESULTS

Chrna4 was the most abundantly expressed nAChR subunit gene in mouse livers. After 6 weeks of alcohol exposure, WT mice had elevated serum transaminases and their livers showed increased fat accumulation, decreased Sirt1 protein levels, and accumulation of markers of oxidative stress and inflammation including Cyp2E1, Nos2, Sod1, Slc7a11, TNFα, and PAI1. All these responses to alcohol were either absent or significantly attenuated in α4 KO animals.

CONCLUSION

Together, these observations support the conclusion that activation of α4 nAChRs by alcohol or one of its metabolites is one of the initial events promoting the accumulation of excess fat and expression of inflammatory mediators. Thus, α4 nAChRs may represent viable targets for intervention in chronic alcohol-related liver disease.

Dietary cadmium induced declined locomotory and reproductive fitness with altered homeostasis of essential elements in Drosophila melanogaster

Cadmium (Cd) exerts detrimental effects on multiple biological processes of the living organisms along with epigenetic transgenerational effect. Drosophila melanogaster offers unique opportunity to evaluate Cd toxicity when studying important life traits in short duration of time by designing distinct behavioural assays. Present study utilized this model organism to assess Cd induced lethality, retarded growth, decreased life span and altered behaviour of the animals either at larval or adult stage. Our investigations revealed reduced locomotion and reproductive fitness of the animals upon Cd exposure. Transgenerational effect on locomotion was found to be behaviour specific as larval crawling was affected, but adult fly negative geotaxis was comparable to the control. Mechanistically, decreased antioxidant enzymes activity, superoxide dismutase (SOD) and catalase (CAT) together with altered homeostasis of essential elements (Fe, Zn and Mg) may be responsible for the observed effects. Altogether our work showed extensive range of Cd altered Drosophila behaviour which warrants need to control environmental Cd toxicity.

Exposure to low-dose cadmium induces testicular ferroptosis

As an environmental pollutant, cadmium (Cd) has been widely reported to induce male infertility due to its gonadotoxicity. However, the specific mechanism of Cd-induced testicular damage remains unclear. We investigated whether Cd causes testicular injury through ferroptosis. Male C57BL/6 J mice were exposed to 0, 0.5, or 5 ppm Cd via drinking water, starting in utero, and continuing through 24 weeks post-weaning. The results showed that Cd accumulated in the testes in a dose-dependent manner. Cd exposure at a concentration of 5 ppm, but not 0.5 ppm, caused a mass loss and detachment of germ cells, as well as a decreased meiotic index and testis weight. Exposure to 5 ppm Cd caused iron accumulation, increased levels of malondialdehyde (MDA) and nitro tyrosine (3-NT), and decreased expression of Nrf2, HO-1 and SOD2. We also found that exposure to 5 ppm Cd significantly decreased the expression of SLC7A11, a marker of ferroptosis in mice, along with the expression of SLC40A1 mRNA and ferritin heavy chain (FTH) protein, whereas there was no obvious change in the mRNA expression of Tfrc, ZIP8, ZIP14, and NCOA4. These findings indicate that 5 ppm Cd exposure increased testicular ferroptosis, which may be attributed to the reduction of stored iron export.

Sex differences in the effects of whole-life, low-dose cadmium exposure on postweaning high-fat diet-induced cardiac pathogeneses

We previously showed the development of cardiac remodeling (hypertrophy or fibrosis) in mice with either post-weaning high-fat diet (HFD, 60% kcal fat) feeding or exposure to chronic low-dose cadmium. Here, we determined whether whole-life exposure to environmentally relevant, low-dose cadmium affects the susceptibility of offspring to post-weaning HFD-induced cardiac pathologies and function. Besides, we also determined whether these effects are sex-dependent. Male and female mice were exposed to cadmium-containing (0, 0.5, or 5 parts per million [ppm]) drinking water before breeding; the pregnant mice and dams with offspring continually drank the same cadmium-containing water. After weaning, the offspring were continued on the same regime as their parents and fed either a HFD or normal fat diet for 24 weeks. Cardiac function was examined with echocardiography. Cardiac tissues were used for the histopathological and biochemical (gene and protein expression by real-time PCR and Western blotting) assays. Results showed a dose-dependent cadmium accumulation in the hearts of male and female mice along with decreased cardiac zinc and copper levels only in female offspring. Exposure to 5 ppm, but not 0.5 ppm, cadmium significantly enhanced HFD cardiac effects only in female mice, shown by worsened cardiac systolic and diastolic dysfunction (ejection fraction, mitral E-to-annular e' ratio), increased fibrosis (collagen, fibronectin, collagen1A1), hypertrophy (cardiomyocyte size, atrial natriuretic peptide, β-myosin heavy chain), and inflammation (intercellular adhesion molecule-1, tumor necrosis factor-α, plasminogen activator inhibitor type 1), compared to the HFD group. These synergistic effects were associated with activation of the p38 mitogen-activated protein kinases (MAPK) signaling pathway and increased oxidative stress, shown by 3-nitrotyrosine and malondialdehyde, along with decreased metallothionein expression. These results suggest that whole-life 5 ppm cadmium exposure significantly increases the susceptibility of female offspring to HFD-induced cardiac remodeling and dysfunction. The underlying mechanism and potential intervention will be further explored in the future.

Whole life exposure to low dose cadmium alters diet-induced NAFLD

Nonalcoholic fatty liver disease (NAFLD) is a major global public health concern affecting more than 25% of the world's population. Although obesity and diabetes are major risk factors for NAFLD, they cannot account for all cases, indicating the importance of other factors such as environmental exposures. Cadmium (Cd) exposure is implicated in the development of NAFLD; however, the influence of early life, in utero Cd exposure on the development of diet-induced NAFLD is poorly understood. Therefore, we developed an in vivo, multiple-hit model to study the effect of whole-life, low dose Cd exposure on high fat diet (HFD)-induced NAFLD. Adult male and female C57BL/6 J mice fed normal diets (ND) were exposed to 0, 0.5 or 5 ppm Cd-containing drinking water for 14 weeks before breeding. At weaning, offspring were fed ND or HFD and continued on the same drinking water regimen as their parents for 24 weeks. Cd exposure at different concentrations differentially altered HFD-associated adverse health effects, including liver injury. HFD-induced increased body weight, decreased glucose tolerance. Liver injury and lipid deposition were exacerbated by 5 ppm Cd exposure but attenuated by 0.5 ppm Cd exposure. Further, HFD blunted the response of metallothionein, a major Cd detoxification protein, in mice exposed to 5 ppm Cd but enhanced the response in mice exposed to 0.5 ppm Cd, suggesting a possible mechanism for Cd alteration of HFD-induced NAFLD. These results confirm the multi-hit nature of NAFLD and show whole life, low dose Cd exposure alters HFD-induced NAFLD with outcomes dependent on Cd concentration.

Effects of whole-life exposure to low-dose cadmium with post-weaning high-fat diet on offspring testes in a male mouse model

Although several studies have reported testicular impairments caused by cadmium (Cd) or obesity alone, the combined effect of Cd and obesity on the testes and its underlying mechanism remains unclear. We examined the combined effect of whole-life exposure to low-dose Cd started at preconception and post-weaning high-fat diet (HFD) on the testes of offspring mice. At weaning, male offspring parented with and without exposure to low-dose Cd were continued on the same drinking water regimen as their parents and fed with either a normal diet (ND) or HFD for 10 or 24 weeks. Whole-life exposure to Cd resulted in its accumulation in testes, and HFD induced obesity and lipid metabolism disorder. Exposure to Cd or HFD alone significantly decreased Johnsen scores, disrupted testicular structure, and increased germ cell apoptosis at both 10 and 24 weeks. However, co-exposure to Cd and HFD did not induce the toxic effects that were induced by either alone, as revealed by preserved testicular structure and spermatogenesis, lack of significant apoptosis, and increased cell proliferation. Mechanistically, the combined effects of low-dose Cd and HFD consumption were associated with the activation of the JAK/STAT pathway. These findings suggest that co-exposure to low-dose Cd and HFD did not cause Cd- or HFD-induced testicular injury, probably because of the activation of the JAK/STAT pathway to prevent germ cell apoptosis.

Evaluation of Contamination Status and Health Risk Assessment of Essential and Toxic Metals in Cyprinus carpio from Mangla Lake, Pakistan

Although fish as a diet has many health benefits, metal accumulation in fish has been an increasing public health concerns across the world. The Cyprinus carpio samples were collected from Mangla Lake, Mirpur, Azad Kashmir, Pakistan, and analyzed for 18 essential and toxic trace metals. In edible muscles of the fish, average concentration (μg/g) of K (3002) was the highest, followed by Na (648), Ca (435), Mg (227), and Zn (161). Relatively lower levels (μg/g) were noted for Fe (16.9), Pb (6.05), Sr (4.01), Se (3.49), Co (2.90), Ni (2.37), Mn (2.29), As (1.48), and Cu (1.37), while least levels (μg/g) were found for Cr (0.61), Cd (0.52), Hg (0.15), and Li (0.09) in muscles. Majority of the metals revealed higher accumulation in gills compared with those in scales and muscles. Mean levels of Zn, Mn, Co, Pb, As, and Cd in Cyprinus carpio muscles were found to be exceeding most of the international permissible limits in muscles for safe human consumption. Estimated daily/weekly intakes and hazard quotients/index suggested a high risk related to the intake of Cyprinus carpio from Mangla Lake due to heavy metal contamination. Likewise, target cancer risk (TCR) also indicated significant lifetime carcinogenic health risks to the consumers.

Chronic Cadmium Exposure Alters Cardiac Matrix Metalloproteinases in the Heart of Sprague-Dawley Rat

The aim of this study was to evaluate the role of chronic cadmium exposure in modulating cardiac matrix metalloproteinases (MMPs) in the heart of rats. Adult male Sprague-Dawley rats were exposed to 15 ppm CdCl₂ in drinking water for 10 weeks followed by withdrawal of cadmium treatment for 4 weeks. Following the completion of the treatment, gene expression of inflammatory mediators (IL-1β, IL-6, IL-10, TNF-α and NF-κB), protein expression of MMP-2, MMP-9 and their respective inhibitors- TIMP-1 and TIMP-2, and gelatinolytic activity of MMP-2 and MMP-9 were determined. At the protein level, cadmium incites a differential effect on the expression and activity of gelatinases and their endogenous inhibitors in an exposure-dependent manner. Results also show that the administered cadmium dose elicits an inflammatory response until week 10 that slightly diminishes after 4 weeks. This study provides evidence of cadmium-induced imbalance in the MMP-TIMP system in the cardiac tissue. This imbalance may be mediated by cadmium-induced inflammation that could contribute to various cardiovascular pathologies.

Cadmium Accumulation and Depuration in the Muscle of Prussian Carp (Carassius gibelio Bloch) after Sub-Chronic Cadmium Exposure: Ameliorating Effect of Melatonin

Simple Summary

Rapid urbanization and industrialization has resulted in substantial contamination of various ecosystems, especially aquatic environments with heavy metals. Heavy metals are classified as either essential (iron, zinc, or copper) or non-essential (cadmium, lead, or mercury) for organisms. Cadmium is a toxic, cancerogenic, and mutagenic metal, occurring as anthropogenic contamination in aquatic environments. The level of cadmium uptake in animals depends on the rate at which they are accumulated and eliminated. Exceeding the permissible levels of cadmium in fish muscle may pose risks for human health in the case of contaminated fish consumption. The aim of the present study was to evaluate the influence of melatonin on cadmium accumulation and elimination in fish muscle. Prussian carps were exposed to two doses of cadmium in the presence or without the melatonin implants. This is the first study to report that melatonin co-administration can effectively protect fish from the accumulation of cadmium in muscle tissue, improve the accumulated cadmium depuration from muscle, and prevent disturbance of the concentration of essential metals in fish body.

Abstract

The aim of this study was to investigate the bioaccumulation of cadmium in the muscle tissue of Prussian carp during 7 and 13 weeks of exposure to different concentrations of this metal in water (0.4 and 4.0 mg/L), and the depuration of cadmium from muscle during the following 6-week depuration period in the presence of melatonin implants. Furthermore, the relationship between cadmium accumulation and the levels of essential bioelements (copper, zinc, iron) in muscle was evaluated, as well as the bioconcentration factor of cadmium. Heavy metal concentration was determined using atomic absorption spectrometry. Cadmium accumulation in fish muscle increased with the duration of exposure. Cd concentrations exceeded the permissible levels for human consumption in groups exposed to the higher concentration of this metal. Moreover, a significant increase of Zn and Fe levels in the muscle was observed. In the fish that received melatonin implants and were exposed to Cd, its level in the muscle was significantly lower. The depuration of accumulated cadmium depended mainly on the duration of the elimination period. This is the first study to report that melatonin co-administration can effectively protect the fish from the accumulation of cadmium in muscle tissue and changes in trace metal levels.

Gestational Cd Exposure in the CD-1 Mouse Induces Sex-Specific Hepatic Insulin Insensitivity, Obesity, and Metabolic Syndrome in Adult Female Offspring

There is compelling evidence that developmental exposure to toxic metals increases risk for obesity and obesity-related morbidity including cardiovascular disease and type 2 diabetes. To explore the hypothesis that developmental Cd exposure increases risk of obesity later in life, male, and female CD-1 mice were maternally exposed to 500 ppb CdCl2 in drinking water during a human gestational equivalent period (gestational day 0-postnatal day 10 [GD0-PND10]). Hallmark indicators of metabolic disruption, hepatic steatosis, and metabolic syndrome were evaluated prior to birth through adulthood. Maternal blood Cd levels were similar to those observed in human pregnancy cohorts, and Cd was undetected in adult offspring. There were no observed impacts of exposure on dams or pregnancy-related outcomes. Results of glucose and insulin tolerance testing revealed that Cd exposure impaired offspring glucose homeostasis on PND42. Exposure-related increases in circulating triglycerides and hepatic steatosis were apparent only in females. By PND120, Cd-exposed females were 30% heavier with 700% more perigonadal fat than unexposed control females. There was no evidence of dyslipidemia, steatosis, increased weight gain, nor increased adiposity in Cd-exposed male offspring. Hepatic transcriptome analysis on PND1, PND21, and PND42 revealed evidence for female-specific increases in oxidative stress and mitochondrial dysfunction with significant early disruption of retinoic acid signaling and altered insulin receptor signaling consistent with hepatic insulin sensitivity in adult females. The observed steatosis and metabolic syndrome-like phenotypes resulting from exposure to 500 ppb CdCl2 during the pre- and perinatal period of development equivalent to human gestation indicate that Cd acts developmentally as a sex-specific delayed obesogen.

Role of Autophagy in Cadmium-Induced Hepatotoxicity and Liver Diseases

Cadmium (Cd) is a toxic pollutant that is associated with several severe human diseases. Cd can be easily absorbed in significant quantities from air contamination/industrial pollution, cigarette smoke, food, and water and primarily affects the liver, kidney, and lungs. Toxic effects of Cd include hepatotoxicity, nephrotoxicity, pulmonary toxicity, and the development of various human cancers. Cd is also involved in the development and progression of fatty liver diseases and hepatocellular carcinoma. Cd affects liver function via modulation of cell survival/proliferation, differentiation, and apoptosis. Moreover, Cd dysregulates hepatic autophagy, an endogenous catabolic process that detoxifies damaged cell organelles or dysfunctional cytosolic proteins through vacuole-mediated sequestration and lysosomal degradation. In this article, we review recent developments and findings regarding the role of Cd in the modulation of hepatotoxicity, autophagic function, and liver diseases at the molecular level.

Effects of cadmium and high-fat diet on essential metal concentration in the mouse testis

The effects of exposure to the environmental toxicant cadmium, in combination with obesity, on the metal content in mouse testis were evaluated. Starting in utero and continuing through to 10 or 24 weeks post-weaning, male mice were exposed to cadmium (0, 0.5 or 5 ppm), and fed either a low (LFD) or high fat diet (HFD) post-weaning. Testicular levels of cadmium and essential metals were determined 10 and 24 weeks post-weaning by ICP-MS. Similar to what has been previously observed in the liver, kidney, heart and brain, significant levels of cadmium accumulated in the testis under all exposure conditions. Additionally, HFD-fed animals accumulated more cadmium than did their LFD-treated counterparts. Both treatments affected essential metal homeostasis in the testis. These findings suggest that cadmium and obesity may compromise the reproductive potential in the male mouse by disrupting essential metal levels.

Disruption of essential metal homeostasis in the brain by cadmium and high-fat diet

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Whole-life exposure to cadmium leads to elevated metal levels in the brain that further increases in high-fat diet fed mice.

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Female animals accumulate more cadmium in the brain than males, under all treatment conditions.

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Cadmium exposure is associated with changes in the levels of several essential metals.

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Cadmium and high fat diet increase levels of superoxide anion in the cortex, amygdala and hippocampus.

Analyses of human cohort data support the roles of cadmium and obesity in the development of several neurocognitive disorders. To explore the effects of cadmium exposure in the brain, mice were subjected to whole life oral cadmium exposure. There were significant increases in cadmium levels with female animals accumulating more metal than males (p < 0.001). Both genders fed a high fat diet showed significant increases in cadmium levels compared to low fat diet fed mice (p < 0.001). Cadmium and high fat diet significantly affected the levels of several essential metals, including magnesium, potassium, chromium, iron, cobalt, copper, zinc and selenium. Additionally, these treatments resulted in increased superoxide levels within the cortex, amygdala and hippocampus. These findings support a model where cadmium and high fat diet affect the levels of redox-active, essential metal homeostasis. This phenomenon may contribute to the underlying mechanism(s) responsible for the development of neurocognitive disorders.

Assessment of potential human health risk of trace element in wild edible mushroom species collected from Yunnan Province, China

Wild edible mushrooms are rich in nutritions and popular among people, but wild edible mushrooms easily accumulate potentially harmful trace elements, and excessive intake will harm health. The aim of this study was to investigate the potential health hazards of long-term intake of wild edible mushrooms in Yunnan Province, China. The concentrations of trace element (As, Cd, Cr, Cu, Hg, Pb, Ni, and Zn) in 19 species of wild edible mushrooms in Yunnan Province were determined by inductively coupled plasma mass spectrometry (ICP-MS). Further processing of the data, the potential health risk assessments of consumers were evaluated by the target hazard quotient (THQ), hazard index (HI), and incremental lifetime cancer risk (ILCR), respectively. Results showed that concentrations of trace element in wild edible mushrooms decreased in the order of Zn > Cu > As > Ni > Cr > Cd > Pb > Hg. Compared with the maximum standard by the WHO/China, the averages of As, Cd, Cr, Hg, and Zn were significantly greater than the standard. Among the tested wild edible mushrooms, HI values of Leccinum crocipodium, Thelephora ganbajun, Lactarius luteolus, Tricholoma matsutake, and Polyporus ellisii were more than 1. Thus, Leccinum crocipodium, Thelephora ganbajun, Lactarius luteolus, Tricholoma matsutake, and Polyporus ellisii are the main sources of risk. The value of THQ in ascending order was as follows: Pb (0.11) < Cd (0.75) < As (4.27) < Hg (6.87). Thus, Hg are the primary sources of health risk in the wild edible mushrooms in Yunnan Province. ILCR_(As) values of Thelephora ganbajun, Tricholoma matsutake, Laccaria amethystea, and Polyporus ellisii were more than 10^-4, these four samples are the primary sources of health risk. The mean values of ILCR for As in wild mushroom were 1.01 × 10^-4. The results suggest that there was potential health risk to the consumer associated with the long-term consumption of wild edible mushrooms collected from Yunnan Province. We propose that the concentrations of trace element should be periodically monitored in wild edible mushrooms.

Implications for prenatal cadmium exposure and adverse health outcomes in adulthood

Cadmium is a ubiquitous, non-essential metal that has earned a spot on the World Health Organizations top 10 chemicals of major public health concern. The mechanisms of cadmium-induced adverse health outcomes, such as cardiovascular disease, renal toxicity and cancer, are well studied in adults. However, the implications for early life exposures to low-level cadmium leading to increased risk of developing diseases in adulthood remains elusive. Epidemiological investigation of the long term implications of cadmium-associated adverse birth outcomes are limited and studies do not extend into adulthood. This review will summarize the literature on the non-lethal, adverse health effects associated with prenatal and early life exposure to cadmium and the implications of these exposures in the development of diseases later in life. In addition, this review will highlight possible mechanisms responsible for these outcomes as well as address the inconsistencies in the literature. More recent studies have addressed sex as a biological variable, showing prenatal cadmium exposure elicits sex-specific outcomes that would otherwise be masked by pooling male and female data. Furthermore, researchers have begun to investigate the role of prenatal and early life cadmium exposures in the development of diet-induced diseases with evidence of altered essential metal homeostasis as a likely mechanism for cadmium-enhanced, diet-induced diseases. Although novel experimental models are beginning to be established to study the association between prenatal cadmium exposure and adverse health outcomes in adulthood, the studies are few, highlighting a major need for further investigation.

Reduced graphene oxide mitigates cadmium-induced cytotoxicity and oxidative stress in HepG2 cells

Numerous applications of reduced graphene oxide (RGO) and pervasive cadmium (Cd) have led concern about their co-exposure to the environment and human. We studied the combined effects of RGO and Cd in human liver (HepG2) cells. Initially, we found that RGO (up to 50 μg/ml) did not harm to HepG2 cells while Cd induced dose-dependent (1-10 μg/ml) cytotoxicity. Exciting observations were that a non-cytotoxic concentration of RGO (25 μg/ml) effectively mitigates the toxic effects of Cd (2 μg/ml) such as cell viability reduction, lactate dehydrogenase release, and irregular cell morphology. Cd-induced cell cycle arrest, induction of caspases (3 and 9) enzymes activity, and loss of mitochondrial membrane potential were also significantly alleviated by RGO co-exposure. Moreover, generation of pro-oxidants (reactive oxygen species and hydrogen peroxide levels) and depletion of antioxidants (glutathione level and superoxide dismutase activity) due to Cd exposure was effectively attenuated by RGO co-exposure. Mitigating effect of RGO could be due to strong adsorption of Cd on the large surface area of RGO sheets, which decrease the cellular uptake and bioavailability of Cd for HepG2 cells. This study warrants future research on potential mechanisms of mitigating effects of RGO against Cd-induced toxicity in animal models.

Blood BTEXS and heavy metal levels are associated with liver injury and systemic inflammation in Gulf states residents

INTRODUCTION

Exposures to volatile organic compounds and metals have previously been associated with liver diseases including steatohepatitis, although more data are needed. Benzene, toluene, ethylbenzene, xylenes, styrene (BTEXS) and metals were measured in blood samples collected between May 2012-July 2013 from volunteers participating in home visits for the Gulf Long-term Follow-up (GuLF) Study. This cross-sectional analysis evaluates associations of exposure biomarkers with serum liver injury and adipocytokine biomarkers in a sample of 214 men.

METHODS

Adult nonsmoking men without a history of liver disease or heavy alcohol consumption were included. The serologic disease biomarkers evaluated were the hepatocellular injury biomarker, cytokeratin 18 [whole (CK18 M65) and caspase-cleaved fragment (CK18 M30)]; and adipocytokines. Confounder-adjusted beta coefficients were determined using linear regression models for the overall sample (primary endpoints) and for obesity-classified sub-groups (secondary endpoints). A product interaction term between the exposure of interest and a dichotomized indicator of obesity was included to determine the disease modifying effects of obesity on the biomarker associations.

RESULTS

The study sample was 57% white and 51% obese. In the overall sample, lead was positively associated with CK18 M30 (β = 21.7 ± 6.0 (SE), p = 0.0004); IL-1β (β = 32.8 ± 5.2, p < 0.0001); IL-6 (β = 72.8 ± 18.3, p = 0.0001); and IL-8 (β = 140.8 ± 42.2, p = 0.001). Cadmium exposures were associated with increased IL-1β (β = 77.8 ± 26.3, p = 0.003) and IL-8 (β = 419.5 ± 201.2, p = 0.04). There were multiple significant interactions between obesity and exposure to lead, cadmium, benzene and toluene in relation to outcome biomarkers. Among obese participants (n = 108), benzene, lead, and cadmium were each positively associated with CK18 M30, IL-1β, IL-6, and IL-8. In obese subjects, lead was also inversely associated with leptin, and toluene was positively associated with IL-1β.

CONCLUSION

For the overall sample, heavy metal exposures were associated with liver injury (lead only) and/or systemic inflammation (lead and cadmium). Obesity modified the associations between BTEXS and heavy metal exposures on several of the outcome variables. In the obesity subgroup, liver injury was positively associated with lead, cadmium and benzene exposures; systemic inflammation was increased with lead, cadmium, benzene, and toluene exposures; and leptin was inversely associated with lead exposures. The cross-sectional design of this study makes it difficult to determine causality, and all results should be interpreted cautiously. Nonetheless, the potential impact of exposures to lead, cadmium, benzene and toluene in steatohepatitis, an obesity-associated inflammatory liver disease, warrants further investigation.