Synergic effects of 9,10-phenanthrenequinone and cadmium on pro-inflammatory responses in airway epithelial cells

We investigated the synergic effects of components of particulate matter with aerodynamic diameters ≤2.5μm (PM2.5) on airway inflammation. Co-exposure to cadmium (Cd) and 9,10-phenanthrenequinone (9,10-PQ) additively/synergistically increased pro-inflammatory responses in airway epithelial cells, whereas co-exposure to Cd and phenanthrene resulted in no acceleration. These results suggest that the combination of metal and a quinone derivative can contribute to the exacerbation of respiratory diseases by PM2.5.

Exploring the link between cadmium and psoriasis in a nationally representative sample

Psoriasis, a skin inflammatory disease, originates from dysregulated interactions of the immune system. Cadmium, an environment pollutant, increases the levels of inflammation markers and influences the immune system. To clarify the relationship between cadmium and psoriasis, 5,927 participants, ≥20 years, in the National Health and Nutrition Examination Survey (NHANES) 2003–2006 were studied. Psoriasis severity was assessed using self-reported dermatology questionnaires. Cadmium was measured using blood chemistry. Three adjusted models were applied for the interaction between serum cadmium and severity of psoriasis. Psoriasis patients had significantly higher blood cadmium (0.67 vs. 0.52 μg/L, p = 0.006). There was a strong linear increase in predicted blood cadmium values with an increase in severity of psoriasis (p for trend = 0.002). The β coefficient of the predicted serum cadmium in the “few patches to extensive psoriasis” group was 0.234 (p = 0.002) after adjusting covariates. Participants with severe psoriasis have higher blood cadmium. Environmental exposure to cadmium can predispose to the worsening of psoriasis. Although there are still limitations in this study, such as not included treatment data, these results have substantial public health implications for the general population, as they demonstrate the importance of cadmium exposure prevention, particularly among psoriasis patients.

Melatonin alleviates cadmium-induced liver injury by inhibiting the TXNIP-NLRP3 inflammasome

Cadmium (Cd) is a persistent environmental and occupational contaminant that accumulates in the liver and induces oxidative stress and inflammation. Melatonin possesses potent hepatoprotective properties against the development and progression of acute and chronic liver injury. Nevertheless, the molecular mechanism underlying the protective effects of melatonin against Cd-induced hepatotoxicity remains obscure. In this study, we aimed to investigate the effects of melatonin on Cd-induced liver inflammation and hepatocyte death. Male C57BL/6 mice were intraperitoneally injected with melatonin (10 mg/kg) once a day for 3 days before exposure to CdCl₂ (2.0 mg/kg). We found that Cd induced hepatocellular damage and inflammatory infiltration as well as increased serum ALT/AST enzymes. In addition, we showed that Cd triggered an inflammatory cell death, which is mediated by the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome. Moreover, melatonin treatment significantly alleviated Cd-induced liver injury by decreasing serum ALT/AST levels, suppressing pro-inflammatory cytokine production, inhibiting NLRP3 inflammasome activation, ameliorating oxidative stress, and attenuating hepatocyte death. Most importantly, melatonin markedly abrogated Cd-induced TXNIP overexpression and decreased the interaction between TXNIP and NLRP3 in vivo and in vitro. However, treatment with siRNA targeting TXNIP blocked the protective effects of melatonin in Cd-treated primary hepatocytes. Collectively, our results suggest that melatonin confers protection against Cd-induced liver inflammation and hepatocyte death via inhibition of the TXNIP-NLRP3 inflammasome pathway.

Protective effect of Fragaria ananassa methanolic extract on cadmium chloride (CdCl2)-induced hepatotoxicity in rats

This study investigated the protective effect of Fragaria ananassa methanolic extract on cadmium chloride (CdCl₂)-induced hepatotoxicity in rats. CdCl₂ was intraperitoneally injected at a dose of 6.5 mg/kg of body weight for 5 d with or without methanol extract of Fragaria ananassa (250 mg/kg). The hepatic cadmium concentration, lipid peroxidation, nitric oxide, glutathione (GSH) content, and antioxidant enzyme activities, including superoxide dismutase, catalase (CAT), GSH peroxidase, and GSH reductase, were estimated. CdCl₂ injection induced a significant elevation in cadmium concentration, lipid peroxidation, and nitric oxide and caused a significant depletion in GSH content compared to controls, along with a remarkable decrease in antioxidant enzymes. Oxidative stress induction and cadmium accumulation in the liver were successfully ameliorated by F. ananassa (strawberry) pre-administration. In addition, the pre-administration of strawberry decreased the elevated gene expression of the pro-apoptotic Bax gene as well as the protein expression of caspases-3 in the liver of CdCl₂-injected rats. In addition, the reduced gene expression of anti-apoptotic Bcl-2 was increased. Our results show an increase in the expression of tumor necrosis factor α in the liver of rats treated with cadmium. In sum, our results suggested that F. ananassa successfully prevented deleterious effects on liver function by reinforcing the antioxidant defense system, inhibiting oxidative stress and reducing apoptosis.

Cadmium exposure is associated with soluble urokinase plasminogen activator receptor, a circulating marker of inflammation and future cardiovascular disease

BACKGROUND

Diet and smoking are the main sources of cadmium exposure in the general population. Cadmium increases the risk of cardiovascular diseases, and experimental studies show that it induces inflammation. Blood cadmium levels are associated with macrophages in human atherosclerotic plaques. Soluble urokinase-type plasminogen activator receptor (suPAR) is an emerging biomarker for cardiovascular events related to inflammation and atherosclerotic plaques. The aim was to examine whether blood cadmium levels are associated with circulating suPAR and other markers of inflammation.

METHODS

A population sample of 4648 Swedish middle-aged women and men was examined cross-sectionally in 1991-1994. Plasma suPAR was assessed by ELISA, leukocytes were measured by standard methods, and blood cadmium was analysed by inductively coupled plasma mass spectrometry. Prevalent cardiovascular disease, ultrasound-assessed carotid plaque occurrence, and several possible confounding factors were recorded.

RESULTS

After full adjustment for risk factors and confounding variables, a 3-fold increase in blood cadmium was associated with an 10.9% increase in suPAR concentration (p<0.001). In never-smokers, a 3-fold increase in blood cadmium was associated with a 3.7% increase in suPAR concentration (p<0.01) after full adjustment. Blood cadmium was not associated with C-reactive protein, white blood cell count and Lp-PLA2 but with neutrophil/lymphocyte ratio in one of two statistical models.

CONCLUSIONS

Exposure to cadmium was associated with increased plasma suPAR in the general population, independently of smoking and cardiovascular disease. These results imply that cadmium is a possible cause for raised levels of this inflammatory marker.

Mitigation of cadmium-induced lung injury by Nigella sativa oil

Induction of oxidative stress and inflammation are considered the primary mechanism of cadmium (Cd) toxicity. Nigella sativa (NS) seeds and their oil (NSO) have been reported to possess antioxidant and anti-inflammatory potential. This study was conducted to assess the protective effect of NSO on Cd-induced lung damage in rat. Forty adult male Wistar rats were divided equally into 4 groups. Animals in groups I, II, and III received 1 ml of isotonic saline intraperitoneally (IP), 2 mg/kg of cadmium chloride (CdCl₂) dissolved in isotonic saline IP, and 1 ml/kg of NSO by gastric gavage, respectively. Group IV rats received NSO an hour prior to CdCl₂ administration via the same routes and doses as previously described. All animals were treated for 28 days. At the end of the study, animals were sacrificed; lungs were harvested for histopathological studies using light and electron microscopy. Saline-treated and NSO-treated rats showed normal lung parenchyma. However, CdCl₂-treated rats showed massive degenerative changes in alveolar epithelial lining, disrupted interalveolar septa, and hemolytic debris in alveoli. Rats treated with both NSO and CdCl₂ (group IV) showed amelioration of most Cd-induced lung damage with minimal histopathological changes in lung architecture. This study elucidates the protective effects of NSO on Cd-induced lung injury in rats and highlights the possibility of using NSO as a protective agent in individuals at high risk of Cd-induced lung toxicity.

Association of maternal serum cadmium level during pregnancy with risk of preterm birth in a Chinese population

Cadmium (Cd) was a developmental toxicant that induces fetal malformation and growth restriction in mice. However, epidemiological studies about the association of maternal serum Cd level with risk of preterm birth were limited. This study was to investigate whether maternal serum Cd level during pregnancy is associated with risk of preterm birth in a Chinese population. Total 3254 eligible mother-and-singleton-offspring pairs were recruited. Maternal serum Cd level was measured by GFAAS. Based on tertiles, maternal serum Cd concentration was classified as low (LCd, <0.65 μg/L), medium (MCd, 0.65-0.94 μg/L) and high (HCd, ≥0.95 μg/L). Odds ratio (OR) for preterm birth was estimated using multiple logistic regression models. Results showed the rate of preterm birth among LCd, M-Cd and HCd was 3.5%, 3.8%, and 9.4%, respectively. Subjects with HCd had a significantly higher risk for preterm birth (OR: 2.86; 95%CI: 1.95, 4.19; P < 0.001) than did those with LCd. Adjusted OR for preterm birth was 3.02 (95%CI: 2.02, 4.50; P < 0.001) among subjects with HCd compared to subjects with LCd. Taken together, the above results suggest that maternal serum Cd level during pregnancy is positively associated with risk of preterm birth.

Maternal urinary cadmium concentrations in relation to preterm birth in the Healthy Baby Cohort Study in China

BACKGROUND

Prenatal cadmium (Cd) exposure has been associated with adverse birth outcomes, but the findings of previous studies are inconsistent. The aim of this study was to evaluate the association between prenatal Cd exposure and birth outcomes.

METHODS

This study was conducted in 5364 pregnant women with a live singleton birth, who were recruited between September 2012 and October 2014 in the Healthy Baby Cohort (HBC) in Wuhan, China. Gestational age (in days) was estimated using both the woman's last menstrual period (LMP) and ultrasound data. All the birth outcomes including birth weight and birth length were measured in the hospital within one hour after birth through standardized procedures. Cd was measured in maternal urine collected before delivery with inductively coupled plasma mass spectrometry.

RESULTS

The geometric mean of Cd concentration in maternal urine was 0.55 (range 0.01-2.85) μg/g creatinine. We found each ln-unit increase in Cd concentration (μg/g creatinine) in maternal urine was associated with decreased gestational age [adjusted β=-0.77day; 95% confidence interval (CI): -1.15, -0.39 for all infants; -0.77; 95% CI: -1.29, -0.25 for boys; and -0.80; 95% CI: -1.35, -0.25 for girls]. Increased likelihood of preterm birth (PTB) was associated with ln-unit increase in urinary Cd (μg/g creatinine) [adjusted odds ratio (OR)=1.78; 95% CI: 1.45, 2.19 for all infants; 1.97; 95% CI: 1.46, 2.65 for boys; and 1.67; 95% CI: 1.24, 2.25 for girls]. Maternal urinary Cd was not significantly associated with low birth weight (LBW) and small for gestational age (SGA).

CONCLUSIONS

Maternal exposure to Cd during pregnancy was associated with decreased gestational age and increased likelihood of PTB.

Transcriptome profiling analysis of rare minnow (Gobiocypris rarus) gills after waterborne cadmium exposure

Rare minnow (Gobiocypris rarus) is a widely used experimental fish in risk assessments of aquatic pollutants in China. Cadmium (Cd) is one of the most toxic heavy metals in the world; however, few studies have used fish gills, a multi-functional organ. In this study, we characterized the differential expression of adult female rare minnow gills after sub-chronic waterborne Cd (75μg/L CdCl2) exposure for 35d. A total of 452 genes (209 up-regulated and 243 down-regulated) were identified by gene expression profiling using RNA-Seq before and after treatment. Of these differentially expressed genes, 75, 21, and 54 differentially expressed genes are related to ion transport, oxidation-reduction processes, and the immune response, respectively. The results of GO and KEGG enrichment analyses, together with the altered transcript levels of major histocompatibility complex (MHC) class I and class II molecules and the significant increases in the levels of serum tumor necrosis factor α (TNF-α), interleukin 1β (IL1β) and nuclear factor-κB (NF-κB), indicated a disruption of the immune system, particularly the induction of inflammation and autoimmunity. The significant down-regulation of coagulation factor XIII A1 polypeptide (F13A1), tripartite motif-containing protein 21 (TRIM21), and Golgi-associated plant pathogenesis-related protein (GAPr) during both acute (≤96h) and sub-chronic (35d) waterborne Cd exposure, as well as their dosage dependence, suggested that these three genes could be used as sensitive biomarkers for aquatic Cd risk assessment.

The Protective Effects of Melatonin Against Oxidative Stress and Inflammation Induced by Acute Cadmium Exposure in Mice Testis

Cadmium (Cd) is widely used in daily life and was recently recognized as a possible source of human toxicity due to its ability to accumulate in organs. Previous studies have shown that Cd exposure may cause testicular toxicity through oxidative stress and an inflammatory effect. Melatonin has been demonstrated to be an effective anti-oxidant and has an anti-inflammatory effect. The aim of the present study was to investigate the toxicological effects of Cd on reproduction in male mice and the potential protective action of melatonin against these adverse effects. Adult male mice were injected intraperitoneally with Cd at a dose of 2 mg/kg body weight per day for seven consecutive days with or without melatonin pretreatment. Sex organ weight, sperm parameters including sperm quality, apoptosis, acrosome integrity, mitochondrial membrane potential, testicular morphology, serum sex hormone, inflammatory status, and oxidative stress were evaluated. The results showed that significant adverse effects were observed in the male reproductive system after Cd exposure, including alterations in sperm parameters, increased DNA damage, and sex hormone disturbance. Acute Cd exposure also significantly increased malondialdehyde (MDA) contents, decreased glutathione (GSH) and superoxide dismutase (SOD) activities, and upregulated levels of the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), and interleukin-1beta (IL-1β), in the testis. In contrast, melatonin pretreatment significantly alleviated these toxic effects, and its mechanism may involve inhibiting MDA level, restoring GSH and SOD activities, and reducing the upregulation of TNF-α and IL-1β. Our data suggest that oxidative stress and inflammation are involved in Cd-induced toxicity in the male reproductive system and that co-administration of melatonin exerts a protective effect against Cd-induced male reproductive toxicity.

Cadmium exposure to murine macrophages decreases their inflammatory responses and increases their oxidative stress

Cadmium (Cd) is an environmental contaminant that poses serious risks to human and wildlife health. The oxidative stress and inflammatory responses induced by Cd were evaluated in RAW264.7 cells. A significant decrease in the cell viability was observed in the group treated with 3 µM Cd for 24 h. The mRNA levels of tumor necrosis factor-α (TNFα), interleukin-6 (IL6), interleukin-1α (IL1α) and Interleukin-1β (IL1β) were generally increased or decreased by Cd exposure for 6 and 24 h, respectively. Moreover, pretreatment of the RAW264.7 cells with Cd for 24 h inhibited the transcriptional status of TNFα, IL6, IL1α and IL1β and the release of these cytokines in response to a 6-h lipopolysaccharide (LPS) treatment in a dose-dependent manner. Furthermore, the Cd exposure elicited oxidative stress not only by disturbing the transcriptional status of genes including superoxide dismutase (Sod), catalase (Cat), glutathione peroxidase(Gpx), glutathione S-transferase 1 a (Gst1a),

NAD(P)H

quinone oxidoreductase 1(Nqo1), heme oxygenase 1(Ho-1) but also the enzyme activities of SOD, CAT and glutathione S-transferase (GST). The effects of Cd on the mRNA levels and activities of anti-oxidative enzymes were dependent on the exposure period and dose. These results suggested that Cd exposure generated oxidative stress and decreased the inflammatory responses in a murine macrophage cell line. Furthermore, oxidative stress may be a possible mechanism to explain the dysregulation of the immune function caused by heavy metals in this in vitro system.

Flavocoxid Protects Against Cadmium-Induced Disruption of the Blood–Testis Barrier and Improves Testicular Damage and Germ Cell Impairment in Mice [corrected]

Cadmium (Cd) causes male infertility. There is the need to identify safe treatments counteracting this toxicity. Flavocoxid is a flavonoid that induces a balanced inhibition of cyclooxygenase (COX)-1 and COX-2 peroxidase moieties and of 5-lipoxygenase (LOX) and has efficacy in the male genitourinary system. We investigated flavocoxid effects on Cd-induced testicular toxicity in mice. Swiss mice were divided into 4 groups: 2 control groups received 0.9% NaCl (vehicle; 1 ml/kg/day) or flavocoxid (20 mg/kg/day ip); 2 groups were challenged with cadmium chloride (CdCl2; 2 mg/kg/day ip) and administered with vehicle or flavocoxid. The treatment lasted for 1 or 2 weeks. The testes were processed for biochemical and morphological studies. CdCl2 increased phosphorylated extracellular signal-regulated kinase (p-ERK) 1/2, tumor necrosis factor (TNF)-α, COX-2, 5-LOX, malondialdehyde (MDA), B-cell-lymphoma (Bcl)-2-associated X protein (Bax), follicle-stimulating hormone (FSH), luteinizing hormone (LH), transforming growth factor (TGF) -β3, decreased Bcl-2, testosterone, inhibin-B, occludin, N-Cadherin, induced structural damages in the testis and disrupted the blood-testis barrier. Many TUNEL-positive germ cells and changes in claudin-11, occludin, and N-cadherin localization were present. Flavocoxid administration reduced, in a time-dependent way, p-ERK 1/2, TNF-α, COX-2, 5-LOX, MDA, Bax, FSH, LH, TGF-β3, augmented Bcl-2, testosterone, inhibin B, occludin, N-Cadherin, and improved the structural organization of the testis and the blood-testis barrier. Few TUNEL-positive germ cells were present and a morphological retrieval of the intercellular junctions was observed. In conclusion, flavocoxid has a protective anti-inflammatory, antioxidant, and antiapoptotic function against Cd-induced toxicity in mice testis. We suggest that flavocoxid may play a relevant positive role against environmental levels of Cd, otherwise deleterious to gametogenesis and tubular integrity.

Amyloid β: one of three danger-associated molecules that are secondary inducers of the proinflammatory cytokines that mediate Alzheimer's disease

This review concerns how the primary inflammation preceding the generation of certain key damage-associated molecular patterns (DAMPs) arises in Alzheimer's disease (AD). In doing so, it places soluble amyloid β (Aβ), a protein hitherto considered as a primary initiator of AD, in a novel perspective. We note here that increased soluble Aβ is one of the proinflammatory cytokine-induced DAMPs recognized by at least one of the toll-like receptors on and in various cell types. Moreover, Aβ is best regarded as belonging to a class of DAMPs, as do the S100 proteins and HMBG1, that further exacerbate production of these same proinflammatory cytokines, which are already enhanced, and induces them further. Moreover, variation in levels of other DAMPs of this same class in AD may explain why normal elderly patients can exhibit high Aβ plaque levels, and why removing Aβ or its plaque does not retard disease progression. It may also explain why mouse transgenic models, having been designed to generate high Aβ, can be treated successfully by this approach.

The Effect of Cadmium on COX-1 and COX-2 Gene, Protein Expression, and Enzymatic Activity in THP-1 Macrophages

The aim of this study was to examine the effects of cadmium in concentrations relevant to those detected in human serum on cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) expression at mRNA, protein, and enzyme activity levels in THP-1 macrophages. Macrophages were incubated with various cadmium chloride (CdCl2) solutions for 48 h at final concentrations of 5 nM, 20 nM, 200 nM, and 2 μM CdCl2. The mRNA expression and protein levels of COXs were analyzed with RT-PCR and Western blotting, respectively. Prostaglandin E2 (PGE2) and stable metabolite of thromboxane B2 (TXB2) concentrations in culture media were determined using ELISA method. Our study demonstrates that cadmium at the highest tested concentrations modulates COX-1 and COX-2 at mRNA level in THP-1 macrophages; however, the lower tested cadmium concentrations appear to inhibit COX-1 protein expression. PGE2 and TXB2 production is not altered by all tested Cd concentrations; however, the significant stimulation of PGE2 and TXB2 production is observed when macrophages are exposed to both cadmium and COX-2 selective inhibitor, NS-398. The stimulatory effect of cadmium on COXs at mRNA level is not reflected at protein and enzymatic activity levels, suggesting the existence of some posttranscriptional, translational, and posttranslational events that result in silencing of those genes' expression.

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

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

Preeclampsia induced by cadmium in rats is related to abnormal local glucocorticoid synthesis in placenta

BACKGROUND

Cadmium (Cd) is a major environmental pollutant that causes multiple adverse health effects in humans and animals. In this study, we investigated Cd-mediated toxic effects in rats during pregnancy and endocrine intervention in the placenta.

METHODS

We exposed pregnant rats to intraperitoneal Cd (CdCl2) at various doses (0, 0.25, and 0.5 mg/kg BW/day) from days 5 to 19 of pregnancy and evaluated the maternal-placental-fetal parameters linked to preeclampsia. We measured the corticosterone level in rat serum and placental tissue by sensitive ELISA and also analyzed the expression of glucocorticoid synthesis enzymes in the placenta.

RESULTS

Key features of preeclampsia (PE), including hypertension, proteinuria, glomerular endotheliosis, placental abnormalities and small fetal size, appeared in pregnant rats after injection with 0.5 mg/kg BW/day Cd. The placental corticosterone production and maternal and fetal plasma corticosterone levels were increased in rats treated with 0.5 mg/kg BW/day Cd (P <0.01). The expression of 21-hydroxylase (CYP21) and 11beta-hydroxylase (CYP11B1), enzymes essential for corticosteroid synthesis, were increased in Cd-exposed placenta (P <0.01). 11beta-hydroxysteroid dehydrogenase (11beta-HSD2), a dominant negative regulator of local glucocorticoid levels, was decreased in Cd-exposed placenta (P <0.01).

CONCLUSIONS

Our study demonstrates for the first time that changes in placental glucocorticoid synthesis induced by Cd exposure during pregnancy could contribute to preeclamptic conditions in rats.