Cadmium induced endothelial dysfunction: consequence of defective migratory pattern of endothelial cells in association with poor nitric oxide availability under cadmium challenge

In vitro and in vivo approaches to assess atherosclerosis following exposure to low-dose mixtures of arsenic and cadmium

Worldwide, millions of people are co-exposed to arsenic and cadmium. Environmental exposure to both metals is linked with a higher risk of atherosclerosis. While studies have characterized the pro-atherosclerotic effects of arsenic and cadmium as single agents, little is known about the potential effects of metal mixtures, particularly at low doses. Here, we used a combination of in vitro and in vivo models to assess the effects of low-dose metals individually and as mixtures on early events and plaque development associated with atherosclerosis. In vitro, we investigated early pro-atherogenic changes in macrophages and endothelial cells with metal treatments. The combined cytotoxic effects of both metals at low concentrations were dose interactive, specifically, synergistic in macrophages, but antagonistic in endothelial cells. Despite this differential behavior across cell types, the mixtures did not initiate early pro-atherogenic events: neither reactive oxygen species generation in macrophages nor adhesion molecule expression on endothelial cells. In vivo, we utilized the well-characterized hyperlipidemic apolipoprotein E knock-out (ApoE-/-) mouse model. Previously, we have shown that low concentrations of arsenic (down to 10 ppb) enhance atherosclerosis in ApoE-/- mice. This model has also been used with cadmium to demonstrate pro-atherogenic effects, although at concentrations above human-relevant exposures. In both sexes, there are some small increases in atherosclerotic lesion size, but very few changes in plaque constituents in the ApoE-/- mouse model. Together, these results suggests that low-dose metal mixtures are not significantly more pro-atherogenic than either metal alone.

miR-210/NF-κB axis: A new direction for regulating cadmium-induced pig artery inflammatory injury

Cadmium (Cd) is a toxic metal pollutant that still exists in the environment. The microRNA (miRNA) is a type of noncoding RNA that plays an important role in gene posttranscriptional regulation and disease development. Although the toxic effects of Cd have been extensively studied, studies on the mechanism of Cd from the perspective of miRNA are still limited. So, we established a Cd-exposure pig model, which confirmed that Cd exposure would cause pig artery damage. The miR-210 with the most reduced expression and the nuclear factor kappa B (NF-κB) that had a targeting relationship with miR-210 were screened. The effect of miR-210/NF-κB on the artery damage induced by Cd exposure was investigated by acridine orange/ethidium bromide staining, reactive oxygen species (ROS) staining, quantitative PCR, and western blotting. The results showed that miR-210 inhibitor, pcDNA-NF-κB could induce ROS overproduction in pig hip artery endothelial cells, thus inducing Th1/Th2 imbalance and necroptosis, leading to increased inflammation, while small interfering RNA-NF-κB played a mitigating role. In conclusion, Cd can induce artery necroptosis and Th1/Th2 imbalance by regulating the miR-210/NF-κB axis, so as to lead to artery inflammatory damage. In this study, we explored the way in which Cd exposure causes artery damage in pig, providing a new perspective on the regulatory damage of miR-210/NF-κB axis.

Cessation Restores Blood Pressure Levels and Endothelial Function Affected by Cadmium Exposure on Rats

Chronic cadmium exposure produces high blood pressure and endothelial damage; however, it is not known whether these effects could be reversed by interrupting the exposure to the metal. Therefore, we evaluate the systolic blood pressure (SBP) and vascular reactivity during and following chronic cadmium-exposure discontinuance. Rats received 100 mg.L^-1 cadmium chloride (CdCl₂) in the drinking water or tap water (Ct) for 30 days and/or tap water for 30 days more. The cadmium plasma content, blood pressure and vascular reactivity of isolated aorta were evaluated. Cadmium exposure increased cadmium plasma content, SBP and aorta contractile responses to phenylephrine, all reversed after suspending exposure. Endothelial removal and nitric oxide synthase (NOS) inhibition increased phenylephrine response both on control and Cd-discontinuation models. Cd-discontinuation group presented increased CAMKII and PKA protein expression, as peNOS^Ser1177. Superoxide dismutase (SOD) incubation reduced contractile response on control group, and catalase incubation enhanced the response to phenylephrine in this group. Meanwhile, both SOD2 and catalase protein expression were increased in Cd-cessation rats. Our findings provide evidence that increased SBP and endothelial dysfunction induced by Cd chronic exposure are reversed by suspending the metal exposure probably due to an improvement of antioxidant enzymes and eNOS function.

Toxic mechanisms of cadmium and exposure as a risk factor for oral and gastrointestinal carcinomas

Incidence and mortality rates of gastrointestinal (GI) and oral cancers are among the highest in the world, compared to other cancers. GI cancers include esophageal, gastric, colon, rectal, liver, and pancreatic cancers, with colorectal cancer being the most common. Oral cancer, which is included in the head and neck cancers category, is one of the most important causes of death in India. Cadmium (Cd) is a toxic element affecting humans and the environment, which has both natural and anthropogenic sources. Generally, water, soil, air, and food supplies are reported as some sources of Cd. It accumulates in organs, particularly in the kidneys and liver. Exposure to cadmium is associated with different types of health risks such as kidney dysfunction, cardiovascular disease, reproductive dysfunction, diabetes, cerebral infarction, and neurotoxic effects (Parkinson's disease (PD) and Alzheimer's disease (AD)). Exposure to Cd is also associated with various cancers, including lung, kidney, liver, stomach, hematopoietic system, gynecologic and breast cancer. In the present study, we have provided and summarized the association of Cd exposure with oral and GI cancers.

Association between exposure to cadmium and risk of all-cause and cause-specific mortality in the general US adults: A prospective cohort study

BACKGROUND

Cadmium has been suggested to accumulate in the body over a lifetime, posing a great threat to human health. So far, few studies have studied the association between cadmium exposure and long-term health outcomes in adults.

OBJECTIVES

To investigate the risk of mortality with blood cadmium level in adults (participants of NHANES, 1999-2014).

METHODS

We evaluated the associations between cadmium and risk of mortality. Data on mortality and cadmium exposure were collected in NHANES database including 39,865 participants. Multivariate Cox regression models were established for calculating hazard ratios (HRs) and 95%CI between cadmium exposure and all-cause and specific-cause mortality outcomes.

RESULTS

Totally, 39,865 individuals with 19,260 males (48.3%) and 20,605 females (51.7%) were included in the study. During a total of 341,017 person-years of follow-up 5,094 deaths were documented, including 1,067 cardiovascular disease (CVD) and 890 cancers. Compared with the lowest quantile of cadmium exposure level group, the adjusted HRs in the highest quantile cadmium exposure level group were 1.73 (95%CI: 1.52-1.97) for all-cause mortality, 1.72 (95%CI: 1.28-2.30) for CVD mortality and 1.87 (95%CI: 1.49-2.36) for cancer mortality, respectively (P for trend: <0.001). Additionally, significant interactions with smoking status in the stratified analyses of all-cause mortality and cancer mortality, age in the stratified analyses of cancer mortality were found (P for interaction: 0.002, <0.001 and 0.012).

CONCLUSIONS

In this nationwide representative sample of the population, we found that higher blood cadmium concentration was associated with increased risks of all-cause and specific-cause mortality. These data further evidence the link between mortality and cadmium concentration. It is of great importance for both policy makers and the public to minimize cadmium exposure, and to reduce long-term adverse health effects.

Induction of ZIP8, a ZIP transporter, via NF-κB signaling by the activation of IκBα and JNK signaling in cultured vascular endothelial cells exposed to cadmium

Cadmium is an environmental pollutant that adversely affects various organs in the human body and is a well-known risk factor for cardiovascular diseases. These disorders are caused by the dysfunction of the vascular endothelial cells that cover the luminal surface of blood vessels. The ZIP transporter ZIP8 is one of the primary importers of cadmium, and its expression appears to be important for the sensitivity of vascular endothelial cells to cadmium. In the present study, we investigated the influence of ZIP8 on cadmium-induced cytotoxicity in vascular endothelial cells, the induction of ZIP8 expression by cadmium, and its action mechanism in vascular endothelial cells. The study revealed that: (1) cadmium cytotoxicity in vascular endothelial cells was potentiated by the overexpression of ZIP8, and the intracellular accumulation of cadmium in the cells was increased; (2) cadmium highly induced the expression of ZIP8, but not other ZIPs; (3) lead and methylmercury moderately induced ZIP8 expression, but the other tested metals did not; (4) the induction of ZIP8 expression by cadmium was mediated by both NF-κB and JNK signaling, and the accumulation of NF-κB in the nucleus was regulated by JNK signaling. Particularly, it was found that cadmium activated NF-κB to transfer it into nuclei and activated JNK to stabilize NF-κB in nuclei, resulting in the induction of ZIP8 expression. This induction appears to be crucial for cadmium cytotoxicity in vascular endothelial cells.

Environmental Contaminants Acting as Endocrine Disruptors Modulate Atherogenic Processes: New Risk Factors for Cardiovascular Diseases in Women?

The number of aged individuals is increasing worldwide, rendering essential the comprehension of pathophysiological mechanisms of age-related alterations, which could facilitate the development of interventions contributing to “successful aging” and improving quality of life. Cardiovascular diseases (CVD) include pathologies affecting the heart or blood vessels, such as hypertension, peripheral artery disease and coronary heart disease. Indeed, age-associated modifications in body composition, hormonal, nutritional and metabolic factors, as well as a decline in physical activity are all involved in the increased risk of developing atherogenic alterations that raise the risk of CVD development. Several factors have been reported to play a role in the alterations observed in muscle and endothelial cells and that lead to increased CVD, such as genetic pattern, smoking and unhealthy lifestyle. Moreover, a difference in the risk of these diseases in women and men has been reported. Interestingly, in the past decades attention has been focused on a potential role of several pollutants that disrupt human health by interfering with hormonal pathways, and more specifically in non-communicable diseases such as obesity, diabetes and CVD. This review will focus on the potential alteration induced by Endocrine Disruptors (Eds) in the attempt to characterize a potential role in the cellular and molecular mechanisms involved in the atheromatous degeneration process and CVD progression.

Soluble curcumin ameliorates motility, adhesiveness and abrogate parthanatos in cadmium-exposed retinal pigment epithelial cells

Cadmium (Cd) is a nonessential transition metal and one of the most toxic environmental pollutants. Industrial, agricultural and urban activities are the main sources of Cd environmental contamination. Multiple deleterious effects of Cd exposure were reported for different cell types and living organisms in a great number of research papers. Cd bioaccumulation hazard is mediated by the relatively long half-life of this metal in an organism. For example, in mammals its half-life lasts for about 10–30 years. Cd exposure affects many tissues. However, some of them, including the central nervous system and sensory organs, are most susceptible to its toxicity. The harmful effects of Cd could be linked to oxidative stress generation and consequently intracellular signalling disruption. Since Cd induces redox imbalance the antioxidants could be a prospective tool to ameliorate Cd cytotoxicity. In present work, we have studied the protective efficacy of soluble curcumin on Cd-caused retinal pigment epithelium (RPE) cells viability, reactive oxygen species production, adhesive and extracellular matrix proteins expression, cell migration and parthanatos level. Low dose (5 µM) of soluble curcumin ameliorated all aforementioned indices of Cd-induced cytotoxicity. Curcumin has restored the RPE cells motility as well as fibronectin and E-cadherin expression. Therefore, the modulation of RPE adhesiveness could be regarded as a cytoprotective effect of curcumin. Furthermore, Cd-caused poly(ADP-ribose) polymerase-1 (PARP-1) suppression and cleaved PARP-1 upregulation were ameliorated by curcumin exposure. Therefore, the protective effect of soluble curcumin could be related, at least partially, to the modulation of PARP activity and inhibition of parthanatos flux. The observed results have demonstrated that low doses of soluble curcumin are a promising tool to protect RPE cells against Cd-caused retinal injury.

The endocrine disruptor cadmium: a new player in the pathophysiology of metabolic diseases

Cadmium (Cd), a highly toxic heavy metal, is found in soil, environment and contaminated water and food. Moreover, Cd is used in various industrial activities, such as electroplating, batteries production, fertilizers, while an important non-occupational source is represented by cigarette smoking, as Cd deposits in tobacco leaves. Since many years it is clear a strong correlation between Cd body accumulation and incidence of many diseases. Indeed, acute exposure to Cd can cause inflammation and affect many organs such as kidneys and liver. Furthermore, the attention has focused on its activity as environmental pollutant and endocrine disruptor able to interfere with metabolic and energy balance of living beings. Both in vitro and in vivo experiments have demonstrated that the Cd-exposure is related to metabolic diseases such as obesity, diabetes and osteoporosis even if human studies are still controversial. Recent data show that Cd-exposure is associated with atherosclerosis, hypertension and endothelial damage that are responsible for cardiovascular diseases. Due to the large environmental diffusion of Cd, in this review, we summarize the current knowledge concerning the role of Cd in the incidence of metabolic and cardiovascular diseases.

Epalrestat suppresses cadmium-induced cytotoxicity through Nrf2 in endothelial cells

Cadmium (Cd) is an industrial and environmental pollutant that targets the vascular endothelium. The vascular system is critically affected by Cd toxicity. Recent studies have indicated an association between Cd and vascular diseases, although the mechanisms of Cd implications in vascular diseases are not clear. The purpose of the present study was to determine whether epalrestat (EPS), which is used for the treatment of diabetic neuropathy, protects against Cd-induced cytotoxicity in bovine aortic endothelial cells (BAECs). In the present study, the effects of EPS at near-plasma concentration were examined on Cd-induced cytotoxicity in BAECs. Cd-induced cytotoxicity was suppressed by pretreatment with EPS. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that serves a role in regulating the expression of glutamate cysteine ligase, the rate-limiting enzyme in glutathione (GSH) synthesis. In a previous study, EPS was demonstrated to increase GSH levels in BAECs in association with the Nrf2 pathway. In the present study, EPS increased GSH levels in BAECs exposed to Cd. The protective ability of EPS against the Cd-induced cytotoxicity disappeared following Nrf2 small interfering RNA transfection. In addition, EPS affected the intracellular levels of Cd, Cd transporter ZIP8 and metallothionein. To the best of our knowledge, the current study demonstrated, for the first time, that EPS suppresses Cd-induced cytotoxicity in BAECs. The upregulation of GSH may be associated with the suppression of Cd-induced cytotoxicity by EPS. From these findings, it may be proposed that the regulation of GSH, ZIP8 and metallothionein by EPS is a promising therapeutic approach to prevent Cd-induced toxicity.

Endothelial Dysfunction Induced by Cadmium and Mercury and its Relationship to Hypertension

Hypertension is an important public health concern that affects millions globally, leading to a large number of morbidities and fatalities. The etiology of hypertension is complex and multifactorial, and it involves environmental factors, including heavy metals. Cadmium and mercury are toxic elements commonly found in the environment, contributing to hypertension. We aimed to assess the role of cadmium and mercury-induced endothelial dysfunction in the development of hypertension. A narrative review was carried out through database searches. In this review, we discussed the critical roles of cadmium and mercury in the etiology of hypertension and provided new insights into potential mechanisms of their effect, focusing primarily on endothelial dysfunction. Although the mechanisms by which cadmium and mercury induce hypertension have yet to be completely elucidated, evidence for both implicates impaired nitric oxide signaling in their hypertensive etiology.

The Role of Antioxidants in the Prevention of Cadmium-Induced Endothelial Dysfunction

Background:

Cadmium is a worldwide spread toxicant that accumulates in tissues and affects many organs, mainly through oxidative damage. Oxidative stress is often associated with cardiovascular diseases and, when it affects vessels, it induces endothelial dysfunction, which, in turn, could precipitate atherosclerosis and hypertension. Therefore, it is reasonable to suggest antioxidant supplementation as a therapy against cadmiuminduced endothelial dysfunction.

Objective:

This literature review aims to present the mechanisms involving oxidative stress in which cadmium induces endothelial dysfunction and the benefits of antioxidant supplementation as a therapeutic strategy against its harmful effects.

Methods:

On PubMed Central, articles that contemplated studies on cadmium intoxication and associated oxidative stress with endothelial dysfunction as well as articles that reported the use of antioxidant supplementation in an attempt to prevent or avoid endothelial dysfunction induced by cadmium exposure were selected.

Results:

Most of the studies that associated cadmium intoxication with endothelial dysfunction suggested oxidative stress as the major mechanism for this damage. Furthermore, experimental studies also revealed that the administration of substances with antioxidant properties, such as ascorbic acid and curcumin, has beneficial effects on the prevention of such dysfunction, reducing reactive oxygen species within the vessels, preventing a reduction in the amount of glutathione and the increase in blood pressure observed in animals exposed to cadmium.

Conclusion:

Antioxidant therapy demonstrated to be a potential treatment to reduce cardiovascular injuries provoked by cadmium, but more studies are needed to determine the best antioxidant substance and dose to treat or avoid this complication.

Cadmium exposure activates NADPH oxidase, renin-angiotensin system and cyclooxygenase 2 pathways in arteries, inducing hypertension and vascular damage

Exposure to high concentrations of cadmium (Cd), widely used in many industries and found in air, food and contaminated water, is not uncommon. Cd damages the cardiovascular system, but the vascular mechanisms involved are not fully understood. This study investigated the mechanisms involved in cardiovascular damage after exposure to high Cd concentrations. Three-month-old male Wistar rats were treated intraperitoneally for 14 days with distilled water (Untreated group) or 1 mg/kg cadmium chloride (Cd group). We investigated the systolic blood pressure (SBP) and vascular reactivity of mesenteric resistance arteries (MRA) and the aorta by analysing contractile and relaxation responses in the absence and presence of the endothelium; we also evaluated pathways involved in vascular tone regulation. Superoxide anion production, COX-2 protein expression and in situ detection of COX-2, AT-1, and NOX-1 were evaluated. Oxidative status, creatinine level and angiotensin-converting enzyme (ACE) activity in plasma were also evaluated. Fourteen-day exposure to a high Cd concentration induced hypertension associated with vascular dysfunction in MRA and the aorta. In both vessels, there was increased participation of cyclooxygenase 2 (COX2), angiotensin II type 1 (AT1) receptor and NOX1. MRA also presented endothelial dysfunction, denoted by impaired acetylcholine-mediated relaxation. All vascular changes were accompanied by increased reactive oxygen species production and COX2, NOX1 and AT1 receptor expression in vascular tissue. Overall, high Cd concentrations induced cardiovascular damage: hypertension, endothelial dysfunction and vascular damage in conductance and resistance arteries, NADPH oxidase, renin-angiotensin system and COX2 pathway activation.

Ameliorative effect of edible Halopteris scoparia against cadmium-induced reproductive toxicity in male mice: A biochemical and histopathologic study

Cadmium (Cd) is a toxic metal affecting the reproductive system. Halopteris scoparia (brown algae) is generally consumed as a salad in the Far East countries. This study was conducted to compare and determine the possible protective effects of H. scoparia and vitamin E and C combination (VEC) against cadmium chloride (CdCl2 )-induced reproductive toxicity. A total of 36 male mice were equally divided into as control, CdCl2 (2 mg/kg), CdCl2  + H. scoparia (900 mg/kg), CdCl2  + VEC (200 mg/kg), H. scoparia alone and VEC alone groups. Blood and testis samples were taken for biochemical, histochemical and immunohistochemical analyses. H. scoparia was also examined for antioxidant activity (by DPPH assay) and mineral/trace element content (by ICP-MS method). CdCl2 exposure caused a significant deterioration in body weight, sperm parameters (count, motility, viability and morphology) (p < .001), histopathology, immunoreactivity and testosterone levels. However, H. scoparia improved CdCl2 -induced deterioration effects more successfully than VEC-treated group. The present study suggests that edible H. scoparia can be used as a natural protective agent against Cd-induced testicular damage by possibly enhancing essential element levels or increasing antioxidant defence system.

Cadmium-induced endothelial dysfunction mediated by asymmetric dimethylarginine

Cadmium (Cd) is a naturally occurring toxic heavy metal with no known essential biological functions. Exposure to Cd increases the risk of cardiovascular disease by disrupting vascular homeostasis at the endothelium. The aim of the study was to evaluate the effect of chronic low-dose Cd on vascular structure and function. Fifty adult male Sprague Dawley rats were grouped and assigned to one of two treatments for 14 weeks. The control group received normal water for 14 weeks while the Cd-treated group received 15 mg Cd/kg B.W. as CdCl₂ in water for 10 weeks. A subset of the Cd-treated group received 15 mg Cd/kg B.W. as CdCl₂ in water for 10 weeks followed by 4 weeks of normal water. Results show an overall decline in vascular function and structure. Withdrawal of Cd treatment showed a considerable restoration of vascular structure and vasorelaxation function. Additionally, asymmetric dimethylarginine (ADMA) bioavailability was found to be lowered over time. Interestingly, the expression of eNOS in the Cd-treated group was found to be significantly elevated during the exposure by more than 3-fold in comparison with that in the control group. This protein expression was similar to the control group after the withdrawal of Cd treatment. Taken together, the results suggest that ADMA, an eNOS inhibitor, may play a role in altering endothelial function in the presence of cadmium. In conclusion, the findings indicate that even at low doses, Cd leads to endothelial dysfunction mediated by ADMA.

Trace Minerals, Heavy Metals, and Preeclampsia: Findings from the Boston Birth Cohort

Background Preeclampsia is a leading contributor to maternal and perinatal morbidity and mortality. In mice experiments, manganese (Mn) and selenium (Se) are protective whereas cadmium (Cd) is promotive for preeclampsia. Epidemiologic findings on these chemical elements have been inconsistent. To confirm experimental findings in mice, we examined associations of trace minerals (Mn and Se) and heavy metals (Cd, lead [Pb], and mercury [Hg]) with preeclampsia in a birth cohort. Methods and Results A total of 1274 women from the Boston Birth Cohort (enrolled since 1998) had complete data on the exposures and outcome. We measured Mn, Se, Cd, Pb, and Hg from red blood cells collected within 24 to 72 hours after delivery. We ascertained preeclampsia diagnosis from medical records. We used Poisson regression with robust variance models to estimate prevalence ratios (PRs) and 95% CIs. A total of 115 (9.0%) women developed preeclampsia. We observed evidence of a dose-response trend for Mn (P for trend<0.001) and to some extent for Cd (P for trend=0.009) quintiles. After multivariable adjustment, a 1 SD increment in Mn was associated with 32% lower risk of developing preeclampsia (PR=0.68; 95% CI, 0.54-0.86), whereas a 1 SD increment in Cd was associated with 15% higher risk of preeclampsia (PR=1.15; 95% CI, 0.98-1.36). Null associations were observed for Se, Pb, and Hg. Conclusions Findings from our cohort, consistent with evidence from mice experiments and human studies, indicate that women with lower blood concentration of Mn or higher Cd are more likely to develop preeclampsia.

Interrelationships of Cadmium, Smoking, and Angina in the National Health and Nutrition Examination Survey, a Cross-Sectional Study

The interrelationships between cadmium biomarker levels, smoking, and myocardial infarction and stroke have been established. In this cross-sectional analysis, we explored the interrelationships of blood cadmium levels, smoking, and angina. We analyzed the National Health and Nutrition Examination Survey (NHANES, 2003-2014) accounting for the multi-staged complex sampling design. Participants 40-79 years of age with blood cadmium levels but without a history of myocardial infarction and/or stroke were included (n = 14,832). We examined blood cadmium levels (3 tertile groups) in relation to 3 (diagnosed, undiagnosed, and composite diagnosed and/or undiagnosed) angina outcomes. Multivariable logistic regression models adjusted for age, diabetes, smoking status, and household income were used to estimate odds ratios (ORs) and their corresponding 95% confidence intervals (CIs). Of 14,832 participants, 741 (4.2%) had positive composite angina. The crude and adjusted ORs comparing those in the lowest tertile (referent group) of blood cadmium to those in the highest tertile for the composite outcome were 1.82 (95% CI 1.42-2.34) and 1.45 (95% CI 1.12-1.88), respectively. These cross-sectional data from a nationally representative sample contribute to the hypothesis that there are interrelationships between smoking, cadmium, and angina.

The molecular and biochemical insight view of grape seed proanthocyanidins in ameliorating cadmium-induced testes-toxicity in rat model: implication of PI3K/Akt/Nrf-2 signaling

The present study aims to evaluate the protective effect of grape seed proanthocyanidins (GSP) on cadmium (Cd)-induced testicular apoptosis, inflammation, and oxidative stress in rats. A total of 24 male Wistar rats were divided into four groups, namely control, GSP (100 mg/kg BW), Cd (5 mg/kg BW), and Cd+GSP. Cd-treated rat testes exhibited a significant increment in oxidative stress mediated inflammation and apoptosis. Pre-administration of GSP exhibit significant protection against the apoptotic and inflammatory damages elicited by Cd and uphold the intercellular antioxidant status in testes. Histological changes were studied and the immunohistochemical staining for caspase 3, HSP70, and eNOS protein expressions were also analyzed to justify the protective action of GSP. Furthermore, GSP prevented DNA damage, and enhanced the expression of antioxidant responsive elements Nrf2/HO-1 by PI3K/Akt-dependent pathway. Therefore, our results suggest that GSP acts as a multipotent antioxidant entity against Cd-induced oxidative testicular toxicity in rats.

Cadmium and atherosclerosis: A review of toxicological mechanisms and a meta-analysis of epidemiologic studies

Cadmium has been proposed to be the one of the factors of atherosclerosis development, although the existing data are still controversial. The primary objective of the present study is the review and the meta-analysis of studies demonstrating the association between Cd exposure and atherosclerosis as well as review of the potential mechanisms of such association. We performed a systematic search in the PubMed-Medline database using the MeSH terms cadmium, cardiovascular disease, atherosclerosis, coronary artery disease, myocardial infarction, stroke, mortality and humans up through December 20, 2017. Elevated urinary Cd levels were associated with increased mortality for cardiovascular disease (HR = 1.34, 95% CI: 1.07-1.67) as well as elevated blood Cd levels (HR = 1.78, 95% CI: 1.24-2.56). Analysis restricted to never smokers showed similar, though more imprecise, results. Consistently, we also observed an association between Cd exposure markers (blood and urine) and coronary heart disease, stroke, and peripheral artery disease. Moreover, Cd exposure was associated with atherogenic changes in lipid profile. High Cd exposure was associated with higher TC levels (OR = 1.48, 95% CI: 1.10-2.01), higher LDL-C levels (OR = 1.31, 95% CI 0.99-1.73) and lower HDL-C levels (OR = 1.96, 95% CI: 1.09-3.55). The mechanisms of atherogenic effect of cadmium may involve oxidative stress, inflammation, endothelial dysfunction, enhanced lipid synthesis, up-regulation of adhesion molecules, prostanoid dysbalance, as well as altered glycosaminoglycan synthesis.

Dose dependent effects of cadmium on tumor angiogenesis

Angiogenesis is crucial for tumor growth and metastasis. Cadmium (Cd) exposure is associated with elevated cancer risk and mortality. Such association is, at least in part, attributable to Cd-induced tumor angiogenesis. Nevertheless, the reported effects of Cd on tumor angiogenesis appear to be either stimulatory or inhibitory, depending on the concentrations. Ultra-low concentrations of Cd (<0.5 μM) inhibit endothelial nitric oxide synthase activation, leading to reduced endothelial nitric oxide production and attenuated tumor angiogenesis. In contrast, low-lose Cd (1-10 μM) up-regulates vascular endothelial growth factor (VEGF)-mediated tumor angiogenesis by exerting sub-apoptotic levels of oxidative stress on both tumor cells and endothelial cells (ECs). The consequent activation of protein kinase B/Akt, nuclear factor-κB, and mitogen-activated protein kinase signaling cascades mediate the increased secretion of VEGF by tumor cells and the up-regulated VEGF receptor-2 expression in ECs. Furthermore, Cd in high concentrations (>10 μM) induces EC apoptosis via the activation of caspase-3, resulting in destruction of tumor vasculature. In this review, we summarize the current knowledge concerning the roles of Cd in tumor angiogenesis, with a focus on molecular mechanisms underlying the dose dependent effects of Cd on various EC phenotypes.

Metabolic Profiling in Association with Vascular Endothelial Cell Dysfunction Following Non-Toxic Cadmium Exposure

This study aimed to determine the metabolic profile of non-toxic cadmium (Cd)-induced dysfunctional endothelial cells using human umbilical vein endothelial cells (HUVECs). HUVECs (n = 6 per group) were treated with 0, 1, 5, or 10 μM cadmium chloride (CdCl₂) for 48 h. Cell phenotypes, including nitric oxide (NO) production, the inflammatory response, and oxidative stress, were evaluated in Cd-exposed and control HUVECs. Cd-exposed and control HUVECs were analysed using gas chromatography time-of-flight/mass spectrometry. Compared to control HUVECs, Cd-exposed HUVECs were dysfunctional, exhibiting decreased NO production, a proinflammatory state, and non-significant oxidative stress. Further metabolic profiling revealed 24 significantly-altered metabolites in the dysfunctional endothelial cells. The significantly-altered metabolites were involved in the impaired tricarboxylic acid (TCA) cycle, activated pyruvate metabolism, up-regulated glucogenic amino acid metabolism, and increased pyrimidine metabolism. The current metabolic findings further suggest that the metabolic changes linked to TCA cycle dysfunction, glycosylation of the hexosamine biosynthesis pathway (HBP), and compensatory responses to genomic instability and energy deficiency may be generally associated with dysfunctional phenotypes, characterized by decreased NO production, a proinflammatory state, and non-significant oxidative stress, in endothelial cells following non-toxic Cd exposure.

MicroRNAs: Impaired vasculogenesis in metal induced teratogenicity

Certain metals have been known for their toxic effects on embryos and fetal development. The vasculature in early pregnancy is extremely dynamic and plays an important role in organogenesis. Nascent blood vessels in early embryonic life are considered to be a primary and delicate target for many teratogens since the nascent blood islands follow a tightly controlled program to form vascular plexus around and inside the embryo for resourcing optimal ingredients for its development. The state of the distribution of toxic metals, their transport mechanisms and the molecular events by which they notch extra-embryonic and embryonic vasculatures are illustrated. In addition, pharmacological aspects of toxic metal induced teratogenicity have also been portrayed. The work reviewed state of the current knowledge of specific role of microRNAs (miRNAs) that are differentially expressed in response to toxic metals, and how they interfere with the vasculogenesis that manifests into embryonic anomalies.

Effects of cadmium on the glial architecture in lizard brain

The glial cells are positioned to be the first cells of the brain parenchyma to face molecules crossing the blood-brain barrier with a relevant neuroprotective role from cytotoxic action of heavy metals on the nervous system. Cadmium is a highly toxic metal and its levels in the environment are increasing due to industrial activities. This element can pass the blood-brain barrier and have neurotoxic activity. For this reason we have studied the effects of cadmium on the glial architecture in the lizard Podarcis siculus, a significant bioindicator of chemical exposure due to its persistence in a variety of habitats. The study was performed on two groups of lizards. The first group of P. siculus was exposed to an acute treatment by a single i.p. injection (2 mg/kg-BW) of CdCl2 and sacrificed after 2, 7 and 16 days. The second one was used as control. The histology of the brain was studied by Hematoxylin/Eosin and Cresyl/Violet stains while the glial structures were analyzed by immunodetection of the glial fibrillary acidic protein (GFAP), the most widely accepted marker for astroglial cells. Evident morphological alterations of the brain were observed at 7 and 16 days from the injection, when we revealed also a decrease of the GFAP-immunopositive structures in particular in the rhombencephalic ventricle, telencephalon and optic tectum. These results show that in the lizards an acute exposure to cadmium provokes morphological cellular alterations in the brain but also a decrement of the expression of GFAP marker with possible consequent damage of glial cells functions.

Interrelation of Cadmium, Smoking, and Cardiovascular Disease (from the National Health and Nutrition Examination Survey)

Cadmium biomarker levels are associated with both cigarette smoking and cardiovascular disease. In this cross-sectional survey, we explore whether the association between cadmium and cardiovascular disease differs between cigarette smoking states. A cross-sectional analysis using the National Health and Nutrition Examination Survey in 2003 to 2012 was performed accounting for the nationally representative complex sampling design. All participants 45 to 79 years old with blood and urinary cadmium levels were included (n = 12,511). We explored the inter-relationships of blood and urine cadmium levels with cigarette smoking and a composite cardiovascular outcome that included self-reported myocardial infarction or stroke or both. We used multivariable logistic regressing models to further adjust for age, income, gender, hypercholesterolemia, body mass index, diabetes, smoking intensity, and time period of smoking cessation. Of the 12,511 participants, 1,330 (8.5%) had previous myocardial infarction or stroke or both. The crude prevalence ratio (PR) comparing those in the lowest tertile of blood cadmium with those in the highest tertile for the composite outcome was 1.73 (95% confidence interval [CI] 1.49 to 2.01). After adjustment for age, gender, income, self-reported diabetes, self-reported hypercholesterolemia, body mass index, and smoking status, the PR was 1.54 (95% CI 1.30 to 1.84). The adjusted PRs for each smoking subgroup were 1.54 (95% CI 1.09 to 2.18) for never-smokers, 1.57 (95% CI 1.11 to 2.23) for current smokers, and 1.31 (95% CI 0.96 to 1.78) for former smokers. These descriptive data from a nationally representative sample suggest that cadmium is related to cardiovascular outcomes even after adjustment for smoking status.

Anti-Apoptotic and Anti-Oxidant Effects of Caffeic Acid Phenethyl Ester on Cadmium-Induced Testicular Toxicity in Rats

Cadmium (Cd) is a serious environmental and occupational contaminant and may represent a serious health hazard to humans and other animals. Cd is reported to induce the generation of reactive oxygen species, and induces testicular damage in many species of animals. The goal of our study was to examine the anti-apoptotic and anti-oxidant effects of caffeic acid phenethyl ester (CAPE) on Cd-induced oxidative stress, apoptosis, and testicular injury in rats. A total of 40 male Wistar albino rats were divided into four groups: control, CAPE alone, Cd-treated, and Cd-treated with CAPE; each group consisted of 10 animals. To induce toxicity, Cd (1 mg/kg body weight) was dissolved in normal saline and subcutaneously injected into rats for 30 days. The rats in CAPE-treated group were given a daily dose of 10 μmol/kg body weight of CAPE by using intraperitoneal injection. This application was continued daily for a total of 30 days. To date, no examinations of the anti-apoptotic and anti-oxidant properties of CAPE on Cd-induced apoptosis, oxidative damage, and testicular injury in rat testes have been reported. CAPE-treated animals showed an improved histological appearance and serum testosterone levels in Cd-treated group. Our data indicate a significant reduction in the number of apoptotic cells in testis tissues of the Cd-treated group with CAPE treatment. Moreover, CAPE significantly suppressed lipid peroxidation, compensated deficits in the anti-oxidant defenses in testes tissue resulted from Cd administration. These findings suggest that the protective potential of CAPE in Cd toxicity might be due to its anti-oxidant and anti-apoptotic properties, which could be useful for achieving optimum effects in Cd-induced testicular injury.

Cadmium overkill: autophagy, apoptosis and necrosis signalling in endothelial cells exposed to cadmium

Apoptosis, necrosis, or autophagy-it is the mode of cell demise that defines the response of surrounding cells and organs. In case of one of the most toxic substances known to date, cadmium (Cd), and despite a large number of studies, the mode of cell death induced is still unclear. As there exists conflicting data as to which cell death mode is induced by Cd both across various cell types and within a single one, we chose to analyse Cd-induced cell death in primary human endothelial cells by investigating all possibilities that a cell faces in undergoing cell death. Our results indicate that Cd-induced death signalling starts with the causation of DNA damage and a cytosolic calcium flux. These two events lead to an apoptosis signalling-related mitochondrial membrane depolarisation and a classical DNA damage response. Simultaneously, autophagy signalling such as ER stress and phagosome formation is initiated. Importantly, we also observed lysosomal membrane permeabilization. It is the integration of all signals that results in DNA degradation and a disruption of the plasma membrane. Our data thus suggest that Cd causes the activation of multiple death signals in parallel. The genotype (for example, p53 positive or negative) as well as other factors may determine the initiation and rate of individual death signals. Differences in the signal mix and speed may explain the differing results recorded as to the Cd-induced mode of cell death thus far. In human endothelial cells it is the sum of most if not all of these signals that determine the mode of Cd-induced cell death: programmed necrosis.

Exposure of Persian sturgeon (Acipenser persicus) to cadmium results in biochemical, histological and transcriptional alterations

Sturgeon is one of the endangered families of fish in the Caspian Sea region, where there is up to 80% of their global caching. Unfortunately, in recent years, increase of pollutants has been resulted in their total population reduction. Due to their benthic nature, sturgeons are at great risk of exposing to contaminants such as cadmium. Despite their endangered status in the Caspian Sea, there are only a few studies on characterizing the relative sensitivity of sturgeons to cadmium. Adverse effects associated with pollution on angiogenesis are mediated by hypoxia inducing factor-1 (HIF-1) and vascular endothelial growth factor (VEGF). In this investigation, gene expression of two distinct HIFs-1, HIF-1α and HIF-2α, and VEGF was investigated at the mRNA transcript levels after exposure of Persian sturgeon (Acipenser persicus) to cadmium. VEGF, HIF-1α and HIF-2α expressions in treated Persian sturgeon were greater than controls. Significant increases (P<0.05) were also observed in cortisol and glucose levels compared to the control group especially in the fish exposed to higher cadmium concentration (800 μg/L). Plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactic acid dehydrogenase (LDH) levels were increased in the cadmium-exposed fish, although the observed increases were not significant between the control and 200 μg/L cadmium treatment at some sampling time points. Gill tissues also showed histopathological changes in the cadmium treatments. Overall, results indicated that cadmium resulted in some alterations in biochemical parameters, mRNA transcript level expression of two important angiogenesis related genes as well as histological alterations in Persian sturgeon.

Low-Dose Cadmium Upregulates VEGF Expression in Lung Adenocarcinoma Cells

Cadmium (Cd) is a heavy metal and environmental toxin. Exposure to Cd has been associated with a variety of human cancers. In this study, we performed in vitro assays to examine the effects of cadmium chloride (CdCl₂) on A549 cells, a human lung adenocarcinoma cell line. Cd does not affect proliferation, migration, or apoptosis of A549 cells at concentrations of 0.1-10 μM. At 0.5 and 1 μM, Cd increases the expression of vascular endothelial growth factor (VEGF) (p < 0.05, p < 0.01, respectively), but not basic fibroblast growth factor (b-FGF) in A549 cells. The conditioned media were collected from the A549 cells treated with 1 μM Cd and were co-cultured with human umbilical vein endothelial cells (HUVECs). Upon treatment with the conditioned media, the proliferation and migration of HUVECs significantly increased (p < 0.01, p < 0.05, respectively), while apoptosis remained unchanged. In addition, 1 μM Cd increases the level of hypoxia inducible factor 1-α (HIF1-α), which is a positive regulator of VEGF expression. Although low-dose Cd does not directly affect the growth of lung adenocarcinoma cells, it might facilitate the development of tumors through its pro-angiogenic effects.

Combination of cadmium and high cholesterol levels as a risk factor for heart fibrosis

The deleterious effects of increased cadmium (Cd) serum levels on the cardiovascular system are proven by epidemiological and basic science studies. Cd exposure of animals and humans is known to impair myocardial function, possibly leading to heart failure. This study aims at investigating the effect of Cd treatment on the cardiac system with emphasis on the combined effect of Cd and high serum cholesterol levels as an important cardiovascular risk factor. Detailed analyses of Cd-induced effects on the heart of ApoE-/- mice fed a high fat diet (HFD), ApoE-/- mice fed a normal diet (ND), and C57BL/6J mice fed a ND revealed proinflammatory and fibrotic changes in the presence of cellular hypertrophy but in the absence of organ hypertrophy. Hypercholesterolemia in ApoE-/- mice alone and in combination with Cd treatment resulted in significant cardiomyocyte cell death. Based on further analyses of heart sections, we conclude that severe hypercholesterolemia in combination with ApoE-/- genotype as well as Cd treatment results in necrotic cardiomyocyte death. These data were supported by in vitro experiments showing a Cd-induced depolarization of the mitochondrial membrane and the permeabilization of the plasma membrane arguing for the occurrence of Cd-induced necrotic cell death. In summary, we were able to show for the first time that the combination of high cholesterol and Cd levels increase the risk for heart failure through cardiac fibrosis. This observation could in part be explained by the dramatically increased deposition of Cd in the hearts of ApoE-/- mice fed a HFD.

Toxic effects of cadmium on testis of birds and mammals: a review

In humans and other mammals, cadmium (Cd) causes various damages to different organs and tissues of the body. This review presents a comprehensive overview on the effect of Cd on the structure of seminiferous tubules, Leydig cells and blood vessels in the testis. The main observation of the effect of Cd is destruction of the seminiferous tubules with severe necrotic areas. Damage is to all stages of developing germ cells by inducing their structural changes and the apoptotic cell death. Sertoli supporting cells are considered the most vulnerable cells. Their damage results in cytoplasmic rearrangement and disruption of inter-Sertoli tight junctions resulting in increased permeability of the blood-testis barrier, structural changes in the Leydig cells and decreased testosterone secretion. After long time of Cd exposure an increase of the amount of interstitial connective tissue occurs. In blood vessels Cd exposure causes various morphological and physiological changes in vascular endothelial cells and smooth muscle cells. In humans and other mammals, the range of effect depends on the dose, route, ways, and duration of exposure. After necrosis of the sensitive cells Cd produced lesions in surrounding tissue and activate free cells. Atrophy of the seminiferous tubules is followed by Leydig cell regeneration and interstitial revascularization. In birds, spermatogenic cells underwent irreversible degeneration or atrophy of seminiferous tubules in the absence of significant vascular lesions.

Protective effects of grape seed extract on cadmium-induced testicular damage, apoptosis, and endothelial nitric oxide synthases expression in rats

This study aims to evaluate the protective effect of grape seed proanthocyanidin extract (GSPE) on cadmium (Cd)-induced testicular apoptosis, endothelial nitric oxide synthases (eNOS) expression, and toxicity in rats. A total of 24 male Wistar rats were divided into four groups, namely, control, Cd (2.5 mg/kg), Cd + GSPE (100 mg/kg/day), and GSPE. Spermatogenesis and mean seminiferous tubule diameter were significantly decreased in the Cd groups. Furthermore, the GSPE-treated animals showed an improved histological appearance in the Cd group. The immunoreactivity of eNOS and the number of apoptotic cells were increased in Cd group. Our data indicate a significant reduction of terminal deoxynucleotide transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end-labeling staining and a decrease in the expression of eNOS in the testes tissue of the Cd group treated with GSPE therapy. Therefore, our results suggest that GSPE acts as a potent protective agent against Cd-induced testicular toxicity in rats.

Cadmium-induced embryopathy: nitric oxide rescues teratogenic effects of cadmium

Although Cadmium (Cd) is a well-known heavy metal pollutant and teratogen, the mechanism behind Cd-mediated teratogenicity remains unknown. Previously, we have reported of the protective role of Nitric oxide (NO), a key signaling molecule in the embryonic developmental process, against Thalidomide-induced teratogenicity. The objective of this study was to obtain a mechanistic in-sight of the antiteratogenic potential of NO against Cd-mediated teratogenicity. To achieve this goal, we first studied the effect of Cd on the vasculature of developing embryos and then we investigated whether Cd mediated its effects by interfering with the redox regulation of NO signaling in the early development milieu. We used a chick embryonic model to determine the time and dose-dependent effects of Cd and NO recovery against Cd assault. The effects of Cd and NO recovery were assessed using various angiogenic assays. Redox and NO levels were also measured. Results demonstrated that exposure to Cd at early stage of development caused multiple birth defects in the chick embryos. Exposure to Cd suppressed endogenous NO levels and cGMP signaling, inhibiting angioblast activation and subsequently impairing yolk sac vascular development. Furthermore, Cd-induced superoxide and lipid peroxidation mediated activation of proapoptotic markers p21 and p53 in the developing embryo. Cd also caused the down-regulation of FOXO1, and up-regulation of FOXO3a and Caspase 3-mediated apoptosis. Addition of exogenous NO through a NO donor was able to blunt Cd-mediated effects and restore normal vascular and embryonic development. In conclusion, Cd-mediated teratogenicity occurs as a result of impaired NO-cGMP signaling, increased oxidative stress, and the activation of apoptotic pathways. Subsequent addition of exogenous NO through NO donor negated Cd-mediated effects and protected the developing embryo.

Changes in compact bone microstructure of rats subchronically exposed to cadmium

Background

Chronic exposure to cadmium (Cd), even at low concentrations, has an adverse impact on the skeletal system. Histologically, primary and secondary osteons as basic structural elements of compact bone can also be affected by several toxicants leading to changes in bone vascularization and mechanical properties of the bone. The current study was designed to investigate the effect of subchronic peroral exposure to Cd on femoral bone structure including histomorphometry of the osteons in adult male rats.

In our study, 20 one-month-old male Wistar rats were randomly divided into two experimental groups. In the first group, young males received a drinking water containing 30 mg of CdCl₂/L, for 90 days. Ten one-month-old males without Cd intoxication served as a control group. After 90 days of daily peroral exposure, body weight, femoral weight, femoral length, cortical bone thickness and histological structure of the femora were analysed.

Results

We found that subchronic peroral application of Cd had no significant effect on body weight, femoral length and cortical bone thickness in adult rats. On the other hand, femoral weight was significantly increased (P < 0.05) in Cd-intoxicated rats. These rats also displayed different microstructure in the middle part of the compact bone where vascular canals expanded into central area of substantia compacta and supplied primary and secondary osteons. Additionally, a few resorption lacunae which are connected with an early stage of osteoporosis were identified in these individuals. Histomorphometrical evaluations showed that all variables (area, perimeter, maximum and minimum diameter) of the primary osteons’ vascular canals, Haversian canals and secondary osteons were significantly decreased (P < 0.05) in the Cd group rats. This fact points to alterations in bone vascularization.

Conclusions

Subchronic peroral exposure to Cd significantly influences femoral weight and histological structure of compact bone in adult male rats. It induces an early stage of osteoporosis and causes reduced bone vascularization. Histomorphometrical changes of primary and secondary osteons allow for the conclusion that the bone mechanical properties could be weakened in the Cd group rats. The current study significantly expands the knowledge on damaging action of Cd on the bone.

Cd²⁺-induced alteration of the global proteome of human skin fibroblast cells

Cadmium (Cd²⁺) is a toxic heavy metal and a well-known human carcinogen. The toxic effects of Cd²⁺ on biological systems are diverse and thought to be exerted through a complex array of mechanisms. Despite the large number of studies aimed to elucidate the toxic mechanisms of action of Cd²⁺, few have been targeted toward investigating the ability of Cd²⁺ to disrupt multiple cellular pathways simultaneously and the overall cellular responses toward Cd²⁺ exposure. In this study, we employed a quantitative proteomic method, relying on stable isotope labeling by amino acids in cell culture (SILAC) and LC–MS/MS, to assess the Cd²⁺-induced simultaneous alterations of multiple cellular pathways in cultured human skin fibroblast cells. By using this approach, we were able to quantify 2931 proteins, and 400 of them displayed significantly changed expression following Cd²⁺ exposure. Our results unveiled that Cd²⁺ treatment led to the marked upregulation of several antioxidant enzymes (e.g., metallothionein-1G, superoxide dismutase, pyridoxal kinase, etc.), enzymes associated with glutathione biosynthesis and homeostasis (e.g., glutathione S-transferases, glutathione synthetase, glutathione peroxidase, etc.), and proteins involved in cellular energy metabolism (e.g., glycolysis, pentose phosphate pathway, and the citric acid cycle). Additionally, we found that Cd²⁺ treatment resulted in the elevated expression of two isoforms of dimethylarginine dimethylaminohydrolase (DDAH I and II), enzymes known to play a key role in regulating nitric oxide biosynthesis. Consistent with these findings, we observed elevated formation of nitric oxide in human skin (GM00637) and lung (IMR-90) fibroblast cells following Cd²⁺ exposure. The upregulation of DDAH I and II suggests a role of nitric oxide synthesis in Cd²⁺-induced toxicity in human cells.

Hypothesis: cadmium explains, in part, why smoking increases the risk of cardiovascular disease

INTRODUCTION

Cigarette smoking is a major risk factor for cardiovascular disease via acute and chronic mechanisms, some of which remain unclear. One plausible but untested hypothesis concerns cadmium (Cd), a component of cigarette smoke, which is injurious to vascular endothelial cells and is independently associated with cardiovascular disease. To contribute to the formulation of this hypothesis, we performed a meta-analysis of the available data that consisted of cross-sectional studies useful to formulate but not test hypotheses.

METHODS

PubMed and Google Scholar were searched by combining the terms smoking, Cd, correlation, blood, human, and tobacco. Following abstract review, 10 cross-sectional studies were identified. We compared serum Cd levels between smokers and nonsmokers using standardized mean differences (SMDs) as well as correlation coefficients between smoking and Cd.

RESULTS

The estimated overall random effects SMD in Cd between smokers and nonsmokers was 1.13 (95% confidence interval [CI], .70-1.56) with significant heterogeneity (Q = 8.6, P < .001). The estimated overall random effects correlation coefficient between smoking and Cd was .54 (95% CI, .30-.72) with significant heterogeneity (Q = 71.3, P < .01).

CONCLUSIONS

Despite major inherent limitations of meta-analyses of cross-sectional studies, we believe that the data contribute to the formulation of the hypothesis that Cd explains, in part, why smokers have an increased risk of cardiovascular disease. Further research, including analytic studies designed a priori are necessary to test the hypothesis.

Nitric oxide protects endothelium from cadmium mediated leakiness

Cadmium targets the vascular endothelium causing endothelial dysfunction and leakiness of endothelial barrier. Nitric oxide plays a major role in mediating endothelial functions including angiogenesis, migration and permeability. The present study investigates the nitric oxide effects on cadmium induced endothelial leakiness. Results of ex vivo and in vitro permeability assays showed that even a sub-lethal dose of cadmium chloride (1 µM) was sufficient to induce leakiness of endothelial cells. Cadmium drastically altered the actin polymerisation pattern and membrane tension of these cells compared to controls. Addition of nitric oxide donor Spermine NONOate (SP) significantly blunted cadmium-mediated effects and recover endothelial cells integrity. Cadmium-induced cytoskeletal rearrangements and membrane leakiness are associated with the low nitric oxide availability and high reactive oxygen species generation. In brief, we show the protective role of nitric oxide against cadmium-mediated endothelial leakiness.

A common response to common danger? Comparison of animal and plant signaling pathways involved in cadmium sensing

Exposure to cadmium results in disturbances in cell homeostasis in all living organisms. The first response to stress factors, including cadmium, is activation of signal transduction pathways that mobilize cell defense mechanisms. The aim of this review is a comparison between the signaling network triggered by Cd in plants and animals. Despite differences in the structure and physiology of plant and animal cells, their cadmium signal transduction pathways share many common elements. These elements include signaling molecules such as ROS, Ca(2+) and NO, the involvement of phospholipase C, mitogen-activated protein kinase cascades, and activation of transcription factors. Undoubtedly, both animals and plants also possess specific signaling pathways. In case of animals, Wnt/β-catenin, sonic hedgehog and oestorgen signaling are engaged in the transduction of cadmium signal. Plant specific signal transduction pathways include signaling mediated by plant hormones. The role of ethylene and jasmonic, salicylic and abscisic acid in plant response to cadmium is also discussed.

Cardiac tissue injury resistance during myocardial infarction at adulthood by developmental exposure to cadmium

It has been suggested that prenatal exposure to cadmium may alter the cardiovascular function during adulthood. Using the left coronary artery ligation model of acute myocardial infarction, we studied the cardiac function of female adult offspring rats exposed to cadmium (30 ppm) during gestation. The cardiac ischemic zone in the control and cadmium-exposed groups was measured 72 h post-ligation using the TPT staining technique. Offspring from cadmium-treated dams showed a significantly smaller infarcted area compared with the control group (7.1 ± 1.5 vs. 19.6 ± 2.8%, P ≤ 0.05). We also performed echocardiographic and biochemical studies, which positively correlated with the differences observed previously. To evaluate whether the effects were associated to pre-infarct tissue damage and/or angiogenic molecules, we performed histological studies and measured the expression of vascular endothelial growth factor (VEGF), and platelet endothelial cellular adhesion molecule-1 (PECAM-1). Results revealed a higher heart vascularization in the exposed offspring that was associated with an increase in PECAM and a decrease in VEGF expression. We conclude that prenatal exposure to cadmium induces fetal adaptive responses involving changes in the expression of some cardiac angiogenic molecules resulting in long-term resistance to infarction.

Toxic and essential trace metals in first baby haircuts and mother hair from Imam Hossein Hospital Tehran, Iran

Hair metal level in newborn and mother pairs from Iran is reported. Toxic metals including cadmium (157 vs. 87.5 μg/kg), mercury (246 vs. 198 μg/kg), copper (14,313 vs. 11,776 μg/kg) and aluminum (52,022 vs. 408,207 μg/kg) were higher in newborn hair when compared to their mothers; suggesting that metals maybe discarded in the fetus as a detoxification method. Comparison with available data from Germany and Poland, and Iraq suggests overall similarities and significant differences in the case of the Iraqi subjects. Public protection from mixture toxicity of metals will be facilitated by studies such as ours.

Cadmium increases HIF-1 and VEGF expression through ROS, ERK, and AKT signaling pathways and induces malignant transformation of human bronchial epithelial cells

Cadmium is categorized as a human carcinogen especially involved in lung cancers. Angiogenesis is considered a fundamental requirement for tumorigenesis, but the mechanisms underlying the tumor angiogenesis induced by cadmium are poorly understood. Using in vitro and in vivo models, we investigated the angiogenic mechanisms of cadmium in human bronchial epithelial cells and tumor formation. Our results demonstrated that cadmium (CdCl(2)) activated extracellular signal-regulated kinases (ERK) and AKT signaling and elevated the expression of a key downstream proangiogenic molecule hypoxia-inducible factor-1 (HIF-1) in immortalized human lung epithelial BEAS-2B cells. Cadmium also induced reactive oxygen species (ROS) production, which could be inhibited by ROS scavengers, catalase and diphenyleneiodonium chloride. Inhibition of ROS generation also attenuated ERK, AKT, p70S6K1 activation, and HIF-1α expression. Similar results were obtained in normal human bronchial epithelial (NHBE) cells, showing that cadmium induced HIF-1 expression via ROS/ERK/AKT signaling pathway. Furthermore, cadmium induced vascular endothelial growth factor expression and transcriptional activation through ROS, ERK, and AKT pathways. Finally, cadmium transformed human bronchial epithelial cells in culture; the transformed cells induced tube formation in vitro, angiogenesis on chicken chorioallantoic membrane, and formed tumors in nude mice. Taken together, the results of this study provide explanation for the role and molecular mechanisms of cadmium in promoting angiogenesis in lung epithelial cells and malignant transformation and will be helpful for improved occupational protection, prevention, as well as chemotherapy of human lung cancers caused by heavy metal cadmium.

NO (nitric oxide): the ring master

The migration and proliferation of endothelial cells affect the process of angiogenesis or the formation of blood vessels. Endothelial cells interact with each other to form ring-like structures in monolayers and tubular structures in matrigels. However, the transit phase between the individual endothelial cells and fully formed tubular structures is yet to be established. Guided by imaging, Western blot analysis, drug perturbation studies and siRNA studies we validate that endothelial ring structures are the fundamental and monomeric units of capillary tubes and nitric oxide is implicated in their fabrication. Giving input from experimental data, we used bagging classifier and information-gain to determine some of the physical and chemical parameters that define these biological structures. Further, we elucidated the implications of endothelial nitric oxide synthase and the NO/sGC/cGMP pathway in the formation of endothelial rings. We conclude that, formation of endothelial ring structure is important for angiogenesis and is mediated by the NO/sGC/cGMP pathway; and further endothelial rings can be used as in vitro models to study angiogenesis.

Cadmium attenuates bradykinin-driven nitric oxide production by interplaying with the localization pattern of endothelial nitric oxide synthase

Cadmium, a ubiquitous heavy metal, interferes with endothelial functions and angiogenesis. Bradykinin is a Ca-mobilizing soluble peptide that acts via nitric oxide to promote vasodilation and capillary permeability. The objective of the present study was to explore the Cd implications in bradykinin-dependent endothelial functions. An egg yolk angiogenesis model was employed to evaluate the effect of Cd on bradykinin-induced angiogenesis. The results demonstrate that 100 nmol/L Cd attenuated bradykinin-dependent angiogenesis. The results of the in vitro wound healing and tube formation assays by using EAhy 926, a transformed endothelial cell line, suggest that Cd blocked bradykinin-mediated endothelial migration and tube formation by 38% and 67%, respectively, while nitric oxide supplementation could reverse the effect of Cd on bradykinin-induced endothelial migration by 94%. The detection of nitric oxide by using a DAF-2DA fluorescent probe, Griess assay, and ultrasensitive electrode suggests that Cd blocked bradykinin-induced nitric oxide production. Fluorescence imaging of eNOS-GFP transfected endothelial cells, immunofluorescence, and Western blot studies of Cd and bradykinin-treated cells show that Cd interfered with the localization pattern of eNOS, which possibly attenuates nitric oxide production in part. Additionally, Ca imaging of Cd- and bradykinin-treated cells suggests that Cd blocked bradykinin-dependent Ca influx into the cells, thus partially blocking Ca-dependent nitric oxide production in endothelial cells. The results of this study conclude that Cd blunted the effect of bradykinin by interfering with the Ca-associated NOS activity specifically by impeding subcellular trafficking of eNOS.

Anti-angiogenic activities associated with exposure of environmental smoke solutions from 2-stroke auto-rickshaw

Angiogenesis, the formation of new blood vessels, is vital for embryonic development and disruption of this process can be a powerful mechanism of abortion. Over the last few decades there has been increasing global concern regarding the public health impact attributed to environmental smoke pollution. However, no study has yet examined the relation between exhaust from 2-stroke auto-rickshaws and angiogenesis. The current experiment was carried out to elucidate the possible detrimental effects of 2-stroke auto-rickshaw smoke solutions (2SARSS) on physiological angiogenesis, using a well-defined chicken chorioallantoic membrane (CAM) assay. Gross computer based 3D image probing and histopathologic modalities were utilized to quantify different detrimental effects of 2SARSS on the fundamental processes of angiogenesis. Macroscopic investigations of 2SARSS treated CAMs revealed severe disruption in the orientation and normal branching pattern of the blood vessels with profound disorganization. Application of 2SARSS caused substantial decrease in the total vascular area of CAM (p<0.001) diameters of the primary, secondary (p<0.01) and tertiary blood vessels (p<0.001) as well as capillary plexuses formation (p<0.001). Evaluation of different 3D parameters of 2SARSS treated CAMs unveiled diminished surface roughness, angular distribution, and height of the Abbott curves. Moreover, histological evaluations of 2SARSS treated CAMs also revealed disruption of the normal architecture of the blood vessel with marked thinning of ectodermal layer and mesodermal extracellular matrix. The anti-angiogenic effects of 2SARSS clearly demonstrate its toxicity to those travelling and/or living in the vicinity of these vehicles and these populations may suffer from several angiogenesis related pathologies.