Cellular mechanisms of cadmium-induced toxicity: a review

Urinary cadmium and mortality from all causes, cancer and cardiovascular disease in the general population: systematic review and meta-analysis of cohort studies

BACKGROUND

Cadmium is a toxic heavy metal distributed in the environment. We conducted a systematic review and meta-analysis to examine the association between urinary cadmium concentration and mortality from all causes, cancer and cardiovascular disease (CVD) in the general population.

METHODS

Studies were identified by searching PubMed and Embase (to 30 March 2015) and the reference lists of retrieved articles. We included prospective studies that reported hazard ratios (HR) with 95% confidence intervals (CI) for the association between urinary cadmium concentration and all-cause, cancer or CVD mortality. A random-effects model was used to combine study-specific results.

RESULTS

Nine cohort studies, including 5600 deaths from all causes, 1332 deaths from cancer and 1715 deaths from CVD, were eligible for inclusion in the meta-analysis. The overall HRs for the highest vs lowest category of urinary cadmium were1.44 (95% CI, 1.25-1.64; I(2 )= 40.5%) for all-cause mortality (six studies), 1.39 (95% CI, 0.96-1.99; I(2 )= 75.9%) for cancer mortality (four studies) and 1.57 (95% CI, 1.27-1.95; I(2 )= 34.0%) for CVD mortality (five studies). In an analysis restricted to six cohort studies conducted in populations with a mean urinary cadmium concentration of ≤1 µg/g creatinine, the HRs were 1.38 (95% CI, 1.17-1.63; I(2 )= 48.3%) for all-cause mortality, 1.56 (95% CI, 0.98-2.47; I(2 )= 81.0%) for cancer mortality and 1.50 (95% CI, 1.18-1.91; I(2 )= 38.2%) for CVD mortality.

CONCLUSIONS

Even at low-level exposure, cadmium appears to be associated with increased mortality. Further large prospective studies of cadmium exposure and mortality are warranted.

Physiochemical basis of human degenerative disease

The onset of human degenerative diseases in humans, including type 2 diabetes, cardiovascular disease, neurological disorders, neurodevelopmental disease and neurodegenerative disease has been shown to be related to exposures to persistent organic pollutants, including polychlorinated biphenyls, chlorinated pesticides, polybrominated diphenyl ethers and others, as well as to polynuclear aromatic hydrocarbons, phthalates, bisphenol-A and other aromatic lipophilic species. The onset of these diseases has also been related to exposures to transition metal ions. A physiochemical mechanism for the onset of degenerative environmental disease dependent upon exposure to a combination of lipophilic aromatic hydrocarbons and transition metal ions is proposed here. The findings reported here also, for the first time, explain why aromatic hydrocarbons exhibit greater toxicity than aliphatic hydrocarbons of equal carbon numbers.

Cadmium transporters in the kidney and cadmium-induced nephrotoxicity

Among the organs in which the environmental pollutant cadmium causes toxicity, the kidney has gained the most attention in recent years. Numerous studies have sought to unravel the exact pathways by which cadmium enters the renal epithelial cells and the mechanisms by which it causes toxicity in the kidney. The purpose of this review is to present the progress made on the mechanisms of cadmium transport in the kidney and the role of transporter proteins in cadmium-induced nephrotoxicity.

The environmental pollutant cadmium induces homeostasis alteration in muscle cells in vitro

BACKGROUND

Cadmium (Cd) is a heavy metal widely distributed throughout the environment as a result of contamination from a variety of sources. It exerts toxic effects in many tissues but scarce data are present as yet on potential effects on skeletal muscle tissue.

AIM

To evaluate the potential alteration induced by Cd in skeletal muscle cells.

MATERIALS AND METHODS

C2C12 skeletal muscle cells were treated with Cd at different times of cellular differentiation and gene expression was evaluated.

RESULTS

Exposure to Cd decreased significantly p21 mRNA expression and strongly up-regulated cyclin D1 mRNA expression in committed cells and in differentiated myotubes. Moreover, myogenin, fast MyHC-IIb and slow MyHC-I mRNAs expression were also significantly decreased both in committed cells and in myotubes. Moreover, Cd exposure induced a strong increase of Pax3, Pax7 and Myf5 mRNAs expression and stimulated an up-regulation of IL6 and TNF-α proinflammatory cytokines.

CONCLUSION

These data lead to hypothesize that environmental Cd exposure might trigger an injury-like event in muscle tissue, possibly by an estrogen receptor-mediated mechanism.