Cadmium exposure alters steroid receptors and proinflammatory cytokine levels in endothelial cells in vitro: a potential mechanism of endocrine disruptor atherogenic effect

BACKGROUND

Cadmium (Cd) is a widespread environmental pollutant that causes alterations in human health acting as endocrine disruptor. Recent data suggest that cardiovascular system might be a contamination target tissue, since Cd is found in atheromatic plaques. Thus, the purpose of this study was to evaluate the consequence of Cd exposure of endothelial cells in vitro to evaluate detrimental effect in vascular system by a potential sex-steroid hormone receptor-dependent mechanism(s).

METHODS

To this aim, Human Umbilical Vein Endothelial Cells (HUVECs) were cultured and exposed to several concentrations of cadmium chloride (CdCl₂) for different interval times.

RESULTS

CdCl₂ exposure of HUVECs induced a significant increase of ERβ and Cyp19a1 at both mRNA and protein levels, while a drastic dose-dependent decrease of AR expression level was observed after 24 h of exposure. On the contrary, an increase of PhAR^ser308 as well as a reduction of PhGSK-3β^ser9 and PhAKT^ser473 was detected after 1 h treatment. This effect was consistently reduced by GSK inhibition. Furthermore, CdCl₂ abolished DHT-induced cell proliferation in HUVECs suggesting an antagonist-like effect of Cd on AR-mediated signaling. Remarkable, after 6 h CdCl₂-treatment, a relevant increase in TNF-α, IL-6 and IL-8 mRNA was observed and this effect was blocked by the presence of an ERβ-selective antagonist. Moreover, Cd-induced TxR1 overexpression, likely, correlated with the activation of p38 MAPK/NF-κB pathway.

CONCLUSION

In conclusion, our study demonstrates for the first time that Cd alters sex-steroid hormone receptors level and activity likely affecting intracellular signaling linked to a proinflammatory state in endothelial cells. This alteration might possibly lead to endothelial cell injury and vascular dysfunction and could be a mechanism of gender-specific atherogenic damages induced by endocrine disruptors and, thus, induce atherogenic events with increased risk of cardiovascular diseases in individuals exposed to this endocrine disruptor.

Correction to: Cadmium exposure alters steroid receptors and proinflammatory cytokine levels in endothelial cells in vitro: a potential mechanism of endocrine disruptor atherogenic effect

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Tadalafil modulates aromatase activity and androgen receptor expression in a human osteoblastic cell in vitro model

PURPOSE

Phosphodiesterase type-5 inhibitor (PDE5i) tadalafil administration in men with erectile dysfunction is associated with increased testosterone/estradiol ratio, leading to hypothesize a potential increased effect of androgen action on target tissues. We aimed to characterize, in a cellular model system in vitro, the potential modulation of aromatase and sex steroid hormone receptors upon exposure to tadalafil (TAD).

METHODS

Human osteoblast-like cells SAOS-2 were chosen as an in vitro model system since osteoblasts are target of steroid hormones. Cells were tested for viability upon TAD exposure, which increased cell proliferation. Then, cells were treated with/without TAD for several times to evaluate potential modulation in PDE5, aromatase (ARO), androgen (AR) and estrogen (ER) receptor expression.

RESULTS

Osteoblasts express significant levels of both PDE5 mRNA and protein. Exposure of cells to increasing concentrations of TAD (10(-8)-10(-7) M) decreased PDE5 mRNA and protein expression. Also, TAD inhibited ARO mRNA and protein expression leading to an increase in testosterone levels in the supernatants. Interestingly, TAD increased total AR mRNA and protein expression and decreased ERα, with an increased ratio of AR/ER, suggesting preferential androgenic vs estrogenic pathway activation.

CONCLUSIONS

Our results demonstrate for the first time that TAD decreases ARO expression and increases AR protein expression in human SAOS-2, strongly suggesting a new control of steroid hormones pathway by PDE5i. These findings might represent the first evidence of translational actions of PDE5i on AR, which leads to hypothesize a growing relevance of this molecule in men with prostate cancer long-term treated with TAD for sexual rehabilitation.

The endocrine disruptor cadmium alters human osteoblast-like Saos-2 cells homeostasis in vitro by alteration of Wnt/β-catenin pathway and activation of caspases

PURPOSE

The pollutant Cadmium (Cd) is widespread in the environment and causes alterations of human health by acting as an endocrine disruptor. Bone tissue seems to be a crucial target of Cd contamination. Indeed, we have previously demonstrated that this endocrine disruptor induces osteoblast apoptosis and necrosis. Thus, aim of this study was to further evaluate the effect of Cd on osteoblasts homeostasis, investigating potential modification of the Wnt/β-catenin intracellular pathway, the intracellular process involved in programmed cellular death and the cytoskeletal alterations.

MATERIAL AND METHODS

To this purpose, human osteoblastic Saos-2 cells, a human osteosarcoma osteoblast-like cell line, were cultured and treated with Cd.

RESULTS

Osteoblastic cells were treated for 6 h with 10μM Cd, which induced nuclear translocation of β-catenin and increased expression of Wnt/β-catenin target genes. Longer exposure to the same Cd concentration induced osteoblastic cell apoptosis. To better characterize the intracellular events involved in these Cd-induced alterations, we evaluated the effect of Cd exposure on actin filaments and proteins associated to cytoskeletal actin, characterized by the presence of LIM domains. Long (15, 24 h) exposure of osteoblasts to Cd reduced LIM proteins expression and induced actin filaments destruction and a significant caspase-3 activation after 24 h. In addition, to prove that Cd induces osteoblastic cells apoptosis after long exposure, we performed TUNEL assay which demonstrated increase of cell apoptosis after 24 h.

CONCLUSION

In conclusion, our study shows that osteoblasts exposed to Cd for short intervals of time demonstrated an increase in cell proliferation through a Wnt/β-catenin dependent mechanism, likely as a compensatory mechanism in response to cell injury. Longer exposure to the same Cd concentration induced cells apoptosis through cytoskeleton disruption-mediated mechanisms and caspase activation.

C-reactive protein and embolization during carotid artery stenting. A serological and morphological study

INTRODUCTION

High-sensitivity C-Reactive Protein (hsCRP) levels are correlated with vulnerable carotid plaques, although their impact on the outcome of carotid revascularization is unknown. The aim of our study was to investigate the correlation between hsCRP and embolization during carotid artery stenting (CAS).

METHODS

Patients with symptomatic carotid stenosis were submitted to CAS with distal protection filters. Serum hsCRP was analysed prior to CAS and patients were divided into two groups: Class I, patients presenting hsCRP < 5 mg/l and, Class II, patients presenting hsCRP≥5 mg/l. Plaques were categorised by ultrasound grey scale measurement as homogenous and dishomogenous. Afterwards CAS filters were analyzed microscopically and ultrastructurally to determine the type and the amount of debris present, based on percentage of surface involvement (SI) and pore occluded (PO) by embolic material.

RESULTS

Fourteen patients underwent uneventful CAS, with a mean hsCRP of 11.5±18.4 mg/l. Eight patients were in Class I and six in Class II. All filters had microscopic debris. SI was 25.4% in Class I and 33.3% in Class II (p=ns), PO 22.9% and 33.3% respectively (p=0.049). Patients in Class II who also had a dishomogenous plaque showed greater SI and PO compared with patients in Class I with homogenous plaque (35.0% vs. 21.8% and 40.4% vs. 22.7% respectively, p<0.05). Microscopically embolic material was identified as atherosclerotic plaque fragments and platelet aggregates and was similar in both groups.

DISCUSSION

High hsCRP levels are associated with significantly greater embolization during CAS in symptomatic patients, particularly in dishomogenous plaque. Although these results need further investigation due to the limited number of enrolled patients, this study suggests that CAS may not be indicated as a method of carotid revascularization in this setting.