Estrogen receptor-alpha thymidine and adenine repeat polymorphism and endothelial fibrinolytic regulation in postmenopausal women

Effect of 17β-Estradiol on Endothelial Cell Expression of Inflammation- Related MicroRNA

BACKGROUND

Estrogen plays a protective role in vascular health due, in part, to its regulation of endothelial inflammation. However, the mechanism(s) by which estrogen negatively regulates inflammatory signaling pathways is not completely understood. MicroRNAs (miRNAs) are recognized as sensitive and selective regulators of cardiovascular function, inflammation, and disease, yet the effects of 17β-estradiol on the endothelial miRNA profile are largely unknown.

OBJECTIVE

The aim of this study was to determine the effect of 17β-estradiol on the expression of inflammation-associated miRNAs in endothelial cells in vitro.

METHODS

Human Umbilical Vein Endothelial cells (HUVECs) were treated with media in the absence (control) and presence of 17β-estradiol (100 nM) for 24 hr. Thereafter, endothelial cell release of cytokines (IL-6 and IL-8), the intracellular expression of the central protein inflammatory mediator NF-κB, and the levels of inflammatory-associated miRNAs: miR-126, miR-146a, miR-181b, miR-204, and miR-Let-7a, were determined.

RESULTS

17β-estradiol-treated cells released significantly lower levels of IL-6 (47.6±1.5 pg/mL vs. 59.3±4.9 pg/mL) and IL-8 (36.3±2.3 pg/mL vs. 44.0±2.0 pg/mL). Cellular expression of total NF-κB (26.0±2.8 AU vs. 21.2±3.1 AU) was not different between groups; however, activated NF-κB (Ser536) (12.9±1.7 AU vs. 20.2±2.2 AU) was markedly reduced in 17β-estradiol-treated cells as compared to untreated cells. Furthermore, cellular expressions of miR-126 (1.8±0.3 fold), miR-146a (1.7±0.3 fold), miR-181b (2.1±0.4 fold), miR-204 (1.9±0.4 fold), and miR-Let-7a (1.8±0.3 fold) were markedly increased in response to 17β-estradiol treatment.

CONCLUSION

These data suggest that the anti-inflammatory effect of 17β-estradiol in endothelial cells may be mediated by miRNAs.

Cardiovascular risk in women: the impact of hormone replacement therapy and prospects for new therapeutic approaches

Cardiovascular disease (CVD) is the main cause of death in women. Observational studies of hormone replacement therapy (HT) and data from women with premature ovarian failure have provided support for the principle that estrogen confers protection against the development of CVD in premenopausal women. However, randomised, controlled trials investigating HT in postmenopausal women have failed to demonstrate a benefit of HT in the primary or secondary prevention of CVD. Nevertheless, HT may be effective if targeted at younger perimenopausal women. Research aimed at investigation of the cellular mechanisms of estrogen may result in the discovery of new therapeutic targets that may be able to harness the potential beneficial effects of estrogens in the cardiovascular system. An improved understanding of the distinct processes in the clinical presentation and progress of CVD in women will help develop new targets and enhance the use of current established drugs.