Estrogen attenuates vascular expression of inflammation associated genes and adhesion of monocytes to endothelial cells

Abstract.

Objective

Investigate effects of estrogen at gene expression and functional levels in vascular wall cells treated with bacterial lipopolysaccharide (LPS).

Materials and methods

Aortic segments from ovariectomized mice were treated with LPS for 24 h in the absence or presence of 17β-estradiol (E₂). Gene activity was determined by Affymetrix microarray analysis and real-time RT-PCR. Adhesion of [³H]-thymidine labelled human THP-1 monocytes to mouse bEnd.3 endothelial cells was determined by measuring radioactivity of DNA from co-culture homogenates.

Results

Analysis of global gene expression profiles revealed that 10 nM E₂ attenuates LPS-induced (10 ng/ml) expression of genes coding for well-known acute-phase proteins, such as alpha-trypsin inhibitor heavy chain 4, serum amyloid A3 and lipocalin 2. The E₂-induced down-regulation of these three genes observed by microarray was confirmed by realtime RT-PCR. Treatment with 500 ng/ml LPS increased adhesion of monocytes to endothelial cells more than two fold. Importantly, LPS-induced monocyte adhesion was fully prevented by 50 nM E₂.

Conclusion

Estrogen reduces expression of acute-phase protein genes and inhibits LPS-induced moncocyte adhesion to endothelial cells, suggesting that estrogen might have a vasculoprotective effect via this mechanism.