Antioxidant effect of estrogen on cytomegalovirus-induced gene expression in coronary artery smooth muscle cells.
BACKGROUND
Pathogens infecting the arterial wall with resultant inflammation may contribute to atherogenesis. Human coronary artery smooth muscle cells (SMCs) infected with human cytomegalovirus (CMV) demonstrate a rapid increase in reactive oxygen species (ROSs), with activation of genes involved in viral replication and inflammation. Because estrogen appears to have antioxidant properties, we wished to determine whether this hormone attenuates SMC responses to CMV infection.


RESULTS
Using confocal microscopy and an intracellular fluorescent dye activated by ROSs, we found that 17beta-estradiol (0.1 to 10 nmol/L) and its stereoisomer 17alpha-estradiol (which has low affinity for the estrogen receptor) dose-dependently inhibited ROS generation in CMV-infected SMCs. These effects were not blocked by the estrogen receptor inhibitor ICI 182,780. 3-Methoxyestrone, which lacks the phenolic hydroxyl group, did not interfere with ROS generation. We found that 17beta-estradiol and 17alpha-estradiol, but not 3-methoxyestrone, prevented binding of nuclear factor (NF)-kappaB to DNA. Furthermore, in SMCs transfected with the reporter constructs 3XkappaB-CAT, MIEP-CAT, or ICAM-CAT, cotransfection with a CMV-IE72 expression plasmid caused promoter and CAT activation. Treatment with 17beta-estradiol and 17alpha-estradiol, but not 3-methoxyestrone, inhibited CAT activity and, in CMV-infected SMCs, prevented IE72 and ICAM-1 protein expression and cytopathic effects.


CONCLUSIONS
These findings indicate that estrogen molecules with an A-ring hydroxyl group have estrogen receptor-independent anti-CMV effects at physiological concentrations by inhibiting ROS generation, NF-kappaB activation, NF-kappaB-dependent transcription, and viral replication. To the extent that chronic infection of the vascular wall with CMV contributes to atherogenesis, these antioxidant actions of estrogen may be of therapeutic importance.
Speir
E
E
Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1650, USA. speire@nih.gov
Yu
Z X
ZX
Takeda
K
K
Ferrans
V J
VJ
Cannon
R O
RO
D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D003587:Cytomegalovirus / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D005453:Fluorescence; D015967:Gene Expression Regulation, Viral / Q000235:genetics*; D006801:Humans; D017874:Immediate-Early Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000235:genetics; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D016328:NF-kappa B / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013629:Tamoxifen / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014764:Viral Proteins; D014779:Virus Replication / Q000187:drug effects
D000975:Antioxidants; D004967:Estrogens; C088645:IE1 protein, cytomegalovirus; D017874:Immediate-Early Proteins; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D014764:Viral Proteins; D013629:Tamoxifen; D018799:Intercellular Adhesion Molecule-1