EFFECT OF ESTROGENS ON IL-1-BETA PROMOTER ACTIVITY

It is well documented that steroid hormones modulate cytokine gene exp ression. In some tissues estrogens are known to suppress cytokine prod uction while in other tissue types, cytokine expression is enhanced by the hormone. This study was conducted to investigate the regulatory m echanisms which underlie the modulation of the interleukin-1 beta (IL- 1 beta) gene at the transcription level. To accomplish this, the macro phage cell line RAW264.7, which appeared insensitive to 17 beta-estrad iol (E-2) treatment, was stably transfected with the human estrogen re ceptor (ER) and an IL-1 beta promoter-CAT reporter construct. E-2 mark edly enhanced LPS-induced IL-1 beta promoter-driven CAT activity in an E-2 dose dependent manner. This responsiveness was estrogen specific since no synergism was observed between LPS and the sex steroids testo sterone or progesterone while the estrogen analogue 17 alpha-estradiol stimulated only at 10 to 100 times the amount required for 17 beta-E- 2. Several antiestrogens, H1285, ICI 182 780, and tamoxifen inhibited the estrogen stimulated enhancement of IL-1 beta promoter activity in a dose-dependent manner, indicating that this effect was indeed mediat ed through the ER in a ligand dependent manner. The estrogenic effect appeared to be indirect and time dependent since the addition of E-2 w as required hours prior to LPS stimulation; addition of E-2 and LPS at the same time resulted in a greatly reduced estrogenic effect. The es trogen metabolites 17-epiestriol and 16-keto-17 beta-E-2 displayed an estrogenic response virtually indistinguishable from E-2. 4-Hydroxyest radiol displayed activity only at 100-fold the concentration of E-2 wh ile 2-hydroxyestrone showed no activity at any of the concentrations t ested. Overall the results demonstrate that E-2 and some metabolites o f E-2 synergize with LPS to markedly enhance IL-1 beta promoter activi ty through ER mediated processes. (C) 1998 Elsevier Science Ltd. All r ights reserved.