Environmental estrogens or estrogen disrupters have recently received
a great deal of attention because of their potential health impact on
reproductive tissues. Few, if ally, studies have been made on the impa
ct of these compounds on the immune system. We sought to determine the
activities of various environmental estrogens on the modulation of th
e interleukin-1 beta (IL-1 beta) gene in a model monocytic cell line,
hER + IL-1 beta-CAT+. This cell ine stably transfected with the human
estrogen receptor, and an IL-1 beta promoter construct fused to the CA
T reporter gene allows us to monitor the effect of estrogenic compound
s on IL-1 beta promoter activity. 17 beta-Estradiol (E-2) markedly enh
anced lipopolysaccharide- (LPS) induced IL-1 beta promoter-driven CAT
activity in a dose-dependent manner. The mycotoxins c-zearalenol and z
earalenone both exhibited full agonist activity, but at lower potencie
s, with EC50 values of 1.8 and 54 nM, respectively, compared with E-2
at 0.5 nM. In addition, genistein was a very low-potency agonist, havi
ng an EC50 of 1.5 mu M. Similar to the E-2 response, the slope factors
for alpha-zearalenol, zearalenone, and genistein were close to 3.0, s
uggesting posit ve cooperativity in the estrogenic response. The activ
ity of the mycotoxins appeared to be mediated through the estrogen rec
eptor, since both the antiestrogens H1285 and ICI 182,780 effectively
inhibited their agonist activity in a dose-dependent manner. Represent
ative environmental estrogenic compounds both from plant and industria
l sources were ale, tested. Unlike the mycoestrogens, none of the comp
ounds, with the exception of genistein, synergized with LPS to enhance
IL-1 beta promoter activity. When tested for antiestrogenic activity,
the industrial con pound 4-octylphenol was able to antagonize the res
ponse to E-2; however, the response was three orders of magnitude less
potent than H1285. Naringenin, a plant flavonoid, showed little or no
ability to antagonize the response to E-2. Overall, the results show
that some environmental estrogens that display agonist activity in rep
roductive tissue also have an effect on IL-1 gene expression in hemopo
ietic-derived tissue.