In vitro binding of 3H-estradiol to eosinophil and neutrophil granulocytes in various tissues (normal and neoplastic) of newborn and adult rats

Estradiol-stimulated nitric oxide release in human granulocytes is dependent on intracellular calcium transients: evidence of a cell surface estrogen receptor

We tested the hypothesis that estrogen acutely stimulates constitutive nitric oxide synthase activity in human granulocytes by acting on a cell surface estrogen receptor (ER). The release of nitric oxide was measured in real time with an amperometric probe. Exposure of granulocytes to 17β-estradiol stimulated NO release within seconds in a concentration-dependent manner. The NO release was also stimulated by 17β-estradiol conjugated to bovine serum albumin (E2-BSA), which suggests mediation by a cell surface receptor. Tamoxifen, an ER inhibitor, antagonized the action of both 17β-estradiol and E2-BSA, whereas ICI 182,780, an inhibitor of the nuclear ER, had no effect. Using dual emission microfluorometry in a calcium-free medium, the 17β-estradiol–stimulated release of NO from granulocytes was shown to be dependent on intracellular calcium ([Ca2+]i) transients in a tamoxifen-sensitive process. Exposure to BAPTA-AM (1,2bis-(-aminophenoxy)ethans-N,N,N′,N′-tetraacetic acid tetra(acetoxyymethyl) ester), a [Ca2+]i chelator, reduced [Ca2+]i in response to E2-BSA, and depleting [Ca2+]i stores abolished the effect of 17β-estradiol on NO release. Confocal photomicrographs using E2-BSA–FITC (fluorescein isothiocyanate) revealed cell membrane reactivity. Estrogen-stimulated NO release had an immunosuppressive effect, and it initiated granulocyte rounding and loss of adherence in a tamoxifen-sensitive manner. Finally, using reverse transcriptase–polymerase chain reaction, human neutrophil granulocytes expressed ER but not ERβ, suggesting that ER may be the membrane receptor for 17β-estradiol. The study demonstrated that a physiological dose of estrogen down-regulates granulocyte activity by acutely stimulating NO release via the activation of a cell surface ER which is coupled to increases in [Ca2+]i.

Estradiol-stimulated nitric oxide release in human granulocytes is dependent on intracellular calcium transients: evidence of a cell surface estrogen receptor

We tested the hypothesis that estrogen acutely stimulates constitutive nitric oxide synthase activity in human granulocytes by acting on a cell surface estrogen receptor (ER). The release of nitric oxide was measured in real time with an amperometric probe. Exposure of granulocytes to 17β-estradiol stimulated NO release within seconds in a concentration-dependent manner. The NO release was also stimulated by 17β-estradiol conjugated to bovine serum albumin (E2-BSA), which suggests mediation by a cell surface receptor. Tamoxifen, an ER inhibitor, antagonized the action of both 17β-estradiol and E2-BSA, whereas ICI 182,780, an inhibitor of the nuclear ER, had no effect. Using dual emission microfluorometry in a calcium-free medium, the 17β-estradiol–stimulated release of NO from granulocytes was shown to be dependent on intracellular calcium ([Ca2+]i) transients in a tamoxifen-sensitive process. Exposure to BAPTA-AM (1,2bis-(-aminophenoxy)ethans-N,N,N′,N′-tetraacetic acid tetra(acetoxyymethyl) ester), a [Ca2+]i chelator, reduced [Ca2+]i in response to E2-BSA, and depleting [Ca2+]i stores abolished the effect of 17β-estradiol on NO release. Confocal photomicrographs using E2-BSA–FITC (fluorescein isothiocyanate) revealed cell membrane reactivity. Estrogen-stimulated NO release had an immunosuppressive effect, and it initiated granulocyte rounding and loss of adherence in a tamoxifen-sensitive manner. Finally, using reverse transcriptase–polymerase chain reaction, human neutrophil granulocytes expressed ER but not ERβ, suggesting that ER may be the membrane receptor for 17β-estradiol. The study demonstrated that a physiological dose of estrogen down-regulates granulocyte activity by acutely stimulating NO release via the activation of a cell surface ER which is coupled to increases in [Ca2+]i.

Estrogen stimulates neuronal nitric oxide synthase protein expression in human neutrophils

Recent studies have postulated the contribution of nitric oxide (NO) released by the endothelium to the beneficial effects of estrogen. Despite a neuronal-type NO synthase (nNOS) described in neutrophils, less is known about the effect of estrogen in these cells. The aim of the present study was to analyze the expression of nNOS protein in human neutrophils under different estrogenic conditions. We first analyzed nNOS expression in neutrophils obtained from premenopausal women. During the first 2 days of the follicular phase (low circulating estrogen concentrations), nNOS expression in neutrophils was reduced with respect to that found in neutrophils obtained from the same donors during the ovulatory phase (high circulating estrogen concentrations). Moreover, the expression of nNOS protein in neutrophils obtained from postmenopausal women after transdermal estrogen therapy was markedly enhanced with respect to that observed before the treatment. In vitro incubation of neutrophils derived from men for 6 hours with 17beta-estradiol (10(-10) to 10(-8) mol/L) upregulated the expression of nNOS protein. The 17beta-estradiol receptor antagonists, tamoxifen (10(-8) mol/L) and ICI 182780 (10(-8) mol/L), inhibited the upregulation of nNOS protein induced by 17beta-estradiol. The putative functional implication was denoted by a reduced expression of the CD18 antigen on the surface of 17beta-estradiol-incubated neutrophils, which was accompanied by a decreased adhesive capacity. Both effects were prevented by an NO antagonist. In conclusion, the in vivo levels of circulating estrogen concentrations seem to be associated with the level of nNOS protein expression in neutrophils from women. Moreover, low doses of 17beta-estradiol upregulate nNOS protein expression in neutrophils from men. The increased ability of 17beta-estradiol-incubated neutrophils derived from men to produce NO reduced their adhesive properties.

Degranulatory action of estradiol on blood eosinophil leukocytes in vivo and in vitro

The degranulatory activity of estradiol was tested on blood eosinophil leukocytes in vivo and in vitro. Treatment of adult ovariectomized rats with 30 micrograms estradiol/100 g body wt. increased the percentage of degranulated eosinophils from 10% to about 70% at 6 or 24 h after treatment, and increased the rate of in vitro eosinophil degranulation of those eosinophils that were non-degranulated at the time of blood sample collection. The addition of estradiol to blood samples from untreated ovariectomized rats (0.05 micrograms/ml) increased the percentage of eosinophils degranulated in vitro at 1 h of incubation from 20% to near 60%. It is suggested that estrogen acts directly on the eosinophils, probably via specific hormone receptors. Considering the hypothesis that eosinophils are involved in the mediation of a group of responses to estrogen in the uterus, it is proposed that the hormone-induced degranulation of these cells may have physiological implications in the regulation of the intensity and duration of the eosinophil-mediated responses. In addition, estrogen-induced eosinophil degranulation may interfere with the action of eosinophils that have migrated to other target organs (lymphoid organs, etc.) under the action of other agents (glucocorticoid hormones, histamine, etc.) or conditions (immune reactions, etc.).

Estrogen replacement therapy and the mixed lymphocyte reaction

Alterations in immune reactivity may occur in postmenopausal women during estrogen replacement therapy. Fifty-eight women were followed during 6 months of treatment with various synthetic and natural estrogens. Samples of serum showed a dose-dependent inhibitory influence on the mixed lymphocyte reaction. Mean levels of two immunosuppressive serum factors, total cortisol and pregnancy zone protein, were increased during treatment, but individual values were not correlated to depressed lymphocyte reactivity. A direct effect of estrogen on immunoreactive cells is suggested.