BACKGROUND

Information regarding macrophage-mediated regulation of hepatocyte growth factor (HGF) by ovarian steroid hormones in women with endometriosis is limited. Therefore, we investigated the regulation of HGF by steroid hormones in isolated macrophages and stromal cells derived from women with or without endometriosis.

METHODS

We isolated CD68 immunoreactive adherent macrophages in vitro from 46 women with endometriosis and 30 women without endometriosis. Estrogen receptor (ER) and progesterone receptor (PR) expression in macrophages was demonstrated by immunohistochemistry and RT-PCR. Production of HGF in the culture media of basal and ovarian steroid-stimulated macrophages was examined by enzyme-linked immunosorbent assay. Expression of mRNA for HGF and its receptor, c-Met in macrophages and stromal cells in response to ovarian steroid was investigated by RT-PCR. The single and combined effect of HGF and estrogen on the growth of macrophages and stromal cells was analysed by bromodeoxyuridine (BrdU) incorporation.

RESULTS

ER and PR were expressed in isolated macrophages and intact tissue at the protein and mRNA levels. Macrophages derived from women with endometriosis produced significantly higher concentration of HGF (352.2 +/- 4.9 pg/ml) in conditioned media after treatment with estradiol (10(-8) mol/l) than that of basal macrophages (221.5 +/- 32.8 pg/ml, P<0.05) or women without endometriosis (170.6 +/- 2.6 pg/ml, P<0.05). These effects were less evident after treatment with progesterone. Treatment with tamoxifen (10(-6) mol/l) reversed the production of HGF and other macromolecules. Secretion of HGF in response to ovarian steroids was further enhanced after activation with lipopolysaccharide. The mRNA expressions of HGF and its receptor, c-Met, were also detected in macrophages and stroma in response to estrogen, suggesting an autocrine regulation. HGF mRNA expression was higher in cells of women with endometriosis than non-endometriosis women. Bromodeoxyuridine incorporation indicated that exogenous stimulation with HGF and estrogen, either alone or in combination, significantly increased the cell proliferation of both endometrial stroma and macrophages compared to that of non-endometriosis or non-treated cells.

CONCLUSION

These results suggest that besides other inflammatory mediators, ovarian steroids also participate in the production of HGF by peritoneal macrophages which may be involved in the growth of endometriosis either alone or in combination with estrogen.