Interleukin-1α and -β modulation of luteinized human granulosa cell oestrogen and progesterone biosynthesis

Abstract

This study was designed to test the hypothesis that interleukin-1 alpha (IL-1 alpha) and beta directly affect progesterone, and oestradiol production in cultures of purified human granulosa cells. Luteinized granulosa cells were obtained from women during in-vitro fertilization cycles. Granulosa cells with and without associated white blood cells were cultured in the presence of IL-1 alpha and IL-1 beta (0.5-50 ng/ml) for 48 h. Media were changed at 24 h intervals and assayed for progesterone and oestradiol. In separate experiments, granulosa cell viability was assessed with the tetrazolium salt reduction assay, haemocytometer cell counts, and Trypan blue dye exclusion. Our results indicate that progesterone synthesis by basal and human chorionic gonadotrophin (HCG)-stimulated granulosa cells co-cultured with white blood cells was inhibited by 5.0 ng/ml of IL-1 alpha and IL-1 beta at 48 h of culture. In the presence of white blood cells, granulosa cell oestradiol synthesis was inhibited by IL-1 beta but not IL-1 alpha. Oestradiol was inhibited after both 24 and 48 h of culture and was maximally affected by 5.0 ng/ml of IL-1 beta. In contrast, basal and HCG-stimulated oestradiol production by granulosa cells cultured free of white blood cells was inhibited only by IL-1 alpha. IL-1 alpha at 5.0 ng/ml produced maximal inhibition of basal oestradiol (57%) and HCG-stimulated oestradiol (41%) production at 48 h of culture. Gonadal steroid inhibition by IL-1 alpha and IL-1 beta was not mediated through cytotoxic or antiproliferative effects on granulosa cells. Specificity of the granulosa cell response to IL-1 alpha and IL-1 beta was demonstrated by abrogation of steroid inhibition with anti-IL-1 alpha and IL-1 beta neutralizing antibodies. In conclusion, IL-1 alpha directly inhibited the production of oestradiol by human ovarian granulosa cells. IL-1 alpha and IL-1 beta also exerted indirect effects on steroid production via white blood cells that are usually present in granulosa cell cultures if steps are not taken to remove them. These data support the hypothesis that cytokines play an important role in intra-ovarian regulation of steroid biosynthesis.