Tumor necrosis factor-alpha activates nuclear factor-kappaB but does not regulate progesterone production in cultured human granulosa luteal cells

Abstract

Background. The role of tumor necrosis factor-α (TNF-α) in granulosa luteal cell function and steroidogenesis is still controversial. Our aim was to examine the steroidogenic response, together with the simultaneous expression and activation of nuclear factor-κB (NF-κB), in cultured human granulosa luteal cells (GLCs) following administration of TNF-α.

Materials and methods. This prospective controlled study was conducted in the Human Reproduction Division at the Institute of Maternal and Child Research, Faculty of Medicine, University of Chile and the San Borja Arriarán Hospital, National Health Service, Santiago, Chile. GLCs were obtained from aspirates of follicles from women undergoing in vitro fertilization (IVF). Thirty-two women undergoing IVF for tubal-factor and/or male-factor infertility participated in this study. Protein levels of NF-κB, the NF-κB inhibitor IκBα and steroidogenic acute regulatory protein (StAR) were determined by Western blot and localization of NF-κB was studied by indirect immunofluorescence. Progesterone production was determined by radioimmunoassay.

Results. TNF-α did not affect the expression of StAR protein or the synthesis of progesterone. NF-κB was expressed in the GLCs and activated by TNF-α, resulting in degradation of IκBα and mobilization of the p65 NF-κB subunit into the nucleus.

Conclusions. These results indicate that TNF-α did not modulate steroidogenesis in cultured human GLCs. However, NF-κB was activated by TNF-α. Therefore the activation of NF-κB via the TNF-α pathway is likely associated with other preovulatory granulosa cell processes important for human ovarian function.

Keywords:

• Steroidogenesis
• granulosa luteal cells
• TNF-α
• NF-κB
• IκBα