An anti-inflammatory role of interleukin-4 in the human ovarian surface epithelium
G Papacleovoulou, H Critchley, S Hillier & I Mason
Based on the hypothesis that incessant ovulation and ovulation-related inflammation are associated with the development of epithelial ovarian cancer, we have investigated in vitro the role of androgen and progesterone pre-receptor metabolism and steroid receptor signalling in human ovarian surface epithelium (hOSE) wound healing. Ovulation-associated injury was mimicked with exposure of primary hOSE cells to interleukin-1α, whereas post-ovulatory healing was induced with interleukin-4 treatment. Histological, gene expression, protein and activity assays focusing on 3β-hydroxysteroid dehydrogenase (3β-HSD) types 1 and 2, androgen (AR) and progesterone (PR) receptors were performed.
3β-HSD protein was immunodetected in hOSE with 3β-HSD1 mRNA expressed at higher levels than 3β-HSD2 mRNA in accordance with preference of this isotype in non-steroidogenic tissues. Interleukin-1α attenuated 3β-HSD1 mRNA and induced 3β-HSD2 mRNA, without affecting total 3β-HSD protein or activity. Moreover, interleukin-1α did not affect AR or PR expression levels, thereby implying maintenance of steroid balance during ovulation. Interleukin-4 substantially stimulated 3β-HSD1 and 3β-HSD2 mRNA along with total 3β-HSD protein and activity. Simultaneous attenuation by interleukin-4 of AR without affecting PR suggested that interleukin-4-induced 3β-HSD promotes progesterone rather than androgen signalling, highlighting an effective mechanism to counteract inflammation-associated ovulation. Intriguingly, interleukin-4-mediated effects on 3β-HSDs and AR mRNA were reversed by the p38 MAPK inhibitor, SB203580, whilst interleukin-1α effects were reversed by Bay117082, a specific NFκB pathway inhibitor, indicating involvement of these signalling transduction pathways in the regulation of 3β-HSD transcripts. A further anti-inflammatory role of interleukin-4 in hOSE was demonstrated by its ability to induce lysyl oxidase mRNA, and also to attenuate interleukin-1α-induced inflammatory cyclooxygenase-2 mRNA, molecules respectively involved in extracellular matrix deposition and breakdown.
In summary, interleukin-4-increased 3β-HSD expression could be a critical mechanism controlling progesterone bioavailability and signalling during post-ovulatory events involving a fundamental role for p38 MAPK kinase and with potential therapeutic advantage in ovarian cancer.