Nuclear factor-kappa B is essential for up-regulation of interleukin-8 expression in human amnion and cervical epithelial cells

Interleukin-8 (IL-8) is a cytokine which recruits and activates neutrophils into tissue stroma. It is present in uterine tissues and its concentration increases in the third trimester and with labour. The promoter region of the IL-8 gene contains binding sites for the transcription factors, nuclear factor-kappa B (NF-kappaB), activator protein-1 (AP-1) and CCAAT/enhancer-binding protein (C/EBP). These are in close proximity to each other and to the coding region of the gene. This study used site-directed mutagenesis of each of these sites to examine the relative importance of each site in IL-8 gene expression in a cervical cell line and in amnion cells obtained before and after labour. We found that the NF-kappaB site was essential for basal and IL-1 beta -stimulated gene expression in all cell types. Neither of the other binding sites was consistently essential for gene expression but may have an additive role in promoter activity. We conclude that the NF-kappaB binding site is essential for up-regulation of IL-8 gene expression in these uterine cell types. An increase in IL-8 expression has been shown to occur in the uterus in association with parturition and NF-kappaB binding to the promoter may be of importance at this time.