IL-1β induction of RANTES (regulated upon activation, normal T cell expressed and secreted) chemokine gene expression in endometriotic stromal cells depends on a nuclear factor-κB site in the proximal promoter

A complex network of cytokines mediates immunoregulatory responses in the pathogenesis of endometriosis. RANTES (regulated upon activation, normal T cell expressed and secreted) is a chemoattractant for monocytes and T cells. Endometriotic lesions express RANTES, and its concentration in peritoneal fluid correlates with the severity of endometriosis. We investigated the influence of IL-1β, a potent macrophage cytokine, on RANTES production in endometriotic stromal cells and determined the region of the RANTES promoter responsible for IL-1β action. RANTES mRNA was induced 5-fold in endometriotic stromal cells, and the conditioned medium RANTES protein concentrations were 12-fold higher in IL-1β-treated endometriotic stromal cells vs. untreated controls (P < 0.05). IL-1β activated the full-length (-940 bp) RANTES promoter as well as a truncated 456-bp 5′-flanking construct by 2-fold. Mutagenesis of a nuclear factor-κB response element at -30 bp abolished the IL-1β effect, whereas mutation of a nearby TNF response element did not affect the IL-1β induction. An IL-1β time-course Western assay revealed a rapid diminution of IκB (endogenous inhibitor of nuclear factor-κB) in endometriotic stromal cells. Overexpression of IκB in endometriotic stromal cells inhibited the IL-1β response of the RANTES gene promoter. Transcription of RANTES mRNA is up-regulated by IL-1β via a nuclear factor-κB response element in the proximal RANTES gene promoter. These results demonstrate a feed-forward regulatory loop in the pathogenesis of endometriosis by which IL-1β produced from activated macrophages can lead to further macrophage recruitment via RANTES production in endometriotic stromal cells.