Peritoneal macrophages induce RANTES (regulated on activation, normal T cell expressed and secreted) chemokine gene transcription in endometrial stromal cells

Peritoneal fluid macrophages (PFM) are activated in women with endometriosis, in whom they are thought to mediate or exacerbate inflammation. The effect of PFM on endometrial stromal cells (ESC) was studied using a coculture model to evaluate the influence of IL-1β and other macrophage-derived cytokines on the transcriptional activation of the human RANTES (regulated on activation, normal T cell expressed and secreted) gene. Normal endometrial biopsies from four patients were used to prepare stromal cell cultures, and pelvic fluid was collected to isolate peritoneal macrophages. A full length (-940 bp) human RANTES promoter construct provided an indicator of transcriptional activation in luciferase reporter transfection assays. Without lipopolysaccharide (LPS), cocultures with PFM had no effect on ESC RANTES gene expression. However, when PFM were treated with LPS within the coculture apparati, ESC RANTES promoter activity was increased more than 2-fold (P < 0.05). The addition of IL-1 receptor antagonist abrogated activation of the RANTES luciferase transgene by LPS-induced PFM products (P < 0.05). We identified IL-1 from PFM as a major stimulus to initiate ESC RANTES gene expression in cocultures. We postulate that PFM stimulation of RANTES production by ESC could lead to a self-propagating recruitment of inflammatory cells that contribute to the development and progression of endometriotic lesions.