Estrogen regulation of JE/MCP-1 mRNA expression in fibroblasts.

We have recently demonstrated that 17 beta-estradiol (E2) inhibits peritoneal adhesion formation. Because macrophages play a central role in inflammation and wound healing, we chose to investigate whether the E2 could inhibit the expression of JE, the murine monocyte chemoattractant protein-1 (MCP-1). To accomplish this, murine fibroblasts were cultured with physiological concentrations of E2 (3-300 pg/ml) with or without inducers of JE/MCP-1 mRNA expression. Untreated cells failed to express the message, but, following stimulation, a marked increase in JE/MCP-1 mRNA expression was observed. At 10-30 pg/ml, E2 had no effect on JE/MCP-1 mRNA expression in stimulated fibroblasts. In contrast, lower and higher doses of E2 inhibited the expression of JE/MCP-1 mRNA in stimulated fibroblasts. Treatment with tamoxifen reversed the E2-inhibition of expression of the message. These data demonstrate that JE/MCP-1 mRNA expression is controlled, in part, by estrogen and suggest that macrophage recruitment may be affected by circulating levels of E2.

Estrogen suppression of connective tissue deposition in a murine model of peritoneal adhesion formation.

Estrogen's involvement in inflammation and wound healing is poorly understood. To examine the role of estrogen in peritoneal adhesion formation, we gave ovariectomized female C57BL/6 mice time-release pellets containing placebo, 0.05 mg 17 beta-estradiol (low E2), or 5 mg 17 beta-estradiol (high E2) before i.p. injection of talc in saline or saline alone. Analyses of abdominal wall connective tissue thickness and peritoneal cell populations were performed. Talc-treated mice receiving low and high E2 replacement had a decreased amount of abdominal connective tissue deposition (29% and 65% decrease, respectively) as compared with talc-treated mice receiving placebo pellets. At high E2 replacement, the difference in connective tissue deposition was significant statistically (p less than 0.01). Immunohistochemical analysis revealed that the number of macrophages in adhesion tissue was proportionate to the amount of connective tissue present, regardless of the circulating levels of E2. Northern blot analysis of abdominal wall tissue showed that five of six talc-treated animals given placebo expressed mRNA for the murine monocyte chemoattractant protein-1 (MCP-1), JE. Conversely, only one of five talc-treated animals that received E2 replacement expressed JE/MCP-1 mRNA, suggesting that the hormone may inhibit connective tissue deposition by altering the production of chemotactic factors. Furthermore, E2 suppressed talc-induced expression of JE/MCP-1 mRNA in murine macrophages. Since macrophages play a central role in the wound healing process, these studies suggest that E2 inhibition of adhesion formation could be mediated by suppressing macrophage activation and/or recruitment to inflammatory sites.