Estrogen modulation of JE/monocyte chemoattractant protein-1 mRNA expression in murine macrophages

The chemotactic cytokine, monocyte chemoattractant protein-1 (MCP-1), and its murine homologue, JE, have been detected in atherosclerotic lesions but not in normal arteries, implicating that these proinflammatory cytokines may be involved in the pathogenesis of atherosclerosis. Epidemiologic studies reveal that postmenopausal women receiving estrogen replacement for treatment of osteoporosis have a greatly reduced risk of developing cardiovascular disease. Because JE/MCP-1 and estrogen play regulatory roles in the development of atherosclerotic lesions, we chose to examine the effect of estrogen treatment on JE/MCP-1 mRNA expression in macrophages. 17 beta-estradiol (E2) inhibited LPS-stimulated JE/MCP-1 mRNA expression in ANA-1 and J774A.1 murine macrophage cell lines and in thioglycolate-elicited murine peritoneal macrophages. Inhibition of JE/MCP-1 mRNA ranged from 50 to 90%, with a maximal effect occurring at a concentration of 300 pg/ml E2. Conversely, E2 had little effect on LPS-stimulated TNF-alpha mRNA production. Treatment of LPS-stimulated macrophages with moxestrol, an estrogen agonist, resulted in a similar inhibition, and the addition of the estrogen antagonist, tamoxifen, reversed E2 inhibition of JE/MCP-1 mRNA expression. Progesterone failed to inhibit LPS-induced JE/MCP-1 mRNA expression. Immunohistochemical analysis revealed the presence of estrogen receptors in ANA-1 cells, indicating that E2 inhibition of LPS-induced JE/MCP-1 mRNA expression in murine macrophages may be mediated through the estrogen receptor. Thus, another mechanism whereby estrogen exerts antiatherogenic effects may be through prevention of macrophage accumulation in the atherosclerotic lesion.