PRODUCTION OF ADRENOMEDULLIN IN MACROPHAGE CELL-LINE AND PERITONEAL MACROPHAGE

We demonstrate that adrenomedullin (AM) is produced and secreted from cultured murine monocyte/macrophage cell line (RAW 264.7) as well as m ouse peritoneal macrophage. Immunoreactive (IR) AM secreted from RAW 2 64.7 cells was chromatographically identified to be native AM. To eluc idate the regulation mechanism of AM production in macrophage, we exam ined the effects of various substances inducing differentiation or act ivation of monocyte/macrophage. Phorbol ester (TPA), retinoic acid (RA ), lipopolysaccharide (LPS), and interferon-gamma (IFN-gamma) increase d AM production 1.5-7-fold in RAW 264.7 cells in a dose- as well as ti me-dependent manner. By LPS stimulation, the AM mRNA level in RAW 264. 7 cells was augmented up to 7-fold after 14 h incubation. RA exerted a synergistic effect when administered with TPA, LPS, or IFN-gamma, whe reas IFN-gamma completely suppressed AM production in RAW 264.7 cells stimulated with LPS. Dexamethasone, hydrocortisone, estradiol, and tra nsforming growth factor-beta dose-dependently suppressed AM production in RAW 264.7 cells. AM production was also investigated in mouse peri toneal macrophage. Primary mouse macrophage secreted IR-AM at a rate s imilar to that of RAW 264.7 cells, and its production was enhanced 9-f old by LPS stimulation. AM was found to increase basal secretion of tu mor necrosis factor alpha (TNF-alpha) from RAW 264.7 cells, whereas AM suppressed the secretion of TNF-alpha and interleukin-6 from that sti mulated with LPS. Thus, macrophage should be recognized as one of the major sources of AM circulating in the blood. Especially in cases of s epsis and inflammation, AM production in macrophage is augmented, and the secreted AM is deduced to function as a modulator of cytokine prod uction.