PRODUCTION OF MONOCYTE CHEMOATTRACTANT PROTEIN-1 AND MACROPHAGE INFLAMMATORY PROTEIN-1-ALPHA BY INFLAMMATORY GRANULOMA FIBROBLASTS

The formation of hepatic granulomas around persistently deposited Schi stosoma mansoni eggs leads to parenchymal damage, ongoing fibrosis, an d ultimate loss of liver function. In this study, the production of ma crophage inflammatory protein-1 alpha (MIP-1) and monocyte chemoattrac tant protein-1 (MCP-1) by granuloma fibroblasts was examined to establ ish the potential contribution of intragranuloma fibroblasts to the ma intenance of the chronic inflammation. Isolated fibroblasts from dispe rsed acute infection hepatic granulomas were grown in tissue culture f or 3 to 4 weeks and used on the third or fourth passage. We initially surveyed fibroblasts for production of MIP-1 and MCP-1 by reverse tran scription-polymerase chain reaction (RT-PCR) after stimulation with in terleukin (IL)-1, tumor necrosis factor, interferon (IFN)-gamma, IL-4, or IL-10: cytokines found within the granuloma. These studies demonst rated constitutive expression of MCP-1 and differential up-regulation of MIP-1 on cytokine stimulation. Protein expression was then verified by immunohistochemical localization of MIP-1 and MCP-1 in paraformald ehyde-fixed fibroblasts and by direct quantitation of MIP-1 and MCP-1 in culture supernatants by specific ELISAs. These studies demonstrated constitutive expression of MCP-1 in unstimulated and cytokine-stimula ted granuloma fibroblasts. In contrast, IL-1 (0.1 to 2.5 ng/ml), IFN-g amma (10 mu g/ml), and IL-10 (2.5 to 10 ng/ml) were able to induce the significant production of MIP-1 by the granuloma fibroblasts. Interes tingly, normal noninflammatory fibroblasts from uninfected mice showed no significant production of MIP-1 or MCP-1 in response to these cyto kines. These results suggest that granuloma fibroblasts may be phenoty pically altered compared with normal fibroblasts and have a significan t role in leukocyte recruitment, granuloma growth, and maintenance of the egg-induced lesion.