Gamma interferon stimulates monocyte chemotactic protein (MCP-1) in human mesangial cells

Cell-mediated immunity and monocyte infiltration is a prominent histologic feature of several different types of glomerulonephritis. Monocyte influx to the glomerulus correlates with glomerular hypercellularity and proteinuria. Glomerular mesangial cells, in addition to being targets for inflammatory stimuli, are also effector cells that actively participate in glomerular pathology. Mesangial cells release monocyte chemotactic protein (MCP-1). In the present article, we characterized and studied the regulation of MCP-1 released by cultured human mesangial cells. Serum-deprived mesangial cells constitutively release chemotactic activity that is neutralized by specific anti-MCP-1 antibody. An antibody to baboon MCP-1 recognized 16, 15, and 11 kd proteins from concentrated conditioned medium that were consistent with the presence of different forms of MCP-1. Gamma interferon (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 (IL-1) markedly stimulate the release of MCP-1 as measured by a specific and sensitive radioimmunoassay. The release of MCP-1 in response to these cytokines is at least partially dependent on de novo synthesis of the protein because all three cytokines markedly stimulate the expression of MCP-1 mRNA. These data demonstrate that human mesangial cells synthesize and release at least three different forms of MCP-1 and that IFN-gamma and other cytokines regulate the secretion of MCP-1. IFN-gamma and MCP-1 may play a major role in the recruitment and activation of monocytes to the inflamed glomerulus.