Acquisition of the monocyte/macrophage phenotype in human mesangial cells

The function of intrinsic glomerular cells in active glomerular inflammatio n may be similar to that of monocytes/macrophages. Mesangial cells have pha gocytic properties and release numerous mediators. In this study we examine d whether human mesangial cells (hMCs) express a monocyte/macrophage phenot ype in active glomerular inflammation. We report that the proto-oncogene c- fms, the macrophage colony-stimulating factor (M-CSF) receptor, which is a characteristic gene of monocytes/macrophages, is expressed in hMCs. Normal unmanipulated hMCs express weak c-fms mRNA by reverse transcriptase-polymer ase chain reaction (RT-PCR), and its expression increases after stimulation with platelet-derived growth factor-BB (PDGF-BB) and epidermal growth fact or (EGF). The expression of c-fms was also demonstrated by flow cytometry w ith a specific polyclonal antibody. By immunohistochemistry, c-fms was prom inently detected in acute glomerulonephritis, IgA nephritis, and lupus neph ritis. These results indicate that hMCs express c-fms in active glomerular inflammation and are consistent with mesangial cells acquiring some macroph age-like characteristics in diseased states.