OBJECTIVE Glomerulosclerosis is characterized by extracellular matrix accumulative and is often associated with mesangial cell proliferation. Curcumin showed a protective effect on anti-glomerular basement membrane (anti-GBM) nephritis in vivo, although their cellular localization and mechanism of action is still unclear. In this study, a glomerular mesangial cell line derived from fetus was used to determine whether curcumin could inhibit the cell proliferation and alter the extracellular matrix turnover. METHODS The cell activity was determined with MTT method. Mesangial cells were cultured in vitro and incubated with 0, 3.125, 6.25, 12.5, 25, 50, 100 and 200 micromol/L curcumin. In addition,human mesangial cells were cultured with or without LPS (10 microg/ml) in presence or absence of various concentrations of curcumin (4, 16 and 200 micromol/L), respectively. The supernatant and cells were collected. Then, the levels of the collagen type IV and III protein in the supernatant were determined by using enzyme-linked immunosorbent assay and the IL-1 beta and MCP-1 mRNA in the cells was measured by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) after subconfluent quiescent mesangial cells were incubated with various concentrations of curcumin for 24 h in vitro. RESULTS Curcumin at the concentration equal to or over 6.25 micro mol/L was able to inhibit the proliferation of mesangial cells in a dose-dependent manner, the optical density according to the sequential concentrations of curcumin was 0.65 +/- 0.02, 0.62 +/- 0.04, 0.56 +/- 0.01, 0.53 +/- 0.02, 0.51 +/- 0.03, 0.44 +/- 0.05, 0.41 +/- 0.07 and 0.38 +/- 0.06. Without any stimulation, human mesangial cells secreted some collagen type IV and III (10 +/- 9.13 ng/ml and 29.5 +/- 0.58 ng/ml, respectively) and expressed some MCP-1 mRNA, but did not express IL-1 beta mRNA. LPS increased the expression of collagen type IV and III in the culture medium of mesangial cells in vitro [(138.75 +/- 23.23) ng/ml and (38.25 +/- 5.38) ng/ml] and up-regulated the IL-1 beta and MCP-1 mRNA expression [(16.91 +/- 1.68)% and (76.6 +/- 6.59)%]. Yet curcumin could significantly decrease collagen type IV and III in the supernatant of cultured mesangial cells induced by LPS (20.5 +/- 1.00, P < 0.05 and 20.5 +/- 4.12 ng/ml, P < 0.05) and down-regulated the mRNA expression of IL-1 beta and MCP-1 in mesangial cells induced by LPS (P < 0.01). CONCLUSIONS Curcumin could inhibit the human mesangial cell proliferation and alter the extracellular matrix turnover, meanwhile it could down-regulate the IL-1 beta and MCP-1 mRNA expression induced by LPS, which may be valuable in decreasing the progression of glomerulosclerosis.