Mycophenolic acid: a new approach to the therapy of experimental mesangial proliferative glomerulonephritis.

Mycophenolate mofetil (MMF) represents a powerful immunosuppressant in organ transplantation. The aim of this study was to determine the anti-inflammatory effects of MMF on mesangial cells. Cultured rat mesangial cells were exposed to mycophenolic acid (MPA) in concentrations of 0.1 to 10 microM. MPA inhibited the proliferation of these cells in a dose-dependent manner. A maximum of 98% inhibition was obtained by a 2-d exposure of mesangial cells to > or =5 microM MPA. As expected, the addition of > or =75 microM guanosine prevented the antiproliferative effect of MPA completely. Subsequently, in vivo studies were performed in the anti-Thy1.1 nephritis model. Sixty-six male Wistar rats were investigated: healthy rats (n = 15), treated healthy rats (n = 6), nephritic rats (n = 15), and treated nephritic rats (n = 30). MMF therapy (40 mg/kg body wt per d) of nephritic animals was initiated 2 d before (n = 3) and 6 h (n = 15) or 2 d (n = 12) after induction of nephritis. Renal histology was analyzed at days +6 and +9 after initiation of disease. Therapy of nephritic rats by MMF resulted in a significant amelioration of glomerular histology, assessed by glomerular cellularity, synthesis of alpha-smooth muscle actin, extracellular matrix deposition, and glomerular hypertrophy. Proteinuria, expressed as areas under the curve of protein/creatinine ratios versus time, showed a clear tendency toward a reduction by MMF therapy. Healthy control rats were not negatively affected by exposure to MMF. In summary, this study shows that mesangial cell proliferation can be significantly inhibited by MPA in vitro and in vivo. MMF represents a new approach to the therapy of experimental mesangial cell-mediated forms of glomerulonephritis.