Matrix Metalloproteinase Inhibitors Cause Cell Cycle Arrest and Apoptosis in

Inflammation is characterized by an excess of cell proliferation often leading to fibrosis and sclerosis with subsequent loss of organ function. We hypothesized that these features may be ameliorated by induction of cell cycle arrest and apoptosis as result of therapy with matrix metalloproteinase (MMP) inhibi-tors. In our study, mesangial cells and experimental mesangial proliferative glomerulonephritis provided the model of inflam-mation. First, we investigated the effect of the MMP inhibitor BB-1101 in anti-Thy1.1 nephritis. The numbers of apoptotic glomerular cells in nephritic rats increased about 4 and 6 times as a result of BB-1101 therapy, observed 11 and 14 days after induction of disease, respectively. Subsequently, rat mesangial cells were exposed to an MMP inhibitor in vitro. Fluorescence-activated cell sorter analyses of cells exposed to RO111-345