Inhibition of matrix metalloproteinases attenuates anti-Thy1.1 nephritis

There is accumulating evidence that matrix metallo-proteinases (MMP) play a prominent role in glomerular inflammatory diseases. The aim of the present study was to determine the anti-inflammatory effects of the synthetic MMP inhibitor BB-1101 in acute anti-Thy1.1 nephritis. Sixty-three male Wistar rats were studied: healthy rats (n = 9), treated healthy rats (n = 9), nephritic rats (n = 18), and treated nephritic rats (n = 27). BB-1101 therapy (30 mg/kg body wt per d) of nephritic animals was initiated either 2 d before (n = 18) or 2 d after (n = 9) disease induction. Renal histology was analyzed 11 d after induction of the nephritis, at the peak of MMP-2 production and total glomerular cellularity. Pretreatment of nephritic rats by BB-1101 resulted in a significant amelioration of glomerular histology, assessed by glomerular cellularity, extracellular matrix deposition, and size of glomerular cross-sections. These beneficial effects were less pronounced, but in part still significant, in animals treated by BB-1101 after induction of anti-Thy1.1 nephritis. Proteinuria, expressed as area under the curve of the protein:creatinine ratio versus time, was clearly decreased in both groups of treated nephritic rats. Healthy control rats were not affected by MMP inhibitor treatment. In summary, the present study demonstrates for the first time in vivo that mesangial cell proliferation can be effectively suppressed by MMP inhibition. Thus, MMP inhibition by synthetic compounds may represent a new approach to the therapy of mesangial cell-mediated forms of glomerulonephritis.