Renal matrix metalloproteinase activity is unaffected by experimental ischemia-reperfusion injury and matrix metalloproteinase inhibition does not alter outcome of renal function.

BACKGROUND: Ischemia-reperfusion injury can lead to organ damage, such as delayed graft function in kidney transplantation. Reactive oxygen species that play a key role in this disorder may directly activate latent matrix metalloproteinases (MMP). In the kidney, little is known about the role of MMP in ischemia-reperfusion. Therefore, the aim of our study was to analyze activity/expression of MMP and to assess their functional role by the use of the MMP inhibitor BB-94 (Batimastat). METHODS: Renal ischemia was induced by left renal pedicle occlusion for 60 min, preceded by right nephrectomy. Thirty-two female Sprague-Dawley rats were analyzed: sham-operated rats (n = 8), treated sham-operated rats (n = 4), ischemic rats (n = 12), and treated ischemic rats (n = 8). Batimastat therapy (30 mg/kg body weight/day) was initiated 2 days prior to induction of ischemia. Animals were sacrificed 12 h (n = 8) and 24 h (n = 24) after ischemia for analyses of MMP activity/expression and of plasma creatinine levels. RESULTS: We found no evidence for an alteration in the activity or expression of MMP as a result of renal ischemia-reperfusion. Importantly, plasma creatinine levels significantly increased to a mean of 374 +/- 61 micromol/l in ischemic rats after 24 h, almost identical to the BB-94-treated ischemic rats (384 +/- 36 micromol/l). The creatinine levels in sham-operated rats remained within normal limits. CONCLUSION: MMP play no role during the early phase of experimental renal ischemia-reperfusion injury.

Proinflammatory effects in experimental mesangial proliferative glomerulonephritis of the immunosuppressive agent SDZ RAD, a rapamycin derivative.

BACKGROUND/AIM: The new immunosuppressant SDZ RAD, a rapamycin derivative, inhibits growth factor driven cell proliferation. SDZ RAD designed for transplantation may also be a candidate agent to treat inflammatory kidney diseases. Therefore, we investigated the effects of SDZ RAD in two different animal models of glomerulonephritis, in anti- Thy1.1 nephritis and in acute puromycin aminonucleoside (PAN) nephrosis. METHODS: Eighty-seven male Wistar rats were investigated. Anti-Thy1.1 nephritis: healthy rats (n = 9), SDZ RAD-treated healthy rats (n = 6), nephritic rats (n = 9), SDZ RAD placebo treated nephritic rats (n = 6), SDZ RAD-pretreated nephritic rats (n = 9), and early (n = 6) as well as delayed (n = 6) SDZ RAD-posttreated nephritic rats. PAN nephrosis: healthy rats (n = 6), SDZ RAD-treated healthy rats (n = 6), nephritic rats (n = 12), and SDZ RAD-pretreated nephritic rats (n = 12). In a separate study, 12 male Sprague-Dawley rats were analyzed in anti-Thy1.1 nephritis: healthy rats (n = 3), nephritic rats (n = 3) and pretreated nephritic rats (n = 6). SDZ RAD and SDZ RAD placebo were given at single doses of 2.5 mg/kg body weight per day by gavage. The experiments lasted until days +2 and +9 after induction of anti-Thy1. 1 nephritis and until day +13 in the case of PAN nephrosis. RESULTS: In anti-Thy1.1 nephritis, SDZ RAD demonstrated marked proinflammatory effects in a time-dependent manner, as reflected by severe focal damage to glomerular histology including inhibition of mesangial cell proliferation, reduction of creatinine clearance, and increase in plasma creatinine levels as well as proteinuria. Almost identical results were obtained in both rat strains. In contrary, SDZ RAD ameliorated significantly the development of PAN nephrosis. Animals pretreated by this agent showed a significant reduction of proteinuria and of glomerular invasion of monocytes/macrophages. CONCLUSION: Some caution is warranted for the use of SDZ RAD in inflammatory glomerular diseases, since it accentuated glomerular damage induced by anti-Thy1.1 antibodies.

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.

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.