Figure 8.

Inhibition of residual matrix metalloproteinases (MMP) activities in tissue inhibitor of MMP 3 (TIMP3)^−/−/TNFα^−/− mice further improves after unilateral ureteral obstruction (UUO) injury and fibrosis. (A) Gelatin zymography shows comparable levels of MMP9 and pro-MMP2, but reduced cleaved MMP2 in TIMP3^−/−/TNFα^−/−-UUO kidneys compared with TIMP3^−/−-UUO kidneys, although still higher than WT-UUO group. Averaged band densities for five zymograms are shown on the right. (B) TaqMan real-time PCR analysis of candidate MMPs shows significant reductions in expression of MMP7, MMP8, MMP9, and MMP12 in the TIMP3^−/−/TNFα^−/− compared with TIMP3^−/−-UUO. (C) Representative cross-sectional images of wild-type (WT), TIMP3^−/−, TIMP3^−/−/TNFα^−/−, and TIMP3^−/−/TNFα^−/− + MMPi (PD166793, a broad-spectrum MMP inhibitor) show a clear improvement in the medullary thickness in the last group. (D) Picrosirius red (PSR) staining and confocal imaging show that tubulointerstitial fibrosis is significantly improved in the double-knock out kidneys and completely blocked with additional MMP inhibition. Collagen-volume fraction (calculated on the basis of the PSR-stained section), production of collagen type I and α-SMA, and markers of fibrosis at 2wk post-UUO are significantly reduced in TIMP3^−/−/TNFα^−/− + MMPi compared with TIMP3^−/− kidneys. *P < 0.05 compared with sham-operated group; ‡P < 0.05 compared with corresponding WT group. †P < 0.05 compared with TIMP3^−/− group.