Levels of UUO renal injury.

<p>(<b>A</b>) Representative microscopic images of CLK and UUO kidneys in WT, Skp2^−/−, Skp2^−/−p27^−/− and p27^−/− mice (Masson's trichrome staining; scale bars: 50 µm). Increases in the interstitial area, tubular dilatation and atrophy, and interstitial cell infiltration are observed in the UUO kidneys in WT mice. However, the severities of these lesions are markedly less in the UUO kidneys in Skp2<b>^−/−</b> mice. In contrast, aggravation of the UUO renal injury is noted in Skp2^−/−p27^−/− and p27^−/− mice. (<b>B</b>) The severity of fibrotic tubulointerstitial lesions was graded semiquantitatively as follows: 0, absent (0%); 1, weak (≤10%); 2, mild (>10 to ≤30%); 3, moderate (>30 to ≤50%); 4, strong (>50%) in WT, Skp2^−/−, Skp2^−/−p27^−/− and p27^−/− mice at 7 days after UUO. (<b>C–E</b>) The numbers of dilated tubules (<b>C</b>), renal tubular epithelial cells in a tubule (<b>D</b>), and tubular interstitial cells (<b>E</b>) were counted and evaluated statistically in the UUO kidneys in WT, Skp2^−/−, Skp2^−/−p27^−/− and p27^−/− mice at 7 days after UUO. The CLK kidneys in WT mice were evaluated as controls. *<i>P</i><0.05, **<i>P</i><0.01 versus WT CLK kidneys, ^#<i>P</i><0.05, ^##<i>P</i><0.01 versus WT UUO kidneys and ^†<i>P</i><0.05, ^††<i>P</i><0.01 versus Skp2^−/− UUO kidneys.