Although
ischemia remains the leading cause of
acute renal failure in humans, there is little information on the expression and activities of
gelatinases of kidney glomeruli during
ischemia-reperfusion injury. In this study, we used a unilateral
ischemia-reperfusion model to investigate the activity and expression of
gelatinases in glomeruli during acute
ischemia. Unilateral
ischemia was induced in rats by vascular clamping (30 min) followed by reperfusion (60 min) and isolation of glomeruli. The activity and expression of
gelatinase proteins were determined by
gelatin zymography and Western blotting.
Gelatinase mRNA levels were evaluated by
reverse transcriptase-PCR.
Ischemia and reperfusion increased serum
creatinine levels, hallmark of
acute renal failure.
Ischemia induced
mRNA and
protein MMP-2 expression. There was strong stimulation of MMP-9
mRNA, both forms of dimeric MMP-9, and active monomeric MMP-9. In contrast to
TIMP-1 decreasing,
TIMP-2 protein and
mRNA increased during
ischemia. During reperfusion, there was a gradual reversal of the MMP-2 and MMP-9 levels and a strong inhibition of
TIMP-1 and
TIMP-2 at the
protein and
mRNA levels. Endocytic receptor LRP was increased during
ischemia and returned to normal during reperfusion. Expression of MMP-9 docking receptor CD-44 was increased during reperfusion. Finally, ZO-1, an in vivo MMP-9 substrate, was degraded during
ischemia, revealing that MMP-9 upregulated during
ischemia was functional. Our data suggest that stimulation of
gelatinase activity during
ischemia could contribute to glomeruli injury, providing new therapeutic targets for
acute renal failure in humans. In contrast, elevated monomeric MMP-9 activity due to
TIMP-1 decrease during reperfusion may participate to glomerular recovery.