Although
ischemia is the leading cause of
acute renal failure in human, there is little information on the remodeling the kidney endothelium matrix during ischemic injury. In this study, we investigated the activity and expression of MMP-2 and MMP-9, in an isolated endothelial fraction following an acute in vivo reversible
ischemia induced in rats by vascular clamping.
Ischemia increased serum
creatinine levels 1.4-fold, hallmark of
acute renal failure. Isolation of the endothelial cell fraction was performed by affinity chromatography using an anti-PECAM-1 antibody. The isolated fraction was assessed by Western blotting analysis of endothelial cell markers. The positively selected fractions were enriched in the endothelial markers eNOS and
PECAM-1 by 128-fold and 44-fold, respectively.
Gelatin zymography showed that
ischemia strongly stimulated proteolytic activity of
proMMP-2 (1.8-fold),
proMMP-9 (3-fold) and MMP-9 (4-fold) in the endothelial fractions. Western blot analysis indicated that
TIMP-2 protein level increased by 3.2-fold in the endothelial fractions during
ischemia. Surprisingly,
TIMP-1 was absent from the endothelial preparations but was easily detected in the non-endothelial cells. Levels of the endocytic receptor LRP were increased by 2-fold during
ischemia in the endothelial fractions.
Occludin, a known in vivo MMP-9 substrate, was partly degraded in the endothelial fractions during
ischemia, suggesting that the MMP-9 which was upregulated during
ischemia was functional. These data suggest that
ischemia in kidney could lead to the degradation of the vascular basement membrane and to increased permeability. This suggests new therapeutic approaches for ischemic pathologies by targeting MMP-9 and its regulators.