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Am J Physiol Renal Physiol. 2008 Apr;294(4):F739-47. doi: 10.1152/ajprenal.00508.2007. Epub 2008 Jan 23.

Netrin-1 and kidney injury. I. Netrin-1 protects against ischemia-reperfusion injury of the kidney.

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  • 1Division of Nephrology, H040, Pennsylvania State Univ. College of Medicine, 500 Univ. Drive, Hershey, PA 17033, USA.

Abstract

Endogenous mechanisms exist to limit inflammation. One such molecule is netrin. This study examined the impact of ischemia-reperfusion (I/R) on netrin expression and the role of netrin in preventing renal inflammation and injury. All three isoforms of netrin (1, 3, and 4) are expressed in normal kidney. I/R significantly downregulated netrin-1 and -4 mRNA expression, whereas expression of netrin-3 was moderately upregulated at 24 h of reperfusion. The netrin receptor UNC5B mRNA increased at 3 h and but decreased at later time points. Expression of a second netrin receptor, DCC, was not altered significantly. I/R was associated with dramatic changes in netrin-1 protein abundance and localization. Netrin-1 protein levels increased between 3 and 24 h after reperfusion. Immunolocalization showed an interstitial distribution of netrin-1 in sham-operated kidneys which colocalized with Von Willebrand Factor suggesting the presence of netrin-1 in peritubular capillaries. After I/R, interstitial netrin-1 expression decreased and netrin-1 appeared in tubular epithelial cells. By 72 h after reperfusion, netrin-1 reappeared in the interstitium while tubular epithelial staining decreased significantly. Downregulation of netrin-1 in the interstitium corresponded with increased MCP-1 and IL-6 expression and infiltration of leukocytes into the reperfused kidney. Administration of recombinant netrin-1 significantly improved kidney function (blood urea nitrogen: 161 +/- 7 vs. 104 +/- 24 mg/dl, creatinine: 1.3 +/- 0.07 vs. 0.75 +/- 0.16 mg/dl, P < 0.05 at 24 h) and reduced tubular damage and leukocyte infiltration in the outer medulla. These results suggest that downregulation of netrin-1 in vascular endothelial cells may promote endothelial cell activation and infiltration of leukocytes into the kidney thereby enhancing tubular injury.

PMID:
18216145
[PubMed - indexed for MEDLINE]
PMCID:
PMC3713074
Free PMC Article
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