Immune Dysfunction in Neonatal Ureteral Obstruction

Douglas Mark Silverstein, MD, Principal Investigator
Research Associate

Abstract
Severe congenital obstructive uropathy (COU) is one of the most common causes of chronic renal failure in children, resulting in severe and progressive renal parenchymal damage. Neonatal rat unilateral ureteral obstruction (UUO) is a model of severe COU. Early after neonatal UUO the kidney is flooded with lymphocytes and macrophages. Even after relief of chronic neonatal UUO, the kidney exhibits inflammation and interstitial fibrosis. The causes of the ongoing inflammation and fibrosis remain unclear. In the post-obstructed kidney, the number of glomeruliis reduced by 40%, and GFR is decreased by 80%. Studies done in our laboratory reveal that there is abnormal expression of several immune modulatory genes, including krox24, MCP-1, IRF-1 and JunD in chronic neonatal UUO. We speculate that these genes cause interstitial inflammation and fibrosis and contribute to progressive damage in neonatal UUO. SPECIFIC AIMS: In Neonatal UUO: 1) SPECIFICITY OF IMMUNE MODULATOR GENE CHANGES. To determine how specific the changes are to neonatal UUO, we will compare the changes in that condition to adult UUO and congenital mild hydronephrosis by performing real-time RT-PCR and western blot analysis. 2) TIME-RELATED CHANGES IN IMMUNE MODULATOR GENE EXPRESSION. To assess changes in mRNA expression and protein abundance, we will perform real-time RT-PCRand western blot analysis on Day 0 (pre) and on Days 4, 8, 12 and 30 after obstruction on sham-operated and obstructed kidneys. 3) REGIONS OF THE KIDNEY IN WHICH THE IMMUNE GENES ARE EXPRESSED. To determine the regions of the kidney in which these genes are expressed, we will perform immunohistochemistry. We will assess their co-localization with TGF-beta and renin, both up-regulated in UUO. We will also assess their co-localization with markers of macrophage infiltration (ED-!) and collagen deposition (Collagen 1 and 4). 4) RELATIONSHIP OF THE IMMUNE GENES TO OTHER GENES. To elucidate the pathways inducing immune modulator gene expression or stimulated as a result of these genes, we will use microarray analysis to compare gene expression in neonatal UUO versus adult UUO and mild congenital hydronephrosis.

Collaborations
Robert L. Chevalier, University of Virginia
Howard A Trachtman, Long Island Jewish Medical Center
Frankin G. Boineau, Tulane University Medical Center

Sponsor: NIH
Duration: 1/04 - 12/05