| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2003: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 2002: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
Rat remnant kidney is an established model of renal tubulointerstitial fibrosis and progression to end-stage renal failure. The morphologic lesions comprise nephron loss and regeneratory tubular hypertrophy, interstitial infiltration, predominately by macrophages, and progressive fibrosis. A critical role in this complex pathology was assigned to tubulointerstitial blood microvessels that regulate the supply of oxygen and nutrients of tubuli. Whereas some investigationsreported a rarefaction of the vascular network in association with the degenerative cortical changes, others observed an increase in vascularization. Here these discrepant findings are addressed by reinvestigation of the vascularization of rat remnant kidneys by the use of two novel endothelial lineage specific, discriminatorymarkers, i.e., the membrane mucoprotein podoplanin with specificity for lymphatic endothelia, and the glycosyl-phosphatidylinositol (GPI)-anchored membraneenzyme aminopeptidase P that is recognized
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by a monoclonal antibodydesignated JG12 and that is specifically expressed by endothelial cells of blood vessels only. The results obtained confirm a regional rarefaction of aminopeptidase P-positive blood microvessels ; they also establish major changes in the renal Iymphaticvasculature. Massiye proliferation of lymphatic vessels was observed in fibrotic tubulointerstitial regions, whereas in kidneys of sham-operated rats, only a fewlymphatic vessels were found adjoined with arteries. The lymphatic vessels frequently contained mononuclear cells that were also encountered in the interstitial spacesand expressed relative large amounts of vascular endothelial growth factor-C mRNA by in situ hybridization. Collectively, these results indicate that a large proportionof the microvessels encountered in the cortex of remnant kidneys are of lymphatic origin and cannot be discriminated by common endothelial markers, such as CD34, that are expressed by both lymphatic and blood endothelia cells. As lymphatic endothelial cells secrete chemokines that attract dendritic cells, it is possible that theincrease in lymphatic vascularization could enhance the immunologic surveillance of remnant kidneys. Less
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