Vascular proliferation and enhanced expression of endothelial nitric oxide synthase in human peritoneum exposed to long-term peritoneal dialysis.
Long-term peritoneal dialysis (PD) is associated with alterations in peritoneal permeability and loss of ultrafiltration. These changes originate from increased peritoneal surface area, but the morphologic and molecular mechanisms involved remain unknown. The hypothesis that modifications of activity and/or expression of nitric oxide synthase (NOS) isozymes might play a role in these modifications, via enhanced local production of nitric oxide, was tested in this study. NOS activities were measured by the L-citrulline assay in peritoneal biopsies from seven control subjects, eight uremic patients immediately before the onset of PD, and 13 uremic patients on short-term (<18 mo, n = 6) or long-term(>18 mo, n = 7) PD. Peritoneal NOS activity is increased fivefold in long-term PD patients compared with control subjects. In uremic patients, NOS activity is positively correlated with the duration of PD. Increased NOS activity is mediated solely by Ca(2+)-dependent NOS and, as shown by immunoblotting, an upregulation of endothelial NOS. The biologic relevance of increased NOS in long-term PD was demonstrated by enhanced nitrotyrosine immunoreactivity and a significant increase in vascular density and endothelial area in the peritoneum. Immunoblotting and immunostaining studies demonstrated an upregulation of vascular endothelial growth factor (VEGF) mostly along the endothelium lining peritoneal blood vessels in long-term PD patients. In the latter, VEGF colocalized with the advanced glycation end product pentosidine deposits. These data provide a morphologic (angiogenesis and increased endothelial area) and molecular (enhanced NOS activity and endothelial NOS upregulation) basis for explaining the permeability changes observed in long-term PD. They also support the implication of local advanced glycation end product deposits and liberation of VEGF in that process.
Combet
Sophie
S
Division of Nephrology, Université Catholique de Louvain Medical School, Brussels, Belgium.|Division of Cell Biology, Commissariat à l'Energie Atomique, Saclay, France.
Miyata
Toshio
T
Institute of Medical Science and Department of Internal Medicine, Tokai University School of Medicine, Kanagawa, Japan.
Moulin
Pierre
P
Department of Pathology, Université Catholique de Louvain Medical School, Brussels, Belgium.
Pouthier
Dominique
D
Division of Nephrology, Centre Hospitalier de Luxembourg, Luxembourg.
Goffin
Eric
E
Division of Nephrology, Université Catholique de Louvain Medical School, Brussels, Belgium.
Devuyst
Olivier
O
Division of Nephrology, Université Catholique de Louvain Medical School, Brussels, Belgium.
D000328:Adult; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D001808:Blood Vessels / Q000378:metabolism / Q000473:pathology; D016228:Endothelial Growth Factors / Q000378:metabolism; D005169:Factor VIII / Q000378:metabolism; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D008222:Lymphokines / Q000378:metabolism; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010530:Peritoneal Dialysis; D010537:Peritoneum / Q000098:blood supply* / Q000201:enzymology*; D012016:Reference Values; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D007527:Isoenzymes; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D005169:Factor VIII; D001120:Arginine; C062187:pentosidine; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D008239:Lysine