Deterioration of glomerular endothelial surface layer induced by oxidative stress is implicated in altered permeability of macromolecules in Zucker fatty rats.
OBJECTIVE
The glomerular endothelial layer is coated by the endothelial surface layer (ESL), which is suggested to play a role in regulation of the permselectivity of macromolecules. Production of heparanase, a degrading enzyme of the ESL, is induced by reactive oxygen species (ROS). We hypothesised that oxidative stress could cause deterioration of the glomerular ESL by induction of heparanase, resulting in increased glomerular permeability.


METHODS
Male Zucker fatty (ZF) rats with albuminuria and Zucker lean (ZL) rats were used in this study. Some of the ZF rats were treated with the angiotensin II receptor blocker, irbesartan. We determined the amount of ESL by wheat germ agglutinin staining and heparan sulphate proteoglycan production by western blot analysis. Glomerular hyperfiltration of macromolecules was visualised using in vivo microscopy. We used 2',7'-dichlorofluorescein diacetate-derived chemiluminescence staining to assess ROS production, and heparanase production and expression were determined by western blot analysis and quantitative real-time polymerase chain reaction respectively.


RESULTS
By 18 weeks of age, ZF rats had developed albuminuria. The glomerular endothelial cell glycocalyx was significantly decreased in ZF compared with ZL rats. Glomerular filtration and the permeability of macromolecules were increased in ZF, but not in ZL rats. Glomerular ROS and heparanase production were significantly increased in ZF compared with ZL rats. These changes in ZF rats were reversed by irbesartan treatment.


CONCLUSIONS
Increased oxidative stress induces glomerular ESL deterioration in part through increased heparanase levels, resulting in exacerbation of glomerular permselectivity and development of albuminuria.
Kuwabara
A
A
Division of Nephrology and Hypertension, Department of Internal Medicine, Kawasaki Medical School, Kurashiki, Okayama, Japan.
Satoh
M
M
Tomita
N
N
Sasaki
T
T
Kashihara
N
N
D000419:Albuminuria / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000627:therapeutic use; D000818:Animals; D001713:Biphenyl Compounds / Q000627:therapeutic use; D015153:Blotting, Western; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D006439:Hemodynamics / Q000187:drug effects; D000077405:Irbesartan; D007678:Kidney Glomerulus / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011924:Rats, Zucker; D017382:Reactive Oxygen Species / Q000378:metabolism; D013777:Tetrazoles / Q000627:therapeutic use
D047228:Angiotensin II Type 1 Receptor Blockers; D001713:Biphenyl Compounds; D017382:Reactive Oxygen Species; D013777:Tetrazoles; D000077405:Irbesartan