Functional and molecular alterations of the glomerular barrier in long-term diabetes in mice.
OBJECTIVE
Despite the fact that diabetic nephropathy is an increasingly common disorder that may lead to uraemia, the underlying mechanisms are still poorly understood and there is no specific therapy. To clarify whether long-term diabetes alters glomerular size- or charge-selectivity or both, we studied non-obese diabetic mice for up to 40 weeks.


METHODS
During the study period, spot urine was collected and blood pressure measured. At weeks 10 and 40, the right kidney was isolated and perfused at 8 degrees C to inhibit tubular function, allowing for analysis of glomerular selectivity with albumin and Ficoll clearance. The left kidney was removed for further investigation using electron microscopy and molecular biology. Real-time PCR with low-density arrays was done to evaluate renal cortex mRNA expression of proteoglycans and other components in the glomerular barrier. After 40 weeks of diabetes, kidneys showed morphological changes typical of diabetic complications.


RESULTS
At 40 weeks, the fractional clearance for negatively charged albumin was three times higher in the diabetic animals (0.0160) than in controls (0.0051, p<0.001), while fractional clearance for neutral Ficoll 35.5 A with a Stokes Einstein radius similar to that of albumin was unaffected. In addition, protein and mRNA levels for versican and decorin were downregulated after 40 weeks of diabetes.


CONCLUSIONS
We conclude that glomerular charge- but not size-selectivity was impaired in the diabetic animals with proteinuria. Also, glomerular components such as versican, decorin and fibromodulin were found to be downregulated after 40 weeks of diabetes.
Jeansson
M
M
Renal Center, Department of Nephrology, Institute of Internal Medicine, Sahlgrenska Academy, Bruna Straket 16, SE-413 45, Gothenburg, Sweden. marie.jeansson@kidney.med.gu.se
Granqvist
A Björnson
AB
Nyström
J Sörensson
JS
Haraldsson
B
B
D000418:Albumins / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure; D015153:Blotting, Western; D001835:Body Weight; D003401:Creatine / Q000652:urine; D058575:Decorin; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology*; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D000071235:Fibromodulin; D015870:Gene Expression; D005919:Glomerular Filtration Rate; D007678:Kidney Glomerulus / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D016688:Mice, Inbred NOD; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D053675:Versicans / Q000235:genetics / Q000378:metabolism
D000418:Albumins; C546879:Dcn protein, mouse; D058575:Decorin; D016326:Extracellular Matrix Proteins; C000604332:Fmod protein, mouse; D011509:Proteoglycans; D012333:RNA, Messenger; D000071235:Fibromodulin; D053675:Versicans; D003401:Creatine