Glomerular mRNAs in human type 1 diabetes: biochemical evidence for microalbuminuria as a manifestation of diabetic nephropathy.
BACKGROUND
In patients with type 1 diabetes, some consider microalbuminuria to be a predictor of diabetic nephropathy while others believe it is an early feature of diabetic nephropathy.


METHODS
Levels of mRNAs that are of pathogenetic relevance in diabetic nephropathy were compared in glomeruli isolated from microalbuminuric and overtly proteinuric subjects and in control normoalbuminuric diabetic subjects and living renal transplant donors.


RESULTS
In subjects with microalbuminuria and overt proteinuria, glomerular mRNAs were virtually identical and approximately twofold higher for connective tissue growth factor (CTGF; P < 0.01) and collagen alpha2(IV) (P < 0.03) compared to living renal donors and normoalbuminuric patients. Glomerular glyceraldehyde-3-phosphate dehydrogenase (GAPDH) levels were not significantly different among the groups (P = 0.4). Weak but statistically significant correlations were noted between CTGF mRNA and albuminuria (assessed by rank), fractional mesangial surface area, and a composite renal biopsy index. Glomerular CTGF mRNA correlated inversely with creatinine clearance. Glomerular collagen alpha2(IV) mRNA levels correlated with albuminuria (by rank) and less strongly with fractional mesangial area.


CONCLUSIONS
To our knowledge, these data provide the first biochemical evidence demonstrating that the glomeruli of microalbuminuric patients and those with overt proteinuria do not differ significantly. The data support the concept that microalbuminuria is not "predictive" of diabetic nephropathy, but rather is an earlier point in the spectrum of diabetic nephropathy.
Adler
S G
SG
Division of Nephrology and Hypertension, Harbor-UCLA Research and Education Institute, Torrance, CA 90502, USA. sadler@rei.edu
Kang
S W
SW
Feld
S
S
Cha
D R
DR
Barba
L
L
Striker
L
L
Striker
G
G
Riser
B L
BL
LaPage
J
J
Nast
C C
CC
D000328:Adult; D000419:Albuminuria / Q000378:metabolism* / Q000473:pathology; D001706:Biopsy; D024141:Collagen Type IV / Q000235:genetics*; D055513:Connective Tissue Growth Factor; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism*; D003928:Diabetic Nephropathies / Q000378:metabolism* / Q000473:pathology; D006133:Growth Substances / Q000235:genetics*; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics*; D036341:Intercellular Signaling Peptides and Proteins; D007678:Kidney Glomerulus / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D011507:Proteinuria / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
C526317:CCN2 protein, human; D024141:Collagen Type IV; D006133:Growth Substances; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D055513:Connective Tissue Growth Factor