Aim: To assess the relation between urinary excretion of profibrotic and antifibrotic growth factors, albuminuria and glomerular fibrosis in type 1 diabetic patients.
Materials and methods: 64 patients with diabetes were examined, including 25 ones with normal albumin excretion rate (AER), 30 microalbuminuric and 9 macroalbuminuric patients. Urinary excretion of type IV collagen, transforming growth factor-beta 1] (TGF-beta 1), tumor necrosis factor-alpha (TNF-alpha), fibroblast growth factor-2 (FGF-2), hepatocyte growth factor (HGF) and bone morphogenetic protein-7 (BMP-7) was determined by ELISA and compared to control (10 healthy subjects). Renal biopsy specimens were assessed in 7 patients with normal AER and in 14 microalbuminuric patients.
Results: Type IV collagen, TGF-beta1 and TNF-alpha excretion was increased significantly in patients with micro- and macroalbuminuria as compared to control (all p<0.05). Excretion of FGF-2 was increased in macroalbuminuric patients only (p=0.003). No marked changes in excretion of antifibrotic growth factors (HGF and BMP-7) were observed. TNF-alpha and FGF-2 correlated positively with urinary type IV collagen (r=0.37 and r=0.31, respectively). The presence of glomerular fibrosis in renal biopsy specimens was associated with higher excretion of TGF-beta1, TNF-alpha and FGF-2 (all p<0.05).
Conclusion: The results suggest that unbalance between profibrotic and antifibrotic growth factors in the kidneys plays an important role in pathogenesis of diabetic nephropathy. Urinary TGF-beta1, TNF-alpha and FGF-2 may offer new possibilities for detection of renal fibrosis in diabetic patients.