Serum and urinary concentrations of heparan sulfate in patients with diabetic nephropathy

Abstract

Background. Heparan sulfate (HS) contributes to the negative charge in the glomerular basement membrane (GBM), which may maintain the GBM charge barrier. Changes in sulfation and/or the concentration of HS may be associated with the development of diabetic nephropathy. Methods. Using two different antibodies specific for HS chains, one that reacts with the N- sulfated sequences in HS chains (10E4) and the other that reacts with neo- epitope of HS, which occurs after heparitinase digestion of HS chains (3G10), we examined the serum and urinary concentrations of HS by enzyme-linked immunosorbent assay and performed immunohistochemical staining of glomeruli in diabetic patients with and without nephropathy. Results. The level of urinary excretion of 10E4 binding HS/creatinine clearance was significantly reduced in diabetic patients when compared with that in nondiabetic subjects (P < 0.0001), and the level was more decreased in patients with overt nephropathy than in patients without overt nephropathy. No differences or only small differences were found between these groups in serum and urinary 3G10-binding HS and in serum 10E4-binding HS. Immunohistochemical staining with these antibodies was consistent with the findings in the urine. Conclusions. The results suggest that a decreased HS N-sulfation exists in the urine, which may reflect a structural change or an altered processing of HS within the GBM. Because N-sulfation plays a key role in determining the extent of sulfation within the HS chains, the decreased urinary 10E4-binding HS may have potential implications with regard to the development of diabetic nephropathy.