High glucose modifies heparansulphate synthesis by mouse glomerular epithelial cells

Background Alterations in:proteoglycan metabolism are involved in the patho genesis of diabetic nephropathy. The aim of this study is to evaluate the e ffects of high glucose on proteoglycan production and to find a reliable in vitro model for the study of diabetic nephropathy. Methods A clone of mouse glomerular epithelial cells was cultured in media containing elevated (30 mmol) and physiological (5 mmol) glucose, or iso-os molar (30 mmol) mannitol concentrations. We: evaluated the synthesis of (SO 4)-S-35-labeled molecules and the amount of proteoglycans by Sepharose CL6B and DEAE-Sephacel chromatographies. Results A clear decrease (56%) in total cell-layer proteoglycan synthesis w as induced by 30 mmol glucose, in comparison with normal glucose. A reducti on of 25% in medium associated proteoglycan synthesis was observed in high glucose cultured cells. After Sepharose CL6B, in cells cultured in high glu cose, cell layer heparansulphate proteoglycan-I (Kav 6B 0.04) synthesis was reduced by about 81%, heparansulphate proteoglycan-II (Kav 6B 0.21) by abo ut 87% and heparansulphate glycosaminoglycan (Kav 0.4-0.8) by about 91%, re spectively. In mannitol-incubated cells the reductions observed were less e vident and not significantly different from those in normal glucose. Conclusions These results indicate that (1) glomerular epithelial cells pla y a central role in proteoglycan synthesis, (2) high glucose modifies the a mount and influences the different species production of these macromolecul es, while osmotic forces seem to be only partially involved in these effect s, and (3) this cellular clone of glomerular epithelial cells can represent a reliable in vitro model for the study of the mechanisms involved in diab etic nephropathy. Copyright (C) 1999 John Wiley & Sons, Ltd.