Quali-quantitative analysis of urinary glycosaminoglycans for monitoring glomerular inflammatory activity

A 2-year follow-up study was carried out in patients with IgA nephropathy (IgAN) in order to verify the possible use of quali-quantitative analysis of urinary glycosaminoglycans (GAGs) as a prognostic index of disease and for drug treatment monitoring.

Ten patients with IgAN were evaluated at four time points: baseline, and 6, 9 and 24 months later. GAGs were isolated from 24-h urine using ion-exchange chromatography on diethylaminoethyl-Sephacel, and concentrations were expressed as milligrams of hexuronate per gram of creatinine. GAG composition was determined by cellulose acetate electrophoresis and expressed as relative percentages by means of densitometric scanning of Alcian Blue-stained strips.

The relative content of total low-sulphated chondroitin sulphate species decreased significantly during the study period compared to baseline, whereas the relative percentages of heparan sulphate and chondroitin sulphate increased significantly. Moreover, a significant correlation was noted between the relative contents of urinary GAGs, renal function and inflammation indexes.

It is likely that the excretion of various types of GAGs may be related to different glomerular pathophysiological conditions. Therefore, the determination of urinary GAG composition may represent a reliable indicator of disease activity.