Urinary glycosaminoglycans in patients with systemic lupus erythematosus

Objective Several investigations indicate that glycosaminoglycans (GAG) are important components of the glomerular basement membrane (GBM) and that they play a remarkable role in the control of charge-selectivity; in the glomerular cap illary wall. In order to evaluate the possible use of GAG as a marker of gl omerular disease, we evaluated urinary GAG excretion in 37 patients with sy stemic lupus erythematosus (SLE) grouped by disease activity and kidney inv olvement and in 17 healthy controls. Methods GAG were isolated from urine by using ion-exchange chromatograph: on DEAE S ephacel. G;le composition uas determined by cellulose acetate electrophores is and expressed as relative percentages by densitometric scanning of Alcia n Blue stained strips. Results Total GAG levels were significantly increased only in active extra-renal SL E patients. Qualitative analysis of urinary GAG revealed the presence of a lost sulphated chondroitin sulphate-protein complex (LSC-PG), whose frequen cy was higher in patients compared to controls. Moreover inactive SLE was c haracterized by an alteration of the chondroitin sulphate/heparan sulphate ratio. Conclusion These variations suggest the presence of an abnormal permeability of the re nal filter in patients without other appreciable signs of kidney alteration . Therefore, qualitative-quantitative urinary GAG analysis could represent an additional diagnostic approach.