Composition and inhibitory properties of endogenous urinary GAGS are different in subjects from two race groups with different occurrence rates of kidney stones: Pilot studies provide unique evidence in support of an inhibitory role for this group of compounds

• Published in: Clinica chimica acta 2022-01, Vol.525, p.84-90
• Main Authors: Jappie, Dalielah, Rodgers, Allen, Ravenscroft, Neil, Webber, Dawn, Gohel, Mayur Danny I.
• Format: Article
• Language: English
• Subjects: Calcium Oxalate; Crystallization; Crystallization inhibitors; Glycosaminoglycans; Humans; Inter-race differences; Kidney Calculi; Kidney stones; Pilot Projects; Urinary Calculi; Urinary glycosaminoglycans
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/j.cca.2021.11.030

•Inter-race comparison of concentration and composition of endogenous GAGS: 1st study.•Inter-race comparison of urinary crystal inhibition by endogenous GAGs: 1st study.•Concentration of chondroitin sulfate in GAGS: black subjects (B) > white subjects (W).•Inhibitory effect on calcium oxalate crystallization: GAGS from B > GAGS from W.•Stronger inhibitory effect attributed to higher chondroitin sulfate in GAGS from B. Calcium oxalate (CaOx) kidney stone disease is common in South African whites (W) but is rare in the black population (B). The possible role of endogenous urinary glycosaminoglycans (GAGs) has not been previously investigated in this context. To determine concentration, composition, structure and CaOx crystal-inhibiting properties of this group of compounds in ultrafiltered urine of healthy subjects from both groups. GAGS were isolated from 24 h urine samples and were quantified and characterized by sequential precipitation, Bradford protein assay, high performance liquid chromatography, and anion exchange high performance chromatography. CaOx crystal inhibition was determined in ultrafiltered urinary fractions to which purified GAGS (PG) from each group (PGB and PGW) had been added. Nucleation, growth and aggregation were measured by Coulter particle counting, spectrophotometric assay and [14C]-oxalate deposition. Higher concentrations of chondroitin sulfate (CS) were found in PGB than in PGW. PGB inhibited crystallization to a greater extent than PGW. We attribute the stronger inhibitory effect of PGB to its higher content of CS and suggest that the superior inhibition of CaOx crystallization by PGB relative to PGW might be a contributory factor in accounting for the lower stone occurrence rate in B.