Detergent-resistant globotriaosyl ceramide may define verotoxin/glomeruli-restricted hemolytic uremic syndrome pathology

Verotoxin binding to its receptor, globotriaosyl ceramide(Gb3) mediates the glomerular pathology of hemolytic uremic syndrome, but Gb3 is expressed in both tubular and glomerular cells. Gb3 within detergent-resistant membranes, an index of glycolipid-cholesterol enriched lipid rafts, is required for in vitro cytotoxicity. We found that verotoxin 1 and 2 binding to human adult renal glomeruli is detergent resistant, whereas the strong verotoxin binding to renal tubules is detergent sensitive. Verotoxin binding to pediatric glomeruli was detergent resistant but binding to adult glomeruli was enhanced, remarkably for some samples, by detergent extraction. Detergent-sensitive glomerular components may provide age-related protection against verotoxin glomerular binding. Mouse glomeruli remained verotoxin unreactive after detergent extraction, whereas tubular binding was lost. Cholesterol extraction induced strong verotoxin binding in poorly reactive adult glomeruli, suggesting cholesterol can mask Gb3 in glomerular lipid rafts. Binding of the human immunodeficiency virus (HIV) adhesin, gp120 (another Gb3 ligand) was detergent sensitive, tubule-restricted, and inhibited by verotoxin B subunit pretreatment, and may relate to HIV nephropathy. Our study shows that differential membrane Gb3 organization in glomeruli and tubules provides a basis for the age- and glomerular-restricted pathology of hemolytic uremic syndrome.