CD80, suPAR and nephrotic syndrome in a case of NPHS2 mutation.

BACKGROUND Podocin mutations are characterized by progression to end stage renal disease and histologic findings of Focal Segmental Glomerulosclerosis (FSGS). CD80 is a podocytes protein that may play a role in proteinuria, particularly in Minimal Change Disease whereas the soluble urokinase receptor (suPAR) is characteristically elevated in the serum of FSGS patients. METHODS In a patient with nephrotic syndrome and podocin mutation, urinary and serum CD80 as well as suPAR were measured using commercially available kits. Urinary CD80 molecular size was determined by western blot analysis. Glomerular staining for CD80 and podocin was performed. RESULTS Patient displayed marked elevated CD80 and mildly increased suPAR urinary levels compared to controls. Serum CD80 level was within the range observed in normal controls. Serum suPAR level was elevated, albeit in the lower range reported for patients with primary FSGS. Immunofluorescence examination of kidney biopsy revealed glomerular CD80 expression. CONCLUSION The combination of serum and urinary biomarkers can help differentiate various forms of FSGS. High urinary CD80 and elevated serum and urinary suPAR might represent a profile to differentiate this genetic form of FSGS from primary FSGS.