The role of β-2-microglobulin and cystatin C as urinary biomarkers of focal segmental glomerulosclerosis in the setting of paediatric HIV infection

BACKGROUND. Africa has the highest rate of HIV infection, and HIV-associated nephropathy (HIVAN) is one of the most frequent kidney diseases observed in children. HIVAN in children usually presents as a form of nephrotic syndrome, predominantly focal segmental glomerulosclerosis (FSGS) on histopathology, that often leads to chronic kidney failure. OBJECTIVE. This study determined the urinary concentrations of β-2-microglobulin (β2M) and cystatin C proteins in children with HIVAN and primary FSGS. METHODS. The study group comprised 34 children; 14 with HIVAN and 20 with primary FSGS. The control groups were 20 HIV-positive and 20 HIV-negative children with no kidney disease. Urine samples collected from these 74 children were stored at -80°C. Bio-Plex technology was used to analyse the urinary protein concentration of cystatin C and β2M. RESULTS. A significant increase in urinary β2M levels was observed in the HIVAN group compared with the HIV-negative group (p=0.0240). No other statistically significant differences in urinary β2M concentrations were noted across the study groups. Urinary cystatin C levels were significantly increased in primary FSGS children compared with both HIV-negative (p=0.0041) and HIV-positive controls (p=0.0256). Urinary cystatin C displayed a significant increase in the primary FSGS compared with the HIVAN group (p=0.0150). No significant differences in urinary cystatin C levels were noted in the HIVAN group compared with the HIV-negative and HIV-positive control groups. CONCLUSION. Urinary cystatin C has promising prognostic value to predict primary FSGS from HIVAN.