Concentration of selected low molecular-weight proteins in urine – a retrospective analysis of chronic kidney disease among HIV patients receiving antiretroviral therapy

Introduction
Human immunodeficiency virus (HIV) infection remains an important health problem despite the fact that combined antiretroviral therapy (cART) prolongs life and protects against acquired immunodeficiency syndrome (AIDS). Chronic kidney disease is an important cause of mortality among HIV patients, co-monitoring of renal function and modifying factors such as cART require constant analysis. The aim of this study was a retrospective analysis of renal function among HIV- infected and cART-treated patients by measuring urine concentrations of chosen low molecular weight proteins (LMWP) as biomarkers of kidney dysfunction: retinol-binding protein (RBP), β2-microglobulin (β2M), and neutrophil gelatinase-associated lipocalin (NGAL). The results were compared with those obtained seven years earlier (in 2011) in the same patients.

Material and methods
Urine samples from 34 patients of Wroclaw outpatient HIV Clinic and from 30 HIV-negative individuals with no renal or any other disease were examined. Concentrations of LMWP were measured by immunoenzymatic ELISA tests.

Results
Compared to 2011, reduction in the concentration of excreted LMWP was observed. No deleterious renal effect of tenofovir could be shown; however, most patients were receiving the new prodrug (TAF) of reduced nephrotoxicity. Positive correlation between serum creatinine and urine β2M was shown and negative correlation between eGFR and urine RBP. Coexistence of HCV infection and the number of T CD4(+) cells also correlated with the concentration of the biomarkers.

Conclusions
This retrospective analysis shows a need for long-term renal function monitoring as well as other factors that may influence renal function among HIV patients. RBP, NGAL, and β2M have been confirmed to be useful biomarkers for early detection of renal dysfunction.