Cystinuria is a purely renal rare genetic disease caused by mutations in cystine transporter genes and characterized by defective cystine reabsorption leading to kidney stones. In 14% of cases patients undergo nephrectomy, but given the difficulty to predict the evolution of the disease, the identification of markers of kidney damage would improve the follow up of patients with a higher risk.
The aim of the present study is to develop a robust, reproducible and non-invasive methodology for proteomic analysis of urinary exosomes using high resolution mass spectrometry. A clinical pilot study, conducted on 8 cystinuria patients vs. 10 controls, highlighted 165 proteins, of which 38 were up-regulated, that separate cystinuria patients from controls, and further discriminate between severe and moderate forms of the disease. These proteins include markers of kidney injury, circulating proteins and a neutrophil signature. Analysis of selected proteins by immunobloting, performed on six additional cystinuria patients, validated the mass spectrometry data.
This is the first successful proteomic study in cystinuria unmasking potential role of inflammation in this disease. The workflow we have developed is applicable to investigate urinary exosomes in different renal diseases and to search for diagnostic/prognostic markers. Data are available via ProteomeXchange with identifier PXD001430.