Proteomic profile-based screening of potential protein biomarkers in the urine of patients with nephrotic syndrome

Abstract

Nephrotic syndrome is not a single disease; rather, it is a term for numerous diseases and pathological types. Renal biopsy is of use in determining the diagnosis and prognosis, and for guiding treatment; however, the use of this intervention is limited due to its invasive nature. Abnormal kidney‑derived proteins in the urine of patients provide useful information regarding numerous pathological processes that occur in the kidneys, and may be considered a potential non‑invasive biomarker for kidney disease. Proteomic analysis exhibits the advantage of being high‑throughput and has previously been used to identify biomarkers of disease. The present study aimed to identify abnormal kidney‑derived proteins in the urine of patients with nephrotic syndrome using a novel proteomic strategy. Urine samples from 5 patients with nephrotic syndrome were subjected to acetone precipitation and albumin/immunoglobulin G depletion prior to analysis by two‑dimensional liquid chromatography tandem mass spectrometry. The resulting data were compared to a publicly available proteomic database of normal human plasma/urine and normal human kidney in PeptideAtlas, and of normal human kidney in the Human Protein Atlas. Candidate biomarkers were validated using ELISA analysis in 60 patients with nephrotic syndrome: 30 with focal segmental glomerulosclerosis (FSGS) and 30 with minimal change disease (MCD), as well as in 30 healthy controls. The initial screening identified 809 proteins in the urine of patients with nephrotic syndrome. A total of 13/809 proteins were additionally present in the kidney proteome of PeptideAtlas and the Human Protein Atlas, although not in normal human urine and normal human plasma according to PeptideAtlas; these were referred to as 'kidney‑derived disease‑associated proteins'. One of the kidney‑derived disease‑associated proteins, ubiquitin‑60S ribosomal protein L40 (UBA52) was observed to be increased in the urine of patients compared with normal controls [Creatinine, 637 ng/mg (216‑1,851) vs. 1.89 ng/mg (1.37‑3.33), P<0.001; and 18.58 ng/mg (11.11‑46.25) vs. 1.89 ng/mg (1.37‑3.33), P<0.001)], and the urinary UBA52 levels were significantly increased in patients with FSGS compared with in patients with MCD (P<0.001). In conclusion, the present study identified potential novel urinary protein biomarkers for nephrotic syndrome, in addition to an extensive urinary proteomic profile of patients with nephrotic syndrome.

Urinary Protein and Peptide Markers in Chronic Kidney Disease

“…Several studies have aimed at identifying proteomic differences between these two nephropathies. In particular, it was shown that the calretinin and UBA52 levels were higher in FSGS [48,49], while the 39S ribosomal protein L17 was higher in MCD [48] (Table 2). Significantly higher levels of cathepsin B, cathepsin C, and annexin A3 were shown in cases of the collapsing variant of FSGS (characterized by glomerular collapse and a rapid loss of renal function) than in MCD, MN, and other FSGS variants [94].…”

The value of urinary RBP4 in the diagnosis of FSGS and other renal diseases

“…There is a number of studies comparing the pattern of urinary proteome of FSGS patients with the proteomic profiles of healthy controls and/or patients with other renal-diseases [5][6][7][8][9][10][11]. However, the past research have never confronted simultaneously the pattern of urinary proteome in FSGS patients with the proteomic profile of the normal status, IgA nephropathy (the second most common glomerulopathy worldwide) and the commonest subtypes of renal cancers i.e.…”

The Value of Urinary RBP4 in The Diagnosis of FSGS and other Renal Diseases.

“…There is a number of studies comparing the pattern of urinary proteome of FSGS patients with the proteomic pro les of healthy controls and/or patients with other renal-diseases [5,6,7,8,9,10,11]. However, the past research have never confronted simultaneously the pattern of urinary proteome in FSGS patients with the proteomic pro le of the normal status, IgA nephropathy (the second most common glomerulopathy worldwide) and the commonest subtypes of renal cancers i.e.…”