Urinary proteome analysis and the management of ureteropelvic junction obstruction

Current status and future directions of application of urine proteomics in neonatology

With continuous advancements in mass spectrometry technology, researchers increasingly utilize this method to investigate the molecular mechanisms underlying various diseases, and to identify novel diagnostic and therapeutic strategies. Among proteomics applications, urinary proteomics stands out for its non-invasive nature, making it particularly suitable for vulnerable populations like neonates. This review provides a comprehensive overview of recent research on urinary proteomics in the field of neonatology. It summarizes findings from numerous studies, illustrating how urinary proteomic profiles provide critical insights into neonatal health and disease. By identifying specific protein biomarkers in urine, researchers can gain insights into the early detection and monitoring of neonatal diseases, potentially leading to more timely and effective interventions. As technology evolves, the sensitivity and accuracy of proteomic analyses are expected to improve, opening new avenues for research and clinical applications.

Urinary proteome analysis to exclude severe vesicoureteral reflux

OBJECTIVES

High-grade vesicoureteral reflux (VUR, grade IV or V) is a risk factor for renal scarring, impaired renal function, and arterial hypertension. Voiding cystourethrography is the gold standard for detecting the severity of VUR. High-grade VUR is present in the minority of children with urinary tract infection (UTI), thus exposing the majority to invasive diagnostics that have no surgical consequence. We therefore aimed at establishing a noninvasive test to identify children with high-grade VUR.

METHODS

In a case-control study, a specific urinary proteome pattern was established by capillary electrophoresis coupled to mass spectrometry in 18 patients with primary VUR grade IV or V, distinguishing these from 19 patients without VUR after UTI. This proteome pattern was independently validated in a blinded cohort of 17 patients with VUR grade IV or V and 19 patients without VUR.

RESULTS

Sensitivity in detecting VUR grade IV or V in the blinded study was 88%, specificity was 79%. The test's accuracy was independent of age, gender, and grade of VUR in the contralateral kidney. The odds ratio of suffering from VUR grade IV or V when tested positive was 28 (95% confidence interval: 4.5 to 176.0).

CONCLUSIONS

This noninvasive test is ready for prospective validation in large cohorts with the aim of identifying those children with UTI and hydronephrosis in need of further invasive diagnostics, such as voiding cystourethrography, thus sparing most children without pathologic urinary proteome patterns from additional diagnostics.

Urinary metabolomics in newborns and infants

Metabolomics is a new approach based on the systematic study of the full complement of metabolites in a biological sample. This technology consists of two sequential steps: (1) an experimental technique, based on nuclear magnetic resonance (NMR) spectroscopy or mass spectrometry, designed to profile low-molecular-weight compounds, and (2) multivariate data analysis. The metabolomic analysis of biofluids or tissues has been successfully used in the fields of physiology, diagnostics, functional genomics, pharmacology, toxicology, and nutrition. Recent studies have evaluated how physiological variables or pathological conditions can affect metabolomic profiles of different biofluids in pediatric populations. The overall metabolic status of the neonate is little known. If more information on perinatal/neonatal maturational processes and their metabolic background were available, the management of sick or preterm newborns might be improved. Currently, the use of metabolomics in neonatology is still in the pioneering phase. Meaningful diagnostic information and simple, noninvasive collection techniques make urine a particularly suitable biofluid for metabolomic approach in neonatal medicine, although blood has also been investigated. Different fields of neonatology such as postnatal maturation, asphyxia/hypoxia, inborn errors of metabolism, nutrition, nephrouropathies, nephrotoxicity, cardiovascular diseases, and other conditions have been investigated using a metabolomic approach. Together with genomics and proteomics, metabolomics appears to be a promising tool in neonatology for the monitoring of postnatal metabolic maturation, the identification of biomarkers as early predictors of outcome, the diagnosis and monitoring of various diseases, and the "tailored" management of neonatal disorders.

Urinary levels of TGF β-1 and of cytokines in patients with prenatally detected nephrouropathies

This study aimed to identify noninvasive biomarkers of clinically significant nephrouropathies in patients with antenatal renal and/or urinary tract alterations. Spot-urine levels of interleukin-6 (IL-6), transforming growth factor-β1 (TGF-β1) and tumor necrosis factor-α (TNF-α) were measured in 100 patients with antenatal detected nephrouropathies. Patients were divided in idiopathic hydronephrosis (n = 47), urinary tract malformations (n  = 35), and dysplastic kidneys (n = 18). Urinary concentrations of TGF-β1, IL-6, and TNF-α were compared between groups according to clinical and image findings. Receiver-operating characteristic (ROC) curves were analyzed for the overall diagnostic accuracy of TGF-β1, IL-6, and TNF-α levels in discriminating infants with nephrouropathies. No significant differences in urinary TGF- β1, IL-6, and TNF-α levels were found in the comparison between the groups. TGF-β1 levels tended to be higher in patients with renal hypodysplasia compared to idiopathic hydronephrosis (p = 0.07). Twenty-nine patients had reduced DMSA uptake. In these cases, absolute urinary concentration of TGF-β1 and levels standardized for creatinine were significantly higher than in patients with normal DMSA uptake, while IL6 and TNF-α did not differ between groups. Urinary cytokine measurements were not useful as a screening test for clinically significant nephrouropathies. Conversely, increased concentrations of TGF-β1 pointed out to renal damage as indicated by reduced DMSA uptake.