title: Proteomic-based research strategy identified laminin subunit alpha 2 as a potential urinary-specific biomarker for the medullary sponge kidney disease.
abstract: Medullary sponge kidney (MSK) disease, a rare kidney malformation featuring recurrent renal stones and nephrocalcinosis, continues to be diagnosed using expensive and time-consuming clinical/instrumental tests (mainly urography). Currently, no molecular diagnostic biomarkers are available. To identify such we employed a proteomic-based research strategy utilizing urine from 22 patients with MSK and 22 patients affected by idiopathic calcium nephrolithiasis (ICN) as controls. Notably, two patients with ICN presented cysts. In the discovery phase, the urine of 11 MSK and 10 controls, were randomly selected, processed, and analyzed by mass spectrometry. Subsequently, several statistical algorithms were undertaken to select the most discriminative proteins between the two study groups. ELISA, performed on the entire patients' cohort, was used to validate the proteomic results. After an initial statistical analysis, 249 and 396 proteins were identified exclusive for ICN and MSK, respectively. A Volcano plot and ROC analysis, performed to restrict the number of MSK-associated proteins, indicated that 328 and 44 proteins, respectively, were specific for MSK. Interestingly, 119 proteins were found to differentiate patients with cysts (all patients with MSK and the two ICN with renal cysts) from ICN without cysts. Eventually, 16 proteins were found to be common to three statistical methods with laminin subunit alpha 2 (LAMA-2) reaching the higher rank by a Support Vector Machine, a binary classification/prediction scheme. ELISA for LAMA-2 validated proteomic results. Thus, using high-throughput technology, our study identified a candidate MSK biomarker possibly employable in future for the early diagnosis of this disease.
authors.affiliation: Renal Unit, Department of Medicine, University Hospital of Verona, Verona, Italy.
authors.forename: Antonia
authors.initials: A
authors.lastname: Fabris
authors.affiliation: Laboratory on Physiopathology of Uremia, Istituto Giannina Gaslini, Genoa, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bruschi
authors.affiliation: Laboratory on Physiopathology of Uremia, Istituto Giannina Gaslini, Genoa, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Santucci
authors.affiliation: Laboratory on Physiopathology of Uremia, Istituto Giannina Gaslini, Genoa, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Candiano
authors.affiliation: Renal Unit, Department of Medicine, University Hospital of Verona, Verona, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Granata
authors.affiliation: Renal Unit, Department of Medicine, University Hospital of Verona, Verona, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Dalla Gassa
authors.affiliation: Renal Unit, Department of Medicine, University Hospital of Verona, Verona, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Antonucci
authors.affiliation: Laboratory of Mass Spectrometry, Core Facility, Istituto Giannina Gaslini, Genova, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Petretto
authors.affiliation: Division of Nephrology, Dialysis and Transplantation, Istituto Giannina Gaslini, Genoa, Italy.
authors.forename: Gian Marco
authors.initials: GM
authors.lastname: Ghiggeri
authors.affiliation: Division of Nephrology and Dialysis, Columbus-Gemelli University Hospital Catholic University, School of Medicine, Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gambaro
authors.affiliation: Renal Unit, Department of Medicine, University Hospital of Verona, Verona, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Lupo
authors.affiliation: Renal Unit, Department of Medicine, University Hospital of Verona, Verona, Italy. Electronic address: gianluigi.zaza@univr.it.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Zaza
mesh_terms: D000465:Algorithms; D019540:Area Under Curve; D015415:Biomarkers / Q000652:urine; D016022:Case-Control Studies; D016000:Cluster Analysis; D016002:Discriminant Analysis; D042241:Early Diagnosis; D004797:Enzyme-Linked Immunosorbent Assay; D057166:High-Throughput Screening Assays; D006801:Humans; D007797:Laminin / Q000652:urine*; D007691:Medullary Sponge Kidney / Q000175:diagnosis / Q000652:urine*; D011237:Predictive Value of Tests; D040901:Proteomics / Q000379:methods*; D012372:ROC Curve; D015203:Reproducibility of Results; D060388:Support Vector Machine; D053719:Tandem Mass Spectrometry; D016482:Urinalysis
chemical_list: D015415:Biomarkers; D007797:Laminin; C102645:laminin alpha 2
keywords: MSK; biomarker; laminin subunit alpha 2; proteomic