Proteomic Profiling Identifies Haptoglobin as a Potential Serum Biomarker for Steroid-Resistant Nephrotic Syndrome

Abstract

<b><i>Background:</i></b> Long-term outcomes for patients with adult idiopathic nephrotic syndrome correlate closely with steroid responsiveness. The aim of this prospective study was to evaluate the difference in serum proteomes between steroid-sensitive nephrotic syndrome (SSNS) and steroid-resistant nephrotic syndrome (SRNS) patients and identify potential biomarkers for the prediction of SRNS. <b><i>Methods:</i></b> We performed a gel-based proteomic study of serum obtained from SRNS and SSNS patients and healthy controls at the time of presentation (n = 6 for each group). Proteins from the serum samples were separated using 2-D electrophoresis, digested in-gel and subjected to MALDI-TOF-MS/MS analysis. Further validation was performed utilizing Western blot and ELISA. The sensitivities and specificities of the candidate proteins for predicting SRNS were determined using receiver operating characteristic curves. <b><i>Results:</i></b> Thirteen differentially expressed proteins were identified as haptoglobin (Hp) with different isoelectric points and molecular weights. Western blot and ELISA analysis of samples from 146 subjects (healthy controls = 52, SSNS = 54, SRNS = 40) showed a markedly increased level of Hp in the serum, but not urine, of SRNS compared to SSNS patients. The optimal serum cutoff level of Hp was set at ≥1,279 µg/ml using the receiver operating characteristic curve. The sensitivity and specificity for predicting SRNS were 85.0 and 96.3%, respectively. <b><i>Conclusions:</i></b> This study provides a novel overview of the difference in serum proteomes of SSNS and SRNS patients. Serum Hp may be a useful predictive biomarker for steroid therapy efficacy in the treatment of idiopathic nephrotic syndrome.

Identification of a protein associated with the activity of cytokine‑induced killer cells

“…This was similar to the findings that an unknown protein spot identified as haptoglobin in patient sera using the mass spectra strategy (26)(27)(28). For further verification of the mass spectra results, western blotting was used (29), and the results demonstrated that haptoglobin protein was specificity connected with rabbit anti-human-haptoglobin. Therefore, it was concluded that the P43 protein was haptoglobin.…”

Urine Neutrophil Gelatinase Associated Lipocalin to Creatinine Ratio: A Novel Index for Steroid Response in Idiopathic Nephrotic Syndrome

“…Wen et al reported markedly elevated levels of haptoglobin in the serum of patients with SRNS, compared to SSNS [15]. In a recent uncontrolled study on a 38 patients with FSGS, fractional excretion of IgG was an independent predictor of remission, and urinary alpha 2-macroglobulin/Cr was a strong predictor of end stage renal disease [16].…”

Biomarkers in Rare Genetic Diseases

“…For instance, a pharmacological predictive biomarker has been reported in idiopathic nephrotic syndrome, a RD affecting the kidneys. Specifically, Wen et al [47] found a significant difference in the serum proteome of steroid-sensitive nephrotic syndrome (SSNS) and steroid-resistant nephrotic syndrome (SRNS, OMIM 256370) patients, predictive of their respective responses to treatment.…”