Increased concentration of neutrophil elastase in urine from patients with interstitial cystitis

Objective. To identify proteins associated with interstitial cystitis (IC), protein profiles were analyzed using a proteomics-based approach. The study tested whether neutrophil elastase in urine correlates with the symptomatic condition of IC. Material and methods. Proteins in urine from IC patients and healthy subjects were analyzed through a comparative proteomics approach using two-dimensional difference in-gel electrophoresis and nano-liquid chromatography-tandem mass spectrometry. Neutrophil elastase activity was measured by the digestion of peptide substrate. Results. The urinary neutrophil elastase concentration was significantly higher in IC patients with pain than in healthy subjects. It was significantly increased in patients with small bladder capacity (median 6.31 ng/ml in IC with a bladder capacity 200 ml vs 1.15 ng/ml in IC with a bladder capacity 200 ml and 0.18 ng/ml in healthy bladders, p0.01). The concentration of neutrophil elastase did not correlate with the neutrophil count in the urine of IC patients. Conclusion. The concentration of neutrophil elastase increased in the urine of the IC patient subset with bladder pain and small bladder capacity.