Proteomic techniques identify urine proteins that differentiate patients with interstitial cystitis from asymptomatic control subjects

Objective The purpose of this study was to identify differences in urine proteins between patients with interstitial cystitis (IC) and asymptomatic control (AC) subjects with the use of proteomic techniques. Study Design Nine patients with IC and their age-, race-, and sex-matched AC subjects volunteered a urine specimen. Urine proteins were separated with the use of 2-dimensional polyacrylamide gels. Differing proteins underwent digestion and matrix-assisted laser desorption ionization-time of flight mass spectrometry. Computer-assisted data analysis was used to identify the corresponding protein. Differences in urine protein responses between patients with IC and AC subjects were evaluated by the Mann-Whitney U test to account for the nonnormal frequency distribution of the parameter estimate or chi-square when data were bimodal. Results Four proteins differed significantly between patients with IC and AC subjects. The AC subjects had a greater concentration of a uromodulin ( P = .019) and two kininogens ( P = .023, .046). The patients with IC had a greater concentration of inter-alpha-trypsin inhibitor heavy chain H4 ( P = .019). Conclusion These urine protein isoforms may be biomarkers for IC.