Study of the apoptotic effect of urine as a diagnostic biomarker in patients with interstitial cystitis

The main objective of the study was to assess the apoptotic effect of urine from patients with interstitial cystitis (IC) in cell cultures and to study its value as a diagnostic biomarker for IC. A prospective study was conducted between January 2010 and January 2015 and included 57 patients diagnosed with IC and 50 healthy patients from the Hospital Clinic of Barcelona and the La Paz University Hospital. The urine of these patients was exposed to cell cultures, and its ability to induce apoptosis in the cultures was analysed. Using flow cytometry, we then measured the degree of apoptosis, quantified by the percentage of cells of the cell cycle in phase sub G0. The cell cultures exposed to the urine of patients with IC had a sub G1 peak and a G2 phase, which was significantly greater than that of the control group, and a significantly lower percentage in the S phase than the control group. The mean apoptosis values in the urine cultures from patients with IC were significantly higher than those of the control group. Using a value >10% of the apoptosis test as a positive result, we observed a specificity of 96% and a positive predictive value of 92%. The urine of patients with IC exerts an apoptotic effect on tumour cell cultures that is significantly greater than that exerted by the urine of healthy control patients. A≥10% cutoff for the apoptosis test presented very low sensitivity (40%) but had a very high specificity (96%), thereby able to confirm the diagnosis of IC when positive.