Urinary Sphingosine-1-Phosphate as a Biomarker for Bladder Pain Syndrome

IMPORTANCE: Sphingosine-1-phosphate (S1P) is a signaling molecule involved in inflammation and bladder contraction. OBJECTIVES: The aims of this case-control pilot study were to compare urinary S1P concentrations in bladder pain syndrome (BPS) participants to controls and determine whether these concentrations correlate with disease severity and duration. STUDY DESIGN: Adult females with BPS and controls were enrolled. Bladder pain syndrome participants completed an O'Leary-Sant questionnaire. Information on duration of symptoms and treatment history was obtained. Urinary S1P and creatinine concentrations were determined. Mann-Whitney U tests were used to compare groups, and Spearman correlation was used to test for associations between concentrations and duration and severity of symptoms. RESULTS: Twenty-five participants were in each group. Median S1P concentration was 1,225 ng/dL in the BPS group and 2,183 ng/dL in the control group, which was significantly different (P < 0.0001). This difference did not persist when normalized to urinary creatinine (P = 0.58). No differences were noted in urinary S1P concentrations between treated and untreated participants (P = 0.53) or with symptom scores of 13 or greater and less than 13 (P = 0.69). Sphingosine-1-phosphate levels did not correlate with O'Leary-Sant scores (P = 0.08) or duration of symptoms (P = 0.67). Results did not change when using S1P concentrations normalized to creatinine. CONCLUSIONS: This study demonstrated successful quantification of human urinary S1P concentrations. A difference in urinary S1P was found between BPS participants and controls but not when normalized to creatinine. While this is the first study to investigate urinary S1P as a biomarker for BPS, results suggest that it may have a potential role as a biomarker requiring further research.