Increased urinary leukotriene E4 and eosinophil protein X excretion in patients with interstitial cystitis

The role of cysteinyl containing leukotriene C4, D4 and E4, and eosinophil protein X in interstitial cystitis is unknown. Leukotriene E4, the end product of cysteinyl containing leukotrienes, and eosinophil protein X are markers of the activation of mast cells and eosinophils, respectively. Cysteinyl containing leukotrienes are potent and specific chemoattractants for eosinophils. We compared the urinary excretion of leukotriene E4 and eosinophil protein X in patients with interstitial cystitis and in healthy controls.

Morning spot urine samples from nine patients with interstitial cystitis who fulfilled National Institute of Diabetes and Digestive and Kidney Diseases criteria were collected on the day of cystoscopy with biopsies. Aliquots of urine specimens were immediately centrifuged and the supernatants were stored at -80C until use. Urine samples from 9 healthy women served as controls. Urinary leukotriene E4 and eosinophil protein X were measured by enzyme immunoassay and radioimmunoassay, respectively. All determinations were performed in duplicate and normalized to urine creatinine.

Leukotriene E4 and eosinophil protein X were significantly increased in the morning urine of patients with interstitial cystitis compared with controls. The mean urinary excretion of leukotriene E4 plus or minus standard deviation was 148.8 +/- 62.5 and 62.2 +/- 17.5 ng./mmol. creatinine in patients and controls (p = 0.003), while the mean urinary excretion of eosinophil protein X was 109.7 +/- 70.4 and 43.7 +/- 22.0 microg./mmol. creatinine, respectively (p = 0.01). All urine cultures were negative. The mean mast cell count in detrusor biopsies in the interstitial cystitis group was 41 cells per mm.2 (range 5 to 84). Eosinophilic granulocytes were occasionally observed in the submucosa but not in the detrusor.

Our study shows that patients with interstitial cystitis and detrusor mastocytosis have increased urinary leukotriene E4 and eosinophil protein X. It is possible that cysteinyl containing leukotrienes and eosinophil protein X are involved in the pathogenesis of interstitial cystitis. Urinary leukotriene E4 and eosinophil protein X may be useful markers for assessing the grade of activation of mast cells and eosinophils in patients with interstitial cystitis and/or for confirming the diagnosis. However, it remains to be investigated whether the increase in urinary leukotriene E4 and eosinophil protein X correlates with interstitial cystitis symptoms.