Effect of pro-inflammatory cytokines on urothelial cell adenosine triphosphate release and breakdown

Objectives: Urinary symptoms of urgency, frequency, and pain are thought to be the result of inflammation in several bladder pathologies although the cause of these symptoms remains uncertain. Extracellular adenosine triphosphate (ATP) released from the bladder urothelium during normal bladder stretch is believed to bind to purinergic receptors on afferent nerves to signal bladder sensation. This study examined pro-inflammatory cytokines in the urine of women with detrusor overactivity (DO) with or without urinary tract infection (UTI) compared to controls and then determined the effect of pro-inflammatory cytokines on ATP signaling (release and breakdown) from the urothelium. Methods: The urinary concentrations of interferon-gamma (IFN-), tumor necrosis factor-alpha (TNF-), and interleukin-1 beta (IL-1) were determined in women with DO with or without UTI compared to female controls. The effect of pro-inflammatory cytokines (IFN-, TNF-, and IL-1) on control and hypotonic-induced ATP release using human UROtsa urothelial cells was examined, as was the effect of these cytokines on nucleotide (ATP, adenosine diphosphate and adenosine monophosphate) breakdown. Results: Urinary concentrations of IFN-, TNF-, and IL-1 were increased in women with DO and UTI. Pre-treatment of urothelial cells with individual cytokines stimulated a decrease rather than an increase in ATP release whereas pre-treatment with a cocktail of all three cytokines stimulated a small but significant increase in hypotonic-induced ATP release. Pre-treatment of urothelial cells with cytokines significantly enhanced nucleotide breakdown. Conclusion: Using a simple cell culture model we have demonstrated that the response of the urothelium to pro-inflammatory cytokines is complex, affecting both release and breakdown of ATP.