P2X2 and P2X3 receptor expression in human bladder urothelium and changes in interstitial cystitis

OBJECTIVE To investigate whether the expression of P2X(3) receptors (implicated in the pathophysiology of pain) is altered in human bladder urothelium from patients with interstitial cystitis (IC, a major symptom of which is pain), and as P2X(2) receptors can be co-expressed with P2X(3) receptors, to assess their expression also. PATIENTS AND METHODS Bladder tissue samples were collected from patients undergoing cystectomy or radical prostatectomy. Patients with IC were diagnosed using the international criteria. RNA protein expression levels of both receptors were evaluated using reverse transcription-polymerase chain reaction (PCR), real-time quantitative PCR and Western blot analysis. RESULTS P2X(2) was expressed in the human urothelium, in a glycosylated form. There was less gene expression of P2X(3) in IC urothelium, whereas P2X(2) gene expression was unchanged. This contrasted with the protein expression, which was increased for both P2X(2) and P2X(3). CONCLUSION This is the first report of the expression of the P2X(2) receptor in human bladder urothelium. There was greater protein expression of both P2X(2) and P2X(3) in IC bladder urothelium which did not directly correlate with the gene expression. Changes in expression of P2X(2) and P2X(3) receptors may contribute to the pain that patients with IC have, and might provide novel drug targets.