Sensory Receptor, Inflammatory, and Apoptotic Protein Expression in the Bladder Urothelium of Patients with Different Subtypes of Interstitial Cystitis/Bladder Pain Syndrome

Abstract

The aim of this study was to investigate the expression levels of sensory receptors, inflammatory proteins, and pro-apoptotic proteins in the urothelium of non-Hunner’s interstitial cystitis (NHIC) bladders of patients with different clinical and cystoscopic phenotypes. The urothelia from the bladders of 52 NHIC patients were harvested. The expression of sensory receptors, including TRPV1, TRPV4, TRPA1, H1-receptors, and sigma-1 receptors; the inflammatory proteins p38 and tryptase; and the pro-apoptotic proteins, such as caspase-3, BAD, and BAX in the urothelium, were investigated using immunohistochemistry and Western blotting. We compared the expression levels of these proteins in NHIC subtypes according to IC symptom scores, visual analog scores of bladder pain, maximal bladder capacity, glomerulation grades, and combined maximal bladder capacity and glomerulations after cystoscopic hydrodistention. The expression levels of TRPV1, TRPV4, sigma-1, P38, tryptase, caspase-3, and BAD were significantly increased in the urothelium of IC/BPS patients compared with the expression levels in the controls. TRPV1 was significantly associated with IC symptom severity. However, no significant differences in sensory receptor expression in the IC/BPS bladders with different bladder conditions were detected. Inflammatory and pro-apoptotic protein expression levels in the urothelium were similar among the IC/BPS subgroups. This study concluded that IC/BPS patients with frequency and bladder pain complaints have higher levels of urothelial sensory receptors, and inflammatory and pro-apoptotic proteins. The expression levels of these sensory receptors, inflammatory proteins, and pro-apoptotic proteins are not significantly different among IC/BPS bladders with different conditions.