Metallothionein overexpression of bladder biopsies associated with tissue hypoxia in patients with interstitial cystitis/painful bladder syndrome

Abstract

To study the relationship between hypoxia and metallothionein expression in bladder biopsies of interstitial cystitis/painful bladder syndrome patients. The study group consisted of 41 patients with interstitial cystitis/painful bladder syndrome, and the control group consisted of 12 volunteers without any interstitial cystitis/painful bladder syndrome symptoms. All biopsy specimens were analyzed for both proteins of hypoxia-inducible factor-1α and metallothionein expression by immunoblotting, immunostaining and confocal laser scanning microscopy. Data were analyzed using the Mann-Whitney U-test. An increased expression of hypoxia-inducible factor-1α and metallothionein was noted in the study group compared with the control group (P < 0.05). Both proteins of hypoxia-inducible factor-1α and metallothionein mainly distributed over bladder urothelium by immunohistochemical staining, and showed co-localization under confocal microscopy. High expression and co-localization of metallothionein and hypoxia-inducible factor-1 alpha in the bladder mucosa of patients with interstitial cystitis suggest that overexpression of metallothionein is associated with the bladder hypoxia related to this disease.