Purpose
The urothelium of cats diagnosed with feline interstitial cystitis (FIC) was analyzed to determine if abnormalities in protein expression patterns could be detected, and whether the pattern of expression was similar to that observed in human Interstitial Cystitis/Bladder Pain Syndrome (IC) patients. The proteins that were analyzed are involved in cell adhesion, barrier function, comprise the glycosaminoglycan (GAG) layer, or are markers of differentiation.
Methods
Formalin-fixed biopsies from 8 cats with FIC and 7 healthy controls were labeled using immunohistochemistry and scored using a modified version of a system previously used for human samples. Cluster analysis was performed to investigate relationships between the markers and samples.
Results
The results showed that 89% of the FIC bladders displayed abnormal protein expression and chondroitin sulfate (CS) patterns, whereas only 27% of the normal tissues exhibited slight abnormalities. Abnormalities were found in most of the FIC samples, biglycan (87.5%), CS (100%), decorin (100%), E-cadherin (100%), keratin-20 (K20, 100%), uroplakin (50%), ZO-1 (87.5%). In the FIC bladders, about 75% of the CS, biglycan, and decorin samples displayed absence of luminal staining or no staining. Results from the cluster analysis revealed that the FIC and normal samples fell into two clearly separate groups, demonstrating that the urothelium of cats with FIC is altered from normal.
Conclusions
FIC produces similar changes in luminal GAG and several proteins as is seen in human patients, suggesting some commonality in mechanism and supporting the use of FIC as a model for human IC.