| Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS), a chronic inflammatory bladder disease of unknown etiology, has been associated with several modifiable risk factors including diet, weight and smoking. In these studies, the impact of cigarette smoking on bladder platelet activating factor (PAF) production and its involvement in promoting inflammation and urothelial damage was determined. Cigarette smoke extract (CSE) exposure significantly increased endothelial cell PAF production resulting in inflammatory cell adherence which can be inhibited by use of the PAF receptor antagonists, ginkgolide B and WEB 2086. PAF-acetylhydrolase (PAF-AH), which normally maintains PAF at low levels, was significantly inhibited following CSE incubation at times corresponding to the increased PAF production. Using pharmacological inhibitors of calcium-independent phospholipase A2 (iPLA2), the enzyme necessary for PAF synthesis, we observed that iPLA2beta is the predominant iPLA2 involved in endothelial and urothelial cell PAF production. In wild-type C57Bl/6 mice exposed to mainstream cigarette smoke for 48 minutes/day, 5 days/week for 1 month we detected increased inflammatory cell infiltration in the bladder wall compared to their iPLA2betaKO counterparts. When the smoking period was extended to 6 months, we observed nuclear localization of the PAF receptor and urothelial damage in wild-type animals which was not seen in the iPLA2betaKO animals. CSE incubation of urothelial cells derived from healthy patients displayed increased PAF production with a more substantial increase in PAF production in urothelial cells derived from IC/BPS patient. CSE exposure to urothelial cells delayed their development of electrical resistance and slowed their rate of wound healing. Finally, we measured the urinary PAF concentration in normal, IC/BPS non-smokers and IC/BPS smokers. The urinary PAF concentration in IC/BPS non-smokers was significantly increased compared to healthy individuals. In IC/BPS patients that smoke, the urinary PAF concentration was substantially increased compared to non-smokers. The data presented in this thesis provide evidence that cigarette smoking promotes bladder inflammation and urothelial cell damage. This data suggests that smoking could be a precipitating factor for inflammatory bladder diseases such as IC/BPS. Additionally we show that therapeutic targeting of iPLA2beta or the PAF receptor could be beneficial in managing inflammatory bladder diseases. |
