Role of mast cells and protease-activated receptor-2 in cyclooxygenase-2 expression in urothelial cells

Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin Submitted June 3, 2009 ; accepted in final form August 9, 2009 Mast cells have been shown to play a role in development and persistence of various inflammatory bladder disorders. Mast cell-derived tryptase specifically activates protease-activated receptor-2 (PAR-2), and PAR-2 is known to be involved in inflammation. We investigated whether mast cells participate in increase of cyclooxygenase-2 (COX-2) protein abundance in urothelium/suburothelium of bladders of mice subsequent to cyclophosphamide (CYP)-induced bladder inflammation. We also used primary cultures of human urothelial cells to investigate cellular mechanisms underlying activation of PAR-2 resulting in increased COX-2 expression. We found that treatment of mice with CYP (150 mg/kg ip) increased COX-2 protein abundance in bladder urothelium/suburothelium 3, 6, and 24 h after CYP ( P < 0.01), and increased COX-2 protein abundance was prevented by treatment of mice with the mast cell stabilizer sodium cromolyn (10 mg/kg ip) for 4 consecutive days before CYP treatment. Incubation of freshly isolated mouse urothelium/suburothelium with a selective PAR-2 agonist, 2-furoyl-LIGRLO-amide (3 µM), also increased COX-2 protein abundance ( P < 0.05). We further demonstrated that 2-furoyl-LIGRLO-amide (3 µM) increased COX-2 mRNA expression and protein abundance in primary cultures of human urothelial cells ( P < 0.01), and the effects of PAR-2 activation were mediated primarily by the ERK1/2 MAP kinase pathway. These data indicate that there are functional interactions among mast cells, PAR-2 activation, and increased expression of COX-2 in bladder inflammation. urothelium; cyclophosphamide; mouse; inflammation; bladder Address for reprint requests and other correspondence: Z.-Y. Wang, Dept. of Surgical Sciences, School of Veterinary Medicine, Univ. of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53719 (e-mail: wangz{at}svm.vetmed.wisc.edu ).