Tumor necrosis factor-alpha and interleukin-1beta mediate the production of nitric oxide involved in the pathogenesis of ifosfamide induced hemorrhagic cystitis in mice.

ABSTRACT

PURPOSE: We investigated the participation of nitric oxide in ifosfamide induced hemorrhagic cystitis in mice, and the involvement of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta in the induction of nitric oxide production in this model. MATERIALS AND METHODS: Hemorrhagic cystitis was induced in mice by 100 to 400 mg./kg. ifosfamide and evaluated 6, 12, 24 or 48 hours thereafter by certain parameters, including vesical edema measurements, microscopic analysis and immunohistochemical testing for inducible nitric oxide synthase. Ifosfamide injected mice were pretreated with 10 to 40 mg./kg. of the nitric oxide synthesis inhibitor L-NG-nitroarginine methyl ester, 80 mg./kg. of mesna, a chemical antagonist of acrolein and the urotoxic metabolite of ifosfamide, 50 microl. antiserum against TNF-alpha and IL-1beta per mouse, 45 mg./kg. of the selective TNF-alpha synthesis inhibitor thalidomide or 200 mg./kg. of the TNF-alpha and IL-1beta synthesis inhibitor pentoxifylline. RESULTS: Ifosfamide induced vesical edema, which peaked 12 hours after ifosfamide injection. Microscopic analysis revealed vascular congestion, edema, hemorrhage, fibrin deposition, neutrophil infiltration and epithelial denudation. Inducible nitric oxide synthase immunolocalization demonstrated intense reactivity to inducible nitric oxide synthase in the cytoplasm of bladder epithelial cells, which showed diffuse necrosis. Pretreatment with mesna reduced the increases in vesical edema, while treatment with L-NG-nitroarginine methyl ester, antiserum to TNF-alpha or IL-1beta, thalidomide or pentoxifylline inhibited vesical edema and microscopic alterations. Antiserum treatments also inhibited the expression of inducible nitric oxide synthase in the urothelium. CONCLUSIONS: Nitric oxide produced by inducible nitric oxide synthase is involved in urothelial damage and in the inflammatory events leading to hemorrhagic cystitis after ifosfamide administration in mice. The induction of inducible nitric oxide synthase in the urothelium appears to depend on the synergistic effect of IL-1beta and TNF-alpha.