Purine nucleoside phosphorylase inhibition is an effective approach for the treatment of chemical hemorrhagic cystitis
Amanda Wolf-Johnston, Youko Ikeda, Irina Zabbarova, Anthony J. Kanai, Sheldon Bastacky, Robert Moldwin, Joel N.H. Stern, Edwin K. Jackson, Lori A. Birder
Amanda Wolf-Johnston, Youko Ikeda, Irina Zabbarova, Anthony J. Kanai, Sheldon Bastacky, Robert Moldwin, Joel N.H. Stern, Edwin K. Jackson, Lori A. Birder
View: Text | PDF
Research Article Inflammation

Purine nucleoside phosphorylase inhibition is an effective approach for the treatment of chemical hemorrhagic cystitis

Abstract

Hemorrhagic cystitis may be induced by infection, radiation therapy, or medications or may be idiopathic. Along with hemorrhagic features, symptoms include urinary urgency and frequency, dysuria (painful urination), and visceral pain. Cystitis-induced visceral pain is one of the most challenging types of pain to treat, and an effective treatment would address a major unmet medical need. We assessed the efficacy of a purine nucleoside phosphorylase inhibitor, 8-aminoguanine (8-AG), for the treatment of hemorrhagic/ulcerative cystitis. Lower urinary tract (LUT) function and structure were assessed in adult Sprague-Dawley rats, treated chronically with cyclophosphamide (CYP; sacrificed day 8) and randomized to daily oral treatment with 8-AG (begun 14 days prior to CYP induction) or its vehicle. CYP-treated rats exhibited multiple abnormalities, including increased urinary frequency and neural mechanosensitivity, reduced bladder levels of inosine, urothelial inflammation/damage, and activation of spinal cord microglia, which is associated with pain hypersensitivity. 8-AG treatment of CYP-treated rats normalized all observed histological, structural, biochemical, and physiological abnormalities. In cystitis 8-AG improved function and reduced both pain and inflammation likely by increasing inosine, a tissue-protective purine metabolite. These findings demonstrate that 8-AG has translational potential for reducing pain and preventing bladder damage in cystitis-associated LUT dysfunctions.

Authors

Amanda Wolf-Johnston, Youko Ikeda, Irina Zabbarova, Anthony J. Kanai, Sheldon Bastacky, Robert Moldwin, Joel N.H. Stern, Edwin K. Jackson, Lori A. Birder

×

Figure 3

8-AG restores CYP-associated changes in bladder blood flow and proteins linked with oxidative stress and visceral nociception in the rat bladder.

Options: View larger image (or click on image) Download as PowerPoint
8-AG restores CYP-associated changes in bladder blood flow and proteins ...
(A) Western immunoblotting shows significant alterations by CYP in the expression of nitrotyrosine (n = 12–15 per group), a biomarker for peroxynitrite action in conditions of cell damage and oxidative stress; (B) NLRP3 (n = 8 per group), an intracellular sensor that detects danger signals and results in activation of the NLRP3 inflammasome; (C) TLR4 (n = 12–16 per group), a protein belonging to the pattern recognition receptor family with a key role in amplifying the inflammatory response; (D) HIF-1alpha (n = 7–8 per group), which plays an important role in inflammatory processes; and (E) PECAM-1 (n = 11–13 per group), a cellular adhesion and signaling receptor protein expressed at junctions between endothelial cells. (F) Doppler flow meter measurements revealing a significant increase in bladder blood flow in CYP-rats compared with control untreated rat bladders (n = 12–15 per group). In all cases, treatment with 8-AG blocked CYP-induced changes such that CYP + 8-AG bladders were similar to control, healthy bladders. Upper insets (A–E) show representative bands from Western immunoblotting. Densitometry was normalized to total protein staining (loading control [LC]; representative bands shown in lower inset). Representative bands were run on the same blot but were noncontiguous. Data are presented as means ± SD. Ordinary 1-way ANOVA followed by either Tukey’s post hoc or Newman-Keuls multiple-comparison test was used to evaluate significance; *P < 0.05, **P < 0.01; ***P < 0.0001.