Deletion or pharmacological blockade of toll-like receptor 4 (TLR4) confers protection against cyclophosphamide-induced mouse cystitis

Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is a chronic inflammatory disease without consistently effective treatment. We investigate the role of toll-like receptor (TLR4) on voiding dysfunction and inflammation in the cyclophosphamide (CYP)-induced mouse cystitis. Males C57BL/6 (wild-type, WT) and/or TLR4 knockout (TLR4-/-) were treated with an injection of CYP (300 mg/kg, 24 h) or saline (10 ml/kg). The pharmacological blockade of the TLR4 by resatorvid (10 mg/kg) was also performed 1 h prior CYP-injection in WT mice. Urodynamic profiles were assessed by voiding stain on filter paper and filling cystometry. Contractile responses to carbachol were measured in isolated bladders. In CYP-exposed WT mice, mRNA for TLR4, MyD88 and TRIF increased by 45%, 72% and 38%, respectively (P < 0.05). In free-moving mice, CYP-exposed mice exhibited higher number of urinary spots and smaller urinary volumes. Increases of micturition frequency and non-voiding contractions, concomitant with decreases of intercontraction intervals and capacity were observed in the filling cystometry of WT mice (P < 0.05). Carbachol-induced bladder contractions were significantly reduced in the CYP group, which was paralleled by reduced mRNA for M2 and M3 muscarinic receptors. These functional and molecular alterations induced by CYP were prevented in TLR4-/- and resatorvid-treated mice. Additionally, the increased levels of inflammatory markers induced by CYP exposure (MPO activity, IL-6 and TNF-α) were significantly reduced by resatorvid treatment. Our findings reveal a central role for TLR4 signaling pathway in initiating CYP-induced bladder dysfunction and inflammation, and thus emphasize that TLR4 receptor blockade may have clinical value for IC/BPS treatment.

American journal of physiology. Renal physiology. 2018 May 02 [Epub ahead of print]

Mariana G de Oliveira, Fabiola Zakia Mónica, Fabiano B Calmasini, Eduardo C Alexandre, Edith B G Tavares, Antonio G Soares, Soraia K P Costa, Edson Antunes

Pharmacology, UNICAMP, Brazil., UNICAMP, Brazil., Pharmacology, State University of Campinas., Department of Pharmacology, University of Campinas (UNICAMP), Brazil., Faculty of Medical Sciences, Department of Pharmacology, University of Campinas., Institute of Biomedical Sciences, Department of Pharmacology, University of São Paulo., Pharmacology, State University of Campinas (UNICAMP), Brazil.

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