Fosaprepitant improves cyclophosphamide-induced bladder damage by alleviating inflammatory response in mice

Inhibition of inflammatory process is a key therapeutic target for the treatment of interstitial cystitis (IC). Recent reports indicate that neurokinin 1 receptor (NK1R) antagonists have beneficial roles in inflammatory-based diseases. Herein, we investigate the protective effects of fosaprepitant (FOS), a NK1R antagonist, in cyclophosphamide (CP)-induced cystitis. The cystitis model was established multiple CP (80 mg/kg; i.p.) injection one day apart, and mice were treated with FOS (20 and 60 mg/kg/day; i.p.) for seven consecutive days. Detrusor contractility, vesical vascular permeability, myeloperoxidase (MPO) activity and protein expression levels of the TLR4 pathway were evaluated in mice bladder. Carbachol and electric field stimulation-evoked contractions of detrusor strips were significantly increased in CP-treated mice, which was significantly attenuated by FOS (60 mg/kg/day) treatment (p<0.001, p<0.05). Notably, vesical vascular permeability was markedly impaired in CP-induced cystitis, that was restored by FOS (60 mg/kg/day) treatment (p<0.01). MPO activity was significantly increased in cystitis group whereas FOS (20 and 60 mg/kg/day) treatment remarkably suppressed MPO activity in bladder tissue (p<0.001). Although TLR4 expression increased with cystitis, MyD88 and p-NFκB^Ser536/total NFκB did not change, FOS (20 and 60 mg/kg/day) treatment caused a dramatic decrease in TLR4 expression (p<0.001), indicating the anti-inflammatory effect of FOS. In conclusion, FOS improved detrusor overactivity and inflammatory response by inhibiting MPO activity and TLR4 expression, resulting in functional and histological recovery in CP-induced cystitis.