Modulation of nitric oxide response by fluoroquinolones

In this study, we examined the effects of fluoroqinolones, namely ciprofloxacin (CIP) and ofloxacin (OFX) on nitric oxide (NO) production in an in vitro lipopolysaccharide(LPS)-activated macrophage model. Thioglycollate-elicited;ed peritoneal cells from BALB/c mice were exposed to varying concentrations of CIP and OFX for 1 or 4 days before LPS stimulation. NO response was measured by nitrite accumulation. On the first day of antibiotic exposure, nitrite production after LPS stimulation (1 mu g/ml) decreased by 49.3% (p<0.05), 77.9% (p<0.05), 3.8% (p>0.05) and by 29.7% (p<0.05), 20.5% (p<0.O5), 0.0% (p>0.05) in the presence of 1 mM, 100 mu M and 10 mu M CIP and OFX, respectively. The inhibitory effects did not change significantly after 4 days' of exposure. The results indicate that, in this in vitro murine macrophage model, fluoroquinolones inhibit nitrite production in a dose-dependent manner and may have similar immunomodulatory effects in vivo.