Biphasic regulation of levofloxacin on lipopolysaccharide-induced IL-1β production

Fluoroquinolones have been known to exert modulatory activity on immune responses to microbial infection. However, the mechanism of this immunomodulation has not been well elucidated. In this study, we investigated the effect of levofloxacin on lipopolysaccharide (LPS)-induced production of interleukin-1beta (IL-1β) in RAW264.7 cells. We showed that LPS-stimulated release of pre-synthesized IL-1β was promoted by levofloxacin, in part via the p38 mitogen-activated protein kinase (MAPK) pathway. On the other hand, newly synthesized IL-1β production was inhibited by levofloxacin. This immunoregulatory function of levofloxacin in the later phase as well as promotion of pre-synthesized IL-1β release by levofloxacin in the early phase might be advantageous in the host defense to microbial pathogens.