Nemonoxacin Has Immunoprotective Effects on Reducing Mortality in Lipopolysaccharide-Induced Mouse Sepsis Model

Nemonoxacin is a novel non-fluorinated quinolone. The effect of nemonoxacin on modulation of host immune response is not known. We sought to determine whether nemonoxacin has immunoprotective effects on lipopolysaccharide (LPS)-induced mouse sepsis model. Therefore, mice were challenged with lethal dose LPS (12.5 mg/kg) only or LPS with multi-dose nemonoxacin (40 mg/kg q12h) by intraperitoneal injection, and the results showed nemonoxacin could significantly reduce mortality from 80 to 30% in this model. The effect of nemonoxacin on immune cells in vivo and in vitro was also investigated. Mice were treated with sublethal LPS (5 mg/kg) or LPS + nemonoxacin, the myeloid cell subsets in mouse spleen were analyzed by flow cytometry, and cytokines in mouse serum were measured by ELISA. Additionally, mouse macrophage RAW264.7 cells were treated with LPS or LPS + nemonoxacin to investigate the immune modulatory effect of nemonoxacin in vitro, and the level of cytokines in cell culture supernatant was determined by ELISA. Analysis of myeloid cell subsets in the spleen showed nemonoxacin pretreatment could significantly inhibit LPS-induced proliferation of macrophages and dendritic cells but have no effect on neutrophils. Nemonoxacin could significantly reduce the expression of pro-inflammatory cytokines IL-6 and TNF-α while increase anti-inflammatory cytokine IL-10 expression, which were induced by LPS in vivo and in vitro. Finally, the immunomodulation of nemonoxacin in macrophage phagocytosis was also examined. The results displayed nemonoxacin pretreatment could significantly enhance the phagocytic function of macrophage. In conclusion, nemonoxacin has immune modulatory and protective effect on LPS-induced inflammation in vivo and in vitro.