The Immunomodulatory Effects of Garenoxacin on Interleukin-8 Produced by Human Tonsillar Lymphocytes with Lipopolysaccharide Stimulation

Abstract

It has been reported that macrolides and some quinolones have an immunomodulatory effect and show synergy in their antimicrobial activity. Garenoxacin (GRNX), a recently developed fluoroquinolone, has been reported to show strong antimicrobial activity against respiratory pathogens such as Streptococcus pneumoniae and Haemophilus influenzae and high treatment efficacy for acute infectious diseases of the upper and lower respiratory tracts. To study the immunomodulatory effects of GRNX, we investigated its influence on interleukin-8 (IL-8), one of the products of proinflammatory cytokines, in human tonsillar lymphocytes stimulated with lipopolysaccharides (LPS). Palatine tonsils were obtained from patients with recurrent tonsillitis (n=12) and with hypertrophic tonsils (n=8). The tonsillar lymphocytes were stimulated with LPS (25 μg/ml) and were incubated with GRNX (5, 10, 15, 30 μg/ml) for 48 hours. IL-8 production of the treated lymphocytes was then measured with an ELISA. The IL-8 production of tonsillar lymphocytes was significantly suppressed by GRNX in the recurrent tonsillitis group, but not in the hypertrophic tonsil group. In conclusion, it is strongly suggested that GRNX has immunomodulatory effects on tonsillar lymphocytes with repeated episodes of infection through the suppression of IL-8 production. Thus GRNX has synergistic anti-inflammatory effects with its anti-bacterial properties, which is a favorable characteristic in the treatment of upper respiratory tract infections.