Suppressive activity of macrolide antibiotics on nitric oxide production from nasal polyp fibroblasts in vitro.

The influence of macrolide antibiotics on nitric oxide (NO) generation was examined using human nasal polyp fibroblasts (NPFs) in vitro. Addition of roxithromycin (RXM) at a concentration of > 7.5 microg/ml to cell cultures was shown to suppress NO production in response to stimulation with 25.0 ng/ml tumor necrosis factor (TNF)-alpha. However, jyosamycin (JM) did not suppress NO production from NPFs induced by TNF-alpha stimulation in vitro, even when added to cell cultures at a concentration of 20.0 microg/ml. We then examined the influence of RXM on inducible nitric oxide synthase (iNOS) mRNA expression in NPFs. Addition of RXM at a dose of 7.5 microg/ml to cell cultures caused reduction of iNOS mRNA expression, which was enhanced by TNF-alpha stimulation in vitro.