Ayako Furuya

Suppression of nitric oxide production from nasal fibroblasts by metabolized clarithromycin in vitro

BackgroundLow-dose and long-term administration of 14-membered macrolide antibiotics, so called macrolide therapy, has been reported to favorably modify the clinical conditions of chronic airway diseases. Since there is growing evidence that macrolide antibiotic-resistant bacterias spreaders in the populations received macrolide therapy, it is strongly desired to develop macrolide antibiotics, which showed only anti-inflammatory action. The present study was designed to examine the influence of clarithromycin (CAM) and its metabolized materials, M-1, M-4 and M-5, on free radical generation from nasal polyp fibroblasts (NPFs) through the choice of nitric oxide (NO), which is one of important effector molecule in the development of airway inflammatory disease in vitro.MethodsNPFs (5 × 105 cells/ml) were stimulated with 1.0 μg/ml lipopolysaccharide (LPS) in the presence of agents for 24 hours. NO levels in culture supernatants were examined by the Griess method. We also examined the influence of agents on the phosphorylation of MAPKs, NF-κB activation, iNOS mRNA expression and iNOS production in NPFs cultured for 2, 4, 8, and 12 hours, respectively.ResultsThe addition of CAM (> 0.4 μg/ml) and M-4 (> 0.04 μg/ml) could suppress NO production from NPFs after LPS stimulation through the suppression of iNOS mRNA expression and NF-κB activation. CAM and M-4 also suppressed phosphorylation of MAPKs, ERK and p38 MAPK, but not JNK, which are increased LPS stimulation. On the other hand, M-1 and M-5 could not inhibit the NO generation, even when 0.1 μg/ml of the agent was added to cell cultures.ConclusionThe present results may suggest that M-4 will be a good candidate for the agent in the treatment of chronic airway inflammatory diseases, since M-4 did not have antimicribiological effects on gram positive and negative bacteria.

Suppressive activity of fexofenadine hydrochloride on nitric oxide production in-vitro and in-vivo.

The aim of this study was to examine the effect of fexofenadine hydrochloride (FEX), a histamine H1‐ receptor antagonist, on nitric oxide (NO) production in‐vitro and in‐vivo. Nasal fibroblasts (5 × 105 cells per mL) were stimulated with 25 ng mL−1 tumour necrosis factor‐α in the presence of various concentrations of FEX. NO levels in 24‐h‐culture supernatants were measured by the Griess method and levels of inducible nitric oxide synthase (iNOS) mRNA levels in 12‐h‐cultured cells were measured by ELISA. FEX at more than 0.5 μg mL−1 suppressed NO production from fibroblasts by inhibiting expression of iNOS mRNA. We also examined whether FEX could suppress NO production induced by lipopolysaccharide (LPS) stimulation in‐vivo. BALB/c mice were treated with 5.0 mg kg−1 LPS i.p. after daily oral doses of FEX, 1.0 mg kg−1, for 1–3 weeks. Plasma was obtained 6 h later and NO levels measured by the Griess method. Expression of iNOS mRNA in lung tissues was measured by ELISA 6h after LPS injection. Oral administration of FEX for 2 and 3 weeks, but not 1 week, significantly suppressed NO levels in plasma through the inhibition of iNOS mRNA expression, which were enhanced by LPS stimulation. These results suggest that the attenuating effect of FEX on NO production may be of therapeutic benefit in allergic diseases.