Pirfenidone induces intercellular adhesion molecule-1 (ICAM-1) down-regulation on cultured human synovial fibroblasts

Pirfenidone inhibits NADPH-dependent microsomal lipid peroxidation and scavenges hydroxyl radicals

Pirfenidone (Pf), a new broad-spectrum anti-fibrotic agent, is known to offer protection against lung fibrosis in vivo in laboratory animals, and against mitogenesis and collagen formation by human lung fibroblasts in vitro. Because reactive oxygen species are thought to be involved in these events, we investigated the mechanism(s) by which Pf ameliorates oxidative stress and its effects on NADPH-dependent lipid peroxidation. Pf has been shown to cause inhibit NADPH-dependent lipid peroxidation in sheep liver microsomes in a dose-dependent manner. The concentration of Pf required to cause 50% inhibition of lipid peroxidation was approximately 6 mM. Pf was found to be ineffective as a superoxide radical scavenger. Pf was also ineffective in decomposing H2O2 and chelating iron. In deoxyribose degradation assays, Pf was a potent scavenger of hydroxyl radicals with a rate constant of 5.4 x 10(9) M(-1) sec(-1). EPR spectroscopy in combination with spin trapping techniques, using a Fenton type reaction and DMPO as a spin-trapping agent, Pf scavenged hydroxyl radicals in a dose-dependent manner. The concentration of Pf required to inhibit 50% signal height was approximately 2.5 mM. Because iron was used in the Fenton reaction, the ability of Pf in chelating iron was verified in a fluorescent competitive assay using calcein as the fluorescent probe. Pf up to 10 mM concentration was ineffective in chelating either Fe2+ or Fe3+ in this system. We propose that Pf exerts its beneficial effects, at least in part, through its ability to scavenge toxic hydroxyl radicals.

Effects of clarithromycin on cultured human nasal epithelial cells and fibroblasts

OBJECTIVE/METHODS

Long-term administration of clarithromycin has been reported to be effective in the treatment of chronic sinusitis. To investigate the mechanism underlying the anti-inflammatory activity of clarithromycin, the authors evaluated the effect of clarithromycin on the gene expression of proinflammatory cytokine and the DNA-binding activity of nuclear factor (NF)-kappa B in cultured human nasal epithelial cells and fibroblasts. Cells were incubated with endotoxin purified from nontypable Haemophilus influenzae or interleukin (IL)-1 beta in the presence of clarithromycin.

RESULTS

Northern blot analysis revealed that clarithromycin suppressed IL-1 beta gene expression in human nasal epithelial cells stimulated by H. influenzae endotoxin (HIE). Intercellular adhesion molecule-1 gene expression in nasal fibroblasts stimulated by IL-1 beta was also suppressed by clarithromycin. Furthermore, electrophoretic mobility shift assay demonstrated that clarithromycin reduced DNA-binding activity of NF-kappa B in both human nasal epithelial cells and fibroblasts stimulated by HIE or IL-1 beta, respectively.

CONCLUSION

The present results suggest that clarithromycin may reduce gene expression of proinflammatory cytokines and adhesion molecules from nasal mucosa at the transcriptional factor level and exert an anti-inflammatory effect on nasal mucosa in chronic sinusitis.