Anti-inflammatory effects of azithromycin in cystic fibrosis airway epithelial cells.

We aimed at identifying molecular mechanisms for anti-inflammatory effects of azithromycin (AZM) suggested by clinical evidences. IL-8 expression and DNA binding activity of two key pro-inflammatory transcription factors (TF), NF-kappaB and AP-1, were investigated in cystic fibrosis (CF) and isogenic non-CF airway epithelial cell lines. AZM reduced about 40% of IL-8 mRNA and protein expression (n=9, p=0.02, and n=4, p=0.00011) in CF cells reaching the levels of non-CF cells. In the presence of AZM we found about 50% and 70% reduction of NF-kappaB and AP-1 DNA binding, respectively (n=3, p=0.01, and n=3, p=0.0017), leading to levels of non-CF cells. The relevance of NF-kappaB and AP-1 in regulating IL-8 promoter transcriptional activity was demonstrated by gene reporter assays (n=4, p=8.54x10(-7), and n=4, p=6.45x10(-6)). Our data support the anti-inflammatory effects of AZM in CF cells, indicating inhibition of transcription of pro-inflammatory genes as possible mechanism, thus providing a rationale for the possible use of specific TF inhibitors for therapy.