Azithromycin Polarizes Macrophages to an M2 Phenotype via Inhibition of the STAT1 and NF-κB Signaling Pathways

Content Provider	Scilit
Author	Haydar, Dalia Cory, Theodore J. Birket, Susan E. Murphy, Brian S. Pennypacker, Keith R. Sinai, Anthony P. Feola, David J.
Copyright Year	2019
Description	Azithromycin is effective at controlling exaggerated inflammation and slowing the long-term decline of lung function in patients with cystic fibrosis. We previously demonstrated that the drug shifts macrophage polarization toward an alternative, anti-inflammatory phenotype. In this study we investigated the immunomodulatory mechanism of azithromycin through its alteration of signaling via the NF-κB and STAT1 pathways. J774 murine macrophages were plated, polarized (with IFN-γ, IL-4/-13, or with azithromycin plus IFN-γ) and stimulated with LPS. The effect of azithromycin on NF-κB and STAT1 signaling mediators was assessed by Western blot, homogeneous time-resolved fluorescence assay, nuclear translocation assay, and immunofluorescence. The drug's effect on gene and protein expression of arginase was evaluated as a marker of alternative macrophage activation. Azithromycin blocked NF-κB activation by decreasing p65 nuclear translocation, although blunting the degradation of IκBα was due, at least in part, to a decrease in IKKβ kinase activity. A direct correlation was observed between increasing azithromycin concentrations and increased IKKβ protein expression. Moreover, incubation with the IKKβ inhibitor IKK16 decreased arginase expression and activity in azithromycin-treated cells but not in cells treated with IL-4 and IL-13. Importantly, azithromycin treatment also decreased STAT1 phosphorylation in a concentration-dependent manner, an effect that was reversed with IKK16 treatment. We conclude that azithromycin anti-inflammatory mechanisms involve inhibition of the STAT1 and NF-κB signaling pathways through the drug's effect on p65 nuclear translocation and IKKβ.
Ending Page	1030
Page Count	10
Starting Page	1021
ISSN	00221767
e-ISSN	15506606
DOI	10.4049/jimmunol.1801228
Journal	The Journal of Immunology
Issue Number	4
Volume Number	203
Language	English
Publisher	The American Association of Immunologists
Publisher Date	2019-08-15
Access Restriction	Open
Subject Keyword	Nf Κb Anti Inflammatory P65 Nuclear Translocation Κb Signaling Pathways Stat1 and Nf Azithromycin Is Effective
Content Type	Text
Resource Type	Article
Subject	Immunology and Allergy Immunology