Investigating the effect of pretreatment with azithromycin on inflammatory mediators in bronchial epithelial cells exposed to cigarette smoke

Abstract

Purpose of the study: Macrolide therapy is effective in reducing chronic obstructive pulmonary disease (COPD) exacerbations. Our recent study has shown the effectiveness of taking azithromycin in COPD patients, not only ex-smokers but also current smokers. Beyond their anti-microbial effects, macrolides have anti-inflammatory and immunomodulatory properties. The aim of this study was to determine if pretreatment with azithromycin modulates cigarette smoke-induced inflammation in airway epithelial cells. We hypothesized that pretreatment with azithromycin decreases exacerbation frequency by modulating inflammation in human airway epithelial cells exposed to cigarette smoke.

Materials and methods: BEAS-2B bronchial epithelial cells were incubated with 5% cigarette smoke extract (CSE) for 3 h, 6 h, and 24 h. Then, airway epithelial cells were pretreated with azithromycin and exposed to 5% CSE. In each stage, the expression and release of IL-6 and IL-8 mRNA were analyzed by quantitative real-time PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively.

Results: There was a significant increase of IL-6 and IL-8 mRNA, as well as an increase in extracellular IL-8 protein following exposure to 5% CSE. When cells were pretreated with azithromycin and exposed to 5% CSE for 3 h, there was a significant dose-dependent decrease in the expression of IL-6 mRNA. A final concentration of 9 µg/mL of azithromycin was sufficient to decrease IL-6, IL-8 mRNA, and extracellular IL-8 levels.

Conclusion: Pretreatment with azithromycin decreased the expression of IL-6 and IL-8 mRNA and the release of IL-8 in bronchial epithelial cells exposed to cigarette smoke. These results demonstrate the direct effect of azithromycin on inflammatory mediators in bronchial epithelial cells exposed to cigarette smoke.

Keywords:

• Azithromycin
• BEAS-2B cells
• COPD exacerbations

Disclosure statement

Nafiseh Naderi reports an award from Meakins-Christie Laboratories, Research Institute of McGill University Health Center, and a grant from Réseau en Santé Respiratoire du FRQS, during the conduct of the study. Raquel Farias reports grants from Research Institute of McGill University Health Center, from Réseau en Santé Respiratoire du FRQS, during the conduct of the study. Mira Abou Rjeili, SMY Mostafavi-Pour-Manshadi, Suurya Krishnan, and Pei Zhi Li have no conflict of interest. Caroline J. Baglole reports grants from CIHR outside the submitted work. Jean Bourbeau reports grants from CIHR, grants from Canadian Respiratory Research Network (CRRN), personal fees from Canadian Thoracic Society, personal fees from CHEST, grants from Foundation of the MUHC, grants from Aerocrine, grants and personal fees from AstraZeneca, grants and personal fees from Boehringer Ingelheim, grants and personal fees from Grifols, grants and personal fees from GlaxoSmithKline, grants and personal fees from Novartis, grants and personal fees from Trudell, outside the submitted work.

Acknowledgments

The authors thank the members of the Meakins-Christie Laboratories as well as the Respiratory Epidemiology and Clinical Research Unit. We would like to acknowledge the help of all staff and students involved in the study especially Hussein Traboulsi and Noof Aloufi.

Additional information

Funding

The project was funded by the Respiratory Health Network of the FRQS; Meakins-Christie Laboratories Collaborative Research Graduate Studentship Award, Research Institute of McGill University Health Center. The funders had no role in the study design, data collection, and analysis, or preparation of the manuscript.