Document Type


Peer Reviewed


Publication Date


NLM Title Abbreviation

Respir Res

Journal/Book/Conference Title

Respiratory research

PubMed ID


DOI of Published Version


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BACKGROUND: Smoking is a leading cause of respiratory infections worldwide. Tobacco particulate matter disrupts iron homeostasis in the lungs and increases the iron content in the airways of smokers. The airway epithelia secrete lactoferrin to quench iron required for bacteria to proliferate and cause lung infections. We hypothesized that smokers would have increased bacterial growth and biofilm formation via iron lactoferrin imbalance.

METHODS: We collected bronchoalveolar lavage (BAL) samples from non-smokers and smokers. We challenged these samples using a standard inoculum of Staphylococcus aureus and Pseudomonas aeruginosa and quantified bacterial growth and biofilm formation. We measured both iron and lactoferrin in the samples. We investigated the effect of supplementing non-smoker BAL with cigarette smoke extract (CSE) or ferric chloride and the effect of supplementing smoker BAL with lactoferrin on bacterial growth and biofilm formation.

RESULTS: BAL from smokers had increased bacterial growth and biofilm formation compared to non-smokers after both S. aureus and P. aeruginosa challenge. In addition, we found that samples from smokers had a higher iron to lactoferrin ratio. Supplementing the BAL of non-smokers with cigarette smoke extract and ferric chloride increased bacterial growth. Conversely, supplementing the BAL of smokers with lactoferrin had a concentration-dependent decrease in bacterial growth and biofilm formation.

CONCLUSION: Cigarette smoking produces factors which increase bacterial growth and biofilm formation in the BAL. We propose that smoking disrupts the iron-to-lactoferrin in the airways. This finding offers a new avenue for potential therapeutic interventions to prevent respiratory infections in smokers.


iron-lactoferrin imbalance, Staphylococcus aureus, Pseudomonas aeruginosa, smoking, bronchoalveolar lavage, biofilm, epithelia, pediatrics, pulmonology


This project was made possible by: The Center for Health Effects of Environmental Contamination Seed Grants: FY 2010, the National Center for Research Resources, a part of the National Institutes of Health (NIH): UL1RR024979 and KO1HL080966, National Institute of Environmental Health Sciences: P30 ES005605 and National Institute of Allergy and Infectious Diseases: NO1-AI-30040-01.

Journal Article Version

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Published Article/Book Citation

Respir Res. 2018 Mar 10;19(1):42. doi: 10.1186/s12931-018-0743-x.


© The Author(s) 2018

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