Objective We investigated the effects of chronic waterpipe (WP) smoke on pulmonary function and immune response in a murine model using a research-grade WP and the effects of acute exposure on the regulation of immediate-early genes (IEGs).
Methods WP smoke was generated using three WP smoke puffing regimens based on the Beirut regimen. WP smoke samples generated under these puffing regimens were quantified for nicotine concentration. Mice were chronically exposed for 6 months followed by assessment of pulmonary function and airway inflammation. Transcriptomic analysis using RNAseq was conducted after acute exposure to characterise the IEG response. These biomarkers were then compared with those generated after exposure to dry smoke (without water added to the WP bowl).
Results We determined that nicotine composition in WP smoke ranged from 0.4 to 2.5 mg per puffing session. The lung immune response was sensitive to the incremental severity of chronic exposure, with modest decreases in airway inflammatory cells and chemokine levels compared with air-exposed controls. Pulmonary function was unmodified by chronic WP exposure. Acute WP exposure was found to activate the immune response and identified known and novel IEG as potential biomarkers of WP exposure.
Conclusion Chronic exposure to WP smoke leads to immune suppression without significant changes to pulmonary function. Transcriptomic analysis of the lung after acute exposure to WP smoke showed activation of the immune response and revealed IEGs that are common to WP and dry smoke, as well as pools of IEGs unique to each exposure, identifying potential biomarkers specific to WP exposure.
- Smoking Caused Disease
- Non-cigarette tobacco products
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Contributors SB, TS and HRR-C contributed to the conception of the work. HRR-C and TS contributed to the experimental design, implementation, data analysis, data collection and data interpretation. HRR-C, TS, JL and SB contributed to drafting of the paper. VV contributed to RNAseq experiment. BP contributed to computational reduction of RNAseq data and statistical validation of differentially expressed genes. JL, WM, IS and JE contributed to pulmonary function. MCB provided guidance on use of the research-grade WP and manuscript review. YCC, JW and JE contributed to all mice-related activities including mice exposure and organ collection.
Funding This work was supported by the National Institutes of Health under award numbers R01HL134149 (SB) and 3U01ES026721-02S1 (HRR-C).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This study was approved by the Animal Care and Use Committee (IACUC) at Johns Hopkins University. All animal experiments (methodology and procedures) were performed according to the recommendations and guidelines of the IACUC.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request.
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