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Comparative Study
. 2018 Nov;27(Suppl 1):s26-s29.
doi: 10.1136/tobaccocontrol-2018-054317. Epub 2018 Sep 5.

Cytotoxic effects of heated tobacco products (HTP) on human bronchial epithelial cells

Noel J Leigh  1 , Phillip L Tran  1 , Richard J O'Connor  1 , Maciej Lukasz Goniewicz  1
Affiliations
Comparative Study

Cytotoxic effects of heated tobacco products (HTP) on human bronchial epithelial cells

Noel J Leigh et al. Tob Control. 2018 Nov.

Abstract

Background: Heated tobacco product(s) (HTP), also called heat-not-burn products, are a re-emerging class of tobacco products that purport to reduce health risk compared with smoking combustible tobacco products. This study examined the potential toxic effects of inhaling emissions from an HTP in comparison with electronic and combustible tobacco cigarettes.

Methods: Inhalation toxicity of HTP (IQOS; tobacco flavour), e-cigarette (MarkTen; tobacco flavour) and tobacco cigarette (Marlboro Red) was examined in vitro using an air-liquid interface with human bronchial epithelial cells (H292). Cells were exposed directly to 55 puffs from the e-cigarette, 12 puffs from the HTP and 8 puffs from the tobacco cigarette to equilibrate nicotine delivery to the cells across products. Cytotoxicity was measured using neutral red uptake and trypan blue assays. Cytotoxic effects of each tested product (HTP, e-cigarette and tobacco cigarette) were compared with an air control. Release of inflammatory markers (cytokines) was measured using ELISA.

Results: The HTP showed higher cytotoxicity compared with the air controls using the neutral red assay. The HTP also showed higher cytotoxicity than the e-cigarette, but lower cytotoxicity than the combustible cigarettes using the same assay. A significant increase in cytokines levels, compared with air controls, was observed postexposure to tobacco smoke but not to emissions from HTP or e-cigarette aerosol.

Discussion: Using limited cytotoxic measures, the HTP showed reduced cytotoxicity relative to a combustible cigarette but higher toxicity than an e-cigarette. More comprehensive testing is needed to determine long-term effects of inhaling emissions from HTP.

Keywords: nicotine; non-cigarette tobacco products; toxicology.

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Conflict of interest statement

Competing interests: MLG reports grants from and served as an advisory board member to pharmaceutical companies that manufacture smoking cessation drugs. RJO was a member of the FDA Tobacco Products Scientific Advisory Committee which considered Philip Morris International’s modified risk application for IQOS in January 2018. Other authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Metabolic activity (neutral red assay) from H292 bronchial epithelial cells directly exposed using an air–liquid interface to emissions from heated tobacco product (HTP), e-cigarette, combustible tobacco cigarette and air (controls). Emissions were generated from a MarkTen electronic cigarette (55 puffs), IQOS HTP (12 puffs/heetstick) and Marlboro Red combustible cigarette (eight puffs/cigarette). *Significant difference compared with the air control (p<0.05). #Significant difference compared with IQOS product (p<0.05).
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