Evaluation of a Reconstructed Human Oral Buccal Tissue Model as a Testing Platform for Determining the Oral Irritation Potential of Tobacco Products

There is an increasing need by the tobacco industry to evaluate the irritation and inflammation potential of tobacco products to support product development goals, for sound product stewardship, and likely regulatory safety tests. The use of in vitro human cell and tissue-based test methods to replace in vivo animal models addresses the need for more human-relevant predictive tools, and is consistent with many corporate animal welfare policies. Although monolayer cell-based cytotoxicity and cytokine expression assays have been used, three-dimensional tissue constructs provide distinct advantages since tissue exposures and pharmacokinetics more closely resemble the in vivo events. In this study, we evaluated a reconstructed human oral buccal model for determining the oral irritation of oral tobacco products. A dilution series of tobacco extracts were applied topically onto the EpiOral™ reconstructed human oral buccal model (Cat no. ORL-200) (MatTek Corporation, Ashland, MA) for various exposure times (ranging from 2 to 16 hours) to estimate oral irritation potential based upon reduction in cell viability and the synthesis/release of the inflammatory mediators IL-1α and IL-8. We determined tobacco extract concentration-related increases in cytotoxicity for the highest tobacco extract concentrations. We also found that increases in IL-1α release (up to 19-fold) generally correlated with the cytotoxicity increases. Exposure time related increases in IL-8 release were generally observed in tissues treated with the three lower tobacco extract concentrations where relative viabilities were sufficiently high to allow for secondary cytokine production, but at the highest tobacco extract concentrations IL-8 release were below control levels where cytotoxic effects inhibited the cells’ ability to synthesize proteins. These results demonstrate the utility of reconstructed human epithelial models for evaluating the irritation potential of tobacco products. To expand upon this utility, we propose to apply these general methods for determining cytotoxicity and inflammatory cytokine profiles to evaluating inflammation responses in reconstructed human airway tissue models exposed to combustible tobacco product extracts, particulate matter, and whole smoke.

ORL-200, Oral Irritation, MTT, IL-1a, IL-8, inflammatory cytokines

Saliva (artificial), tobacco extracts, mouthwash, toothpaste