Development Of A Systems Toxicology Approach And Its Application To Quantify The Biological Impact Of Tobacco Smoke In Vitro And In Vivo

Cigarette consumption causes serious diseases. Philip Morris International R&D is focused on the development of alternatives to conventional cigarettes with the potential to reduce the risk of developing smoking-related diseases. The development of such Modified Risk Tobacco Products (MRTP) follows three objectives.Firstly, the product must generate an aerosol with massively reduced amounts of harmful constituents. This can be achieved for instance by heating instead of burning tobacco.Secondly, the product must remain sufficiently attractive to current smokers for them to switch from conventional cigarettes.Finally, it must be demonstrated that MRTPs have the potential to reduce the risk of developing smoking-related diseases, compared to continued cigarette consumption and benchmarked against smoking cessation, which remains the most effective disease risk reduction modality.To address the latter objective, we are developing novel assessment methods which include the use of organotypic (3-dimensional) cultures of respiratory tract epithelia (e.g., bronchial, buccal, gingival and nasal) which can be exposed in vitro at the air-liquid interface to Cigarette Smoke (CS) and MRTP aerosol. In this context, we developed a whole smoke exposure system in collaboration with Vitrocell® Systems (Waldkirch, Germany). This device allows the simultaneous exposure of 48 Transwell inserts under controlled humidity and temperature conditions. This exposure setup enables a variety of exposure regimens (e.g., acute exposure, repeated doses, smoking cessation, switching between test atmospheres) to be applied in our in vitro studies and may eventually help reduce the need for animal experiments. Using this Vitrocell® System, we studied how human bronchial epithelial cells, differentiated into a pseudo-stratified epithelium, respond to a single CS exposure at the transcriptomic level. We then compared these gene expression signatures with those derived from bronchial cells obtained from smokers and non-smokers through bronchial brushing. We observed that the biological network perturbations of both the organotypic cultures and the freshly obtained primary cells are very similar. These results demonstrate that the human organotypic cultures of the bronchial epithelium adequately reproduce the mechanistic effects of CS on human bronchial cells. Therefore, we propose to use such organotypic cultures to quantitatively compare the perturbation of disease-associated biological networks caused by CS and MRTP aerosols.