Core 3 - Biomarkers and Product Evaluation

ABSTRACT – CORE 003: Biomarkers and Product Evaluation Core The goal of the Biomarkers and Product Evaluation Core is to facilitate the research proposed in Project MARVEL by providing data on biomarkers of exposure and biological effects as well as to characterize commonly used vaping products. These data will allow individual projects to achieve their Specific Aims. The measurement of toxicant and carcinogen metabolites in body fluids of people who use tobacco products is the accepted method for objective assessment of exposure to these products. Total nicotine equivalents (TNE), the sum of nicotine and six nicotine metabolites accounts for >85% of the nicotine dose, is a well-established biomarker of nicotine exposure. The primary pathway of nicotine metabolism is cytochrome P450 2A6 (CYP2A6)-catalyzed C-oxidation, which leads to the formation of cotinine. Cotinine is further metabolized, also by CYP2A6, to 3'-hydroxycotinine. The ratio of 3'-hydroxycotinine to cotinine in plasma or saliva (referred to as the NMR) is an excellent phenotypic measure of CYP2A6 activity, and may be used to characterize individual differences in nicotine metabolism. Urinary concentrations of the acrylonitrile mercapturic acid, 2-cyanoethyl- mercapturic acid (CEMA) is from 100 to more than 400 times higher in smokers compared to non-smokers and can be used to distinguish combustible from non-combustible tobacco use with sensitivity and specificity >99%. The mercapturic acids of acrolein, crotonaldehyde, and benzene, 3-hydroxypropyl-mercapturic acid (3HPMA), 3-hydroxy-1-methylpropylmercpturic acid (HMPMA), S-phenylmercapturic acid (SPMA) can be used to quantify exposure to volatile toxicants in cigarette and e-cigarette users. Oxidative damage can be measured with urinary 8-iso-PGF2α, an F2-isoprostane and elevated PGE-M, a prostaglandin-E2 metabolite is a biomarker of inflammation. Vaping products may vary widely in their fluid constituents and generated aerosol. The Core will analyze saliva samples from Lab Study participants for cotinine and the NMR. Urine samples from participants attending lab-based assessments will be analyzed for TNE, mercapturic acids, 8-iso-PGF2α and .PGE-M. The Core will also determine e-liquid constituents and generated aerosol yield of the most abundantly used e-cigarettes among the participants of this study. The Specific Aims are to: 1) Characterize individual differences in nicotine metabolism and exposure in participants in the cohort study; 2) Quantify exposure to other constituents found in tobacco products and systemic indices of oxidative stress and inflammation in participants of the lab-based assessments; 3) Characterize toxic constituents in e-liquids and aerosol. The Core is housed at the University of Minnesota which provides state-of-the-art expertise and technology for the quantitation of these biomarkers, and the constituents of e-cigarettes. The University of Minnesota is widely recognized as one of the leading academic centers for this research. Objective verification of product characteristics, user exposure, and biological effects is a critically important component of robust research on the health effects of tobacco products.