Nearly 16% of US young adults ages 18?24 report smoking cigars and a recent review documents growing evidence linking this product to lung cancer, coronary heart disease, aortic aneurysm and COPD. Similarly, epidemiological studies link waterpipe tobacco to these same diseases. To date, there are few studies characterizing these tobacco aerosols with respect to toxicant chemicals, and limited information regarding effects on target cells with respect to cytotoxicity, genotoxicity, inflammation, and immune responses. Importantly, no comparative dose response studies to cigarettes have been conducted to study these endpoints, a research gap that is imperative to address for providing pharmacodynamic outcomes for these addictive nicotine-containing products. Our research will allow for establishment of strong evidence- based policies to inform the public of their hazardous properties.
The specific aims and research strategy derive from these research gaps and address two of the scientific domains in the RFA, toxicity and health effects. As mandated by the FDA, the studies are not mechanistic, but are designed to compare responses and effects at the cellular level across tobacco products (cigarettes, cigarillos, and hookah). The central hypothesis of this project is that cigarillo and hookah tobacco products will show significantly greater toxicant properties and predicted health effects when compared to cigarettes. Building on more than two decades of experience in characterizing the physical and chemical properties of complex aerosols, Aim 1 will provide the most comprehensive characterization to date for hazardous chemicals linked to cancer and cardiopulmonary diseases in aerosols from eight common hookah tobacco products. The extensive dose response characterization of the TPM generated from aerosols of these products using standardized cytotoxicity, mutagenicity, and genotoxicity assays will also provide key insight regarding the potency of these products for causing toxicity and harm relative to our studies just completed for cigarettes and cigarillos. Through a battery of short-term assays and biomarkers (cytokines, DNA adducts), Aim 2 will critically evaluate complete and fractionated (particles and gas only) aerosols generated from cigarettes, cigarillos, and hookah products in lung epithelial cells, cardiac cells, and endothelial cells. A cumulative hazard score for each product will be derived.
Aim 3 focuses on adaptive responses of lung epithelial cells in response to treatment of cells for 4-wk with complete aerosols from one each of these tobacco products. Outcomes from results will include changes in cytokine levels and pathway alterations that may impact immune response, signaling, invasion, and growth. These studies should inform generalized responses of the large and small airway epithelium that could demonstrate a pro-inflammatory environment and/or altered immune signaling documented in the literature to be associated with mucous hypersecretion and/or emphysema.
Project Relevance This study will evaluate the toxicant properties and health effects of cigarillo and hookah tobacco products through three integrated aims with respect to toxicant chemicals; cytotoxicity, genotoxicity, inflammation and immune responses to derive a hazard score for each product. Studying effects on lung epithelial, cardiac, and endothelial cells will provide outcomes to support strong evidence-based policies for informing the public and substantiating new regulatory policies regarding the hazardous properties of cigarillo and hookah products with respect to cardiovascular and respiratory effects.