Tobacco-Related Disease Research Program

Introduction: Recent guideline changes for lung cancer screening with low-dose computed tomography recommend smoking cessation interventions be done in parallel with screening. The purpose of this study is to determine the post-guideline rates of smoking cessation interventions among patients eligible and ineligible for lung cancer screening.

Methods: Using electronic health records collected from a large ambulatory care system in northern California between 2010 and 2017, authors identified new patients who were current smokers aged 55–80 years visiting a primary care provider, and grouped patients into lung cancer screening–eligible heavy smokers, screening-ineligible moderate smokers, and screening-ineligible light smokers. Screening-eligible smokers versus screening-ineligible smokers were compared in receipt of smoking cessation interventions before (2010–2013) and after (2014–2017) the guideline change, overall and by intervention type (formal counseling, informal counseling, pharmacotherapy) using hierarchical generalized linear models. Analyses were conducted in 2018–2019.

Results: After the guideline change, the likelihood of receiving any smoking cessation intervention (OR=1.44, 95% CI=1.28, 1.61, p<0.05), informal counseling (OR=1.29, 95% CI=1.15, 1.46, p<0.05), and pharmacotherapy (OR=1.24, 95% CI=1.02, 1.50, p<0.05) during a new patient visit significantly increased, with the increase not varying by level of smoking. For formal counseling, the post-guideline increase was greater for screening-eligible heavy smokers (OR=3.15, 95% CI=1.18, 8.36, p<0.05) and moderate smokers (OR=3.58, 95% CI=1.29, 9.95, p<0.05) relative to light smokers.

Conclusions: Smoking cessation interventions increased after new lung cancer screening guidelines. Given the sizable adverse impacts of smoking on morbidity and mortality, small increases in implementation of smoking cessation interventions could have substantial public health benefits.

Electronic cigarettes (E-cig) use is increasing rapidly, particularly among youths. Animal models for E-cig exposure with pharmacokinetics resembling human E-cig users are lacking. We developed an E-cig aerosol exposure system for rodents and a chronic intermittent delivery method that simulates E-cig users who vape episodically during wakefulness and abstain during sleep. Mice were exposed to E-cig in a programmed schedule at very low, low, medium, or high doses defined by duration of each puff, number of puffs per delivery episode and frequency of episodes in the dark phase of a 12/12-h circadian cycle for 9 consecutive days. The plasma nicotine/cotinine levels and their time courses were determined using LC/MS-MS. We assessed the body weight, food intake and locomotor activity of Apolipoprotein E null (ApoE-/-) mice exposed to chronic intermittent E-cig aerosol. Plasma nicotine and cotinine levels were positively correlated with exposure doses. Nicotine and cotinine levels showed a circadian variation as they increased with time up to the maximum nicotine level of 21.8 ± 7.1 ng/mL during the daily intermittent E-cig exposure in the 12-h dark phase and then declined during the light phase when there was no E-cig delivery. Chronic E-cig exposure to ApoE-/- mice decreased body weight, food intake and increased locomotion. Our rodent E-cig exposure system and chronic intermittent exposure method yield clinically relevant nicotine pharmacokinetics associated with behavioral and metabolic changes. The methodologies are essential tools for in vivo studies of the health impacts of E-cig exposure on CNS, cardiovascular, pulmonary, hepatic systems, metabolism and carcinogenesis.

Electronic cigarettes (e-cigarettes), also known as electronic nicotine delivery systems, are a popular alternative to conventional nicotine cigarettes, both among smokers and those who have never smoked. In spite of the widespread use of e-cigarettes and the proposed detrimental cardiac and atherosclerotic effects of nicotine, the effects of e-cigarettes on these systems are not known. In this study, we investigated the cardiovascular and cardiac effects of e-cigarettes with and without nicotine in apolipoprotein-E knockout (ApoE^-/-) mice. We developed an e-cigarette exposure model that delivers nicotine in a manner similar to that of human e-cigarettes users. Using commercially available e-cigarettes, bluCig PLUS, ApoE^-/- mice were exposed to saline, e-cigarette without nicotine [e-cigarette (0%)], and e-cigarette with 2.4% nicotine [e-cigarette (2.4%)] aerosol for 12 wk. Echocardiographic data show that mice treated with e-cigarette (2.4%) had decreased left ventricular fractional shortening and ejection fraction compared with e-cigarette (0%) and saline. Ventricular transcriptomic analysis revealed changes in genes associated with metabolism, circadian rhythm, and inflammation in e-cigarette (2.4%)-treated ApoE^-/- mice. Transmission electron microscopy revealed that cardiomyocytes of mice treated with e-cigarette (2.4%) exhibited ultrastructural abnormalities indicative of cardiomyopathy. Additionally, we observed increased oxidative stress and mitochondrial DNA mutations in mice treated with e-cigarette (2.4%). ApoE^-/- mice on e-cigarette (2.4%) had also increased atherosclerotic lesions compared with saline aerosol-treated mice. These results demonstrate adverse effects of e-cigarettes on cardiac function in mice.NEW & NOTEWORTHY The present study is the first to show that mice exposed to nicotine electronic cigarettes (e-cigarettes) have decreased cardiac fractional shortening and ejection fraction in comparison with controls. RNA-seq analysis reveals a proinflammatory phenotype induced by e-cigarettes with nicotine. We also found increased atherosclerosis in the aortic root of mice treated with e-cigarettes with nicotine. Our results show that e-cigarettes with nicotine lead to detrimental effects on the heart that should serve as a warning to e-cigarette users and agencies that regulate them.

The use of electronic nicotine delivery systems (ENDS), also known as e-cigarettes, with a variety of e-liquids/e-juices, is increasing at an alarming rate among adolescents who do not realize the potential harmful health effects. This study examines the harmful effects of ENDS on the liver. Apolipoprotein E null (ApoE-/-) mice on a western diet (WD) were exposed to saline or ENDS with 2.4% nicotine aerosol for 12 weeks using our mouse ENDS exposure model system, which delivers nicotine to mice and leads to equivalent serum cotinine levels found in human cigarette users. ApoE-/- mice on a WD exposed to ENDS exhibited a marked increase in hepatic lipid accumulation compared with ApoE-/- on a similar diet exposed to saline aerosol. The detrimental effects of ENDS on hepatic steatosis were associated with significantly greater oxidative stress, increased hepatic triglyceride levels, and increased hepatocyte apoptosis, independent of adenosine monophosphate-activated protein kinase signaling. In addition, hepatic RNA sequencing analysis revealed that 433 genes were differentially expressed in ENDS-exposed mice on WD compared with saline-exposed mice. Functional analysis indicates that genes associated with lipid metabolism, cholesterol biosynthesis, and circadian rhythm were most significantly altered in the liver in response to ENDS. Conclusion: These results demonstrate profound adverse effects of ENDS on the liver. This is important information for regulatory agencies as they regulate ENDS.

Effective community engagement in T₃-T₄ research is widespread, however, similar stakeholder involvement is missing in T₁-T₂ research. As part of an effort to embed community stakeholders in T₁-T₂ research, an academic community partnered team conducted discussion groups with researchers to assess perspectives on (1) barriers/challenges to including community stakeholders in basic science, (2) skills/training required for stakeholders and researchers, and (3) potential benefits of these activities. Engaging community in basic science research was perceived as challenging but with exciting potential to incorporate "real-life" community health priorities into basic research, resulting in a new full-spectrum translational research model.

The prevalence of electronic cigarette (e-cigarettes) use has rapidly increased worldwide. Use of tobacco products has been associated with DNA damage and metabolic syndrome. Using Apolipoprotein E knockout (ApoE^-/-) mice on a western diet (WD), a mouse model of non-alcoholic fatty liver disease (NAFLD), we recently demonstrated that nicotine in e-cigarettes activates hepatocyte apoptosis, and causes hepatic steatosis. This study examines the harmful effects of e-cigarettes on the liver with a special emphasis on DNA damage and mitochondrial dysfunction. ApoE^-/- mice were exposed to saline, e-cigarettes without nicotine or e-cigarettes with 2.4% nicotine for 12 weeks using our newly developed mouse e-cigarette exposure model system that delivers nicotine to mice leading to equivalent serum cotinine levels found in human cigarette users. Mice exposed to e-cigarette (2.4% nicotine) had increased apurinic/apyrimidinic (AP) sites, a manifestation of DNA damage. Additionally, e-cigarette (2.4% nicotine) produced a decrease in NAD+/NADH ratio and increased oxidative stress in hepatic cells, in comparison with saline and e-cigarette (0%). Western blot analysis showed that mice treated with e-cigarette (2.4% nicotine) had increased poly (ADP ribose) polymerase (PARP1) activity associated with reduced levels of Sirtuin 1 (SIRT1). Furthermore, mitochondrial DNA mutations and PTEN-induced kinase 1 (PINK1) were increased in mice treated with e-cigarette (2.4% nicotine). Transmission electron microscopy revealed that hepatocytes of mice treated with e-cigarette (2.4% nicotine) exhibited increased vacuolization of the mitochondria and a reduction in cellular organelles. These results demonstrate the adverse effects of e-cigarettes exposure leading to NAD+ deficiency which may suggest a mechanistic link between e-cigarette-induced hepatic DNA damage and mitochondrial dysfunction.