Assessing Multiple Evidence Streams to Decide on Confidence for Identification of Post-Translational Modifications, within and Across Data Sets.

Phosphorylation is a post-translational modification of great interest to researchers due to its relevance in many biological processes. LC-MS/MS techniques have enabled high-throughput data acquisition, with studies claiming identification and localization of thousands of phosphosites. The identification and localization of phosphosites emerge from different analytical pipelines and scoring algorithms, with uncertainty embedded throughout the pipeline. For many pipelines and algorithms, arbitrary thresholding is used, but little is known about the actual global false localization rate in these studies. Recently, it has been suggested to use decoy amino acids to estimate global false localization rates of phosphosites, among the peptide-spectrum matches reported. Here, we describe a simple pipeline aiming to maximize the information extracted from these studies by objectively collapsing from peptide-spectrum match to the peptidoform-site level, as well as combining findings from multiple studies while maintaining track of false localization rates. We show that the approach is more effective than current processes that use a simpler mechanism for handling phosphosite identification redundancy within and across studies. In our case study using eight rice phosphoproteomics data sets, 6368 unique sites were confidently identified using our decoy approach compared to 4687 using traditional thresholding in which false localization rates are unknown.

A randomised study to assess the nicotine pharmacokinetics of an oral nicotine pouch and two nicotine replacement therapy products.

Nicotine replacement therapies (NRTs) are intended for short-term use to help cigarette smokers to quit. Some smokers find NRTs ineffective or seek a more satisfactory source of nicotine. Tobacco-free oral nicotine pouch (NP) products have emerged as a potential reduced risk product compared with cigarettes and other tobacco products. In a randomised crossover clinical study, thirty-four healthy adult smokers were enrolled and their nicotine Cmax and AUC0-T determined for three 4 mg nicotine products (NP, gum, lozenge) under fasting conditions. The NP, lozenge and gum mean Cmax values were 8.5, 8.3 and 4.4 ng/mL, AUC0-T values were 30.6, 31.5 and 14.3 ng*h/mL, respectively. The NP showed similar nicotine bioavailability to the lozenge (p = 0.6526 (Cmax), p = 1.0000 (AUC0-T)), and superior bioavailability to the gum (p < 0.0001 for Cmax and AUC0-T). Compared with the lozenge, the NP demonstrated greater product satisfaction with a higher number of positive responses to subjective satisfaction questions. All products were judged to be well-tolerated; the incidence of minor adverse events was lower for the NP (18.2%) than the lozenge (33.3%) or gum (18.8%). In summary, NPs may provide smokers with a more satisfying alternative nicotine source as compared to the reference NRTs.Study Registry/Registered Trial No: ISRCTN/ISRCTN65708311.

A Randomised Study to Investigate the Nicotine Pharmacokinetics of Oral Nicotine Pouches and a Combustible Cigarette.

BACKGROUND AND OBJECTIVES: Nicotine pouches (NPs) are a relatively new type of oral smokeless tobacco-free nicotine product. Currently, few data are available on the nicotine pharmacokinetics or subjective effects of NP use. The objective of this study was to determine and compare the pharmacokinetics of nicotine absorption into the blood from different NP variants and a combustible cigarette. METHODS: In a randomised, controlled, crossover clinical study, nicotine pharmacokinetics and subjective effects were compared among commercially available NPs (five different brands; 6-10 mg nicotine/pouch) and a combustible cigarette. During an 8-day confinement period, 35 healthy adult participants who were current dual users of snus and combustible cigarettes used one study product each day for a defined period following overnight nicotine abstinence. RESULTS: Nicotine maximum plasma concentration (Cmax) and area under the plasma concentration-time curve between 0 and 6 h (AUC0-6h) were significantly greater for the Lyft 10 mg NP than for the cigarette (both p < 0.0001), while the other NPs had Cmax and AUC0-6h values that were either greater than or similar to those of the cigarette. Plasma nicotine concentration was not associated with the nicotine contents of the NPs. Time to reach maximum plasma concentration (Tmax) was higher for all NPs (60-65 min) than for the cigarette (7 min). Regarding subjective effects, liking and intent to use product again scores were higher for the cigarette than for any NP and were lowest for the NP with the lowest nicotine content. CONCLUSIONS: This study provides important insight into nicotine pharmacokinetics and subjective effects during NP use, and demonstrates that NPs can provide nicotine in amounts sufficient to replicate cigarette smokers' nicotine uptake following a switch from conventional cigarettes to these potentially less harmful NP products. Further studies are required to ascertain how physical characteristics of NPs other than nicotine content may affect nicotine delivery, pharmacokinetics and subjective responses. ISRCTN CLINICAL TRIAL REGISTRY: ISRCTN17828518.

Investigating the Health Effects of 3 Coexisting Tobacco-Related Products Using System Dynamics Population Modeling: An Italian Population Case Study.

With the proliferation of tobacco products, there might be a need for more complex models than current two-product models. We have developed a three-product model able to represent interactions between three products in the marketplace. We also investigate if using several implementations of two-product models could provide sufficient information to assess 3 coexisting products. Italy is used as case-study with THPs and e-cigarettes as the products under investigation. We use transitions rates estimated for THPs in Japan and e-cigarettes in the USA to project what could happen if the Italian population were to behave as the Japanese for THP or USA for e-cigarettes. Results suggest that three-product models may be hindered by data availability while two product models could miss potential synergies between products. Both, THP and E-Cigarette scenarios, led to reduction in life-years lost although the Japanese THP scenario reductions were 3 times larger than the USA e-cigarette projections.

Changes in biomarkers after 180 days of tobacco heating product use: a randomised trial.

The aim of this study was to investigate whether biomarkers of exposure (BoE) and potential harm (BoPH) are modified when smokers switch from smoking cigarettes to exclusive use of a tobacco heating product (THP) in an ambulatory setting. Participants in this randomised, controlled study were healthy volunteer smokers assigned either to continue smoking or switch to a THP, and a control group of smokers who abstained from cigarette smoking. Various BoE and BoPH related to oxidative stress, cardiovascular and respiratory diseases, and cancer were assessed at baseline and up to 180 days. In continuing smokers, BoE and BoPH remained stable between baseline and day 180, while THP users' levels of most BoE reduced significantly, becoming similar to those in controls abstaining from cigarette smoking. Also at 180 days, significant changes in numerous BoPH, including total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, 8-epi-prostaglandin F2α type III, fractional concentration of exhaled nitric oxide and white blood cell count, were directionally consistent with lessened health impact. Our findings support the notion that the deleterious health impacts of cigarette smoking may be reduced in smokers who completely switch to using THPs.

A randomized controlled study in healthy participants to explore the exposure continuum when smokers switch to a tobacco heating product or an E-cigarette relative to cessation.

BACKGROUND: Cigarette smoking is associated with a number of diseases, such as cancer and cardiovascular diseases. Recently, there has been an increase in the use of electronic cigarettes (ECs) and tobacco-heating products (THPs) as an alternative to cigarettes, which may reduce the health burden associated with smoking. However, an exposure continuum when smokers switch to ECs or THPs compared to complete smoking cessation is not well established. METHODS: 148 healthy smokers were randomized to either continue smoking cigarettes, switch to using the glo THP or a prototype EC, or completely quit any nicotine or tobacco product use for 5 days, after a 2-day baseline period. During this study breath and 24-h urine samples were collected for Biomarker of Exposure (BoE) analysis. RESULTS: After a 5-day switching period BoE levels showed a substantial significant decrease in levels from baseline in the groups using the glo THP, the prototype EC, and having quit all nicotine and tobacco use. On an exposure continuum, smokers who completely quit nicotine had the lowest levels of assessed BoEs, followed by those who switched to the EC and then those who switched to glo THP use. Participants who continued to smoke had the highest levels of BoEs. CONCLUSIONS: THP or EC use over a 5-day period resulted in significant reductions in exposure to smoke toxicants, in some cases to levels similar to those for nicotine cessation. These results show that on an exposure continuum, nicotine cessation gives the greatest reduction in exposure to tobacco smoke toxicants, closely followed by the EC and the glo THP. These significant reductions in exposure to toxicants suggest that the glo THP and EC have the potential to be Reduced Risk Products. STUDY REGISTRATION: ISRCTN80651909.

The development of an in vitro 3D model of goblet cell hyperplasia using MUC5AC expression and repeated whole aerosol exposures.

Goblet cell hyperplasia and overproduction of airway mucin are characteristic features of the lung epithelium of smokers and COPD patients. Tobacco heating products (THPs) are a potentially less risky alternative to combustible cigarettes, and through continued use solus THPs may reduce smoking-related disease risk. Using the MucilAir™ in vitro lung model, a 6-week feasibility study was conducted investigating the effect of repeated cigarette smoke (1R6F), THP aerosol and air exposure. Tissues were exposed to nicotine-matched whole aerosol doses 3 times/week. Endpoints assessed were dosimetry, tight-junction integrity, cilia beat frequency (CBF) and active area (AA), cytokine secretion and airway mucin MUC5AC expression. Comparison of incubator and air exposed controls indicated exposures did not have a significant effect on the transepithelial electrical resistance (TEER), CBF and AA of the tissues. Cytokine secretion indicated clear differences in secretion patterns in response to 1R6F and THP exposure. 1R6F exposure resulted in a significant decrease in the TEER and AA (p=0.000 and p=0.000, respectively), and an increase in MUC5AC positive cells (p=0.002). Repeated THP exposure did not result in a significant change in MUC5AC positive cells. This study demonstrates repeated cigarette smoke whole aerosol exposure can induce these morphological changes in vitro.

Changes in Biomarkers of Exposure on Switching From a Conventional Cigarette to the glo Tobacco Heating Product: A Randomized, Controlled Ambulatory Study.

INTRODUCTION: Tobacco heating products (THPs) generate lower machine yields of toxicants compared to those found in conventional cigarette smoke. During use, these products are likely to expose users to lower levels of particulate matter and harmful and potentially harmful compounds compared with smoking cigarettes. AIMS AND METHODS: This randomized, controlled study is investigating whether biomarkers of exposure (BoE) to smoke toxicants are reduced when smokers switch from smoking cigarettes to using the glo THP in a naturalistic, ambulatory setting. Control groups include smokers who are abstaining from cigarette smoking and never-smokers. At a baseline study visit, 24-hour urine samples and spot blood samples were taken for BoE analysis, and exhaled carbon monoxide was also measured. N-(2-cyanoethyl) valine (CEVal) was used as a marker of compliance in subjects asked to refrain from combustible cigarette smoking. Subjects are being followed up at periodic intervals for 360 days; this article presents data following a planned interim analysis at day 90. RESULTS: In continuing smokers, BoE remained stable between baseline (day 1) and day 90. In both per-protocol and CEVal-compliant analysis populations, reductions in BoE were observed in subjects switching to using glo or undergoing smoking cessation. These reductions were statistically significant for a number of BoE when switching to glo was compared with continued smoking. Furthermore, in both populations, reductions observed in subjects switching to using glo were comparable to those seen with smoking cessation and were also to levels similar to those seen in never-smokers. CONCLUSION: glo is a reduced-exposure tobacco product. IMPLICATIONS: This clinical study builds on a previous 5-day confinement study and demonstrates that when smokers switched from smoking combustible cigarettes to using the glo THP in a naturalistic, ambulatory setting, their exposure to tobacco smoke toxicants was significantly decreased. For most BoE examined, this was to the same extent as that seen when a control group of smokers ceased cigarette smoking, or even to levels seen in never-smoker controls. This indicates that glo is a reduced-exposure product with the potential to be a reduced-risk tobacco product, when used by smokers whose cigarette consumption is displaced completely. CLINICAL TRIAL REGISTRATION: ISRCTN81075760.

A randomised controlled single-centre open-label pharmacokinetic study to examine various approaches of nicotine delivery using electronic cigarettes.

Smokers who switch completely to e-cigarettes may reduce their relative risk of tobacco-related disease. Effective nicotine delivery from e-cigarettes is important in consumer acceptance. We assessed whether protonated nicotine and e-cigarette devices delivering greater aerosol mass increase nicotine delivery and product liking. A randomised controlled non-blinded eight-arm crossover study was used to assess plasma nicotine pharmacokinetics and product liking for two e-cigarettes (Vype ePen3 and Vype ePen) with various nicotine e-liquid formulations and a conventional cigarette among 24 healthy dual-users of cigarettes and e-cigarettes. Product use and puff count were also assessed. Results show that nicotine bioavailability was greater for Vype ePen3 with greater aerosol mass delivery than for Vype ePen (Cmax, p = 0.0073; AUC0-120 min, p = 0.0102). Protonated nicotine (18 mg/mL, medium protonation) e-liquid yielded higher nicotine bioavailability than unprotonated nicotine (18 mg/mL) e-liquid (Cmax, p = 0.0001; AUC0-120 min, p = 0.0026). There was no significant difference in Tmax between e-liquids. Nicotine bioavailability did not differ between nicotine benzoate formulation (30 mg/mL nicotine, high protonation) and combustible cigarettes (Cmax, p = 0.79; AUC0-120 min, p = 0.13). Vype ePen3 with protonated nicotine delivers nicotine more efficiently with the potential to increase product liking relative to earlier devices using unprotonated e-liquid.

Evaluation of a high-throughput in vitro endothelial cell migration assay for the assessment of nicotine and tobacco delivery products.

Endothelial cell migration is a critical process in the maintenance of healthy blood vessels. Impaired endothelial migration is reportedly associated with the development of cardiovascular diseases. Here, we report on the development of a 96-well in vitro endothelial migration assay for the purpose of comparative toxicological assessment of a novel THP relative to cigarette smoke, to be able to rapidly inform regulatory decision making. Uniform scratches were induced in confluent human umbilical vein endothelial cells using the 96-pin wound maker and exposed to 3R4F cigarette or THP aqueous extracts (AqE). Endothelial migration was recorded over 24 h, and the rate of wound closure calculated using mean relative wound density rather than migration rate as previously reported. This self-normalising parameter accounts for starting wound size, by comparing the density of the scratch to the outer region at each time-point. Furthermore, wound width acceptance criteria was defined to further increase the sensitivity of the assay. 3R4F and THP AqE samples were tested at comparable nicotine concentrations. 3R4F showed significant cytotoxicity and inhibition of wound healing whereas THP AqE did not show any response in either endpoint. This 96-well endothelial migration assay was suitably sensitive to distinguish combustible cigarette and THP test articles.

Results from a 2018 cross-sectional survey in Tokyo, Osaka and Sendai to assess tobacco and nicotine product usage after the introduction of heated tobacco products (HTPs) in Japan.

BACKGROUND: For novel tobacco products that potentially reduce the risk of tobacco harm, post-market surveillance is important to observe population usage and behaviours associated with everyday use. This pilot study was performed to examine the use of tobacco products in three Japanese urban regions. METHODS: This study was a cross-sectional epidemiological survey administered in Sendai, Tokyo and Osaka, Japan, from May 19th to June 25th, 2018. Participants were selected with a three-stage probability random sampling process that first identified primary sampling units, then households and finally individuals. Eligible participants were aged at least 20 years who were willing to participate after information about the study was provided. People younger than 20 years and those living in institutions were excluded. Questionnaires were paper based and administered door to door. RESULTS: Responses were obtained from 4154 participants. Sixty-five percent self-reported being never, 19% current and 16% former users of any tobacco product at the time of the survey. Combustible tobacco products (almost all being cigarette) were used most (16%) followed by HTPs (5%). In the categories of combustible tobacco users and HTP users, 70% and 16%, respectively, used these products exclusively. Dual use was reported by 11% of respondents. Compared with 12 months before the survey, 12% of sole combustible tobacco products users were using HTPs exclusively or as dual users and 6% had quit tobacco products completely; 94% of sole HTP users remained sole users and 4% had quit tobacco products completely; and amongst dual users 12% had reverted to exclusive use of combustible tobacco products, 14% had switched to sole use of HTPs and 4% had quit tobacco products completely. CONCLUSION: HTPs seem to be accepted as an alternative tobacco product amongst combustible tobacco users. Given complex findings for dual use, improved understanding of the motivations underlying this behaviour would be of interest.

Statistical analysis plan for "A randomised, controlled study to evaluate the effects of switching from cigarette smoking to using a tobacco heating product on health effect indicators in healthy subjects".

Tobacco harm reduction strategies aim to substitute smoking with potentially reduced risk products (PRRPs) such as e-cigarettes and tobacco-heating products (THPs). The health benefits of switching from smoking to PRRPs is unknown. A randomised controlled trial is being conducted to increase understanding of the health effects of switching from smoking to a THP in a 12-month long ambulatory study (ISRCTN81075760). Here we describe the study endpoints and the statistical analysis plan. Endpoints are divided into biomarkers of exposure (BoE) to tobacco smoke constituents and health effect indicators related to risk of lung cancer, cardiovascular and obstructive lung disease. These have been selected on the basis of extensive literature evidence. Three primary endpoints, augmentation index (risk factor for cardiovascular disease), total NNAL (linked to lung cancer) and 8-Epi-PGF2α type III (indicator of oxidative stress linked to various diseases), and multiple secondary endpoints will be analysed at 90, 180, and 360 days. Changes from baseline will be compared between study arms by specific contrasts in mixed models. Study wise multiple comparisons adjustments will be performed to account for multiplicity of timepoints and comparisons within timepoints. Generalisability of outcomes will be tested by a sensitivity analysis adjusting for age and gender. Importantly, an ancillary analysis will be performed to assess product compliance during the study based on plasma levels of CEVal, a surrogate marker for acrylonitrile exposure. The rationale underlying the selection of BoEs and health effect indicators, coupled with the statistical analysis plan will be central to understanding the potential health effects of replacing smoking with THP use for one year.

Changes in Biomarkers of Exposure on Switching From a Conventional Cigarette to Tobacco Heating Products: A Randomized, Controlled Study in Healthy Japanese Subjects.

BACKGROUND: Smoking is a leading cause of numerous human disorders including pulmonary disease, cardiovascular disease, and cancer. Disease development is primarily caused by exposure to cigarette smoke constituents, many of which are known toxicants. Switching smokers to modified risk tobacco products (MRTPs) has been suggested as a potential means to reduce the risks of tobacco use, by reducing such exposure. METHODS: This randomized, controlled study investigated whether biomarkers of toxicant exposure (BoE) were reduced when smokers switched from smoking combustible cigarettes to using a novel (glo™/THP1.0) or in-market comparator (iQOS/THS) tobacco heating product (THP). One hundred eighty Japanese smokers smoked combustible cigarettes during a 2-day baseline period, followed by randomization to either continue smoking cigarettes, switch to using mentholated or non-mentholated variants of glo™, switch to using a non-mentholated variant of iQOS, or quit nicotine and tobacco product use completely for 5 days. Baseline and post-randomization 24-h urine samples were collected for BoE analysis. Carbon monoxide was measured daily in exhaled breath (eCO). RESULTS: On day 5 after switching, urinary BoE (excluding for nicotine) and eCO levels were significantly (p < .05) reduced by medians between 20.9% and 92.1% compared with baseline in all groups either using glo™ or iQOS or quitting tobacco use. Between-group comparisons revealed that the reductions in the glo™ groups were similar (p > .05) to quitting in many cases. CONCLUSIONS: glo™ or iQOS use for 5 days reduced exposure to smoke toxicants in a manner comparable to quitting tobacco use. THPs are reduced exposure tobacco products with the potential to be MRTPs. IMPLICATIONS: This clinical study demonstrates that when smokers switched from smoking combustible cigarettes to using tobacco heating products their exposure to smoke toxicants was significantly decreased. In many cases, this was to the same extent as that seen when they quit smoking completely. This may indicate that these products have the potential to be reduced exposure and/or reduced risk tobacco products when used by smokers whose cigarette consumption is displaced completely. CLINICAL TRIAL REGISTRATIONS: ISRCTN14301360 and UMIN000024988.

A randomised, controlled, two-Centre open-label study in healthy Japanese subjects to evaluate the effect on biomarkers of exposure of switching from a conventional cigarette to a tobacco heating product.

BACKGROUND: Smoking is a leading cause of numerous human disorders including lung cancer, chronic obstructive pulmonary disease, and atherosclerotic cardiovascular disease. The development of modified risk tobacco products (MRTPs) has been suggested as a possible way to reduce the risks of tobacco smoking by reducing exposure to cigarette smoke toxicants. This study is designed to investigate whether biomarkers of such exposure are reduced when smokers switch from smoking commercial cigarettes to using either a novel or a commercially-available tobacco heating product (THP). DESIGN AND METHODS: This study will assess biomarkers of exposure in current smokers who either remain smoking, switch to THP use, or quit all tobacco use completely, for 5 days. The study is an in-clinic (confinement) two-centre, randomised controlled clinical study with a forced-switching design. Subjects of either gender will be aged 23-55 years (minimum legal smoking age plus 3 years), of Japanese origin and with a verified smoking status (assessed by exhaled breath carbon monoxide and urinary cotinine levels). Subjects will have a usual brand cigarette within the International Organisation for Standardisation (ISO) tar band of 6-8 mg and will be judged to be healthy by medical history, physical examination, vital signs, electrocardiography (ECG), clinical biochemistry and lung function tests. The primary objective of this study is to assess changes within groups in selected biomarkers of exposure (BoE) and of biological effect (BoBE) after a forced switch from a commercial control cigarette to either a menthol or a non-menthol THP. Secondary objectives are to assess between-group differences, to determine nicotine pharmacokinetics for cigarettes and THPs, to assess subject's satisfaction with the study products, and to monitor additional endpoints related to safety and product use. DISCUSSION: Data from this study will advance our scientific understanding of the changes in exposure to cigarette smoke toxicants in smokers who switch to using a THP. TRIAL REGISTRATIONS: UMIN000024988 (25th November 2016); ISRCTN14301360 (14th December 2016).

A system dynamics modelling approach to assess the impact of launching a new nicotine product on population health outcomes.

In 2012 the US FDA suggested the use of mathematical models to assess the impact of releasing new nicotine or tobacco products on population health outcomes. A model based on system dynamics methodology was developed to project the potential effects of a new nicotine product at a population level. A model representing traditional smoking populations (never, current and former smokers) and calibrated using historical data was extended to a two-product model by including electronic cigarettes use statuses. Smoking mechanisms, such as product initiation, switching, transition to dual use, and cessation, were represented as flows between smoking statuses (stocks) and the potential effect of smoking renormalisation through a feedback system. Mortality over a 50-year period (2000-2050) was the health outcome of interest, and was compared between two scenarios, with and without e-cigarettes being introduced. The results suggest that by 2050, smoking prevalence in adults was 12.4% in the core model and 9.7% (including dual users) in the counterfactual. Smoking-related mortality was 8.4% and 8.1%, respectively. The results suggested an overall beneficial effect from launching e-cigarettes and that system dynamics could be a useful approach to assess the potential population health effects of nicotine products when epidemiological data are not available.

E-cigarette Nicotine Delivery: Data and Learnings from Pharmacokinetic Studies.

OBJECTIVES: E-cigarettes could potentially play a major role in tobacco harm reduction by delivering nicotine in a vapor containing significantly fewer toxicants than cigarette smoke and may aid smoking behavior changes such as reduction or cessation. METHODS: We examined blood nicotine levels in smokers who were non-accustomed to e-cigarette use (Study 1) and accustomed e-cigarette users (Study 2). We compared nicotine levels when participants used a closed modular system e-cigarette to those when participants smoked a cigarette. RESULTS: In Study 1, Cmax (geometric mean (CV)) during a 5-minute puffing period (10 puffs, 30 seconds apart) was 13.4 (51.4) ng/ ml for a regular cigarette. The e-cigarette Cmax was significantly lower (p .05) at 2.5 (67.8) ng/ml. In Study 2, during a 5-minute ad libitum puffing period, cigarette Cmax was 7.2 (130.8) ng/mL, and it was 7.8 (108.2) ng/mL for the e-cigarette. CONCLUSIONS: Our data demonstrate heterogeneity of nicotine deliveries both between products and also with the same products used by different cohorts, eg, accustomed users versus smokers. Such differences must be taken into account when determining the likely behavioral impact, on smoking reduction and cessation, of nicotine delivery data and when planning e-cigarette nicotine pharmacokinetic studies.

Electronic cigarette aerosol induces significantly less cytotoxicity than tobacco smoke.

Electronic cigarettes (E-cigarettes) are a potential means of addressing the harm to public health caused by tobacco smoking by offering smokers a less harmful means of receiving nicotine. As e-cigarettes are a relatively new phenomenon, there are limited scientific data on the longer-term health effects of their use. This study describes a robust in vitro method for assessing the cytotoxic response of e-cigarette aerosols that can be effectively compared with conventional cigarette smoke. This was measured using the regulatory accepted Neutral Red Uptake assay modified for air-liquid interface (ALI) exposures. An exposure system, comprising a smoking machine, traditionally used for in vitro tobacco smoke exposure assessments, was adapted for use with e-cigarettes to expose human lung epithelial cells at the ALI. Dosimetric analysis methods using real-time quartz crystal microbalances for mass, and post-exposure chemical analysis for nicotine, were employed to detect/distinguish aerosol dilutions from a reference Kentucky 3R4F cigarette and two commercially available e-cigarettes (Vype eStick and ePen). ePen aerosol induced 97%, 94% and 70% less cytotoxicity than 3R4F cigarette smoke based on matched EC50 values at different dilutions (1:5 vs. 1:153 vol:vol), mass (52.1 vs. 3.1 µg/cm2) and nicotine (0.89 vs. 0.27 µg/cm2), respectively. Test doses where cigarette smoke and e-cigarette aerosol cytotoxicity were observed are comparable with calculated daily doses in consumers. Such experiments could form the basis of a larger package of work including chemical analyses, in vitro toxicology tests and clinical studies, to help assess the safety of current and next generation nicotine and tobacco products.

Cigarette smoke induced genotoxicity and respiratory tract pathology: evidence to support reduced exposure time and animal numbers in tobacco product testing.

Many laboratories are working to develop in vitro models that will replace in vivo tests, but occasionally there remains a regulatory expectation of some in vivo testing. Historically, cigarettes have been tested in vivo for 90 days. Recently, methods to reduce and refine animal use have been explored. This study investigated the potential of reducing animal cigarette smoke (CS) exposure to 3 or 6 weeks, and the feasibility of separate lung lobes for histopathology or the Comet assay. Rats were exposed to sham air or CS (1 or 2 h) for 3 or 6 weeks. Respiratory tissues were processed for histopathological evaluation, and Alveolar type II cells (AEC II) isolated for the Comet assay. Blood was collected for Pig-a and micronucleus quantification. Histopathological analyses demonstrated exposure effects, which were generally dependent on CS dose (1 or 2 h, 5 days/week). Comet analysis identified that DNA damage increased in AEC II following 3 or 6 weeks CS exposure, and the level at 6 weeks was higher than 3 weeks. Pig-a mutation or micronucleus levels were not increased. In conclusion, this study showed that 3 weeks of CS exposure was sufficient to observe respiratory tract pathology and DNA damage in isolated AEC II. Differences between the 3 and 6 week data imply that DNA damage in the lung is cumulative. Reducing exposure time, plus analyzing separate lung lobes for DNA damage or histopathology, supports a strategy to reduce and refine animal use in tobacco product testing and is aligned to the 3Rs (replacement, reduction and refinement).

Reference change values in concentrations of urinary and salivary biomarkers of exposure and mouth level exposure in individuals participating in an ambulatory smoking study.

BACKGROUND: Modified-risk tobacco products (MRTPs) are being developed that may contribute to tobacco harm reduction. To support reduced exposure or risk claims, a scientific framework needs to be developed to assess the validity of claims and monitor consumers after product launch. We calculated reference change values (RCVs) for biomarker of exposure (BoE): salivary cotinine and hydroxycotinine; and urinary total nicotine equivalents, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and creatinine. Mouth-level exposure (MLE) to nicotine and tar were also recorded in an ambulatory setting to characterise variation among smokers in their everyday environment. METHODS: This non-residential, observational study was conducted over 3.5 years across 10 sites in Germany. Smokers of the same commercial 10 mg ISO tar product were included in the study (N=1011). Urine samples, questionnaires and cigarette filters were collected every 6 months for a total of seven timepoints. RESULTS: Greater variability in BoEs was observed compared with confined clinical studies. Gaussian distributed data showed 2-sided values over 100%, which are uninformative for decreases. The proportion of significant changes increased slightly among switchers, probably as a result of additional variability due to the range of products used post-switching. Overall proportions of changes remained small, consistent with literature reporting that when switching to a different tar yield cigarette, smokers partially compensate by changing their smoking behaviour. CONCLUSION: Variability estimates and RCVs can be useful for monitoring subjects' BoE and MLE endpoints in longitudinal smoking studies where subjects are followed in their own environment and to aid sample size calculation of studies involving these endpoints.