Vaping has the potential to reduce the individual health risks associated with smoking and e‑cigarette flavours have been reported to help smokers’ transition from cigarettes. Here, we provide evidence to support the reduced risk potential of e-cigarette aerosols and flavours by assessing commercially available e-liquids (Vuse ePod) in a 2D in vitro screening approach. We also analysed selected flavours using a more physiologically relevant 3D (MucilAir) whole aerosol exposure model, measuring toxicity and functional endpoints such as Trans Epithelial Electrical Resistance (TEER), Cilia Beat Frequency and Active Area. To contextualise responses, we have compared e-cigarette aerosol to cigarette smoke (1R6F research cigarette) and calculated the percentage reduction using a point of departure approach. We show that aerosolised flavoured e-liquids, (appropriately stewarded) do not increase the overall measured aerosol toxicity when compared to cigarette smoke. In fact, we demonstrate that the measured in vitro cellular toxicity of flavoured e-cigarette products remains >95% reduced when compared to cigarette smoke toxicity, using point of departure (IC80) approach. Furthermore, we tested the e-liquid flavour with the highest response in the initial screening phase in a range of commercially available nicotine strengths at the time of study conduct (0 mg/ml to 34 mg/ml). The toxicity profile of this flavoured e‑liquid was not altered by increasing nicotine strength and 95% reductions from 1R6F were maintained. These data indicate that the overall product toxicity is not increased in a flavour or nicotine dependent manner and that flavoured e-cigarette products can potentially play a role in tobacco harm reduction.

AUTHORS: Emma Bishop, Nicole East, Fabio Miazzi, David Smart, Stacy Fiebelkorn, Marianna Gaca, Damien Breheny, David Thorne

AFFILIATION: B.A.T. (Investments) Limited, Southampton, UK

Background: The effect of heat-not-burn cigarette (HNBC) and electronic cigarette (Ecig) use on endothelial glycocalyx has not been investigated so far.

Material and Methods: 100 smokers were examined. 50 current smokers were randomized to HNBC use (n=25) or to Ecig puffing (n=25) and 50 smokers were used as controls and continued conventional tobacco smoking (Tcig) for 1 month. We measured perfused boundary region (PBR) of the sublingual arterial microvessels (increased PBR indicates reduced endothelial glycocalyx thickness), exhaled CO concentration and cotinine blood levels at baseline and after one month.

Results: Compared with baseline, switching to HNBC for 1-month improved only PBR5-25 (2.55±0.49 vs 2.34±0.34 μm, p=0.002). Puffing Ecig did not alter endothelial glycocalyx at any micro-vessel range throughout the study (P>0.05). Conversely, smoking Tcig for one month further deteriorated endothelial glycocalyx at all micro-vessel ranges compared with baseline (P<0.005). Cotinine blood levels were similar at baseline and after one month using HNBC (P=0.432), Ecig (P=0.535), or Tcig (P=0.489). Compared with baseline, CO concentration was decreased in HNBC and Ecig users (mean percent change: -55% and -58%, respectively P<0.001), while remained unchanged in Tcig smokers (P=0.312) at one month.

Conclusions: In this study, we observed that Tcig smokers further deteriorated endothelial glycocalyx after continuation of smoking for 1 month. Conversely, smokers switching to Ecig preserved glycocalyx integrity while those who switched to HNBC showed a modest improvement of the glycocalyx integrity in the micro-vessel ranging from 20 to 25 μm. Cotinine levels, which reflect nicotine exposure, were similar between Tcig, HNBC, and Ecig groups. Thus, impairment of endothelial glycocalyx in the Tcig group was independent from nicotine consumption and was likely related with greater exposure to toxic emissions, such as CO, after Tcig use than after switching to HNBC or Ecig.

AUTHORS: Ignatios Ikonomidis¹, Konstantinos Katogiannis¹, Kallirhoe Kourea¹, Gavriella Kostelli¹, George Pavlidis¹, John Thymis¹, Eleni Katsanaki¹, Eirini Maratou², Vaia Lambadiari²

AFFILIATIONS: ¹2^nd Cardiology Department, Attikon University Hospital, National & Kapodistrian University of Athens, Greece || ²2^nd Department of Internal Medicine, Research Unit and Diabetes Centre, Attikon University Hospital, Medical School, National and Kapodistrian University of Athens, Greece

Abrupt cessation of harmful habits and addictions is associated with numerous functional changes in several brain regions. Dopamine, serotonin, glutamate, and GABA neurotransmission may be altered in numerous neural pathways, including those related to brain reward circuitry, craving, and impulse control. Various neurobiological mechanisms of emotional regulation and stress responses may also be changed in these circumstances. In contrast, the nature of these changes may significantly differ when implementing harm reduction approaches, which involve the gradual reduction of harmful behavior or substitution with less harmful behavioral patterns. Harm reduction strategies are commonly characterized by a more controlled adjustment of neurotransmitter levels, a less pronounced imbalance of receptor expression and sensitivity, as well as fewer disruptions in intracellular signaling pathways. There are various animal experimental models that may be utilized to study harm reduction in the laboratory setting. These may include zebrafish behavioral models, self-administration and conditioned place preference models in rodents, as well as various social models in non-human primates. Limitations of these models include numerous translational issues such as the inability to adequately mimic human behavior and harmful behavioral patterns in experimental conditions. Here, we discuss current knowledge and research on the psychophysiology of harm reduction with a focus on future trends in this rapidly evolving scientific area.

AUTHOR: Igor Pantić

AFFILIATION: Department of Medical Physiology, Faculty of Medicine, University of Belgrade, Serbia

Despite decades of solid scientific information on the health risks of tobacco consumption, cigarette smoking remains a leading cause of morbidity and mortality worldwide. In recent years, modified risk products (MRPs) have revolutionized the tobacco industry gaining more and more users. The comparison between MRPs and conventional, combustion cigarettes is crucial to evaluate the potential health consequences associated with tobacco use.

In this study, which is related to CoEHAR’s Replica project (Center of Excellence for the Acceleration of Harm Reduction, University of Catania), V79 lung fibroblasts of the Chinese hamster were exposed through air-liquid interface (ALI) to conventional cigarette smoke (1R6F reference cigarette, University of Kentucky) and e-cigarette aerosol (myblu, Imperial Brands) in order to compare genotoxic effects. For the exposure of V79 cells to 1R6F cigarette undiluted smoke and myblu e-cigarette undiluted aerosol were used the Borgwaldt LM1 smoking machine and the Borgwaldt LM4E vaping machine, respectively. Initially, the cytotoxicity of V79 cells exposed to 1R6F smoke (2-30 puffs under HCI regimen) was assessed by using the neutral red uptake (NRU) assay and the EC50 was established. For the evaluation of genotoxicity to 1R6F smoke (1-4 puffs under HCI regimen) and myblu aerosol (20-100 puffs under CRM81 regimen) was performed the in vitro micronucleus (IVM) assay. In accordance with OECD Guideline 487, the IVM assay was conducted in the presence and absence of an exogenous metabolic activation system (S9 mix, 10%). It was also examined the cytotoxic effect of S9 mix by performing a dose-response curve (1-5%).

The results revealed that 1R6F smoke is highly cytotoxic (EC50=3.149 puffs) and genotoxic. In contrast, myblu aerosol showed no evidence of genotoxicity. S9 mix induced cytotoxicity in a dose-dependent manner.

In conclusion, e-cigarette aerosol resulted significantly safer compared to cigarette smoke, indicating that e-cigarettes can be beneficial in smoking harm reduction strategies.

AUTHORS: Konstantinos Partsinevelos¹, Rosalia Emma^1,2, Virginia Fuochi¹, Alfio Distefano¹, Sonja Rust³, Fahad Zadjali⁴, Mohammed Al-Tobi⁴, Antonio Giordano⁵, Ang Sun⁵, Vladislav Volarevic⁶, Konstantinos Poulas^7,8, Pio-Maria Furneri¹, Riccardo Polosa^2,9, Giovanni Li-Volti^1,2, Massimo Caruso^1,2, and the Replica Project Group*

AFFILIATIONS: ¹Department of Biomedical and Biotechnological Sciences, University of Catania, Italy || ²Center of Excellence for the Acceleration of Harm Reduction (CoEHAR), University of Catania, Italy || ³ECLAT Srl, spin-off of the University of Catania, Italy || ⁴College of Medicine and Health Sciences, Department of Clinical Biochemistry, Sultan Qaboos University, Khodh, Oman || ⁵Sbarro Institute for Cancer Research and Molecular Medicine, Department of Biology, College of Science and Technology, Temple University, Philadelphia, USA || ⁶Center for Molecular Medicine and Stem Cell Research, Department of Microbiology and Immunology, Faculty of Medical Sciences, University of Kragujevac, Serbia || ⁷Laboratory of Molecular Biology and Immunology, Department of Pharmacy, University of Patras, Greece || ⁸Institute for Research and Innovation, IRIS, Patras Science Park, Patras, Greece || ⁹Department of Clinical and Experimental Medicine, University of Catania, Italy || *Replica Project Group (Razan Zadjali⁴, Zaina Alharthi⁴, Roberta Pulvirenti¹, Aurora Costa⁵, Aleksandar Arsenijevic⁶, Konstantinos Mesiakaris^7,8)

E-cigarette regulation has two imperatives: Facilitate smoking cessation among those otherwise unwilling or unable to do so, and mitigate use by non-smokers (especially youth). Unfortunately, commonalities in the preferences of these groups means that policies designed to influence e-cigarettes’ affordability, appeal, and acceptability in pursuit of either goal risks sacrificing the other. E-cigarettes and combustibles are economic substitutes. Thus, while taxes, minimum legal sale age restrictions and flavor bans have reduced demand for e-cigarettes, they have also increased smoking and likely deter subsequent cessation. But while the substitutability of combustibles and e-cigarettes challenges regulators, it also presents an opportunity. The dual imperatives are not entirely antithetical. Sufficiently nuanced, risk-proportionate regulation could incentivize substitutions down the risk continuum, while still discouraging experimentation by non-smokers. Appropriately enforced age-gating could also improve protections against youth access, forgoing the perceived need for the ‘blunt’ demand-reduction strategies which threaten e-cigarettes’ suitability as cessation aids, and lead to a range of unintended consequences: increased smoking; deterred cessation; DIY after-market modifications; and illicit sales which sacrifice the advantages of regulatory oversight, surveillance, age-gating and tax-revenue generation. Sufficiently nuanced risk-proportionate regulations along with venue-based age-gating and focused & dynamic deterrence strategies to deter youth access would serve each of the ‘dual’ imperatives. This strategy could pay additional dividends for tobacco control: The availability of an appealing regulated and safer substitute could reduce smoker’s tendency to respond to restrictions on combustibles by embracing illicit markets. That could increase the political viability, and subsequent efficacy of taxes, menthol bans, and nicotine limits applied to combustibles. Further, commercial e-cigarettes could internalize the costs of stop smoking services, allowing funds to be reallocated to other areas, including the enforcement of age-restrictions. E-cigarette regulation is a deeply polarizing topic, but there is great potential to reconcile tobacco harm-reduction with mainstream tobacco control.

AUTHOR: Samuel Hampsher-Monk

AFFILIATION: BOTEC Analysis, Santa Clarita, California, USA

Recent technological advances have enabled the development of several novel nicotine delivery systems that deliver nicotine without combustion and help smokers move away from cigarettes. While there is a recognized need to establish regulatory standards targeting nicotine delivery to address abuse liability and toxicant exposure, the most appropriate strategy is debated. Nicotine flux was suggested as a regulatory target that considers metrics that influence nicotine emissions beyond nicotine concentration, which is the current standard in many regulatory schemes. However, both nicotine concentration and nicotine flux standards target emissions from the device rather than delivery to the users. These parameters assume a direct relationship between nicotine emission and nicotine delivery which, if incorrect, may under- or overestimate the actual nicotine delivery profile. We estimated nicotine flux from several nicotine and tobacco products including cigarettes, heated tobacco products, e-cigarettes, pouches, and several nicotine replacement therapies using definitions proposed by the Nicotine Flux Work Group to evaluate the relationship between nicotine flux and route of administration. We then evaluated the relationship between nicotine flux and nicotine delivery through various routes of administration and products using information provided from studies that provided sufficient detail to assess such a relationship. Finally, we evaluated if estimates of nicotine flux from newer tobacco products or nicotine replacement therapies predict 52-week switching or quitting success. We provide a brief perspective on the applicability of nicotine flux for human exposure and highlight the importance of considering clinical pharmacology-related paradigms when attempting to set nicotine ceilings.

AUTHOR: Carrie Wade

AFFILIATION: Philip Morris International