In vitro bioactivity of combustion products from 12 tobacco constituents

Smoking cessation: why is it a persistent problem in patients with peripheral artery disease?

Nurses play a key role in advising patients to quit smoking, especially those with long-term conditions including cardiovascular disease. Peripheral artery disease (PAD) is an increasingly prevalent condition, and is the third most common presentation of atherosclerotic disease after coronary heart disease and stroke. Smoking cessation is crucial for patients with PAD but can be very challenging. Stopping smoking reduces cardiovascular morbidity and mortality, and improves claudication symptoms in patients with PAD. Those who continue to smoke are at higher risk of disease progression, amputation, myocardial infarction and death, and have poorer therapeutic outcomes. Quitting smoking is difficult, and patients should be offered a combination of behavioural and drug therapy. Nurses can provide several interventions to help patients quit and prevent relapse. A pilot study in a large London hospital found that no smokers had been referred to smoking cessation services by their vascular clinician (although some had been referred by their GP), given brief cessation advice or told how smoking cessation was essential for vascular preservation. Many thought smoking cessation programmes would not work.

Cytotoxicity, mutagenicity and genotoxicity of electronic cigarettes emission aerosols compared to cigarette smoke: the REPLICA project

Concerns have recently increased that the integrity of some scientific research is questionable due to the inability to reproduce the claimed results of some experiments and thereby confirm that the original researcher's conclusions were justified. This phenomenon has been described as 'reproducibility crisis' and affects various fields from medicine to basic applied sciences. In this context, the REPLICA project aims to replicate previously conducted in vitro studies on the toxicity of cigarette smoke and e-cigarette aerosol, sometimes adding experiments or conditions where necessary, in order to verify the robustness and replicability of the data. In this work the REPLICA Team replicated biological and toxicological assessment published by Rudd and colleagues in 2020. As in the original paper, we performed Neutral Red Uptake (NRU) assay for the evaluation of cytotoxicity, Ames test for the evaluation of mutagenesis and In Vitro Micronuclei (IVMN) assay for the evaluation of genotoxicity on cells treated with cigarette smoke or e-cigarette aerosol. The results showed high cytotoxicity, mutagenicity and genotoxicity induced by cigarette smoke, but slight or no cytotoxic, mutagenic and genotoxic effects induced by the e-cigarette aerosol. Although the two studies presented some methodological differences, the findings supported those previously presented by Rudd and colleagues.

Diabetes- versus smoking-related thrombo-inflammation in peripheral artery disease

Peripheral artery disease (PAD) is a major health problem with increased cardiovascular mortality, morbidity and disabling critical limb threatening ischemia (CLTI) and amputation. Diabetes mellitus (DM) and cigarette smoke are the main risk factors for the development of PAD. Although diabetes related PAD shows an accelerated course with worse outcome regarding complications, mortality and amputations compared with non-diabetic patients, current medical treatment does not make this distinction and includes standard antiplatelet and lipid lowering drugs for all patients with PAD. In this review we discuss the pathophysiologic mechanisms of PAD, with focus on differences in thrombo-inflammatory processes between diabetes-related and smoking-related PAD, and hypothesize on possible mechanisms for the progressive course of PAD in DM. Furthermore, we comment on current medical treatment and speculate on alternative medical drug options for patients with PAD and DM.

Nicotine promotes atherosclerosis development in apolipoprotein E-deficient mice through α1-nAChR

α1 Nicotinic acetylcholine receptor (α1nAChR) is an important nicotine receptor that is widely distributed in vascular smooth muscle cells, macrophages, and endothelial cells. However, the role of α1nAChR in nicotine-mediated atherosclerosis remains unclear. The administration of nicotine for 12 weeks increased the area of the atherosclerotic lesion, the number of macrophages infiltrating the plaques, and the circulating levels of inflammatory cytokines, such as interleukin-6 and tumor necrosis factor-α, in apolipoprotein E-deficient (ApoE^-/- ) mice fed a high-fat diet. Nicotine also increased α1nAChR, calpain-1, matrix metalloproteinase-2 (MMP-2), and MMP-9 expression in the aortic tissue. Silencing of α1nAChR with an adenoassociated virus decreased the atherosclerotic size, lesion macrophage content, and circulating levels of inflammatory cytokines and suppressed α1nAChR, calpain-1, MMP-2, and MMP-9 expression in the nicotine group. In vitro, nicotine-induced α1nAChR, calpain-1, MMP-2, and MMP-9 expression in mouse vascular smooth muscle cells (MOVAS) and macrophages (RAW264.7), and enhanced the migration and proliferation of these cells. The silencing of α1nAChR inhibited these effects of nicotine MOVAS and RAW264.7 cells. Thus, we concluded that nicotine promoted the development of atherosclerosis partially by inducing the migration and proliferation of vascular smooth muscle cells and macrophages and inducing an inflammatory reaction. The effect of nicotine on atherogenesis may be mediated by α1nAChR-induced activation of the calpain-1/MMP-2/MMP-9 signaling pathway.

Cigarette Smoking and Adipose Tissue: The Emerging Role in Progression of Atherosclerosis

Smoking is an established risk factor for atherosclerosis through several underlying pathways. Moreover, in the development of atherosclerotic plaque formation, obesity, defined as excess fat mass accumulation, also plays a vital role in dyslipidemia and insulin resistance. Substantial evidence shows that cigarette smoking induces multiple pathological effects in adipose tissue, such as differentiation of adipocytes, lipolysis, and secretion properties in adipose tissue. Therefore, there is an emerging speculation in which adipose tissue abnormality induced by smoking or nicotine is likely to accelerate the progression of atherosclerosis. Herein, this review aims to investigate the possible interplay between smoking and adipose tissue dysfunction in the development of atherosclerosis.

New Insights Into Tobacco-Induced Vascular Disease: Clinical Ramifications

Tobacco smoke contains more than 4,000 compounds. These include phenols, carbonyls, and nitrosamines that may be irritants and carcinogens; particulate matter such as tars; volatiles and gases such as carbon monoxide; and nicotine. Many of these compounds may contribute to the adverse health effects of tobacco. For example, recent findings have shown that the angiogenic and proliferative effects of nicotine are mediated by activation of nicotinic receptors on the vascular cells. Nicotine-induced activation of vascular cells may contribute to pathological neovascularization in cancer, age-related macular degeneration, and atherosclerosis. This review focuses on how nicotine adversely affects cardiovascular health and highlights intriguing new data about nicotine's potent angiogenic and proliferative properties.

Cytotoxicity of chronic exposure to 4 cigarette smoke condensates in 2 cell lines

Tobacco use is the leading preventable cause of death. The cytotoxicity of cigarette smoke condensate (CSC), the particulate fraction of cigarette smoke without the vapor phase, has mostly been tested in short-term in vitro studies lasting from a few hours to a few days. Here, we assessed the toxicity of CSCs from 2 reference cigarettes, 3R4F and CM6, using a primary human small airway epithelial (PSAE) cell line by quantifying adenosine 5'-triphosphate (ATP), 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS), total glutathione (reduced glutathione [GSH] + oxidized glutathione [GSSG]), and lactate dehydrogenase (LDH) release over the course of 28 days. The CSCs, 0.3 to 10 μg/mL, promoted cell proliferation at 120 hours of exposure, but demonstrated cytotoxicity at days 14 and 28. Interestingly, CSCs, 0.3 to 3 μg/mL, showed a cell death effect at day 14 but induced cell proliferation at day 28. Consistently, transformation associated with morphological changes began by day 14 and the transformed cells grew dramatically at day 28. The LDH assay appeared to be sensitive for assessing early cell damage, whereas the ATP, MTS, and GSH assays were more suitable for determining later stage CSCs-induced cytotoxicity. The ATP assay showed greater sensitivity than the MTS and GSH assays. We also assessed the toxicity of CSCs in an human Telomerase Reverse Transcriptase (hTERT)-immortalized Barrett esophagus cell line (CP-C). The CP-C cells demonstrated dose- and time-dependent cytotoxicity over the course of 28 days but displayed higher resistance to CSCs than PSAE cells. This study demonstrates that CSCs cause cytotoxicity and induce transformation related to cell resistance and cell invasion properties.

IL-8 production in response to cigarette smoke is decreased in epithelial cells from COPD patients

Cigarette smoke is the principal cause of chronic obstructive pulmonary disease (COPD), a disorder characterized by airway inflammation. As epithelial cells are the first line of defense against foreign material, the response of normal epithelial cells to smoke has been extensively studied. However, little is known about how epithelial cells derived from COPD patients respond to ongoing smoke exposure. This study was aimed at comparing the intracellular response of normal human bronchial/tracheal epithelial cells (NHBE) and COPD-diseased human bronchial/tracheal epithelial cells (DHBE) to cigarette smoke. NHBE and DHBE cells were treated with cigarette smoke condensate (CSC) for 24 h. IL-8 production was measured by ELISA and western blot was used to measure TLR4 expression. Cells were pretreated with CLI-095, a TLR4 inhibitor, or the signaling pathway inhibitors PD184352, Helenalin, or PI-103, which inhibit the ERK1/2, NF-κB and PI3K pathways, respectively. NHBE cells increased IL-8 production in a dose-dependent manner in response to CSC while DHBE cells did not show any significant difference and had a much lower production of IL-8 in response to CSC compared to NHBE cells. There was no change in TLR4 expression with CSC exposure. CLI-095 and PD184352 attenuated IL-8 secretion, indicating that CSC-induced inflammation is both TLR4- and ERK1/2-dependent. These results demonstrate that NHBE and DHBE cells differentially respond to cigarette smoke. DHBE cells exhibit a dampened IL-8 release, indicating that COPD is associated with a reduced capacity of airway epithelial cells to respond to foreign material.

Particulate matter (PM) 2.5 levels in ETS emissions of a Marlboro Red cigarette in comparison to the 3R4F reference cigarette under open- and closed-door condition

INTRODUCTION

Potential health damage by environmental emission of tobacco smoke (environmental tobacco smoke, ETS) has been demonstrated convincingly in numerous studies. People, especially children, are still exposed to ETS in the small space of private cars. Although major amounts of toxic compounds from ETS are likely transported into the distal lung via particulate matter (PM), few studies have quantified the amount of PM in ETS.

STUDY AIM

The aim of this study was to determine the ETS-dependent concentration of PM from both a 3R4F reference cigarette (RC) as well as a Marlboro Red brand cigarette (MRC) in a small enclosed space under different conditions of ventilation to model car exposure.

METHOD

In order to create ETS reproducibly, an emitter (ETSE) was constructed and mounted on to an outdoor telephone booth with an inner volume of 1.75 m3. Cigarettes were smoked under open- and closed-door condition to imitate different ventilation scenarios. PM2.5 concentration was quantified by a laser aerosol spectrometer (Grimm; Model 1.109), and data were adjusted for baseline values. Simultaneously indoor and outdoor climate parameters were recorded. The time of smoking was divided into the ETS generation phase (subset "emission") and a declining phase of PM concentration (subset "elimination"); measurement was terminated after 10 min. For all three time periods the average concentration of PM2.5 (Cmean-PM2.5) and the area under the PM2.5 concentration curve (AUC-PM2.5) was calculated. The maximum concentration (Cmax-PM2.5) was taken from the total interval.

RESULTS

For both cigarette types open-door ventilation reduced the AUC-PM2.5 (RC: from 59 400 ± 14 600 to 5 550 ± 3 900 μg*sec/m3; MRC: from 86 500 ± 32 000 to 7 300 ± 2 400 μg*sec/m3; p < 0.001) and Cmean-PM2.5 (RC: from 600 ± 150 to 56 ± 40 μg/m3, MRC from 870 ± 320 to 75 ± 25 μg/m3; p < 0.001) by about 90%. Cmax-PM2.5 was reduced by about 80% (RC: from 1 050 ± 230 to 185 ± 125 μg/m3; MRC: from 1 560 ±500 μg/m3 to 250 ± 85 μg/m3; p < 0.001). In the subset "emission" we identified a 78% decrease in AUC-PM2.5 (RC: from 18 600 ± 4 600 to 4 000 ± 2 600 μg*sec/m3; MRC: from 26 600 ± 7 200 to 5 800 ± 1 700 μg*sec/m3; p < 0.001) and Cmean-PM2.5 (RC: from 430 ± 108 to 93 ± 60 μg/m3; MRC: from 620 ± 170 to 134 ± 40 μg/m3; p < 0.001). In the subset "elimination" we found a reduction of about 96-98% for AUC-PM2.5 (RC: from 40 800 ± 11 100 to 1 500 ± 1 700 μg*sec/m3; MRC: from 58 500 ± 25 200 to 1 400 ± 800 μg*sec/m3; p < 0.001) and Cmean-PM2.5 (RC: from 730 ± 200 to 27 ± 29 μg/m3; MRC: from 1 000 ± 450 to 26 ± 15 μg/m3; p < 0.001). Throughout the total interval Cmax-PM2.5 of MRC was about 50% higher (1 550 ± 500 μg/m3) compared to RC (1 050 ± 230 μg/m3; p < 0.05). For the subset "emission" - but not for the other periods - AUC-PM2.5 for MRC was 43% higher (MRC: 26 600 ± 7 200 μg*sec/m3; RC: 18 600 ± 4 600 μg*sec/m3; p < 0.05) and 44% higher for Cmean-PM2.5 (MRC: 620 ± 170 μg/m3; RC: 430 ± 108 μg/m3; p < 0.05).

CONCLUSION

This method allows reliable quantification of PM2.5-ETS exposure under various conditions, and may be useful for ETS risk assessment in realistic exposure situations. The findings demonstrate that open-door condition does not completely remove ETS from a defined indoor space of 1.75 m3. Because there is no safe level of ETS exposure ventilation is not adequate enough to prevent ETS exposure in confined spaces, e.g. private cars. Additionally, differences in the characteristics of cigarettes affect the amount of ETS particle emission and need to be clarified by ongoing investigations.

Tobacco smoke particles and indoor air quality (ToPIQ) - the protocol of a new study

Environmental tobacco smoke (ETS) is a major contributor to indoor air pollution. Since decades it is well documented that ETS can be harmful to human health and causes premature death and disease. In comparison to the huge research on toxicological substances of ETS, less attention was paid on the concentration of indoor ETS-dependent particulate matter (PM). Especially, investigation that focuses on different tobacco products and their concentration of deeply into the airways depositing PM-fractions (PM10, PM2.5 and PM1) must be stated. The tobacco smoke particles and indoor air quality study (ToPIQS) will approach this issue by device supported generation of indoor ETS and simultaneously measurements of PM concentration by laser aerosol spectrometry. Primarily, the ToPIQ study will conduct a field research with focus on PM concentration of different tobacco products and within various microenvironments. It is planned to extend the analysis to basic research on influencing factors of ETS-dependent PM concentration.

Cigarette smoke increases TLR4 and TLR9 expression and induces cytokine production from CD8(+) T cells in chronic obstructive pulmonary disease

BACKGROUND

Cigarette smoke is a major risk factor for chronic obstructive pulmonary disease (COPD), an inflammatory lung disorder. COPD is characterized by an increase in CD8(+) T cells within the central and peripheral airways. We hypothesized that the CD8(+) T cells in COPD patients have increased Toll-like receptor (TLR) expression compared to control subjects due to the exposure of cigarette smoke in the airways.

METHODS

Endobronchial biopsies and peripheral blood were obtained from COPD patients and control subjects. TLR4 and TLR9 expression was assessed by immunostaining of lung tissue and flow cytometry of the peripheral blood. CD8(+) T cells isolated from peripheral blood were treated with or without cigarette smoke condensate (CSC) as well as TLR4 and TLR9 inhibitors. PCR and western blotting were used to determine TLR4 and TLR9 expression, while cytokine secretion from these cells was detected using electrochemiluminescence technology.

RESULTS

No difference was observed in the overall expression of TLR4 and TLR9 in the lung tissue and peripheral blood of COPD patients compared to control subjects. However, COPD patients had increased TLR4 and TLR9 expression on lung CD8(+) T cells. Exposure of CD8(+) T cells to CSC resulted in an increase of TLR4 and TLR9 protein expression. CSC exposure also caused the activation of CD8(+) T cells, resulting in the production of IL-1β, IL-6, IL-10, IL-12p70, TNFα and IFNγ. Furthermore, inhibition of TLR4 or TLR9 significantly attenuated the production of TNFα and IL-10.

CONCLUSIONS

Our results demonstrate increased expression of TLR4 and TLR9 on lung CD8(+) T cells in COPD. CD8(+) T cells exposed to CSC increased TLR4 and TLR9 levels and increased cytokine production. These results provide a new perspective on the role of CD8(+) T cells in COPD.

In vitro micronucleus assay for cigarette smoke using a whole smoke exposure system: a comparison of smoking regimens

Previous studies on the biological assessment of cigarette smoke (CS) mainly focused on the total particulate matter (TPM) collected using a Cambridge filter or gas vapor phase (GVP) bubbled through phosphate-buffered saline (PBS). To study the effects of native CS in vitro, direct exposure methods have been developed. Meanwhile, in vitro micronucleus (MN) assays have been reported to evaluate the mutagenicity of CS. The objective of this research is to investigate the MN-inducing activity of whole smoke (WS) and GVP using a whole smoke exposure system, CULTEX((R)), which allows direct exposure of cultured cells to native CS at the air/liquid interface (ALI). CS was generated according to the International Organization for Standardization (ISO; 35ml, 2s, once per 60s) or the Health Canada Intensive (HCI; 55ml, 2s, once per 30s, with complete ventilation block) regimens and Chinese hamster lung (CHL/IU) cells were then exposed to this smoke. Dosages were adjusted according to the amount of smoke entering the actual exposure position. Under both smoking regimens, WS and GVP from 2R4F reference cigarettes induced MN responses. The concept of the dosage and similar dose-response relationships between theoretical and monitored dosage values under the two regimens enabled us to compare the MN-inducing activities of cigarettes in the direct exposure assay, even in the case of various experimental settings or different TPM amounts. MN-inducing activities of 2R4F under the ISO regimen seemed to be higher than those under HCI estimated by the TPM equivalent calculated values.

Sequential fractionation with concurrent chemical and toxicological characterization of the combustion products of chlorogenic acid

Chlorogenic acid is the most abundant polyphenol found in the tobacco plant. The biological effects of its combustion products remain largely unknown. In this study, chlorogenic acid was burned at 640 degrees C for 2 min and the particulate matter of the smoke was collected onto Cambridge filter pads followed by selective extraction in five different solvents. Various fractions of the chlorogenic acid combustion products were tested for induction of micronuclei in V79 Chinese hamster fibroblast cells. Over 40 compounds were identified in the dimethyl sulfoxide (DMSO) extract by high-performance liquid chromatography coupled to electrospray time-of-flight mass spectrometry (HPLC/TOF-MS). The DMSO extract was then fractionated into three major fractions by preparative LC. The fraction inducing the highest degree of toxicity was further separated into four sub-fractions. The sub-fraction responsible for the most toxic response was determined to contain catechol as its major component. The overall reproducibility of the combustion, the extraction procedure and the chemical characterization of the compounds responsible for the toxicity in the chlorogenic acid smoke were evaluated by LC/TOF-MS.

Endothelial nicotinic acetylcholine receptors and angiogenesis

Nicotinic acetylcholine receptors (nAChRs) were first described in non-excitable cells just more than a decade ago. The nAChRs on endothelial cells modulate key angiogenic processes, including endothelial cell survival, proliferation, and migration. The receptors may be stimulated by endogenous agonists such as acetylcholine, or exogenous chemicals such as nicotine, to activate physiologic angiogenesis (such as in wound healing) or pathologic angiogenesis (such as retinal neovascularization or tumor angiogenesis). The endothelial nAChRs may represent a target for therapeutic modulation of disorders characterized by insufficient or pathologic angiogenesis.