Cigarette Smoke Constituents Research Articles

Investigation of Tobacco Pyrolysis Gases and Puff-by-puff Resolved Cigarette Smoke by Single Photon Ionisation (SPI) - Time-of-flight Mass Spectrometry (TOFMS)

Abstract The work presented deals with the application of Single Photon Ionisation- Time-of-Flight Mass Spectrometry (SPI-TOFMS) for the investigation of tobacco smoke. SPI-TOFMS is a modern analytical technique, which enables the simultaneous analysis of a large number of organic species in complex gas mixtures in real time. The paper is a summary of a PhD thesis (1) and seven research articles, which were recently published in various scientific journals (2-8). Consequently, more detailed information on particular aspects can be found in there. The experimental part covers two different approaches, and therefore, it is divided into two sub-sections. In the first one, the SPI-TOFMS is coupled to a pyrolysis furnace. The objective is to examine the thermal behaviour of tobacco under various controlled conditions. In so doing, three tobacco types (Virginia, Oriental, and Burley) were pyrolysed in two reaction gas compositions (nitrogen and synthetic air) and seven different furnace temperatures (400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, and 1000 °C). Results can help to unravel the complex formation and decomposition reactions taking place when tobacco is heated. In the second part the SPI-TOFMS is connected to a cigarette smoking machine in order to investigate the behaviour of cigarette smoke constituents on a puff-by-puff basis. The work incorporates the comparison of whole smoke and gas phase of cigarette smoke, a puff-resolved quantification of several hazardous smoke constituents, and the overall chemical characterisation of the individual smoking puffs. In addition, a critical consideration of the prevailing smoking procedure is given when applied to single puff analysis. A further study examines the influence of five different cigarette lighting devices (gas lighter, electric lighter, candle, match, and burning zone of another cigarette) on the chemical composition of the first puff.

Glutathione-S-transferase P protects against endothelial dysfunction induced by exposure to tobacco smoke

Exposure to tobacco smoke impairs endothelium-dependent arterial dilation. Reactive constituents of cigarette smoke are metabolized and detoxified by glutathione-S-transferases (GSTs). Although polymorphisms in GST genes are associated with the risk of cancer in smokers, the role of these enzymes in regulating the cardiovascular effects of smoking has not been studied. The P isoform of GST (GSTP), which catalyzes the conjugation of electrophilic molecules in cigarette smoke such as acrolein, was expressed in high abundance in the mouse lung and aorta. Exposure to tobacco smoke for 3 days (5 h/day) decreased total plasma protein. These changes were exaggerated in GSTP(-/-) mice. Aortic rings isolated from tobacco smoke-exposed GSTP(-/-) mice showed greater attenuation of ACh-evoked relaxation than those from GSTP(+/+) mice. The lung, plasma, and aorta of mice exposed to tobacco smoke or acrolein (for 5 h) accumulated more acrolein-adducted proteins than those tissues of mice exposed to air, indicating that exposure to tobacco smoke results in the systemic delivery of acrolein. Relative to GSTP(+/+) mice, modification of some proteins by acrolein was increased in the aorta of GSTP(-/-) mice. Aortic rings prepared from GSTP(-/-) mice that inhaled acrolein (1 ppm, 5 h/day for 3 days) or those exposed to acrolein in an organ bath showed diminished ACh-induced arterial relaxation more strongly than GSTP(+/+) mice. Acrolein-induced endothelial dysfunction was prevented by pretreatment of the aorta with N-acetylcysteine. These results indicate that GSTP protects against the endothelial dysfunction induced by tobacco smoke exposure and that this protection may be related to the detoxification of acrolein or other related cigarette smoke constituents.

Cigarette smoke causes follicle loss in mice ovaries at concentrations representative of human exposure

Cigarette smoke is a documented reproductive toxicant associated with infertility and ovarian failure. However, the underlying mechanism(s) regulating the toxic effects of cigarette smoke are unknown. Therefore, we tested the hypothesis that mainstream cigarette smoke and a cigarette smoke constituent, benzo[a]pyrene (BaP), induce apoptosis in ovarian follicles. Mice were exposed to mainstream cigarette smoke and the ovaries were analysed for follicle loss and markers of apoptosis (TUNEL, Caspase 3, Caspase 8, Bax, Bcl-2, Fas and FasL). Isolated ovaries from female pups were cultured in media containing increasing concentrations of BaP (1-10 000 ng ml(-1)), and markers of apoptosis were quantified. Cigarette smoke exposure induced a significant reduction in the number of primordial follicles, but not growing or antral follicles compared with controls. Mainstream cigarette smoke exposure had no effect on any marker of apoptosis measured. Exposure of ovaries to BaP in vitro resulted in an increase in the pro-survival marker Bcl-2, but no change in apoptosis. Our data suggest that cigarette smoke-induced follicle loss is not mediated via BaP-induced apoptosis.

Comparison of Environmental Tobacco Smoke (ETS) Concentrations Generated by an Electrically Heated Cigarette Smoking System and a Conventional Cigarette

Smoking conventional lit-end cigarettes results in exposure of nonsmokers to potentially harmful cigarette smoke constituents present in environmental tobacco smoke (ETS) generated by sidestream smoke emissions and exhaled mainstream smoke. ETS constituent concentrations generated by a conventional lit-end cigarette and a newly developed electrically heated cigarette smoking system (EHCSS) that produces only mainstream smoke and no sidestream smoke emissions were investigated in simulated “office” and “hospitality” environments with different levels of baseline indoor air quality. Smoking the EHCSS (International Organisation for Standardization yields: 5 mg tar, 0.3 mg nicotine, and 0.6 mg carbon monoxide) in simulated indoor environments resulted in significant reductions in ETS constituent concentrations compared to when smoking a representative lit-end cigarette (Marlboro: 6 mg tar, 0.5 mg nicotine, and 7 mg carbon monoxide). In direct comparisons, 24 of 29 measured smoke constituents (83%) showed mean reductions of greater than 90%, and 5 smoke constituents (17%) showed mean reductions between 80% and 90%. Gas–vapor phase ETS markers (nicotine and 3-ethenylpyridine) were reduced by an average of 97% (range 94–99%). Total respirable suspended particles, determined by online particle measurements and as gravimetric respirable suspended particles, were reduced by 90% (range 82–100%). The mean and standard deviation of the reduction of all constituents was 94 ± 4%, indicating that smoking the new EHCSS in simulated “office” and “hospitality” indoor environments resulted in substantial reductions of ETS constituents in indoor air.

Oxidative stress and accelerated vascular aging: implications for cigarette smoking

Cigarette smoking is the major cause of preventable morbidity and mortality in the United States and constitutes a major risk factor for atherosclerotic vascular disease, including coronary artery disease and stroke. Increasing evidence supports the hypothesis that oxidative stress and inflammation provide the pathophysiological link between cigarette smoking and CAD. Previous studies have shown that cigarette smoke activates leukocytes to release reactive oxygen and nitrogen species (ROS/RNS) and secrete pro-inflammatory cytokines, increases the adherence of monocytes to the endothelium and elicits airway inflammation. Here we present an overview of the direct effects of water-soluble cigarette smoke constituents on endothelial function, vascular ROS production and inflammatory gene expression. The potential pathogenetic role of peroxynitrite formation, and downstream mechanisms including poly(ADP-ribose) polymerase (PARP) activation in cardiovascular complications in smokers are also discussed.

Amelioration of pulmonary dysfunction and neutrophilic inflammation by PPARγ agonist in LPS-exposed guinea pigs

Airway dysfunction and pulmonary neutrophilic inflammation are the major characteristics of inflammatory conditions of lungs like chronic obstructive pulmonary disease (COPD). Lipopolysaccharide (LPS), a constituent of cigarette smoke, has been identified as the most important risk factor for COPD development. Inhalation exposure to LPS or cigarette smoke elicits an inflammatory response accompanied by airway hyperresponsiveness, elevated proinflammatory mediators and inflammatory cells similar to COPD. In the present study, we have evaluated the effects of pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, in LPS-induced pulmonary dysfunction, inflammatory changes and oxidative stress in guinea pigs. Inhalation exposure to nebulised LPS (30 μg ml −1) resulted in significant increase in the breathing frequency and bronchoconstriction accompanied with a significant decrease in tidal volume. Our results demonstrated that the LPS-induced pulmonary dysfunction was temporally associated with neutrophil infiltration as evident from heavy neutrophilia, increased TNFα in bronchoalveolar lavage fluid (BAL), elevated myeloperoxidase (MPO) level and histology of the lung tissue. Exposure to LPS also produced significant increase in tissue malondialdehyde (MDA) level indicating underlying oxidative stress. The results also reveal that pioglitazone (3, 10 and 30 mg kg −1, p.o.) is effective in abrogating the pulmonary dysfunction by attenuating neutrophilia, TNFα release and oxidative stress in LPS-induced model of acute lung inflammation. Results from the present study have added to the emergent body of evidence that PPARγ agonists are effective in the therapy of inflammatory disease of the lungs.

Measurement of oxidative DNA damage induced by mainstream cigarette smoke in cultured NCI-H292 human pulmonary carcinoma cells

Cigarette smoke is a complex dynamic mixture of more than 4800 chemicals distributed between the particulate and vapour phases. It is widely acknowledged that cigarette smoke is capable of causing oxidative damage in DNA, either directly or through generation of reactive oxygen species. In this study, we have used a novel system for exposing cultured NCI-H292 human pulmonary carcinoma cells at the air–liquid interface, to investigate the potential effects of cigarette smoke on oxidative DNA damage by use of the modified comet assay with formamidopyrimidine N-glycosylase (FPG) and endonuclease III (Endo III) to reveal purine and pyrimidine lesions, respectively. The results demonstrate that NCI-H292 cells exposed to mainstream cigarette smoke from Kentucky reference-cigarettes show considerable DNA damage in terms of strand-breaks (SBs), alkali-labile sites (ALS) and oxidative DNA lesions. Initial measurements of FPG-sensitive oxidative lesions were confounded by high levels of SBs and ALS. Strand-breaks, but not oxidative lesions are repaired during a 20-h recovery period, which allows the semi-quantitative measurement of FPG-sensitive oxidative DNA lesions. We also conclude that mainstream cigarette smoke does not generate increased levels of Endo III-sensitive oxidative DNA lesions, or that they are not distinguishable from SBs and ALS in vitro in this system. Moreover, we demonstrate the viability and versatility of this exposure system in combination with in vitro techniques as an investigative tool for damage induced by cigarette smoke and smoke constituents.

Evaluation of biomarkers of exposure to selected cigarette smoke constituents in adult smokers switched to carbon-filtered cigarettes in short-term and long-term clinical studies

Cigarette smoke is a complex aerosol that includes a gas vapor phase and a particulate phase. Inclusion of activated carbon in the cigarette filter can reduce some of the gas-phase smoke constituents implicated as toxicologically relevant. The present study evaluated exposure to selected gas-phase constituents when adult smokers switched to prototype cigarettes with a highly activated carbon filter. Smokers (N = 160) in two separate studies were randomized to continue to smoke conventional cigarettes (either a 6-mg or 11-mg FTC tar product), to smoke test cigarettes containing carbon filters (comparable tar levels), or to stop smoking. After completing 8 days in controlled smoking conditions (short-term studies), smokers had the option to continue in 24-week long-term ambulatory studies with unrestricted smoking. Urinary excretion of mercapturic acid metabolites of 1,3-butadiene, acrolein, and benzene; nicotine and five of its metabolites, total NNAL, and 1-hydroxypyrene were measured at baseline in the conventional cigarette group, in all groups in the short-term studies, and every 4 weeks in the long-term studies. In the short-term studies, statistically significant reductions (>70%, p<.001) in gas-phase biomarker levels were observed in the test cigarette group for both tar level products compared with the conventional cigarette group. These reductions were similar to those observed in the stop-smoking groups. The reductions continued consistently (p<.001) throughout the long-term studies. Switching to test cigarettes minimally affected the particulate-phase biomarkers. Statistically significant and consistent reductions in selected gas vapor phase biomarkers were observed when smokers switched to activated carbon filter cigarettes.

Mutagenicity, stable DNA adducts, and abasic sites induced in Salmonella by phenanthro[3,4- b]- and phenanthro[4,3- b]thiophenes, sulfur analogs of benzo[ c]phenanthrene

Sulfur-containing polycyclic aromatic hydrocarbons (thia-PAHs or thiaarenes) are common constituents of air pollution and cigarette smoke, but only a few have been studied for health effects. We evaluated the mutagenicity in Salmonella TA98, TA100, and TA104 of two sulfur-containing derivatives of benzo[ c]phenanthrene, phenanthro[3,4- b]thiophene (P[3,4- b]T), and phenanthro[4,3- b]thiophene (P[4,3- b]T) as well as their dihydrodiol and sulfone derivatives. In addition, we assessed levels of stable DNA adducts (by 32P-postlabeling) as well as abasic sites (by an aldehydic-site assay) produced by six of these compounds in TA100. P[3,4- b]T and its 6,7- and 8,9-diols, P[3,4- b]T sulfone, P[4,3- b]T, and its 8,9-diol were mutagenic in TA100. P[3,4- b]T sulfone, the most potent mutagen, was approximately twice as potent as benzo[ a]pyrene in both TA98 and TA100. Benzo-ring dihydrodiols were much more potent than K-region dihydrodiols, which had little or no mutagenic activity in any strain. P[3,4- b]T sulfone produced abasic sites and not stable DNA adducts; the other five compounds examined, B[ c]P, B[ c]P 3,4-diol, P[3,4- b]T, P[3,4- b]T 8,9-diol, and P[4,3- b]T 8,9-diol, produced only stable DNA adducts. P[3,4- b]T sulfone was the only compound that produced significant levels of frameshift mutagenicity and induced mutations primarily at GC sites. In contrast, B[ c]P, its 3,4-diol, and the 8,9 diols of the phenanthrothiophenes induced mutations primarily at AT sites. P[3,4 -b]T was not mutagenic in TA104, whereas P[3,4- b]T sulfone was. The two isomeric forms (P[3,4- b]T and P[4,3- b]T) are apparently activated differently, with the latter, but not the former, involving a diol pathway. This study is the first illustrating the potential importance of abasic sites in the mutagenicity of thia-PAHs.

How do we solve the puzzle of unintended consequences of inflammation? Systematically

the odds are high that the inflammatory process will play a key role not only in protecting us from harm over the course of our lives, but also in triggering our deaths. The benefits of the inflammatory process lie in its ability to respond to a variety of stresses and to promote adaptation. The

Fetal growth restriction triggered by polycyclic aromatic hydrocarbons is associated with altered placental vasculature and AhR-dependent changes in cell death

Maternal cigarette smoking is considered an important risk factor associated with fetal intrauterine growth restriction (IUGR). Polycyclic aromatic hydrocarbons (PAHs) are well-known constituents of cigarette smoke, and the effects of acute exposure to these chemicals at different gestational stages have been well established in a variety of laboratory animals. In addition, many PAHs are known ligands of the aryl hydrocarbon receptor (AhR), a cellular xenobiotic sensor responsible for activating the metabolic machinery. In this study, we have applied a chronic, low-dose regimen of PAH exposure to C57Bl/6 female mice before conception. This treatment caused IUGR in day 15.5 post coitum (d15.5) fetuses and yielded abnormalities in the placental vasculature, resulting in significantly reduced arterial surface area and volume of the fetal arterial vasculature of the placenta. However, examination of the small vasculature within the placental labyrinth of PAH-exposed dams revealed extensive branching and enlargement of these vessels, indicating a possible compensatory mechanism. These alterations in vascularization were accompanied by reduced placental cell death rates, increased expression levels of antiapoptotic Xiap, and decreased expression of proapoptotic Bax, cleaved poly(ADP-ribose) polymerase-1, and active caspase-3. AhR-deficient fetuses were rescued from PAH-induced growth restriction and exhibited no changes in the labyrinthine cell death rate. The results of this investigation suggest that chronic exposure to PAHs is a contributing factor to the development of IUGR in human smokers and that the AhR pathway is involved.

Nicotine and oxidative cigarette smoke constituents induce immune-modulatory and pro-inflammatory dendritic cell responses

Chronic airway inflammation is a cardinal feature of chronic obstructive pulmonary disease (COPD), a destructive cigarette smoke-induced lung disease. Although it is apparent that dendritic cells (DCs) are an important constituent of the chronic inflammatory cell influx found in airways of COPD patients, the functional roles of DCs in the pathogenesis of smoking-induced emphysema are unknown. We postulated that DCs activated by cigarette smoke constituents directly participate in the chronic inflammation that characterizes COPD airways. Concordant with this hypothesis, we observed that incubation of DCs with cigarette smoke extract (CSE), and chronic exposure of mice to cigarette smoke, both augmented the generation of neutrophilic chemokines by immature and lipopolysaccharide (LPS) or CD40L-matured DCs. The generation of interleukin-8 (CXCL8/IL-8) by human DCs conditioned with CSE was suppressed by the anti-oxidant n-acetyl cysteine (NAC), implying the involvement of oxidant sensitive pathways as a primary mechanism involved in the enhanced CXCL8/IL-8 generation. Cigarette smoke extract and nicotine also augment the production of secreted prostaglandin-E 2 and intra-cellular cyclo-oxygenase-2 (COX-2) in maturing DCs. Whereas NAC suppressed production of CXCL8 by CSE-conditioned DCs, it augmented production of PGE 2 and cellular COX-2 levels in maturing DCs. These studies indicate that the stimulation of DCs by cigarette smoke-induced oxidative stress and nicotine promote the generation of pro-inflammatory responses that promote chronic inflammation in smokers. Certain pharmacologic strategies such as anti-oxidant therapy may be only partially effective in mitigating cigarette smoke-induced pro-inflammatory DC-mediated responses in smokers.

A randomized, controlled exposure study in adult smokers of full flavor Marlboro cigarettes switching to Marlboro Lights or Marlboro Ultra Lights cigarettes

Rationale. To date no state-of-the-art clinical study has been conducted to address the question as to whether switching to lower tar cigarettes reduces exposure to smoke constituents in humans. Methods. Randomized, controlled, forced switching study in 225 adult smokers of full flavor Marlboro (MFF) cigarettes for 8 days with a 24-week follow-up. Subjects smoked MFF (a 15-mg Federal Trade Commission (FTC) tar cigarette) at baseline and were randomized to smoke 11-mg Marlboro Lights (ML) or 6-mg Marlboro Ultra Lights (MUL) cigarettes. Biomarkers of exposure to nicotine, 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), pyrene, CO, benzene, acrolein, and mutagenic substances were measured. Results. In the short-term phase, switching from MFF to ML showed statistically significant decreases in nicotine exposure (−13%) and non-significant increases in CO exposure (+6%), while switching from MFF to MUL showed statistically significant decreases in nicotine (−27%) and CO (−13%) exposure. Both nicotine and CO biomarkers trended similarly in the 24-week follow-up as in the short-term phase. The other biomarkers of cigarette smoke constituents followed the same trend as nicotine at the end of the 24-week follow-up. Conclusions. Switching smokers to lower FTC tar yield cigarettes, on average, reduces nicotine and other biomarkers considered surrogates of tar exposure.

BPDE Induced Lymphocytic Chromosome 3p Deletions May Predict Renal Cell Carcinoma Risk

Cigarette smoking is a risk factor for renal cell carcinoma. BPDE (benzo[alpha]pyrene diol epoxide) (Midwest Research Institute, Kansas City, Missouri), which is a major constituent of cigarette smoke, induces 3p aberrations that are associated with susceptibility to other smoking associated cancers. Because chromosome 3p deletions are known to be the most frequent genetic alterations in renal cell carcinoma, we tested whether 3p sensitivity to BPDE predicts susceptibility to renal cell carcinoma. Cultured peripheral blood lymphocytic cells from 170 cases and 135 controls were treated with 2 microM BPDE for 24 hours and assessed for 3p deletions by fluorescence in situ hybridization using probes directed to 3p25.2, 3p21.3, 3p14.2 and 3p12.2. A probe for 3q13 served as a control. One thousand lymphocyte interphases were scored per sample. At each locus BPDE induced 3p deletions were significantly more common in cases than in controls. No significant differences between cases and controls were observed for deletions in 3q13. Using the median value in controls as the cutoff point for BPDE sensitivity we found that the OR in subjects with high BPDE sensitivity at 3p25.2, 3p21.3, 3p14.2 and 3p12.2 was 2.02 (95% CI 1.18-3.46), 2.28 (95% CI 1.33-3.92), 1.84 (95% CI 1.07-3.16) and 1.97 (95% CI 1.15-3.37), respectively. There were dose dependent relationships between the number of deletions at each locus and the risk of renal cell carcinoma. This study demonstrates that chromosome 3p may be a specific molecular target of cigarette carcinogens and BPDE sensitivity in chromosome 3p may reflect the genetic susceptibility of an individual to renal cell carcinoma.

Cigarette smoke chemistry market maps under Massachusetts Department of Public Health smoking conditions

This study extends the market mapping concept introduced by Counts et al. (Counts, M.E., Hsu, F.S., Tewes, F.J., 2006. Development of a commercial cigarette “market map” comparison methodology for evaluating new or non-conventional cigarettes. Regul. Toxicol. Pharmacol. 46, 225–242) to include both temporal cigarette and testing variation and also machine smoking with more intense puffing parameters, as defined by the Massachusetts Department of Public Health (MDPH). The study was conducted over a two year period and involved a total of 23 different commercial cigarette brands from the U.S. marketplace. Market mapping prediction intervals were developed for 40 mainstream cigarette smoke constituents and the potential utility of the market map as a comparison tool for new brands was demonstrated. The over-time character of the data allowed for the variance structure of the smoke constituents to be more completely characterized than is possible with one-time sample data. The variance was partitioned among brand-to-brand differences, temporal differences, and the remaining residual variation using a mixed random and fixed effects model. It was shown that a conventional weighted least squares model typically gave similar prediction intervals to those of the more complicated mixed model. For most constituents there was less difference in the prediction intervals calculated from over-time samples and those calculated from one-time samples than had been anticipated. One-time sample maps may be adequate for many purposes if the user is aware of their limitations. Cigarette tobacco fillers were analyzed for nitrate, nicotine, tobacco-specific nitrosamines, ammonia, chlorogenic acid, and reducing sugars. The filler information was used to improve predicting relationships for several of the smoke constituents, and it was concluded that the effects of filler chemistry on smoke chemistry were partial explanations of the observed brand-to-brand variation.

Differential effects of cigarette smoke constituents on pro‐inflammatory dendritic cell functions

Dendritic cells (DC) are key regulators of immunity. Chronic obstructive pulmonary disease [COPD], a destructive lung disease that affects smokers, is associated with chronic airway inflammation. Although increased DC numbers are found in COPD airways, their functional roles in the pathogenesis of COPD are not well‐defined. We postulated that DCs activated by cigarette smoke constituents directly promote chronic airway inflammation. Concordant with this hypothesis, we observed that incubation of DCs with cigarette smoke extract [CSE], and chronic exposure of mice to cigarette smoke, both augmented the generation of neutrophilic chemokines by immature and lipopolysaccharide [LPS] or CD40L‐matured DCs. The generation of IL‐8 by human DCs conditioned with CSE was completely suppressed by the anti‐oxidant n‐acetyl cysteine [NAC]. Cigarette smoke extract and nicotine augmented the production of secreted prostaglandin‐E2 and intracellular cyclo‐oxygenase‐2 in maturing DCs. Whereas the production of IL‐8 by CSE‐conditioned DCs was suppressed by anti‐oxidants, PGE2 production was augmented by anti‐oxidants, and suppressed by inhibitors of nicotinic signaling. These studies indicate that certain pharmacologic strategies such as anti‐oxidant therapy may be only partially effective in mitigating pro‐inflammatory DC‐mediated responses in smokers. Supported by FARMRI research grant to RV.

Effects of methylated chrysenes on AhR-dependent and -independent toxic events in rat liver epithelial cells

Methylated chrysenes (MeChry) are important cigarette smoke constituents and 5-MeChry has been listed as possibly carcinogenic to humans. Although a major attention has been in past paid especially to mutagenic, tumor-initiating effects of MeChry, little is known about toxic effects of MeChry related to tumor promotion. As the position of methyl group has been repeatedly observed to determine genotoxic effects of MeChry, we examined both genotoxic and nongenotoxic effects of MeChry, using rat liver cell lines as experimental models. All six MeChry were relatively efficient aryl hydrocarbon receptor (AhR) agonists, with 3- and 6-MeChry being the most potent inducers of the AhR-mediated reporter gene activity. All six compounds disrupted contact inhibition in rat liver epithelial WB-F344 cells, a process previously reported to be AhR-dependent, suggesting that MeChry may interfere with cell cycle control in an AhR-dependent manner. In contrast, only 5- and 6-MeChry were found to acutely inhibit gap junctional intercellular communication (GJIC), another parameter correlating with tumor promoting effects of xenobiotics. Both 5- and 6-MeChry were efficient inducers of mRNA expression of enzymes involved in metabolic activation of polycyclic aromatic hydrocarbons, including cytochromes P450 1A1/1B1 and aldo-keto reductase 1C9. However, only 5-MeChry, and not 6-MeChry, induced significant formation of DNA adducts in rat liver epithelial cells, which corresponded with its ability to induce high accumulation of cells in S-phase. On the other hand, 5-MeChry induced neither apoptosis related to DNA damage nor phosphorylation of p53 tumor suppressor. Taken together, our results suggest that methyl group position may affect both genotoxic and nongenotoxic effects of MeChry, such as formation of DNA adducts and inhibition of GJIC. All MeChry showed a potency to disrupt cell proliferation control, while 5-MeChry was a single compound inducing DNA damage, disruption of cell cycle control and inhibition of GJIC in rat liver cells.

Cigarette smoke-induced pancreatic damage—experimental data

Epidemiological data clearly indicate that cigarette smoking is associated with an increased risk for developing chronic pancreatitis and pancreatic cancer. Despite of this clear epidemiological correlation, cigarette smoke-induced pancreatic damage has only been investigated in a small number of experimental studies. Experimental studies examining the effect of cigarette smoke or cigarette smoke constituents on the pancreas were reviewed. Recent data indicate that smoking also induces chronic pancreatic inflammation in rodents within a period of 12 weeks upon exposure with environmental cigarette smoke. Supported by the finding that morphologic pancreatic damage is also induced by nicotine treatment, cigarette smoke-induced pancreatic damage is likely to be caused by a disturbance of regulation of exocrine pancreas. The morphological alterations, however, induced by nicotine, are less pronounced and therefore, other substances and pathophysiologic mechanisms, such as carcinogen action or cigarette smoke-induced reduction of anti-protease activity, are likely to aggravate pancreatic damage upon cigarette smoke inhalation. These data indicate that several constituents of cigarette smoke induce a disturbance of pancreatic function. This multifactorial event induces morphologic pancreatic damage upon cigarette smoke exposure in rodents.

Acrolein-Activated Matrix Metalloproteinase 9 Contributes to Persistent Mucin Production

Chronic obstructive pulmonary disease (COPD), a global public health problem, is characterized by progressive difficulty in breathing, with increased mucin production, especially in the small airways. Acrolein, a constituent of cigarette smoke and an endogenous mediator of oxidative stress, increases airway mucin 5, subtypes A and C (MUC5AC) production; however, the mechanism remains unclear. In this study, increased mMUC5AC transcripts and protein were associated with increased lung matrix metalloproteinase 9 (mMMP9) transcripts, protein, and activity in acrolein-exposed mice. Increased mMUC5AC transcripts and mucin protein were diminished in gene-targeted Mmp9 mice [Mmp9((-/-))] or in mice treated with an epidermal growth factor receptor (EGFR) inhibitor, erlotinib. Acrolein also decreased mTissue inhibitor of metalloproteinase protein 3 (an MMP9 inhibitor) transcript levels. In a cell-free system, acrolein increased pro-hMMP9 cleavage and activity in concentrations (100-300 nM) found in sputum from subjects with COPD. Acrolein increased hMMP9 transcripts in human airway cells, which was inhibited by an MMP inhibitor, EGFR-neutralizing antibody, or a mitogen-activated protein kinase (MAPK) 3/2 inhibitor. Together these findings indicate that acrolein can initiate cleavage of pro-hMMP9 and EGFR/MAPK signaling that leads to additional MMP9 formation. Augmentation of hMMP9 activity, in turn, could contribute to persistent excessive mucin production.

Quantification of benzo[a]pyrene and other PAHs in the serum and follicular fluid of smokers versus non-smokers

Cigarette smoking is a well-established reproductive hazard that has been linked with decreased fertility in both smokers and those exposed to second hand smoke. The chemical components responsible for the reproductive toxic effects of cigarette smoke are unknown. Moreover, exposure of reproductive tissues to the chemical constituents of cigarette smoke is largely unknown. Therefore, we measured the levels of benzo[a]pyrene (B[a]P), and other polycyclic aromatic hydrocarbons (PAH) present in cigarette smoke, in the serum and follicular fluid of women exposed to mainstream ( n = 19) and side stream smoke ( n = 7) compared to non-smokers ( n = 10). Women exposed to mainstream smoke had significantly higher levels of B[a]P (1.32 ± 0.68 ng/ml) in their follicular fluid compared to side stream exposed (0.05 ± 0.01 ng/ml) or their non-smoking (0.03 ± 0.01 ng/ml) counterparts. More importantly we found significantly higher ( p < 0.001) levels of B[a]P in the follicular fluid of women who did not conceive (1.79 ± 0.03 ng/ml) compared to those that achieved a pregnancy (0.08 ± 0.03 ng/ml). Other PAHs known to be present in cigarette smoke were also detectable in both serum and follicular fluid of study subjects studied but with lower frequency compared to B[a]P and no differences in serum or follicular fluid levels between the groups could be demonstrated. The important finding that B[a]P reaches the follicular fluid and the fact that it is found at much higher levels in women who smoke provides further evidence that of the many toxicants present in cigarette smoke, B[a]P may be a key compound that is central to the documented adverse effects of cigarette smoke on follicular development and subsequent fertility.