Exposure of mice to cigarette smoke and/or light causes DNA alterations in heart and aorta

The effect of smoking on atrial and ventricular functions in healthy subjects: A speckle tracking echocardiography study

PURPOSE

Smoking is a well-known risk factor for coronary artery diseases. It is also associated with nicotine-induced myocardial dysfunction. The aim of this study was to evaluate the right and left atrial and ventricular functions in apparently healthy smokers.

METHODS

We included consecutively 80 healthy smokers (56 males, mean age:35.5 ± 8.4 years) and 70 healthy nonsmokers (44 males, mean age:33.9 ± 9.5 years). None of the subjects had any additional cardiovascular risk factor other than smoking. The right and left atrial and ventricular functions were assessed by both conventional and speckle tracking echocardiography.

RESULTS

Although there was no significant difference in left ventricular ejection fraction, the smokers had significantly lower ventricular global longitudinal strain than controls (-19.9 ± 2.0% vs -21.2 ± 1.9%, P < .001 and -18.4 ± 2.1% vs -21.8 ± 2.2%, P < .001, respectively, for the left and right ventricle). Smokers had also lower atrial reservoir and conduit strains: 35.9 ± 11.1% vs 40.2 ± 11.2%, P = .022 and 16.7 ± 6.8% vs 19.4 ± 6.8%, P = .016, respectively, for the left atrium, and 33.0 ± 10.6% vs 37.6 ± 11.2%, P = .011 and 15.2 ± 5.6% vs 18.0 ± 6.3%, P = .004, respectively, for the right atrium).

CONCLUSION

Even in apparently healthy people with no other cardiovascular risk factors, smoking is associated with impaired atrial and ventricular functions.

Association between fragmented QRS complexes and left ventricular dysfunction in healthy smokers

OBJECTIVE

Smoking is a known risk factor for cardiovascular diseases and may cause myocardial damage independently of coronary artery disease. Fragmented QRS (fQRS) is an important marker of myocardial fibrosis, while speckle-tracking echocardiography is a method used to show subclinical left ventricle dysfunction.

METHODS

Our study included 230 healthy individuals aged 18-40 years. The patients included were separated into two groups: those smokers (n = 130) and non-smokers (n = 100). After that healthy smokers group were divided into two groups: those with fQRS (n = 24) and those without (n = 106). In both groups, the arithmetic mean of three images was used to obtain the left ventricle global longitudinal strain (LV-GLS). The E/SRe ratio was also calculated and analyzed.

RESULTS

There were significant differences between the smokers and non-smokers in terms of, E/SRe (55.7 ± 17.9 vs 50.3 ± 14.8; P = 0.015), LV-GLS (23.1 ± 1.9 vs 24.0 ± 1.7; P = 0.001), and fQRS (18.5% vs 6%; P = 0.005). As a result of subgroup analysis, pack-year history was higher in the fQRS positive group (16.7 ± 3.7 vs 11.2 ± 3.7, P < 0.001). While a negative correlation was observed between pack-year history and LV-GLS (r = -0.678, P < 0.001), there was a positive correlation between pack-year history and E/SRe (r = 0.730, P < 0.001).

CONCLUSION

In conclusion, our study demonstrated that fQRS is a parameter that can be used to determine left ventricle subclinical systolic and diastolic dysfunction in smokers, and that left ventricle dysfunction is related to the duration and intensity of smoking.

Immune-regulating effects of exercise on cigarette smoke-induced inflammation

Long-term cigarette smoking (LTCS) represents an important risk factor for cardiac infarction and stroke and the central risk factor for the development of a bronchial carcinoma, smoking-associated interstitial lung fibrosis, and chronic obstructive pulmonary disease. The pathophysiologic development of these diseases is suggested to be promoted by chronic and progressive inflammation. Cigarette smoking induces repetitive inflammatory insults followed by a chronic and progressive activation of the immune system. In the pulmonary system of cigarette smokers, oxidative stress, cellular damage, and a chronic activation of pattern recognition receptors are described which are followed by the translocation of the NF-kB, the release of pro-inflammatory cytokines, chemokines, matrix metalloproteases, and damage-associated molecular patterns. In parallel, smoke pollutants cross directly through the alveolus-capillary interface and spread through the systemic bloodstream targeting different organs. Consequently, LTCS induces a systemic low-grade inflammation and increased oxidative stress in the vascular system. In blood, these processes promote an increased coagulation and endothelial dysfunction. In muscle tissue, inflammatory processes activate catabolic signaling pathways followed by muscle wasting and sarcopenia. In brain, several characteristics of neuroinflammation were described. Regular exercise training has been shown to be an effective nonpharmacological treatment strategy in smoke-induced pulmonary diseases. It is well established that exercise training exerts immune-regulating effects by activating anti-inflammatory signaling pathways. In this regard, the release of myokines from contracting skeletal muscle, the elevations of cortisol and adrenalin, the reduced expression of Toll-like receptors, and the increased mobilization of immune-regulating leukocyte subtypes might be of vital importance. Exercise training also increases the local and systemic antioxidative capacity and several compensatory mechanisms in tissues such as an increased anabolic signaling in muscle or an increased compliance of the vascular system. Accordingly, regular exercise training seems to protect long-term smokers against some important negative local and systemic consequences of smoking. Data suggest that it seems to be important to start exercise training as early as possible.

Murine models of cardiovascular comorbidity in chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) have an increased risk for cardiovascular disease (CVD). Currently, COPD patients with atherosclerosis (i.e., the most important underlying cause of CVD) receive COPD therapy complemented with standard CVD therapy. This may, however, not be the most optimal treatment. To investigate the link between COPD and atherosclerosis and to develop specific therapeutic strategies for COPD patients with atherosclerosis, a substantial number of preclinical studies using murine models have been performed. In this review, we summarize the currently used murine models of COPD and atherosclerosis, both individually and combined, and discuss the relevance of these models for studying the pathogenesis and development of new treatments for COPD patients with atherosclerosis. Murine and clinical studies have provided complementary information showing a prominent role for systemic inflammation and oxidative stress in the link between COPD and atherosclerosis. These and other studies showed that murine models for COPD and atherosclerosis are useful tools and can provide important insights relevant to understanding the link between COPD and CVD. More importantly, murine studies provide good platforms for studying the potential of promising (new) therapeutic strategies for COPD patients with CVD.

Effects of blue light phototherapy on DNA integrity in preterm newborns

In previous studies, exposure to phototherapy, but not oxygen therapy, resulted in damage to genetic material in newborns. The objective of this study was to determine whether micronucleated erythrocytes (MNE) increased in preterm newborns (PNBs) who were exposed to blue light phototherapy lamps. MNE of mature organisms are rapidly eliminated by the spleen, and the presence of MNE has been related to immaturity in some species. Furthermore, PNBs present spontaneous MNE. Blood samples were taken from 17 PNBs at birth to establish baseline frequencies (0 h). After beginning blue light phototherapy, blood samples were obtained from 11 of these PNBs at 24-h intervals for 96 h, after the baseline sample. MNE and micronucleated polychromatic erythrocytes (MNPCE) were counted. The basal values of MNE and MNPCE from 17 PNBs were 0.62 ± 0.48 and 1.52 ± 1.28 (‰), respectively, and no increase in MNE or MNPCE was observed in the serial samples of 11 PNBs exposed to blue light and oxygen therapies, though previous studies reported increases using other types of lamps. In conclusion, under the conditions described no increase in the number of MNE or MNPCE was observed in the peripheral blood of PNBs exposed to blue light phototherapy.

Systemic effects of acute cigarette smoke exposure in mice

CONTEXT

Cigarette smoke (CS) causes both pulmonary and extrapulmonary disorders.

OBJECTIVE

To determine the pulmonary and extrapulmonary effects of acute CS exposure in regard to inflammation, oxidative stress and DNA damage.

MATERIALS AND METHODS

Mice were exposed to CS for 10 days and then their lungs, heart, liver, pancreas, kidneys, gastrocnemius muscle and subcutaneous (inguinal and flank) and visceral (retroperitoneum and periuterus) adipose tissues were excised. Bronchoalveolar lavage fluid samples were obtained for differential cell analysis. Inflammatory cell infiltration of the tissues was assessed by immunohistochemistry for Mac-3(+) cells, F4/80(+) cells and CD45(+) cells. Oxidative stress was determined by immunohistochemistry for thymidine glycol (a marker of DNA peroxidation) and 4-hydroxy hexenal (a marker of lipid peroxidation), by enzyme-linked immunosorbent assay for protein carbonyls (a marker of protein peroxidation) and by measurements of enzyme activities of glutathione peroxidase, superoxide dismutase and catalase. DNA double-strand breaks were assessed by immunohistochemistry for γH2AX.

RESULTS

CS exposure-induced inflammatory cell infiltration, oxidative stress and DNA damage in the lung. Neither inflammatory cell infiltration nor DNA damage was observed in any extrapulmonary organs. However, oxidative stress was increased in the heart and inguinal adipose tissue.

DISCUSSIONS

Induction of inflammatory cell infiltration and DNA damage by acute CS exposure was confined to the lung. However, an increased oxidative burden occurred in the heart and some adipose tissue, as well as in the lung.

CONCLUSIONS

Although extrapulmonary effects of CS are relatively modest compared with the pulmonary effects, some extrapulmonary organs are vulnerable to CS-induced oxidative stress.

Acute effects of using an electronic nicotine-delivery device (electronic cigarette) on myocardial function: comparison with the effects of regular cigarettes

Background

Electronic cigarettes have been developed and marketed in recent years as smoking substitutes. However, no studies have evaluated their effects on the cardiovascular system. The purpose of this study was to examine the immediate effects of electronic cigarette use on left ventricular (LV) function, compared to the well-documented acute adverse effects of smoking.

Methods

Echocardiographic examinations were performed in 36 healthy heavy smokers (SM, age 36 ± 5 years) before and after smoking 1 cigarette and in 40 electronic cigarette users (ECIG, age 35 ± 5 years) before and after using the device with “medium-strength” nicotine concentration (11 mg/ml) for 7 minutes. Mitral flow diastolic velocities (E, A), their ratio (E/A), deceleration time (DT), isovolumetric relaxation time (IVRT) and corrected-to-heart rate IVRT (IVRTc) were measured. Mitral annulus systolic (Sm), and diastolic (Em, Am) velocities were estimated. Myocardial performance index was calculated from Doppler flow (MPI) and tissue Doppler (MPIt). Longitudinal deformation measurements of global strain (GS), systolic (SRs) and diastolic (SRe, SRa) strain rate were also performed.

Results

Baseline measurements were similar in both groups. In SM, IVRT and IVRTc were prolonged, Em and SRe were decreased, and both MPI and MPIt were elevated after smoking. In ECIG, no differences were observed after device use. Comparing after-use measurements, ECIG had higher Em (P = 0.032) and SRe (P = 0.022), and lower IVRTc (P = 0.011), MPI (P = 0.001) and MPIt (P = 0.019). The observed differences were significant even after adjusting for changes in heart rate and blood pressure.

Conclusions

Although acute smoking causes a delay in myocardial relaxation, electronic cigarette use has no immediate effects. Electronic cigarettes’ role in tobacco harm reduction should be studied intensively in order to determine whether switching to electronic cigarette use may have long-term beneficial effects on smokers’ health.

Trial registration

Current Controlled Trials ISRCTN16974547

Comparison of the cytotoxic potential of cigarette smoke and electronic cigarette vapour extract on cultured myocardial cells

BACKGROUND

Electronic cigarettes (ECs) have been marketed as an alternative-to-smoking habit. Besides chemical studies of the content of EC liquids or vapour, little research has been conducted on their in vitro effects. Smoking is an important risk factor for cardiovascular disease and cigarette smoke (CS) has well-established cytotoxic effects on myocardial cells. The purpose of this study was to evaluate the cytotoxic potential of the vapour of 20 EC liquid samples and a "base" liquid sample (50% glycerol and 50% propylene glycol, with no nicotine or flavourings) on cultured myocardial cells. Included were 4 samples produced by using cured tobacco leaves in order to extract the tobacco flavour.

METHODS

Cytotoxicity was tested according to the ISO 10993-5 standard. By activating an EC device at 3.7 volts (6.2 watts-all samples, including the "base" liquid) and at 4.5 volts (9.2 watts-four randomly selected samples), 200 mg of liquid evaporated and was extracted in 20 mL of culture medium. Cigarette smoke (CS) extract from three tobacco cigarettes was produced according to ISO 3308 method (2 s puffs of 35 mL volume, one puff every 60 s). The extracts, undiluted (100%) and in four dilutions (50%, 25%, 12.5%, and 6.25%), were applied to myocardial cells (H9c2); percent-viability was measured after 24 h incubation. According to ISO 10993-5, viability of <70% was considered cytotoxic.

RESULTS

CS extract was cytotoxic at extract concentrations >6.25% (viability: 76.9 ± 2.0% at 6.25%, 38.2 ± 0.5% at 12.5%, 3.1 ± 0.2% at 25%, 5.2 ± 0.8% at 50%, and 3.9 ± 0.2% at 100% extract concentration). Three EC extracts (produced by tobacco leaves) were cytotoxic at 100% and 50% extract concentrations (viability range: 2.2%-39.1% and 7.4%-66.9% respectively) and one ("Cinnamon-Cookies" flavour) was cytotoxic at 100% concentration only (viability: 64.8 ± 2.5%). Inhibitory concentration 50 was >3 times lower in CS extract compared to the worst-performing EC vapour extract. For EC extracts produced by high-voltage and energy, viability was reduced but no sample was cytotoxic according to ISO 10993-5 definition. Vapour produced by the "base" liquid was not cytotoxic at any extract concentration. Cell survival was not associated with nicotine concentration of EC liquids.

CONCLUSIONS

This study indicates that some EC samples have cytotoxic properties on cultured cardiomyoblasts, associated with the production process and materials used in flavourings. However, all EC vapour extracts were significantly less cytotoxic compared to CS extract.

Acute and chronic effects of smoking on myocardial function in healthy heavy smokers: a study of Doppler flow, Doppler tissue velocity, and two-dimensional speckle tracking echocardiography

BACKGROUND

The purpose of the study was to evaluate the acute and chronic effect of smoking on left ventricular function in healthy heavy smokers by conventional Doppler flow, tissue Doppler, and two-dimensional speckle tracking echocardiography (2D-STE).

METHODS

Echocardiograms were performed in 42 healthy heavy (>20 cigarettes/day) smokers (age 34 ± 5 years), before (group SM-1), 15 minutes (SM-2) and 30 minutes (SM-3) after starting smoking 2 cigarettes. Nonsmokers (n = 41, age 33 ± 4 years) served as controls. Transmitral flow, isovolumetric relaxation time (IVRT), and myocardial performance index (MPI) were measured. Tissue velocity measurements were averaged from lateral and septal mitral annulus. Longitudinal strain (GS), systolic (SRs), early diastolic (SRe), late diastolic (SRa), and isovolumetric relaxation (SRivr) strain rate were measured. The percent change in strain from end-systole to the first one-third of diastole (SI-DI = [(GS - strain at one-third diastole)/GS] × 100) was also measured.

RESULTS

IVRT and MPI were increased and early diastolic mitral annular velocity was decreased in SM-2; they returned to baseline in SM-3. There was no difference in GS and SRs. SRe and SRivr were reduced in SM-1 (P < 0.05), and remained significantly reduced in SM-2 and SM-3. SI-DI was lower in SM-1 (P = 0.011) and was further reduced in SM-2 and SM-3 (P < 0.001).

CONCLUSION

Acute and chronic smoking inhalation has adverse effects on myocardial function in healthy heavy smokers. 2D-STE is able to detect both baseline differences and late acute effects of smoking.

Polymorphisms of DNA repair pathway genes and cigarette smoking in relation to susceptibility to large artery atherosclerotic stroke among ethnic Chinese in Taiwan

AIM

Cigarette-smoking induced oxidative DNA damage to endothelial cells has been reported to play an etiological role in atherosclerosis development. Individual vulnerability to oxidative stress through smoking exposure and the ability to repair DNA damage, which plays a critical role in modifying the risk susceptibility of large artery atherosclerotic (LAA) stroke, is hypothesized. Thus, we examined the effect of genetic polymorphisms of DNA repair pathway genes and cigarette smoking in relation to risk susceptibility of LAA stroke.

METHODS

We enrolled 116 LAA stroke patients and 315 healthy controls from the Armed Forces Taoyuan General Hospital, Taoyuan, Taiwan. Genotyping of polymorphisms of the OGG1 (Ser326Cys), XRCC1 (Arg399Gln), ERCC2 (Lys751Gln), and ERCC5 (Asp1104His) genes was performed and used to evaluate LAA stroke susceptibility.

RESULTS

Of those non-synonymous polymorphisms, the ERCC2 Lys751Gln variant was found to be associated with LAA stroke risk (OR: 1.69, 95%CI: 1.02-2.86), and this association was more pronounced in smokers, manifesting a 2.73-fold increased risk of LAA stroke (p=0.027). A joint effect on risk elevation of LAA stroke was seen in those patients with OGG1 and ERCC2 polymorphisms (OR: 2.75, 95%CI: 1.26-6.00). Moreover, among smokers carrying the OGG1 Ser326Cys polymorphism, there was a tendency toward an increased risk of LAA stroke in those patients who had a greater number of high-risk genotypes of XRCC1, ERCC2, and ERCC5 polymorphisms (p(trend)=0.010).

CONCLUSION

The susceptible polymorphisms of DNA repair pathway genes may have a modifying effect on the elevated risk of LAA stroke in smokers among ethnic Chinese in Taiwan.

Adenylate kinase 3 sensitizes cells to cigarette smoke condensate vapor induced cisplatin resistance

BACKGROUND

The major established etiologic risk factor for bladder cancer is cigarette smoking and one of the major antineoplastic agents used for the treatment of advanced bladder cancer is cisplatin. A number of reports have suggested that cancer patients who smoke while receiving treatment have lower rates of response and decreased efficacy of cancer therapies.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we investigated the effect of cigarette smoke condensate (CSC) vapor on cisplatin toxicity in urothelial cell lines SV-HUC-1 and SCaBER cells. We showed that chronic exposure to CSC vapor induced cisplatin resistance in both cell lines. In addition, we found that the expression of mitochondrial-resident protein adenylate kinase-3 (AK3) is decreased by CSC vapor. We further observed that chronic CSC vapor-exposed cells displayed decreased cellular sensitivity to cisplatin, decreased mitochondrial membrane potential (ΔΨm) and increased basal cellular ROS levels compared to unexposed cells. Re-expression of AK3 in CSC vapor-exposed cells restored cellular sensitivity to cisplatin. Finally, CSC vapor increased the growth of the tumors and also curtail the response of tumor cells to cisplatin chemotherapy in vivo.

CONCLUSIONS/SIGNIFICANCE

The current study provides evidence that chronic CSC vapor exposure affects AK3 expression and renders the cells resistant to cisplatin.

In-vivo data on the influence of tobacco smoke and UV light on murine skin

Inhaled tobacco smoke comes in direct contact with few organs such as mouth, lungs, and stomach. Cigarette smoke (CS) in lungs has been extensively studied. However, limited data exist on its effect on skin, and there are no long-term experimental studies suggesting toxic effects on skin. Even though it is generally accepted that CS is among the main factors of skin aging, the number of experimental studies showing this aging effect is limited. We hereby studied the effect of long-term exposure to CS on the skin of hairless mice in combination with or without ultraviolet (UV) light. In addition, we investigated potential skin protection by a potent antioxidant namely procyanidine-rich French maritime pine bark extract (PBE) pycnogenol. Male and female hairless SKH-2 mice were exposed for 10 months to tobacco smoke and/or UV light in vivo, and their effects on skin were investigated. Some biophysical parameters such as development of erythema, transepidermal water loss (TEWL), and skin elasticity were measured. The results show that UV and CS may be acting synergistically, as shown by the enhanced TEWL, erythema values, epitheliomas, and squamous cell carcinomas (SCCs) observed, whereas PBE seems to protect skin against SCC.

Chronic cigarette smoking affects left and right ventricular long-axis function in healthy young subjects: a Doppler myocardial imaging study

OBJECTIVE

Cigarette smoking is one of the major risk factors for coronary artery disease. However, chronic smoking has additional cardiac adverse effects independent of coronary atherosclerosis. We assessed the possible effects of chronic smoking on left and right ventricular (LV, RV) long-axis function using Doppler myocardial imaging (DMI).

METHODS

Forty otherwise healthy smokers (mean age = 26+/-3 years) and 40 age-matched nonsmoking controls enrolled. Standard echocardiography protocol was followed by DMI. Peak systolic (V(S)), early (V(E)) and late diastolic (V(A)) velocities, peak systolic strain (S), and strain rate (SR) were measured from septal, lateral, and RV free walls.

RESULTS

The baseline characteristics of two groups were similar. There were significant differences regarding Doppler myocardial velocity, S, and SR indices. Septal V(E) (P < 0.04), S (P < 0.0001) and SR (P < 0.02) were significantly reduced in smokers. For both lateral and RV free wall, V(S) (P < 0.003, P < 0.002, respectively), V(E) (P < 0.0001, P < 0.002, respectively), S (P < 0.0001 for both), and SR (P < 0.0001, P < 0.002, respectively) were significantly reduced in smokers. There were significant correlations between the amount of smoking and septal, lateral, and RV free wall S and SR.

CONCLUSIONS

Chronic cigarette smoking causes alterations in long-axis systolic and diastolic functions of right and left ventricles in healthy young subjects. These changes can be accurately detected with Doppler myocardial velocity and SR imaging.

Prenatal N-acetylcysteine prevents cigarette smoke-induced lung cancer in neonatal mice

Certain adult diseases may have their origin early in life, and perinatal exposures may contribute to cancers both during childhood and later in life. We recently demonstrated that mainstream cigarette smoke (MCS) induces a potent carcinogenic response in mice when exposure starts soon after birth. We also showed that the antioxidant N-acetylcysteine (NAC) prevents the extensive nucleotide and gene expression alterations that occur 'physiologically' at birth in mouse lung. The present study was designed to evaluate whether administration of NAC during pregnancy may affect the yield of tumors in mice exposed to MCS, starting after birth and continuing for 120 days. The results obtained showed that 210 days after birth, one adenoma only was detectable in sham-exposed mice. In contrast, as much as the 61.1% (33/54) of MCS-exposed mice born from untreated dams had lung tumors, including both benign tumors and bronchoalveolar carcinomas. Treatment with NAC during pregnancy strikingly inhibited the formation of benign lung tumors and totally prevented occurrence of carcinomas. In addition, prenatal NAC inhibited the MCS-induced hyperplasia of the urinary bladder epithelium. These findings demonstrate for the first time that treatment during pregnancy with an antioxidant chemopreventive agent can affect the induction of tumors consequent to exposure to a carcinogen after birth.

Preneoplastic and neoplastic lesions in the lung, liver and urinary tract of mice exposed to environmental cigarette smoke and UV light since birth

It is difficult to reproduce the carcinogenicity of cigarette smoke (CS) in animal models. Recently, we showed that exposure of mice to mainstream CS (MCS) for 120 days, starting immediately after birth, resulted in an early and potent carcinogenic response. In parallel, we implemented studies evaluating intermediate biomarkers and tumors in mice exposed to environmental CS (ECS). To this purpose, we used 263 newborn CD-1 mice born from 27 dams. The whole-body exposure to ECS for 120 days, starting within 12 hr after birth, resulted in an early appearance of preneoplastic lesions in lung, which however tended to attenuate after discontinuing exposure. When the experiment was stopped, after 330 days, the number of lung adenomas was higher in ECS-exposed mice as compared to sham-exposed mice, but such increase was statistically significant only in mice co-exposed to smoke and halogen light mimicking solar irradiation. Moreover, exposure to ECS produced extensive histopathological changes, mainly parenchymatous degeneration, in liver. The alterations produced in both lung and liver require that exposure to ECS starts immediately after birth, no effect being observed when exposure started 8 days later. In contrast, induction by ECS of alterations in the urinary tract, such as microadenomas and adenomas in renal pelvis and kidney, papillary hyperplasia of urothelium, and urinary bladder papillomas, were unrelated to the exposure time after birth. The results obtained with ECS cannot be directly compared to those previously obtained with MCS, since the latter involved shorter daily exposures to more massive CS doses.