Environmental tobacco smoke suppresses nuclear factor-kappaB signaling to increase apoptosis in infant monkey lungs

Chlorogenic acid and intestinal health: mechanistic insights and therapeutic applications

Chlorogenic acid (CGA), a polyphenolic compound found in various plant species, has shown considerable potential in the treatment and management of several diseases due to its potent bioactive properties. Increasing evidence indicates that CGA exerts significant antioxidant, anti-inflammatory, and immunomodulatory effects by modulating key signaling pathways, including MAPK, PTEN/Akt, STAT3, and NF-κB/NLRP3. Furthermore, CGA enhances intestinal barrier function and positively influences the gut microbiota composition, making it a promising natural therapeutic agent for conditions such as inflammatory bowel disease, irritable bowel syndrome, and colorectal cancer. This review provides a comprehensive summary of the most recent research on CGA's role in managing intestinal disorders. It first discusses CGA's chemical structure and pharmacokinetics (including absorption and metabolism), followed by an in-depth analysis of the mechanisms through which CGA mediates its therapeutic effects. These insights aim to advance our understanding of CGA's therapeutic potential in treating intestinal diseases.

Acetylsalicylic acid reduces cigarette smoke withdrawal-induced anxiety in rats via modulating the expression of NFĸB, GLT-1, and xCT

Background: Chronic exposure to cigarette smoke produces neuroinflammation and long-term changes in neurotransmitter systems, especially glutamatergic systems. Objective: We examined the effects of cigarette smoke on astroglial glutamate transporters as well as NF-κB expression in mesocorticolimbic brain regions, prefrontal cortex (PFC) and nucleus accumbens (NAc). The behavioral consequences of cigarette smoke exposure were assessed using open field (OF) and light/dark (LD) tests to assess withdrawal-induced anxiety-like behavior. Methods: Sprague-Dawley rats were randomly assigned to five experimental groups: a control group exposed only to standard room air, a cigarette smoke exposed group treated with saline vehicle, two cigarette smoke exposed groups treated with acetylsalicylic acid (ASA) (15 mg/kg and 30 mg/kg, respectively), and a group treated only with ASA (30 mg/kg). Cigarette smoke exposure was performed for 2 h/day, 5 days/week, for 31 days. Behavioral tests were conducted weekly, 24 h after cigarette smoke exposure, during acute withdrawal. At the end of week 4, rats were given either saline or ASA 45 min before cigarette exposure for 11 days. Results: Cigarette smoke increased withdrawal-induced anxiety, and 30 mg/kg ASA attenuated this effect. Cigarette smoke exposure increased the relative mRNA and protein expression of nuclear factor ĸB (NFĸB) in PFC and NAc, and ASA treatment reversed this effect. Also, cigarette smoke decreased the relative mRNA and protein expression of glutamate transporter1 (GLT-1) and the cystine-glutamate transporter (xCT) in the PFC and the NAc, while ASA treatment normalized their expression. Conclusion: Cigarette smoke caused neuroinflammation, alterations in glutamate transporter expression, and increased anxiety-like behavior, and these effects were attenuated by acetylsalicylic acid treatment.

Cigarette Smoke Exposure Inhibits Early Phase of Antibody Production through Inhibition of Immune Functions in Alveolar Macrophage

Background::

Cigarette smoke (CS) is inhaled into the lung. Alveolar macrophage (AM) is known to play an important role in the lung immune system. However, the relationship between AM functions and antibody production by CS is not fully investigated.

Objective::

Therefore, we investigated the effects of AM from CS exposed mice on antibody production. Mice were exposed to 20 cigarettes/day for 10 days. AM were obtained by broncho-alveolar lavage. Antibody production was analyzed by plaque-forming cell assay using seep red blood cell (SRBC) as antigen.

Methods::

B cell proliferation was analyzed by 3H-thymidine incorporation. Phagocytic activity using fluorescein isothiocyanate-labeled SRBC and expressions of surface antigens on AM were analyzed by flow cytometry. Cytokines and NF-κB mRNA expressions of AM were analyzed by RTPCR.

Results and Discussion:

Antibody production was decreased at the induction phase, but not at the expression phase by AM from smoked mice (SM) compared with non-smoked mice (NSM). B cell proliferation was decreased by cigarette extracts dose-dependently. Phagocytic activity of AM was decreased in SM compared with NSM. Expression of surface antigens on AM was decreased in SM compared with NSM. Cytokines or NF-κB mRNA expressions of AM were decreased in SM compared with NSM.

Conclusion::

These results suggest that the inhibition of antibody production by cigarette smoking is caused by the inhibition of phagocytosis and expressions of surface antigens associated with antigen presentation. Such inhibition of AM functions may increase the risk of bacterial and virus infections.

Changes in DNA methylation from pre- to post-adolescence are associated with pubertal exposures

BACKGROUND

Adolescence is a period characterized by major biological development, which may be associated with changes in DNA methylation (DNA-M). However, it is unknown to what extent DNA-M varies from pre- to post-adolescence, whether the pattern of changes is different between females and males, and how adolescence-related factors are associated with changes in DNA-M.

METHODS

Genome-scale DNA-M at ages 10 and 18 years in whole blood of 325 subjects (n = 140 females) in the Isle of Wight (IOW) birth cohort was analyzed using Illumina Infinium arrays (450K and EPIC). Linear mixed models were used to examine DNA-M changes between pre- and post-adolescence and whether the changes were gender-specific. Adolescence-related factors and environmental exposure factors were assessed on their association with DNA-M changes. Replication of findings was attempted in the comparable Avon Longitudinal Study of Parents and Children (ALSPAC) cohort.

RESULTS

In the IOW cohort, after controlling for technical variation and cell compositions at both pre- and post-adolescence, 15,532 cytosine-phosphate-guanine (CpG) sites (of 400,825 CpGs, 3.88%) showed statistically significant DNA-M changes from pre-adolescence to post-adolescence invariant to gender (false discovery rate (FDR) = 0.05). Of these 15,532 CpGs, 10,212 CpGs (66%) were replicated in the ALSPAC cohort. Pathway analysis using Ingenuity Pathway Analysis (IPA) identified significant biological pathways related to growth and development of the reproductive system, emphasizing the importance of this period of transition on epigenetic state of genes. In addition, in IOW, we identified 1179 CpGs with gender-specific DNA-M changes. In the IOW cohort, body mass index (BMI) at age 10 years, age of growth spurt, nonsteroidal drugs use, and current smoking status showed statistically significant associations with DNA-M changes at 15 CpGs on 14 genes such as the AHRR gene. For BMI at age 10 years, the association was gender-specific. Findings on current smoking status were replicated in the ALSPAC cohort.

CONCLUSION

Adolescent transition is associated with changes in DNA-M at more than 15K CpGs. Identified pathways emphasize the importance of this period of transition on epigenetic state of genes relevant to cell growth and immune system development.

Nonhuman Primate Models of Respiratory Disease: Past, Present, and Future

The respiratory system consists of an integrated network of organs and structures that primarily function for gas exchange. In mammals, oxygen and carbon dioxide are transmitted through a complex respiratory tract, consisting of the nasal passages, pharynx, larynx, and lung. Exposure to ambient air throughout the lifespan imposes vulnerability of the respiratory system to environmental challenges that can contribute toward development of disease. The importance of the respiratory system to human health is supported by statistics from the Centers for Disease Control and Prevention; in 2015, chronic lower respiratory diseases were the third leading cause of death in the United States. In light of the significant mortality associated with respiratory conditions that afflict all ages of the human population, this review will focus on basic and preclinical research conducted in nonhuman primate models of respiratory disease. In comparison with other laboratory animals, the nonhuman primate lung most closely resembles the human lung in structure, physiology, and mucosal immune mechanisms. Studies defining the influence of inhaled microbes, pollutants, or allergens on the nonhuman primate lung have provided insight on disease pathogenesis, with the potential for elucidation of molecular targets leading to new treatment modalities. Vaccine trials in nonhuman primates have been crucial for confirmation of safety and protective efficacy against infectious diseases of the lung in a laboratory animal model that recapitulates pathology observed in humans. In looking to the future, nonhuman primate models of respiratory diseases will continue to be instrumental for translating biomedical research for improvement of human health.

Secondhand Smoking Is Associated With Vascular Inflammation

BACKGROUND

The relative risk for cardiovascular diseases in passive smokers is similar to that of active smokers despite almost a 100-fold lower dose of inhaled cigarette smoke. However, the mechanisms underlying the surprising susceptibility of the vascular tissue to the toxins in secondhand smoke (SHS) have not been directly investigated. The aim of this study was to investigate directly vascular endothelial cell function in passive smokers.

METHODS

Using a minimally invasive method of endothelial biopsy, we investigated directly the vascular endothelium in 23 healthy passive smokers, 25 healthy active smokers, and 23 healthy control subjects who had never smoked and had no regular exposure to SHS. Endothelial nitric oxide synthase (eNOS) function (expression of basal eNOS and activated eNOS [phosphorylated eNOS at serine1177 (P-eNOS)]) and expression of markers of inflammation (nuclear factor-κB [NF-κB]) and oxidative stress (nitrotyrosine) were assessed in freshly harvested venous endothelial cells by quantitative immunofluorescence.

RESULTS

Expression of eNOS and P-eNOS was similarly reduced and expression of NF-κB was similarly increased in passive and active smokers compared with control subjects. Expression of nitrotyrosine was greater in active smokers than control subjects and similar in passive and active smokers. Brachial artery flow-mediated dilation was similarly reduced in passive and active smokers compared with control subjects, consistent with reduced endothelial NO bioavailability.

CONCLUSIONS

Secondhand smoking increases vascular endothelial inflammation and reduces active eNOS to a similar extent as active cigarette smoking, indicating direct toxic effects of SHS on the vasculature.

Cigarette smoke induced airway inflammation is independent of NF-κB signalling

RATIONALE

COPD is an inflammatory lung disease largely associated with exposure to cigarette smoke (CS). The mechanism by which CS leads to the pathogenesis of COPD is currently unclear; it is known however that many of the inflammatory mediators present in the COPD lung can be produced via the actions of the transcription factor Nuclear Factor-kappaB (NF-κB) and its upstream signalling kinase, Inhibitor of κB kinase-2 (IKK-2). Therefore the NF-κB/IKK-2 signalling pathway may represent a therapeutic target to attenuate the inflammation associated with COPD.

AIM

To use a range of assays, genetically modified animals and pharmacological tools to determine the role of NF-κB in CS-induced airway inflammation.

METHODS

NF-κB pathway activation was measured in pre-clinical models of CS-induced airway inflammation and in human lung tissue from COPD patients. This data was complemented by employing mice missing a functional NF-κB pathway in specific cell types (epithelial and myeloid cells) and with systemic inhibitors of IKK-2.

RESULTS

We showed in an airway inflammation model known to be NF-κB-dependent that the NF-κB pathway activity assays and modulators were functional in the mouse lung. Then, using the same methods, we demonstrated that the NF-κB pathway appears not to play an important role in the inflammation observed after exposure to CS. Furthermore, assaying human lung tissue revealed that in the clinical samples there was also no increase in NF-κB pathway activation in the COPD lung, suggesting that our pre-clinical data is translational to human disease.

CONCLUSIONS

In this study we present compelling evidence that the IKK-2/NF-κB signalling pathway does not play a prominent role in the inflammatory response to CS exposure and that this pathway may not be important in COPD pathogenesis.

MetaMapp: mapping and visualizing metabolomic data by integrating information from biochemical pathways and chemical and mass spectral similarity

BACKGROUND

Exposure to environmental tobacco smoke (ETS) leads to higher rates of pulmonary diseases and infections in children. To study the biochemical changes that may precede lung diseases, metabolomic effects on fetal and maternal lungs and plasma from rats exposed to ETS were compared to filtered air control animals. Genome- reconstructed metabolic pathways may be used to map and interpret dysregulation in metabolic networks. However, mass spectrometry-based non-targeted metabolomics datasets often comprise many metabolites for which links to enzymatic reactions have not yet been reported. Hence, network visualizations that rely on current biochemical databases are incomplete and also fail to visualize novel, structurally unidentified metabolites.

RESULTS

We present a novel approach to integrate biochemical pathway and chemical relationships to map all detected metabolites in network graphs (MetaMapp) using KEGG reactant pair database, Tanimoto chemical and NIST mass spectral similarity scores. In fetal and maternal lungs, and in maternal blood plasma from pregnant rats exposed to environmental tobacco smoke (ETS), 459 unique metabolites comprising 179 structurally identified compounds were detected by gas chromatography time of flight mass spectrometry (GC-TOF MS) and BinBase data processing. MetaMapp graphs in Cytoscape showed much clearer metabolic modularity and complete content visualization compared to conventional biochemical mapping approaches. Cytoscape visualization of differential statistics results using these graphs showed that overall, fetal lung metabolism was more impaired than lungs and blood metabolism in dams. Fetuses from ETS-exposed dams expressed lower lipid and nucleotide levels and higher amounts of energy metabolism intermediates than control animals, indicating lower biosynthetic rates of metabolites for cell division, structural proteins and lipids that are critical for in lung development.

CONCLUSIONS

MetaMapp graphs efficiently visualizes mass spectrometry based metabolomics datasets as network graphs in Cytoscape, and highlights metabolic alterations that can be associated with higher rate of pulmonary diseases and infections in children prenatally exposed to ETS. The MetaMapp scripts can be accessed at http://metamapp.fiehnlab.ucdavis.edu.

A cellular model to mimic exhaled cigarette smokeinduced lung microvascular endothelial cell injury and death

Tobacco smoke exhaled from smokers is a key component of secondhand smoke, contributing to lung alveolar wall destruction seen in chronic lung diseases. Although mainstream and sidestream tobacco smoke are cyto-toxic to lung cells, it is unclear whether exhaled smoke induces lung cell injury or even death. We sought to establish an in vitro model to examine the effects of exhaled smoke on lung cells. Phosphate-buffered saline-conditioned cigarette smoke (CCS) derived from a blow-by system was used to mimic exhaled tobacco smoke exposure. Exposure of medium to CCS leads to dose-dependent increases in nicotine/cotinine levels. Scanning spectrophotometric analysis of the CCS-exposed medium reveals an absorption peak at 290 nm wavelength. The OD values at 290 nm are correlated with nicotine levels in the exposed medium, indicating that a simple measurement of OD at 290 nm can be used to monitor CCS exposure. Tobacco smoke contacts the microvascular endothelium located at lung alveoli, before it enters the blood stream. Hence, human lung microvascular endothelial cells (hMVEC) were exposed to CCS and assessed for cell injury and death. Exposure of hMVEC to CCS equivalent to burning 12-16 cigarettes leads to increased LDH release from the cells into the medium. This suggests that CCS can induce lung cell injury. CCS at a low level increases cell growth, whereas the high level of CCS decreases cell viability. In addition, CCS exposure induces cell detachment and morphological changes. Our results demonstrate that exposure of buffer-conditioned mainstream cigarette smoke leads to increased nicotine/cotinine levels and cell injury/death, which may contribute to the pathophysiology of passive smoking-associated lung diseases.

Interactions among genetic variants in apoptosis pathway genes, reflux symptoms, body mass index, and smoking indicate two distinct etiologic patterns of esophageal adenocarcinoma

PURPOSE

Apoptosis pathway, gastroesophageal reflux symptoms (reflux), higher body mass index (BMI), and tobacco smoking have been individually associated with esophageal adenocarcinoma (EA) development. However, how multiple factors jointly affect EA risk remains unclear.

PATIENTS AND METHODS

In total, 305 patients with EA and 339 age- and sex-matched controls were studied. High-order interactions among reflux, BMI, smoking, and functional polymorphisms in five apoptotic genes (FAS, FASL, IL1B, TP53BP, and BAT3) were investigated by entropy-based multifactor dimensionality reduction (MDR), classification and regression tree (CART), and traditional logistic regression (LR) models.

RESULTS

In LR analysis, reflux, BMI, and smoking were significantly associated with EA risk, with reflux as the strongest individual factor. No individual single nucleotide polymorphism was associated with EA susceptibility. However, there was a two-way interaction between IL1B + 3954C>T and reflux (P = .008). In both CART and MDR analyses, reflux was also the strongest individual factor for EA risk. In individuals with reflux symptoms, CART analysis indicated that strongest interaction was among variant genotypes of IL1B + 3954C>T and BAT3S625P, higher BMI, and smoking (odds ratio [OR], 5.76; 95% CI, 2.48 to 13.38), a finding independently found using MDR analysis. In contrast, for participants without reflux symptoms, the strongest interaction was found between higher BMI and smoking (OR, 3.27; 95% CI, 1.88 to 5.68), also echoed by entropy-based MDR analysis.

CONCLUSION

Although a history of reflux is an important risk for EA, multifactor interactions also play important roles in EA risk. Gene-environment interaction patterns differ between patients with and without reflux symptoms.

Roles of oxidative stress in signaling and inflammation induced by particulate matter

This review reports the role of oxidative stress in impairing the function of lung exposed to particulate matter (PM). PM constitutes a heterogeneous mixture of various types of particles, many of which are likely to be involved in oxidative stress induction and respiratory diseases. Probably, the ability of PM to cause oxidative stress underlies the association between increased exposure to PM and exacerbations of lung disease. Mostly because of their large surface area, ultrafine particles have been shown to cause oxidative stress and proinflammatory effects in different in vivo and in vitro studies. Particle components and surface area may act synergistically inducing lung inflammation. In this vein, reactive oxygen species elicited upon PM exposure have been shown to activate a number of redox-responsive signaling pathways and Ca(2+) influx in lung target cells that are involved in the expression of genes that modulate relevant responses to lung inflammation and disease.

Effects of cigarette smoke on the activation of oxidative stress-related transcription factors in female A/J mouse lung

Cigarette smoke contains a high concentration of free radicals and induces oxidative stress in the lung and other tissues. Several transcription factors are known to be activated by oxidative stress, including nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1), and hypoxia-inducible factor (HIF). Studies were therefore undertaken to examine whether cigarette smoke could activate these transcription factors, as well as other transcription factors that may be important in lung carcinogenesis. Female A/J mice were exposed to cigarette smoke for 2, 5, 10, 15, 20, 42, or 56 d (6 hr/d, 5 d/wk). Cigarette smoke did not increase NF-kappaB activation at any of these times, but NF-kappaB DNA binding activity was lower after 15 d and 56 d of smoke exposure. The DNA binding activity of AP-1 was lower after 10 d and 56 d but was not changed after 42 d of smoke exposure. The DNA binding activity of HIF was quantitatively increased after 42 d of smoke exposure but decreased after 56 d. Whether the activation of other transcription factors in the lung could be altered after exposure to cigarette smoke was subsequently examined. The DNA binding activities of FoxF2, myc-CF1, RORE, and p53 were examined after 10 d of smoke exposure. The DNA binding activities of FoxF2 and p53 were quantitatively increased, but those of myc-CF1 and RORE were unaffected. These studies show that cigarette smoke exposure leads to quantitative increases in DNA binding activities of FoxF2 and p53, while the activations of NF-kappaB, AP-1, and HIF are largely unaffected or reduced.

In utero and postnatal exposure to environmental tobacco smoke (ETS) alters alveolar and respiratory bronchiole (RB) growth and development in infant monkeys

The direct effect of environmental tobacco smoke (ETS) exposure in utero on the development of the lung parenchyma is not known. We used design-based stereologic methods to evaluate in utero and postnatal ETS exposure on alveolar and respiratory bronchiole (RB) development in the rhesus macaque.

METHODS

Timed-pregnant rhesus macaques and their offspring were exposed to filtered air or various amounts of ETS during the prenatal and postnatal period. The left cranial lobe from necropsied infants was evaluated by design-based stereological methods and general pathological review.

RESULTS

Infants in the in utero and six-month ETS groups had an 18% and 17% relative decrease, respectively, in alveolar number and a 57% and 33% increase, respectively, in alveolar size compared to filtered air (FA) monkeys. Lung volume positively correlated with alveolar number in the FA and six-month ETS group and negatively correlated in the in utero ETS group. The distribution of alveolar size was much more variable in the in utero group. Overall, RB volume was significantly increased in the six-month ETS group (p < .04).

CONCLUSIONS

Taken together, these results indicate that in utero and postnatal ETS exposure is associated with altered parenchymal lung development.

Exposure to environmental tobacco smoke induces angiogenesis and leukocyte trafficking in lung microvessels

Exposure to environmental tobacco smoke (ETS) is known to contribute to and exacerbate inflammatory diseases of the lung such as chronic obstructive pulmonary disease (COPD) and asthma. The effect of ETS on angiogenesis and leukocyte recruitment, both of which promote lung inflammation, was investigated using lung tissue from mice exposed to aged and diluted sidestream cigarette smoke or fresh air for 12 weeks and transplanted into dorsal skin-fold chambers in nude mice. Lung tissue from mice exposed to cigarette smoke for 12 weeks exhibited significantly increased vascular density (angiogenesis) associated with selectin-mediated increased intravascular leukocyte rolling and adhesion compared to fresh air-exposed lung tissue by intravital microscopy. Further, neutrophils from nicotine-exposed mice displayed significantly increased rolling and adhesion compared to control neutrophils in microvessels of nicotine-exposed lungs versus control lung microvessels, suggesting that nicotine in cigarette smoke can augment leukocyte-endothelial interactions. ETS-induced angiogenesis and leukocyte trafficking may play a key role in airway recruitment of inflammatory cells in ETS-associated disorders such as COPD bronchitis or asthma.

Distinct pathophysiologic pathways induced by in vitro infection and cigarette smoke in normal human fetal membranes

OBJECTIVE

The purpose of this study was to document distinct pathways that are initiated by lipopolysaccharide and cigarette smoke stimulation of normal term fetal membranes.

STUDY DESIGN

Fetal membranes from nonsmoking women at term, not in labor, from cesarean deliveries were placed in an organ explant system and stimulated with cigarette smoke extracts (CSEs), lipopolysaccharide, or lipopolysaccharide + CSE. Media were assayed for an interleukin (IL)-1beta, -1 receptor antagonist, -6, -8, -10, tumor necrosis factor alpha, soluble tumor necrosis factor receptors 1 and 2, and matrix metalloproteinases 1, 2, 3, 8, 9, and 12. Tissue homogenates were assayed for apoptotic markers (p53, caspase 3 activity, and cleaved poly [ADP-ribose] polymerase-1).

RESULTS

Lipopolysaccharide stimulation resulted in higher cytokine and matrix metalloproteinase concentrations, whereas it was lower after CSE and CSE + lipopolysaccharide stimulations, compared with control specimens. Apoptotic factors were several folds higher after CSE or CSE + lipopolysaccharide stimulation, compared with control specimens or lipopolysaccharide stimulations.

CONCLUSION

Cigarette smoke showed immunoinhibitory properties that potentially were mediated by apoptosis and lipopolysaccharide-induced proinflammatory response. This study demonstrated 2 independent pathophysiologic pathways that may alter pregnancy outcome.

Identification of a cigarette smoke-responsive region in the distal MMP-1 promoter

Tobacco-related diseases are leading causes of death worldwide, and many are associated with expression of matrix metalloproteinase-1 (MMP-1). We have reported extracellular signal-regulated kinase (ERK)1/2-dependent induction of MMP-1 by cigarette smoke in lung epithelial cells. Our objectives were to define regions of the human MMP-1 promoter required for activation by smoke, to identify differences in responses of the 1G/2G -1607 polymorphic promoters to smoke, and to identify relevant transcription factors whose activity in airway epithelial cells is increased by smoke. The responses of deletion and mutant promoter constructs were measured in transfected cells during exposure to cigarette smoke extract (CSE). DNA oligonucleotide arrays were used to identify transcription factors activated after smoke exposure. CSE activated the MMP-1 promoter, and this induction was prevented by PD98059 blockade of ERK1/2 phosphorylation. Deletion studies revealed the distal 1kb promoter region (-4438 to -3280 upstream of the transcription start site) is essential for CSE induction of MMP-1, and confers activation of a minimal promoter. Studies of 1G and 2G MMP-1 polymorphic promoter variants revealed higher 2G allele basal and CSE-responsive activities than the 1G allele. Cotransfection, mithramycin, and electrophoretic mobility shift assay studies identified activating and repressive roles for Sp1 and PEA3 transcription factors, respectively. Oligonucleotide DNA arrays confirmed activation of Sp1 and PEA3 by CSE. These data demonstrate that the MMP-1 promoter is a direct target of cigarette smoke in lung epithelial cells. This characterization of a smoke response region in the distal MMP-1 promoter has implications for smoking-related diseases such as cancer, heart disease, and emphysema.

Effects of environmental tobacco smoke in vivo on rhesus monkey semen quality, sperm function, and sperm metabolism

The objective of this study was to use a non-human primate model to examine the effect of environmental tobacco smoke (ETS) in vivo on semen quality, sperm function, and sperm metabolism. Four adult rhesus macaques (Macaca mulatta) were exposed to ETS for six months, and semen samples were collected every week for evaluation. ETS exposure in vivo did not affect semen quality and sperm function. The sperm X:Y chromosome ratio remained unchanged after ETS exposure. The sex ratio of the embryos fertilized by ETS-exposed males was not different from the control male. However, sperm showed changes in metabolome detected by NMR during the ETS exposure. We concluded that with the duration and level of ETS exposure in this study, semen quality and sperm function were not affected, whereas sperm did undergo metabolic changes with ETS exposure in vivo.

Environmental toxicity, oxidative stress and apoptosis: ménage à trois

Apoptosis is an evolutionary conserved homeostatic process involved in distinct physiological processes including organ and tissue morphogenesis, development and senescence. Its deregulation is also known to participate in the etiology of several human diseases including cancer, neurodegenerative and autoimmune disorders. Environmental stressors (cytotoxic agents, pollutants or toxicants) are well known to induce apoptotic cell death and to contribute to a variety of pathological conditions. Oxidative stress seems to be the central element in the regulation of the apoptotic pathways triggered by environmental stressors. In this work, we review the established mechanisms by which oxidative stress and environmental stressors regulate the apoptotic machinery with the aim to underscore the relevance of apoptosis as a component in environmental toxicity and human disease progression.

NF-kappaB mediates the survival of human bronchial epithelial cells exposed to cigarette smoke extract

BACKGROUND

We have previously reported that low concentrations of cigarette smoke extract induce DNA damage without leading to apoptosis or necrosis in human bronchial epithelial cells (HBECs), and that IL-6/STAT3 signaling contributes to the cell survival. Since NF-kappaB is also involved in regulating apoptosis and cell survival, the current study was designed to investigate the role of NF-kappaB in mediating cell survival in response to cigarette smoke exposure in HBECs.

METHODS

Both the pharmacologic inhibitor of NF-kappaB, curcumin, and RNA interference targeting p65 were used to block NF-kappaB signaling in HBECs. Apoptosis and cell survival were then assessed by various methods including COMET assay, LIVE/DEAD Cytotoxicity/Viability assay and colony formation assay.

RESULTS

Cigarette smoke extract (CSE) caused DNA damage and cell cycle arrest in S phase without leading to apoptosis in HBECs as evidenced by TUNEL assay, COMET assay and DNA content assay. CSE stimulated NF-kappaB -DNA binding activity and up-regulated Bcl-XL protein in HBECs. Inhibition of NF-kappaB by the pharmacologic inhibitor curcumin (20 microM) or suppression of p65 by siRNA resulted in a significant increase in cell death in response to cigarette smoke exposure. Furthermore, cells lacking p65 were incapable of forming cellular colonies when these cells were exposed to CSE, while they behaved normally in the regular culture medium.

CONCLUSION

The current study demonstrates that CSE activates NF-kappaB and up-regulates Bcl-XL through NF-kB activation in HBECs, and that CSE induces cell death in cells lacking p65. These results suggest that activation of NF-kappaB regulates cell survival following DNA damage by cigarette smoke in human bronchial epithelial cells.

NF-kappaB inhibition is involved in tobacco smoke-induced apoptosis in the lungs of rats

Apoptosis is a vital mechanism for the regulation of cell turnover and plays a critical role in tissue homeostasis and development of many disease processes. Previous studies have demonstrated the apoptotic effect of tobacco smoke; however, the molecular mechanisms by which tobacco smoke triggers apoptosis remain unclear. In the present study we investigated the effects of tobacco smoke on the induction of apoptosis in the lungs of rats and modulation of nuclear factor-kappa B (NF-kappaB) in this process. Exposure of rats to 80 mg/m(3) tobacco smoke significantly induced apoptosis in the lungs. Tobacco smoke resulted in inhibition of NF-kappaB activity, noted by suppression of inhibitor of kappaB (IkappaB) kinase (IKK), accumulation of IkappaBalpha, decrease of NF-kappaB DNA binding activity, and downregulation of NF-kappaB-dependent anti-apoptotic proteins, including Bcl-2, Bcl-xl, and inhibitors of apoptosis. Initiator caspases for the death receptor pathway (caspase 8) and the mitochondrial pathway (caspase 9) as well as effector caspase 3 were activated following tobacco smoke exposure. Tobacco smoke exposure did not alter the levels of p53 and Bax proteins. These findings suggest the role of NF-kappaB pathway in tobacco smoke-induced apoptosis.

Molecular pathogenesis of emphysema

Emphysema is one manifestation of a group of chronic, obstructive, and frequently progressive destructive lung diseases. Cigarette smoking and air pollution are the main causes of emphysema in humans, and cigarette smoking causes emphysema in rodents. This review examines the concept of a homeostatically active lung structure maintenance program that, when attacked by proteases and oxidants, leads to the loss of alveolar septal cells and airspace enlargement. Inflammatory and noninflammatory mechanisms of disease pathogenesis, as well as the role of the innate and adaptive immune systems, are being explored in genetically altered animals and in exposure models of this disease. These recent scientific advances support a model whereby alveolar destruction resulting from a coalescence of mechanical forces, such as hyperinflation, and more recently recognized cellular and molecular events, including apoptosis, cellular senescence, and failed lung tissue repair, produces the clinically recognized syndrome of emphysema.

Concentrations of the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in sidestream cigarette smoke increase after release into indoor air: results from unpublished tobacco industry research

Research has shown that the toxicity of sidestream cigarette smoke, the primary constituent of secondhand smoke, increases over time. To find potential mechanisms that would explain the increase in sidestream smoke toxicity over time, we analyzed unpublished research reports from Philip Morris Co. using the internal tobacco industry documents now available at the University of California San Francisco Legacy Tobacco Documents Library and other Web sites. Unpublished research from Philip Morris Tobacco Company shows that 4-(methylnitrosamino)-I-(3-pyridyl)-1-butanone (NNK), a highly carcinogenic tobacco-specific nitrosamine, can form in sidestream cigarette smoke after it has been released into ambient air. In experiments done between 1983 and 1997, Philip Morris scientists measured the concentration of NNK in sidestream smoke in a sealed stainless steel test chamber at initial particle concentrations of 24 mg/m(3) over the course of 6 to 18 h. They repeatedly showed that airborne NNK concentrations in sidestream cigarette smoke can increase by 50% to 200% per hour during the first 6 h after cigarettes are extinguished. Two experiments done in a real office showed that NNK concentrations increase for the first 2 h after cigarettes are extinguished. If NNK formation also occurs in the lower smoke concentrations observed in real smoking environments, these results suggest that nitrosation of nicotine and/or nicotine breakdown products in aging secondhand smoke is a significant contributor to nitrosamine exposure in humans.

Effects of environmental tobacco smoke on the developing immune system of infant monkeys

BACKGROUND

Exposure to environmental tobacco smoke (ETS) is associated with an increased incidence of allergic and infectious diseases among children that is thought to be partly due to the immaturity of the immune system.

OBJECTIVE

We sought to investigate the effects of ETS exposure on immune development during the first year of life in the nonhuman primate.

METHODS

Fifteen neonatal rhesus monkeys studied to 13 months of postnatal age were randomized into 3 groups: (1) exposure to filtered air, (2) continuous ETS exposure beginning at gestation day 50 (perinatal ETS); and (3) exposure to ETS beginning at 6 months of age (6-month ETS). Complete blood counts, lymphocyte subsets, and mRNA levels of 12 cytokines in PBMCs were measured.

RESULTS

Fetal/infant exposure to ETS altered the normal maturation of mRNA levels of IFN-gamma, IL-2, and IL-10, as well as the ratio of CD4 to CD8 lymphocytes, compared with filtered-air control levels. Blood lymphocyte subset distribution also significantly differed based on the onset of exposure to ETS. Subacute exposure to ETS for 2 weeks in 6-month-old infants was found to increase levels of peripheral blood neutrophils and IL-6 mRNA.

CONCLUSIONS

Short-term exposure to ETS can induce an acute systemic inflammatory response in the neonatal nonhuman primate, and long-term exposure to ETS beginning in utero or at 6 months of postnatal age can significantly alter immune effectors.

CLINICAL IMPLICATIONS

Normal immune system development is compromised by in utero and postnatal exposure to ETS and might contribute to ETS-related childhood diseases.

Pathobiology of cigarette smoke-induced chronic obstructive pulmonary disease

Chronic obstructive pulmonary diseases (COPD), comprised of pulmonary emphysema, chronic bronchitis, and structural and inflammatory changes of small airways, is a leading cause of morbidity and mortality in the world. A better understanding of the pathobiology of COPD is critical for the developing of novel therapies, as the majority of patients with the disease have little therapeutic options at the present time. The pathobiology of COPD encompasses multiple injurious processes including inflammation (excessive or inappropriate innate and adaptive immunity), cellular apoptosis, altered cellular and molecular alveolar maintenance program, abnormal cell repair, extracellular matrix destruction (protease and anti-protease imbalance), and oxidative stress (oxidant and antioxidant imbalance). These processes are triggered by urban and rural air pollutants and active and/or passive cigarette smoke and modified by cellular senescence and infection. A series of receptor-mediated signal transduction pathways are activated by reactive oxygen species and tobacco components, resulting in impairment of a variety of cell signaling and cytokine networks, subsequently leading to chronic airway responses with mucus production, airway remodeling, and alveolar destruction. The authors provide an updated insight into the molecular and cellular pathobiology of COPD based on human and/or animal data.

Visual recognition memory and auditory brainstem response in infant rhesus monkeys exposed perinatally to environmental tobacco smoke

The impact of perinatal exposure to environmental tobacco smoke (ETS) on cognitive development is controversial. We exposed rhesus monkeys to ETS or filtered air (5 animals per group) beginning in utero on day 50 of pregnancy and continuing throughout postnatal testing. In infancy, we evaluated both groups for visual recognition memory and auditory function (auditory brainstem response). The ETS group showed significantly less novelty preference in the visual recognition task whereas no effects on auditory function were detected. These preliminary results support the view that perinatal ETS exposure has adverse effects on cognitive function and indicate further that rhesus monkeys may provide a valuable nonhuman primate model for investigating this link.