Proteomic alteration in lung tissue of rats exposed to cigarette smoke

Antiinflammation and Antioxidant Effects of Thalidomide on Pulmonary Fibrosis in Mice and Human Lung Fibroblasts

In this study, the potential effects of thalidomide (Thal) on bleomycin (BLM)-induced pulmonary fibrosis were investigated. BALB/C mice model of pulmonary fibrosis induced by an intratracheal instillation of BLM was adopted, and then was intraperitoneally injected with Thal (10, 20, 50 mg/kg) daily for 8 days, while the control and BLM-treated mouse groups were injected with a saline solution. The effects of Thal on pulmonary injury were evaluated by the lung wet/dry weight ratios and histopathological examination. Inflammation of lung tissues was assessed by measuring the levels of interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β in bronchoalveolar lavage fluid. Oxidative stress was evaluated by detecting the levels of reactive oxygen species (ROS), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and malondialdehyde (MDA) in lung tissue. The results indicated that Thal treatment remarkably attenuated pulmonary fibrosis, oxidative stress, and inflammation in mouse lungs. The antiinflammatory and antioxidant effects of Thal were also found in human lung fibroblasts. Thal administration significantly enhanced the activity of thioredoxin reductase; however, the other enzymes or proteins involved in biologic oxidation-reduction equilibrium were not affected. Our findings indicate that Thal-mediated suppression of pulmonary fibrosis is related to the inhibition of oxidative stress and inflammatory response. In summary, these results may provide a rationale to explore clinical application of Thal for the prevention of pulmonary fibrosis.

Chronic exposure to cigarette smoke leads to activation of p21 (RAC1)-activated kinase 6 (PAK6) in non-small cell lung cancer cells

Epidemiological data clearly establishes cigarette smoking as one of the major cause for lung cancer worldwide. Recently, targeted therapy has become one of the most preferred modes of treatment for cancer. Though certain targeted therapies such as anti-EGFR are in clinical practice, they have shown limited success in lung cancer patients who are smokers. This demands discovery of alternative drug targets through systematic investigation of cigarette smoke-induced signaling mechanisms. To study the signaling events activated in response to cigarette smoke, we carried out SILAC-based phosphoproteomic analysis of H358 lung cancer cells chronically exposed to cigarette smoke. We identified 1,812 phosphosites, of which 278 phosphosites were hyperphosphorylated (≥ 3-fold) in H358 cells chronically exposed to cigarette smoke. Our data revealed hyperphosphorylation of S560 within the conserved kinase domain of PAK6. Activation of PAK6 is associated with various processes in cancer including metastasis. Mechanistic studies revealed that inhibition of PAK6 led to reduction in cell proliferation, migration and invasion of the cigarette smoke treated cells. Further, siRNA mediated silencing of PAK6 resulted in decreased invasive abilities in a panel of non-small cell lung cancer (NSCLC) cells. Consistently, mice bearing tumor xenograft showed reduced tumor growth upon treatment with PF-3758309 (group II PAK inhibitor). Immunohistochemical analysis revealed overexpression of PAK6 in 66.6% (52/78) of NSCLC cases in tissue microarrays. Taken together, our study indicates that PAK6 is a promising novel therapeutic target for NSCLC, especially in smokers.

Tandem mass tags labeled quantitative proteomics to study the effect of tobacco smoke exposure on the rat lung

BACKGROUND

The causal link between tobacco smoke exposure (TSE) and numerous severe respiratory system diseases (RSD), including chronic bronchitis, chronic obstructive pulmonary disease, and lung cancer, is well established. However, the pathogenesis of TSE-induced RSD remains incompletely understood. This research aims to detect the pathogenetic mechanisms and potential therapeutic targets of TSE-induced RSD.

METHODS

This study employed TSE model which rats were exposed to a concentration of 60% tobacco smoke in a toxicant exposure system for four weeks. Tandem mass tags (TMT) labeled quantitative proteomics combined with off-line high pH reversed-phase fractionation, and nano-liquid chromatography-mass spectrometry method (off-line high pH RPF-nano-LC-MS/MS) were adopted to detect differentially expressed proteins (DEPs) in the lung tissues of the TSE model rats and to compare them with those in control. The accuracy of the results was verified by western blot.

RESULTS

Compared with the control group, 33 proteins in the TSE model group's lung tissues showed significant differential expression. Analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways indicated that, several biological pathways, such as the steroid biosynthesis pathway, were involved and played significant roles in the pathogenesis of the experimental group's TSE.

CONCLUSIONS

These findings make a crucial contribution to the search for a comprehensive understanding of TSE-induced RSD's pathogenesis, and furthermore provide guidance for the diagnosis and treatment of TSE-induced RSD.

E-Cigarette Use Causes a Unique Innate Immune Response in the Lung, Involving Increased Neutrophilic Activation and Altered Mucin Secretion

RATIONALE

E-cigarettes have become increasingly popular and little is known about their potential adverse health effects.

OBJECTIVES

To determine the effects of e-cigarette use on the airways.

METHODS

Induced sputum samples from cigarette smokers, e-cigarette users, and nonsmokers were analyzed by quantitative proteomics, and the total and individual concentrations of mucins MUC5AC and MUC5B were determined by light scattering/refractometry and labeled mass spectrometry, respectively. Neutrophil extracellular trap (NET) formation rates were also determined for the same groups.

MEASUREMENTS AND MAIN RESULTS

E-cigarette users exhibited significant increases in aldehyde-detoxification and oxidative stress-related proteins associated with cigarette smoke compared with nonsmokers. The levels of innate defense proteins associated with chronic obstructive pulmonary disease, such as elastase and matrix metalloproteinase-9, were significantly elevated in e-cigarette users as well. E-cigarette users' sputum also uniquely exhibited significant increases in neutrophil granulocyte-related and NET-related proteins, such as myeloperoxidase, azurocidin, and protein-arginine deiminase 4, despite no significant elevation in neutrophil cell counts. Peripheral neutrophils from e-cigarette users showed increased susceptibility to phorbol 12-myristate 13-acetate-induced NETosis. Finally, a compositional change in the gel-forming building blocks of airway mucus (i.e., an elevated concentration of mucin MUC5AC) was observed in both cigarette smokers and e-cigarette users.

CONCLUSIONS

Together, our results indicate that e-cigarette use alters the profile of innate defense proteins in airway secretions, inducing similar and unique changes relative to cigarette smoking. These data challenge the concept that e-cigarettes are a healthier alternative to cigarettes.

Cigarette smoke induced genotoxicity and respiratory tract pathology: evidence to support reduced exposure time and animal numbers in tobacco product testing

Many laboratories are working to develop in vitro models that will replace in vivo tests, but occasionally there remains a regulatory expectation of some in vivo testing. Historically, cigarettes have been tested in vivo for 90 days. Recently, methods to reduce and refine animal use have been explored. This study investigated the potential of reducing animal cigarette smoke (CS) exposure to 3 or 6 weeks, and the feasibility of separate lung lobes for histopathology or the Comet assay. Rats were exposed to sham air or CS (1 or 2 h) for 3 or 6 weeks. Respiratory tissues were processed for histopathological evaluation, and Alveolar type II cells (AEC II) isolated for the Comet assay. Blood was collected for Pig-a and micronucleus quantification. Histopathological analyses demonstrated exposure effects, which were generally dependent on CS dose (1 or 2 h, 5 days/week). Comet analysis identified that DNA damage increased in AEC II following 3 or 6 weeks CS exposure, and the level at 6 weeks was higher than 3 weeks. Pig-a mutation or micronucleus levels were not increased. In conclusion, this study showed that 3 weeks of CS exposure was sufficient to observe respiratory tract pathology and DNA damage in isolated AEC II. Differences between the 3 and 6 week data imply that DNA damage in the lung is cumulative. Reducing exposure time, plus analyzing separate lung lobes for DNA damage or histopathology, supports a strategy to reduce and refine animal use in tobacco product testing and is aligned to the 3Rs (replacement, reduction and refinement).

Role of thioredoxin nitration in bleomycin-induced pulmonary fibrosis in rats

Oxidant stimulation has been suggested to play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Our study aimed to investigate the role and mechanisms of thioredoxin (Trx) nitration during the development of IPF. A rat model of IPF was established by intratracheal instillation of bleomycin (BLM). Male Wistar rats were randomly distributed among the control group and BLM-treated group, in which rats were intratracheally instilled with a single dose of BLM (5.0 mg/kg body mass in 1.0 mL phosphate-buffered saline). At 7 or 28 days after instillation the rats were euthanized. Histopathological and biochemical examinations were performed. The activity and protein level of thioredoxin were assessed. The thioredoxin nitration level was determined using immunoprecipitation and immunoblotting techniques. Our results demonstrated that protein tyrosine nitration increased in the BLM-treated group compared with the control group. Trx activity decreased in the BLM group compared with control group, whereas Trx expression and nitration level increased dramatically in the BLM group compared with the control group. Our results indicated that Trx nitration might be involved in the pathogenesis of IPF.

Conditionally induced RAGE expression by proximal airway epithelial cells in transgenic mice causes lung inflammation

Background

Receptors for advanced glycation end-products (RAGE) are multiligand cell-surface receptors expressed abundantly by distal pulmonary epithelium. Our lab has discovered RAGE-mediated effects in the orchestration of lung inflammation induced by tobacco smoke and environmental pollutants; however, the specific contribution of RAGE to the progression of proximal airway inflammation is still inadequately characterized.

Methods and results

We generated a Tet-inducible transgenic mouse that conditionally overexpressed RAGE using the club cell (Clara) secretory protein (CCSP) promoter expressed by club (Clara) cells localized to the proximal airway. RAGE was induced for 40 days from weaning (20 days of age) until sacrifice date at 60 days. Immunohistochemistry, immunoblotting, and qPCR revealed significant RAGE up-regulation when compared to non-transgenic controls; however, H&E staining revealed no detectible morphological abnormalities and apoptosis was not enhanced during the 40 days of augmentation. Freshly procured bronchoalveolar lavage fluid (BALF) from CCSP-RAGE TG mice had significantly more total leukocytes and PMNs compared to age-matched control littermates. Furthermore, CCSP-RAGE TG mice expressed significantly more tumor necrosis factor alpha (TNF-α), interleukin 7 (IL-7), and interleukin 14 (IL-14) in whole lung homogenates compared to controls.

Conclusions

These data support the concept that RAGE up-regulation specifically in lung airways may function in the progression of proximal airway inflammation.

Identification of nuclear phosphoproteins as novel tobacco markers in mouse lung tissue following short-term exposure to tobacco smoke

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We analyzed nuclear phosphoprotein expression activated by tobacco smoke exposure.

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253 phosphoproteins were identified in 1-day and 7-day exposure groups.

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Of these, 33 were significantly differentially expressed in control and exposed groups.

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Identified proteins were related to inflammation, response to stress and nicotine.

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OSF3 and spectrin β chain were identified as candidate tobacco smoke markers.

Smoking is a risk factor for lung diseases, including chronic obstructive pulmonary disease and lung cancer. However, the molecular mechanisms mediating the progression of these diseases remain unclear. Therefore, we sought to identify signaling pathways activated by tobacco-smoke exposure, by analyzing nuclear phosphoprotein expression using phosphoproteomic analysis of lung tissue from mice exposed to tobacco smoke. Sixteen mice were exposed to tobacco smoke for 1 or 7 days, and the expression of phosphorylated peptides was analyzed by mass spectrometry. A total of 253 phosphoproteins were identified, including FACT complex subunit SPT16 in the 1-day exposure group, keratin type 1 cytoskeletal 18 (K18), and adipocyte fatty acid-binding protein, in the 7-day exposure group, and peroxiredoxin-1 (OSF3) and spectrin β chain brain 1 (SPTBN1), in both groups. Semi-quantitative analysis of the identified phosphoproteins revealed that 33 proteins were significantly differentially expressed between the control and exposed groups. The identified phosphoproteins were classified according to their biological functions. We found that the identified proteins were related to inflammation, regeneration, repair, proliferation, differentiation, morphogenesis, and response to stress and nicotine. In conclusion, we identified proteins, including OSF3 and SPTBN1, as candidate tobacco smoke-exposure markers; our results provide insights into the mechanisms of tobacco smoke-induced diseases.

Pathophysiology of tobacco smoke exposure: recent insights from comparative and redox proteomics

First-hand and second-hand tobacco smoke are causally linked to a huge number of deaths and are responsible for a broad spectrum of pathologies such as cancer, cardiovascular, respiratory, and eye diseases as well as adverse effects on female reproductive function. Cigarette smoke is a complex mixture of thousands of different chemical species, which exert their negative effects on macromolecules and biochemical pathways, both directly and indirectly. Many compounds can act as oxidants, pro-inflammatory agents, carcinogens, or a combination of these. The redox behavior of cigarette smoke has many implications for smoke related diseases. Reactive oxygen and nitrogen species (both radicals and non-radicals), reactive carbonyl compounds, and other species may induce oxidative damage in almost all the biological macromolecules, compromising their structure and/or function. Different quantitative and redox proteomic approaches have been applied in vitro and in vivo to evaluate, respectively, changes in protein expression and specific oxidative protein modifications induced by exposure to cigarette smoke and are overviewed in this review. Many gel-based and gel-free proteomic techniques have already been used successfully to obtain clues about smoke effects on different proteins in cell cultures, animal models, and humans. The further implementation with other sensitive screening techniques could be useful to integrate the comprehension of cigarette smoke effects on human health. In particular, the redox proteomic approach may also help identify biomarkers of exposure to tobacco smoke useful for preventing these effects or potentially predictive of the onset and/or progression of smoking-induced diseases as well as potential targets for therapeutic strategies.

Overexpression of RAGE contributes to cigarette smoke-induced nitric oxide generation in COPD

BACKGROUND

Receptor for advanced glycation end products (RAGE), a multiple-ligands receptor, is implicated in chronic obstructive pulmonary disease (COPD). This study was designed to investigate the potential role of RAGE in nitric oxide (NO) generation, an endogenous marker of nitrosative stress in COPD.

METHODS

Lung tissues from COPD patients were used to describe the relationship between RAGE expression and NO level. RAGE expression was assessed by immunohistochemistry, western blot, and ELISA. Human bronchial epithelial cells (16HBE) were cultured with cigarette smoke extract (CSE). Neutralizing antibody against RAGE was used to detect the role of RAGE in CSE-induced NO generation by 16HBE cells.

RESULTS

Compared with nonsmoker controls, overexpression of RAGE was significantly detected in COPD smokers (p < 0.01), but not healthy smokers and nonsmokers with COPD, which was dominantly expressed at bronchiolar epithelia. Correlation analysis showed that RAGE in COPD smokers was positively related to NO level, smoking status, and lung function decline. In cultured 16HBE cells treated with CSE, soluble RAGE was reduced; however, full-length RAGE was enhanced significantly as the same trend as NO generation. Moreover, increased NO level and NO synthase activity, decreased total glutathione (a major cellular antioxidant), enhanced nuclear translocation of p65 (a key molecule of nuclear factor (NF)-κB) and release of NF-κB-dependent proinflammatory cytokines were all reversed by pretreatment of anti-RAGE antibody.

CONCLUSIONS

These findings suggest that overexpression of RAGE contributes to CS-induced NO generation in COPD with involvement in NF-κB activation.

Association of polymorphisms of the receptor for advanced glycation end products gene with COPD in the Chinese population

The receptor for advanced glycation end products (RAGE) is a cell surface molecule of the immunoglobulin superfamily that binds diverse endogenous ligands involved in the development of chronic diseases and inflammatory damage. A growing body of evidence has suggested that RAGE is involved in the development and progression of chronic obstructive pulmonary disease (COPD). The present study investigated the existence of an association among three polymorphisms (-374T/A, -429T/C, and G82S) of the RAGE gene with the risk of COPD in the Chinese population. The RAGE genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism in 216 patients with COPD and 239 age-matched healthy individuals. Our study demonstrated that the frequencies of the GS genotype and the S allele in the G82S mutation were significantly higher in COPD patients than in controls (odds ratios [OR]=1.70, 95% confidence interval [CI]: 1.15-2.50, p=0.0098 and OR=1.42, 95% CI: 1.06-1.91, p=0.023, respectively). Further stratification analysis by smoking status revealed that the presence of the GS genotype conferred a higher risk of developing COPD in current smokers (p=0.044). In contrast, mutations at -374T/A and -429T/C did not demonstrate any association with COPD, even after taking into account the patients' smoking history. Our study provides preliminary evidence that the G82S polymorphism in the RAGE gene is associated with an increased risk of COPD and that the GS genotype of the G82S variant is a risk factor for COPD in the Chinese population.

RAGE: a new frontier in chronic airways disease

Asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous inflammatory disorders of the respiratory tract characterized by airflow obstruction. It is now clear that the environmental factors that drive airway pathology in asthma and COPD, including allergens, viruses, ozone and cigarette smoke, activate innate immune receptors known as pattern-recognition receptors, either directly or indirectly by causing the release of endogenous ligands. Thus, there is now intense research activity focused around understanding the mechanisms by which pattern-recognition receptors sustain the airway inflammatory response, and how these mechanisms might be targeted therapeutically. One pattern-recognition receptor that has recently come to attention in chronic airways disease is the receptor for advanced glycation end products (RAGE). RAGE is a member of the immunoglobulin superfamily of cell surface receptors that recognizes pathogen- and host-derived endogenous ligands to initiate the immune response to tissue injury, infection and inflammation. Although the role of RAGE in lung physiology and pathophysiology is not well understood, recent genome-wide association studies have linked RAGE gene polymorphisms with airflow obstruction. In addition, accumulating data from animal and clinical investigations reveal increased expression of RAGE and its ligands, together with reduced expression of soluble RAGE, an endogenous inhibitor of RAGE signalling, in chronic airways disease. In this review, we discuss recent studies of the ligand-RAGE axis in asthma and COPD, highlight important areas for future research and discuss how this axis might potentially be harnessed for therapeutic benefit in these conditions.

Smoke-induced microRNA and related proteome alterations. Modulation by chemopreventive agents

Dysregulation of microRNAs (miRNAs) has important consequences on gene and protein expression since a single miRNA targets a number of genes simultaneously. This article provides a review of published data and ongoing studies regarding the effects of cigarette smoke (CS), either mainstream (MCS) or environmental (ECS), on the expression of miRNAs and related proteins. The results generated in mice, rats, and humans provided evidence that exposure to CS results in an intense dysregulation of miRNA expression in the respiratory tract, which is mainly oriented in the sense of downregulation. In parallel, there was an upregulation of proteins targeted by the downregulated miRNAs. These trends reflect an attempt to defend the respiratory tract by means of antioxidant mechanisms, detoxification of carcinogens, DNA repair, anti-inflammatory pathways, apoptosis, etc. However, a long-lasting exposure to CS causes irreversible miRNA alterations that activate carcinogenic mechanisms, such as modulation of oncogenes and oncosuppressor genes, cell proliferation, recruitment of undifferentiated stem cells, inflammation, inhibition of intercellular communications, angiogenesis, invasion, and metastasis. The miRNA alterations induced by CS in the lung of mice and rats are similar to those observed in the human respiratory tract. Since a number of miRNAs that are modulated by CS and/or chemopreventive agents are subjected to single nucleotide polymorphisms in humans, they can be evaluated according to toxicogenomic/pharmacogenomics approaches. A variety of cancer chemopreventive agents tested in our laboratory modulated both baseline and CS-related miRNA and proteome alterations, thus contributing to evaluate both safety and efficacy of dietary and pharmacological agents.

Role of thioredoxin in lung disease

Thioredoxin system is a ubiquitous thiol oxidoreductase system that regulates cellular reduction/oxidation (redox) status. It includes thioredoxin (Trx), thioredoxin reductase (TrxR), and NADPH. Trx plays an essential role in cell function by limiting oxidative stress directly via antioxidant effects and indirectly by proteins interaction with key signal transduction molecules. A variety of signaling molecules have been implicated in the cytoprotection conferred by Trx, such as autophagic proteins, p38 mitogen-activated protein kinase, nuclear factor-κB, phosphatidylinositol 3-kinase. Recent studies indicated that Trx may contribute to the pathogenesis of COPD, asthma and lung injury. Enhanced Trx expression or application of recombinant Trx afforded protection in preclinical models of pulmonary tissue injury, which suggested Trx may be used in future therapeutic applications. The focus of this review is on the significance of Trx in various pulmonary diseases, which as a potential therapeutic strategy to protect against oxidative stress and inflammation.

Methods in tobacco abuse: proteomic changes following second-hand smoke exposure

Smoking is one of the leading preventable causes of disease, disability, and death in the USA and leads to more than 400,000 preventable deaths per year. Nicotine is the major alkaloid present in tobacco smoke, and many of the negative effects of smoking are attributed to nicotine. Nicotine is not only the addictive component of tobacco smoke, but also highly associated with carcinogenesis and induces oxidative stress. Furthermore, the administration of nicotine via subcutaneous mini-osmotic pumps or by injection is an established method in preclinical studies for this area of research. Thus, preclinical research on the negative effects of tobacco smoke and tobacco addiction has focused primarily on the effects of nicotine. However, there are over 4,500 components found in tobacco smoke, many of which are highly toxic. Other components may also contribute to the addictive properties of tobacco smoke. Furthermore, the negative effects of tobacco smoke are not isolated to the smoker but can have negative effects to those exposed to the secondhand smoke (SHS) stream. SHS exposure is the third leading cause of preventable death. Approximately 38,000 deaths per year are attributed to SHS exposure in the USA. SHS exposure increases the risk of heart disease by approximately 30% and is associated with increased risk of stroke, cancer, type II diabetes, as well as pulmonary disease. Thus, methods of administering tobacco smoke in a controlled environment will further our understanding of tobacco addiction and the role tobacco smoke in other disease states. Moreover, combining smoke exposure with proteomics can lead to the discovery of biomarkers that can be potentially useful tools in screening, early diagnosis, prevention, and treatment of diseases caused by SHS.

Proteome analysis of bronchoalveolar lavage in pulmonary langerhans cell histiocytosis

Background

Pulmonary Langerhans-cell histiocytosis (PLCH) is a rare interstitial lung disease characterized by clusters of Langerhans cells, organized in granulomas, in the walls of distal bronchioles. It is a diffuse lung disease related to tobacco smoking but otherwise of unknown etiopathogenesis.

Methods

In this study we used a proteomic approach to analyze BAL protein composition of patients with PLCH and of healthy smoker and non-smoker controls to obtain insights into the pathogenetic mechanisms of the disease, to study the effect of cigarette smoking on susceptibility to PLCH and to identify potential new biomarkers.

Results

Two-dimensional electrophoresis and image analysis revealed proteins that were differently expressed (quantitatively and qualitatively) in the three groups of subjects. The proteins were identified by mass spectrometry and have various functions (antioxidant, proinflammatory, antiprotease) and origins (plasma, locally produced, etc.). Many, such as protease inhibitors (human serpin B3) and antioxidant proteins (glutathione peroxidase and thioredoxin) are already linked to PLCH pathogenesis, whereas other proteins have never been associated with the disease. Interestingly, numerous proteolytic fragments of plasma proteins (including kininogen-1 N fragments and haptoglobin) were also identified and suggest increased proteolytic activity in this inflammatory lung disease. Differences in protein expression were found between the three groups and confirmed by Principal Component Analysis (PCA).

Conclusion

Analysis of BAL proteomes of PLCH patients and of smoker and non-smoker controls also proved to be useful for researching the pathogenetic mechanisms and for identifying biomarkers of this rare diffuse lung disease.

Proteomics in asthma and COPD phenotypes and endotypes for biomarker discovery and improved understanding of disease entities

The application of proteomics to respiratory diseases, such as asthma and COPD, has been limited compared to other fields, like cancer. Both asthma and COPD are recognised to be multi-factorial and complex diseases, both consisting of clusters of multiple disease phenotypes. The complexity of these diseases combined with the inaccessibility and invasiveness of disease relevant samples have provided a hurdle to the progress of respiratory proteomics. Advances in proteomic instrumentation and methodology have led to the possibility to identify proteomes in much smaller quantities of biological material. This review focuses on the efforts in respiratory proteomics in relation to asthma and COPD, and the importance of identifying subgroups of disease entities to establish appropriate biomarkers, and to enhance the understanding of underlying mechanisms in each subgroup. Careful phenotype characterisation of patient subpopulations is required to make improvement in the field of heterogeneous diseases such as asthma and COPD, and the clusters of phenotypes are likely to encompass subgroups of disease with distinct molecular mechanisms; endotypes. The utilisation of modern advanced proteomics in endotypes of asthma and COPD will likely contribute to the increased understanding of disease mechanisms, establishment of biomarkers for these endotypes and improved patient care.

Proteomic analyses of lung lysates from short-term exposure of Fischer 344 rats to cigarette smoke

A short-term 5 day mainstream cigarette smoke exposure study was conducted in Fischer 344 rats to identify changes in lung proteins. Groups of 10 male and female rats at 5 weeks of age were assigned to one of four exposure groups. Animals received either nose-only filtered air (Air Control) or 75, 200, or 400 mg total particulate matter (TPM)/m(3) of diluted cigarette smoke. Exposures were conducted for 3 h per day, for 5 consecutive days. One lung per animal was frozen in liquid nitrogen and processed for proteomic analyses. Lung lysates from control verses treated animals were screened with 650 antibodies for changes in signaling protein levels and phosphorylation using antibody microarray technology, and then over 100 of the top protein hits were assessed by immunoblotting. The top smoke-altered proteins were further evaluated using reverse lysate microarrays. Major protein changes showed medium to strong bands on Western blots, depended on dose and gender, and included protein-serine kinases (Cot/Tpl2, ERK1/2, GSK3α/β, MEK6, PKCα/γ, RSK1), protein phosphatases (PP4/A'2, PP1Cβ), and other proteins (caspase 5, CRMP2, Hsc70, Hsp60, Rac1 and STAT2). The most pronounced changes occurred with 75 mg TPM/m(3) exposed females and 200 mg TPM/m(3) exposed males. Smoke-altered proteins regulate apoptosis, stress response, cell structure, and inflammation. Changes in identified proteins may serve as early indicators of lung damage.

Proteomics of buccal cavity mucus in female tilapia fish (Oreochromis spp.): a comparison between parental and non-parental fish

Mouthbrooding is an elaborate form of parental care displayed by many teleost species. While the direct benefits of mouthbrooding such as protection and transportation of offsprings are known, it is unclear if mouthbrooding offers additional benefits to embryos during incubation. In addition, mouthbrooding could incur negative costs on parental fish, due to limited feeding opportunities. Parental tilapia fish (Oreochromis spp.) display an elaborated form of parental care by incubating newly hatched embryos in oral buccal cavity until the complete adsorption of yolk sac. In order to understand the functional aspects of mouthbrooding, we undertake a proteomics approach to compare oral mucus sampled from mouthbrooders and non-mouthbrooders, respectively. Majority of the identified proteins have also been previously identified in other biological fluids or mucus-rich organs in different organisms. We also showed the upregulation of 22 proteins and down regulation of 3 proteins in mucus collected from mouthbrooders. Anterior gradient protein, hemoglobin beta-A chain and alpha-2 globin levels were lower in mouthbrooder samples. Mouthbrooder oral mucus collectively showed increase levels of proteins related to cytoskeletal properties, glycolytic pathway and mediation of oxidative stress. Overall the findings suggest cellular stress response, probably to support production of mucus during mouthbrooding phase.

A further review of inhalation studies with cigarette smoke and lung cancer in experimental animals, including transgenic mice

CONTEXT

The lack of an effective animal model for pulmonary carcinogenesis in smokers is a continuing problem for researchers trying to design Potentially Reduced Risk Products for those smokers who are either unwilling or unable to quit smoking. The major failing of inhalation assays with cigarette smoke in laboratory animals is that these assays produce only small percentages of animals with pulmonary tumors (e.g. adenomas, with the occasional adenocarcinoma), as opposed to the highly invasive carcinomas (e.g. small cell and squamous cell) seen in smokers.

OBJECTIVE

To update previous reviews on animal models, and to add different types of transgenic (Tg) mice to the review.

METHODS

Reviews were made of articles retrieved from PubMed and elsewhere.

RESULTS

The addition of Tg mice to the arsenal of tests used for the evaluation of the carcinogenic potential of cigarettes did not result in any better understanding of the inability of such testing to reflect the epidemiological evidence for lung cancer in smokers.

CONCLUSION

As in previous reviews on the subject, the best assay providing support for the epidemiology data is still the 5-month whole-body exposure of male A/J mice to a combination of mainstream/sidestream smoke, followed by a 4-month recovery.

The receptor for advanced glycation end products (RAGE) and the lung

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin superfamily of cell surface molecules. As a pattern-recognition receptor capable of binding a diverse range of ligands, it is typically expressed at low levels under normal physiological conditions in the majority of tissues. In contrast, the lung exhibits high basal level expression of RAGE localised primarily in alveolar type I (ATI) cells, suggesting a potentially important role for the receptor in maintaining lung homeostasis. Indeed, disruption of RAGE levels has been implicated in the pathogenesis of a variety of pulmonary disorders including cancer and fibrosis. Furthermore, its soluble isoforms, sRAGE, which act as decoy receptors, have been shown to be a useful marker of ATI cell injury. Whilst RAGE undoubtedly plays an important role in the biology of the lung, it remains unclear as to the exact nature of this contribution under both physiological and pathological conditions.

Up-regulation of RAGE and S100A6 in rats exposed to cigarette smoke

Cigarette smoke has been widely investigated in terms of epidemiology and pathological endpoints in relation to human lung diseases and animal study. In this study we exposed Wistar rats to cigarette smoke at concentrations of 20% and 60% to explore potential molecular mechanisms at the protein level. Exposures were conducted twice a day, 5 days a week for 43 weeks. As a major metabolite of nicotine in cigarette, cotinine level in rat urine was determined by HPLC-MS. A dose-dependent analysis indicated that cotinine may be used as an exposure marker of cigarette smoke. Expression of receptor for advanced glycation endproducts (RAGE), an immunoglobulin super family that triggers the intracellular signal cascade reaction leading to inflammation and its ligand S100A6 (calgranulin) in bronchial epithelial cells and lung tissues of rats, were found to be positive correlated with cotinine levels, indicating that RAGE and S100A6 may be attributable to inflammation and oxidative damage caused by cigarette smoke.

Comparison of proteomic and transcriptomic profiles in the bronchial airway epithelium of current and never smokers

BACKGROUND

Although prior studies have demonstrated a smoking-induced field of molecular injury throughout the lung and airway, the impact of smoking on the airway epithelial proteome and its relationship to smoking-related changes in the airway transcriptome are unclear.

METHODOLOGY/PRINCIPAL FINDINGS

Airway epithelial cells were obtained from never (n = 5) and current (n = 5) smokers by brushing the mainstem bronchus. Proteins were separated by one dimensional polyacrylamide gel electrophoresis (1D-PAGE). After in-gel digestion, tryptic peptides were processed via liquid chromatography/ tandem mass spectrometry (LC-MS/MS) and proteins identified. RNA from the same samples was hybridized to HG-U133A microarrays. Protein detection was compared to RNA expression in the current study and a previously published airway dataset. The functional properties of many of the 197 proteins detected in a majority of never smokers were similar to those observed in the never smoker airway transcriptome. LC-MS/MS identified 23 proteins that differed between never and current smokers. Western blotting confirmed the smoking-related changes of PLUNC, P4HB1, and uteroglobin protein levels. Many of the proteins differentially detected between never and current smokers were also altered at the level of gene expression in this cohort and the prior airway transcriptome study. There was a strong association between protein detection and expression of its corresponding transcript within the same sample, with 86% of the proteins detected by LC-MS/MS having a detectable corresponding probeset by microarray in the same sample. Forty-one proteins identified by LC-MS/MS lacked detectable expression of a corresponding transcript and were detected in

CONCLUSIONS/SIGNIFICANCE

1D-PAGE coupled with LC-MS/MS effectively profiled the airway epithelium proteome and identified proteins expressed at different levels as a result of cigarette smoke exposure. While there was a strong correlation between protein and transcript detection within the same sample, we also identified proteins whose corresponding transcripts were not detected by microarray. This noninvasive approach to proteomic profiling of airway epithelium may provide additional insights into the field of injury induced by tobacco exposure.

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MESH Headings

• Adult
• Blotting, Western
• Bronchi/cytology
• Bronchi/drug effects
• Bronchi/metabolism
• Chromatography, Liquid/methods
• Electrophoresis, Polyacrylamide Gel/methods
• Epithelial Cells/cytology
• Epithelial Cells/drug effects
• Epithelial Cells/physiology
• Female
• Gene Expression Profiling
• Glycoproteins/metabolism
• Humans
• Male
• Microarray Analysis
• Middle Aged
• Molecular Sequence Data
• Phosphoproteins/metabolism
• Procollagen-Proline Dioxygenase/metabolism
• Protein Disulfide-Isomerases/metabolism
• Proteome/analysis
• Respiratory Mucosa/cytology
• Respiratory Mucosa/drug effects
• Smoking/adverse effects
• Tandem Mass Spectrometry/methods
• Uteroglobin/metabolism
• Young Adult
• Tobacco Products

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Grants

• R01 CA124640 NCI NIH HHS
• U01 ES016035 NIEHS NIH HHS
• R01CA124640 NCI NIH HHS
• U01ES016035 NIEHS NIH HHS

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Affiliation(s)

Katrina Steiling The Pulmonary Center, Boston University Medical Center, Boston, Massachusetts, United States of America.
Aran Y Kadar
Agnes Bergerat
James Flanigon
Sriram Sridhar
Vishal Shah
Q Rushdy Ahmad
Jerome S Brody
Marc E Lenburg
Martin Steffen
Avrum Spira

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Proteomic analysis of lung tissue of rats exposed to cigarette smoke and radon

This study examined the protein expression in lung tissues of rats exposed to radon and cigarette smoke using a proteomic approach. Male Wistar rats were exposed daily to radon at a concentration of 100,000 Bq/m(3) for 16 h, and then exposed to 20% cigarette smoke for 1 h for a period of 75 d, with the radon cumulative dose reaching 200 WLM (working level months). Proteins from rat lung tissue were separated by two-dimensional gel electrophoresis (2-DE), stained with Coomassie blue, and analyzed with ImageMaster two-dimensional (2D) platinum software. Differentially expressed proteins were analyzed by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MALDI-time of flight [TOF] MS or MALDI TOF/TOF-MS). Twenty prominent proteins that were correlated with signal transduction, metabolism, heat shock and stress, and cytoskeleton construction were identified. Some of the differential expression proteins were verified by Western blot analysis and immunohistochemical staining, and the results were consistent with 2-DE analysis. The identified proteins and peptides might be potential diagnostic markers of lung impairment induced by radon and cigarette smoke exposure.