University of Groningen
Air pollution exposure of lung models
Cattani Pinto Cavalieri, Isabella
DOI:
10.33612/diss.172080794
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Publication date: 2021
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Cattani Pinto Cavalieri, I. (2021). Air pollution exposure of lung models: focus on inflammation, oxidative stress and cyclic AMP signaling. University of Groningen. https://doi.org/10.33612/diss.172080794
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Chapter 8
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Air pollution is a major public health concern and constitutes one of the main environmental risk factors for mortality associated with unwanted respiratory events (Chen and Kan 2008, Kelly and Fussell 2011, Atkinson, Kang et al. 2014, Li, Sun et al. 2016, DeVries, Kriebel et al. 2017). The respiratory system is primarily affected because of its direct and frequent exposure to air pollution, which has been associated with chronic obstructive pulmonary disease (COPD) and lung cancer (Mills, Donaldson et al. 2009, Marino, Caruso et al. 2015, Li, Sun et al. 2016, DeVries, Kriebel et al. 2017, Consonni, Carugno et al. 2018, Miller and Newby 2020). In many countries, air pollution exceeds the acceptable WHO air quality guideline levels and is related to economic development, industrial growth, urbanization, energy consumption and transport (WHO 2006). Due to a composition of particulate matter (PM) and gases, air pollution has been linked to toxic health events (Xu, Barregard et al. 2013, Carlsten, Blomberg et al. 2016, Zhang, Zhang et al. 2017, Vilcassim, Thurston et al. 2019). Diesel exhaust particles (DEP) contain highly toxic compounds such as metals and polycyclic aromatic hydrocarbons, and are among the main components of air pollution (Wichmann 2007, EPA 2010, Steiner, Bisig et al. 2016). In order to reduce the impact of air pollutants released by diesel burning, the use of biodiesel has been considered as an alternative (Schmidt 2007, Christian Rodriguez Coronado 2009). In this thesis, we evaluated the effects of air pollution PM on lung (patho)physiology using both in vitro and in vivo approaches. DEP was obtained from the National Institute of Standards and Technology (NIST); this is a widely used compound for the assessment of the effects of DEP on a variety of lung disease-associated parameters (Nemmar, Subramaniyan et al. 2012, Nemmar, Al-Salam et al. 2018, Kim, Song et al. 2019). Of note, since this is a standardized form of DEP, it may not reflect the same composition as DEP from the current fleet in developed countries to which people are exposed. In addition, we compared the effects of DEP to diesel-biodiesel particulate matter (DBPM; obtained from fuel burning by public busses in Rio de Janeiro City).
Substantial evidence indicates that air pollution promotes the induction of inflammation and oxidative stress in the lungs (Larcombe, Phan et al. 2014, Nemmar, Al-Salam et al. 2015, Zuo, Cattani-Cavalieri et al. 2019, Cattani-Cavalieri, Valenca et al. 2020). On the other hand, signaling associated with (an increase in) the intracellular second messenger cAMP is known to reduce airway inflammation, oxidative stress and mitochondrial dysfunction (Zuo, Cattani-Cavalieri et al. 2019). The overall objective of the studies described in this thesis was to investigate and elucidate air pollution-induced mechanisms of airway inflammation and oxidative stress and assess their impact on cAMP signaling and mitochondrial function. To this aim, we studied the effects of
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exposure to well-known air pollution constituents (i.e., DBPM and DEP) using several in vitro and in vivo models.
The impact of air pollution particulate matter on oxidative stress in the airways Oxidative stress has been shown to play a central role in the mechanisms underlying unwanted effects of air pollution on the respiratory system (Auten and Davis 2009, Vattanasit, Navasumrit et al. 2014). As indicated, the airways are the primary part of the lungs affected by air pollution exposure. In Chapter 5, we reported that acute exposure of C57BL/6 mice to 250 and 1000 μg DBPM by intranasal instillation enhanced reactive oxygen species (ROS) secretion into the bronchoalveolar lavage (BAL) fluid. Overproduction of ROS has the ability to promote oxidative damage (Ray, Huang et al. 2012). Accordingly, we demonstrated that lungs from mice exposed to DBPM showed increased levels of the oxidative stress marker malondialdehyde. In line with our results, in vitro studies on human lung carcinoma epithelial cells (A549) and alveolar murine macrophages (RAW 264.7) exposed to ultrafine petrol exhaust particles revealed increased lipid peroxidation in these cells as indicated by augmented malondialdehyde levels as a read-out (Durga, Nathiya et al. 2014). In Chapter 7, we showed that DMF treatment diminished the elevation of intracellular total ROS, nitric oxide (NO) and peroxynitrite (OONO) in BAL of C57BL/6 mice exposed to DEP for 60 days (Fig. 1). Thus, air pollutants clearly induce oxidative stress, a process sensitive to pharmacological intervention with DMF.
In accordance with our findings, elevation of intracellular ROS detected using 2’, 7’-dichlorofluorescin diacetate (DCFDA) after repeated exposure of mice to PM extract has been reported (Pardo, Porat et al. 2016). The antioxidant system is able to prevent or reduce the effects of oxidative stress (Ray, Huang et al. 2012, Ighodaro and Akinloye 2018). The nuclear factor erythroid-derived-like 2 (Nrf2) pathway is activated in response to stress signals and is crucial in the defense against oxidative stress by promoting the induction and release of distinct cytoprotective enzymes. In Chapter 5, we evaluated the effects of different concentrations of DBPM on the Nrf2 signaling pathway in mouse lungs using an acute exposure model. We showed that the lower dose of DBPM was able to promote the upregulation of Nrf2 and heme oxygenase 1 (HO-1) protein expression without affecting protein levels of other antioxidants. Interestingly, the higher dose of DBPM did not induce Nrf2. Interestingly, the higher DBPM dose did no induce Nrf2 but did trigger a robust increase in ROS. Our data implicate that the higher dose of DBPM caused a more intense lung response probably leading to the activation of other
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antioxidant pathways (Chapter 5). Moreover, exposure of human bronchial epithelial cells (BEAS-2B) to DEP upregulated gene expression of HO-1, thioredoxin and superoxide dismutase 2 (SOD-2) (Chapter 6). Chronic exposure (60 days) of mice to DEP showed no changes in Nrf2. However, the protein levels of glutathione peroxidase-1/2 (Gpx-peroxidase-1/2) and catalase (CAT) were increased in defense against DEP-induced oxidative stress, which could be reduced by DMF treatment (Chapter 7). This was an interesting observation as it was anticipated that DMF promotes the expression of Gpx-1/2 and CAT (representing part of the antioxidant response) to reduce the effects of DEP exposure. Conversely, it can be postulated that because of simultaneous treatment with DMF, the antioxidant response was not as profound at the time of marker assessment since (further) DEP-induced stress (and therefore the antioxidant response) was already prevented by DMF. In A549 cells, 30–60 min exposure to PM2.5 induced nuclear
translocation of Nrf2 (Deng, Rui et al. 2013). Differences in Nrf2 induction/activation between whole lung and A549 cells might be explained by the fact that A549 cells are an alveolar epithelial cell line derived from lung carcinomatous tissue and/or by the difference in exposure time to the irritant (30-60 min vs 60 days). Glutathione (GSH) plays a central role in cellular redox balance (van der Toorn, Smit-de Vries et al. 2007) and while GSH deficiency leads to an increased susceptibility to oxidative stress (implicated in the progression of cancer), elevated GSH levels may increase the antioxidant capacity and subsequent resistance to oxidative stress as reported in several cancer cells (Traverso, Ricciarelli et al. 2013). Thus, it is rather likely that the cellular responses induced upon exposure to air pollutant particles differ based on the model and type of cell studied. Additionally, the exposure time to the irritant and the timepoint(s) when the markers of interest are assessed may importantly impact the observed cellular responses as well. We found different outcomes on Nrf2 in our studies with DEP and DBPM in acute and chronic models, and demonstrated the ability of air pollution particles to induce several cellular signaling pathways, including those involving Nrf2, HO-1, Gpx-1/2 and CAT, in response to oxidative stress in the lungs. Moreover, we showed that acute and chronic exposure to DBPM and DEP, respectively, differentially affected Nrf2 expression, suggesting that Nrf2 may rely on the time of exposure and/or stimulant used. Our findings could reflect newly identified dynamics of Nrf2 expression and function in acute and chronic stress.
The effects of exposure to air pollution particulate matter on airway inflammation Airway inflammation is closely linked to the detrimental effects of air pollution on respiratory health. Because of their ability to release cytokines, inflammatory cells (e.g.,
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neutrophils and macrophages) are crucial for this process in the lung (Kelly and Fussell 2011, Ristovski, Miljevic et al. 2012). Importantly, air pollution exposure has been associated with severe acute exacerbations of COPD and asthma (Faustini, Stafoggia et al. 2013, Choi, Oh et al. 2018, Pothirat, Chaiwong et al. 2019). In Chapters 5 and 7, we showed that acute exposure of mice to DBPM and DEP elevated the number of macrophages in the alveolar parenchyma (Fig. 1). Additionally, chronic exposure to DEP resulted in an increase in total inflammatory cells in BAL, which could be effectively reduced by DMF treatment (Chapter 7) (Fig. 1). Our findings are in agreement with previous reports demonstrating that chronic exposure to DEP increased the number of macrophages and total inflammatory cells in BAL in mice (Nemmar, Subramaniyan et al. 2012, Kim, Song et al. 2019), and elevated macrophages in lung tissue from mice and rats (Santana, Pinheiro et al. 2019, Wang, Li et al. 2019). Thus, our findings indicate that acute and chronic exposure to air pollution PM are sufficient to induce an elevation of inflammatory cells both in BAL and lung tissue (Fig. 1). NF-κB is an inducible transcription factor which is crucial in the regulation of inflammation by driving the transcription and subsequent release of several cytokines, chemokines and growth factors after its activation (Liu, Zhang et al. 2017). We demonstrated an increase in p-NF-κB and p-NF-κB p65 in whole lung tissue homogenates after DBPM and DEP exposure, respectively (Chapter 5 and 7). The ability of DMF to inhibit DEP-induced inflammation was confirmed by reduced protein levels of NF-κB p65 after DMF treatment in whole lung tissue homogenates of DEP-exposed mice (Chapter 7) (Fig. 1). Further, in Chapter 5 and 6 we assessed the effects of DBPM and DEP on the induction of cytokines in mice and BEAS-2B cells, respectively. DBPM exposure elevated tumor necrosis factor-α (TNF-α) in BAL (Chapter 5), and BEAS-2B cells exposed to different concentrations of DEP demonstrated increased interleukin (IL)- 8 and IL-6 mRNA and protein levels (Chapter 6). Previous findings using a different model showed that exposure of mice to a higher dose (200 µg/ml) of DEP for 1 day induced IL-8, IL-6, and TNF-α protein expression in BAL and lung homogenates (Li, Liu et al. 2018). Additionally, an in vitro study showed that exposure of primary bronchial epithelial cells to aerosolized DEP increased gene expression of C-X-C motif chemokine ligand 8 (CXCL8), TNF-α, and NF-κB (Ji, Upadhyay et al. 2018). Collectively, these data indicate that exposure to air pollution, and more specifically DBPM and DEP, is a potent inducer of NF-κB signaling and, subsequently, the associated increase in specific cytokines and chemokines.
Overall, even though DBPM and DEP sufficiently induce airway inflammation and trigger cellular signaling associated with oxidative stress, some features are differentially
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affected by these air pollution constituents. To answer the question if DBPM is less harmful to lung health than DEP, based on read-outs such as inflammation and oxidative stress, future experimentation directly comparing the acute and chronic effects of DBPM and DEP (using the same model) is required. Future investigations will be designed towards this aim.
The impact of DEP exposure on epithelial to mesenchymal transition
Epithelial to mesenchymal transition (EMT) is a process characterized by a loss of epithelial cell integrity and barrier function concomitant with the transformation from an epithelial to a more mesenchymal cell phenotype (Thiery, Acloque et al. 2009, Wang, Wang et al. 2013, Jolly, Ward et al. 2018, Zuo, Cattani-Cavalieri et al. 2019). In Chapter 6, we investigated the effects of DEP on the expression of EMT markers. We demonstrated that exposure of BEAS-2B cells to DEP induced the mesenchymal markers TGF-β1, β-catenin and collagen-1, and reduced the expression of the epithelial markers E-cadherin and ZO-1. Thus far, only a limited number of other studies have investigated the impact of air pollution on the EMT process. A recent study showed that chronic exposure of BEAS-2B to a low concentration (2 g/ml, which is 50-150 times lower than that used in our studies) of DEP (SRM 1650b) for 6 months did not change the protein expression of E-cadherin, vimentin and N-cadherin, implying no effect on EMT (Savary, Bellamri et al. 2018). Surprisingly, no indices of (increased) inflammation, oxidative stress or genotoxicity were observed either in their hands (Savary, Bellamri et al. 2018). Compared to our work, these findings may indicate that the source and type of air pollutants may promote different degrees of EMT and lung damage. In addition, it needs to be noted that exposure time to and concentration of DEP appear to be critical to the cellular responses observed.
The effects of DEP exposure on cAMP signaling
Cyclic adenosine monophosphate (cAMP) is a versatile second messenger paramount to the propagation of extracellular signals into the cells, which is reflected by its regulation of numerous physiological processes (Valsecchi, Ramos-Espiritu et al. 2013, Raker, Becker et al. 2016). For example, cAMP signaling is involved in maintaining epithelial barrier function (Oldenburger, Maarsingh et al. 2012, Poppinga, Munoz-Llancao et al. 2014), which is considered to play a beneficial role in governing lung function (Oldenburger, Maarsingh et al. 2012). However, the direct impact of DEP exposure on cAMP signaling has not been reported to date (Fig. 1). The induction of cAMP is primarily
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initiated by Gs-protein-coupled receptors, such as the β2‐adrenoceptor (β2-AR) and distinct prostanoid E receptors (EP). In Chapter 2, we described how cAMP scaffolds may contribute to COPD symptoms and elaborated on their potential role under conditions of health and disease. In Chapter 6, we showed that DEP exposure induced changes in the expression of Epac1 without significantly changing the expression of Epac2 or phospho-PKA substrates. In contrast to these findings, our group previously demonstrated that Epac and PKA played a partial role (in a coordinated manner) in the regulation of inflammation, oxidative stress and EMT (Oldenburger, Maarsingh et al. 2012, Oldenburger, Roscioni et al. 2012, Oldenburger, Timens et al. 2014, Jansen, Poppinga et al. 2016). Thus, we demonstrated that Epac1 links β-catenin to EMT in A549 cells (Jansen, Poppinga et al. 2016). Moreover, using an acute animal model of cigarette smoke exposure, we revealed that Epac1 inhibited the process of remodeling linked to EMT, whereas Epac2 promoted inflammation (Oldenburger, Timens et al. 2014). In Chapter 6, we described that DEP exposure induced the gene expression of β2-AR and EP4 but not EP2 and EP3. Moreover, DEP augmented the mRNA expression of adenylate cyclase (AC) 7, AC3 and AC6, but did not affect AC1, AC4, and AC5 expression levels. In line with our findings, changes in the expression profile of cAMP generating receptors have been demonstrated in diseased lungs (Insel, Sriram et al. 2019, Haak, Ducharme et al. 2020). Furthermore, primary murine tracheal epithelial cells and human airway smooth muscle cells exposed to polycyclic aromatic hydrocarbons, which are released during diesel burning, exhibited reduced cAMP production upon β2-AR stimulation as well as a decrease in β2-β2-AR expression (Factor, Akhmedov et al. 2011). In Chapter 6, we used the GloSensor cAMP assay to evaluate real-time changes in cAMP levels in live BEAS-2B cells. We showed that DEP exposure (300 µg/ml) dramatically reduced cAMP production in response to forskolin (direct AC activator), fenoterol (β2-AR agonist), and a stable PGE2 analogue (EP4 agonist). Our findings indicate that DEP modifies the ability of cAMP generating receptors and ACs to increase cellular cAMP, which could have detrimental implications for proper lung function (Oldenburger, Maarsingh et al. 2012, Poppinga, Munoz-Llancao et al. 2014, Insel, Sriram et al. 2019). Our group has demonstrated previously that cAMP compartments associate the β2-AR with members of the AKAP family, a process linked to induction of EMT in TGF-β1/cigarette smoke-exposed BEAS-2B cells (Zuo, Trombetta-Lima et al. 2020). Data presented in Chapter 6 show that DEP was able to increase AKAP1 gene expression in BEAS-2B cells. AKAP1 has been associated with mitochondrial cAMP compartmentalization and function, acting as a mitochondrial scaffold protein (Hiura, Li et al. 2000, Zhao, Ma et al. 2009, Merrill and Strack 2014, Czachor, Failla et al. 2016). Taken together, our results indicate that DEP exposure results in an impaired cellular
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ability to produce cAMP (Fig. 1), which may be linked to altered expression profiles of key intermediates (e.g., receptors and/or specific anchoring proteins) and a disrupted communication between AC activation and cAMP production. Functionally, these changes appear to promote EMT and (further) contribute to lung injury.
The impact of DEP on mitochondrial function
In mitochondria, the promotion of oxidative stress and inflammation may occur through elevated levels of reactive oxygen species (ROS), which leads to mitochondrial dysfunction (Ray, Huang et al. 2012, De Giusti, Caldiz et al. 2013, Schieber and Chandel 2014). In Chapter 6, we showed that DEP exposure induced mRNA expression of the mitochondrial matrix enzyme SOD-2 (Ighodaro and Akinloye 2018), implicating an alteration in mitochondrial function. In addition, we investigated whether exposure to DEP affected mitochondrial morphology. For this purpose, mitochondria were grouped in three different categories: category I, elongated mitochondria; category II, fragmented mitochondria; and category III, mitochondria with undecided morphology. We found that DEP induced fragmentation of mitochondria (switch from category I to II) (Fig. 1), which is indicative of mitochondrial dysfunction (Dolga, Netter et al. 2013). Under certain conditions such as stress, cells require additional cellular energy which can be produced by oxidative phosphorylation; the ‘extra’ amount of ATP that can be generated is referred to as the mitochondrial spare capacity (Dolga, Netter et al. 2013). It is important to note the crucial role of ATP production for energy metabolism in cells. ATP-linked respiration is a measure for the efficiency of energy transduction of mitochondria (Hill, Benavides et al. 2012). In Chapter 6, we demonstrated that DEP exposure significantly reduced basal respiration, ATP-linked respiration, and mitochondrial spare capacity (Fig. 1), indicating profound effects of DEP on energy metabolism. Glycolysis is an important pathway used by the cells for energy production. We demonstrated that exposure of BEAS-2B cells to DEP reduced glycolytic capacity and reserve. These results reveal that the cellular ability to produce additional energy under conditions of DEP exposure is markedly reduced. Reductions in mitochondrial membrane potential of murine alveolar macrophages (exposed to DEP) (Zhao, Ma et al. 2009) and RAW 264.7 macrophages (exposed to DEP extract from a light-duty diesel source) (Hiura, Li et al. 2000) have been reported. These studies further demonstrate the ability of DEP to promote mitochondrial dysfunction. Our findings described in Chapter 6 clearly indicate that DEP exposure is able to concentration-dependently induce modifications in mitochondrial morphology and bioenergetics. Such disturbances in cellular mitochondrial function may potentially
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contribute to lung dysfunction including induction of EMT and inflammation. Our studies are the first to address the effects of DEP exposure on specific aspects of mitochondrial function, including mitochondrial respiration, spare capacity, and glycolytic reserve, in human bronchial epithelial cells.
Figure 1. The impact of diesel-biodiesel particulate matter (DBPM) and diesel exhaust particles
(DEP) on parameters of lung injury and function in mice and human bronchial epithelial cells. DBPM induced inflammation and oxidative stress, which was associated with an increase in p-NF-κB and Nrf2 protein expression in the lungs. Similarly, exposure of mice to DEP resulted in inflammation, oxidative stress, and the promotion of lung injury. Dimethyl fumarate (DMF) treatment effectively reduced lung injury, inflammation, and oxidative stress after DEP exposure in mice. In vitro studies using human bronchial epithelial cells revealed that DEP promoted mitochondrial dysfunction, induced epithelial to mesenchymal transition (EMT), and impaired the cellular ability to produce cAMP.
Future perspective
The studies described in this thesis show that exposure to air pollutants — and more specifically DEP and DB particulate matter — promotes airway inflammation, oxidative stress and EMT. Furthermore, exposure to DEP induced mitochondrial dysfunction and changes in the cellular ability to produce cAMP. We speculate that mitochondrial cAMP
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nanodomains play a critical role in the disruption of cAMP homeostasis. Further studies are warranted to better understand the molecular mechanisms that drive the detrimental effects of various kinds of air pollution PM on lung health.
Oxidative stress and inflammation collectively promote lung damage and represent the main underlying mechanisms of air pollution toxicity. Clearly, there is an urgent need to identify therapeutic strategies that target these processes. To the best of our knowledge, only a few studies have investigated potential drugs or substances that may prevent or reduce the effects (e.g. inflammation and oxidative stress) caused by air pollution in the lungs (Zin, Silva et al. 2012, Nemmar, Al-Salam et al. 2015, Nemmar, Al-Salam et al. 2018). Our studies identify and highlight the therapeutic potential of DMF to reduce DEP-induced parameters of airway inflammation, oxidative/nitrosative stress, and overall lung injury. The exact mechanisms by which DMF affects the inflammatory response and antioxidant system will be the topic of future research by our group.
Main conclusions
Taken together, the following conclusions can be derived from the studies described in this thesis:
• Acute exposure to DBPM triggers an inflammatory response characterized by an increase in the number of macrophages and TNF- protein expression in the lungs of mice. Moreover, it promotes oxidative damage by increasing the expression of ROS and lipid peroxidation as indicated by elevated malondialdehyde levels (Chapter 5).
• The inflammatory response and oxidative damage induced by exposure to DBPM may be related to increased protein expression of p-NF-κB and Nrf2 in the lung parenchyma (Chapter 5).
• DEP exposure induces oxidative stress, inflammatory cytokine expression and markers of EMT in BEAS-2B cells (Chapter 6).
• DEP exposure results in cellular changes that lead to an impaired ability of Gs-protein-coupled receptors and members of the AC superfamily to generate cAMP. These changes occur concomitantly with the induction of several indices of mitochondrial dysfunction (Chapter 6). Both the reduced capacity to produce cAMP and the modifications in mitochondrial morphology and bioenergetics are likely to contribute to the detrimental effects of air pollution (particulate matter) on lung health.
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• DMF treatment effectively inhibits DEP-induced oxidative stress (reduction of intracellular total ROS) and nitrosative stress (decrease in OONO and NO) (Chapter 7). Airway inflammation induced by chronic DEP exposure appears to be associated with an increase in NF-kB p65 (and Keap-1), which can be reduced by DMF treatment as well (Chapter 7). Collectively, our data indicate that DMF could be considered a therapeutic agent for the treatment of inflammatory airway disorders associated with air pollution.
224 References
Atkinson, R. W., S. Kang, H. R. Anderson, I. C. Mills and H. A. Walton (2014). "Epidemiological time series studies of PM2.5 and daily mortality and hospital admissions: a systematic review and meta-analysis." Thorax 69(7): 660-665. Auten, R. L. and J. M. Davis (2009). "Oxygen toxicity and reactive oxygen species: the
devil is in the details." Pediatr Res 66(2): 121-127.
Carlsten, C., A. Blomberg, M. Pui, T. Sandstrom, S. W. Wong, N. Alexis and J. Hirota (2016). "Diesel exhaust augments allergen-induced lower airway inflammation in allergic individuals: a controlled human exposure study." Thorax 71(1): 35-44. Cattani-Cavalieri, I., S. D. S. Valenca and M. Schmidt (2020). "Nanodomains in
cardiopulmonary disorders and the impact of air pollution." Biochem Soc Trans. Chen, B. and H. Kan (2008). "Air pollution and population health: a global challenge."
Environ Health Prev Med 13(2): 94-101.
Choi, J., J. Y. Oh, Y. S. Lee, K. H. Min, G. Y. Hur, S. Y. Lee, K. H. Kang and J. J. Shim (2018). "Harmful impact of air pollution on severe acute exacerbation of chronic obstructive pulmonary disease: particulate matter is hazardous." Int J Chron Obstruct Pulmon Dis 13: 1053-1059.
Christian Rodriguez Coronado, J. A. d. C., José Luz Silveira (2009). "Biodiesel CO2 emissions: A comparison with the main fuels in the Brazilian market." Fuel Processing Technology 90(2): 204-211.
Consonni, D., M. Carugno, S. De Matteis, F. Nordio, G. Randi, M. Bazzano, N. E. Caporaso, M. A. Tucker, P. A. Bertazzi, A. C. Pesatori, J. H. Lubin and M. T. Landi (2018). "Outdoor particulate matter (PM10) exposure and lung cancer risk in the EAGLE study." PLoS One 13(9): e0203539.
Czachor, A., A. Failla, R. Lockey and N. Kolliputi (2016). "Pivotal role of AKAP121 in mitochondrial physiology." Am J Physiol Cell Physiol 310(8): C625-628.
De Giusti, V. C., C. I. Caldiz, I. L. Ennis, N. G. Perez, H. E. Cingolani and E. A. Aiello (2013). "Mitochondrial reactive oxygen species (ROS) as signaling molecules of intracellular pathways triggered by the cardiac renin-angiotensin II-aldosterone system (RAAS)." Front Physiol 4: 126.
Deng, X., W. Rui, F. Zhang and W. Ding (2013). "PM2.5 induces Nrf2-mediated defense mechanisms against oxidative stress by activating PIK3/AKT signaling pathway in human lung alveolar epithelial A549 cells." Cell Biol Toxicol 29(3): 143-157. DeVries, R., D. Kriebel and S. Sama (2017). "Outdoor Air Pollution and COPD-Related
Emergency Department Visits, Hospital Admissions, and Mortality: A Meta-Analysis." COPD 14(1): 113-121.
Dolga, A. M., M. F. Netter, F. Perocchi, N. Doti, L. Meissner, S. Tobaben, J. Grohm, H. Zischka, N. Plesnila, N. Decher and C. Culmsee (2013). "Mitochondrial small conductance SK2 channels prevent glutamate-induced oxytosis and mitochondrial dysfunction." J Biol Chem 288(15): 10792-10804.
Durga, M., S. Nathiya, A. Rajasekar and T. Devasena (2014). "Effects of ultrafine petrol exhaust particles on cytotoxicity, oxidative stress generation, DNA damage and inflammation in human A549 lung cells and murine RAW 264.7 macrophages." Environ Toxicol Pharmacol 38(2): 518-530.
EPA (2010). Quantitative Health Risk Assessment for Particulate Matter. Particulate Matter (PM) Standards - Documents from Review Completed in 2012 - Risk and Exposure Assessments. G. McCarthy. Washington, United States Environmental Protection Agency: 1-596.
225
Factor, P., A. T. Akhmedov, J. D. McDonald, A. Qu, J. Wu, H. Jiang, T. Dasgupta, R. A. Panettieri, Jr., F. Perera and R. L. Miller (2011). "Polycyclic aromatic hydrocarbons impair function of beta2-adrenergic receptors in airway epithelial and smooth muscle cells." Am J Respir Cell Mol Biol 45(5): 1045-1049.
Faustini, A., M. Stafoggia, P. Colais, G. Berti, L. Bisanti, E. Cadum, A. Cernigliaro, S. Mallone, C. Scarnato, F. Forastiere and G. EpiAir Collaborative (2013). "Air pollution and multiple acute respiratory outcomes." Eur Respir J 42(2): 304-313. Haak, A. J., M. T. Ducharme, A. M. Diaz Espinosa and D. J. Tschumperlin (2020). "Targeting GPCR Signaling for Idiopathic Pulmonary Fibrosis Therapies." Trends Pharmacol Sci 41(3): 172-182.
Hill, B. G., G. A. Benavides, J. R. Lancaster, Jr., S. Ballinger, L. Dell'Italia, Z. Jianhua and V. M. Darley-Usmar (2012). "Integration of cellular bioenergetics with mitochondrial quality control and autophagy." Biol Chem 393(12): 1485-1512. Hiura, T. S., N. Li, R. Kaplan, M. Horwitz, J. C. Seagrave and A. E. Nel (2000). "The role
of a mitochondrial pathway in the induction of apoptosis by chemicals extracted from diesel exhaust particles." J Immunol 165(5): 2703-2711.
Ighodaro, O. M. and O. A. Akinloye (2018). "First line defence antioxidants-superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX): Their fundamental role in the entire antioxidant defence grid." Alexandria Journal of Medicine 54(4): 287-293.
Insel, P. A., K. Sriram, M. W. Gorr, S. Z. Wiley, A. Michkov, C. Salmeron and A. M. Chinn (2019). "GPCRomics: An Approach to Discover GPCR Drug Targets." Trends Pharmacol Sci 40(6): 378-387.
Jansen, S. R., W. J. Poppinga, W. de Jager, F. Lezoualc'h, X. Cheng, T. Wieland, S. J. Yarwood, R. Gosens and M. Schmidt (2016). "Epac1 links prostaglandin E2 to beta-catenin-dependent transcription during epithelial-to-mesenchymal transition." Oncotarget 7(29): 46354-46370.
Ji, J., S. Upadhyay, X. Xiong, M. Malmlof, T. Sandstrom, P. Gerde and L. Palmberg (2018). "Multi-cellular human bronchial models exposed to diesel exhaust particles: assessment of inflammation, oxidative stress and macrophage polarization." Part Fibre Toxicol 15(1): 19.
Jolly, M. K., C. Ward, M. S. Eapen, S. Myers, O. Hallgren, H. Levine and S. S. Sohal (2018). "Epithelial-mesenchymal transition, a spectrum of states: Role in lung development, homeostasis, and disease." Dev Dyn 247(3): 346-358.
Kelly, F. J. and J. C. Fussell (2011). "Air pollution and airway disease." Clin Exp Allergy 41(8): 1059-1071.
Kim, D. I., M. K. Song, S. H. Kim, C. Y. Park and K. Lee (2019). "TF-343 Alleviates Diesel Exhaust Particulate-Induced Lung Inflammation via Modulation of Nuclear Factor-kappaB Signaling." J Immunol Res 2019: 8315845.
Larcombe, A. N., J. A. Phan, A. Kicic, K. L. Perks, R. Mead-Hunter and B. J. Mullins (2014). "Route of exposure alters inflammation and lung function responses to diesel exhaust." Inhal Toxicol 26(7): 409-418.
Li, J., S. Sun, R. Tang, H. Qiu, Q. Huang, T. G. Mason and L. Tian (2016). "Major air pollutants and risk of COPD exacerbations: a systematic review and meta-analysis." Int J Chron Obstruct Pulmon Dis 11: 3079-3091.
Li, W., T. Liu, Y. Xiong, J. Lv, X. Cui and R. He (2018). "Diesel exhaust particle promotes tumor lung metastasis via the induction of BLT1-mediated neutrophilic lung inflammation." Cytokine 111: 530-540.
226
Liu, T., L. Zhang, D. Joo and S. C. Sun (2017). "NF-kappaB signaling in inflammation." Signal Transduct Target Ther 2.
Marino, E., M. Caruso, D. Campagna and R. Polosa (2015). "Impact of air quality on lung health: myth or reality?" Ther Adv Chronic Dis 6(5): 286-298.
Merrill, R. A. and S. Strack (2014). "Mitochondria: a kinase anchoring protein 1, a signaling platform for mitochondrial form and function." Int J Biochem Cell Biol 48: 92-96.
Miller, M. R. and D. E. Newby (2020). "Air pollution and cardiovascular disease: car sick." Cardiovasc Res 116(2): 279-294.
Mills, N. L., K. Donaldson, P. W. Hadoke, N. A. Boon, W. MacNee, F. R. Cassee, T. Sandstrom, A. Blomberg and D. E. Newby (2009). "Adverse cardiovascular effects of air pollution." Nat Clin Pract Cardiovasc Med 6(1): 36-44.
Nemmar, A., S. Al-Salam, S. Beegam, P. Yuvaraju, N. Hamadi and B. H. Ali (2018). "In Vivo Protective Effects of Nootkatone against Particles-Induced Lung Injury Caused by Diesel Exhaust Is Mediated via the NF-kappaB Pathway." Nutrients 10(3).
Nemmar, A., S. Al-Salam, P. Yuvaraju, S. Beegam and B. H. Ali (2015). "Emodin mitigates diesel exhaust particles-induced increase in airway resistance, inflammation and oxidative stress in mice." Respir Physiol Neurobiol 215: 51-57. Nemmar, A., D. Subramaniyan, S. Zia, J. Yasin and B. H. Ali (2012). "Airway resistance, inflammation and oxidative stress following exposure to diesel exhaust particle in angiotensin II-induced hypertension in mice." Toxicology 292(2-3): 162-168. Oldenburger, A., H. Maarsingh and M. Schmidt (2012). "Multiple facets of cAMP
signalling and physiological impact: cAMP compartmentalization in the lung." Pharmaceuticals (Basel) 5(12): 1291-1331.
Oldenburger, A., S. S. Roscioni, E. Jansen, M. H. Menzen, A. J. Halayko, W. Timens, H. Meurs, H. Maarsingh and M. Schmidt (2012). "Anti-inflammatory role of the cAMP effectors Epac and PKA: implications in chronic obstructive pulmonary disease." PLoS One 7(2): e31574.
Oldenburger, A., W. Timens, S. Bos, M. Smit, A. V. Smrcka, A. C. Laurent, J. Cao, M. Hylkema, H. Meurs, H. Maarsingh, F. Lezoualc'h and M. Schmidt (2014). "Epac1 and Epac2 are differentially involved in inflammatory and remodeling processes induced by cigarette smoke." FASEB J 28(11): 4617-4628.
Pardo, M., Z. Porat, A. Rudich, J. J. Schauer and Y. Rudich (2016). "Repeated exposures to roadside particulate matter extracts suppresses pulmonary defense mechanisms, resulting in lipid and protein oxidative damage." Environ Pollut 210: 227-237.
Poppinga, W. J., P. Munoz-Llancao, C. Gonzalez-Billault and M. Schmidt (2014). "A-kinase anchoring proteins: cAMP compartmentalization in neurodegenerative and obstructive pulmonary diseases." Br J Pharmacol 171(24): 5603-5623. Pothirat, C., W. Chaiwong, C. Liwsrisakun, C. Bumroongkit, A. Deesomchok, T.
Theerakittikul, A. Limsukon, P. Tajarernmuang and N. Phetsuk (2019). "Acute effects of air pollutants on daily mortality and hospitalizations due to cardiovascular and respiratory diseases." J Thorac Dis 11(7): 3070-3083. Raker, V. K., C. Becker and K. Steinbrink (2016). "The cAMP Pathway as Therapeutic
227
Ray, P. D., B. W. Huang and Y. Tsuji (2012). "Reactive oxygen species (ROS) homeostasis and redox regulation in cellular signaling." Cell Signal 24(5): 981-990.
Ristovski, Z. D., B. Miljevic, N. C. Surawski, L. Morawska, K. M. Fong, F. Goh and I. A. Yang (2012). "Respiratory health effects of diesel particulate matter." Respirology 17(2): 201-212.
Santana, F. P. R., N. M. Pinheiro, M. I. Bittencourt-Mernak, A. Perini, K. Yoshizaki, M. Macchione, P. H. N. Saldiva, M. A. Martins, I. Tiberio, M. A. M. Prado, V. F. Prado and C. M. Prado (2019). "Vesicular acetylcholine transport deficiency potentiates some inflammatory responses induced by diesel exhaust particles." Ecotoxicol Environ Saf 167: 494-504.
Savary, C. C., N. Bellamri, C. Morzadec, S. Langouet, V. Lecureur and L. Vernhet (2018). "Long term exposure to environmental concentrations of diesel exhaust particles does not impact the phenotype of human bronchial epithelial cells." Toxicol In Vitro 52: 154-160.
Schieber, M. and N. S. Chandel (2014). "ROS function in redox signaling and oxidative stress." Curr Biol 24(10): R453-462.
Schmidt, C. W. (2007). "Biodiesel: cultivating alternative fuels." Environ Health Perspect 115(2): A86-91.
Steiner, S., C. Bisig, A. Petri-Fink and B. Rothen-Rutishauser (2016). "Diesel exhaust: current knowledge of adverse effects and underlying cellular mechanisms." Arch Toxicol 90(7): 1541-1553.
Thiery, J. P., H. Acloque, R. Y. Huang and M. A. Nieto (2009). "Epithelial-mesenchymal transitions in development and disease." Cell 139(5): 871-890.
Traverso, N., R. Ricciarelli, M. Nitti, B. Marengo, A. L. Furfaro, M. A. Pronzato, U. M. Marinari and C. Domenicotti (2013). "Role of glutathione in cancer progression and chemoresistance." Oxid Med Cell Longev 2013: 972913.
Valsecchi, F., L. S. Ramos-Espiritu, J. Buck, L. R. Levin and G. Manfredi (2013). "cAMP and mitochondria." Physiology (Bethesda) 28(3): 199-209.
van der Toorn, M., M. P. Smit-de Vries, D. J. Slebos, H. G. de Bruin, N. Abello, A. J. van Oosterhout, R. Bischoff and H. F. Kauffman (2007). "Cigarette smoke irreversibly modifies glutathione in airway epithelial cells." Am J Physiol Lung Cell Mol Physiol 293(5): L1156-1162.
Vattanasit, U., P. Navasumrit, M. B. Khadka, J. Kanitwithayanun, J. Promvijit, H. Autrup and M. Ruchirawat (2014). "Oxidative DNA damage and inflammatory responses in cultured human cells and in humans exposed to traffic-related particles." Int J Hyg Environ Health 217(1): 23-33.
Vilcassim, M. J. R., G. D. Thurston, L. C. Chen, C. C. Lim, E. Saunders, Y. Yao and T. Gordon (2019). "Exposure to air pollution is associated with adverse cardiopulmonary health effects in international travellers." J Travel Med 26(5). Wang, N., Q. Li, H. Liu, L. Lin, W. Han and W. Hao (2019). "Role of C/EBPalpha
hypermethylation in diesel engine exhaust exposure-induced lung inflammation." Ecotoxicol Environ Saf 183: 109500.
Wang, Q., Y. Wang, Y. Zhang, Y. Zhang and W. Xiao (2013). "The role of uPAR in epithelial-mesenchymal transition in small airway epithelium of patients with chronic obstructive pulmonary disease." Respir Res 14: 67.
WHO (2006). WHO Air quality guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide. Global update 2005. Geneva, WHO.
228
Wichmann, H. E. (2007). "Diesel exhaust particles." Inhal Toxicol 19 Suppl 1: 241-244. Xu, Y., L. Barregard, J. Nielsen, A. Gudmundsson, A. Wierzbicka, A. Axmon, B. A.
Jonsson, M. Karedal and M. Albin (2013). "Effects of diesel exposure on lung function and inflammation biomarkers from airway and peripheral blood of healthy volunteers in a chamber study." Part Fibre Toxicol 10: 60.
Zhang, L. P., X. Zhang, H. W. Duan, T. Meng, Y. Niu, C. F. Huang, W. M. Gao, S. F. Yu and Y. X. Zheng (2017). "Long-term exposure to diesel engine exhaust induced lung function decline in a cross sectional study." Ind Health 55(1): 13-26.
Zhao, H., J. K. Ma, M. W. Barger, R. R. Mercer, L. Millecchia, D. Schwegler-Berry, V. Castranova and J. Y. Ma (2009). "Reactive oxygen species- and nitric oxide-mediated lung inflammation and mitochondrial dysfunction in wild-type and iNOS-deficient mice exposed to diesel exhaust particles." J Toxicol Environ Health A 72(8): 560-570.
Zin, W. A., A. G. Silva, C. B. Magalhaes, G. M. Carvalho, D. R. Riva, C. C. Lima, J. H. Leal-Cardoso, C. M. Takiya, S. S. Valenca, P. H. Saldiva and D. S. Faffe (2012). "Eugenol attenuates pulmonary damage induced by diesel exhaust particles." J Appl Physiol (1985) 112(5): 911-917.
Zuo, H., I. Cattani-Cavalieri, S. S. Valenca, N. Musheshe and M. Schmidt (2019). "Function of cAMP scaffolds in obstructive lung disease: Focus on epithelial-to-mesenchymal transition and oxidative stress." Br J Pharmacol 176(14): 2402-2415.
Zuo, H., M. Trombetta-Lima, I. H. Heijink, C. van der Veen, L. Hesse, K. N. Faber, W. J. Poppinga, H. Maarsingh, V. O. Nikolaev and A. M. Schmidt (2020). "A-Kinase Anchoring Proteins Diminish TGF-beta1/Cigarette Smoke-Induced Epithelial-To-Mesenchymal Transition." Cells 9(2).
