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Sansores RH, Paulin-Prado P, Robles-Hernández R, Montiel-Lopez F, Bautista-Félix NE, Guzmán-Bouilloud NE, Falfán-Valencia R, Pérez-Rubio G, Hernández-Zenteno RDJ, Flores-Trujillo F, Pérez-Bautista O, Ramírez-Venegas A. Clinical and microbiological characteristics and inflammatory profile during an exacerbation of COPD due to biomass exposure. A comparison with COPD due to tobacco exposure. Respir Med 2022; 204:107010. [DOI: 10.1016/j.rmed.2022.107010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/01/2022] [Accepted: 10/08/2022] [Indexed: 10/31/2022]
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Chen X, Luan M, Liu J, Yao Y, Li X, Wang T, Zhang H, Han Y, Lu X, Chen W, Hu X, Zheng M, Qiu X, Zhu T. Risk factors in air pollution exposome contributing to higher levels of TNFα in COPD patients. ENVIRONMENT INTERNATIONAL 2022; 159:107034. [PMID: 34906887 DOI: 10.1016/j.envint.2021.107034] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 11/30/2021] [Accepted: 12/05/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Air pollutants are found associated with various health effects in chronic obstructive pulmonary patients. Given the complicate chemical components of air pollutants, it is not clear which components are the main risk factors for these health effects. OBJECTIVES Based on the COPD in Beijing (COPDB) study and exposome concept, we examined comprehensively the air pollution components to screen out high-risk factors for systemic inflammation of COPD patients. METHODS Concentrations of PM with aerodynamic diameter ≤ 2.5 μm (PM2.5), ultrafine and accumulated-mode particles (UFPs and Acc), PM2.5-contained carbonaceous components/elements/water soluble ions, gaseous pollutants, temperature, and relative humidity (RH) were continuously monitored around participants. Urinary polycyclic aromatic hydrocarbons (PAHs) and cotinine, and serum tumor necrosis factor α (TNFα) were measured from 53 COPD and 82 non-COPD participants. Lifestyle variables were recorded using follow-up questionnaire. Linear mixed effects (LME) models were used to assess the associations of TNFα differences with exposure to air pollutants, meteorological variations, and lifestyle. RESULTS In COPD patients, the associations of TNFα differences with exposure to ozone, Cd, UFPs, Acc, 2-hydroxydibenzofuran, temperature and RH parameters, and several elements in PM2.5 were significant in certain time-windows. For example, per interquartile range (IQR) increase in average ozone concentration 14 d before visits was associated with 17.3% (95% confidence interval: 6.8%, 27.7%) TNFα difference. Associations between ozone, Cd, UFPs, Acc, the maximum value of RH, and 2-hydroxydibenzofuran exposure and TNFα differences remained robust in two-pollutant models, and contributed to 19.0%, 10.5%, 2.2%, 1.6%, 2.1%, and 1.5% TNFα differences, respectively. Among the high-risk factors for COPD patients, the responses to UFPs, Acc, and 2-hydroxydibenzofuran were not robust in non-COPD participants. DISCUSSION Ozone, Cd, UFPs, Acc, PAHs exposure and RH variation were high-risk factors of systemic inflammation for COPD patients, and the profile of high-risk factors were different from those in general population.
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Affiliation(s)
- Xi Chen
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; Hebei Technology Innovation Center of Human Settlement in Green Building, Shenzhen Institute of Building Research Co., Ltd., Xiongan 071700, China
| | - Mengxiao Luan
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Jinming Liu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Yuan Yao
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Xiaoying Li
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Teng Wang
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Hanxiyue Zhang
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Yiqun Han
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; Department of Epidemiology and Biostatistics, MRC Centre for Environmental and Health, Imperial College London, SW7 2AZ, UK
| | - Xinchen Lu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Wu Chen
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Xinyan Hu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Mei Zheng
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Xinghua Qiu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Tong Zhu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
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Chen X, Que C, Yao Y, Han Y, Zhang H, Li X, Lu X, Chen W, Hu X, Wu Y, Wang T, Zhang L, Zheng M, Qiu X, Zhu T. Susceptibility of individuals with lung dysfunction to systemic inflammation associated with ambient fine particle exposure: A panel study in Beijing. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 788:147760. [PMID: 34020092 DOI: 10.1016/j.scitotenv.2021.147760] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 05/02/2021] [Accepted: 05/10/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND The underlying mechanism on the susceptibility of chronic obstructive pulmonary disease (COPD) patients to air pollution has yet to be clarified. OBJECTIVES Based on the COPD in Beijing (COPDB) study, we examined whether lung dysfunction contributed to pollutant-associated systemic inflammation in COPD patients. METHODS Proinflammatory biomarkers including interleukin-8 (IL-8) and tumor necrosis factor α (TNFα) were measured in serum samples collected from 53 COPD and 82 healthy participants. Concentrations of particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5), carbonaceous components in PM2.5, and PM size distribution were continuously monitored. Linear mixed effects models were used to examine the associations of biomarker differences with particle exposure, between COPD and healthy participants, and across subgroups with different levels of lung dysfunction. RESULTS COPD patients showed higher differences in IL-8 and TNFα levels associated with exposure to measured pollutants, comparing to healthy controls. In advanced analysis, particle-associated differences in IL-8 and TNFα levels were higher in participants with poorer lung ventilation and diffusion capacity, and higher ratio of residual volume. For example, an interquartile range increase in average PM2.5 concentration 2 weeks before visits was associated with a 15.7% difference in IL-8 level in participants with the lowest ratio of measured value to predicted value of forced expiratory volume in 1 s (FEV1%pred) (65.2%), and the association decreased monotonically with increasing FEV1%pred. Associations between differences in TNFα level and average ultrafine particle concentration 1 week before visits increased gradually with increasing ratio of measured value to predicted value of residual volume/total lung capacity. CONCLUSIONS COPD patients, especially those with poorer lung function, are more susceptible to systemic inflammation associated with fine particle exposure.
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Affiliation(s)
- Xi Chen
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; GRiC, Shenzhen Institute of Building Research Co., Ltd., Xiong'an 071700, China.
| | - Chengli Que
- Peking University First Hospital, Peking University, Beijing 100034, China.
| | - Yuan Yao
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Yiqun Han
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; Department of Epidemiology and Biostatistics, MRC Centre for Environmental and Health, Imperial College London, SW7 2AZ, UK.
| | - Hanxiyue Zhang
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Xiaoying Li
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Xinchen Lu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Wu Chen
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Xinyan Hu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Yusheng Wu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Teng Wang
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Lina Zhang
- Beijing Xicheng District Shichahai Community Health Center, Beijing 100000, China.
| | - Mei Zheng
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Xinghua Qiu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Tong Zhu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
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Chen X, Wang T, Qiu X, Que C, Zhang H, Zhang L, Zhu T. Susceptibility of individuals with chronic obstructive pulmonary disease to air pollution exposure in Beijing, China: A case-control panel study (COPDB). THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 717:137285. [PMID: 32092811 DOI: 10.1016/j.scitotenv.2020.137285] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 06/10/2023]
Abstract
Exposure to air pollution is one of the major risk factors contributing to the occurrence and development of chronic obstructive pulmonary disease (COPD). However, few studies have investigated the susceptibility of patients with COPD to air pollution. Here, we provided a study protocol. A panel study of a total of 480 samples to compare the response to air pollution exposure between 60 patients with COPD and 60 healthy control subjects has been performed in Beijing (the COPDB study) since May 2016. The health assessment and exposure evaluation methods used in this COPDB study are summarized here. Throat, exhaled breath and condensate, urine, serum, plasma, and blood samples, as well as cardiopulmonary function indexes were repeatedly collected over four visits. Indicators of inflammation, oxidative stress, infection, metabolic changes, and genetic differences were then analyzed. Personal and ambient levels of fine particles and their components, as well as gaseous pollutants were monitored during the follow-up period. Linear mixed-effects models were used to evaluate the associations between changes in biomarkers and exposure to air pollution in both patients with COPD and healthy control subjects. Based on the COPDB study, the susceptibility of COPD patients and underlying mechanisms, involving difference in inflammatory, infection, metabolic, and genetic response to different air pollutants, were investigated. Our preliminary result shows that air pollution-associated changes in heart rate were higher in COPD patients than the healthy controls. More investigations of the underlying mechanisms of the susceptibility are ongoing. This study has been registered in ChiCTR with the number of ChiCTR1900023692.
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Affiliation(s)
- Xi Chen
- State Key Joint Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China; The Beijing Innovation Center for Engineering Science and Advanced Technology, College of Environmental Sciences and Engineering, Peking University, Beijing, China; GRiC, Shenzhen Institute of Building Research Co., Ltd., Shenzhen, China.
| | - Teng Wang
- State Key Joint Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China; The Beijing Innovation Center for Engineering Science and Advanced Technology, College of Environmental Sciences and Engineering, Peking University, Beijing, China.
| | - Xinghua Qiu
- State Key Joint Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China.
| | - Chengli Que
- Peking University First Hospital, Peking University, Beijing, China.
| | - Hanxiyue Zhang
- State Key Joint Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China.
| | - Lina Zhang
- Beijing Xicheng District Shichahai Community Health Center, Beijing, China.
| | - Tong Zhu
- State Key Joint Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China; The Beijing Innovation Center for Engineering Science and Advanced Technology, College of Environmental Sciences and Engineering, Peking University, Beijing, China.
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Cheng LL, Liu YY, Su ZQ, Liu J, Chen RC, Ran PX. Clinical characteristics of tobacco smoke-induced versus biomass fuel-induced chronic obstructive pulmonary disease. J Transl Int Med 2015; 3:126-129. [PMID: 27847900 PMCID: PMC4936465 DOI: 10.1515/jtim-2015-0012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVE To investigate differences in clinical features between tobacco smoke-induced and biomass fuel-induced chronic obstructive pulmonary disease (COPD). METHODS We retrospectively analyzed 206 patients with COPD caused by exposure to tobacco smoke and 81 cases of COPD caused by exposure to biomass fuels who received treatment in our hospital between 2011 March and 2014 March. Difference in general health status, clinical symptoms, the dyspnea score, and comorbidities between the two groups were compared. In addition, pulmonary function, grading, and acute exacerbations were also compared. RESULTS (1) Difference in general health status: Male and female patients with COPD caused by exposure to tobacco smoke were 83.5 and 16.5%, respectively. Male and female patients with COPD caused by exposure to smoke from biomass fuels were 14.8 and 85.2% (χ2 = 27.2, P < 0.05), respectively. Tobacco smoke-induced COPD was more prevalent in men, and COPD caused by exposure to smoke from biomass fuels was more prevalent in women. After gender adjustment, body mass index (BMI) was lower in women with COPD caused by exposure to smoke from biomass fuels than those by tobacco smoke. There was no statistically significant difference in other indicators, such as age. (2): Difference in clinical symptoms: No statistically significant difference in the modified British Medical Research Counsel (mMRC) Questionnaire, a measure of breathlessness, was observed between the two groups. Dyspnea was more common in COPD patients that was caused by exposure to biomass fuels (38.3%) than by tobacco smoke (11.1%) (χ2 = 17.9, P < 0.05). The comorbidities of allergic diseases (such as allergic rhinitis, bronchial asthma) were more prevalent in COPD patients that was caused by exposure to smoke from biomass fuels (43.2%) than by tobacco smoke (18%) (χ2 = 16.1, P < 0.05). However, COPD comorbid with lung cancer was more prevalent in those cases that were caused by exposure to tobacco smoke (7.77%) than in cases caused by exposure to smoke from biomass fuels (3.7%) (χ2 = 9.7, P < 0.05). (3) Differences in grading of pulmonary function: After gender adjustment, patients with COPD caused by exposure to biomass fuels were mostly in grade B or D. (4) Exacerbations: No significant difference in exacerbations per year was noted between the two groups. CONCLUSIONS Marked differences exist between patients with COPD caused by exposure to tobacco smoke and smoke from biomass fuels. Patients with COPD caused by exposure to biofuels are mostly females with lower BMI and often with many clinical symptoms and complications, such as allergic rhinitis and bronchial asthma. Such patients are often in stage B or D. Tobacco smoke-induced COPD is more prevalent in male patients, often with complications in the form of lung cancer.
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Affiliation(s)
- Lin-ling Cheng
- The Key State Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, Guangdong Province, China
| | - Ya-ya Liu
- Guangzhou Profession College of Foods and Drugs, Guangzhou 510120, Guangdong Province, China
| | - Zhu-quan Su
- The Key State Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, Guangdong Province, China
| | - Jun Liu
- The Key State Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, Guangdong Province, China
| | - Rong-chang Chen
- The Key State Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, Guangdong Province, China
| | - Pi-xin Ran
- The Key State Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, Guangdong Province, China
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Silva R, Oyarzún M, Olloquequi J. Pathogenic Mechanisms in Chronic Obstructive Pulmonary Disease Due to Biomass Smoke Exposure. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.arbr.2015.04.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Silva R, Oyarzún M, Olloquequi J. Pathogenic mechanisms in chronic obstructive pulmonary disease due to biomass smoke exposure. Arch Bronconeumol 2015; 51:285-92. [PMID: 25614376 DOI: 10.1016/j.arbres.2014.10.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/12/2014] [Accepted: 10/14/2014] [Indexed: 12/31/2022]
Abstract
Chronic obstructive pulmonary disease (COPD) mortality and morbidity have increased significantly worldwide in recent decades. Although cigarette smoke is still considered the main risk factor for the development of the disease, estimates suggest that between 25% and 33% of COPD patients are non-smokers. Among the factors that may increase the risk of developing COPD, biomass smoke has been proposed as one of the most important, affecting especially women and children in developing countries. Despite the epidemiological evidence linking exposure to biomass smoke with adverse health effects, the specific cellular and molecular mechanisms by which this pollutant can be harmful for the respiratory and cardiovascular systems remain unclear. In this article we review the main pathogenic mechanisms proposed to date that make biomass smoke one of the major risk factors for COPD.
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Affiliation(s)
- Rafael Silva
- Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
| | - Manuel Oyarzún
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Jordi Olloquequi
- Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile.
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Bezemer GFG, Sagar S, van Bergenhenegouwen J, Georgiou NA, Garssen J, Kraneveld AD, Folkerts G. Dual role of Toll-like receptors in asthma and chronic obstructive pulmonary disease. Pharmacol Rev 2012; 64:337-58. [PMID: 22407613 DOI: 10.1124/pr.111.004622] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
During the last decade, significant research has been focused on Toll-like receptors (TLRs) in the pathogenesis of airway diseases. TLRs are pattern recognition receptors that play pivotal roles in the detection of and response to pathogens. Because of the involvement of TLRs in innate and adaptive immunity, these receptors are currently being exploited as possible targets for drug development. Asthma and chronic obstructive pulmonary disease (COPD) are chronic inflammatory airway diseases in which innate and adaptive immunity play an important role. To date, asthma is the most common chronic disease in children aged 5 years and older. COPD is prevalent amongst the elderly and is currently the fifth-leading cause of death worldwide with still-growing prevalence. Both of these inflammatory diseases result in shortness of breath, which is treated, often ineffectively, with bronchodilators and glucocorticosteroids. Symptomatic treatment approaches are similar for both diseases; however, the underlying immunological mechanisms differ greatly. There is a clear need for improved treatment specific for asthma and for COPD. This review provides an update on the role of TLRs in asthma and in COPD and discusses the merits and difficulties of targeting these proteins as novel treatment strategies for airway diseases. TLR agonist, TLR adjuvant, and TLR antagonist therapies could all be argued to be effective in airway disease management. Because of a possible dual role of TLRs in airway diseases with shared symptoms and risk factors but different immunological mechanisms, caution should be taken while designing pulmonary TLR-based therapies.
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Affiliation(s)
- Gillina F G Bezemer
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
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Lopes FDTQS, Pinto TS, Arantes-Costa FM, Moriya HT, Biselli PJC, Ferraz LFS, Lichtenfels AJ, Saldiva PH, Mauad T, Martins MA. Exposure to ambient levels of particles emitted by traffic worsens emphysema in mice. ENVIRONMENTAL RESEARCH 2009; 109:544-551. [PMID: 19362299 DOI: 10.1016/j.envres.2009.03.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 02/26/2009] [Accepted: 03/03/2009] [Indexed: 05/27/2023]
Abstract
OBJECTIVES We investigated effects of chronic exposure (2 months) to ambient levels of particulate matter (PM) on development of protease-induced emphysema and pulmonary remodeling in mice. METHODS Balb/c mice received nasal drop of either papain or normal saline and were kept in two exposure chambers situated in an area with high traffic density. One of them received ambient air and the other had filters for PM. RESULTS mean concentration of PM10 was 2.68 +/- 0.38 and 33.86 +/- 2.09 microg/m3, respectively, in the filtered and ambient air chambers (p < 0.001). After 2 months of exposure, lungs from papain-treated mice kept in the chamber with ambient air presented greater values of mean linear intercept, an increase in density of collagen fibers in alveolar septa and in expression of 8-isoprostane (p = 0.002, p < 0.05 and p = 0.002, respectively, compared to papain-treated mice kept in the chamber with filtered air). We did not observe significant differences between these two groups in density of macrophages and in amount of cells expressing matrix metalloproteinase-12. There were no significant differences in saline-treated mice kept in the two chambers. CONCLUSIONS We conclude that exposure to urban levels of PM worsens protease-induced emphysema and increases pulmonary remodeling. We suggest that an increase in oxidative stress induced by PM exposure influences this response. These pulmonary effects of PM were observed only in mice with emphysema.
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