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      Haemophilus influenzae persists in biofilm communities in a smoke-exposed ferret model of COPD

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          Abstract

          Rationale

          Non-typeable Haemophilus influenzae (NTHi) is a common inhabitant of the human nasopharynx and upper airways that can cause opportunistic infections of the airway mucosa including bronchopulmonary infections in patients with chronic obstructive pulmonary disease (COPD). It is clear that opportunistic infections contribute significantly to inflammatory exacerbations of COPD; however, there remains much to be learned regarding specific host and microbial determinants of persistence and/or clearance in this context.

          Methods

          In this study, we used a recently described ferret model for COPD, in which animals undergo chronic long-term exposure to cigarette smoke, to define host–pathogen interactions during COPD-related NTHi infections.

          Results

          NTHi bacteria colonised the lungs of smoke-exposed animals to a greater extent than controls, and elicited acute host inflammation and neutrophilic influx and activation, along with a significant increase in airway resistance and a decrease in inspiratory capacity consistent with inflammatory exacerbation; notably, these findings were not observed in air-exposed control animals. NTHi bacteria persisted within multicellular biofilm communities within the airway lumen, as evidenced by immunofluorescent detection of bacterial aggregates encased within a sialylated matrix as is typical of NTHi biofilms and differential bacterial gene expression consistent with the biofilm mode of growth.

          Conclusions

          Based on these results, we conclude that acute infection with NTHi initiates inflammatory exacerbation of COPD disease. The data also support the widely held hypothesis that NTHi bacteria persist within multicellular biofilm communities in the lungs of patients with COPD.

          Abstract

          Infection of smoke-exposed ferrets with COPD results in mucus obstruction and respiratory symptoms as in patients, and the bacteria are in a distinct mode of growth consistent with biofilms https://bit.ly/3euXpbQ

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          Most cited references34

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          Susceptibility to exacerbation in chronic obstructive pulmonary disease.

          Although we know that exacerbations are key events in chronic obstructive pulmonary disease (COPD), our understanding of their frequency, determinants, and effects is incomplete. In a large observational cohort, we tested the hypothesis that there is a frequent-exacerbation phenotype of COPD that is independent of disease severity. We analyzed the frequency and associations of exacerbation in 2138 patients enrolled in the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) study. Exacerbations were defined as events that led a care provider to prescribe antibiotics or corticosteroids (or both) or that led to hospitalization (severe exacerbations). Exacerbation frequency was observed over a period of 3 years. Exacerbations became more frequent (and more severe) as the severity of COPD increased; exacerbation rates in the first year of follow-up were 0.85 per person for patients with stage 2 COPD (with stage defined in accordance with Global Initiative for Chronic Obstructive Lung Disease [GOLD] stages), 1.34 for patients with stage 3, and 2.00 for patients with stage 4. Overall, 22% of patients with stage 2 disease, 33% with stage 3, and 47% with stage 4 had frequent exacerbations (two or more in the first year of follow-up). The single best predictor of exacerbations, across all GOLD stages, was a history of exacerbations. The frequent-exacerbation phenotype appeared to be relatively stable over a period of 3 years and could be predicted on the basis of the patient's recall of previous treated events. In addition to its association with more severe disease and prior exacerbations, the phenotype was independently associated with a history of gastroesophageal reflux or heartburn, poorer quality of life, and elevated white-cell count. Although exacerbations become more frequent and more severe as COPD progresses, the rate at which they occur appears to reflect an independent susceptibility phenotype. This has implications for the targeting of exacerbation-prevention strategies across the spectrum of disease severity. (Funded by GlaxoSmithKline; ClinicalTrials.gov number, NCT00292552.)
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            Oxidative stress in COPD.

            Oxidative stress is now recognized as a major predisposing factor in the pathogenesis of COPD. Existing therapies for COPD are ineffective at halting disease progression, with bronchodilators being the mainstay of pharmacotherapy, providing symptomatic relief only. It is, therefore, important for a better understanding of the underlying mechanisms by which oxidative stress drives disease pathogenesis to develop novel and more effective therapies. Antioxidant capacity in COPD is substantially reduced as a result of cigarette smoking and exacerbations, with oxidative stress persisting long after the cessation of cigarette smoking or exacerbation, due to the continued production of reactive oxygen species from endogenous sources. We discuss (1) how oxidative stress arises in the lung, (2) how it is neutralized, (3) what genetic factors may predispose to the development of COPD, and (4) how this impacts inflammation and autoimmunity in the development of emphysema and small airways disease. Finally, various strategies have been considered to neutralize the increased oxidative burden present in COPD. This review highlights why current antioxidant strategies have so far failed and what promising alternatives are on the horizon. Moreover, a number of studies have shown that there is no single "magic bullet" to combat oxidative stress, but instead a combination therapy, targeting oxidative stress in the various subcellular compartments, may prove to be more effective in COPD.
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              Chronic obstructive pulmonary disease.

              Chronic obstructive pulmonary disease (COPD) is a common disease with high global morbidity and mortality. COPD is characterized by poorly reversible airway obstruction, which is confirmed by spirometry, and includes obstruction of the small airways (chronic obstructive bronchiolitis) and emphysema, which lead to air trapping and shortness of breath in response to physical exertion. The most common risk factor for the development of COPD is cigarette smoking, but other environmental factors, such as exposure to indoor air pollutants - especially in developing countries - might influence COPD risk. Not all smokers develop COPD and the reasons for disease susceptibility in these individuals have not been fully elucidated. Although the mechanisms underlying COPD remain poorly understood, the disease is associated with chronic inflammation that is usually corticosteroid resistant. In addition, COPD involves accelerated ageing of the lungs and an abnormal repair mechanism that might be driven by oxidative stress. Acute exacerbations, which are mainly triggered by viral or bacterial infections, are important as they are linked to a poor prognosis. The mainstay of the management of stable disease is the use of inhaled long-acting bronchodilators, whereas corticosteroids are beneficial primarily in patients who have coexisting features of asthma, such as eosinophilic inflammation and more reversibility of airway obstruction. Apart from smoking cessation, no treatments reduce disease progression. More research is needed to better understand disease mechanisms and to develop new treatments that reduce disease activity and progression.
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                Author and article information

                Journal
                ERJ Open Res
                ERJ Open Res
                ERJOR
                erjor
                ERJ Open Research
                European Respiratory Society
                2312-0541
                July 2020
                11 August 2020
                : 6
                : 3
                : 00200-2020
                Affiliations
                [1 ]Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham School of Medicine, Birmingham, AL, USA
                [2 ]Gregory Fleming James Center for Cystic Fibrosis Research, University of Alabama at Birmingham School of Medicine, Birmingham, AL, USA
                Author notes
                W. Edward Swords, 1918 University Boulevard, MCLM760, Birmingham, AL 35294, USA. E-mail: wswords@ 123456uabmc.edu
                Author information
                https://orcid.org/0000-0003-3947-4871
                Article
                00200-2020
                10.1183/23120541.00200-2020
                7418822
                80cb75a0-1467-4457-b886-95f11431f01a
                Copyright ©ERS 2020

                This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial Licence 4.0.

                History
                : 19 April 2020
                : 18 May 2020
                Funding
                Funded by: National Institute of Diabetes and Digestive and Kidney Diseases, open-funder-registry 10.13039/100000062;
                Award ID: P30 DK072482
                Funded by: National Heart, Lung, and Blood Institute, open-funder-registry 10.13039/100000050;
                Award ID: R35 HL135816
                Award ID: T32 134640
                Funded by: National Institute of Allergy and Infectious Diseases, open-funder-registry 10.13039/100000060;
                Award ID: R21 AI133445
                Categories
                Original Articles
                COPD
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                12

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