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Chronic obstructive pulmonary disease (COPD) is associated with chronic inflammation affecting predominantly the lung parenchyma and peripheral airways that results in largely irreversible and progressive airflow limitation. This inflammation is characterized by increased numbers of alveolar macrophages, neutrophils, T lymphocytes (predominantly TC1, TH1, and TH17 cells), and innate lymphoid cells recruited from the circulation. These cells and structural cells, including epithelial and endothelial cells and fibroblasts, secrete a variety of proinflammatory mediators, including cytokines, chemokines, growth factors, and lipid mediators. Although most patients with COPD have a predominantly neutrophilic inflammation, some have an increase in eosinophil counts, which might be orchestrated by TH2 cells and type 2 innate lymphoid cells though release of IL-33 from epithelial cells. These patients might be more responsive to corticosteroids and bronchodilators. Oxidative stress plays a key role in driving COPD-related inflammation, even in ex-smokers, and might result in activation of the proinflammatory transcription factor nuclear factor κB (NF-κB), impaired antiprotease defenses, DNA damage, cellular senescence, autoantibody generation, and corticosteroid resistance though inactivation of histone deacetylase 2. Systemic inflammation is also found in patients with COPD and can worsen comorbidities, such as cardiovascular diseases, diabetes, and osteoporosis. Accelerated aging in the lungs of patients with COPD can also generate inflammatory protein release from senescent cells in the lung. In the future, it will be important to recognize phenotypes of patients with optimal responses to more specific therapies, and development of biomarkers that identify the therapeutic phenotypes will be important.

Inflammatory mechanisms in patients with 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.

https://www.medicinejournal.co.uk/article/S1357-3039(06)00582-2/pdf

Chronic obstructive pulmonary disease.

https://www.thelancet.com/pdfs/journals/lanres/PIIS2213-2600(14)70001-3.pdf

Minimum clinically important difference for the COPD Assessment Test: a prospective analysis

https://www.thelancet.com/pdfs/journals/lanres/PIIS2213-2600(15)00241-6.pdf

Risk of cardiovascular comorbidity in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis

Background Prevalence and load of airway bacteria in stable and exacerbated chronic obstructive pulmonary disease (COPD) has been previously studied using microbiological culture. Molecular techniques, such as quantitative PCR (qPCR), may be more informative.

Methods In this study, 373 sputum samples from 134 COPD outpatients were assessed for prevalence and load of typical airway bacteria (Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis) by multiplex qPCR, with 176 samples analysed for atypical bacteria. Paired stable and exacerbation typical bacteria data were compared in 52 patients. We compared routine culture with qPCR in 177/373 samples.

Results Typical bacteria were more prevalent in exacerbation than stable-state paired samples: 30/52 (57.7%) vs. 14/52 (26.9%); p=0.001. In patients who were bacteria-positive at both time points, mean (±1 SEM) load was significantly higher at exacerbation than stable state (108.5(±0.3) vs. 107.2(±0.5) cfu/ml), constituting a 20-fold increase (p=0.011). qPCR was more discriminatory at detecting typical bacteria than microbiological culture (prevalence 59.3% vs. 24.3%; p<0.001). At stable state, higher airway bacterial load correlated with more severe airflow limitation (FEV1%predicted) (r=−0.299; p=0.033) and higher inhaled corticosteroid dosage (r=0.382; p=0.008). Mean C-reactive protein was higher in bacterial-associated exacerbations (35.0 Vs 25.1 mg/L; p=0.032).

Conclusions Airway bacterial prevalence and load increase at COPD exacerbations and are an aetiological factor. qPCR is more discriminatory than culture, identifying higher airway bacterial prevalence. Exacerbations associated with bacterial detection showed a higher mean C-reactive protein level. In the stable state, airway bacterial load is related to more severe airflow limitation and higher inhaled corticosteroid dosage used.

https://thorax.bmj.com/content/thoraxjnl/67/12/1075.full.pdf

Changes in prevalence and load of airway bacteria using quantitative PCR in stable and exacerbated COPD

Rationale: The Chronic Obstructive Pulmonary Disease (COPD) Assessment Test (CAT) is an eight-item questionnaire designed to assess and quantify the impact of COPD symptoms on health status. COPD exacerbations impair quality of life and are characterized by worsening respiratory symptoms from the stable state. We hypothesized that CAT scores at exacerbation relate to exacerbation severity as measured by exacerbation duration, lung function impairment, and systemic inflammation.Objectives: To evaluate the usefulness of the CAT to assess exacerbation severity.Methods: One hundred sixty-one patients enrolled in the London COPD cohort completed the CAT at baseline (stable state), exacerbation, and during recovery between April 2010 and June 2011.Measurements and Main Results: Frequent exacerbators had significantly higher baseline CAT scores than infrequent exacerbators (19.5 ± 6.6 vs. 16.8 ± 8.0, P = 0.025). In 152 exacerbations, CAT scores rose from an average baseline value of 19.4 ± 6.8 to 24.1 ± 7.3 (P <...

https://www.atsjournals.org/doi/pdf/10.1164/rccm.201110-1843OC

Usefulness of the Chronic Obstructive Pulmonary Disease Assessment Test to Evaluate Severity of COPD Exacerbations

Extrapulmonary comorbidities are common and significant in chronic obstructive pulmonary disease (COPD), often contributing to symptoms, exacerbations, hospital admissions and mortality. Cardiovascular, musculoskeletal and psychological conditions are among the most prevalent and important of these. In particular, ischemic heart disease is a leading cause of death in the COPD population as a whole. Here, we provide a state-of-the-art summary of key comorbidities observed in COPD patients in terms of their prevalence, impact, pathophysiology and prognosis. In addition, we review clinical, diagnostic and management strategies that may differ in COPD patients from the rest of the population.

https://www.tandfonline.com/doi/pdf/10.1586/ers.11.62

Extrapulmonary comorbidities in chronic obstructive pulmonary disease: state of the art

Rationale: Patients with chronic obstructive pulmonary disease (COPD) have elevated cardiovascular risk, and myocardial injury is common during severe exacerbations. Little is known about the prevalence, magnitude, and underlying mechanisms of cardiovascular risk in community-treated exacerbations.

Objectives: To investigate how COPD exacerbations and exacerbation frequency impact cardiovascular risk and myocardial injury, and whether this is related to airway infection and inflammation.

Methods: We prospectively measured arterial stiffness (aortic pulse wave velocity [aPWV]) and cardiac biomarkers in 98 patients with stable COPD. Fifty-five patients had paired stable and exacerbation assessments, repeated at Days 3, 7, 14, and 35 during recovery. Airway infection was identified using polymerase chain reaction.

Measurements and Main Results: COPD exacerbation frequency was related to stable-state arterial stiffness (rho = 0.209; P = 0.040). Frequent exacerbators had greater aPWV than infrequent exacerbators (mean ± SD aPWV, 11.4 ± 2.1 vs. 10.3 ± 2.0 ms−1; P = 0.025). Arterial stiffness rose by an average of 1.2 ms−1 (11.1%) from stable state to exacerbation (n = 55) and fell slowly during recovery. In those with airway infection at exacerbation (n = 24) this rise was greater (1.4 ± 1.6 vs. 0.7 ± 1.3 ms−1; P = 0.048); prolonged; and related to sputum IL-6 (rho = 0.753; P < 0.001). Increases in cardiac biomarkers at exacerbation were higher in those with ischemic heart disease (n = 12) than those without (n = 43) (mean ± SD increase in troponin T, 0.011 ± 0.009 vs. 0.003 ± 0.006 μg/L, P = 0.003; N-terminal pro–brain natriuretic peptide, 38.1 ± 37.7 vs. 5.9 ± 12.3 pg/ml, P < 0.001).

Conclusions: Frequent COPD exacerbators have greater arterial stiffness than infrequent exacerbators. Arterial stiffness rises acutely during COPD exacerbations, particularly with airway infection. Increases in arterial stiffness are related to inflammation, and are slow to recover. Myocardial injury is common and clinically significant during COPD exacerbations, particularly in those with underlying ischemic heart disease.

/pdf/cardiovascular-risk-myocardial-injury-and-exacerbations-of-446ln046ai.pdf

Cardiovascular Risk, Myocardial Injury, and Exacerbations of Chronic Obstructive Pulmonary Disease

Human rhinovirus (HRV) infection is an important trigger of exacerbations of chronic obstructive pulmonary disease (COPD) but its role in determining exacerbation frequency phenotype or the time-course of HRV infection in naturally occurring exacerbations is unknown. Sputum samples from 77 patients were analysed by real-time quantitative PCR for both HRV (388 samples), and Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis (89 samples). Patients recorded worsening of respiratory symptoms on daily diary cards, from which exacerbations were identified. HRV prevalence and load at exacerbation presentation were significantly higher than in the stable state (prevalence 53.3% versus 17.2%, respectively; p<0.001) but 0% by day 35 post-exacerbation. HRV load was higher in patients with cold symptoms (p=0.046) or sore throats (p=0.006) than those without. 73% of bacterium-negative but HRV-positive exacerbations were bacterium-positive by day 14. Patients with HRV detected at exacerbation had a higher exacerbation frequency (interquartile range) of 3.01 (2.02-5.30) per year compared with patients without HRV (2.51 (2.00-3.51)) (p=0.038). HRV prevalence and load increased at COPD exacerbation, and resolved during recovery. Frequent exacerbators were more likely to experience HRV infection. Secondary bacterial infection is common after HRV infection, and provides a possible mechanism for exacerbation recurrence and a potential target for novel therapies.

https://erj.ersjournals.com/content/erj/44/1/87.full.pdf

Anant R.C. Patel

Papers

Changes in prevalence and load of airway bacteria using quantitative PCR in stable and exacerbated COPD

Usefulness of the Chronic Obstructive Pulmonary Disease Assessment Test to Evaluate Severity of COPD Exacerbations

Extrapulmonary comorbidities in chronic obstructive pulmonary disease: state of the art

Cardiovascular Risk, Myocardial Injury, and Exacerbations of Chronic Obstructive Pulmonary Disease

Human rhinovirus infection during naturally occurring COPD exacerbations