New strains of bacteria and exacerbations of chronic obstructive pulmonary disease

Serum Procalcitonin as a Biomarker for the Prediction of Bacterial Exacerbation and Mortality in Severe COPD Exacerbations Requiring Mechanical Ventilation

BACKGROUND

Procalcitonin (PCT) is being used as a marker of bacterial infections. Although there are several studies showing the diagnostic yield of PCT to differentiate bacterial involvement in chronic obstructive pulmonary disease exacerbations (COPDE), the prognostic yield of PCT in severe COPDE has been studied less.

OBJECTIVES

The primary aim was to determine whether the level of serum PCT at admission in severe COPDE serves as a prognostic biomarker for hospital mortality. The secondary aim was to determine the role of PCT in identifying a bacterial exacerbation.

METHODS

A total of 63 COPDE patients (median age 71 years; male 58.7%) were retrospectively analyzed from our intensive care unit database.

RESULTS

The hospital mortality rate was 23.8%. Admission PCT levels were higher in patients who died during hospitalization (0.66 vs. 0.17 ng/ml; p = 0.014). This association between hospital mortality and serum PCT level remained significant in a multivariate analysis; for every 1 ng/ml increase in PCT level, hospital mortality increased 1.85 times (odds ratio; 95% confidence interval: 1.07-3.19; p = 0.026). The optimal admission PCT threshold was 0.25 ng/ml in order to discern patients who had bacterial exacerbation with a sensitivity of 63%, a specificity of 67%, and a negative predictive value of 80%. The negative predictive value increased to 89% when both the admission and follow-up PCT levels remained <0.25 ng/ml.

CONCLUSION

This study shows that admission PCT levels have a prognostic importance in estimating hospital mortality among patients with severe COPDE. A PCT level <0.25 ng/ml at the time of admission and during follow-up is suggestive of the absence of a bacterial cause of COPDE.

A Sputum Proteomic Signature That Associates with Increased IL-1β Levels and Bacterial Exacerbations of COPD

PURPOSE

Activation of the interleukin-1β (IL-1β) signaling pathway has been implicated in COPD, but the proportion of COPD subjects whose disease is principally driven by activation of this pathway is poorly understood. In this study, we sought to differentiate an IL-1β-associated sputum signature from other inflammation-associated COPD phenotypes.

METHODS

Luminex-multiplex assays were used to study IL-1β-mediated signature proteins within airway epithelium, smooth muscle, and vascular endothelial cell cultures. The IL-1β-mediated signature was tested in a longitudinal study comprising of 35 paired stable-COPD and acute exacerbation (AECOPD) sputum samples. The presence of respiratory pathogens (H. influenzae, M. catarrhalis, S. pneumoniae, and P. aeruginosa) was evaluated by sputum cultures.

RESULTS

Five proteins namely TNF-α, GCSF, IL-6, CD-40L, and MIP-1β were found to be IL-1β-regulated across all donors and cell types. All five of these IL-1β-mediated proteins were significantly increased (p < 0.05) in sputum corresponding to AECOPD events showing at least a twofold increase in IL-1β (IL-1β(+) events, 18 of 35 total events), relative to preceding stable-COPD state. Sputum IL-1β levels showed no significant association (p > 0.05, spearman) with known markers of other major COPD inflammation phenotypes. In addition, there was a significant association with bacterial presence in sputum culture with an odds ratio of 9 (95 % CI 1.56, 51.9) in IL-1β(+) events versus IL-1β(-) events.

CONCLUSION

Our findings provide insights into potential markers of IL-1β-associated AECOPD, and reaffirm association between IL-1β pathway activation and airway bacterial infection in COPD. Taken together, our findings could help identify COPD patient subsets who may benefit from therapies targeting IL-1β pathway.

The clinical management of lower respiratory tract infections

The 2010 Global Burden of Disease Study reported that lower respiratory tract infections, including pneumonia, are the fourth most common cause of death globally. The etiology of acute bronchitis and asthma exacerbations is mostly viral and the therapy is symptomatic. Management decisions in community acquired pneumonia regarding site of care, extent of assessment, and level of treatment are based primarily on disease severity (outpatient, inpatient, ICU admission). Antibiotics are the main choice of treatment for patients with pneumonia, acute exacerbations (AE) of COPD (including increased sputum purulence and worsening shortness of breath) and AE of non-CF bronchiectasis. Inhaled antibiotics may represent a more optimal approach for the treatment and prevention of AE of non-CF bronchiectasis. Approved strategies for the prevention of exacerbations include smoking cessation and rehabilitation programs, drug therapy and vaccination.

Bronchiectasis as a Comorbidity of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Bronchiectasis revealed by chest computed tomography in COPD patients and its comorbid effect on prognosis have not been addressed by large-sized studies. Understanding the presence of bronchiectasis in COPD is important for future intervention and preventing disease progression.

METHODS

Observational studies were identified from electronic literature searches in Cochrane library, PubMed, ScienceDirect databases, American Thoracic Society and European Respiratory Society meeting abstracts. A systematic review and meta-analysis of studies was performed to summarize the factors associated with bronchiectasis in COPD patients. Primary outcomes included the risks for exacerbation frequency, isolation of a potentially pathogenic microorganism, severe airway obstruction and mortality. Odds ratios (ORs) were pooled by random effects models.

RESULTS

Fourteen observational studies were eligible for the study. Compared with COPD without bronchiectasis, comorbid bronchiectasis in COPD increased the risk of exacerbation (1.97, 95% CI, 1.29-3.00), isolation of a potentially pathogenic microorganism (4.11, 95%CI, 2.16-7.82), severe airway obstruction (1.31, 95% CI, 1.09-1.58) and mortality (1.96, 95% CI, 1.04-3.70).

CONCLUSIONS

The presence of bronchiectasis in patients with COPD was associated with exacerbation frequency, isolation of a potentially pathogenic microorganism, severe airway obstruction and mortality.

Dysregulation of Antiviral Function of CD8(+) T Cells in the Chronic Obstructive Pulmonary Disease Lung. Role of the PD-1-PD-L1 Axis

RATIONALE

Patients with chronic obstructive pulmonary disease (COPD) are susceptible to respiratory viral infections that cause exacerbations. The mechanisms underlying this susceptibility are not understood. Effectors of the adaptive immune response-CD8(+) T cells that clear viral infections-are present in increased numbers in the lungs of patients with COPD, but they fail to protect against infection and may contribute to the immunopathology of the disease.

OBJECTIVES

CD8(+) function and signaling through the programmed cell death protein (PD)-1 exhaustion pathway were investigated as a potential key mechanism of viral exacerbation of the COPD lung.

METHODS

Tissue from control subjects and patients with COPD undergoing lung resection was infected with live influenza virus ex vivo. Viral infection and expression of lung cell markers were analyzed using flow cytometry.

MEASUREMENTS AND MAIN RESULTS

The proportion of lung CD8(+) T cells expressing PD-1 was greater in COPD (mean, 16.2%) than in controls (4.4%, P = 0.029). Only epithelial cells and macrophages were infected with influenza, and there was no difference in the proportion of infected cells between controls and COPD. Infection up-regulated T-cell PD-1 expression in control and COPD samples. Concurrently, influenza significantly up-regulated the marker of cytotoxic degranulation (CD107a) on CD8(+) T cells (P = 0.03) from control subjects but not on those from patients with COPD. Virus-induced expression of the ligand PD-L1 was decreased on COPD macrophages (P = 0.04) with a corresponding increase in IFN-γ release from infected COPD explants compared with controls (P = 0.04).

CONCLUSIONS

This study has established a signal of cytotoxic immune dysfunction and aberrant immune regulation in the COPD lung that may explain both the susceptibility to viral infection and the excessive inflammation associated with exacerbations.

Understanding persistent bacterial lung infections: clinical implications informed by the biology of the microbiota and biofilms

The infections found in chronic obstructive pulmonary disease, cystic fibrosis, and bronchiectasis share a number of clinical similarities, the most striking of which is bacterial persistence despite the use of antibiotics. These infections have been clinically described using culture-based methods usually performed on sputum samples, and treatment has been directed towards the bacteria found in this manner. Unfortunately the clinical response to antibiotics is frequently not predictable based on these cultures, and the role of these cultured organisms in disease progression has been debated. The past 20 years have seen a revolution in the techniques used to describe bacterial populations and their growth patterns. These techniques have revealed these persistent lung infections are vastly more complicated than described by traditional, and still widely relied upon, sputum cultures. A better understanding of the initiation and evolution of these infections, and better clinical tools to describe them, will dramatically alter the way patients are cared for. While clinical tests to more accurately describe these infections are not yet available, the better appreciation of these infections afforded by current science should enlighten practitioners as to the care of their patients with these diseases.

Bacterial-viral load and the immune response in stable and exacerbated COPD: significance and therapeutic prospects

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation and an abnormal inflammatory response of the lung. Bacteria and viruses are a major cause of COPD exacerbations and may contribute to COPD progression by perpetuating the inflammatory response in the airways. Bacterial variety diminishes with increasing COPD severity. Respiratory viruses can colonize the lower respiratory tract in stable COPD, altering the respiratory microbiome and facilitating secondary bacterial infections. In this review, we present the most updated information about the role of bacteria and viruses in stable and exacerbated COPD. In our opinion, to optimize therapeutic strategies, the dynamic events involving bacterial-viral infections and related immune response in COPD phenotypes need to be better clarified. Our paper would address these points that we consider of great importance for the clinical management of COPD.

COPD is characterized by increased detection of Haemophilus influenzae, Streptococcus pneumoniae and a deficiency of Bacillus species

BACKGROUND AND OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is characterized by progressive airflow limitation and inflammation. Airway bacterial colonization is increased in COPD; however, the role of potentially pathogenic and non-pathogenic bacteria in the pathogenesis of disease is unclear. This study characterized the presence of bacteria in a well-characterized cohort of adults with COPD and healthy controls.

METHODS

Adults with COPD (n = 70) and healthy controls (n = 51) underwent clinical assessment and sputum induction. Sputum was dispersed, and total and differential cell counts were performed. Bacteria were cultured, identified and enumerated. Supernatants were assessed for neutrophil elastase (NE) and IL-1β. Common respiratory pathogens were also determined using real-time PCR.

RESULTS

Participants with COPD had a typical neutrophilic inflammatory profile. The total load of bacteria was increased in COPD and was associated with poorer respiratory health status, as measured by the St George's Respiratory Questionnaire (Spearman's r = 0.336, P = 0.013). Significantly lower levels of culturable Bacillus species were identified compared with healthy controls. PCR analyses revealed increased rates of detection of potentially pathogenic bacteria with Haemophilus influenzae detection associated with higher sputum levels of NE and IL-1β, while Streptococcus pneumoniae was more common in male ex-smokers with emphysema and a deficit in diffusion capacity.

CONCLUSION

Non-pathogenic and pathogenic bacteria were altered in the sputum of patients with COPD. These observations highlight the potential to identify treatment and management strategies that both target specific bacterial pathogens and restore the microbial balance, which may lead to reductions in inflammation and subsequent improvements in lung health.

Pulmonary Artery Enlargement Is Associated With Cardiac Injury During Severe Exacerbations of COPD

BACKGROUND

Relative pulmonary arterial enlargement, defined by a pulmonary artery to aorta (PA/A) ratio > 1 on CT scanning, predicts hospitalization for acute exacerbations of COPD (AECOPD). However, it is unclear how AECOPD affect the PA/A ratio. We hypothesized that the PA/A ratio would increase at the time of AECOPD and that a ratio > 1 would be associated with worse clinical outcomes.

METHODS

Patients discharged with an International Classification of Diseases, Ninth Revision, diagnosis of AECOPD from a single center over a 5-year period were identified. Patients were included who had a CT scan performed during the stable period prior to the index AECOPD episode as well as a CT scan at the time of hospitalization. A subset of patients also underwent postexacerbation CT scans. The pulmonary arterial diameter, ascending aortic diameter, and the PA/A ratio were measured on CT scans. Demographic data, comorbidities, troponin level, and hospital outcome data were analyzed.

RESULTS

A total of 134 patients were included in the study. They had a mean age of 65 ± 10 years, 47% were male, and 69% were white; overall, patients had a mean FEV1 of 47% ± 19%. The PA/A ratio increased from baseline at the time of exacerbation (0.97 ± 0.15 from 0.91 ± 0.17; P < .001). Younger age and known pulmonary hypertension were independently associated with an exacerbation PA/A ratio > 1. Patients with PA/A ratio > 1 had higher troponin values. Those with a PA/A ratio > 1 and troponin levels > 0.01 ng/mL had increased acute respiratory failure, ICU admission, or inpatient mortality compared with those without both factors (P = .0028). The PA/A ratio returned to baseline values following AECOPD.

CONCLUSIONS

The PA/A ratio increased at the time of severe AECOPD and a ratio > 1 predicted cardiac injury and a more severe hospital course.

Safety and Tolerability of Nebulized Amoxicillin-Clavulanic Acid in Patients with COPD (STONAC 1 and STONAC 2)

The safety and tolerability of nebulized amoxicillin clavulanic acid were determined in patients with stable COPD and during severe exacerbations of COPD. Nine stable COPD patients received doses ranging from 50:10 mg up to 300:60 mg amoxicillin clavulanic acid and eight patients hospitalised for a COPD exacerbation received fixed doses 200/40 mg twice daily. Safety was evaluated by spirometry before and after inhalation. Tolerability was evaluated by questionnaire. Plasma and expectorated sputum samples were assayed for amoxicillin content. Seventeen patients underwent in total 100 nebulizations with amoxicillin clavulanic acid. In this safety and tolerability study no clinically relevant deteriorations in FEV1 were observed. Nebulized amoxicillin clavulanic acid produces sputum concentrations well above the Minimal Inhibiting Concentration of 90% for potential pathogenic micro-organisms, with low concentrations in the central compartment (low systemic exposure). Based on spirometry and reported side effects, inhalation of nebulized amoxicillin clavulanic acid seems to be safe and well tolerated, both in stable patients with COPD as in those experiencing a severe exacerbation. Levels of amoxicillin were adequate.

Osteopontin That Is Elevated in the Airways during COPD Impairs the Antibacterial Activity of Common Innate Antibiotics

Bacterial infections of the respiratory tract contribute to exacerbations and disease progression in chronic obstructive pulmonary disease (COPD). There is also an increased risk of invasive pneumococcal disease in COPD. The underlying mechanisms are not fully understood but include impaired mucociliary clearance and structural remodeling of the airways. In addition, antimicrobial proteins that are constitutively expressed or induced during inflammatory conditions are an important part of the airway innate host defense. In the present study, we show that osteopontin (OPN), a multifunctional glycoprotein that is highly upregulated in the airways of COPD patients co-localizes with several antimicrobial proteins expressed in the airways. In vitro, OPN bound lactoferrin, secretory leukocyte peptidase inhibitor (SLPI), midkine, human beta defensin-3 (hBD-3), and thymic stromal lymphopoietin (TSLP) but showed low or no affinity for lysozyme and LL-37. Binding of OPN impaired the antibacterial activity against the important bacterial pathogens Streptococcus pneumoniae and Pseudomonas aeruginosa. Interestingly, OPN reduced lysozyme-induced killing of S. pneumoniae, a finding that could be explained by binding of OPN to the bacterial surface, thereby shielding the bacteria. A fragment of OPN generated by elastase of P. aeruginosa retained some inhibitory effect. Some antimicrobial proteins have additional functions. However, the muramidase-activity of lysozyme and the protease inhibitory function of SLPI were not affected by OPN. Taken together, OPN can contribute to the impairment of innate host defense by interfering with the function of antimicrobial proteins, thus increasing the vulnerability to acquire infections during COPD.

Comparative Analyses of the Lipooligosaccharides from Nontypeable Haemophilus influenzae and Haemophilus haemolyticus Show Differences in Sialic Acid and Phosphorylcholine Modifications

Haemophilus haemolyticus and nontypeable Haemophilus influenzae (NTHi) are closely related upper airway commensal bacteria that are difficult to distinguish phenotypically. NTHi causes upper and lower airway tract infections in individuals with compromised airways, while H. haemolyticus rarely causes such infections. The lipooligosaccharide (LOS) is an outer membrane component of both species and plays a role in NTHi pathogenesis. In this study, comparative analyses of the LOS structures and corresponding biosynthesis genes were performed. Mass spectrometric and immunochemical analyses showed that NTHi LOS contained terminal sialic acid more frequently and to a higher extent than H. haemolyticus LOS did. Genomic analyses of 10 strains demonstrated that H. haemolyticus lacked the sialyltransferase genes lic3A and lic3B (9/10) and siaA (10/10), but all strains contained the sialic acid uptake genes siaP and siaT (10/10). However, isothermal titration calorimetry analyses of SiaP from two H. haemolyticus strains showed a 3.4- to 7.3-fold lower affinity for sialic acid compared to that of NTHi SiaP. Additionally, mass spectrometric and immunochemical analyses showed that the LOS from H. haemolyticus contained phosphorylcholine (ChoP) less frequently than the LOS from NTHi strains. These differences observed in the levels of sialic acid and ChoP incorporation in the LOS structures from H. haemolyticus and NTHi may explain some of the differences in their propensities to cause disease.

Toward antiviral therapy/prophylaxis for rhinovirus-induced exacerbations of chronic obstructive pulmonary disease: challenges, opportunities, and strategies

Chronic obstructive pulmonary disease (COPD) is a life-threatening lung illness characterized by persistent and progressive airflow limitation. Exacerbations of COPD contribute to the severity of this pathology and accelerate disease progression. To date, pharmacological treatment of both stable COPD patients and patients experiencing exacerbations is mainly symptomatic with bronchodilators and steroids as the mainstay of therapy. Bacteria trigger such exacerbations in a number of cases; hence, antibiotics might be included in the treatment as well. Several respiratory viruses are frequently detected in sputum from patients during COPD exacerbations. These include influenza viruses, respiratory syncytial virus, and, most often, rhinoviruses. In this review, we discuss the potential use of an anti-rhinovirus drug for the treatment and prophylaxis of rhinovirus-induced COPD exacerbations and the path forward toward the development and use of such a drug. Copyright © 2015 John Wiley & Sons, Ltd.

Pseudomonas aeruginosa stimulates tyrosine phosphorylation of and TLR5 association with the MUC1 cytoplasmic tail through EGFR activation

BACKGROUND

MUC1 is a membrane-tethered mucin expressed on the surface of epithelial and hematopoietic cells. Previous studies have established that MUC1 attenuates airway inflammation in response to Pseudomonas aeruginosa (Pa) through suppression of Toll-like receptor (TLR) signaling. Here, we elucidate the mechanism through which the MUC1 cytoplasmic tail (CT) inhibits TLR5 signaling in response to Pa and its flagellin in primary normal human bronchial epithelial (NHBE) cells.

METHODS

NHBE and human and mouse macrophages were stimulated with Pa or flagellin and transforming growth factor-α (TGF-α) and tumor necrosis factor-α (TNF-α) levels in cell culture supernatants were measured by ELISA. NHBE cells were stimulated with Pa, flagellin, or TNF-α and MUC1-CT, and epidermal growth factor receptor (EGFR) levels were measured by immunoblotting. NHBE cells were stimulated with Pa and MUC1-CT/TLR5 and MUC1-CT/EGFR association were detected by co-immunoprecipitation.

RESULTS

Stimulation of NHBE cells with Pa and flagellin each increased release of the EGFR ligand, TGF-α, from NHBE cells. Both stimuli also activated EGFR tyrosine phosphorylation in these same cells. By contrast, stimulation of NHBE cells with Pa failed to induce TNF-α release, whereas stimulation of human or mouse macrophages with Pa promoted TNF-α release. Stimulation of NHBE cells with recombinant TNF-α increased both MUC1 and EGFR protein levels, and stimulation of these cells with Pa enhanced MUC1-CT tyrosine phosphorylation and increased MUC1-CT/TLR5 and MUC1-CT/EGFR protein association, in an EGFR-dependent manner.

CONCLUSIONS

These results indicate that in response to Pa or flagellin, EGFR associates with and tyrosine phosphorylates MUC1-CT in primary NHBE cells, leading to increased MUC1-CT association with TLR5. Based on prior studies in tumor cells, increased MUC1-CT/TLR5 association in NHBE cells is predicted to competitively inhibit Pa/flagellin-stimulated TLR5 activation, reduce TLR5-dependent cell signaling, and down-regulate airway inflammation. Given that MUC1 is a universal suppressor of TLR signaling, the results from this study suggest that abnormal interactions between MUC1 and EGFR or TLRs may lead to the development of chronic inflammatory diseases. Thus, this is an important finding from the clinical point of view.

Haemophilus influenzae induces steroid-resistant inflammatory responses in COPD

Background

Chronic obstructive pulmonary disease (COPD) is an inflammatory disorder partially resistant to glucocorticoids. A reduced histone deacetylase (HDAC) activity has been proposed to explain this resistance. Haemophilus influenzae frequently colonizes the airways of COPD patients, where it enhances inflammation. The effects of Haemophilus influenzae on HDAC activity have not been investigated before.

Methods

The effects of the presence or absence of Haemophilus influenzae ex-vivo and in vitro were studied. To this end, we determined: (1) cytokine release in alveolar macrophages (AM) from 7 patients with COPD, 5 healthy smokers, 6 healthy non-smokers and (2) HDAC activity, nuclear factor kappa B (NF-κB) activation in a macrophage-like cell line (PMA-transformed U937 cells) co-cultured with epithelial cells. Experiments were repeated with dexamethasone (1 μM) and/or the HDAC enhancer theophylline (10 μM).

Results

Haemophilus influenzae induced a steroid-resistant inflammatory response in AM from COPD and controls and decreased HDAC activity, activated NF-κB and induced the secretion of several cytokines (IL-6, IL-8, IL-1β, IL-10 and TNF-α) (p < 0.001 for all comparisons) in the macrophage-like cell line. Dexamethasone reduced NF-κB activation but it did not modify HDAC activity. The addition of theophylline to dexamethasone increased HDAC activity and suppressed cytokine release completely, without modifying NF-κB activation.

Conclusions

These results indicate that Haemophilus influenzae reduces HDAC activity and induces a NF-κB mediated inflammatory response that is only partially suppressed by glucocorticoids irrespective of having COPD. Yet, the latter can be fully restored by targeting HDAC activity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0155-3) contains supplementary material, which is available to authorized users.

Host-microbe interactions in distal airways: relevance to chronic airway diseases

This article is the summary of a workshop, which took place in November 2013, on the roles of microorganisms in chronic respiratory diseases. Until recently, it was assumed that lower airways were sterile in healthy individuals. However, it has long been acknowledged that microorganisms could be identified in distal airway secretions from patients with various respiratory diseases, including cystic fibrosis (CF) and non-CF bronchiectasis, chronic obstructive pulmonary disease, asthma and other chronic airway diseases (e.g. post-transplantation bronchiolitis obliterans). These microorganisms were sometimes considered as infectious agents that triggered host immune responses and contributed to disease onset and/or progression; alternatively, microorganisms were often considered as colonisers, which were considered unlikely to play roles in disease pathophysiology. These concepts were developed at a time when the identification of microorganisms relied on culture-based methods. Importantly, the majority of microorganisms cannot be cultured using conventional methods, and the use of novel culture-independent methods that rely on the identification of microorganism genomes has revealed that healthy distal airways display a complex flora called the airway microbiota. The present article reviews some aspects of current literature on host–microbe (mostly bacteria and viruses) interactions in healthy and diseased airways, with a special focus on distal airways.

Understanding host–microbe interactions in distal airways may lead to novel therapies for chronic airway diseaseshttp://ow.ly/HfENz

A review of the role of Haemophilus influenzae in community-acquired pneumonia

In an era when Haemophilus influenzae type b (Hib) conjugate vaccine is widely used, the incidence of Hib as a cause of community-acquired pneumonia (CAP) has dramatcally declined. Non-typeable H. influenzae (NTHi) strains and, occasionally, other encapsulated serotypes of H. influenzae are now the cause of the majority of invasive H. influenzae infectons, including bacteraemic CAP. NTHi have long been recognised as an important cause of lower respiratory tract infecton, including pneumonia, in adults, especially those with underlying diseases. The role of NTHi as a cause of non-bacteraemic CAP in children is less clear. In this review the evidence for the role of NTHi and capsulated strains of H. influenzae will be examined.

Pneumococcal Infection Aggravates Elastase-Induced Emphysema via Matrix Metalloproteinase 12 Overexpression

BACKGROUND

Acute exacerbation of chronic obstructive pulmonary disease (COPD)--typically caused by bacterial or viral infection--is associated with poor prognosis and emphysema progression through unknown mechanisms. We aimed to elucidate the mechanisms responsible for the poor prognosis and emphysema progression associated with COPD exacerbation.

METHODS

We established a mouse model mimicking acute human COPD exacerbation, wherein mice with elastase-induced emphysema were intranasally infected with Streptococcus pneumoniae.

RESULTS

In mice with elastase-induced emphysema, infection with S. pneumoniae resulted in increased mortality, an increased number of inflammatory cells in bronchoalveolar lavage fluid (BALF), and increased matrix metalloproteinase 12 (MMP-12) production in the lungs, as well as enhanced emphysema progression. The increased MMP-12 production was mostly due to alveolar type II cells, alveolar macrophages, and lymphocytes that aggregated around vessels and bronchioles. Dexamethasone treatment suppressed the mortality rate and number of inflammatory cells in BALF but not emphysema progression, possibly owing to the failure of MMP-12 suppression in the lungs, whereas treatment with the MMP inhibitor ONO-4817 dramatically suppressed both mortality rate and emphysema progression.

CONCLUSIONS

These results suggest that MMP-12 production during COPD exacerbation results in increased mortality and emphysema progression. Our study identifies MMP-12 as a target to prevent further aggravation of COPD.

Immune Dysfunction in Patients with Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a complex chronic disease. Chronic inflammation is the hallmark of COPD, involving the interplay of a wide variety of cells in the lung microenvironment. Cigarette smoke (CS) induces chronic lung inflammation and is considered a key etiological factor in the development and pathogenesis of COPD. Structural and inflammatory cells in the lung respond to CS exposure by releasing proinflammatory mediators that recruit additional inflammatory immune cells, which collectively contribute to the establishment of a chronic inflammatory microenvironment. Chronic inflammation contributes to lung damage, compromises innate and adaptive immune responses, and facilitates the recurrent episodes of respiratory infection that punctuate and further contribute to the pathological manifestations of the stable disease. A number of studies support the conclusion that immune dysfunction leads to exacerbations and disease severity in COPD. Our group has clearly demonstrated that CS exacerbates lung inflammation and compromises immunity to respiratory pathogens in a mouse model of COPD. We have also investigated the phenotype of immune cells in patients with COPD compared with healthy control subjects and found extensive immune dysfunction due to the presence and functional activity of T regulatory cells, CD4(+)PD-1(+) exhausted effector T cells and myeloid-derived suppressor cells. Manipulation of these immunosuppressive networks in COPD could provide a rational strategy to restore functional immune responses, reduce exacerbations, and improve lung function. In this review, we discuss the role of immune dysfunction in COPD that may contribute to recurrent respiratory infections and disease severity.

IL-17A and the Promotion of Neutrophilia in Acute Exacerbation of Chronic Obstructive Pulmonary Disease

RATIONALE

Nontypeable Haemophilus influenzae (NTHi) causes acute exacerbation of chronic obstructive pulmonary disease (AECOPD). IL-17A is central for neutrophilic inflammation and has been linked to COPD pathogenesis.

OBJECTIVES

We investigated whether IL-17A is elevated in NTHi-associated AECOPD and required for NTHi-exacerbated pulmonary neutrophilia induced by cigarette smoke.

METHODS

Experimental studies with cigarette smoke and NTHi infection were pursued in gene-targeted mice and using antibody intervention. IL-17A was measured in sputum collected from patients with COPD at baseline, during, and after AECOPD.

MEASUREMENTS AND MAIN RESULTS

Exacerbated airway neutrophilia in cigarette smoke-exposed mice infected with NTHi was associated with an induction of IL-17A. In agreement, elevated IL-17A was observed in sputum collected during NTHi-associated AECOPD, compared with samples collected before or after the event. NTHi-exacerbated neutrophilia and induction of neutrophil chemoattractants over the background of cigarette smoke, as observed in wild-type mice, was absent in Il17a(-/-) mice and in mice treated with a neutralizing anti-IL-17A antibody. Further studies revealed that IL-1 receptor (R)1 signaling was required for IL-17A-dependent neutrophilia. Moreover, deficiency or therapeutic neutralization of IL-17A did not increase bacterial burden or delay bacterial clearance.

CONCLUSIONS

IL-17A is induced during NTHi-associated AECOPD. Functionally, IL-1R1-dependent IL-17A is required for NTHi-exacerbated pulmonary neutrophilia induced by cigarette smoke. Targeting IL-17A in AECOPD may thus be beneficial to reduce neutrophil recruitment to the airways.

Host Response to the Lung Microbiome in Chronic Obstructive Pulmonary Disease

RATIONALE

The relatively sparse but diverse microbiome in human lungs may become less diverse in chronic obstructive pulmonary disease (COPD). This article examines the relationship of this microbiome to emphysematous tissue destruction, number of terminal bronchioles, infiltrating inflammatory cells, and host gene expression.

METHODS

Culture-independent pyrosequencing microbiome analysis was used to examine the V3-V5 regions of bacterial 16S ribosomal DNA in 40 samples of lung from 5 patients with COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage 4) and 28 samples from 4 donors (controls). A second protocol based on the V1-V3 regions was used to verify the bacterial microbiome results. Within lung tissue samples the microbiome was compared with results of micro-computed tomography, infiltrating inflammatory cells measured by quantitative histology, and host gene expression.

MEASUREMENTS AND MAIN RESULTS

Ten operational taxonomic units (OTUs) was found sufficient to discriminate between control and GOLD stage 4 lung tissue, which included known pathogens such as Haemophilus influenzae. We also observed a decline in microbial diversity that was associated with emphysematous destruction, remodeling of the bronchiolar and alveolar tissue, and the infiltration of the tissue by CD4(+) T cells. Specific OTUs were also associated with neutrophils, eosinophils, and B-cell infiltration (P < 0.05). The expression profiles of 859 genes and 235 genes were associated with either enrichment or reductions of Firmicutes and Proteobacteria, respectively, at a false discovery rate cutoff of less than 0.1.

CONCLUSIONS

These results support the hypothesis that there is a host immune response to microorganisms within the lung microbiome that appears to contribute to the pathogenesis of COPD.

Fine particulate matter in acute exacerbation of COPD

Chronic obstructive pulmonary disease (COPD) is a common airway disorder. In particular, acute exacerbations of COPD (AECOPD) can significantly reduce pulmonary function. The majority of AECOPD episodes are attributed to infections, although environmental stress also plays a role. Increasing urbanization and associated air pollution, especially in developing countries, have been shown to contribute to COPD pathogenesis. Elevated levels of particulate matter (PM) in polluted air are strongly correlated with the onset and development of various respiratory diseases. In this review, we have conducted an extensive literature search of recent studies of the role of PM_2.5 (fine PM) in AECOPD. PM_2.5 leads to AECOPD via inflammation, oxidative stress (OS), immune dysfunction, and altered airway epithelial structure and microbiome. Reducing PM_2.5 levels is a viable approach to lower AECOPD incidence, attenuate COPD progression and decrease the associated healthcare burden.

Targeting immune pathways for therapy in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are highly prevalent chronic inflammatory diseases of the airways, with differences in etiology, pathogenesis, immunologic mechanisms, clinical presentation, comorbidities, prognosis, and response to treatment. In mild to moderate early-onset allergic asthma, the Th2-driven eosinophilic airway inflammation and the ensuing disease can be well controlled with maintenance treatment with inhaled corticosteroids (ICS). In real-life settings, asthma control can be improved by facilitating adherence to ICS treatment and by optimizing inhaler technique. In patients with uncontrolled severe asthma, old and novel therapies targeting specific immunologic pathways should be added according to the underlying endotype/phenotype. In COPD, there is a high unmet need for safe and effective antiinflammatory treatments that not only prevent exacerbations but also have a beneficial impact on the course of the disease and improve survival. Although several new approaches aim to target the chronic neutrophilic pulmonary inflammation per se in patients with COPD, strategies that target the underlying causes of the pulmonary neutrophilia (e.g., smoking, chronic infection, and oxidative stress) might be more successful. In both chronic airway diseases (especially in more difficult, complex cases), the choice of the optimal treatment should be based not only on arbitrary clinical labels but also on the underlying immunopathology.

Inflammation in chronic obstructive pulmonary disease and its role in cardiovascular disease and lung cancer

Chronic obstructive pulmonary disease (COPD) is characterized by lung inflammation that persists after smoking cessation. This inflammation is heterogeneous but the key inflammatory cell types involved are macrophages, neutrophils and T cells. Other lung cells may also produce inflammatory mediators, particularly the epithelial cells. The main inflammatory mediators include tumor necrosis factor alpha, interleukin-1, interleukin-6, reactive oxygen species and proteases. COPD is also associated with systemic inflammation and there is a markedly increased risk of cardiovascular disease (particularly coronary artery disease) and lung cancer in patients with COPD. There is strong associative evidence that the inflammatory cells/mediators in COPD are also relevant to the development of cardiovascular disease and lung cancer. There are a large number of potential inhibitors of inflammation in COPD that may well have beneficial effects for these comorbidities. This is a not well-understood area and there is a requirement for more definitive clinical and mechanistic studies to define the relationship between the inflammatory process of COPD and cardiovascular disease and lung cancer.

HIV Infection Is Associated With Increased Risk for Acute Exacerbation of COPD

BACKGROUND

Poorly controlled HIV infection is associated with increased risk for chronic obstructive pulmonary disease (COPD). Acute exacerbations of COPD (AECOPD) are major contributors to morbidity and mortality. Little is known about the association between HIV infection and AECOPD.

METHODS

We identified 167 individuals with spirometry-confirmed COPD from a longitudinal study of current or former injection drug users at risk or with HIV infection. AECOPD, defined as self-report of worsening breathing requiring treatment with antibiotics or steroids, was assessed at 6-month study visits. Multivariable logistic regression identified factors associated with AECOPD.

RESULTS

Of 167 participants, the mean age was 52 years; 89% were black, 30% female, and 32% HIV infected (median CD4 count: 312 cells per milliliter, 46% with detectable HIV RNA). After adjusting for age, gender, smoking history, comorbidity treatment, and airflow obstruction severity, HIV was independently associated with a 2.47 increased odds of AECOPD [95% confidence interval (CI): 1.22 to 5.00]. Compared with HIV-uninfected persons, HIV-infected persons with undetectable (<50 copies/mL) HIV RNA levels and those with a CD4 count ≥350 cells per cubic millimeter demonstrated increased AECOPD (odds ratio, 2.91; 95% CI: 1.26 to 6.71; odds ratio, 4.16; 95% CI: 1.87 to 9.27, respectively). Higher AECOPD risk was observed with higher CD4 counts irrespective of treatment for comorbid diseases.

CONCLUSIONS

HIV infection is independently associated with increased odds of AECOPD, potentially due to differences in treatment access and to variable disease manifestation by immune status. Providers should be aware that HIV infection may increase risk for AECOPD and that symptom may be more discernible with intact immune function.

Effects of different antibiotic classes on airway bacteria in stable COPD using culture and molecular techniques: a randomised controlled trial

Background

Long-term antibiotic therapy is used to prevent exacerbations of COPD but there is uncertainty over whether this reduces airway bacteria. The optimum antibiotic choice remains unknown. We conducted an exploratory trial in stable patients with COPD comparing three antibiotic regimens against placebo.

Methods

This was a single-centre, single-blind, randomised placebo-controlled trial. Patients aged ≥45 years with COPD, FEV₁<80% predicted and chronic productive cough were randomised to receive either moxifloxacin 400 mg daily for 5 days every 4 weeks, doxycycline 100 mg/day, azithromycin 250 mg 3 times a week or one placebo tablet daily for 13 weeks. The primary outcome was the change in total cultured bacterial load in sputum from baseline; secondary outcomes included bacterial load by 16S quantitative PCR (qPCR), sputum inflammation and antibiotic resistance.

Results

99 patients were randomised; 86 completed follow-up, were able to expectorate sputum and were analysed. After adjustment, there was a non-significant reduction in bacterial load of 0.42 log₁₀ cfu/mL (95% CI −0.08 to 0.91, p=0.10) with moxifloxacin, 0.11 (−0.33 to 0.55, p=0.62) with doxycycline and 0.08 (−0.38 to 0.54, p=0.73) with azithromycin from placebo, respectively. There were also no significant changes in bacterial load measured by 16S qPCR or in airway inflammation. More treatment-related adverse events occurred with moxifloxacin. Of note, mean inhibitory concentrations of cultured isolates increased by at least three times over placebo in all treatment arms.

Conclusions

Total airway bacterial load did not decrease significantly after 3 months of antibiotic therapy. Large increases in antibiotic resistance were seen in all treatment groups and this has important implications for future studies.

Trial registration number

clinicaltrials.gov (NCT01398072).

Heterogeneity of chronic obstructive pulmonary disease exacerbations: a two-axes classification proposal

Exacerbations of chronic obstructive pulmonary disease (COPD) are clinically relevant events with therapeutic and prognostic implications. Yet, they are heterogeneous and can need different therapeutic strategies. In this Viewpoint, we propose an admittedly crude approach to a COPD exacerbation classification that might eventually help to define the most appropriate pharmacological treatment and clinical treatment setting for these patients. Our suggestion is to combine a pathobiological axis (biomarkers) to guide treatment decisions (use of antibiotics, steroids, or both) with a clinical axis (severity score) to decide the organisational context in which to optimally treat the patient. Needless to say, this proposal needs to be researched and eventually validated, refined, or disproved, but we hope that this process will contribute to the improvement of personalised treatment for patients with COPD exacerbations.

Multicentre investigation of pathogenic bacteria and antibiotic resistance genes in Chinese patients with acute exacerbation of chronic obstructive pulmonary disease

OBJECTIVE

A prospective observational study to investigate the distribution and antimicrobial resistance of pathogenic bacteria in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in Beijing, China.

METHODS

Patients with AECOPD were recruited from 11 general hospitals. Sputum specimens were cultured and bacteria identified. Antibiotic susceptibility was determined for each isolate, and presence of antibiotic resistance genes was evaluated using polymerase chain reaction.

RESULTS

Pathogenic bacteria were isolated from 109/318 patients (34.28%); 124 isolates of 22 pathogenic bacterial species were identified, including Klebsiella pneumoniae (16.94%), Pseudomonas aeruginosa (16.94%), Acinetobacter baumannii (11.29%), Streptococcus pneumoniae (8.87%), and Staphylococcus aureus (7.26%). S. aureus was sensitive to tigecycline, teicoplanin, vancomycin and linezolid but resistant to penicillin and levofloxacin. K.pneumoniae, P. aeruginosa, A. baumannii and E. coli were susceptible to amikacin and cefoperazone.

CONCLUSIONS

K. pneumoniae and P. aeruginosa are the most common pathogenic bacteria in AECOPD cases in Beijing, China. Our antibiotic resistance findings may be helpful in selecting antibiotic therapy.

Sputum Bacterial and Fungal Dynamics during Exacerbations of Severe COPD

The changes in the microbial community structure during acute exacerbations of severe chronic obstructive pulmonary disease (COPD) in hospitalized patients remain largely uncharacterized. Therefore, further studies focused on the temporal dynamics and structure of sputum microbial communities during acute exacerbation of COPD (AECOPD) would still be necessary. In our study, the use of molecular microbiological techniques provided insight into both fungal and bacterial diversities in AECOPD patients during hospitalization. In particular, we examined the structure and varieties of lung microbial community in 6 patients with severe AECOPD by amplifying 16S rRNA V4 hyper-variable and internal transcribed spacer (ITS) DNA regions using barcoded primers and the Illumina sequencing platform. Sequence analysis showed 261 bacterial genera representing 20 distinct phyla, with an average number of genera per patient of >157, indicating high diversity. Acinetobacter, Prevotella, Neisseria, Rothia, Lactobacillus, Leptotrichia, Streptococcus, Veillonella, and Actinomyces were the most commonly identified genera, and the average total sequencing number per sputum sample was >10000 18S ITS sequences. The fungal population was typically dominated by Candia, Phialosimplex, Aspergillus, Penicillium, Cladosporium and Eutypella. Our findings highlight that COPD patients have personalized structures and varieties in sputum microbial community during hospitalization periods.

Virulence Factors of Pseudomonas aeruginosa Induce Both the Unfolded Protein and Integrated Stress Responses in Airway Epithelial Cells

Pseudomonas aeruginosa infection can be disastrous in chronic lung diseases such as cystic fibrosis and chronic obstructive pulmonary disease. Its toxic effects are largely mediated by secreted virulence factors including pyocyanin, elastase and alkaline protease (AprA). Efficient functioning of the endoplasmic reticulum (ER) is crucial for cell survival and appropriate immune responses, while an excess of unfolded proteins within the ER leads to “ER stress” and activation of the “unfolded protein response” (UPR). Bacterial infection and Toll-like receptor activation trigger the UPR most likely due to the increased demand for protein folding of inflammatory mediators. In this study, we show that cell-free conditioned medium of the PAO1 strain of P. aeruginosa, containing secreted virulence factors, induces ER stress in primary bronchial epithelial cells as evidenced by splicing of XBP1 mRNA and induction of CHOP, GRP78 and GADD34 expression. Most aspects of the ER stress response were dependent on TAK1 and p38 MAPK, except for the induction of GADD34 mRNA. Using various mutant strains and purified virulence factors, we identified pyocyanin and AprA as inducers of ER stress. However, the induction of GADD34 was mediated by an ER stress-independent integrated stress response (ISR) which was at least partly dependent on the iron-sensing eIF2α kinase HRI. Our data strongly suggest that this increased GADD34 expression served to protect against Pseudomonas-induced, iron-sensitive cell cytotoxicity. In summary, virulence factors from P. aeruginosa induce ER stress in airway epithelial cells and also trigger the ISR to improve cell survival of the host.

Pseudomonas aeruginosa causes a devastating infection when it affects patients with cystic fibrosis or other chronic lung diseases. It often causes chronic infection due to its resistance to antibiotic treatment and its ability to form biofilms in these patients. The toxic effects of P. aeruginosa are largely mediated by secreted virulence factors. Efficient functioning of the endoplasmic reticulum is crucial for cell survival and appropriate immune responses, while its dysfunction causes stress and activation of the unfolded protein response. In this study, we found that virulence factors secreted by P. aeruginosa trigger the unfolded protein response in human cells by causing endoplasmic reticulum stress. In addition, secreted virulence factors activate the integrated stress response via a parallel independent pathway. Both stress pathways lead to the induction of the protein GADD34, which appears to provide protection against the toxic effects of the secreted virulence factors.

The existence of bronchiectasis predicts worse prognosis in patients with COPD

Bronchiectasis is prevalent in patients with COPD. The objective of this study was to assess the clinical characteristics and prognostic value of bronchiectasis in patients with COPD in China. Data from patients diagnosed with COPD at the Shanghai Pulmonary Hospital between January 2009 and December 2013 were retrospectively collected and analyzed. SPSS statistical software was used to analyze the data. Data from 896 patients with COPD were analyzed. Bronchiectasis was present in 311 patients. The isolation of pseudomonas aeruginosa (PA) from sputum was the variable most significantly associated with the presence of bronchiectasis in patients with COPD (hazard ratio (HR), 2.93; 95% confidence interval (CI), 1.35–6.37; P = 0.007). During follow-up (median of 21 months; interquartile range: 10-39 months), there were 75 deaths, of which 39 were in the bronchiectasis group. The presence of bronchiectasis (HR, 1.77; 95% CI, 1.02–3.08; P = 0.043) was associated with an increase in all-cause mortality in patients with COPD. These results suggest that bronchiectasis in patients with COPD was associated with the isolation of PA from the sputum. Bronchiectasis was an independent risk factor for all-cause mortality in patients with COPD.

Efficacy and Safety of OM-85 in Patients with Chronic Bronchitis and/or Chronic Obstructive Pulmonary Disease

BACKGROUND

Recurrent acute exacerbations are generally associated with accelerated decline of lung function and characterized by reduced physical activity and worsening of clinical status in patients with chronic obstructive pulmonary disease (COPD). Effective practices and therapies aimed at preventing acute exacerbations are continuously under investigation by healthcare providers. This double-blind, placebo-control, randomized clinical trial sought to evaluate the preventive effect of a bacterial lysate (OM-85) on acute exacerbations in patients with COPD or chronic bronchitis in China.

METHODS

A total of 428 patients were randomly assigned either to OM-85 treatment or to placebo. Patients received study drug or placebo for 10 days per month over 3 consecutive months, with a 10-week follow-up. Three hundred and eighty-four (384) patients completed the study (192 in the OM-85 group and 192 in the placebo group) and were included in the full analysis set (FAS). Thirty (30) patients, 21 in the OM-85 and 9 in the placebo groups, were excluded due to protocol violations and drop-outs, and the remaining 354 patients (171 in the OM-85 and 183 in the placebo groups) were included in the per protocol set (PPS).

RESULTS

The proportion of patients with recurrent acute exacerbations in the OM-85 group was significantly lower than in the placebo group at the end of the treatment period, both, in the FAS (23.4 % vs. 33.3 %, p = 0.0311) and in the PPS (17.0 % vs. 31.2 %, p < 0.05). Throughout the entire 22-week study period, the proportion of patients with recurrent acute exacerbations in the OM-85 group was lower than in the placebo group in the FAS (32.8 % vs. 38.0 %, p = 0.277), while the difference is statistically significant in the PPS (26.3 % vs. 36.1 %, p < 0.05).

CONCLUSION

OM-85 significantly reduced the proportion of patients with acute exacerbation after 12 weeks of therapy and the benefit appeared to be maintained up to 22 weeks, and showed a favorable tolerability profile.

Moraxella catarrhalis induces an immune response in the murine lung that is independent of human CEACAM5 expression and long-term smoke exposure

In patients with chronic obstructive pulmonary disease (COPD), Moraxella catarrhalis infection of the lower airways is associated with chronic colonization and inflammation during stable disease and acute exacerbations. Chronic smoke exposure induces chronic inflammation and impairs mucociliary clearance, thus contributing to bacterial colonization of the lower airways in COPD patients. The human-specific carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 5, expressed in human airways, has been shown to contribute to epithelial colonization of CEACAM-binding pathogens. To investigate the impact of CEACAM5 expression on pulmonary M. catarrhalis colonization, we infected mice transgenic for human CEACAM5 (hCEACAM5) and wild type mice intratracheally with M. catarrhalis with or without preceding smoke exposure and analyzed bacterial colonization and local and systemic inflammation. Our results show that airway infection with M. catarrhalis accelerated acute local but not systemic inflammation, albeit independent of hCEACAM5 expression. Long-term smoke exposure alone or prior to M. catarrhalis infection did not contribute to increased local or systemic inflammation. No difference was found in pulmonary clearance of M. catarrhalis in hCEACAM5-transgenic mice compared with wild-type mice. Smoke exposure neither altered time nor extent of persistence of M. catarrhalis in the lungs of both genotypes. In conclusion, M. catarrhalis induced a local acute immune response in murine airways. Neither hCEACAM5 expression nor chronic smoke exposure nor a combination of both was sufficient as prerequisites for the establishment of chronic M. catarrhalis colonization. Our results demonstrate the difficulties in mirroring conditions of chronic airways colonization of M. catarrhalis in a murine model.

The Lung Immune Response to Nontypeable Haemophilus influenzae (Lung Immunity to NTHi)

Haemophilus influenzae is divided into typeable or nontypeable strains based on the presence or absence of a polysaccharide capsule. The typeable strains (such as type b) are an important cause of systemic infection, whilst the nontypeable strains (designated as NTHi) are predominantly respiratory mucosal pathogens. NTHi is present as part of the normal microbiome in the nasopharynx, from where it may spread down to the lower respiratory tract. In this context it is no longer a commensal and becomes an important respiratory pathogen associated with a range of common conditions including bronchitis, bronchiectasis, pneumonia, and particularly chronic obstructive pulmonary disease. NTHi induces a strong inflammatory response in the respiratory tract with activation of immune responses, which often fail to clear the bacteria from the lung. This results in recurrent/persistent infection and chronic inflammation with consequent lung pathology. This review will summarise the current literature about the lung immune response to nontypeable Haemophilus influenzae, a topic that has important implications for patient management.

Expression of IgA Proteases by Haemophilus influenzae in the Respiratory Tract of Adults With Chronic Obstructive Pulmonary Disease

BACKGROUND

Immunoglobulin (Ig)A proteases of Haemophilus influenzae are highly specific endopeptidases that cleave the hinge region of human IgA1 and also mediate invasion and trafficking in human respiratory epithelial cells, facilitating persistence of H. influenzae. Little is known about the expression of IgA proteases in clinical settings of H. influenzae infection.

METHODS

We identified and characterized IgA protease genes in H. influenzae and studied their expression and proteolytic specificity, in vitro and in vivo in 169 independent strains of H. influenzae collected longitudinally over 10 years from adults with chronic obstructive pulmonary disease.

RESULTS

The H. influenzae pangenome has 2 alleles of IgA protease genes; all strains have igaA, and 40% of strains have igaB. Each allele has 2 variants with differing proteolytic specificities for human IgA1. A total of 88% of 169 strains express IgA protease activity. Expression of the 4 forms of IgA protease varies among strains. Based on the presence of IgA1 fragments in sputum samples, each of the different forms of IgA protease is selectively expressed in the human airways during infection.

CONCLUSIONS

Four variants of IgA proteases are variably expressed by H. influenzae during infection of the human airways.

Infections in "noninfectious" lung diseases

Many chronic pulmonary diseases, including those that are not primarily infectious in etiology, have some aspects of their pathogenesis that are influenced by infectious organisms. Microorganisms may contribute to chronic lung diseases, either directly (i.e., overt infection) or indirectly, via the amplification of inflammatory pathways that are critical to host defense. As techniques for detecting and characterizing microorganisms have advanced, investigations of both infecting and colonizing organisms have yielded new insights into mechanisms of pulmonary disease. In addition, changes in patterns of infection and microbial resistance have important implications for treatment. Examples of these infectious-pulmonary associations, including Haemophilus influenzae infection and chronic obstructive pulmonary disease, nontuberculous mycobacteria and bronchiectasis, and human immunodeficiency virus and obstructive lung disease, are reviewed.

Prevention of acute exacerbations of COPD: American College of Chest Physicians and Canadian Thoracic Society Guideline

BACKGROUND

COPD is a major cause of morbidity and mortality in the United States as well as throughout the rest of the world. An exacerbation of COPD (periodic escalations of symptoms of cough, dyspnea, and sputum production) is a major contributor to worsening lung function, impairment in quality of life, need for urgent care or hospitalization, and cost of care in COPD. Research conducted over the past decade has contributed much to our current understanding of the pathogenesis and treatment of COPD. Additionally, an evolving literature has accumulated about the prevention of acute exacerbations.

METHODS

In recognition of the importance of preventing exacerbations in patients with COPD, the American College of Chest Physicians (CHEST) and Canadian Thoracic Society (CTS) joint evidence-based guideline (AECOPD Guideline) was developed to provide a practical, clinically useful document to describe the current state of knowledge regarding the prevention of acute exacerbations according to major categories of prevention therapies. Three key clinical questions developed using the PICO (population, intervention, comparator, and outcome) format addressed the prevention of acute exacerbations of COPD: nonpharmacologic therapies, inhaled therapies, and oral therapies. We used recognized document evaluation tools to assess and choose the most appropriate studies and to extract meaningful data and grade the level of evidence to support the recommendations in each PICO question in a balanced and unbiased fashion.

RESULTS

The AECOPD Guideline is unique not only for its topic, the prevention of acute exacerbations of COPD, but also for the first-in-kind partnership between two of the largest thoracic societies in North America. The CHEST Guidelines Oversight Committee in partnership with the CTS COPD Clinical Assembly launched this project with the objective that a systematic review and critical evaluation of the published literature by clinical experts and researchers in the field of COPD would lead to a series of recommendations to assist clinicians in their management of the patient with COPD.

CONCLUSIONS

This guideline is unique because it provides an up-to-date, rigorous, evidence-based analysis of current randomized controlled trial data regarding the prevention of COPD exacerbations.

Prise en charge des exacerbations : de la ville à l’hôpital

La Société de pneumologie de langue française définie l’exacerbation aiguë de bronchopneumopathie chronique obstructive comme une majoration des symptômes respiratoires au-delà des variations quotidiennes (en pratique, d’une durée ≥ 48 h ou justifiant une modification thérapeutique).

La cause de ces exacerbations est principalement infectieuse : virale (rhinovirus, virus influenzae et parainfluenzae, coronavirus, adénovirus et virus respiratoire syncytial) ou bactérienne (principalement, Haemophilus influenzae, Streptococcus pneumoniae et Moraxella catarrhalis). Elles peuvent également résulter de l’exposition à certains polluants : NO₂, SO₂, ozone et pollution particulaire (PM10 et PM2,5). Elle reste indéterminée dans près de 30 % des cas.

Les diagnostics différentiels incluent les pneumopathies infectieuses, les pneumothorax, les poussées d’insuffisance cardiaque et les embolies pulmonaires.

La présence de signes de gravité conditionne l’hospitalisation : signes d’insuffisance respiratoire aiguë, de choc ou de défaillance neurologique, mais aussi en cas de patient fragile, d’absence de soutien familial à domicile ou de réponse au traitement initial.

Le traitement consiste en une majoration des bronchodilatateurs, une kinésithérapie respiratoire, une antibiothérapie en cas d’expectoration franchement purulente. La prescription de corticoïdes systémiques ne doit pas être systématique. La dose recommandée est de 0,5 mg/kg sur une courte période (5–7 jours). Lors d’une hospitalisation, une oxygénothérapie et une thromboprophylaxie peuvent être instaurées. La ventilation non invasive est principalement indiquée en cas de persistance d’une hypercapnie malgré un traitement médical optimal. Que le patient soit pris en charge en ambulatoire ou en hospitalisation, une réévaluation clinique à 48–72 h est indispensable.

A bibliometric analysis of the 100 most influential papers on COPD

OBJECTIVE

We aimed to identify the 100 top-cited articles published on chronic obstructive pulmonary disease (COPD) and to analyze their characteristics so as to provide information on the achievement and development in COPD research over the past decades.

METHODS AND MATERIALS

A comprehensive list of citation classics in COPD was generated by searching the Science Citation Index expanded database, using the keywords "COPD" or "chronic obstructive pulmonary disease" or "chronic obstructive pulmonary diseases". The 100 top-cited research papers were retrieved by reading the abstract or full text if needed. All eligible articles were read for basic information, including country of origin, organizations, article type, journals, research field, and authors.

RESULTS

The 100 top-cited articles on COPD were published between 1966 and 2010. The number of citations ranged from 254 to 2,164, with a mean of 450 citations for each article. These citation classics were from 32 countries, with 38 from the United States. The Imperial College London led the list of classics, with 16 papers. The 100 top-cited articles were distributed in 18 journals, with the American Journal of Respiratory, Critical Care Medicine, and Journal of the American Medical Association topping the list. Among the various fields, both respiratory system (63%) and general internal medicine (63%) were the most common fields of study for the 100 articles.

CONCLUSION

Our bibliometric analysis provides a historical perspective on the progress of scientific research on COPD. Articles originating from the United States and published in high-impact specialized respiratory journals are most likely to be cited in the field of COPD research.

Antibiotic treatment of severe exacerbations of chronic obstructive pulmonary disease with procalcitonin: a randomized noninferiority trial

Background

The duration of antibiotic treatment of exacerbations of COPD (ECOPD) is controversial. Serum procalcitonin (PCT) is a biomarker of bacterial infection used to identify the cause of ECOPD.

Methods and Findings

We investigated whether a PCT-guided plan would allow a shorter duration of antibiotic treatment in patients with severe ECOPD. For this multicenter, randomized, non-inferiority trial, we enrolled 184 patients hospitalized with ECOPD from 18 hospitals in Italy. Patients were assigned to receive antibiotics for 10 days (standard group) or for either 3 or 10 days (PCT group). The primary outcome was the rate of ECOPD at 6 months. Having planned to recruit 400 patients, we randomized only 183: 93 in the PCT group and 90 in the standard group. Thus, the completed study was underpowered. The ECOPD rate at 6 months between PCT-guided and standard antibiotic treatment was not significant (% difference, 4.04; 90% confidence interval [CI], −7.23 to 15.31), but the CI included the non-inferiority margin of 15. In the PCT-guided group, about 50% of patients were treated for 3 days, and there was no difference in primary or secondary outcomes compared to patients treated for 10 days.

Conclusions

Although the primary and secondary clinical outcomes were no different for patients treated for 3 or 10 days in the PCT group, the conclusion that antibiotics can be safely stopped after 3 days in patients with low serum PCT cannot be substantiated statistically. Thus, the results of this study are inconclusive regarding the noninferiority of the PCT-guided plan compared to the standard antibiotic treatment. The study was funded by Agenzia Italiana del Farmaco (AIFA-FARM58J2XH). Clinical trial registered with www.clinicaltrials.gov (NCT01125098).

Trial Registration

ClinicalTrials.gov NCT01125098

COPD: early diagnosis and treatment to slow disease progression

AIMS

Chronic obstructive pulmonary disease (COPD) is usually a progressive condition. Undiagnosed early-stage disease, particularly in symptomatic patients, is likely to become more severe with time. Hence, prevention or reduction in disease progression is highly relevant. We evaluated the published data and discussed the potential impact of early intervention on the course of COPD.

METHODS

We performed PubMed searches of studies in early or mild COPD, focusing on those relating to lung function decline.

RESULTS

Smoking cessation reduced lung function decline at all stages of COPD, and the earlier the intervention, the greater the impact on lung function. Accumulating data from placebo-controlled trials suggested that long-acting bronchodilators can slow the decline in lung function, as well as reduce exacerbation and mortality rates and improve health-related quality of life (HRQoL) in patients with mild-to-moderate COPD. Inhaled corticosteroids (ICS) do not impact lung function in early COPD, and further research is needed on the role of long-acting β2-agonist-ICS combination therapy in these patients.

CONCLUSIONS

Initiating treatment early in the course of COPD is likely to slow disease progression and improve HRQoL. Current data support maintenance treatment with a long-acting bronchodilator in this patient group. However, many questions remain unanswered regarding the optimal treatment of mild COPD, and further research is required to develop evidence-based recommendations in this field.

Difficult identification of Haemophilus influenzae, a typical cause of upper respiratory tract infections, in the microbiological diagnostic routine

Haemophilus influenzae is a key pathogen of upper respiratory tract infections. Its reliable discrimination from nonpathogenic Haemophilus spp. is necessary because merely colonizing bacteria are frequent at primarily unsterile sites. Due to close phylogenetic relationship, it is not easy to discriminate H. influenzae from the colonizer Haemophilus haemolyticus. The frequency of H. haemolyticus isolations depends on factors like sampling site, patient condition, and geographic region. Biochemical discrimination has been shown to be nonreliable. Multiplex PCR including marker genes like sodC, fucK, and hpd or sequencing of the 16S rRNA gene, the P6 gene, or multilocus-sequence-typing is more promising. For the diagnostic routine, such techniques are too expensive and laborious. If available, matrix-assisted laser-desorption-ionization time-of-flight mass spectrometry is a routine-compatible option and should be used in the first line. However, the used database should contain well-defined reference spectra, and the spectral difference between H. influenzae and H. haemolyticus is small. Fluorescence in-situ hybridization is an option for less well-equipped laboratories, but the available protocol will not lead to conclusive results in all instances. It can be used as a second line approach. Occasional ambiguous results have to be resolved by alternative molecular methods like 16S rRNA gene sequencing.

Combined exposure to bacteria and cigarette smoke resembles characteristic phenotypes of human COPD in a murine disease model

Abundant microbial colonization is a hallmark of COPD and smoke exposure likely increases the susceptibility to colonization and infection. The aim of the present study was to characterize the pulmonary changes of a combined exposure to cigarette smoke (CS) and microbial challenge in a preclinical murine COPD model. Animals were exposed to CS for 2 weeks, 3, and 6 months. Low and high doses of heat inactivated nontypeable Haemophilus influenzae (NTHi) were administered by inhalation during the whole exposure time. Pulmonary changes were analyzed by stereology, pulmonary function tests, measurements of inflammatory cells and mediators, and histopathology. Exposure of smoke in a relatively low concentration caused COPD-like changes of pulmonary function and only little inflammation. The coadministration of low dose NTHi (ld-NTHi) augmented a macrophage dominated inflammatory profile, while high dose NTHi (hd-NTHi) induced a neutrophilic inflammatory pattern. IL-17A secretion was solely dependent on the exposure to NTHi. Also goblet cell metaplasia and the formation of lymphoid aggregates depended on exposure to bacteria. In conclusion, the combination of exposure to smoke and bacterial compounds resulted in a mouse model that resembles several aspects of human disease. Exposure to microbial structural components appears necessary to model important pathologic features of the disease and the quantity of the exposure with microorganisms has a strong effect on the phenotype.

Viral Profile of COPD Exacerbations According to Patients

Background :

To compare the differences between elderly and non-elderly patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) due to viral infections.

Methods :

Patients with chronic obstructive pulmonary disease (COPD) exacerbation were recruited and classified as elderly (>65 years) and non-elderly (≤ 65 years). Sputum and oropharyngeal samples were assessed, PCR for respiratory viruses and cultures for common pathogens were performed.

Results :

247 patients (median age: 69.3±9.5 years) were recruited and categorized into group A: non-elderly patients [n=81 (32.8%), median age 58±5.99] and group B: elderly patients [n=166 (67.2%), median age 74.8±4.8] years. In 133 (53.8%) patients a viral infection was identified and in 34 (13.8%) a bacterial pathogen was isolated from cultures. In 18 (7.3%) patients a double infection (bacterial+viral) was identified. In group B, the presence of cardiac failure (46.6% vs 28.3%, p<0.001), renal failure (10.5% vs 4%, p=0.03), bacterial co-infection (13.8% vs 7.4%, p=0.04), influenza vaccination rates (45.5% vs 215, p<0.001), and longer hospital stay (8.4±4.4 vs 7.5±3.2 days, p=0.02) were higher than group A. The overall rate of viral infections did not differ according to age. A trend to higher rates of infection with parainfluenza 3 [19 (20%) patients in group B vs3 (7.5%) patients in group A, p=0.04] was observed in older patients.

Conclusion :

No differences on the rate and type of viral infections were noted for elderly vs non elderly patients. However, they tended to have more bacterial co-infections that led to AECOPD and longer hospitalization stays compared to non-elderly patients.