Accelerated extracellular matrix turnover during exacerbations of COPD

Background

Exacerbations of chronic obstructive pulmonary disease (COPD) contribute significantly to disease progression. However, the effect on tissue structure and turnover is not well described. There is an urgent clinical need for biomarkers of disease activity associated with disease progression. Extracellular matrix (ECM) turnover reflects activity in tissues and consequently assessment of ECM turnover may serve as biomarkers of disease activity. We hypothesized that the turnover of lung ECM proteins were altered during exacerbations of COPD.

Methods

69 patients with COPD hospitalised for an exacerbation were recruited at admission and returned for a 4 weeks follow-up. Competitive ELISAs measuring circulating protein fragments in serum or plasma assessed the formation and degradation of collagen types III (Pro-C3 and C3M, respectively), IV (P4NP 7S and C4M, respectively), and VI (Pro-C6 and C6M, respectively), and degradation of elastin (ELM7 and EL-NE) and versican (VCANM).

Results

Circulating levels of C3M, C4M, C6M, ELM7, and EL-NE were elevated during an exacerbation of COPD as compared to follow-up (all P <0.0001), while VCANM levels were decreased (P <0.0001). Pro-C6 levels were decreased and P4NP 7S levels were elevated during exacerbation (P <0.0001). Pro-C3 levels were unchanged. At time of exacerbation, degradation/formation ratios were increased for collagen types III and VI and decreased for collagen type IV.

Conclusions

Exacerbations of COPD resulted in elevated levels of circulating fragments of structural proteins, which may serve as markers of disease activity. This suggests that patients with COPD have accelerated ECM turnover during exacerbations which may be related to disease progression.     

Pulmonary biomarkers in COPD exacerbations: a systematic review

Exacerbations of COPD (ECOPD) represent a major burden for patients and health care systems. Innovative sampling techniques have led to the identification of several pulmonary biomarkers. Although some molecules are promising, their usefulness in clinical practice is not yet established. Medline and Highwire databases were used to identify studies evaluating pulmonary sampled biomarkers in ECOPD. We combined 3 terms for ECOPD, 3 for biomarkers and 6 for the sampling method. Seventy-nine studies were considered eligible for inclusion in the review and were analyzed further. Pulmonary biomarkers sampled with non-invasive, semi-invasive and invasive methods were evaluated for their potential to illustrate the disease’s clinical course, to correlate to clinical variables and to predict clinical outcomes, ECOPD etiology and response to treatment. According to published data several pulmonary biomarkers assessed in ECOPD have the potential to illustrate the natural history of disease through the modification of their levels. Among the clinically relevant molecules, those that have been studied the most and appear to be promising are spontaneous and induced sputum biomarkers for reflecting clinical severity and symptomatic recovery, as well as for directing towards an etiological diagnosis. Current evidence on the clinical usefulness of exhaled breath condensate and bronchoalveolar lavage biomarkers in ECOPD is limited. In conclusion, pulmonary biomarkers have the potential to provide information on the mechanisms underlying ECOPD, and several correlate with clinical variables and outcomes. However, on the basis of published evidence, no single molecule is adequately validated for wide clinical use. Clinical trials that incorporate biomarkers in decisional algorithms are required.     

A clinical in-hospital prognostic score for acute exacerbations of COPD

Background

The use of a severity score to help orientation decisions could improve the efficiency of care for acute exacerbations of COPD (AECOPD). We previously developed a score (‘2008 score’, based on age, dyspnea grade at steady state and number of clinical signs of severity) predicting in-hospital mortality in patients with AECOPD visiting emergency departments (EDs). External validity of this score remained to be assessed.

Objectives

To test the predictive properties of the ‘2008 score’ in a population of patients hospitalized in medical respiratory wards for AECOPD, and determine whether a new score specifically derived from this population would differ from the previous score in terms of components or predictive performance.

Methods

Data from a cohort study in 1824 patients hospitalized in a medical ward for an AECOPD were analyzed. Patients were categorized using the 2008 score and its predictive characteristics for in-hospital mortality rates were assessed. A new score was developed using multivariate logistic regression modeling in a randomly selected derivation population sample followed by testing in the remaining population (validation sample). Robustness of results was assessed by case-by-case validation.

Results

The 2008 score was characterized by a c-statistic at 0.77, a sensitivity of 69% and a specificity of 76% for prediction of in-hospital mortality. The new score comprised the same variables plus major cardiac comorbidities and was characterized by a c-statistic of 0.78, a sensitivity of 77% and specificity of 66%.

Conclusions

A score using simple clinical variables has robust properties for predicting the risk of in-hospital death in patients hospitalized for AECOPD. Adding cardiac comorbidities to the original score increased its sensitivity while decreasing its specificity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0099-9) contains supplementary material, which is available to authorized users.     

Serologic evidence of human metapneumovirus circulation in Uruguay

First identified in 2001, the human metapneumovirus (hMPV), is a respiratory tract pathogen that affects young children, elderly, and immunocompromised patients. The present work represents the first serologic study carried out in Uruguay. It was performed with the purpose of obtaining serological evidence of hMPV circulation in Uruguay and to contribute to the few serologic reports described until now. Sixty nine serum samples collected between 1998 and 2001 by vein puncture from patients without respiratory symptoms or underlying pathology aged 6 days to 60 years were examined using an indirect immunofluorescence assay (IFA). The global seropositivity rate of the samples was 80% (55/69). Rates of 60% (15/25) and 91% (40/44) were observed for the pediatric and adult cohorts, respectively. Results obtained from a longitudinal analysis of 6 children aged 6 days to 18 months are discussed. These results are a clear evidence of hMPV circulation in Uruguay, at least since 1998, and reinforce the previous data on worldwide circulation of this virus.     

Impact of statins and ACE inhibitors on mortality after COPD exacerbations

Background

The purpose of our study was to examine the association of prior outpatient use of statins and angiotensin converting enzyme (ACE) inhibitors on mortality for subjects ≥ 65 years of age hospitalized with acute COPD exacerbations.

Methods

We conducted a retrospective national cohort study using Veterans Affairs administrative data including subjects ≥65 years of age hospitalized with a COPD exacerbation. Our primary analysis was a multilevel model with the dependent variable of 90-day mortality and hospital as a random effect, controlling for preexisting comorbid conditions, demographics, and other medications prescribed.

Results

We identified 11,212 subjects with a mean age of 74.0 years, 98% were male, and 12.4% of subjects died within 90-days of hospital presentation. In this cohort, 20.3% of subjects were using statins, 32.0% were using ACE inhibitors or angiotensin II receptor blockers (ARB). After adjusting for potential confounders, current statin use (odds ratio 0.51, 95% confidence interval 0.40–0.64) and ACE inhibitor/ARB use (0.55, 0.46–0.66) were significantly associated with decreased 90-day mortality.

Conclusion

Use of statins and ACE inhibitors prior to admission is associated with decreased mortality in subjects hospitalized with a COPD exacerbation. Randomized controlled trials are needed to examine whether the use of these medications are protective for those patients with COPD exacerbations.     

Severe vitamin D deficiency is associated with frequent exacerbations and hospitalization in COPD patients

Background

Acute exacerbations of COPD (AECOPD) are common and strongly influence disease severity and relative healthcare costs. Vitamin D deficiency is frequent among COPD patients and its contributory role in disease exacerbations is widely debated. Our aim was to assess the relationship of serum vitamin D levels with COPD severity and AECOPD.

Methods

Serum vitamin D (25-hydroxyvitamin D) levels were measured in 97 COPD patients and related to lung function, comorbidities, FEV1 decline, AECOPD and hospital admission during the previous year.

Results

Most patients (96%) had vitamin D deficiency, which was severe in 35 (36%). No significant relationship was found between vitamin D and FEV1 or annual FEV1 decline. No difference between patients with and without severe vitamin D deficiency was found in age, gender, BMI, smoking history, lung function, and comorbidities, apart from osteoporosis (60.9% in severe deficiency vs 22.7%, p = 0.001). In multiple logistic regression models, severe deficiency was independently associated with AECOPD [adjusted odds ratios (aOR) of 30.5 (95% CI 5.55, 168), p < 0.001] and hospitalization [aOR 3.83 (95% CI 1.29, 11.4), p = 0.02]. The odds ratio of being a frequent exacerbator if having severe vitamin D deficiency was 18.1 (95% CI 4.98, 65.8) (p < 0.001), while that of hospitalization was 4.57 (95% CI 1.83, 11.4) (p = 0.001).

Conclusions

In COPD patients severe vitamin D deficiency was related to more frequent disease exacerbations and hospitalization during the year previous to the measurement of vitamin D. This association was independent of patients’ characteristics and comorbidities.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0131-0) contains supplementary material, which is available to authorized users.     

Molecular epidemiology and evolution of human respiratory syncytial virus and human metapneumovirus

Human respiratory syncytial virus (HRSV) and human metapneumovirus (HMPV) are ubiquitous respiratory pathogens of the Pneumovirinae subfamily of the Paramyxoviridae. Two major surface antigens are expressed by both viruses; the highly conserved fusion (F) protein, and the extremely diverse attachment (G) glycoprotein. Both viruses comprise two genetic groups, A and B. Circulation frequencies of the two genetic groups fluctuate for both viruses, giving rise to frequently observed switching of the predominantly circulating group. Nucleotide sequence data for the F and G gene regions of HRSV and HMPV variants from the UK, The Netherlands, Bangkok and data available from Genbank were used to identify clades of both viruses. Several contemporary circulating clades of HRSV and HMPV were identified by phylogenetic reconstructions. The molecular epidemiology and evolutionary dynamics of clades were modelled in parallel. Times of origin were determined and positively selected sites were identified. Sustained circulation of contemporary clades of both viruses for decades and their global dissemination demonstrated that switching of the predominant genetic group did not arise through the emergence of novel lineages each respiratory season, but through the fluctuating circulation frequencies of pre-existing lineages which undergo proliferative and eclipse phases. An abundance of sites were identified as positively selected within the G protein but not the F protein of both viruses. For HRSV, these were discordant with previously identified residues under selection, suggesting the virus can evade immune responses by generating diversity at multiple sites within linear epitopes. For both viruses, different sites were identified as positively selected between genetic groups.     

First detection of human metapneumovirus in children with respiratory infections in Romania

The human metapneumovirus (hMPV) was first isolated in 2001 in the Netherlands (Van der Hoogen and collaborators) from a nasopharyngeal aspirate sampled from an infant. Based on the morphological, biochemical and genetic characteristics, the hMPV was initially classified in the genus Metapneumovirus with the avian metapneumovirus (APV), the agent causing the respiratory infections of the upper tract in turkeys and other birds. Subsequently, together with the respiratory syncytial virus (RSV), it was classified in the Pneumovirus genus which is a part of the Pneumovirinae subfamily, the Paramyxoviridae family. The aim of the present study was to optimize hMPV molecular detection and to detect the virus in samples form children with respiratory infections in Romania. Two types of RTPCR commercial kits were evaluated for the detection of hMPV. Tests were performed on 28 pharyngeal exudates from children aged from 9 months to 6 years, which were negative for influenza viruses and for Respiratory Syncytial Virus (RSV). Among the tested samples 7 (25%) have been positive for hMPV by RT-PCR. These results document for the first time that hMPV is circulating in Romania and causes respiratory infections, especially in newborns and children under 6 years old.     

Increase human metapneumovirus mediated morbidity following pandemic influenza infection

Human metapneumovirus (hMPV) is a recently discovered respiratory pathogen, infecting mainly young children. The infected patients suffer from influenza like symptoms (ILS). In Israel the virus is mainly circulating in February to March. Here we report on an increased rate of hMPV infection in the winter season of 2009-10. The 2009-10 infection had several unique characteristics when compared to previous seasons; it started around January and a large number of infants were infected by the virus. Genetic analysis based on the viral L and F genes of hMPV showed that only subtypes A2 and B2 circulated in Israel. Additionally, we have identified a novel variant of hMPV within subgroup A2b, which subdivide it into A2b1 and A2b2. Finally, we showed that the hMPV infection was detected in the country soon after the infection with the pandemic influenza virus had declined, that infection with the pandemic influenza virus was dominant and that it interfered with the infection of other respiratory viruses. Thus, we suggest that the unusual increase in hMPV infection observed in 2009-10 was due to the appearance of the pandemic influenza virus in the winter season prior to 2009-10.     

Spirometric changes during exacerbations of COPD: a post hoc analysis of the WISDOM trial

Background

Exacerbations of chronic obstructive pulmonary disease (COPD) are associated with loss of lung function and poor outcomes for patients. However, there are limited data on the time course of changes in forced expiratory volume in 1?s (FEV₁) preceding the first reported symptom and after the start of an exacerbation.

Methods

WISDOM was a multinational, randomized, double-blind, active-controlled, 52-week study in patients with severe-to-very severe COPD. Patients received triple therapy (long-acting muscarinic antagonist and long-acting β₂-agonist/inhaled corticosteroid [ICS]) for 6?weeks, and were randomized to continue triple therapy or stepwise withdrawal of the ICS (dual bronchodilator group). After suitable training, patients performed daily spirometry at home using a portable, battery-operated spirometer. In the present post hoc analysis, patients who continued to perform daily home spirometry and completed at least one measurement per week for a 56-day period before and after the start of a moderate or severe exacerbation were included. Missing values were imputed by linear interpolation (intermittent), backfilling (beginning) or carry forward (end). Exacerbation onset was the first day of a reported symptom of exacerbation.

Results

Eight hundred and eighty-eight patients in the WISDOM study had a moderate/severe exacerbation after the complete ICS withdrawal visit; 360 of them contributed at least one FEV₁ measure per week for the 8?weeks before and after the event and are included in this analysis.Mean daily FEV₁ began to decline from approximately 2?weeks before the onset of symptoms of an exacerbation, dropping from 0.907?L (mean Days ??56 to ??36 before the exacerbation) to 0.860?L on the first day of the exacerbation. After the exacerbation, mean FEV₁ improved but did not return to pre-exacerbation levels (mean Days 36–56 after the exacerbation, 0.875?L).The pattern of FEV₁ changes around exacerbations was similar in the triple therapy and dual bronchodilator groups, and a similar pattern was seen in moderate and severe exacerbations when analysed separately.

Conclusions

Mean lung function starts to decline prior to the first reported symptoms of an exacerbation, and does not recover to pre-exacerbation levels 8?weeks after the event.

Trial registration

WISDOM (ClinicalTrials.gov number, NCT00975195).

     

Concomitant therapy with Cineole (Eucalyptole) reduces exacerbations in COPD: A placebo-controlled double-blind trial

Background

The clinical effects of mucolytics in patients with chronic obstructive pulmonary disease (COPD) are discussed controversially. Cineole is the main constituent of eucalyptus oil and mainly used in inflammatory airway diseases as a mucolytic agent. We hypothesised that its known mucolytic, bronchodilating and anti-inflammatory effects as concomitant therapy would reduce the exacerbation rate and show benefits on pulmonary function tests as well as quality of life in patients with COPD.

Methods

In this double-blind, placebo-controlled multi-center-study we randomly assigned 242 patients with stable COPD to receive 200 mg of cineole or placebo 3 times daily as concomitant therapy for 6 months during winter-time. The frequency, duration and severity of exacerbations were combined as primary outcome measures for testing as multiple criteria. Secondary outcome measures included changes of lung function, respiratory symptoms and quality of life as well as the single parameters of the exacerbations.

Results

Baseline demographics, lung function and standard medication of both groups were comparable. During the treatment period of 6 months the multiple criteria frequency, severity and duration of exacerbations were significantly lower in the group treated with cineole in comparison to placebo. Secondary outcome measures validated these findings. Improvement of lung function, dyspnea and quality of life as multiple criteria were statistically significant relative to placebo. Adverse events were comparable in both groups.

Conclusion

Concomitant therapy with cineole reduces exacerbations as well as dyspnea and improves lung function and health status. This study further suggests cineole as an active controller of airway inflammation in COPD by intervening in the pathophysiology of airway inflammation of the mucus membrane.

Trial registration

ISRCTN07600011     

The human metapneumovirus matrix protein stimulates the inflammatory immune response in vitro

Each year, during winter months, human Metapneumovirus (hMPV) is associated with epidemics of bronchiolitis resulting in the hospitalization of many infants. Bronchiolitis is an acute illness of the lower respiratory tract with a consequent inflammation of the bronchioles. The rapid onset of inflammation suggests the innate immune response may have a role to play in the pathogenesis of this hMPV infection. Since, the matrix protein is one of the most abundant proteins in the Paramyxoviridae family virion, we hypothesized that the inflammatory modulation observed in hMPV infected patients may be partly associated with the matrix protein (M-hMPV) response. By western blot analysis, we detected a soluble form of M-hMPV released from hMPV infected cell as well as from M-hMPV transfected HEK 293T cells suggesting that M-hMPV may be directly in contact with antigen presenting cells (APCs) during the course of infection. Moreover, flow cytometry and confocal microscopy allowed determining that M-hMPV was taken up by dendritic cells (moDCs) and macrophages inducing their activation. Furthermore, these moDCs enter into a maturation process inducing the secretion of a broad range of inflammatory cytokines when exposed to M-hMPV. Additionally, M-hMPV activated DCs were shown to stimulate IL-2 and IFN-γ production by allogeneic T lymphocytes. This M-hMPV-mediated activation and antigen presentation of APCs may in part explain the marked inflammatory immune response observed in pathology induced by hMPV in patients.     

Potential electrostatic interactions in multiple regions affect human metapneumovirus f-mediated membrane fusion

The recently identified human metapneumovirus (HMPV) is a worldwide respiratory virus affecting all age groups and causing pneumonia and bronchiolitis in severe cases. Despite its clinical significance, no specific antiviral agents have been approved for treatment of HMPV infection. Unlike the case for most paramyxoviruses, the fusion proteins (F) of a number of strains, including the clinical isolate CAN97-83, can be triggered by low pH. We recently reported that residue H435 in the HRB linker domain acts as a pH sensor for HMPV CAN97-83 F, likely through electrostatic repulsion forces between a protonated H435 and its surrounding basic residues, K295, R396, and K438, at low pH. Through site-directed mutagenesis, we demonstrated that a positive charge at position 435 is required but not sufficient for F-mediated membrane fusion. Arginine or lysine substitution at position 435 resulted in a hyperfusogenic F protein, while replacement with aspartate or glutamate abolished fusion activity. Studies with recombinant viruses carrying mutations in this region confirmed its importance. Furthermore, a second region within the F(2) domain identified as being rich in charged residues was found to modulate fusion activity of HMPV F. Loss of charge at residues E51, D54, and E56 altered local folding and overall stability of the F protein, with dramatic consequences for fusion activity. As a whole, these studies implicate charged residues and potential electrostatic interactions in function, pH sensing, and overall stability of HMPV F.     

Cytotoxic T-lymphocyte epitope vaccination protects against human metapneumovirus infection and disease in mice

Human metapneumovirus (hMPV) has emerged as an important human respiratory pathogen causing upper and lower respiratory tract infections in young children and older adults. In addition, hMPV infection is associated with asthma exacerbation in young children. Recent epidemiological evidence indicates that hMPV may cocirculate with human respiratory syncytial virus (hRSV) and mediate clinical disease similar to that seen with hRSV. Therefore, a vaccine for hMPV is highly desirable. In the present study, we used predictive bioinformatics, peptide immunization, and functional T-cell assays to define hMPV cytotoxic T-lymphocyte (CTL) epitopes recognized by mouse T cells restricted through several major histocompatibility complex class I alleles, including HLA-A*0201. We demonstrate that peptide immunization with hMPV CTL epitopes reduces viral load and immunopathology in the lungs of hMPV-challenged mice and enhances the expression of Th1-type cytokines (gamma interferon and interleukin-12 [IL-12]) in lungs and regional lymph nodes. In addition, we show that levels of Th2-type cytokines (IL-10 and IL-4) are significantly lower in hMPV CTL epitope-vaccinated mice challenged with hMPV. These results demonstrate for the first time the efficacy of an hMPV CTL epitope vaccine in the control of hMPV infection in a murine model.     

T lymphocytes contribute to antiviral immunity and pathogenesis in experimental human metapneumovirus infection

Human metapneumovirus (hMPV), a member of the family Paramyxoviridae, is a leading cause of lower respiratory tract infections in children, the elderly, and immunocompromised patients. Virus- and host-specific mechanisms of pathogenesis and immune protection are not fully understood. By an intranasal inoculation model, we show that hMPV-infected BALB/c mice developed clinical disease, including airway obstruction and hyperresponsiveness (AHR), along with histopathologic evidence of lung inflammation and viral replication. hMPV infection protected mice against subsequent viral challenge, as demonstrated by undetectable viral titers, lack of body weight loss, and a significant reduction in the level of lung inflammation. No cross-protection with other paramyxoviruses, such as respiratory syncytial virus, was observed. T-lymphocyte depletion studies showed that CD4⁺ and CD8⁺ T cells cooperate synergistically in hMPV eradication during primary infection, but CD4⁺ more than CD8⁺ T cells also enhanced clinical disease and lung pathology. Concurrent depletion of CD4⁺ and CD8⁺ T cells completely blocked airway obstruction as well as AHR. Despite impaired generation of neutralizing anti-hMPV antibodies in the absence of CD4⁺ T cells, mice had undetectable viral replication after hMPV challenge and were protected from clinical disease, suggesting that protection can be provided by an intact CD8⁺ T-cell compartment. Whether these findings have implications for naturally acquired human infections remains to be determined.     

Recovery of human metapneumovirus genetic lineages a and B from cloned cDNA

Human metapneumovirus (hMPV) is a newly discovered pathogen associated with respiratory tract illness, primarily in young children, immunocompromised individuals, and the elderly. The genomic sequence of the prototype hMPV isolate NL/1/00 without the terminal leader and trailer sequences has been reported previously. Here we describe the leader and trailer sequences of two hMPV isolates, NL/1/00 and NL/1/99, representing the two main genetic lineages of hMPV. Minigenome constructs in which the green fluorescent protein or chloramphenicol acetyltransferase genes are flanked by the viral genomic ends derived from both hMPV lineages and transcribed using a T7 RNA polymerase promoter-terminator cassette were generated. Cotransfection of minigenome constructs with plasmids expressing the polymerase complex components L, P, N, and M2.1 in 293T or baby hamster kidney cells resulted in expression of the reporter genes. When the minigenome was replaced by a sense or antisense full-length cDNA copy of the NL/1/00 or NL/1/99 viral genomes, recombinant virus was recovered from transfected cells. Viral titers up to 10(7.2) and 10(5.7) 50% tissue culture infective dose/ml were achieved with the sense and antisense plasmids, respectively. The recombinant viruses replicated with kinetics similar to those of the parental viruses in Vero cells. This reverse genetics system provides an important new tool for applied and fundamental research.     

Co-infection of human metapneumovirus with adenovirus or respiratory syncytial virus among children in Japan

Human metapneumovirus (hMPV) is one of the etiological agents of acute respiratory tract infections. From June 2005 to May 2006, we collected 185 clinical specimens from children in Osaka City, Japan, and detected 41 hMPV RNA. Of the 41 specimens, four (9.8%) also contained other viruses (3 with adenovirus [AdV] and 1 with respiratory syncytial virus [RSV]). The clinical symptoms of patients coinfected with AdV were indistinct from those of patients mono-infected with hMPV. The symptoms of the one patient co-infected with RSV were clinically severe. Further research is needed to clarify the effect of hMPV on other respiratory viruses or vice versa.