Viral infections in obstructive airway diseases

Respiratory Syncytial Virus: Infection, Detection, and New Options for Prevention and Treatment

Respiratory syncytial virus (RSV) infection is a significant cause of hospitalization of children in North America and one of the leading causes of death of infants less than 1 year of age worldwide, second only to malaria. Despite its global impact on human health, there are relatively few therapeutic options available to prevent or treat RSV infection. Paradoxically, there is a very large volume of information that is constantly being refined on RSV replication, the mechanisms of RSV-induced pathology, and community transmission. Compounding the burden of acute RSV infections is the exacerbation of preexisting chronic airway diseases and the chronic sequelae of RSV infection. A mechanistic link is even starting to emerge between asthma and those who suffer severe RSV infection early in childhood. In this article, we discuss developments in the understanding of RSV replication, pathogenesis, diagnostics, and therapeutics. We attempt to reconcile the large body of information on RSV and why after many clinical trials there is still no efficacious RSV vaccine and few therapeutics.

Productive Infection of Human Embryonic Stem Cell-Derived NKX2.1+ Respiratory Progenitors with Human Rhinovirus

Airway epithelial cells generated from pluripotent stem cells (PSCs) represent a resource for research into a variety of human respiratory conditions, including those resulting from infection with common human pathogens. Using an NKX2.1-GFP reporter human embryonic stem cell line, we developed a serum-free protocol for the generation of NKX2.1(+) endoderm that, when transplanted into immunodeficient mice, matured into respiratory cell types identified by expression of CC10, MUC5AC, and surfactant proteins. Gene profiling experiments indicated that day 10 NKX2.1(+) endoderm expressed markers indicative of early foregut but lacked genes associated with later stages of respiratory epithelial cell differentiation. Nevertheless, NKX2.1(+) endoderm supported the infection and replication of the common respiratory pathogen human rhinovirus HRV1b. Moreover, NKX2.1(+) endoderm upregulated expression of IL-6, IL-8, and IL-1B in response to infection, a characteristic of human airway epithelial cells. Our experiments provide proof of principle for the use of PSC-derived respiratory epithelial cells in the study of cell-virus interactions.

SIGNIFICANCE

This report provides proof-of-principle experiments demonstrating, for the first time, that human respiratory progenitor cells derived from stem cells in the laboratory can be productively infected with human rhinovirus, the predominant cause of the common cold.

AcuteChlamydia pneumoniaeandMycoplasma pneumoniaeInfections in Community-Acquired Pneumonia and Exacerbations of COPD or Asthma: Therapeutic Considerations

Rates of acute Chlamydia pneumoniae and Mycoplasma pneumoniae infections were determined in 115 adults hospitalized for community-acquired pneumonia (CAP), purulent exacerbations of COPD and acute exacerbations of bronchial asthma, by means of serology and molecular methods. Results were compared with those obtained in a matched control group. Common respiratory pathogens were isolated by cultures in 22.5% and 22.2% of CAP and exacerbated COPD patients, respectively. Cultures from exacerbated asthma patients were always negative. Serological and molecular evidence of current C. pneumoniae infection was obtained in 10.0%, 8.9% and 3.3% of CAP, COPD and asthma cases. The corresponding rates of acute M. pneumoniae infection were 17.5%, 6.7% and 3.3%, respectively. Finally, no difference was found between typical and atypical pathogen rates. These findings highlight the importance of taking into account C. pneumoniae and M. pneumoniae infections in guiding the choice of empirical antibacterial treatment for CAP and purulent exacerbations of COPD.

Guidelines for diagnosis and management of chronic obstructive pulmonary disease: Joint ICS/NCCP (I) recommendations

Chronic obstructive pulmonary disease (COPD) is a major public health problem in India. Although several International guidelines for diagnosis and management of COPD are available, yet there are lot of gaps in recognition and management of COPD in India due to vast differences in availability and affordability of healthcare facilities across the country. The Indian Chest Society (ICS) and the National College of Chest Physicians (NCCP) of India have joined hands to come out with these evidence-based guidelines to help the physicians at all levels of healthcare to diagnose and manage COPD in a scientific manner. Besides the International literature, the Indian studies were specifically analyzed to arrive at simple and practical recommendations. The evidence is presented under these five headings: (a) definitions, epidemiology, and disease burden; (b) disease assessment and diagnosis; (c) pharmacologic management of stable COPD; (d) management of acute exacerbations; and (e) nonpharmacologic and preventive measures. The modified grade system was used for classifying the quality of evidence as 1, 2, 3, or usual practice point (UPP). The strength of recommendation was graded as A or B depending upon the level of evidence.

Monocyte differentiation toward regulatory dendritic cells is not affected by respiratory syncytial virus-induced inflammatory mediators

Airway epithelial cells were shown to drive the differentiation of monocytes into dendritic cells (DCs) with a suppressive phenotype. In this study, we investigated the impact of virus-induced inflammatory mediator production on the development of DCs. Monocyte differentiation into functional DCs, as reflected by the expression of CD11c, CD123, BDCA-4, and DC-SIGN and the capacity to activate T cells, was similar for respiratory syncytial virus (RSV)-infected and mock-infected BEAS-2B and A549 cells. RSV-conditioned culture media resulted in a partially mature DC phenotype, but failed to up-regulate CD80, CD83, CD86, and CCR7, and failed to release proinflammatory mediators upon Toll-like receptor (TLR) triggering. Nevertheless, these DCs were able to maintain an antiviral response by the release of Type I IFN. Collectively, these data indicate that the airway epithelium maintains an important suppressive DC phenotype under the inflammatory conditions induced by infection with RSV.

Species differences in the pharmacology and toxicology of PEGylated helper-dependent adenovirus

Clinically relevant doses of helper-dependent adenoviruses (HDAds) provoke the host response against capsid proteins in primates and rodents. To determine if PEGylation truly affects this, baboons and mice were given either HDAd or PEG-HDAd expressing beta-galactosidase at 5 × 10¹¹ or 3 × 10¹² virus particles per kilogram (vp/kg) by iv infusion. Serum cytokines and blood chemistries were assessed for 96 h. PEG-HDAd reduced IL-6 6-fold in mice and 3-fold in the primate. This vector reduced IL-12 by 50% in both animal models. PEGylation reduced serum transaminases by approximately 50% at each dose in the primate and the mouse. PEGylation did not alter hepatic transduction efficiency in the mouse but did reduce transduction efficiency in the liver and the spleen of primates. Unmodified and PEGylated virus suppressed hepatic CYP3A activity in both animal models. PEGylation doubled the half-life (t(½)) of the virus in the mouse and cut plasma clearance (CL) in half without affecting the half-life in primates. These results suggest that there are notable species-specific differences in the biodistribution of and response to PEG-modified vectors which may be linked to differences in binding properties to coagulation factors, receptor density and tissue architecture in the liver.

Human rhinovirus proteinase 2A induces TH1 and TH2 immunity in patients with chronic obstructive pulmonary disease

BACKGROUND

Tobacco-related lung diseases, including chronic obstructive pulmonary disease (COPD), are major causes of lung-related disability and death worldwide. Acute exacerbation of COPD (AE-COPD) is commonly associated with upper and lower respiratory tract viral infections and can result in respiratory failure in those with advanced lung disease.

OBJECTIVE

We sought to determine the mechanism underlying COPD exacerbation and host response to pathogen-derived factors.

METHODS

Over a 24-month period, we assessed the viral causes for upper and lower respiratory tract infections in patients with COPD (n = 155) and control subjects (n = 103). We collected nasal and bronchoalveolar lavage fluid and peripheral blood under baseline and exacerbated conditions. We determined the effect of human rhinovirus (HRV) proteinases on T-cell activation in human subjects and mice.

RESULTS

HRVs are isolated from nasal and lung fluid from subjects with AE-COPD. Bronchoalveolar lavage fluid and CD4 T cells from patients with COPD exhibited a T(H)1 and T(H)2 cell cytokine phenotype during acute infection. HRV-encoded proteinase 2A activated monocyte-derived dendritic cells in vitro and induced strong T(H)1 and T(H)2 immune responses from CD4 T cells. Intranasal administration of recombinant rhinovirus proteinase 2A in mice resulted in an increase in airway hyperreactivity, lung inflammation, and IL-4 and IFN-gamma production from CD4 T cells.

CONCLUSION

Our findings suggest that patients with severe COPD show T(H)1- and T(H)2-biased responses during AE-COPD. HRV-encoded proteinase 2A, like other microbial proteinases, could provide a T(H)1- and T(H)2-biasing adjuvant factor during upper and lower respiratory tract infection in patients with severe COPD. Alteration of the immune response to secreted viral proteinases might contribute to worsening of dyspnea and respiratory failure in patients with COPD.

Chronic obstructive pulmonary disease: role of bacteria and updated guide to antibacterial selection in the older patient

Chronic obstructive pulmonary disease (COPD) remains a major cause of morbidity and mortality worldwide. COPD is especially prevalent in the elderly, affecting 25% of those aged>or=75 years. The course of the disease in the elderly is often complicated by co-morbid conditions, and its management is complicated by drug-drug interactions. Exacerbations of COPD increase rates of hospitalization and mortality and decrease quality of life. Exacerbations are marked by an increase from baseline in dyspnoea, sputum volume and sputum purulence. Approximately 50% of acute exacerbations of symptoms in COPD are caused by non-typeable Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae and Pseudomonas aeruginosa. Stratification of exacerbations based on severity of symptoms and signs, and severity of underlying COPD, is useful in selecting patients likely to benefit from antibacterial therapy. Patients who are hospitalized with exacerbations, those who have all three symptoms (increased dyspnoea, sputum volume and sputum purulence), and those with severe underlying COPD and exacerbations benefit most from antibacterials. Antibacterial susceptibility patterns among the bacterial pathogens are evolving, and knowledge of local susceptibility patterns is useful in antibacterial selection. Penicillin, amoxicillin, cotrimoxazole (trimethoprim/sulfamethoxazole) and doxycycline should not be used as an initial antibacterial because of resistance patterns. We recommend second-/third-generation cephalosporins, amoxicillin/clavulanic acid, azithromycin and respiratory fluoroquinolones as initial choices. In patients at risk of colonization by, and infection as a result of, P. aeruginosa, ciprofloxacin, levofloxacin or an advanced penicillin/penicillinase combination effective against this species should be used. Drug-drug interactions should be considered in antibacterial choice. The goals of antibacterial therapy for exacerbations of COPD are the prevention of complications such as respiratory failure and death, and the reduction of treatment failures. The role of pathogenic bacteria in progression of stable COPD and the use of prophylactic antibacterials in stable COPD are under investigation. Currently available evidence does not support routine clinical use of prophylactic antibacterials in stable COPD. In conclusion, pathogenic bacteria cause a significant proportion of acute exacerbations of COPD. Use of antibacterials, based on current susceptibility patterns, is beneficial in patients with severe COPD experiencing exacerbations and in patients with severe exacerbations.

Resolution of cell-mediated airways diseases

"Inflammation resolution" has of late become a topical research area. Activation of resolution phase mechanisms, involving select post-transcriptional regulons, transcription factors, 'autacoids', and cell phenotypes, is now considered to resolve inflammatory diseases. Critical to this discourse on resolution is the elimination of inflammatory cells through apoptosis and phagocytosis. For major inflammatory diseases such as asthma and COPD we propose an alternative path to apoptosis for cell elimination. We argue that transepithelial migration of airway wall leukocytes, followed by mucociliary clearance, efficiently and non-injuriously eliminates pro-inflammatory cells from diseased airway tissues. First, it seems clear that numerous infiltrated granulocytes and lymphocytes can be speedily transmitted into the airway lumen without harming the epithelial barrier. Then there are a wide range of 'unexpected' findings demonstrating that clinical improvement of asthma and COPD is not only associated with decreasing numbers of airway wall inflammatory cells but also with increasing numbers of these cells in the airway lumen. Finally, effects of inhibition of transepithelial migration support the present hypothesis. Airway inflammatory processes have thus been much aggravated when transepithelial exit of leukocytes has been inhibited. In conclusion, the present hypothesis highlights risks involved in drug-induced inhibition of transepithelial migration of airway wall leukocytes. It helps interpretation of common airway lumen data, and suggests approaches to treat cell-mediated airway inflammation.

Identifying viral infections in vaccinated Chronic Obstructive Pulmonary Disease (COPD) patients using clinical features and inflammatory markers

Background  Known inflammatory markers have limited sensitivity and specificity to differentiate viral respiratory tract infections from other causes of acute exacerbation of COPD (AECOPD). To overcome this, we developed a multi‐factorial prediction model combining viral symptoms with inflammatory markers.

Methods  Interleukin‐6 (IL‐6), serum amyloid A (SAA) and viral symptoms were measured in stable COPD and at AECOPD onset and compared with the viral detection rates on multiplex PCR. The predictive accuracy of each measure was assessed using logistic regression and receiver operating characteristics curve (ROC) analysis.

Results  There was a total of 33 viruses detected at the onset of 148 AECOPD, the majority 26 (79%) were picornavirus. Viral symptoms with the highest predictive values were rhinorrhoea [Odds ratio (OR) 4·52; 95% CI 1·99–10·29; P < 0·001] and sore throat (OR 2·64; 95% CI 1·14–6·08; P = 0·022), combined the AUC ROC curve was 0·67. At AECOPD onset patients experienced a 1·6‐fold increase in IL‐6 (P = 0·008) and 4·5‐fold increase in SAA (P < 0·001). The addition of IL‐6 to the above model significantly improved diagnostic accuracy compared with symptoms alone (AUC ROC 0·80 (P = 0·012).

Conclusion  The addition of inflammatory markers increases the specificity of a clinical case definition for viral infection, particularly picornavirus infection.

Long-term virus-induced alterations of CYP3A-mediated drug metabolism: a look at the virology, immunology and molecular biology of a multi-faceted problem

Virus infections are on the rise. Although the first description of CYP expression during virus infection was recorded 50 years ago, mechanistic studies of this phenomenon only began to appear in the last decade due to breakthroughs in molecular biology, genomic and transgenic technology. This review describes the relationship(s) among CYP-mediated drug metabolism, virus infection and the immune response and evaluates in vitro and in vivo models for mechanistic studies. The first studies that assessed CYP expression during infection focused on inflammatory mediators and the innate immune response at early time points. Recent studies assessing virus infection and its effect on hepatic CYP expression noted more long-term effects. An obvious approach toward understanding how viruses affect hepatic CYP3A expression and function would be to assess key regulators of CYP during infection. Improvements in techniques to identify post-translational modifications of CYP and systems that focus on virus-receptor interactions which allow subtraction and addition of immunological and regulatory elements that drive CYP will demonstrate that long-term changes in drug metabolism start from the time the virus enters the circulation, are reinforced by virus binding to cellular targets and further solidified by changes in cellular processes long after the virus is cleared.

Importance of viral and bacterial infections in chronic obstructive pulmonary disease exacerbations

Background

Few studies have evaluated the contribution of both viruses and bacteria in acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Objectives

This study estimated the burden of both types of pathogens among adults seeking care for an AECOPD during two consecutive winter seasons.

Study design

Patients 50 years or older who consulted within 10 days of AECOPD onset were eligible. Clinical data were collected on a standardized questionnaire, and nasopharyngeal aspirates (NPA), paired sera, and non-induced sputum were collected. Polymerase chain reaction (PRC) assays were used to identify viral, atypical and bacterial pathogens in NPA specimen.

Results

Overall, 108 patients with AECOPD were included, 88% of patients were admitted and 2 patients (2%) received intensive care. A third of patients (31%) had evidence of a viral infection, 9% with influenza A, 7% RSV and 7% with PIV-3. One patient was positive for Mycoplasma pneumoniae. Bacterial pathogens were identified in 49% of patients with available sputum, most frequently Staphylococcus aureus, Pseudomonas aeruginosa, and Haemophilus influenzae. Among virus-infected patients, 14 (58%) also had bacteria in their sputum, but co-infected patients did not present with different symptoms than patients with single infections.

Conclusions

These results suggest that influenza and RSV are frequent contributors of AECOPD, and that coinfection with bacteria does not appear to be more severe among virus-infected patients. Clinicians should be aware that AECOPD may be frequently triggered by viruses, and may consider antivirals and proper infection control measures in appropriate epidemiological setting.

Drug-virus interaction: effect of administration of recombinant adenoviruses on the pharmacokinetics of docetaxel in a rat model

Modern cancer therapy combines recombinant viruses with traditional chemotherapeutic agents that are metabolized by hepatic cytochrome P450 3A4 (CYP3A4). A single dose of recombinant adenovirus (Ad) expressing beta-galactosidase (AdlacZ) significantly alters CYP3A2, the correlate of CYP3A4, in rats for 14 days. Recombinant adenovirus expressing human p53 (Adp53) also suppresses CYP3A2. Plasma clearance of docetaxel (DTX) in animals given AdlacZ (3.38 ± 0.22 L/h/kg) was significantly lower than that of those given DTX alone (6.41 ± 1.10 L/h/kg, p≤0.05). Area under the plasma concentration-time curve of DTX in rats given AdlacZ (2,987.37 ± 197.97 ng/ml/h) was significantly greater than those given drug alone (1,666.59 ± 317.04 ng/ml/h, p≤0.05). Both viruses prolonged DTX half-life (t_1/2). Ad infection may cause significant variability in the pharmacokinetics and pharmacodynamics of anti-cancer agents and should be considered when designing therapeutic regimens for patients with viral infection and those enrolled in clinical trials employing recombinant viruses.

Human metapneumovirus infection in adults

Human metapneumovirus (hMPV) was first identified in 2001 in Dutch children with bronchiolitis. The virus is an RNA virus in the Pneumovirinae subfamily and is most closely related to respiratory syncytial virus. hMPV has been shown to have worldwide circulation with nearly universal infection by age 5. Similar to influenza and respiratory syncytial virus, activity is greatest during the winter in temperate climates. Most of the available data on the clinical manifestations of hMPV infection are from studies of children where the virus causes upper respiratory tract infections, bronchiolitis, and pneumonia. Reinfections with hMPV occur throughout adult life and hMPV infection has been documented in 1-9% of adults each year using RT-PCR and serology for diagnosis. Illness is generally mild in young adults with serologic evidence of asymptomatic infection in many cases. Adults at highest risk of serious sequelae as a result of hMPV include the elderly, adults with underlying pulmonary disease, and those who are immunocompromised. Outbreaks of hMPV have been documented in long term care facilities with mortality of up to 50% in frail elderly residents. In addition, 6-12% of exacerbations of chronic obstructive pulmonary disease have been associated with hMPV and underlying lung disease is common in patients hospitalized with hMPV. Lastly, hMPV has been linked with severe idiopathic pneumonia in recipients of hematopoietic stem cell transplants. Although the true spectrum of adult hMPV remains to be defined, it is clear that hMPV can result in severe illness the frail elderly and adults with underlying diseases.

Molecular and macromolecular alterations of recombinant adenoviral vectors do not resolve changes in hepatic drug metabolism during infection

In this report we test the hypothesis that long-term virus-induced alterations in CYP occur from changes initiated by the virus that may not be related to the immune response. Enzyme activity, protein expression and mRNA of CYP3A2, a correlate of human CYP3A4, and CYP2C11, responsive to inflammatory mediators, were assessed 0.25, 1, 4, and 14 days after administration of several different recombinant adenoviruses at a dose of 5.7 × 10¹² virus particles (vp)/kg to male Sprague Dawley rats. Wild type adenovirus, containing all viral genes, suppressed CYP3A2 and 2C11 activity by 37% and 39%, respectively within six hours. Levels fell to 67% (CYP3A2) and 79% (CYP2C11) of control by 14 days (p ≤ 0.01). Helper-dependent adenovirus, with all viral genes removed, suppressed CYP3A2 (43%) and CYP2C11 (55%) within six hours. CYP3A2 remained significantly suppressed (47%, 14 days, p ≤ 0.01) while CYP2C11 returned to baseline at this time. CYP3A2 and 2C11 were reduced by 45 and 42% respectively 6 hours after treatment with PEGylated adenovirus, which has a low immunological profile (p ≤ 0.05). CYP3A2 remained suppressed (34%, p ≤ 0.05) for 14 days while CYP2C11 recovered. Inactivated virus suppressed CYP3A2 activity by 25–50% for 14 days (p ≤ 0.05). CYP2C11 was affected similar manner but recovered by day 14. Microarray and in vitro studies suggest that changes in cellular signaling pathways initiated early in virus infection contribute to changes in CYP.

Molecular mechanisms in chronic obstructive pulmonary disease: potential targets for therapy

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease associated with progressive airflow obstruction. Tobacco smoking is the main risk factor worldwide. In contrast to asthma, antiinflammatory therapies are rather ineffective in improving chronic symptoms and reducing inflammation, lung function decline, and airway remodeling. Specific drugs that are directed against the remodeling and chronic inflammation, thereby preventing lung tissue damage and progressive lung function decline, must be developed. Experimental models and expression studies suggest that anti-vascular endothelial growth factor (VEGF) receptor strategies may be of use in patients with emphysema, whereas anti-HER1-directed strategies may be more useful in patients with pulmonary mucus hypersecretion, as seen in chronic bronchitis and asthma. Growth factors and cytokines including VEGF, fibroblast growth factors, transforming growth factor-beta, tumor necrosis factor-alpha, CXCL1, CXCL8, and CCL2, and signal transduction proteins such as mitogen-activated protein kinase p38 and nuclear factor-kappaB, seem to be important pathogenetic molecules in COPD. Specific antagonists for these proteins may be effective for different inflammatory diseases. However, their efficacy for COPD therapy has not yet been demonstrated. Finally, other drugs such as retinoic acids may provide restoration of lung tissue structure. Such approaches, however, must await the first results of growth factor or cytokine antagonist therapy in chronic lung diseases.

Antibiotikatherapie bei Exazerbation

Bacterial infections are involved in approximately 50% of acute exacerbations of chronic bronchitis (AECB). Pneumococci, Haemophilus influenzae and Moraxella catarrhalis are the main pathogens. Studies using quantitative cultures and molecular typing suggest a causal relationship between bacterial infection and exacerbation. Furthermore, an association between infection and bronchial inflammation has been demonstrated. In contrast to steroid therapy and non-invasive ventilation, the benefits of antibiotic treatment are not well established. Current guidelines recommend antimicrobial therapy for AECB in type I exacerbations, for patients needing ventilatory support and for patients with cardiac comorbidity. Bacterial eradication is able to prolong the infection free interval.

Infections and Airway Inflammation in Chronic Obstructive Pulmonary Disease Severe Exacerbations

RATIONALE

Severe exacerbations of chronic obstructive pulmonary disease (COPD) are major causes of health care costs mostly related to hospitalization. The role of infections in COPD exacerbations is controversial.

OBJECTIVES

We investigated whether COPD exacerbations requiring hospitalization are associated with viral and/or bacterial infection and evaluated relationships among infection, exacerbation severity, assessed by reduction of FEV1, and specific patterns of airway inflammation.

METHODS

We examined 64 patients with COPD when hospitalized for exacerbations, and when in stable convalescence. We measured lung function, blood gases, and exhaled nitric oxide, and examined sputum for inflammation and for viral and bacterial infection.

RESULTS

Exacerbations were associated with impaired lung function (p < 0.01) and increased sputum neutrophilia (p < 0.001). Viral and/or bacterial infection was detected in 78% of exacerbations: viruses in 48.4% (6.2% when stable, p < 0.001) and bacteria in 54.7% (37.5% when stable, p = 0.08). Patients with infectious exacerbations (29.7% bacterial, 23.4% viral, 25% viral/bacterial coinfection) had longer hospitalizations (p < 0.02) and greater impairment of several measures of lung function (all p < 0.05) than those with noninfectious exacerbations. Patients with exacerbations with coinfection had more marked lung function impairment (p < 0.02) and longer hospitalizations (p = 0.001). Sputum neutrophils were increased in all exacerbations (p < 0.001) and were related to their severity (p < 0.001), independently of the association with viral or bacterial infections; sputum eosinophils were increased during (p < 0.001) virus-associated exacerbations.

CONCLUSIONS

Respiratory infections are associated with the majority of COPD exacerbations and their severity, especially those with viral/bacterial coinfection. Airway neutrophilia is related to exacerbation severity regardless of viral and/or bacterial infections. Eosinophilia is a good predictor of viral exacerbations.

Markers of exacerbation severity in chronic obstructive pulmonary disease

Background

Patients with chronic obstructive pulmonary disease (COPD) can experience 'exacerbations' of their conditions. An exacerbation is an event defined in terms of subjective descriptors or symptoms, namely dyspnoea, cough and sputum that worsen sufficiently to warrant a change in medical management. There is a need for reliable markers that reflect the pathological mechanisms that underlie exacerbation severity and that can be used as a surrogate to assess treatment effects in clinical studies. Little is known as to how existing study variables and suggested markers change in both the stable and exacerbation phases of COPD. In an attempt to find the best surrogates for exacerbations, we have reviewed the literature to identify which of these markers change in a consistent manner with the severity of the exacerbation event.

Methods

We have searched standard databases between 1966 to July 2004 using major keywords and terms. Studies that provided demographics, spirometry, potential markers, and clear eligibility criteria were included in this study. Central tendencies and dispersions for all the variables and markers reported and collected by us were first tabulated according to sample size and ATS/ERS 2004 Exacerbation Severity Levels I to III criteria. Due to the possible similarity of patients in Levels II and III, the data was also redefined into categories of exacerbations, namely out-patient (Level I) and in-patient (Levels II & III combined). For both approaches, we performed a fixed effect meta-analysis on each of the reported variables.

Results

We included a total of 268 studies reported between 1979 to July 2004. These studies investigated 142,407 patients with COPD. Arterial carbon dioxide tension and breathing rate were statistically different between all levels of exacerbation severity and between in out- and in-patient settings. Most other measures showed weak relationships with either level or setting, or they had insufficient data to permit meta-analysis.

Conclusion

Arterial carbon dioxide and breathing rate varied in a consistent manner with exacerbation severity and patient setting. Many other measures showed weak correlations that should be further explored in future longitudinal studies or assessed using suggested mathematical modelling techniques.

Respiratory viruses augment the adhesion of bacterial pathogens to respiratory epithelium in a viral species- and cell type-dependent manner

Secondary bacterial infections often complicate respiratory viral infections, but the mechanisms whereby viruses predispose to bacterial disease are not completely understood. We determined the effects of infection with respiratory syncytial virus (RSV), human parainfluenza virus 3 (HPIV-3), and influenza virus on the abilities of nontypeable Haemophilus influenzae and Streptococcus pneumoniae to adhere to respiratory epithelial cells and how these viruses alter the expression of known receptors for these bacteria. All viruses enhanced bacterial adhesion to primary and immortalized cell lines. RSV and HPIV-3 infection increased the expression of several known receptors for pathogenic bacteria by primary bronchial epithelial cells and A549 cells but not by primary small airway epithelial cells. Influenza virus infection did not alter receptor expression. Paramyxoviruses augmented bacterial adherence to primary bronchial epithelial cells and immortalized cell lines by up-regulating eukaryotic cell receptors for these pathogens, whereas this mechanism was less significant in primary small airway epithelial cells and in influenza virus infections. Respiratory viruses promote bacterial adhesion to respiratory epithelial cells, a process that may increase bacterial colonization and contribute to disease. These studies highlight the distinct responses of different cell types to viral infection and the need to consider this variation when interpreting studies of the interactions between respiratory cells and viral pathogens.

Exacerbations of chronic obstructive pulmonary disease and chronic mucus hypersecretion

Chronic obstructive pulmonary disease (COPD) exacerbations are an important cause of the considerable morbidity and mortality found in COPD. COPD exacerbations increase with increasing severity of COPD, and some patients are prone to frequent exacerbations leading to hospital admission and readmission. These frequent exacerbations may have considerable impact on quality of life and activities of daily living. Factors that increase the risk for COPD exacerbations are associated with increased airway inflammation caused by common pollutants and bacterial and/or viral infections. These inflammatory responses cause mucus hypersecretion and, thereby, airway obstruction and associated exacerbations. While chronic mucus hypersecretion is a significant risk factor for frequent and severe exacerbations, patients with chronic mucus hypersecretion have a lower rate of relapse after initial treatment for acute exacerbation. The benefit of antibiotics for treatment of COPD exacerbations is small but significant. While the mechanisms of actions are not clear, mucolytic agents reduce the number of days of disability in subjects with exacerbations. Reducing mucous cell numbers in small airways could be a useful way to reduce chronic mucus hypersecretion. Our studies suggest that programmed cell death is crucial in the resolution of metaplastic mucous cells, and understanding these mechanisms may provide novel therapies to reduce the risk of COPD exacerbations.

Detection of respiratory syncytial virus in adults with chronic obstructive pulmonary disease

RATIONALE

Recently, respiratory syncytial virus (RSV) RNA has been identified by reverse transcriptase-polymerase chain reaction (RT-PCR) from a high percentage of patients with stable chronic obstructive pulmonary disease (COPD). These data raise the possibility of persistent low-grade infection in this population, which could have implications in COPD pathogenesis.

OBJECTIVES

RSV persistence was investigated by testing respiratory secretions from subjects with COPD during illness and at regular intervals over 1 yr.

METHODS

Nasal and sputum samples from subjects with COPD were tested by one-tube nested RT-PCR for RSV every 2 mo and during respiratory illnesses for 1 yr. Subjects positive for RSV were evaluated weekly until negative in two consecutive samples. Nasal secretions and serum were tested for RSV antibody. A rise of fourfold or greater was defined as evidence of RSV infection.

RESULTS

A total of 112 patients were enrolled and the illnesses of 92 patients were evaluated. RSV was detected by RT-PCR in 6/92 (6.5%) illness nasal samples versus 0/685 routine nasal samples and in 5/69 (7.2%) illness sputum samples versus 3 /315 (0.9%) routine. Four additional RSV infections were identified by serum antibody responses. Of the RSV infections 86% were associated with serum or nasal antibody responses and 73% had symptoms of acute respiratory illness.

CONCLUSIONS

Most RSV infections in patients with COPD are associated with symptomatic respiratory illnesses and measurable immune responses. Our data do not support the concept of RSV persistence in this population.

Interleukin-8 mRNA synthesis and protein secretion are continuously up-regulated by respiratory syncytial virus persistently infected cells

The aim of this study was to investigate whether respiratory syncytial virus persistence regulates interleukin 8 (IL-8) mRNA synthesis and protein secretion in a human lung epithelial cell line (A549). Therefore, we established RSV persistence in these cells (A549per) and determined the levels of interleukin-8 mRNA by RT-PCR and of protein through ELISA. Interleukin-8 mRNA synthesis and protein secretion were continuously up-regulated in A549per cells during passages and in A549 cells that had been incubated with supernatants (cA549per) obtained from A549per passages. These results suggested that the enhancement of interleukin-8 was stimulated either by the presence of the RSV genome in the cell or by soluble mediator(s) induced by RSV, which, in turn, increased interleukin-8 mRNA synthesis and protein secretion. Soluble RSV F and G proteins were identified as mediators. Moreover, interleukin-8 enhancement was observed after 1-min incubation with the soluble mediators, thus suggesting that interleukin-8 up-regulation was triggered by receptor-ligand interaction.

Double-stranded RNA stimulates the expression of monocyte chemoattractant protein-1 in BEAS-2B bronchial epithelial cells

BEAS-2B bronchial epithelial cells were treated with polyinosinic-polycytidylic acid (poly IC), a synthetic double-stranded RNA (dsRNA) analog, and the expressions of monocyte chemoattractant protein-1 (MCP-1) mRNA and protein were analyzed by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay. Poly IC enhanced the expression of MCP-1 and release of mononuclear cell chemotactic activity, which were inhibited by dexamethasone pre-treatment. The poly IC-induced up-regulation of MCP-1 was blocked by 2-aminopurine, a specific inhibitor of dsRNA-dependent protein kinase, but not by nuclear factor (NF)-kappaB inhibitor SN50.

αEβ7 Expression on CD8+ T-Cells in COPD BAL Fluid and on TGF-β Stimulated T-Cells In Vitro

The airway inflammation in patients with COPD shows increased numbers of CD8+ T-cells. Until now few studies have shown any functional data indicating a role for these cells in the pathogenesis of COPD. This paper focuses on a subset of CD8+ T-cells present in human lung, the intra-epithelial lymphocytes expressing the integrin alphaEbeta7, and their presence in bronchoalveolar lavage fluid from COPD patients. In this study we demonstrate that 64-89% of the CD8+ T-cells in bronchoalveolar lavage fluid from COPD patients are positive for CD103, the alpha subunit of alphaEbeta7. We also present an in vitro system in which it is possible to differentiate peripheral T-cells into a phenotype resembling the one found in bronchoalveolar lavage fluid, i.e., CD8+ CD103+. In this in vitro system we demonstrate that, in addition to TGF-beta1, cell-to-cell interaction between the T-cell and an antigen-presenting cell represented here by the monocyte, is crucial for a rapid, high and sustained expression of CD103. The signal provided by the monocytes is shown to be mediated through LFA-1 on the T-cell. Furthermore, differentiation of CD8+ T-cells by TGF-beta1 and monocytes results in down regulation of INF-gamma, TNF-alpha and GM-CSF production. IL-8 production is, however, retained in the alphaEbeta7 expressing cells. We see this work as an initiation on the quest for a functional characterization of one of the different types of CD8+ T cells present in COPD. In the longer perspective we hope this can lead to an increased understanding of how these cells can contribute to the disease pathology.

Respiratory syncytial virus infection in elderly adults

Respiratory syncytial virus (RSV) infection is now recognised as a significant problem in elderly adults. Epidemiological evidence indicates the impact of RSV in older adults may be similar to non-pandemic influenza, both in the community and in long-term care facilities. Attack rates in nursing homes are approximately 5-10% per year with significant rates of pneumonia (10-20%) and death (2-5%). Estimates using US health care databases and viral surveillance results over a 9-year period indicate that RSV infection causes approximately 10,000 all-cause deaths annually among persons >64 years of age. In contrast, influenza A accounted for approximately 37,000 yearly deaths in the same age group. The clinical features of RSV infection may be difficult to distinguish from those of influenza but include nasal congestion, cough, wheezing and low-grade fever. Older persons with underlying heart and lung disease and immunocompromised patients are at highest risk for RSV infection-related pneumonia and death. Diagnosis of RSV infection in adults is difficult because viral culture and antigen detection are insensitive, presumably because of low viral titres. The combination of serology and reverse transcriptase polymerase chain reaction assay offers the best sensitivity and specificity for the diagnosis of RSV but unfortunately these techniques are not widely available; consequently, most adult RSV disease goes unrecognised. Although treatment of RSV infection in the elderly is largely supportive, early therapy with ribavirin and intravenous gamma-globulin improves survival in immunocompromised persons. An effective RSV vaccine has not yet been developed. Therefore, prevention of RSV is limited to standard infection control practices, such as hand washing and the use of gowns and gloves.

Role of antimicrobial agents in the management of exacerbations of COPD

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are a common occurrence and characterize the natural history of the disease. Over the past decade, new knowledge has substantially enhanced our understanding of the pathogenesis, outcome and natural history of AECOPD. The exacerbations not only greatly reduce the quality of life of these patients, but also result in hospitalization, respiratory failure, and death. The exacerbations are the major cost drivers in consumption of healthcare resources by COPD patients. Although bacterial infections are the most common etiologic agents, the role of viruses in COPD exacerbations is being increasingly recognized. The efficacy of antimicrobial therapy in acute exacerbations has established a causative role for bacterial infections. Recent molecular typing of sputum isolates further supports the role of bacteria in AECOPD. Isolation of a new strain of Haemophilus influenzae, Moraxella catarrhalis, or Streptococcus pneumoniae was associated with a considerable risk of an exacerbation. Lower airway bacterial colonization in stable patients with COPD instigates airway inflammation, which leads to a protracted self-perpetuating vicious circle of progressive lung damage and disease progression. A significant proportion of patients treated for COPD exacerbation demonstrate incomplete recovery, and frequent exacerbations contribute to decline in lung function. The predictors of poor outcome include advanced age, significant impairment of lung function, poor performance status, comorbid conditions and history of previous frequent exacerbations requiring antibacterials or systemic corticosteroids. These high-risk patients, who are likely to harbor organisms resistant to commonly used antimicrobials, should be identified and treated with antimicrobials with a low potential for failure. An aggressive management approach in complicated exacerbations may reduce costs by reducing healthcare utilization and hospitalization.

Acute bronchitis: state of the art diagnosis and therapy

In managing acute bronchitis, pneumonia or an exacerbation of underlying chronic bronchitis should be excluded. Simple bronchitis is best treated symptomatically while an exacerbation of chronic bronchitis can be treated with antibiotics. Broad spectrum antibiotics are appropriate in selected patients.