Biopsy neutrophilia, neutrophil chemokine and receptor gene expression in severe exacerbations of chronic obstructive pulmonary disease

Increased cytokine response of rhinovirus-infected airway epithelial cells in chronic obstructive pulmonary disease

RATIONALE

Airway inflammation is a central feature of chronic obstructive pulmonary disease (COPD). COPD exacerbations are often triggered by rhinovirus (RV) infection.

OBJECTIVES

We hypothesized that airway epithelial cells from patients with COPD maintain a proinflammatory phenotype compared with control subjects, leading to greater RV responses.

METHODS

Cells were isolated from tracheobronchial tissues of 12 patients with COPD and 10 transplant donors. Eight patients with COPD had severe emphysema, three had mild to moderate emphysema, and one had no emphysema. All had moderate to severe airflow obstruction, and six met criteria for chronic bronchitis or had at least one exacerbation the previous year. Cells were grown at air-liquid interface and infected with RV serotype 39. Cytokine and IFN expression was measured by ELISA. Selected genes involved in inflammation, oxidative stress, and proteolysis were assessed by focused gene array and real-time polymerase chain reaction.

MEASUREMENTS AND MAIN RESULTS

Compared with control subjects, cells from patients with COPD demonstrated increased mRNA expression of genes involved in oxidative stress and the response to viral infection, including NOX1, DUOXA2, MMP12, ICAM1, DDX58/RIG-I, STAT1, and STAT2. COPD cells showed elevated baseline and RV-stimulated protein levels of IL-6, IL-8/CXCL8, and growth-related oncogene-alpha/CXCL1. COPD cells demonstrated increased viral titer and copy number after RV infection, despite increased IL-29/IFN-lambda1, IL-28A/IFN-lambda2, and IFN-inducible protein-10/CXCL10 protein levels. Finally, RV-infected COPD cultures showed increased mRNA expression of IL28A/IFNlambda2, IL29/IFNlambda1, IFIH1/MDA5, DDX58/RIG-I, DUOX1, DUOX2, IRF7, STAT1, and STAT2.

CONCLUSIONS

Airway epithelial cells from patients with COPD show higher baseline levels of cytokine expression and increased susceptibility to RV infection, despite an increased IFN response.

Serum IP-10 as a biomarker of human rhinovirus infection at exacerbation of COPD

BACKGROUND

Human rhinovirus (HRV) is the most frequent virus associated with COPD exacerbations. Viral infections increase exacerbation severity and likelihood of hospitalization. As ease of sampling blood makes serum a more practical marker than sputum, we investigated whether changes in serum interferon-gamma-inducible protein 10 (IP-10) from baseline to exacerbation were higher in airway HRV-positive exacerbations and whether IP-10 levels related to HRV load.

METHODS

One hundred thirty-six patients with COPD and 70 controls were included over 2 years and 72 exacerbations sampled. HRV positivity and load were determined by reverse transcriptase-polymerase chain reaction in nasopharyngeal swabs and/or sputum at baseline and exacerbation. IP-10 was measured by enzyme-linked immunosorbent assay in serum and compared with HRV load.

RESULTS

At baseline, serum IP-10 was higher in patients with COPD than controls; medians were 149.4 pg/mL (103-215) and 111.7 pg/mL (82-178), P = .02. The presence of HRV at baseline did not increase IP-10: patients with COPD, 166.9 pg/mL (110-240) and 149.4 pg/mL (103-215), P = .30; controls, 136.4 pg/mL (77-204) and 111.7 pg/mL (82-178), P = .53. IP-10 increased significantly from baseline to exacerbation in HRV-positive exacerbations: 154.9 pg/mL (114.0-195.1) to 207.5 pg/mL (142.1-333.5), P = .009. There was no change in IP-10 between baseline and exacerbation in HRV-negative exacerbations: 168.3 pg/mL (94.3-249.8) and 175.6 pg/mL (107.2-290.4), P = .49. At exacerbation, IP-10 correlated with sputum viral load: rho = 0.48; P = .02. In receiver operating characteristics analysis, the combination of IP-10 and coryzal symptoms gave an area under the curve of 0.82 (95% CI, 0.74-0.90).

CONCLUSIONS

IP-10 increases from baseline to exacerbation in HRV-positive exacerbations and correlates with sputum HRV load. Serum IP-10 may be useful as a novel marker for these events.

Is there a role for antiinflammatory treatment in COPD?

By definition, chronic obstructive pulmonary disease (COPD) is associated with an abnormal inflammatory response of affected lungs. Therefore, the search for an effective anti-inflammatory therapy for this debilitating disease is intense. However, to date, there is no such anti-inflammatory treatment for COPD. While there are some modest effects of inhaled corticosteroids on selected clinical endpoints in COPD, it remains to be proven that the observed effects are due to changes in the underlying inflammation, in particular since relevant clinical endpoints of COPD can be significantly improved by treatments not targeting inflammation. Therefore, it appears justified to reconsider the present knowledge about any linkage of local and systemic inflammation and clinical features of COPD, including lung function, exacerbations, disease progression, and mortality. Any such link needs to be carefully established before future anti-inflammatory therapies for COPD are developed and investigated in clinical trials, in particular since proof-of-concept trials aiming merely at inflammatory markers in COPD may not be predictive of clinical success or failure. The present review summarizes current knowledge about the role of inflammation in COPD, and critically analyzes results from clinical trials with inhaled corticosteroids and phosphodiesterase-4 inhibitors in COPD, the two classes of putative antiinflammatory agents with the richest body of evidence from controlled studies.

Airway inflammation and anti-protease defences rapidly improve during treatment of an acute exacerbation of COPD

Background and objective:  There are few data on the short‐term natural history of airway inflammation during severe episodes of acute exacerbation of COPD (AECOPD). An observational study was performed to determine how rapidly conventional treatment improves airway inflammation in patients admitted to hospital with AECOPD.

Methods:  Twenty‐four consecutive patients with AECOPD were recruited and changes in sputum inflammatory indices were assessed after 2 and 4 days of treatment. The primary end‐points included presence of bacteria and viruses, changes in sputum total cell counts (TCC) and polymorphonuclear leukocyte (PMN) differential counts, and levels of secretory leukocyte protease inhibitor (SLPI), IL‐8 and TNF‐α.

Results:  All patients received oral corticosteroids and 17 (71%) were also treated with oral antibiotics. A bacterial or viral pathogen was isolated from 12 patients (50%), and Aspergillus fumigatus was isolated from one. A positive bacterial culture was associated with increased sputum TCC and PMN count (P < 0.05), as well as higher levels of IL‐8 and TNF‐α (P < 0.05), and a trend towards lower sputum SLPI levels (P = 0.06). Sputum PMN numbers fell by 70% within the first 48 h of admission (P < 0.05), accompanied by an increase in sputum SLPI (P < 0.001) and reductions in the levels of TNF‐α (P < 0.005) and IL‐8 (P = 0.06), with no further significant change at 4 days.

Conclusions:  Conventional treatment for severe AECOPD is associated with rapid reduction of neutrophilic inflammation and improvement in anti‐protease defences.

Human rhinovirus-induced epithelial production of CXCL10 is dependent upon IFN regulatory factor-1

Human rhinovirus (HRV) infections are associated with exacerbations of lower-airway diseases. HRV-induced production of proinflammatory chemokines, such as CXCL10, from infected airway epithelial cells may play a role in the pathogenesis of exacerbations. We have previously shown that the MAP/ERK kinase (MEK) pathway selectively down-regulates HRV-16-induced epithelial production of CXCL10 by modulating nuclear translocation and/or binding of IFN regulatory factor (IRF)-1 with the CXCL10 promoter. Using primary human bronchial epithelial cells (HBEs) and the BEAS-2B bronchial epithelial cell line, we have further evaluated the role of IRF-1 in HRV-16-induced epithelial CXCL10 production. We demonstrate that HRV-16 induced the expression of both IRF-1 mRNA and protein in a time-dependent manner. Interestingly, MEK1 pathway inhibition with PD98059 or U0126 significantly enhanced HRV-16-induced IRF-1 mRNA levels in BEAS-2B cells and HBEs, although IRF-1 protein expression was only enhanced in HBEs. Using short interfering RNA (siRNA), we both inhibited HRV-16-induced IRF-1 expression and reduced nuclear translocation and/or binding of IRF-1 to the CXCL10 promoter. Knockdown of IRF-1 also led to a significant reduction in HRV-16-induced CXCL10 production, confirming that IRF-1 is directly involved in HRV-16-induced CXCL10 expression in epithelial cells. Moreover, pronounced IRF-1 knockdown abrogated the enhancement of CXCL10 normally induced by inhibitors of the MEK1 pathway. Phosphatase experiments indicate that IRF-1 binding to the CXCL10 promoter is not dependent upon its phosphorylation state. We conclude that HRV-16-induced CXCL10 production is dependent upon IRF-1, and that the MEK1 pathway-dependent suppression of CXCL10 expression is also mediated via effects on IRF-1.

Oxymetazoline inhibits and resolves inflammatory reactions in human neutrophils

The nasal decongestant oxymetazoline (OMZ) exhibits anti-oxidative and anti-inflammatory properties (I. Beck-Speier et al., J Pharmacol Exp Ther. 2006;316:842-851). In a follow up study, we hypothesized that OMZ generates pro-resolving lipoxins being paralleled by production of immune-modulating prostaglandin E(2) (PGE(2)) and anti-inflammatory 15(S)-hydroxy-eicosatetraenoic acid [15(S)-HETE] and depletion of pro-inflammatory leukotriene B(4) (LTB(4)). Human neutrophils (PMN) were chosen as the cellular system. The effect of OMZ on these parameters as well as on respiratory burst activity and oxidative stress marker 8-isprostane was analyzed in unstimulated and co-stimulated PMN by ultrafine carbon particles (UCP) or opsonized zymosan (OZ), respectively. In unstimulated cells, OMZ induced formation of PGE(2), 15(S)-HETE, and LXA(4). The levels of LTB(4) and 8-isoprostane were not affected, whereas respiratory burst activity was drastically inhibited. In UCP- and OZ-stimulated control cells, all parameters were elevated. Here, OMZ maintained the increased levels of PGE(2), 15(S)-HETE, and LXA(4), but substantially suppressed levels of LTB(4) and 8-isoprostane and inhibited the respiratory burst activity. These findings suggest a switch from the pro-inflammatory eicosanoid class LTB(4) to the pro-resolving LXA(4). Since LXA(4) is most relevant in returning inflamed tissue to homeostasis, OMZ is postulated to terminate rhinitis-related inflammation, thus contributing to shortening of disease duration.

The cytokine network in chronic obstructive pulmonary disease

Multiple cytokines play a role in the orchestration of inflammation in inflammatory airway diseases, such as chronic obstructive pulmonary disease, through the recruitment, activation and survival of inflammatory cells. Lymphokines secreted from T cells regulate the pattern of inflammation, whereas proinflammatory cytokines amplify and perpetuate the inflammatory response. Multiple chemokines recruit inflammatory cells from the circulation into the lungs and many growth factors maintain this inflammation and lead to characteristic structural changes in the airways. There are several therapeutic approaches that target cytokine-mediated inflammation in chronic obstructive pulmonary disease, but blocking specific cytokines may not provide clinical benefit, whereas broad-spectrum anti-inflammatory approaches are more likely to be clinically effective.

Oxidative stress enhances toll-like receptor 3 response to double-stranded RNA in airway epithelial cells

Virus infections are a major cause of chronic obstructive pulmonary disease (COPD) exacerbations. Recently, Toll-like receptor 3 (TLR3) has been demonstrated to react to double-stranded RNA (dsRNA) and to be involved in the immune responses after viral infections. In the present study, we examined whether oxidative stress, which is involved in the pathogenesis of COPD, enhances the responses of TLR3 in airway epithelial cells. The effect of hydrogen peroxide (H(2)O(2)) on the release of IL-8 from BEAS-2B cells and primary human bronchial epithelial cells after stimulation with polyinosine-polycytidylic acid [poly(I:C)], a synthetic analog of viral dsRNA and a ligand for TLR3, and the signal transduction were examined. One hundred to 150 muM H(2)O(2) significantly potentiated the release of IL-8 from the epithelial cells after stimulation with 10 microg/ml poly(I:C). The H(2)O(2)-augmented IL-8 release was inhibited by treatment with N-acetylcysteine. One hundred micromoles of H(2)O(2) enhanced the translocation of nuclear factor (NF)-kappaB p65, but not that of interferon regulatory factor-3 (IRF-3), into the nucleus and the NF-kappaB DNA binding activity after poly(I:C) stimulation, which effect was inhibited not by the silencing of IRF-3 but by MG132, a proteasome inhibitor, or dexamethasone. One hundred micromoles of H(2)O(2) potentiated the TLR3 expression on the airway epithelial cells treated with poly(I:C). These data suggest that oxidative stress augments the response of TLR3 in airway epithelial cells via NF-kappaB and that this effect might be partly mediated by the enhancement of TLR3 expression. Modulation of this pathway may be a therapeutic target for viral-induced exacerbations of COPD.

Dual PDE3/4 inhibitors as therapeutic agents for chronic obstructive pulmonary disease

Phosphodiesterase (PDE)4, and to a lesser extent, PDE3/4 inhibitors have attracted considerable interest as potential therapeutic agents for diseases including chronic obstructive pulmonary disease. Indeed, ibudilast and theophylline are utilized clinically, and roflumilast is in late-stage clinical development. Unfortunately, however many PDE4 and dual PDE3/4 inhibitors have failed in early development due to low therapeutic ratios. The majority of these compounds are however orally administered and non-selective for either PDE3(A, B) or PDE4(A, B, C, D) subtypes. Developing an inhaled dual PDE3/4 inhibitor with subtype specificity may represent one strategy to improve the therapeutic index. Indeed combined inhibition of PDE3 and PDE4 inhibitor has additive and synergistic anti-inflammatory and bronchodilatory effects versus inhibition of either PDE3 or PDE4 alone. Given that synergy has been seen in terms of efficacy end points, an obvious concern is that synergy may also be observed in side effects. Interestingly, however, no synergy or additive effects with a combination of a PDE3 and PDE4 inhibitor in a cardiomyocyte assay were observed. This review will summarize the rationale for developing an inhaled dual PDE3/4 inhibitor, as a treatment for chronic obstructive pulmonary disease together with recent advances in trying to understand the pathogenesis of PDE inhibitor-induced mesenteric vasculitis (a key potential dose-limiting side effect of these agents), highlighting potential early and sensitive predictive biomarkers.

Selective transcriptional down-regulation of human rhinovirus-induced production of CXCL10 from airway epithelial cells via the MEK1 pathway

Human rhinovirus (HRV) infections can trigger exacerbations of lower airway diseases. Infection of airway epithelial cells induces production of a number of proinflammatory chemokines that may exacerbate airway inflammation, including CXCL10, a chemoattractant for type 1 lymphocytes and NK cells. Primary human bronchial epithelial cells and the BEAS-2B human bronchial epithelial cell line were used to examine the role of MAPK pathways in HRV-16-induced production of CXCL10. Surprisingly, PD98059 and U0126, two inhibitors of the MEK1/2-ERK MAPK pathway, significantly enhanced HRV-16-induced CXCL10 mRNA and protein. This enhancement was not seen with IFN-beta-induced production of CXCL10. Studies using small interfering RNA revealed that knockdown of MEK1, but not MEK2, was associated with enhanced HRV-induced CXCL10 production. Promoter construct studies revealed that PD98059 and U0126 enhanced HRV-16-induced transcriptional activation of CXCL10. HRV-16-induced promoter activation was regulated by two NF-kappaB binding sites, kappaB1 and kappaB2, and by an IFN-stimulated response element. Inhibitors of the MEK1/2-ERK pathway did not alter HRV-16-induced activation of tandem repeat kappaB1 or kappaB2 constructs, nor did they alter HRV-16-induced nuclear translocation/binding of NF-kappaB to either kappaB1 or kappaB2 recognition sequences. Furthermore, PD98059 and U0126 did not alter phosphorylation or degradation of IkappaBalpha. In contrast, inhibitors of the MEK1/2-ERK pathway, and small interfering RNA knockdown of MEK1, enhanced nuclear translocation/binding of IFN regulatory factor (IRF)-1 to the IFN-stimulated response element recognition sequence in HRV-16 infected cells. We conclude that activation of MEK1 selectively down-regulates HRV-16-induced expression of CXCL10 via modulation of IRF-1 interactions with the gene promoter in human airway epithelial cells.

Change in inflammation in out-patient COPD patients from stable phase to a subsequent exacerbation

Background

Inflammation increases during exacerbations of COPD, but only a few studies systematically assessed these changes. Better identification of these changes will increase our knowledge and potentially guide therapy, for instance by helping with quicker distinction of bacterially induced exacerbations from other causes.

Aim

To identify which inflammatory parameters increase during COPD exacerbations compared to stable disease, and to compare bacterial and non-bacterial exacerbations.

Methods

In 45 COPD patients (37 male/8 female, 21 current smokers, mean age 65, FEV₁ 52% predicted, pack years 38) sputum was collected during a stable phase and subsequently during an exacerbation.

Results

Sputum total cell counts (9.0 versus 7.9 × 10⁶/mL), eosinophils (0.3 versus 0.2 × 106/mL), neutrophils (6.1 versus 5.8 × 10⁶/mL), and lymphocytes (0.07 versus 0.02 × 10⁶/mL) increased significantly during an exacerbation compared to stable disease. A bacterial infection was demonstrated by culture in 8 sputum samples obtained during an exacerbation. These exacerbations had significantly increased sputum total cell and neutrophil counts, leukotriene-B4, myeloperoxidase, interleukin-8 and interleukin-6, and tumor necrosis factor-α (TNF-α) levels, and were also associated with more systemic inflammation compared to exacerbations without a bacterial infection. Sputum TNF-α level during an exacerbation had the best test characteristics to predict a bacterial infection.

Conclusion

Sputum eosinophil, neutrophil, and lymphocyte counts increase during COPD exacerbations. The increase in systemic inflammation during exacerbations seems to be limited to exacerbations caused by bacterial infections of the lower airways. Sputum TNF-α is a candidate marker for predicting airway bacterial infection.

The cytokine network in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are very common inflammatory diseases of the airways. They both cause airway narrowing and are increasing in incidence throughout the world, imposing enormous burdens on health care. Cytokines play a key role in orchestrating the chronic inflammation and structural changes of the respiratory tract in both asthma and COPD and have become important targets for the development of new therapeutic strategies in these diseases.

CXCR2 antagonists for the treatment of pulmonary disease

Chemokines have long been implicated in the initiation and amplification of inflammatory responses by virtue of their role in leukocyte chemotaxis. The expression of one of the receptors for these chemokines, CXCR2, on a variety of cell types and tissues suggests that these receptors may have a broad functional role under both constitutive conditions and in the pathophysiology of a number of acute and chronic diseases. With the development of several pharmacological, immunological and genetic tools to study CXCR2 function, an important role for this CXC chemokine receptor subtype has been identified in chronic obstructive pulmonary disease (COPD), asthma and fibrotic pulmonary disorders. Interference with CXCR2 receptor function has demonstrated different effects in the lungs including inhibition of pulmonary damage induced by neutrophils (PMNs), antigen or irritant-induced goblet cell hyperplasia and angiogenesis/collagen deposition caused by lung injury. Many of these features are common to inflammatory and fibrotic disorders of the lung. Clinical trials evaluating small molecule CXCR2 antagonists in COPD, asthma and cystic fibrosis are currently underway. These studies hold considerable promise for identifying novel and efficacious treatments of pulmonary disorders.

Targeting the NF-kappaB pathway in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease are inflammatory lung disorders responsible for significant morbidity and mortality worldwide. While the importance of allergic responses in asthma is well known, respiratory viral and bacterial infections and pollutants especially cigarette smoke are important factors in the pathogenesis of both diseases. Corticosteroid treatment remains the first preference of treatment in either disease, however these therapies are not always completely effective, and are associated with side effects and steroid resistance. Due to such limitations, development of new treatments represents a major goal for both the pharmaceutical industry and academic researchers. There are now excellent reasons to promote NF-kappaB signalling intermediates and Rel family proteins as potential therapeutic targets for both asthma and chronic obstructive pulmonary disease. This notion is supported by the fact that much of the underlying inflammation of both diseases independent of stimuli, is mediated at least in part, by NF-kappaB mediated signalling events in several cell types. Also, a range of inhibitors of NF-kappaB signalling intermediates are now available, including DNA oligonucleotides and DNA-peptide molecules that act as NF-kappaB decoy sequences, small molecule inhibitors such as IKK-beta inhibitors, and proteasome inhibitors affecting NF-kappaB signalling, that have either shown promise in animal models or have begun clinical trials in other disorders. This review will focus on the role of NF-kappaB in both diseases, will discuss its suitability as a target, and will highlight recent key studies that support the potential of NF-kappaB as a therapeutic target in these two important inflammatory lung diseases.

Airways inflammation and treatment during acute exacerbations of COPD

INTRODUCTION

Inflammation is a core feature of acute chronic obstructive pulmonary disease (COPD) exacerbations. It is important to focus on inflammation since it gives insight into the pathological changes causing an exacerbation, thereby possibly providing directions for future therapies which modify inflammation.

OBJECTIVES

To provide a cell-by-cell overview of the inflammatory processes during COPD exacerbations. To evaluate cell activation, and cytokine production, cellular interactions, damaging effects of inflammatory mediators to tissue, and the relation to symptoms at the onset of COPD exacerbations. To speculate on future therapeutic options to modify inflammation during COPD exacerbations.

RESULTS

During COPD exacerbations, there is increased airway wall inflammation, with pathophysiological influx of eosinophils, neutrophils, and lymphocytes. Although links have been suggested between the increase in eosinophils and lymphocytes and a viral etiology of the exacerbation, and between the increase in neutrophils and a bacterial aetiology, these increases in both inflammatory cell types are not limited to the respective aetiologies and the underlying mechanisms remain elusive.

CONCLUSION

Further research is required to fully understand the inflammatory mechanisms in the onset and development of COPD exacerbations. This might make inflammatory pathway-specific intervention possible, resulting in a more effective treatment of COPD exacerbations with fewer side effects.

Salmeterol with fluticasone enhances the suppression of IL-8 release and increases the translocation of glucocorticoid receptor by human neutrophils stimulated with cigarette smoke

The combination of inhaled corticosteroids and long-acting beta2-adrenoceptor agonists is increasingly used in chronic obstructive pulmonary disease (COPD). Recently, we have demonstrated that combination of salmeterol and fluticasone propionate (FP) additionally suppress the production of IL-8 by human monocyte. In this study, the molecular mechanism behind the effectiveness of this combination therapy is investigated in human neutrophils. Human neutrophils were preincubated with salmeterol or FP or the combination. The amount of interleukin-8 (IL-8), elastase and matrix metalloproteinases (MMP)-2 and -9 releases, and reactive oxygen species (ROS) generation and expression of MAP kinase phosphatase (MKP-1) and glucocorticoid receptor (GR) were determined. Cigarette smoke medium (CSM) induces an increased expression of CXC receptors and the production of ROS that may explain the strong production of IL-8 by neutrophils. The expression of CXC receptors, the production of ROS, and the release of elastase and MMP-2 and -9 were not influenced by salmeterol, FP, or the combination. Interestingly, the combination therapy had an additive suppressive effect on the CSM-induced production of IL-8. The latter could be explained by an increased mRNA expression of MKP-1, the GR and an increased translocation of the GR to the nucleus. This leads eventually to suppression of both the NF-kappaB and MAPK pathways and, hence, to less IL-8 production by the neutrophil. These data are in support for the use of a combination therapy in COPD patients.

Inhaled and systemic corticosteroids in chronic obstructive pulmonary disease

Systemic and local inflammation is central to the pathophysiology of chronic obstructive pulmonary disease (COPD). Increased levels of inflammation have been linked to a more progressive course in COPD and have been shown to be present during an exacerbation. Decreases in inflammatory cytokines, C-reactive protein, and inflammatory cells have been observed with corticosteroid use, suggesting a possible mechanism for a therapeutic benefit of steroids. No available data support the routine use of systemic corticosteroids in stable COPD; however, short courses during exacerbations are likely to improve length of hospitalization, lung function, and relapse rate. Inhaled corticosteroids (ICS) decrease the rate of exacerbation and may improve the response to bronchodilators and decrease dyspnea in stable COPD. No study shows that ICS reduce the loss of lung function; however, recent data suggest a possible survival benefit when combined with long-acting beta agonists. There are limited data on the use of ICS in the treatment of acute exacerbations of COPD, and its role in this setting must be more clearly defined. The empiric use of systemic corticosteroids perioperatively represents another area of uncertainty. The role of pharmacogenetics in the metabolism of corticosteroids in COPD is evolving but may be partially responsible for the observed variability in patient responsiveness. The potential benefits of systemic or inhaled corticosteroid use must be weighed against the risk of known toxicities.

Viral infections in patients with chronic obstructive pulmonary disease

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease is a major cause of morbidity and mortality worldwide. There is increasing evidence that implicates viral infections as a major risk factor for exacerbations of chronic obstructive pulmonary disease. Recent studies have attempted to better characterize the epidemiology of viral infections in chronic obstructive pulmonary disease, identify unique clinical manifestations of virus-associated exacerbations, and develop new diagnostic tools and treatments.

RECENT FINDINGS

Rhinovirus, the organism most often responsible for causing the common cold, is also the most common infectious cause of chronic obstructive pulmonary disease exacerbations. Coronavirus, influenza, respiratory syncytial virus, parainfluenza, adenovirus, and metapneumovirus are other important viral causes of chronic obstructive pulmonary disease exacerbations. These exacerbations can be severe with prolonged recovery times. Although PCR technology has dramatically increased the detection rate of viruses in patients with chronic obstructive pulmonary disease, it does not differentiate infection from colonization. The use of biomarkers represents an exciting new potential diagnostic tool that may lend new insights into the pathogenesis of viral infections in patients with chronic obstructive pulmonary disease.

SUMMARY

Despite strong epidemiologic evidence linking respiratory virus infection to exacerbations of chronic obstructive pulmonary disease, many of the cellular and molecular mechanisms by which viruses cause exacerbations remain undetermined. Future research efforts to understand these mechanisms would aid the development of novel therapeutics to reduce the morbidity and mortality of this disease.

Dendritic cells in chronic obstructive pulmonary disease: new players in an old game

Dendritic cells (DCs) are professional antigen-presenting cells responsible for immune homeostasis. In the lung's responses to tissue damage or infection, they initiate and orchestrate innate and adaptive immunity. There are immature and mature states and at least three phenotypic and functional subsets. DCs circulate in the blood and localize to mucosal surfaces in immature form where they act as sentinels, sampling constituents of the external environment that breach the epithelium. With internalization of antigen, they are activated, mature, and migrate to draining lymph nodes to induce the proliferation and regulate the balance of Th1/Th2 T cells or to induce a state of tolerance, the last dependent on maturation status, extent of cell surface costimulatory molecule expression, and cytokine release. Cigarette smoke has modulatory effects varying with species, dose, the location examined within the lung, and the marker or technique used to identify DCs. Healthy smokers (and smokers with asthma) have reduced numbers of large airway mature DCs. In chronic obstructive pulmonary disease, the number of immature DCs is increased in small airways, whereas in smokers with chronic obstructive pulmonary disease, the total number of DCs appears to be reduced in large airways. We hypothesize that the long-term effects of cigarette smoke include reduction of DC maturation and function, changes that favor repeated infection, increased exacerbation frequency, and the altered (CD8(+) T-cell predominant) pattern of inflammation associated with this progressive chronic disease.

Human rhinovirus 1B exposure induces phosphatidylinositol 3-kinase-dependent airway inflammation in mice

RATIONALE

Infection with rhinovirus (RV) triggers exacerbations of asthma and chronic obstructive lung disease.

OBJECTIVES

We sought to develop a mouse model of RV employing RV1B, a minor group serotype that binds to the low-density lipoprotein receptor.

METHODS

C57BL/6 mice were inoculated intranasally with RV1B, replication-deficient ultraviolet (UV)-irradiated RV1B, or RV39, a major group virus.

MEASUREMENTS AND MAIN RESULTS

Viral RNA was present in the lungs of RV1B-treated mice, but not in those exposed to UV-irradiated RV1B or RV39. Lung homogenates of RV-treated mice contained infectious RV 4 days after inoculation. RV1B exposure induced neutrophilic and lymphocytic airway inflammation, as well as increased lung expression of KC, macrophage-inflammatory protein-2, and IFN-alpha and IFN-beta. RV1B-exposed mice showed airway hyperresponsiveness 1 and 4 days after inoculation. UV-irradiated RV1B induced modest neutrophilic airway inflammation and hyperresponsiveness 1 day after exposure. Both RV1B and UV-irradiated RV1B, but not RV39, increased lung phosphorylation of Akt. Confocal immunofluorescence showed colocalization of RV1B and phospho-Akt in the airway epithelium. Finally, pretreatment with the phosphatidylinositol 3-kinase inhibitor LY294002 attenuated chemokine production and neutrophil infiltration.

CONCLUSIONS

We conclude that RV1B induces airway inflammation in vivo. Evidence is presented that viral replication occurs in vivo and is required for maximal responses. On the other hand, viral replication was not required for a subset of RV-induced responses, including neutrophilic inflammation, airway hyperresponsiveness, and Akt phosphorylation. Finally, phosphatidylinositol 3-kinase/Akt signaling is required for maximal RV1B-induced airway neutrophilic inflammation, likely via its essential role in virus internalization.

Modeling of asthma, COPD and cystic fibrosis in sheep

Sheep naturally allergic to Ascaris suum antigen have been used to study the pathophysiology of asthma and more recently allergic rhinitis, chronic obstructive pulmonary disease (COPD) and cystic fibrosis. The utility of the model as it relates to the study of these diseases is discussed.

Role of macrolide therapy in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a leading cause of death and disability worldwide. The Global Burden of Disease study has concluded that COPD will become the third leading cause of death worldwide by 2020, and will increase its ranking of disability-adjusted life years lost from 12th to 5th. Acute exacerbations of COPD (AECOPD) are associated with impaired quality of life and pulmonary function. More frequent or severe AECOPDs have been associated with especially markedly impaired quality of life and a greater longitudinal loss of pulmonary function. COPD and AECOPDs are characterized by an augmented inflammatory response. Macrolide antibiotics are macrocyclical lactones that provide adequate coverage for the most frequently identified pathogens in AECOPD and have been generally included in published guidelines for AECOPD management. In addition, they exert broad-ranging, immunomodulatory effects both in vitro and in vivo, as well as diverse actions that suppress microbial virulence factors. Macrolide antibiotics have been used to successfully treat a number of chronic, inflammatory lung disorders including diffuse panbronchiolitis, asthma, noncystic fibrosis associated bronchiectasis, and cystic fibrosis. Data in COPD patients have been limited and contradictory but the majority hint to a potential clinical and biological effect. Additional, prospective, controlled data are required to define any potential treatment effect, the nature of this effect, and the role of bronchiectasis, baseline colonization, and other cormorbidities.

Pathogen-directed therapy in acute exacerbations of chronic obstructive pulmonary disease

Acute exacerbations of chronic obstructive pulmonary disease (COPD) are important events in the natural history of this chronic lung disorder. These events can be caused by a large number of infectious and noninfectious agents and are associated with an increased local and systemic inflammatory response. Their frequency and severity have been linked to progressive deterioration in lung function and health status. Infectious pathogens ranging from viral to atypical and typical bacteria have been implicated in the majority of episodes. Most therapeutic regimens to date have emphasized broad, nonspecific approaches to bronchoconstriction and pulmonary inflammation. Increasingly, therapy that targets specific etiologic pathogens has been advocated. These include clinical and laboratory-based methods to identify bacterial infections. Further additional investigation has suggested specific pathogens within this broad class. As specific antiviral therapies become available, better diagnostic approaches to identify specific pathogens will be required. Furthermore, prophylactic therapy for at-risk individuals during high-risk times may become a standard therapeutic approach. As such, the future will likely include aggressive diagnostic algorithms based on the combination of clinical syndromes and rapid laboratory modalities to identify specific causative bacteria or viruses.

Aspects on pathophysiological mechanisms in COPD

Chronic obstructive pulmonary disease (COPD) is a condition which is characterized by irreversible airway obstruction due to narrowing of small airways, bronchiolitis, and destruction of the lung parenchyma, emphysema. It is the fourth most common cause of mortality in the world and is expected to be the third most common cause of death by 2020. The main cause of COPD is smoking but other exposures may be of importance. Exposure leads to airway inflammation in which a variety of cells are involved. Besides neutrophil granulocytes, macrophages and lymphocytes, airway epithelial cells are also of particular importance in the inflammatory process and in the development of emphysema. Cell trafficking orchestrated by chemokines and other chamoattractants, the proteinase-antiproteinase system, oxidative stress and airway remodelling are central processes associated with the development of COPD. Recently systemic effects of COPD have attracted attention and the importance of systemic inflammation has been recognized. This seems to have direct therapeutic implications as treatment with inhaled glucocorticosteroids has been shown to influence mortality. The increasing body of knowledge regarding the inflammatory mechanism in COPD will most likely have implications for future therapy and new drugs, specifically aimed at interaction with the inflammatory processes, are currently being developed.

COPD exacerbations: defining their cause and prevention

Exacerbations of chronic obstructive pulmonary disease (COPD) are episodes of worsening of symptoms, leading to substantial morbidity and mortality. COPD exacerbations are associated with increased airway and systemic inflammation and physiological changes, especially the development of hyperinflation. They are triggered mainly by respiratory viruses and bacteria, which infect the lower airway and increase airway inflammation. Some patients are particularly susceptible to exacerbations, and show worse health status and faster disease progression than those who have infrequent exacerbations. Several pharmacological interventions are effective for the reduction of exacerbation frequency and severity in COPD such as inhaled steroids, long-acting bronchodilators, and their combinations. Non-pharmacological therapies such as pulmonary rehabilitation, self-management, and home ventilatory support are becoming increasingly important, but still need to be studied in controlled trials. The future of exacerbation prevention is in assessment of optimum combinations of pharmacological and non-pharmacological therapies that will result in improvement of health status, and reduction of hospital admission and mortality associated with COPD.

A novel, orally active CXCR1/2 receptor antagonist, Sch527123, inhibits neutrophil recruitment, mucus production, and goblet cell hyperplasia in animal models of pulmonary inflammation

Sch527123 [2-hydroxy-N,N-dimethyl-3-[[2-[[1(R)-(5-methyl-2-furanyl)propyl]amino]-3,4-dioxo-1-cyclobuten-1-yl]amino]ben-zamide] is a potent, selective antagonist of the human CXCR1 and CXCR2 receptors (Gonsiorek et al., 2007). Here we describe its pharmacologic properties at rodent CXCR2 and at the CXCR1 and CXCR2 receptors in the cynomolgus monkey, as well as its in vivo activity in models demonstrating prominent pulmonary neutrophilia, goblet cell hyperplasia, and mucus production. Sch527123 bound with high affinity to the CXCR2 receptors of mouse (K(d) = 0.20 nM), rat (K(d) = 0.20 nM), and cynomolgus monkey (K(d) = 0.08 nM) and was a potent antagonist of CXCR2-mediated chemotaxis (IC(50) approximately 3-6 nM). In contrast, Sch527123 bound to cynomolgus CXCR1 with lesser affinity (K(d) = 41 nM) and weakly inhibited cynomolgus CXCR1-mediated chemotaxis (IC(50) approximately 1000 nM). Oral treatment with Sch527123 blocked pulmonary neutrophilia (ED(50) = 1.2 mg/kg) and goblet cell hyperplasia (32-38% inhibition at 1-3 mg/kg) in mice following the intranasal lipopolysaccharide (LPS) administration. In rats, Sch527123 suppressed the pulmonary neutrophilia (ED(50) = 1.8 mg/kg) and increase in bronchoalveolar lavage (BAL) mucin content (ED(50) =<0.1 mg/kg) induced by intratracheal (i.t.) LPS. Sch527123 also suppressed the pulmonary neutrophilia (ED(50) = 1.3 mg/kg), goblet cell hyperplasia (ED(50) = 0.7 mg/kg), and increase in BAL mucin content (ED(50) = <1 mg/kg) in rats after i.t. administration of vanadium pentoxide. In cynomolgus monkeys, Sch527123 reduced the pulmonary neutrophilia induced by repeat bronchoscopy and lavage (ED(50) = 0.3 mg/kg). Therefore, Sch527123 may offer benefit for the treatment of inflammatory lung disorders in which pulmonary neutrophilia and mucus hypersecretion are important components of the underlying disease pathology.

Cooperative effects of rhinovirus and TNF-{alpha} on airway epithelial cell chemokine expression

Rhinovirus (RV) infections trigger exacerbations of airways disease, but underlying mechanisms remain unknown. We hypothesized that RV and cytokines present in inflamed airways combine to induce augmented airway epithelial cell chemokine expression, promoting further inflammation. To test this hypothesis in a cellular system, we examined the combined effects of RV39 and TNF-alpha, a cytokine increased in asthma and chronic obstructive pulmonary disease, on airway epithelial cell proinflammatory gene expression. Costimulation of 16HBE14o- human bronchial epithelial cells and primary mucociliary-differentiated tracheal epithelial cells with RV and TNF-alpha induced synergistic increases in IL-8 and epithelial neutrophil attractant-78 production. Similar synergism was observed for IL-8 promoter activity, demonstrating that the effect is transcriptionally mediated. Whereas increases in ICAM-1 expression and viral load were noted 16-24 h after costimulation, cooperative effects between RV39 and TNF-alpha were evident 4 h after stimulation and maintained despite incubation with blocking antibody to ICAM-1 given 2 h postinfection or UV irradiation of virus, implying that effects were not solely due to changes in ICAM-1 expression. Furthermore, RV39 infection induced phosphorylation of ERK and transactivation of the IL-8 promoter AP-1 site, which functions as a basal level enhancer, leading to enhanced TNF-alpha responses. We conclude that RV infection and TNF-alpha stimulation induce cooperative increases in epithelial cell chemokine expression, providing a cellular mechanism for RV-induced exacerbations of airways disease.

Upper airway viral infections

Upper airway viral infections (URI) are a major cause of absence from school and work. Although morbidity is low in most of the subjects, the complications of URI, including otitis media, sinusitis and exacerbations of asthma and chronic obstructive pulmonary disease (COPD) have an enormous health impact. Despite the major health care consequences associated with these complications, our understanding of how URI trigger upper airway symptoms and cause exacerbations of lower airway diseases remains limited. This article reviews our current understanding of the pathogenesis of URI, and of viral exacerbations of asthma and COPD, and considers host defense parameters that may regulate susceptibility to disease exacerbations. We will also consider current and potential therapeutic approaches for the treatment of URI and their lower airway complications.

Interleukin-17A modulates human airway epithelial responses to human rhinovirus infection

Human rhinovirus (HRV) infections are associated with exacerbations of asthma and chronic obstructive pulmonary disease that are characterized by a selective neutrophil infiltration. IL-17A, a cytokine derived primarily from activated T cells, has been linked to neutrophilic inflammation of the airways. We hypothesized that IL-17A alters the response of HRV-infected epithelial cells to modulate airway inflammatory cell populations. IL-17A synergistically enhanced HRV-16-induced epithelial production of the neutrophil chemoattractant, IL-8, as well as human beta-defensin-2 (HBD-2), a chemoattractant for immature dendritic cells and memory T cells, but suppressed viral production of the eosinophil chemoattractant, RANTES. These effects were not due to alterations of viral uptake or replication by IL-17A. The synergy between HRV-16 and IL-17A for IL-8 protein production was both dose- and time-dependent. IL-8 induction by IL-17A or HRV-16, alone and in combination, was reduced by inhibitors of the p38 and p44/42 MAPK pathways. By contrast, induction of HBD-2 depended on the activation of the p38 and JNK pathways. The ability of IL-17A to synergistically enhance HRV-induced IL-8 is mediated posttranscriptionally, since IL-8 promoter activation by the combination of the two stimuli was merely additive, whereas the combination of IL-17A and HRV-16 led to stabilization of IL-8 mRNA. Similarly, stimulation of HBD-2 promoter constructs by the combination of IL-17A and HRV-16 was no more than the sum of the individual responses. Further studies are needed to examine HBD-2 mRNA stability. Taken together, these data represent the first demonstration that IL-17A can modify epithelial responses to HRV in a manner that would be expected to favor the recruitment of neutrophils, immature dendritic cells, and memory T cells to the airways.

CXCL5 overexpression is associated with late stage gastric cancer

PURPOSE

Chemokines play multiple roles in the development and progression of many different tumors. Our cDNA array data suggested that chemokine CXCL5 was upregulated in gastric cancer. Here, we analyzed CXCL5 protein expression in gastric cancer and investigated the clinical implications of CXCL5 upregulation.

METHODS

Immunostaining for CXCL5 was performed on gastric tissue microarrays of tissue specimens obtained by gastrectomy. The intensity of immunostaining in tumor tissue was considered strong when tumor tissue staining was more intense than in normal tissue; the intensity was null when staining was weaker in the tumor than in normal tissue; and the intensity was weak when staining was similar in both tissues. Serum CXCL5 levels and microvascular density in tumor tissue were measured by ELISA and monoclonal antibody to Factor VIII.

RESULTS

Strong CXCL5 expression correlated with tumor stage. CXCL5 expression did not correlate with T stage. However, N stage positively correlated with CXCL5 expression. Serum CXCL5 levels in late stage (IIIB, IV) gastric cancer patients were higher than in patients with benign conditions. Microvascular density was higher in tumors with strong CXCL5 expression, but the correlation with CXCL5 was not linear. Multiple logistic regression analyses showed that, compared to no or weak expression, strong expression of CXCL5 was a significant risk factor for high N stage (N2, N3).

CONCLUSIONS

CXCL5 overexpression was associated with late stage gastric cancer and high N stage. These results suggest a role for CXCL5 in the progression of gastric cancer, specifically in lymph node metastasis.

New molecular targets for the treatment of neutrophilic diseases

Increased neutrophils are a feature of airway inflammation in patients with chronic obstructive pulmonary disease and in some patients with asthma, particularly patients with more severe disease, during exacerbations and with cigarette smoking. Because neutrophilic inflammation may be detrimental, there are several new approaches to inhibiting neutrophilic inflammation. Neutrophilic inflammation is resistant or poorly responsive to corticosteroids, so different anti-inflammatory approaches are needed. Blocking neutrophil chemotactic factors such as leukotriene B(4) and IL-8 and related cysteine-X-cysteine chemokines by blocking receptor for leukotriene B(4) 1 and receptor for cysteine-X-cysteine chemokines 2 receptors is an approach that is currently being investigated. Other approaches include blocking adhesion molecules such as E-selectin. Inhibiting phosphodiesterase-4, nuclear factor-kappaB, or p38 mitogen-activated protein kinase is another approach that inhibits the production of cysteine-X-cysteine chemokines. Antioxidants, long-acting beta(2)-agonists, and activators of histone deacetylase may also be effective.

Bronchial mucosal inflammation and upregulation of CXC chemoattractants and receptors in severe exacerbations of asthma

BACKGROUND

A study was undertaken to test the hypothesis that severe exacerbations of asthma are characterised by increased bronchial mucosal neutrophilia associated with upregulation of neutrophil chemoattractant ligands and their specific cell surface receptors.

METHODS

Immunohistology and in situ hybridisation were applied to endobronchial biopsy specimens from three groups: (1) 15 patients admitted to hospital with a severe exacerbation of asthma (E-asthma), (2) 15 with stable asthma (S-asthma) and (3) 15 non-atopic and non-smoker surgical controls (NSC).

RESULTS

There were significantly more neutrophils and eosinophils in the epithelium and subepithelium of patients in the E-asthma group (median (range) neutrophils 7 (0-380) and 78 (10-898)/mm2, eosinophils 31 (0-167) and 60 (6-351)/mm2, p<or=0.01 compared with NSC: 0 (0-10, 0-7, 0-18 and 0-3)/mm2, respectively), resulting in similar final densities of eosinophils and neutrophils. With respect to neutrophil chemoattractants and receptors, counts of CXCL5, CXCL8, CXCR1 and CXCR2 mRNA-positive cells in the subepithelium of the E-asthma group were, respectively, 5, 4, 4 and 18 times greater (p<or=0.01) than those of the NSC group. In the E-asthma group, cells expressing CXCL5 or CXCR2 were eightfold and threefold more frequent than those expressing CXCL8 or CXCR1 mRNA, respectively (p<0.01). CXCL5 and CXCR2 in E-asthma were associated with the number of eosinophils (r=0.59 and 0.66, p<0.02 for both) rather than the number of neutrophils.

CONCLUSION

In severe exacerbations of asthma there is a bronchial mucosal neutrophilia, eosinophilia and upregulation of CXC chemoattractants and their receptors. CXCL5 and CXCR2 have an association with eosinophila only, and these represent potentially new targets for treatment in exacerbations of asthma.

Rhinovirus activates interleukin-8 expression via a Src/p110beta phosphatidylinositol 3-kinase/Akt pathway in human airway epithelial cells

Rhinovirus (RV) is responsible for the majority of common colds and triggers exacerbations of asthma and chronic obstructive lung disease. We have shown that RV serotype 39 (RV39) infection activates phosphatidylinositol 3 (PI 3)-kinase and the serine threonine kinase Akt minutes after infection and that the activation of PI 3-kinase and Akt is required for maximal interleukin-8 (IL-8) expression. Here, we further examine the contributions of Src and PI 3-kinase activation to RV-induced Akt activation and IL-8 expression. Confocal fluorescent microscopy of 16HBE14o- human bronchial epithelial cells showed rapid (10-min) colocalization of RV39 with Src, p85alpha PI 3-kinase, p110beta PI 3-kinase, Akt and Cit-Akt-PH, a fluorescent Akt pleckstrin homology domain which binds PI(3,4,5)P(3). The chemical Src inhibitor PP2 {4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo [3,4-d]pyrimidine} and the PI 3-kinase inhibitor LY294002 each inhibited Akt phosphorylation and the colocalization of RV39 with Akt. Digoxigenin-tagged RV coprecipitated with a Crosstide kinase likely to be Akt, and inhibition of Src blocked kinase activity. Digoxigenin-tagged RV39 colocalized with the lipid raft marker ceramide. In 16HBE14o- and primary mucociliary differentiated human bronchial epithelial cells, inhibition of Src kinase activity with the Src family chemical inhibitor PP2, dominant-negative Src (K297R), and Src small interfering RNA (siRNA) each inhibited RV39-induced IL-8 expression. siRNA against p110beta PI 3-kinase also inhibited IL-8 expression. These data demonstrate that, in the context of RV infection, Src and p110beta PI 3-kinase are upstream activators of Akt and the IL-8 promoter and that RV colocalizes with Src, PI 3-kinase, and Akt in lipid rafts.

How viral infections cause exacerbation of airway diseases

Exacerbations of asthma and COPD are major causes of morbidity, mortality, and health-care costs. Over the last decade, studies using new molecular diagnostic techniques have established that respiratory viruses are a major cause of exacerbations of both asthma and COPD. The most prevalent viruses detected during exacerbations are the rhinoviruses. Despite the burden of disease associated with exacerbations, little is known about the mechanisms of virus-induced exacerbations of airway diseases. Exacerbations are associated with increased airway inflammation in patients with both asthma and COPD, but many questions remain unanswered regarding the key inflammatory cells and mediators involved. Identifying the key inflammatory mediators involved in exacerbations holds the promise of developing diagnostic and prognostic markers of exacerbation. In addition, such studies can identify new therapeutic targets for the development of novel drugs for the prevention and treatment of exacerbations.

Chemokine receptors as therapeutic targets in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is an increasing global health problem for which there are no effective disease-modifying therapies. COPD involves chronic inflammation of small airways and lung parenchyma, with the recruitment of inflammatory cells. This inflammatory-cell trafficking is orchestrated by multiple chemokines, so the blockade of chemokine receptors with selective antagonists might be an effective anti-inflammatory strategy in this disease. Several studies support the implication of several chemokines and their receptors in COPD, including chemokine receptors CXCR2 and CXCR3, with small-molecule receptor antagonists that are in development being potential anti-inflammatory therapies. Such a pharmacological strategy would provide a mechanism with which to inhibit leukocyte recruitment and, hence, reduce the inflammatory profile in COPD, which is currently unaffected by pharmacotherapy.

Leukocyte navigation mechanisms as targets in airway diseases

Respiratory diseases, including asthma and chronic obstructive pulmonary disease, are among the most significant diseases in terms of their disabling effects and healthcare burden. A characteristic feature of almost all respiratory diseases is the accumulation and activation of inflammatory leukocytes in the lung or airway. Recent advances in the understanding of the molecules and intracellular signalling events controlling these processes are now translating to new therapeutic entities. In this article, the process of leukocyte accumulation is summarized, together with the preclinical and clinical evidence supporting the utility of the individual components of this process as targets for disease therapy.

Protein kinase R, IkappaB kinase-beta and NF-kappaB are required for human rhinovirus induced pro-inflammatory cytokine production in bronchial epithelial cells

Rhinovirus infections cause the majority of acute exacerbations of airway diseases such as asthma and chronic obstructive pulmonary disease, with increased pro-inflammatory cytokine production by infected bronchial epithelial cells contributing to disease pathogenesis. Theses diseases are a huge cause of morbidity worldwide, and contribute a major economic burden to healthcare costs. Current steroid based treatments are only partially efficient at controlling virus induced inflammation, which remains an unmet therapeutic goal. Although NF-kappaB has been implicated, the precise mechanisms of rhinovirus induction of pro-inflammatory gene expression in bronchial epithelial cells are unclear. We hypothesised that rhinovirus replication and generation of dsRNA was an important process of pro-inflammatory cytokine induction. Using pharmalogical (2-aminopurine and a new small molecule inhibitor) and genetic inhibition of the dsRNA binding kinase protein kinase R, striking inhibition of dsRNA (polyrIC) and rhinovirus induced CCL5, CXCL8 and IL-6 protein was observed. Using confocal microscopy, rhinovirus induced protein kinase R phosphorylation co-located with NF-kappaB p65 nuclear translocation. Focusing on CXCL8, both rhinovirus infection and dsRNA treatment required IkappaB kinase-beta for induction of CXCL8. Analysis of cis-acting sites in the CXCL8 promoter revealed that both rhinovirus infection and dsRNA treatment upregulated CXCL8 promoter activation via NF-kappaB and NF-IL6 binding sites. Together, the results demonstrate the importance of dsRNA in induction of pro-inflammatory cytokines by rhinoviruses, and suggest that protein kinase R is involved in NF-kappaB mediated gene transcription of pro-inflammatory cytokines via IkappaB kinase-beta. These molecules regulating rhinovirus induction of inflammation represent therapeutic targets.

H. influenzae potentiates airway epithelial cell responses to rhinovirus by increasing ICAM-1 and TLR3 expression

Rhinovirus (RV) is an important trigger of chronic obstructive pulmonary disease (COPD) exacerbations. In addition, respiratory viruses are more likely to be isolated in patients with a history of frequent exacerbations, suggesting that these patients are more susceptible to viral infection. To examine potential mechanisms for cooperative effects between bacterial and viral infection in COPD, we studied the responses of cultured human airway epithelial cells to nontypeable Hemophilus influenzae and RV. In both 16HBE14o- and primary mucociliary-differentiated cells, preincubation with H. influenzae enhanced RV serotype 39-induced protein expression of interleukin (IL)-8, epithelial-derived neutrophil attractant-78, and growth-related oncogene-alpha. H. influenzae infection also increased the binding of RV39 to cultured cells, as well as expression of intercellular adhesion molecule (ICAM)-1 and Toll-like receptor (TLR)-3, receptors for RV and dsRNA, respectively. Neutralizing antibody against tumor necrosis factor-alpha inhibited IL-8 expression induced by H. influenzae and RV39. Finally, siRNA against TLR3 attenuated RV-induced IL-8 expression. We conclude that H. influenzae infection increases airway epithelial cell ICAM-1 and TLR3 expression, leading to enhanced binding of RV and a potentiation of RV-induced chemokine release. These data provide a cellular mechanism by which H. influenzae infection may increase the susceptibility of COPD patients to RV-induced exacerbations.

A single nucleotide polymorphism in the CCL1 gene predicts acute exacerbations in chronic obstructive pulmonary disease

RATIONALE

Acute exacerbations (AEs) in chronic obstructive pulmonary disease (COPD) are a major cause of morbidity and mortality in COPD.

OBJECTIVES

The marked heterogeneity in the host defense mechanisms may be attributed to single nucleotide polymorphisms (SNPs) in the inflammatory chemokines that show enhanced expression in the airway of patients with COPD who experience AEs.

METHODS

We investigated four SNPs of the CCL11, CCL1, and CCL5 genes in relation to the frequency and severity of AEs in retrospective and prospective studies of a cohort of 276 male patients with COPD.

MEASUREMENTS AND MAIN RESULTS

In the 2-yr retrospective study , one SNP (National Center for Biotechnology Information SNP reference: rs2282691) in the predicted enhancer region of the CCL1 gene, encoding a chemotactic factor for a series of leukocytes, was significantly associated with the frequency of AEs in a dominant model (Fisher's exact test: odds ratio [OR], 2.70; 95% confidence interval [CI], 1.36-5.36; p=0.004; logistic regression: OR, 3.06; 95% CI, 1.46-6.41; p=0.003; and Kruskal-Wallis test: p=0.003). In the 30-mo prospective study, the "A" allele was a significant risk allele for the severity of AEs, with a gene-dosage effect (Kaplan-Meier method with log-rank test: AA vs. TT; log-rank statistic: 7.67, p=0.006; Cox proportional hazards regression method: OR, 5.93; 95% CI, 1.28-27.48; p=0.023). The electromobility shift assay showed that C/EBPbeta, a key transcriptional factor in response to pulmonary infections, binds to the "T" allele, but not to the "A" allele.

CONCLUSIONS

Variants in the CCL1 gene are associated with susceptibility to AEs through their potential implication in the host defense mechanisms against AEs.

Inflammatory cells in the airways in COPD

Airway inflammation is central to the pathogenesis of both airway remodelling and parenchymal destruction in chronic obstructive pulmonary disease (COPD). Neutrophils, macrophages, and CD8+ T lymphocytes have been implicated in a number of studies, but a detailed profile of disease-phenotype specific inflammation has yet to emerge. The heterogeneity of the disease has hindered data interpretation while extrapolation of the results of relatively non-invasive studies to the actual pathology found in the distal lung is difficult. Moreover, prominent studies have had frequently conflicting results. Further investigations are needed to marry the different clinical phenotypes of COPD to their respective inflammatory profiles in the airways and thus improve our understanding of the pathogenesis of the disease as a whole.

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.

Chronic obstructive pulmonary disease: histopathology, inflammation and potential therapies

Chronic obstructive pulmonary disease (COPD) is a major worldwide health burden with increasing morbidity, mortality and health care cost. It is a slowly progressive chronic inflammatory condition that affects the conducting airways (both large and small) and lung parenchyma. In COPD, inflammation is evident early on even in mild disease and increases with disease severity. Recent advances in our knowledge demonstrate, by comparison with asthma, the distinctive, "abnormal" or exaggerated inflammatory processes involved in the pathogenesis of COPD and thus identify novel therapeutic targets that could potentially impact on disease progression. The present review will focus on what is known of the abnormal inflammatory response of COPD in different regions of the conducting airways and lung. Novel, potentially promising approaches to therapy are presented.