Changes in bronchial inflammation during acute exacerbations of chronic bronchitis

Dipeptidyl peptidase 1 inhibition as a potential therapeutic approach in neutrophil-mediated inflammatory disease

Neutrophils have a critical role in the innate immune response to infection and the control of inflammation. A key component of this process is the release of neutrophil serine proteases (NSPs), primarily neutrophil elastase, proteinase 3, cathepsin G, and NSP4, which have essential functions in immune modulation and tissue repair following injury. Normally, NSP activity is controlled and modulated by endogenous antiproteases. However, disruption of this homeostatic relationship can cause diseases in which neutrophilic inflammation is central to the pathology, such as chronic obstructive pulmonary disease (COPD), alpha-1 antitrypsin deficiency, bronchiectasis, and cystic fibrosis, as well as many non-pulmonary pathologies. Although the pathobiology of these diseases varies, evidence indicates that excessive NSP activity is common and a principal mediator of tissue damage and clinical decline. NSPs are synthesized as inactive zymogens and activated primarily by the ubiquitous enzyme dipeptidyl peptidase 1, also known as cathepsin C. Preclinical data confirm that inactivation of this protease reduces activation of NSPs. Thus, pharmacological inhibition of dipeptidyl peptidase 1 potentially reduces the contribution of aberrant NSP activity to the severity and/or progression of multiple inflammatory diseases. Initial clinical data support this view. Ongoing research continues to explore the role of NSP activation by dipeptidyl peptidase 1 in different disease states and the potential clinical benefits of dipeptidyl peptidase 1 inhibition.

Analysis of Airway Thickening and Serum Cytokines in COPD Patients with Frequent Exacerbations: A Heart of the Matter

Background

Differences in lung function for Chronic Obstructive Pulmonary Disease (COPD) cause bias in the findings when identifying frequent exacerbator phenotype-related causes. The aim of this study was to determine whether computed tomographic (CT) biomarkers and circulating inflammatory biomarkers were associated with the COPD frequent exacerbator phenotype after eliminating the differences in lung function between a frequent exacerbator (FE) group and a non-frequent exacerbator (NFE) group.

Methods

A total of 212 patients with stable COPD were divided into a FE group (n=106) and a NFE group (n=106) according to their exacerbation history. These patients were assessed by spirometry, quantitative CT measurements and blood sample measurements during their stable phase. Univariate and multivariate logistic regression were used to assess the association between airway thickening or serum cytokines and the COPD frequent exacerbator phenotype. Receiver operating characteristic (ROC) curves were calculated for Pi10, WA%, IL-1β and IL-4 to identify frequent exacerbators.

Results

Compared with NFE group, FE group had a greater inner perimeter wall thickness of a 10 mm diameter bronchiole (Pi10), a greater airway wall area percentage (WA%) and higher concentrations of IL-1β and IL-4 (p<0.001). After adjusting for sex, age, BMI, FEV1%pred and smoking pack-years, Pi10, WA%, IL-β and IL-4 were independently associated with a frequent exacerbator phenotype (p<0.001). Additionally, there was an increase in the odds ratio of the frequent exacerbator phenotype with increasing Pi10, WA%, IL-4, and IL-1β (p for trend <0.001). The ROC curve demonstrated that IL-1β had a significantly larger calculated area under the curve (p < 0.05) than Pi10, WA% and IL-4.

Conclusion

Pi10, WA%, IL-4, and IL-1β were independently associated with the frequent exacerbator phenotype among patients with stable COPD, suggesting that chronic airway and systemic inflammation contribute to the frequent exacerbator phenotype.

Trial Registration

This trial was registered in Chinese Clinical Trial Registry (https://www.chictr.org.cn). Its registration number is ChiCTR2000038700, and date of registration is September 29, 2020.

Host-Derived Cytotoxic Agents in Chronic Inflammation and Disease Progression

At inflammatory sites, cytotoxic agents are released and generated from invading immune cells and damaged tissue cells. The further fate of the inflammation highly depends on the presence of antagonizing principles that are able to inactivate these host-derived cytotoxic agents. As long as the affected tissues are well equipped with ready-to-use protective mechanisms, no damage by cytotoxic agents occurs and resolution of inflammation is initiated. However, long-lasting and severe immune responses can be associated with the decline, exhaustion, or inactivation of selected antagonizing principles. Hence, cytotoxic agents are only partially inactivated and contribute to damage of yet-unperturbed cells. Consequently, a chronic inflammatory process results. In this vicious circle of permanent cell destruction, not only novel cytotoxic elements but also novel alarmins and antigens are liberated from affected cells. In severe cases, very low protection leads to organ failure, sepsis, and septic shock. In this review, the major classes of host-derived cytotoxic agents (reactive species, oxidized heme proteins and free heme, transition metal ions, serine proteases, matrix metalloproteases, and pro-inflammatory peptides), their corresponding protective principles, and resulting implications on the pathogenesis of diseases are highlighted.

Siraitia grosvenorii Extract Attenuates Airway Inflammation in a Murine Model of Chronic Obstructive Pulmonary Disease Induced by Cigarette Smoke and Lipopolysaccharide

We studied the activities of Siraitia grosvenorii extracts (SGE) on airway inflammation in a mouse model of chronic obstructive pulmonary disease (COPD) stimulated by cigarette smoke extract (CSE) and lipopolysaccharide (LPS), as well as in LPS-treated human bronchial epithelial cell line (BEAS-2B). SGE improved the viability of LPS-incubated BEAS-2B cells and inhibited the expression and production of inflammatory cytokines. SGE also attenuated the mitogen-activated protein kinase (MAPK)-nuclear factor-kappa B (NF-κB) signaling activated by LPS stimulation in BEAS-2B cells. In mice stimulated by CSE and LPS, we observed the infiltration of immune cells into the airway after COPD induction. SGE reduced the number of activated T cells, B cells, and neutrophils in bronchoalveolar fluid (BALF), lung tissue, mesenteric lymph node, and peripheral blood mononuclear cells, as well as inhibited infiltration into organs and mucus production. The secretion of cytokines in BALF and the expression level of pro-inflammatory cytokines, mucin 5AC, Transient receptor potential vanilloid 1, and Transient receptor potential ankyrin 1 in lung tissue were alleviated by SGE. In addition, to investigate the activity of SGE on expectoration, we evaluated phenol red secretions in the trachea of mice. SGE administration showed the effect of improving expectoration through an increase in phenol red secretion. Consequently, SGE attenuates the airway inflammatory response in CSE/LPS-stimulated COPD. These findings indicate that SGE may be a potential herbal candidate for the therapy of COPD.

How and when to manage respiratory infections out of hospital

Lower respiratory infections include acute bronchitis, influenza, community-acquired pneumonia, acute exacerbation of COPD and acute exacerbation of bronchiectasis. They are a major cause of death worldwide and often affect the most vulnerable: children, elderly and the impoverished. In this paper, we review the clinical presentation, diagnosis, severity assessment and treatment of adult outpatients with lower respiratory infections. The paper is divided into sections on specific lower respiratory infections, but we also dedicate a section to COVID-19 given the importance of the ongoing pandemic. Lower respiratory infections are heterogeneous entities, carry different risks for adverse events, and require different management strategies. For instance, while patients with acute bronchitis are rarely admitted to hospital and generally do not require antimicrobials, approximately 40% of patients seen for community-acquired pneumonia require admission. Clinicians caring for patients with lower respiratory infections face several challenges, including an increasing population of patients with immunosuppression, potential need for diagnostic tests that may not be readily available, antibiotic resistance and social aspects that place these patients at higher risk. Management principles for patients with lower respiratory infections include knowledge of local surveillance data, strategic use of diagnostic tests according to surveillance data, and judicious use of antimicrobials.

Imbalance between IL-36 receptor agonist and antagonist drives neutrophilic inflammation in COPD

Current treatments fail to modify the underlying pathophysiology and disease progression of chronic obstructive pulmonary disease (COPD), necessitating alternative therapies. Here, we show that COPD subjects have increased IL-36γ and decreased IL-36 receptor antagonist (IL-36Ra) in bronchoalveolar and nasal fluid compared to control subjects. IL-36γ is derived from small airway epithelial cells (SAEC) and further induced by a viral mimetic, whereas IL-36RA is derived from macrophages. IL-36γ stimulates release of the neutrophil chemoattractants CXCL1 and CXCL8, as well as elastolytic matrix metalloproteinases (MMPs) from small airway fibroblasts (SAF). Proteases released from COPD neutrophils cleave and activate IL-36γ thereby perpetuating IL-36 inflammation. Transfer of culture media from SAEC to SAF stimulated release of CXCL1, that was inhibited by exogenous IL-36RA. The use of a therapeutic antibody that inhibits binding to the IL-36 receptor (IL-36R) attenuated IL-36γ driven inflammation and cellular cross talk. We have demonstrated a mechanism for the amplification and propagation of neutrophilic inflammation in COPD and that blocking this cytokine family via a IL-36R neutralizing antibody could be a promising new therapeutic strategy in the treatment of COPD.

Influenza A Virus-Driven Airway Inflammation may be Dissociated From Limb Muscle Atrophy in Cigarette Smoke-Exposed Mice

Limb muscle dysfunction is a hallmark of Chronic Obstructive Pulmonary Disease (COPD) which is further worsened following a viral-induced acute exacerbation of COPD (AECOPD). An amplified airway inflammation underlies the aggravated respiratory symptoms seen during AECOPD, however, its contributory role to limb muscle dysfunction is unclear. The present study examined the impact of influenza A virus (IAV)-induced exacerbation on hind limb muscle parameters. Airway inflammation was established in male BALB/c mice by exposure to cigarette smoke (CS) for 8 weeks. Exacerbation was then induced via inoculation with IAV, and various lung and muscle parameters were assessed on day 3 (peak of airway inflammation) and day 10 (resolution phase) post-infection. IAV infection exacerbated CS-induced airway inflammation as evidenced by further increases in immune cell counts within bronchoalveolar lavage fluid. Despite no significant impact on muscle mass, IAV exacerbation worsened the force-generating capacity of the tibialis anterior (TA) muscle. Protein oxidation and myogenic disruption was observed in the TA following CS exposure, however, IAV exacerbation did not augment these detrimental processes. To further explore the contributory role of airway inflammation on myogenic signaling, cultured myotubes were exposed to conditioned medium (CM) derived from bronchial epithelial cells stimulated with polyinosinic:polycytidylic acid and cigarette smoke extract (CSE). Despite an amplified inflammatory response in the lung epithelial cells, the CM derived from these cells did not potentiate myogenic disruption in the C2C12 myotubes. In conclusion, our data suggest that certain parameters of limb muscle dysfunction seen during viral-induced AECOPD may be independent of airway inflammation.

Eosinopenia as a biomarker for antibiotic use in COPD exacerbations: protocol for a retrospective hospital-based cohort study

INTRODUCTION

The acute exacerbation of chronic obstructive pulmonary disease (AECOPD) has a seriously negative impact on patients' healths condition and disease progression. Bacterial infection is closely related to AECOPD, and antibiotics are frequently used in clinical practice. The lack of specific biomarkers for rational antibiotics use always leads to antibiotics abuse in chronic obstructive pulmonary disease (COPD) flare-ups. Eosinopenia has been considered to be related to increased bacterial load of potentially pathogenic organisms at the onset of COPD exacerbations. Therefore, this study aims to investigate whether eosinopenia could be used as a reference for the use of antibiotics in AECOPD.

METHODS AND ANALYSIS

In this study, a hospital-based retrospective cohort design will be adopted to analyse the clinical data of inpatients who are primarily diagnosed with AECOPD in West China Hospital of Sichuan University from 1 January 2010 to 31 December 2020. Relevant data will be extracted from the Clinical Big Data Platform for Scientific Research in West China Hospital, including demographic characteristics, blood eosinophil count, procalcitonin, C reactive protein, microbial cultivation, antibiotics use, length of hospital stay, non-invasive ventilation use, intensive care unit transfer and mortality, etc. The collected data will be described and inferred by corresponding statistical methods according to the data type and their distributions. Multiple binary logistic regression models will be used to analyse the relationship between blood eosinophil count and bacterial infection. The antibiotics use, and patient morbidity and mortality will be compared between patients with or without eosinopenia.

ETHICS AND DISSEMINATION

This study has been approved by the Biomedical Ethics Review Board of West China Hospital of Sichuan University (Approval No. 2020-1056). And the research results will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ChiCTR2000039379.

Exacerbations of Lung Disease in Alpha-1 Antitrypsin Deficiency

Alpha-1 antitrypsin deficiency (AATD) is an important risk factor for development of chronic obstructive pulmonary disease (COPD). Patients with AATD classically develop a different pattern of lung disease from those with usual COPD, decline faster and exhibit a range of differences in pathogenesis, all of which may be relevant to phenotype and/or impact of exacerbations. There are a number of definitions of exacerbation, with the main features being worsening of symptoms over at least 2 days, which may be associated with a change in treatment. In this article we review the literature surrounding exacerbations in AATD, focusing, in particular, on ways in which they may differ from such events in usual COPD, and the potential impact on clinical management.

Serum Amyloid A in Stable COPD Patients is Associated with the Frequent Exacerbator Phenotype

Background

We sought to determine whether circulating inflammatory biomarkers were associated with the frequent exacerbator phenotype in stable COPD patients ie, those with two or more exacerbations in the previous year.

Methods

Eighty-eight stable, severe, COPD patients (4 females) were assessed for exacerbation frequency, pulmonary function, fraction of expired nitric oxide (F_ENO); inflammatory variables were measured in venous blood. Logistic regression assessed associations between the frequent exacerbator phenotype and systemic inflammation.

Results

Compared with infrequent exacerbators, frequent exacerbators (n=10; 11.4%) had greater serum concentration (median (25th-75th quartile)) of serum amyloid A (SAA; 134 (84–178) vs 71 (38–116) ng/mL; P=0.024), surfactant protein D (SP-D; 15.6 (9.0–19.3) vs 8.5 (3.6–14.9) ng/mL; P=0.049) and interleukin-4 (IL-4; 0.12 (0.08–1.44) vs 0.03 (0.01–0.10) pg/mL; P=0.001). SAA, SP-D and IL-4 were not significantly correlated with FEV₁%predicted or FVC %predicted. After adjusting for sex, age, BMI, FEV₁/FVC and smoking pack-years, only SAA remained independently associated with the frequent exacerbator phenotype (OR 1.49[1.09–2.04]; P=0.012). The odds of being a frequent exacerbator was 18-times greater in the highest SAA quartile (≥124.1 ng/mL) than the lowest SAA quartile (≤44.1 ng/mL) (OR 18.34[1.30–258.81]; P=0.031), and there was a significant positive trend of increasing OR with increasing SAA quartile (P=0.008). For SAA, the area under the receiver operating characteristic curve was 0.721 for identification of frequent exacerbators; an SAA cut-off of 87.0 ng/mL yielded an 80% sensitivity and 61.5% specificity.

Conclusion

In stable COPD patients, SAA was independently associated with the frequent exacerbator phenotype, suggesting that SAA may be a useful serum biomarker to inform progression or management in COPD.

The clinical value of suPAR in diagnosis and prediction for patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis

BACKGROUND

Soluble urokinase-type plasminogen activator receptor (suPAR) is positively correlated with immune system activity. Inflammation can promote the development of chronic obstructive pulmonary disease (COPD). Therefore, this study conducted a systematic review and meta-analysis to assess the association between suPAR levels and the pathogenesis of COPD, and further assess the exact clinical value of suPAR in COPD.

METHODS

PubMed, Excerpt Medica Database (Embase), Web of Science (WOS), and Cochrane Library databases were searched for studies that reported the value of suPAR diagnosis for adult COPD patients.

RESULTS

A total of 11 studies were included, involving 4520 participants. Both COPD patients with predicted forced expiratory volume in 1 s (FEV1)⩾80% [weighted mean difference (WMD) = 320.25; 95% confidence interval (CI): 99.79-540.71] and FEV1 < 80% (WMD = 2950.74; 95% CI: 2647.06-3254.43) showed higher suPAR level. The sensitivity and specificity of suPAR for diagnosis of COPD were 87% and 79%, respectively, and AUC was 84%. This can not only effectively identify acute exacerbation of COPD (AECOPD) in a healthy population (WMD = 3114.77; 95% CI: 2814.66-3414.88), but also has the potential to distinguish AECOPD from stable COPD (WMD = 351.40; 95% CI: 215.88-486.93). There was a significant decrease of suPAR level after treatment [WMD = -1226.97; 95% CI: -1380.91- (-1073.03)].

CONCLUSION

suPAR as a novel biomarker has potential for early diagnosis of COPD and prediction of AECOPD. There is a potential correlation between the level of suPAR and the state of COPD, which may also indicate the early state and severity of COPD. When the suPAR level of COPD patients is further increased, the risk of acute exacerbation increases and should be highly valued. This also shows potential as a measure of treatment response, and as a guide to the clinical management in COPD. The reviews of this paper are available via the supplemental material section.

A Systematic Review and Meta-Analysis of Sputum Purulence to Predict Bacterial Infection in COPD Exacerbations

The 2020 Global Initiative for Obstructive Lung Disease (GOLD) Report highlights the importance of sputum purulence in the decision to prescribe antibiotics for acute exacerbations. The purpose of this systematic review and meta-analysis was to evaluate the strength of literature supporting inclusion of sputum purulence in criteria utilized to evaluate if antimicrobials are indicated in acute COPD exacerbation. A total of 6 observational studies met inclusion criteria for this meta-analysis. Sputum purulence was defined by visual assessment of color, either subjectively by providers and/or patients or by a colored chart, where green or yellow sputum was considered purulent. Four of the studies were primarily conducted in hospitalized patients, one in the emergency department, and one in the primary care setting. Five studies relied upon expectorated sputum and one used bronchoscopy to obtain sputum samples for bacterial cultures. Compared with mucoid sputum, purulent sputum had a significantly higher probability of positive bacterial culture results (RR = 2.14, 95%CI [1.25, 3.67], p = 0.006, moderate quality). For sensitivity analysis, after removal of studies losing 2 or more points from the New Castle-Ottawa scale, the effect value remained statistically significant. This systematic review and meta-analysis showed a moderate level of evidence that purulent sputum during COPD exacerbation, as defined by yellow or green color, is associated with a significantly higher probability of potentially pathogenic bacteria, supporting GOLD report and NICE recommendations.

Herbal Medication, Macmoondong Decoction, Attenuates LPS-Induced COPD in Small Airways via TGF-β, CCL-2, and CXCL1

Chronic obstructive pulmonary disease (COPD) is an incurable disease related to the respiratory system. A 2017 report by the World Health Organization stated that it was the third most common cause of death in 2015. Macmoondong decoction is a prescription that has been used widely in Korea for the treatment of respiratory diseases, but there have been few investigations into the therapeutic mechanism. To investigate the anti-COPD effect of macmoondong decoction, the animals were divided into five treatment groups: control; COPD-induced control; Spiriva; 150 mg/kg macmoondong decoction; and 1500 mg/kg macmoondong decoction. Changes typically observed in COPD, such as the populations of WBC and neutrophils in BALF, the level of IgE in serum, morphological changes, the DNA levels, and the protein expression of cytokines and chemokines (TGF-β, CCL-2, CXCL1, and CXCL11) in the pulmonary system, were evaluated. Macmoondong decoction inhibited the populations of WBC and neutrophils in BALF and the level of IgE in serum. Dose-dependent prevention of the pulmonary morphological changes, such as emphysema and airway fibrosis, was observed. Macmoondong decoction suppressed the expression of DNA and proteins related to the occurrence of COPD, such as TGF-β, CCL-2, CXCL1, and CXCL11. In particular, the expression of TGF-β, CCL-2, and CXCL1 was significantly suppressed by 1500 mg/kg macmoondong decoction treatment compared with Spiriva treatment. Macmoondong decoction exerted an anti-COPD effect, and the mechanism of its action may be the suppression of TGF-β, CCL-2, CXCL1, and CXCL11 expression, which occurred in a dose-dependent manner. The mechanism of action of macmoondong decoction may be the dose-dependent suppression of TGF-β, CCL-2, CXCL1, and CXCL11, with TGF-β, CCL-2, and CXCL1 as the potential key factors involved in COPD suppression.

Ginsenoside Rg3 ameliorates acute exacerbation of COPD by suppressing neutrophil migration

Acute Exacerbation of Chronic Obstructive Pulmonary Disease (AECOPD) is an irreversible inflammatory airways disease responsible for global health burden, involved with a complex condition of immunological change. Exacerbation-mediated neutrophilia is an important factor in the pathogenesis of cigarette smoke-induced AECOPD. Ginsenoside Rg3, a red-ginseng-derived compound, has multiple pharmacological properties such as anti-inflammatory and antitumor activities. Here, we investigated a protective role of Rg3 against AECOPD, focusing on neutrophilia. 14-week-cigarette smoke (CS) exposure and non-typeable Haemophilus inflenzae (NTHi) infection were used to establish the AECOPD murine model. Rg3 (10, 20, 40 mg/kg) was administered intragastrically from the 12th week of CS exposure before infection, and this led to improved lung function and lung morphology, and reduced neutrophilic inflammation, indicating a suppressive effect on neutrophil infiltration by Rg3. Further investigations on the mechanism of Rg3 on neutrophils were carried out using bronchial epithelial cell (BEAS-2B) and neutrophil co-culture and transepithelial migration model. Pre-treatment of neutrophils with Rg3 reduced neutrophil migration, which seemed to be the result of inhibition of phosphatidylinositol (PtdIns) 3-kinases (PI3K) activation within neutrophils. Thus, Rg3 could inhibit exacerbation-induced neutrophilia in COPD by negatively regulating PI3K activities in neutrophils. This study provides a potential natural drug against AECOPD neutrophil inflammation.

Procalcitonin and antibiotics in moderate-severe acute exacerbation of chronic obstructive pulmonary disease: to use or not to use

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Acute exacerbations of COPD (AECOPD) are major driver for healthcare utilization with each exacerbation begetting the next exacerbation. It is, therefore, important to treat each episode effectively to prevent the next. However, this can be challenging as AECOPD result from complex interactions between host, environment and infective agents. The benefits of starting antibiotics in AECOPD, which are not life-threatening (e.g. not requiring mechanical ventilation) or not complicated by pneumonia remain controversial.

RECENT FINDINGS

The use of procalcitonin to guide antibiotic therapy in AECOPD has gained interest in recent years. The main advantage of this approach is a safe reduction in antibiotic use in a large group of patients, which may potentially translate to several other benefits. These include reduced antibiotic-related side-effects, reduced risk of developing antibiotic-resistant organisms and cost savings. This approach is associated with no increase in mortality or morbidity such as treatment failure, re-admission, admission to ICU.

SUMMARY

Procalcitonin-guided antibiotic therapy in AECOPD is a promising and safe approach, which may be ready for the prime time.

Pseudomonas aeruginosa-derived flagellin stimulates IL-6 and IL-8 production in human bronchial epithelial cells: A potential mechanism for progression and exacerbation of COPD

Background and purpose of the study: Pseudomonas aeruginosa commonly colonizes the airway of patients with chronic obstructive pulmonary disease (COPD) and exacerbates their symptoms. P. aeruginosa carries flagellin that stimulates toll-like receptor (TLR)-5; however, the role of flagellin in the pathogenesis of COPD remains unclear. The aim of the study was to evaluate the mechanisms of the flagellin-induced innate immune response in bronchial epithelial cells, and to assess the effects of anti-inflammatory agents for treatment. Materials and methods: We stimulated BEAS-2B cells with P. aeruginosa-derived flagellin, and assessed mRNA expression and protein secretion of interleukin (IL)-6 and IL-8. We also used mitogen-activated protein kinases (MAPK) inhibitors to assess the signaling pathways involved in flagellin stimulation, and investigated the effect of clinically available anti-inflammatory agents against flagellin-induced inflammation. Results: Flagellin promoted protein and mRNA expression of IL-6 and IL-8 in BEAS-2B cells and induced phosphorylation of p38, ERK, and JNK; p38 phosphorylation-induced IL-6 production, while IL-8 production resulted from p38 and ERK phosphorylation. Fluticasone propionate (FP) and dexamethasone (DEX) suppressed IL-6 and IL-8 production in BEAS-2B cells, but clarithromycin (CAM) failed to do so. Conclusions: P. aeruginosa-derived flagellin-induced IL-6 and IL-8 production in bronchial epithelial cells, which partially explains the mechanisms of progression and exacerbation of COPD. Corticosteroids are the most effective treatment for the suppression of flagellin-induced IL-6 and IL-8 production in the bronchial epithelial cells.

CCSP counterbalances airway epithelial-driven neutrophilic chemotaxis

Club cell secretory protein (CCSP) knockout mice exhibit increased airway neutrophilia, as found in chronic obstructive pulmonary disease (COPD). We therefore investigated whether treating COPD airway epithelia with recombinant human CCSP (rhCCSP) could dampen exaggerated airway neutrophilia.

Control, smoker and COPD air–liquid interface (ALI) cultures exposed to cigarette smoke extract (CSE) were treated with and without rhCCSP. The chemotactic properties of the supernatants were assessed using Dunn chambers. Neutrophil chemotaxis along recombinant human interleukin 8 (rhIL8) gradients (with and without rhCCSP) was also determined. rhCCSP–rhIL8 interactions were tested through co-immunoprecipitation, Biacore surface plasmon resonance (SPR) andin silicomodelling. The relationship between CCSP/IL8 concentration ratios in the supernatant of induced sputum from COPD patientsversusneutrophilic airway infiltration assessed in lung biopsies was assessed.

Increased neutrophilic chemotactic activity of CSE-treated ALI cultures followed IL8 concentrations and returned to normal when supplemented with rhCCSP. rhIL8-induced chemotaxis of neutrophils was reduced by rhCCSP. rhCCSP and rhIL8 co-immunoprecipitated. SPR confirmed thisin vitrointeraction (equilibrium dissociation constant=8 µM).In silicomodelling indicated that this interaction was highly likely. CCSP/IL8 ratios in induced sputum correlated well with the level of small airway neutrophilic infiltration (r2=0.746, p<0.001).

CCSP is a biologically relevant counter-balancer of neutrophil chemotactic activity. These different approaches used in this study suggest that, among the possible mechanisms involved, CCSP may directly neutralise IL8.

[Correlation between expressions of myeloperoxidase and eosinophil cationic protein in sputum and clinical features of asthma-chronic obstructive pulmonary disease overlap]

OBJECTIVE

To observe the role of myeloperoxidase(MPO)and eosinophilic cationic protein(ECP)in the airway inflammation and their correlation with clinical feature in asthma-COPD overlap (ACO) patients.

METHODS

Twenty patients with COPD, 20 with asthma, 20 with ACO and 20 control subjects underwent pulmonary function test for measurement of forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), peak expiratory flow (PEF), and maximum midexpiratory flow (MMF_25/75). COPD assessment test (CAT) was used to evaluate the clinical symptoms of the patients with COPD and ACO. The asthma control test (ACT) was used to evaluate the asthma control in the patients with asthma and ACO. Induced sputum samples were collected from the subjects for analysis of neutrophil and eosinophil ratios, and enzyme-linked immunosorbent assay was used to determine the expression levels of MPO and ECP in the sputum.

RESULTS

No significant difference was observed in the CAT scores between ACO group and COPD group (P&gt; 0.05). Compared with the asthma group, the patients with ACO had significantly lower ACT scores and lower FEV₁, PEF and MMF_25/75 (P &lt; 0.05). The patients with ACO had significantly higher FVC and sputum eosinophil ratio than those with COPD (P &lt; 0.05), and a higher sputum neutrophil ratio than those with asthma (P &lt; 0.01). In ACO group, the MPO level in sputum was significantly higher than that in the asthma group (P &lt; 0.05), while sputum ECP level was significantly higher than that in both the asthma group and COPD group (P &lt; 0.05 or 0.01). In ACO group, sputum MPO level was positively correlated with sputum neutrophil ratio (r=0.8358, P &lt; 0.01) but was not correlated with CAT score or FEV₁ (P&gt; 0.05); sputum ECP level was positively correlated with sputum eosinophil ratio (r=0.4666, P &lt; 0.05) and was inversely correlated with ACT score (r=-0.4966, P &lt; 0.05) and FEV₁ (r=-0.4610, P &lt; 0.05).

CONCLUSIONS

Both neutrophilic and eosinophilic inflammations occur in the airway of patients with ACO, and their sputum ECP level is negatively correlated with asthma control and obstructive airflow limitation.

Cholinergic mechanisms in an organic dust model simulating an acute exacerbation in patients with COPD

Background

Exposure in a pig barn induces airway inflammation that has similarities with the response observed in acute exacerbations in COPD.

Methods

A total of 15 smokers with COPD and 15 healthy non-smokers were exposed for 2 hours in a pig barn (in vivo exposure). Symptoms were assessed, lung function measured, and blood and sputum samples taken before and after exposure. Blood neutrophils were isolated and stimulated ex vivo with dust from a pig barn and acetylcholine, and inflammatory markers were analyzed.

Results

In vivo exposure caused more symptoms and greater lung function fall in COPD patients than in controls. Baseline concentrations of MMP9, TIMP1, IL6, CXCL8, in sputum and neutrophil blood count were higher in COPD patients than in controls. In vivo exposure increased MMP9, TIMP1, IL6, CXCL8, TNFα, and LTB₄ in sputum and MMP9 and IL6 in blood, with no difference between the groups, and serum CRP increased more in COPD subjects. Expression of choline acetyltransferase and acetylcholinesterase on sputum and blood cells was similar in the groups and uninfluenced by in vivo exposure. Dust exposure ex vivo increased choline acetyltransferase expression in neutrophils, but the dust and acetylcholine response did not differ between the groups before and after in vivo exposure.

Conclusion

COPD patients exposed in a pig barn experience symptoms similar to those in acute exacerbations and lung function deterioration that is unrelated to bronchial responsiveness. Cholinergic mechanisms are involved in the inflammatory response to dust, with no difference between COPD and non-smokers.

Establishment of a chronic obstructive pulmonary disease mouse model based on the elapsed time after LPS intranasal instillation

Chronic obstructive pulmonary disease (COPD) was the 3rd leading cause of death in 2012 worldwide. It is particularly severe in the elderly, who are at risk of death by coughing, mucous hypersecretion, and finally breathlessness. Recently, anti-COPD drug development has increased, and many animal screening systems have been studied. Tobacco smoke animal models are the best known animal screening system, but have several preparation requirements, such as a tobacco smoke generator and a separate facility to prevent smoke release. Accordingly, we evaluated the properties of a lipopolysaccharide (LPS) murine model for COPD screening and the effect of the time elapsed from 0 to 72 hr after LPS intranasal instillation on various biomarkers of COPD severity, such as WBC and neutrophils in bronchoalveolar fluid (BALF), IgE in serum, histopathology in the lung, and cytokines (IL-8, TNF-α, IFN-γ, and TGF-β) and chemokines (CCL-2, CXCL1, CXCL9, CXCL10, and CXCL11) in the respiratory system. Although from 48 hr after LPS treatment several factors which could be evaluated as biomarkers for COPD establishment such as WBC and neutrophil in BALF, IgE in serum, cytokines (IL-8, TNF-α, and IFN-γ), and chemokines (CCL-2, CXCL1, CXCL9, CXCL10, and CXCL11) increased at 72 hr the increment of important factors for COPD establishment such as IgE, fibrosis in the lung, and cytokines (IL-8, TNF-α, and IFN-γ) was more clear. Based on our results, we concluded that the optimal time after LPS intranasal instillation is 72 hr.

An Increased Proportion of Apoptosis in CD4⁺ T Lymphocytes Isolated from the Peripheral Blood in Patients with Stable Chronic Obstructive Pulmonary Disease

BACKGROUND

The pathophysiology of chronic obstructive pulmonary disease (COPD) includes inflammation, oxidative stress, an imbalance of proteases and antiproteases and apoptosis which has been focused on lately. Abnormal apoptotic events have been demonstrated in both epithelial and endothelial cells, as well as in inflammatory cells including neutrophils and lymphocytes in the lungs of COPD patients. An increased propensity of activated T lymphocytes to undergo apoptosis has been observed in the peripheral blood of COPD patients. Therefore, the apoptosis of T lymphocytes without activating them was investigated in this study.

METHODS

Twelve control subjects, 21 stable COPD patients and 15 exacerbated COPD patients were recruited in the study. The T lymphocytes were isolated from the peripheral blood using magnetically activated cell sorting. Apoptosis of the T lymphocytes was assessed with flow cytometry using Annexin V and 7-aminoactinomycin D. Apoptosis of T lymphocytes at 24 hours after the cell culture was measured so that the T lymphocyte apoptosis among the control and the COPD patients could be compared.

RESULTS

Stable COPD patients had increased rates of CD4⁺ T lymphocyte apoptosis at 24 hours after the cell culture, more than the CD4⁺ T lymphocyte apoptosis which appeared in the control group, while the COPD patients with acute exacerbation had an amplified response of CD4⁺ T lymphocyte apoptosis as well as of CD8⁺ T lymphocyte apoptosis at 24 hours after the cell culture.

CONCLUSION

Stable COPD patients have more apoptosis of CD4⁺ T lymphocytes, which can be associated with the pathophysiology of COPD in stable conditions.

The levels of serum pro-calcitonin and high-sensitivity C-reactive protein in the early diagnosis of chronic obstructive pulmonary disease during acute exacerbation

The level of of procalcitonin (PCT) and high-sensitivity C-reactive protein (hs-CRP) in the acute exacerbation of COPD (AECOPD) was investigated. Total of 20 patients with acute exacerbation of COPD who were admitted to the Department of Respiratory Medicine, Binzhou Center Hospital in the period of October 2012 to April 2015 were enrolled in the AECOPD group. According to the color of the sputum, the patients with AECOPD were divided into purulent sputum group (n=8) and non-purulent sputum group (n=12). In addition, 15 healthy people from the outpatient medical center were also selected as healthy control group. The levels of serum PCT and hs-CRP in both groups were determined by chemiluminescence and immunoturbidimetry, respectively for the comparison analysis. The serum PCT concentration in AECOPD group was 2.07±5.57 ng/ml, while that in healthy control group was 0.21±0.17 ng/ml. Significant difference was found between serum PCT levels in the two groups (p<0.05). The serum concentration of hs-CRP in AECOPD group was 3.66±3.95 mg/l, which is significantly higher than that of the healthy control group (0.49±0.17) (p<0.001). In AECOPD group, the sensitivity of PCT, hs-CRP and white blood cell count was 75, 40 and 40%, respectively, while the specificity was 80, 100 and 100%, respectively, indicating that PCT has higher sensitivity than hs-CRP and white blood cell count (p<0.05). However, no significant difference was found in specificity among these three methods (p>0.05). PCT level of the patients in purulent sputum group was 3.72±8.80 ng/ml, while that of the patients in non-purulent sputum group was 0.97±1.06 ng/ml. The serum hs-CRP level of patients in purulent sputum group was 4.94±4.60 mg/l, while that of the patients in non-purulent sputum group was (2.80±3.38 mg/l). Both the above parameters showed no significant difference between the purulent sputum group and the non-purulent sputum group (p>0.05). In conclusion, serum PCT and hs-CRP levels can be used as auxiliary diagnosis index for acute exacerbation of COPD. Measurement of serum PCT and hs-CRP levels in patients with AECOPD may be helpful in guiding antibacterial drug therapy.

Patterns and characterization of COPD exacerbations using real-time data collection

INTRODUCTION

Patients with chronic obstructive pulmonary disease often experience exacerbations. These events are important as they are a major cause of morbidity and mortality. Recently, it has been increasingly recognized that patients may experience symptoms suggestive of an exacerbation but do not seek treatment, which are referred to as unreported or untreated exacerbations. Symptom diaries used in clinical trials have the benefit of identifying both treated and untreated exacerbation events.

METHODS

The Kamada study was a multicenter, double-blind randomized controlled trial of inhaled augmentation therapy in alpha-1 antitrypsin deficiency (AATD). A retrospective review of daily electronic symptom diary cards was undertaken from the two leading centers to identify symptomatic episodes consistent with a definition of an exacerbation. The aims were to explore the relationship between exacerbation events and classical "Anthonisen" symptoms and to characterize treated and untreated episodes.

RESULTS

Forty-six AATD patients with airflow obstruction and history of exacerbations were included in the analysis. Two hundred thirty-three exacerbation episodes were identified: 103 untreated and 130 treated. Untreated episodes were significantly shorter (median 6 days; interquartile range [IQR] 3-10 days) than the treated episodes (median 10 days; IQR 5-18.25 days: P<0.001). Using logistic regression analysis, Anthonisen type and length of dyspnea were significant predictors of the treatment of an exacerbation event.

CONCLUSION

Real-time electronic diary cards provide valuable information about the characterization of exacerbations. Untreated episodes are common and are significantly shorter in duration than the treated episodes. Dyspnea is the most important single Anthonisen symptom in the prediction and/or driver of treatment.

Asiatic acid inhibits pulmonary inflammation induced by cigarette smoke

Asiatic acid (AA) is one of the major components of Titrated extract of Centella asiatica (TECA), which has been reported to possess antioxidant and anti-inflammatory activities. The purpose of this study was to investigate the protective effect of AA on pulmonary inflammation induced by cigarette smoke (CS). AA significantly attenuated the infiltration of inflammatory cells in bronchoalveolar lavage fluid (BALF) of CS exposure mice. AA also decreased ROS production and NE activity, and inhibited the release of proinflammatory cytokines in BALF. AA reduced the recruitment of inflammatory cells and MCP-1 expression in lung tissue of CS exposure mice. AA also attenuated mucus overproduction, and decreased the activation of MAPKs and NF-kB in lung tissue. Furthermore, AA increased HO-1 expression and inhibited the reduced expression of SOD3 in lung tissue. These findings indicate that AA effectively inhibits pulmonary inflammatory response, which is an important process in the development of chronic obstructive pulmonary disease (COPD) via suppression of inflammatory mediators and induction of HO-1. Therefore, we suggest that AA has the potential to treat inflammatory disease such as COPD.

Review: Do we need new antibiotics for treating exacerbations of COPD?

Exacerbations may produce permanent impairment in lung function and health status in patients with COPD. Up to 70% of episodes have a bacterial etiology, being of mixed viral infection in some cases. The new, more active antibiotics have demonstrated better eradication of bacteria in the airways and, consequently, prolongation of the time to the next exacerbation. However, the ability of bacteria to develop resistance to the antibiotics currently used warrants novel research into new families of antimicrobials, and the adoption of new strategies such as the prevention of exacerbations, nebulized antibiotic treatment or the use of antibiotics in combination.

Increased metabolic activity of neutrophils in patients with chronic obstructive pulmonary disease

Aims:

To compare the metabolic activity of peripheral neutrophils in patients diagnosed with chronic obstructive pulmonary disease (COPD) with that of healthy, nonsmoking volunteers.

Materials and Methods:

Venous blood samples were taken from patients diagnosed with COPD as well as from healthy nonsmokers. Each sample was subjected to the nitro blue tetrazolium (NBT) test in which neutrophils exhibiting elevated metabolic activity were detected by light microscopy. The test was repeated after stimulation with Escherichia coli (E. coli) endotoxin with fresh samples. Neutrophils showing dye uptake were then counted in each case.

Results:

We found that the mean numbers of activated neutrophils without and with the addition of endotoxin were 19% and 23%, respectively, in the control group and 56% and 62%, respectively, in the test group. Two-sample t-test statistic revealed that there was a significant (P < 0.01) increase in neutrophilic metabolic activity in patients with COPD as compared to that in healthy volunteers. This significance remained even after stimulation using E. coli endotoxin.

Conclusion:

The results hint at a potentially relevant pathogenic mechanism in COPD related to the metabolic activity of neutrophils. By exhibiting enhanced metabolic activity, neutrophils in the COPD patients are more likely to be involved in damaging lung tissues.

Determinants of bacteriological outcomes in exacerbations of chronic obstructive pulmonary disease

Purpose

Changes in sputum microbiology following antibiotic treatment of acute exacerbations of chronic obstructive pulmonary disease (AECOPD), including patterns of bacteriological relapse and superinfection are not well understood. Sputum microbiology at exacerbation is not routinely performed, but pathogen presence and species are determinants of outcomes. Therefore, we determined whether baseline clinical factors could predict the presence of bacterial pathogens at exacerbation. Bacterial eradication at end of treatment (EOT) is associated with clinical resolution of exacerbation. We determined the clinical, microbiological and therapeutic factors that were associated with bacteriological eradication in AECOPD at EOT and in the following 8 weeks.

Methods

Sputum bacteriological outcomes (i.e., eradication, persistence, superinfection, reinfection) from AECOPD patients (N = 1352) who were randomized to receive moxifloxacin or amoxicillin/clavulanate in the MAESTRAL study were compared. Independent predictors of bacterial presence in sputum at exacerbation and determinants for bacteriological eradication were analyzed by logistic regression and receiver operating characteristic (ROC) analyses.

Results

Significantly greater bacteriological eradication with moxifloxacin was mainly driven by superior Haemophilus influenzae eradication (P = 0.002, EOT). Baseline clinical factors were a weak predictor of the presence of pathogens in sputum (AUC_ROC = 0.593). On multivariate analysis, poorer bacterial eradication was associated with antibiotic resistance (P = 0.0001), systemic steroid use (P = 0.0024) and presence of P. aeruginosa (P = 0.0282).

Conclusions

Since clinical prediction of bacterial presence in sputum at AECOPD is poor, sputum microbiological analysis should be considered for guiding antibiotic therapy in moderate-to-severe AECOPD, particularly in those who received concomitant systemic corticosteroids or are at risk for infection with antibiotic-resistant bacteria.

Electronic supplementary material

The online version of this article (doi:10.1007/s15010-015-0833-3) contains supplementary material, which is available to authorized users.

Using the Electronic Nose to Identify Airway Infection during COPD Exacerbations

BACKGROUND

The electronic nose (e-nose) detects volatile organic compounds (VOCs) in exhaled air. We hypothesized that the exhaled VOCs print is different in stable vs. exacerbated patients with chronic obstructive pulmonary disease (COPD), particularly if the latter is associated with airway bacterial infection, and that the e-nose can distinguish them.

METHODS

Smell-prints of the bacteria most commonly involved in exacerbations of COPD (ECOPD) were identified in vitro. Subsequently, we tested our hypothesis in 93 patients with ECOPD, 19 of them with pneumonia, 50 with stable COPD and 30 healthy controls in a cross-sectional case-controlled study. Secondly, ECOPD patients were re-studied after 2 months if clinically stable. Exhaled air was collected within a Tedlar bag and processed by a Cynarose 320 e-nose. Breath-prints were analyzed by Linear Discriminant Analysis (LDA) with "One Out" technique and Sensor logic Relations (SLR). Sputum samples were collected for culture.

RESULTS

ECOPD with evidence of infection were significantly distinguishable from non-infected ECOPD (p = 0.018), with better accuracy when ECOPD was associated to pneumonia. The same patients with ECOPD were significantly distinguishable from stable COPD during follow-up (p = 0.018), unless the patient was colonized. Additionally, breath-prints from COPD patients were significantly distinguished from healthy controls. Various bacteria species were identified in culture but the e-nose was unable to identify accurately the bacteria smell-print in infected patients.

CONCLUSION

E-nose can identify ECOPD, especially if associated with airway bacterial infection or pneumonia.

Antimicrobial proteins and peptides in human lung diseases: A friend and foe partnership with host proteases

Lung antimicrobial proteins and peptides (AMPs) are major sentinels of innate immunity by preventing microbial colonization and infection. Nevertheless bactericidal activity of AMPs against Gram-positive and Gram-negative bacteria is compromised in patients with chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF) and asthma. Evidence is accumulating that expression of harmful human serine proteases, matrix metalloproteases and cysteine cathepsins is markedely increased in these chronic lung diseases. The local imbalance between proteases and protease inhibitors compromises lung tissue integrity and function, by not only degrading extracellular matrix components, but also non-matrix proteins. Despite the fact that AMPs are somewhat resistant to proteolytic degradation, some human proteases cleave them efficiently and impair their antimicrobial potency. By contrast, certain AMPs may be effective as antiproteases. Host proteases participate in concert with bacterial proteases in the degradation of key innate immunity peptides/proteins and thus may play immunomodulatory activities during chronic lung diseases. In this context, the present review highlights the current knowledge and recent discoveries on the ability of host enzymes to interact with AMPs, providing a better understanding of the role of human proteases in innate host defense.

Correlation between decrease of CRP and resolution of airway inflammatory response, improvement of health status, and clinical outcomes during severe acute exacerbation of chronic obstructive pulmonary disease

Circulating C-reactive protein (CRP) plays an important role in mediating extra-pulmonary complications of chronic obstructive pulmonary disease (COPD). The aim of this study was to investigate the relationship between changes in high sensitivity (hs)-CRP levels and the resolution of airway inflammatory markers and clinical health status during the recovery period after an acute exacerbation of COPD (AECOPD). Consecutive patients hospitalized for AECOPD were recruited. Serum hs-CRP, airway inflammatory markers, and COPD Assessment Test (CAT) score were evaluated at admission prior to treatment and at days 4, 7, and 14. Adverse outcomes were recorded. The relationship between changes in airway inflammatory markers, CAT score, and hs-CRP during the recovery period was studied. A total of 135 patients were enrolled. Serum hs-CRP levels at admission of patients with adverse outcomes were marginally higher than those without an adverse outcome (7.6 [4.8, 16.7] vs. 6.6 [4.7, 9.3], p = 0.061). Compared with patients without cardiovascular complications, patients with cardiovascular complications had higher serum hs-CRP levels at admission (11.6 [6.7, 16.7] vs. 6.6 [4.4, 10.0], p = 0.001). Sputum neutrophils were positively correlated to hs-CRP at admission (r = 0.474, p < 0.001). A decreasing hs-CRP level was positively related to decreasing sputum neutrophils at day 4 and 7 (r = 0.455, p < 0.001; r = 0.504, p < 0.001, respectively). Significant correlations between decreasing hs-CRP and CAT at all time-points were noted. Hs-CRP may be useful in monitoring airway inflammation resolution and improvement of health status during AECOPD treatment.

Signaling network of lipids as a comprehensive scaffold for omics data integration in sputum of COPD patients

Chronic obstructive pulmonary disease (COPD) is a heterogeneous and progressive inflammatory condition that has been linked to the dysregulation of many metabolic pathways including lipid biosynthesis. How lipid metabolism could affect disease progression in smokers with COPD remains unclear. We cross-examined the transcriptomics, proteomics, metabolomics, and phenomics data available on the public domain to elucidate the mechanisms by which lipid metabolism is perturbed in COPD. We reconstructed a sputum lipid COPD (SpLiCO) signaling network utilizing active/inactive, and functional/dysfunctional lipid-mediated signaling pathways to explore how lipid-metabolism could promote COPD pathogenesis in smokers. SpLiCO was further utilized to investigate signal amplifiers, distributers, propagators, feed-forward and/or -back loops that link COPD disease severity and hypoxia to disruption in the metabolism of sphingolipids, fatty acids and energy. Also, hypergraph analysis and calculations for dependency of molecules identified several important nodes in the network with modular regulatory and signal distribution activities. Our systems-based analyses indicate that arachidonic acid is a critical and early signal distributer that is upregulated by the sphingolipid signaling pathway in COPD, while hypoxia plays a critical role in the elevated dependency to glucose as a major energy source. Integration of SpLiCo and clinical data shows a strong association between hypoxia and the upregulation of sphingolipids in smokers with emphysema, vascular disease, hypertension and those with increased risk of lung cancer.

Altered protease and antiprotease balance during a COPD exacerbation contributes to mucus obstruction

BACKGROUND

Proteases have been shown to degrade airway mucin proteins and to damage the epithelium impairing mucociliary clearance. There are increased proteases in the COPD airway but changes in protease-antiprotease balance and mucin degradation have not been investigated during the course of a COPD exacerbation. We hypothesized that increased protease levels would lead to mucin degradation in acute COPD exacerbations.

METHODS

We measured neutrophil elastase (NE) and alpha 1 protease inhibitor (A1-PI) levels using immunoblotting, and conducted protease inhibitor studies, zymograms, elastin substrate assays and cigarette smoke condensate experiments to evaluate the stability of the gel-forming mucins, MUC5AC and MUC5B, before and 5-6 weeks after an acute pulmonary exacerbation of COPD (n = 9 subjects).

RESULTS

Unexpectedly, mucin concentration and mucin stability were highest at the start of the exacerbation and restored to baseline after 6 weeks. Consistent with these data, immunoblots and zymograms confirmed decreased NE concentration and activity and increased A1-PI at the start of the exacerbation. After recovery there was an increase in NE activity and a decrease in A1-PI levels. In vitro, protease inhibitor studies demonstrated that serine proteases played a key role in mucin degradation. Mucin stability was further enhanced upon treating with cigarette smoke condensate (CSC).

CONCLUSION

There appears to be rapid consumption of secreted proteases due to an increase in antiproteases, at the start of a COPD exacerbation. This leads to increased mucin gel stability which may be important in trapping and clearing infectious and inflammatory mediators, but this may also contribute acutely to mucus retention.

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

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

Preclinical murine models of Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) is a major incurable global health burden and is the 4th leading cause of death worldwide. It is believed that an exaggerated inflammatory response to cigarette smoke causes progressive airflow limitation. This inflammation, where macrophages, neutrophils and T lymphocytes are prominent, leads to oxidative stress, emphysema, small airway fibrosis and mucus hypersecretion. Much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities and infectious (viral and bacterial) exacerbations (AECOPD). Comorbidities, defined as other chronic medical conditions, in particular skeletal muscle wasting and cardiovascular disease markedly impact on disease morbidity, progression and mortality. The mechanisms and mediators underlying COPD and its comorbidities are poorly understood and current COPD therapy is relatively ineffective. Thus, there is an obvious need for new therapies that can prevent the induction and progression of COPD and effectively treat AECOPD and comorbidities of COPD. Given that access to COPD patients can be difficult and that clinical samples often represent a "snapshot" at a particular time in the disease process, many researchers have used animal modelling systems to explore the mechanisms underlying COPD, AECOPD and comorbidities of COPD with the goal of identifying novel therapeutic targets. This review highlights the mouse models used to define the cellular, molecular and pathological consequences of cigarette smoke exposure and the recent advances in modelling infectious exacerbations and comorbidities of COPD.

Identifying a gene expression signature of frequent COPD exacerbations in peripheral blood using network methods

Background

Exacerbations of chronic obstructive pulmonary disease (COPD), characterized by acute deterioration in symptoms, may be due to bacterial or viral infections, environmental exposures, or unknown factors. Exacerbation frequency may be a stable trait in COPD patients, which could imply genetic susceptibility. Observing the genes, networks, and pathways that are up- and down-regulated in COPD patients with differing susceptibility to exacerbations will help to elucidate the molecular signature and pathogenesis of COPD exacerbations.

Methods

Gene expression array and plasma biomarker data were obtained using whole-blood samples from subjects enrolled in the Treatment of Emphysema With a Gamma-Selective Retinoid Agonist (TESRA) study. Linear regression, weighted gene co-expression network analysis (WGCNA), and pathway analysis were used to identify signatures and network sub-modules associated with the number of exacerbations within the previous year; other COPD-related phenotypes were also investigated.

Results

Individual genes were not found to be significantly associated with the number of exacerbations. However using network methods, a statistically significant gene module was identified, along with other modules showing moderate association. A diverse signature was observed across these modules using pathway analysis, marked by differences in B cell and NK cell activity, as well as cellular markers of viral infection. Within two modules, gene set enrichment analysis recapitulated the molecular signatures of two gene expression experiments; one involving sputum from asthma exacerbations and another involving viral lung infections. The plasma biomarker myeloperoxidase (MPO) was associated with the number of recent exacerbations.

Conclusion

A distinct signature of COPD exacerbations may be observed in peripheral blood months following the acute illness. While not predictive in this cross-sectional analysis, these results will be useful in uncovering the molecular pathogenesis of COPD exacerbations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-014-0072-y) contains supplementary material, which is available to authorized users.

Targeting TRP channels for chronic cough: from bench to bedside

Cough is currently the most common reason for patients to visit a primary care physician in the UK, yet it remains an unmet medical need. Current therapies have limited efficacy or have potentially dangerous side effects. Under normal circumstances, cough is a protective reflex to clear the lungs of harmful particles; however, in disease, cough can become excessive, dramatically impacting patients' lives. In many cases, this condition is linked to inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD), but can also be refractory to treatment and idiopathic in nature. Therefore, there is an urgent need to develop therapies, and targeting the sensory afferent arm of the reflex which initiates the cough reflex may uncover novel therapeutic targets. The cough reflex is initiated following activation of ion channels present on vagal sensory afferents. These ion channels include the transient receptor potential (TRP) family of cation-selective ion channels which act as cellular sensors and respond to changes in the external environment. Many direct activators of TRP channels, including arachidonic acid derivatives, a lowered airway pH, changes in temperature, and altered airway osmolarity are present in the diseased airway where responses to challenge agents which activate airway sensory nerve activity are known to be enhanced. Furthermore, the expression of some TRP channels is increased in airway disease. Together, this makes them promising targets for the treatment of chronic cough. This review will cover the current understanding of the role of the TRP family of ion channels in the activation of airway sensory nerves and cough, focusing on four members, transient receptor potential vanilloid (TRPV) 1, transient receptor potential ankyrin (TRPA) 1, TRPV4, and transient receptor potential melastatin (TRPM) 8 as these represent the channels where most information has been gathered with relevance to the airways. We will describe recent data and highlight the possible therapeutic utility of specific TRP channel antagonists as antitussives in the clinic.

Targeting pro-resolution pathways to combat chronic inflammation in COPD

Chronic obstructive pulmonary disease (COPD) is an inflammatory lung condition that is associated with irreversible airflow obstruction as a consequence of small airways disease, excessive mucus production and emphysema. Paradoxically, excessive inflammation fails to control microbial pathogens that not only colonise COPD airways, but also trigger acute exacerbations, which markedly increase inflammation underlying host tissue damage. Excessive production of leukocyte mobilising cytokines such as CXCL8 (IL-8) and leukotriene B4 (LTB4) in response to environmental stimuli (cigarette smoke and microbial products) are thought to maintain chronic inflammation, in conjunction with inefficient macrophage clearance of microbes and apoptotic neutrophils. In this perspective, we discuss an alternative view on why inflammation persists with a focus on why pro-resolution mediators such as lipoxin A4 (LXA4), D-series resolving and Annexin A1 fail to effectively switch off inflammation in COPD. These pro-resolving mediators converge on the G-protein coupled receptor, ALX/FPR2. This receptor is particularly relevant to COPD as the complex milieu of exogenous and host-derived mediators within the inflamed airways include agonists that potently activate ALX/FPR2, including Serum Amyloid A (SAA) and the cathelicidin, LL-37. There is emerging evidence to suggest that ALX/FPR2 can exist in alternative receptor conformations in an agonist-biased manner, which facilitates alternate functional receptor behaviors. Hence, the development of more stable pro-resolving analogs provides therapeutic opportunities to address ALX/FPR2 conformations to counteract pathogenic signaling and promote non-phlogistic clearance pathways essential for resolution of inflammation.

Is C-reactive protein testing useful to predict outcome in patients with acute bronchitis?

BACKGROUND

A recent clinical trial could not find differences between anti-inflammatory drugs, antibiotics and placebo in shortening the duration of symptoms in acute bronchitis.

OBJECTIVES

To investigate if C-reactive protein (CRP) concentrations at presentation are predictive of symptom resolution in these patients.

METHODS

We performed a secondary analysis of the data from a placebo-controlled, randomized clinical trial carried out in primary care. Patients from 18 to 70 years of age presenting a respiratory tract infection of <1 week of evolution, with cough as the predominant symptom and the presence of discoloured expectoration, were enrolled in the study. On the baseline visit, CRP was determined in capillary blood and a five-item symptom diary was given. Patients were followed up to 30 days. The main outcome measure was the number of days with persistent cough.

RESULTS

A total of 312 subjects fulfilled all the criteria for the efficacy analysis and had undergone the CRP test; of these, 56.4% presented a CRP value <8 mg/l and 76% presented <20 mg/l. There were no significant differences in the median duration of cough: 10 days among patients with CRP concentrations <8 mg/l [95% confidence interval (CI): 8-11 days], 11 days among those with concentrations ranging from 8 to 19 mg/l (95% CI: 8-16) and 11 days in those with CRP >20 mg/l (95% CI: 9-12) (P = 0.337).

CONCLUSION

Among patients with uncomplicated acute bronchitis and discoloured sputum, the CRP concentrations at presentation are not helpful for predicting symptom resolution.

Increased of exhaled breath condensate neutrophil chemotaxis in acute exacerbation of COPD

Background

Neutrophils have been involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). Underlying mechanisms of neutrophil accumulation in the airways of stable and exacerbated COPD patients are poorly understood. The aim of this study was to assess exhaled breath condensate (EBC) neutrophil chemotactic activity, the level of two chemoattractants for neutrophils (GRO-α and LTB4) during the course of an acute exacerbation of COPD (AECOPD).

Methods

50 ex smoking COPD patients (33 with acute exacerbation and 17 in stable disease) and 20 matched ex smoking healthy controls were compared. EBC was collected by using a commercially available condenser (EcoScreen®). EBC neutrophil chemotactic activity (NCA) was assessed by using Boyden microchambers. Chemotactic index (CI) was used to evaluate cell migration. LTB₄ and GROα levels were measured by a specific enzyme immunoassay in EBC.

Results

Stable COPD and outpatients with AECOPD, but not hospitalized with AECOPD, had raised EBC NCA compared to healthy subjects (p < 0.05 and p < 0.01 respectively). In outpatients with AECOPD EBC NCA significantly decreased 6 weeks after the exacerbation. Overall EBC NCA was weakly correlated with sputum neutrophil counts (r = 0.26, p < 0.05).

EBC LTB4 levels were increased in all groups of COPD compared to healthy subjects while GRO-α was only raised in patients with AECOPD. Furthermore, EBC LTB₄ and GRO-α significantly decreased after recovery of the acute exacerbation. Increasing concentrations (0.1 to 10 μg/mL) of anti- human GRO-α monoclonal antibody had no effect on EBC neutrophil chemotactic activity of 10 exacerbated COPD patients.

Conclusions

EBC NCA rose during acute exacerbation of COPD in ambulatory patients and decreased at recovery. While LTB4 seems to play a role both in stable and in exacerbated phase of the disease, the role of GRO-α as a chemotactic factor during AECOPD is not clearly established and needs further investigation.

Significance of the microbiome in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is one of few chronic disorders with rising mortality and morbidity. It is a highly prevalent disorder, characterized by highly heterogeneous clinical symptoms, health status, and disease progression. COPD is also characterized by an inflammatory/immune response that persists despite smoking cessation and varies by the patient population, method of assessment, and timing of measurement. Bacterial colonization or infection is ubiquitous in patients with COPD and, until recently, has been predominantly assessed using culture-based methodologies. This colonization has been believed to be biologically relevant. It has been estimated that more than 70% of the bacterial species on body surfaces cannot be cultured by standard techniques. As such, advanced culture-independent techniques have been developed that target bacterial genes, such as the 16S ribosomal RNA gene, that function as molecular chronometers. Application of these techniques in patients with COPD has suggested microbial diversity that varies by age, disease severity, and medication use. All of these data provide unique and rapidly evolving insight into the potential role of the respiratory microbiome in disease genesis and expression.

Transient receptor potential (TRP) channels in the airway: role in airway disease

Over the last few decades, there has been an explosion of scientific publications reporting the many and varied roles of transient receptor potential (TRP) ion channels in physiological and pathological systems throughout the body. The aim of this review is to summarize the existing literature on the role of TRP channels in the lungs and discuss what is known about their function under normal and diseased conditions. The review will focus mainly on the pathogenesis and symptoms of asthma and chronic obstructive pulmonary disease and the role of four members of the TRP family: TRPA1, TRPV1, TRPV4 and TRPM8. We hope that the article will help the reader understand the role of TRP channels in the normal airway and how their function may be changed in the context of respiratory disease.

Cytokine inhibition in the treatment of COPD

Cytokines play an important part in many pathobiological processes of chronic obstructive pulmonary disease (COPD), including the chronic inflammatory process, emphysema, and altered innate immune response. Proinflammatory cytokines of potential importance include tumor necrosis factor (TNF)-α, interferon-γ, interleukin (IL)-1β, IL-6, IL-17, IL-18, IL-32, and thymic stromal lymphopoietin (TSLP), and growth factors such as transforming growth factor-β. The current objectives of COPD treatment are to reduce symptoms, and to prevent and reduce the number of exacerbations. While current treatments achieve these goals to a certain extent, preventing the decline in lung function is not currently achievable. In addition, reversal of corticosteroid insensitivity and control of the fibrotic process while reducing the emphysematous process could also be controlled by specific cytokines. The abnormal pathobiological process of COPD may contribute to these fundamental characteristics of COPD, and therefore targeting cytokines involved may be a fruitful endeavor. Although there has been much work that has implicated various cytokines as potentially playing an important role in COPD, there have been very few studies that have examined the effect of specific cytokine blockade in COPD. The two largest studies that have been reported in the literature involve the use of blocking antibody to TNFα and CXCL8 (IL-8), and neither has provided benefit. Blocking the actions of CXCL8 through its CXCR2 receptor blockade was not successful either. Studies of antibodies against IL-17, IL-18, IL-1β, and TSLP are currently either being undertaken or planned. There is a need to carefully phenotype COPD and discover good biomarkers of drug efficacy for each specific target. Specific groups of COPD patients should be targeted with specific anticytokine therapy if there is evidence of high expression of that cytokine and there are features of the clinical expression of COPD that will respond.

Sputum myeloperoxidase in chronic obstructive pulmonary disease

Background

Airway inflammation, especially neutrophilic airway inflammation, is a cardinal pathophysiologic feature in chronic obstructive pulmonary disease (COPD) patients. The ideal biomarkers characterizing the inflammation might have important potential clinical applications in disease assessment and therapeutic intervention. Sputum myeloperoxidase (MPO) is recognized as a marker of neutrophil activity. The purpose of this meta-analysis is to determine whether sputum MPO levels could reflect disease status or be regulated by regular medications for COPD.

Methods

Studies were identified by searching PubMed, Embase, the Cochrane Database, CINAHL and http://www.controlled-trials.com for relevant reports published before September 2012. Observational studies comparing sputum MPO in COPD patients and healthy subjects or asthmatics, or within the COPD group, and studies comparing sputum MPO before and after treatment were all included. Data were independently extracted by two investigators and analyzed using STATA 10.0 software.

Results

A total of 24 studies were included in the meta-analysis. Sputum MPO levels were increased in stable COPD patients when compared with normal controls, and this increase was especially pronounced during exacerbations as compared with MPO levels during the stable state. Theophylline treatment was able to reduce MPO levels in COPD patients, while glucocorticoid treatment failed to achieve the same result.

Conclusion

Sputum MPO might be a promising biomarker for guiding COPD management; however, further investigations are needed to confirm this.

Disease 'activity', 'severity' and 'impact': interrelationships in COPD; is a measure of disease 'activity' the Holy Grail for COPD, or a variable impossible to quantify?

It is increasingly recognised that new measures of disease 'activity' for COPD are required, however the relationship between markers of disease 'activity', 'severity' and 'impact' though closely linked, is poorly understood. Additionally, while change in markers of disease 'severity' (e.g. change in FEV1) may be considered a marker of disease 'activity', these quantify a single aspect of disease 'activity' in COPD rather than measuring the overall disease process and this has stimulated the search for new biomarkers of COPD that reflect the 'activity' of the disease process. The ideal biomarker of disease 'activity' would be stable with respect to time since measurement at any time point would then relate to subsequent disease progression. This would allow the influence of a therapeutic intervention to be assessed early, facilitating both phase 2 and 3 clinical trials. Although a number of potential biomarkers of COPD disease 'activity' have been studied, to date none have been shown to conclusively relate to disease progression and the stability of underlying disease 'activity' therefore requires further consideration. Interestingly, while the variability of disease 'activity' of COPD is rarely mentioned in the current literature, and there is uncertainty whether 'activity' is constant or highly variable, there are clues from available data as discussed in the current article. Finally we consider how markers of disease 'activity', 'severity' and 'impact' may relate, which is of utmost importance in the ongoing search for new biomarkers in COPD and a greater understanding of the pathogenesis of the disease process.

Human rhinoviruses and severe respiratory infections: is it possible to identify at-risk patients early?

Molecular methods of viral screening have demonstrated that human rhinoviruses (HRVs) are associated with lower respiratory tract infections (LRTIs, including bronchiolitis and pneumonia), exacerbations of chronic pulmonary disease and the development of asthma. Patients with severe chronic diseases are at greater risk of developing major clinical problems when infected by HRVs, particularly if they are immunocompromised or have a chronic lung disease. Analysing the characteristics of HRVs does not provide any certainty concerning the risk of a poor prognosis and, although viremia seems to be associated with an increased risk of severe HRV infection, the available data are too scanty to be considered conclusive. However, a chest x-ray showing alveolar involvement suggests the potentially negative evolution of a bacterial superinfection. There is therefore an urgent need for more effective diagnostic, preventive and therapeutic measures in order to prevent HRV infection, and identify and treat the patients at highest risk.

Progranulin is a substrate for neutrophil-elastase and proteinase-3 in the airway and its concentration correlates with mediators of airway inflammation in COPD

Progranulin (PGRN) is an anti-inflammatory protein, yet its digestion by neutrophil-derived proteinases generates products that can stimulate epithelial cell lines to secrete the neutrophil chemoattractant interleukin (IL)-8. Because dysregulated neutrophilic inflammation is implicated in the pathophysiology of chronic obstructive pulmonary disease (COPD), the possible influence of PGRN and digestion products may be of relevance to understanding and treating inflammation in the disease. PGRN was measured in sputum sol-phase samples from patients with a clinical diagnosis of COPD and chronic sputum production in a clinically stable state; PGRN correlated negatively with bacterial load (colony-forming units/ml) ( r = −0.446, P = 0.003, n = 43) and markers of neutrophilic inflammation, including neutrophil elastase (NE, nM) ( r = −0.562, P = 0.008, n = 21) and proteinase-3 (PR3, nM) ( r = −0.515, P = 0.017, n = 21). Products of PGRN digestion were detected in sputum sol phase, and PGRN conversion activity in sputum sol phase was inhibited with the serine proteinase inhibitor α1-antitrypsin. Digested PGRN at concentrations likely to be present in the airways did not stimulate IL-8 secretion from normal human bronchial epithelial (NHBE) cells. Infection of NHBE cells with live Haemophilus influenzae significantly increased PGRN secretion compared with untreated cells ( P ≤ 0.001). The concentration of PGRN relates negatively to the amplified airway inflammation associated with bacterial colonization in clinically stable COPD. This relationship is driven by the proteolytic action of the neutrophil-derived proteinases NE and PR3; the products released by this action are unlikely to stimulate significant IL-8 secretion from epithelial cells in the airways.