Airway bacterial concentrations and exacerbations of chronic obstructive pulmonary disease

Assessing the Clinical and Functional Status of COPD Patients Using Speech Analysis During and After Exacerbation

Background

Chronic obstructive pulmonary disease (COPD) affects breathing, speech production, and coughing. We evaluated a machine learning analysis of speech for classifying the disease severity of COPD.

Methods

In this single centre study, non-consecutive COPD patients were prospectively recruited for comparing their speech characteristics during and after an acute COPD exacerbation. We extracted a set of spectral, prosodic, and temporal variability features, which were used as input to a support vector machine (SVM). Our baseline for predicting patient state was an SVM model using self-reported BORG and COPD Assessment Test (CAT) scores.

Results

In 50 COPD patients (52% males, 22% GOLD II, 44% GOLD III, 32% GOLD IV, all patients group E), speech analysis was superior in distinguishing during and after exacerbation status compared to BORG and CAT scores alone by achieving 84% accuracy in prediction. CAT scores correlated with reading rhythm, and BORG scales with stability in articulation. Pulmonary function testing (PFT) correlated with speech pause rate and speech rhythm variability.

Conclusion

Speech analysis may be a viable technology for classifying COPD status, opening up new opportunities for remote disease monitoring.

Beyond the organ: lung microbiome shapes transplant indications and outcomes

The lung microbiome plays a crucial role in the development of chronic lung diseases, which may ultimately lead to the need for lung transplantation. Also, perioperative results seem to be connected with altered lung microbiomes and its dynamic changes providing a possible target for optimizing short-term outcome after transplantation. A literature review using MEDLINE, PubMed Central and Bookshelf was performed. Chronic lung allograft dysfunction (CLAD) seems to be influenced and partly triggered by changes in the pulmonary microbiome and dysbiosis, e.g. through increased bacterial load or abundance of specific species such as Pseudomonas aeruginosa. Additionally, the specific indications for transplantation, with their very heterogeneous changes and influences on the pulmonary microbiome, influence long-term outcome. Next to composition and measurable bacterial load, dynamic changes in the allografts microbiome also possess the ability to alter long-term outcomes negatively. This review discusses the "new" microbiome after transplantation and the associations with direct postoperative outcome. With the knowledge of these principles the impact of alterations in the pulmonary microbiome in hindsight to CLAD and possible therapeutic implications are described and discussed. The aim of this review is to summarize the current literature regarding pre- and postoperative lung microbiomes and how they influence different lung diseases on their progression to failure of conservative treatment. This review provides a summary of current literature for centres looking for further options in optimizing lung transplant outcomes and highlights possible areas for further research activities investigating the pulmonary microbiome in connection to transplantation.

Similarity analyses of causative viruses for chronic obstructive pulmonary disease and asthma exacerbations : Author

BACKGROUND

The representativeness of cohort studies compared to nationwide data is a major concern. This study evaluated the similarity and seasonality of causative respiratory viruses for chronic obstructive pulmonary disease (COPD) and asthma exacerbations between retrospective multicenter cohort study and nationwide data.

METHODS

We compared data from the retrospective multicenter cohort study with Korean Influenza and Respiratory Surveillance System data between 2015 and 2018. Correlation, dynamic time warping (DTW), and seasonal autoregressive integrated moving average (SARIMA) analyses were performed.

RESULTS

Spearman correlation coefficients [ρ] indicated very strong (respiratory syncytial virus [RSV] [ρ = 0.8458] and influenza virus [IFV] [ρ = 0.8272]), strong (human metapneumovirus [HMPV] [ρ = 0.7177] and parainfluenza virus [PIV] [ρ = 0.6742]), and moderate (rhinovirus [RV] [ρ = 0.5850] and human coronavirus [HCoV] [ρ = 0.5158]) correlations. DTW analyses showed moderate (PIV) and high (IFV, RSV, and HMPV) synchronicity between the two datasets, while RV and HCoV showed low synchronicity. SARIMA analyses revealed 12-month seasonality for IFV, RSV, PIV, and HMPV. The peak season was winter for RSV and IFV, spring to summer for PIV, and spring for HMPV.

CONCLUSIONS

This was the first study to report the synchronicity between a retrospective multicenter cohort study of viruses that can cause COPD or asthma exacerbations and nationwide surveillance system data.

New methods to detect bacterial or viral infections in patients with chronic obstructive pulmonary disease

INTRODUCTION

Patients with chronic obstructive pulmonary disease (COPD) are frequently colonized and infected by respiratory pathogens. Identifying these infectious etiologies is critical for understanding the microbial dynamics of COPD and for the appropriate use of antimicrobials during exacerbations.

AREAS COVERED

Traditional methods, such as bacterial and viral cultures, have been standard in diagnosing respiratory infections. However, these methods have significant limitations, including lack of sensitivity and prolonged turnaround time. Modern molecular approaches offer rapid, sensitive, and specific detection, though they also come with their own challenges. This review explores and evaluates the clinical utility of the latest advancements in detecting bacterial and viral respiratory infections in COPD, encompassing molecular techniques, biomarkers, and emerging technologies.

EXPERT OPINION

In the evolving landscape of COPD management, integrating molecular diagnostics and emerging technologies holds great promise. The enhanced sensitivity of molecular techniques has significantly advanced our understanding of the role of microbes in COPD. However, many of these technologies have primarily been developed for pneumonia diagnosis or research applications, and their clinical utility in managing COPD requires further evaluation.

The roles of bacteria and viruses in COPD-Bronchiectasis association: A prospective cohort study

BACKGROUND

Exacerbations are implicated in bronchiectasis and COPD, which frequently co-exist [COPD-Bronchiectasis association (CBA)]. We aimed to determine the bacterial and viral spectrum at stable-state and exacerbation onset of CBA, and their association with exacerbations and clinical outcomes of CBA as compared with bronchiectasis.

METHODS

We prospectively collected spontaneous sputum from adults with CBA, bronchiectasis with (BO) and without airflow obstruction (BNO) for bacterial culture and viral detection at stable-state and exacerbations.

RESULTS

We enrolled 76 patients with CBA, 58 with BO, and 138 with BNO (711 stable and 207 exacerbation visits). Bacterial detection rate increased from BNO, CBA to BO at steady-state (P = 0.02), but not at AE onset (P = 0.91). No significant differences in viral detection rate were found among BNO, CBA and BO. Compared with steady-state, viral isolations occurred more frequently at exacerbation in BNO (15.8 % vs 32.1 %, P = 0.001) and CBA (19.5 % vs 30.6 %, P = 0.036) only. In CBA, isolation of viruses, human metapneumovirus and bacteria plus viruses was associated with exacerbation. Repeated detection of Pseudomonas aeruginosa (PA) correlated with higher modified Reiff score (P = 0.032) in CBA but not in BO (P = 0.178). Repeated detection of PA yielded a shorter time to the first exacerbation in CBA [median: 4.3 vs 11.1 months, P = 0.006] but not in BO (median: 8.4 vs 7.6 months, P = 0.47).

CONCLUSIONS

Isolation of any viruses, human metapneumovirus and bacterialplus viruses was associated with CBA exacerbations. Repeated detection of PA confers greater impact of future exacerbations on CBA than on BO.

Modelling the innate immune system in microphysiological systems

This critical review aims to highlight how modeling of the immune response has adapted over time to utilize microphysiological systems. Topics covered here will discuss the integral components of the immune system in various human body systems, and how these interactions are modeled using these systems. Through the use of microphysiological systems, we have not only expanded on foundations of basic immune cell information, but have also gleaned insight on how immune cells work both independently and collaboratively within an entire human body system.

Respiratory Infection Triggering Severe Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Background

Data are scarce on respiratory infections during severe acute exacerbation of chronic obstructive pulmonary disease (COPD). This study aimed to investigate respiratory infection patterns in the intensive care unit (ICU) and identify variables associated with infection type and patient outcome.

Methods

A retrospective, single-centre cohort study. All patients admitted (2015-2021) to our ICU for severe acute exacerbation of COPD were included. Logistic multivariable regression analysis was performed to predict factors associated with infection and assess the association between infection and outcome.

Results

We included 473 patients: 288 (60.9%) had respiratory infection and 139 (29.4%) required invasive mechanical ventilation. Eighty-nine (30.9%) had viral, 81 (28.1%) bacterial, 34 (11.8%) mixed, and 84 (29.2%) undocumented infections. Forty-seven (9.9%) patients died in the ICU and 67 (14.2%) in hospital. Factors associated with respiratory infection were temperature (odds ratio [+1°C]=1.43, P=0.008) and blood neutrophils (1.07, P=0.002). Male sex (2.21, P=0.02) and blood neutrophils were associated with bacterial infection (1.06, P=0.04). In a multivariable analysis, pneumonia (cause-specific hazard=1.75, P=0.005), respiratory rate (1.17, P=0.04), arterial partial pressure of carbon-dioxide (1.08, P=0.04), and lactate (1.14, P=0.02) were associated with the need for invasive MV. Age (1.03, P=0.03), immunodeficiency (1.96, P=0.02), and altered performance status (1.78, P=0.002) were associated with hospital mortality.

Conclusions

Respiratory infections, 39.9% of which were bacterial, were the main cause of severe acute exacerbation of COPD. Body temperature and blood neutrophils were single markers of infection. Pneumonia was associated with the need for invasive mechanical ventilation but not with hospital mortality, as opposed to age, immunodeficiency, and altered performance status.

Phenotypes, Etiotypes, and Endotypes of Exacerbations of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease is a major health problem with a high prevalence, a rising incidence, and substantial morbidity and mortality. Its course is punctuated by acute episodes of increased respiratory symptoms, termed exacerbations of chronic obstructive pulmonary disease (ECOPD). ECOPD are important events in the natural history of the disease, as they are associated with lung function decline and prolonged negative effects on quality of life. The present-day therapy for ECOPD with short courses of antibiotics and steroids and escalation of bronchodilators has resulted in only modest improvements in outcomes. Recent data indicate that ECOPD are heterogeneous, raising the need to identify distinct etioendophenotypes, incorporating traits of the acute event and of patients who experience recurrent events, to develop novel and targeted therapies. These characterizations can provide a complete clinical picture, the severity of which will dictate acute pharmacological treatment, and may also indicate whether a change in maintenance therapy is needed to reduce the risk of future exacerbations. In this review we discuss the latest knowledge of ECOPD types on the basis of clinical presentation, etiology, natural history, frequency, severity, and biomarkers in an attempt to characterize these events.

TLR7 promotes smoke-induced experimental lung damage through the activity of mast cell tryptase

Toll-like receptor 7 (TLR7) is known for eliciting immunity against single-stranded RNA viruses, and is increased in both human and cigarette smoke (CS)-induced, experimental chronic obstructive pulmonary disease (COPD). Here we show that the severity of CS-induced emphysema and COPD is reduced in TLR7-deficient mice, while inhalation of imiquimod, a TLR7-agonist, induces emphysema without CS exposure. This imiquimod-induced emphysema is reduced in mice deficient in mast cell protease-6, or when wild-type mice are treated with the mast cell stabilizer, cromolyn. Furthermore, therapeutic treatment with anti-TLR7 monoclonal antibody suppresses CS-induced emphysema, experimental COPD and accumulation of pulmonary mast cells in mice. Lastly, TLR7 mRNA is increased in pre-existing datasets from patients with COPD, while TLR7+ mast cells are increased in COPD lungs and associated with severity of COPD. Our results thus support roles for TLR7 in mediating emphysema and COPD through mast cell activity, and may implicate TLR7 as a potential therapeutic target.

The Lung Microbiome: A New Frontier for Lung and Brain Disease

Due to the limitations of culture techniques, the lung in a healthy state is traditionally considered to be a sterile organ. With the development of non-culture-dependent techniques, the presence of low-biomass microbiomes in the lungs has been identified. The species of the lung microbiome are similar to those of the oral microbiome, suggesting that the microbiome is derived passively within the lungs from the oral cavity via micro-aspiration. Elimination, immigration, and relative growth within its communities all contribute to the composition of the lung microbiome. The lung microbiome is reportedly altered in many lung diseases that have not traditionally been considered infectious or microbial, and potential pathways of microbe-host crosstalk are emerging. Recent studies have shown that the lung microbiome also plays an important role in brain autoimmunity. There is a close relationship between the lungs and the brain, which can be called the lung-brain axis. However, the problem now is that it is not well understood how the lung microbiota plays a role in the disease-specifically, whether there is a causal connection between disease and the lung microbiome. The lung microbiome includes bacteria, archaea, fungi, protozoa, and viruses. However, fungi and viruses have not been fully studied compared to bacteria in the lungs. In this review, we mainly discuss the role of the lung microbiome in chronic lung diseases and, in particular, we summarize the recent progress of the lung microbiome in multiple sclerosis, as well as the lung-brain axis.

Respiratory Viral and Bacterial Exacerbations of COPD—The Role of the Airway Epithelium

COPD is a leading cause of death worldwide, with acute exacerbations being a major contributor to disease morbidity and mortality. Indeed, exacerbations are associated with loss of lung function, and exacerbation frequency predicts poor prognosis. Respiratory infections are important triggers of acute exacerbations of COPD. This review examines the role of bacterial and viral infections, along with co-infections, in the pathogenesis of COPD exacerbations. Because the airway epithelium is the initial site of exposure both to cigarette smoke (or other pollutants) and to inhaled pathogens, we will focus on the role of airway epithelial cell responses in regulating the pathophysiology of exacerbations of COPD. This will include an examination of the interactions of cigarette smoke alone, and in combination with viral and bacterial exposures in modulating epithelial function and inflammatory and host defense pathways in the airways during COPD. Finally, we will briefly examine current and potential medication approaches to treat acute exacerbations of COPD triggered by respiratory infections.

Exploring the Change of Host and Microorganism in Chronic Obstructive Pulmonary Disease Patients Based on Metagenomic and Metatranscriptomic Sequencing

Background

Chronic obstructive pulmonary disease (COPD) is a universal respiratory disease resulting from the complex interactions between genes and environmental conditions. The process of COPD is deteriorated by repeated episodes of exacerbations, which are the primary reason for COPD-related morbidity and mortality. Bacterial pathogens are commonly identified in patients’ respiratory tracts both in the stable state and during acute exacerbations, with significant changes in the prevalence of airway bacteria occurring during acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Therefore, the changes in microbial composition and host inflammatory responses will be necessary to investigate the mechanistic link between the airway microbiome and chronic pulmonary inflammation in COPD patients.

Methods

We performed metatranscriptomic and metagenomic sequencing on sputum samples for twelve AECOPD patients before treatment and for four of them stable COPD (stabilization of AECOPD patients after treatment). Sequencing reads were classified by Kraken2, and the host gene expression was analyzed by Hisat2 and HTseq. The correlation between genes was obtained by the Spearman correlation coefficient. Mann–Whitney U-test was applied to identify microbes that exhibit significantly different distribution in two groups.

Results

At the phyla level, the top 5 dominant phyla were Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes, and Fusobacteria. The proportion of dominant gates in metagenomic data was similar in metatranscriptomic data. There were significant differences in the abundance of specific microorganisms at the class level between the two methods. No significant difference between AECOPD and stable COPD was found. However, the different expression levels of 5 host genes were significantly increased in stable COPD and were involved in immune response and inflammatory pathways, which were associated with macrophages.

Conclusion

Our study may provide a clue to investigate the mechanism of COPD and potential biomarkers in clinical diagnosis and treatment.

A Multicenter Study to Identify the Respiratory Pathogens Associated with Exacerbation of Chronic Obstructive Pulmonary Disease in Korea

BACKGROUND

Although respiratory tract infection is one of the most important factors triggering acute exacerbation of chronic obstructive pulmonary disease (AE-COPD), limited data are available to suggest an epidemiologic pattern of microbiology in South Korea.

METHODS

A multicenter observational study was conducted between January 2015 and December 2018 across 28 hospitals in South Korea. Adult patients with moderate-to-severe acute exacerbations of COPD were eligible to participate in the present study. The participants underwent all conventional tests to identify etiology of microbial pathogenesis. The primary outcome was the percentage of different microbiological pathogens causing AE-COPD. A comparative microbiological analysis of the patients with overlapping asthma-COPD (ACO) and pure COPD was performed.

RESULTS

We included 1,186 patients with AE-COPD. Patients with pure COPD constituted 87.9% and those with ACO accounted for 12.1%. Nearly half of the patients used an inhaled corticosteroid-containing regimen and one-fifth used systemic corticosteroids. Respiratory pathogens were found in 55.3% of all such patients. Bacteria and viruses were detected in 33% and 33.2%, respectively. Bacterial and viral coinfections were found in 10.9%. The most frequently detected bacteria were Pseudomonas aeruginosa (9.8%), and the most frequently detected virus was influenza A (10.4%). Multiple bacterial infections were more likely to appear in ACO than in pure COPD (8.3% vs. 3.6%, p=0.016).

CONCLUSION

Distinct microbiological patterns were identified in patients with moderate-to-severe AE-COPD in South Korea. These findings may improve evidence-based management of patients with AE-COPD and represent the basis for further studies investigating infectious pathogens in patients with COPD.

Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide and results in an economic and social burden that is both substantial and increasing. The natural history of COPD is punctuated by exacerbations, which have major short- and long-term implications on the patient and health care system. Evidence-based guidelines stipulate that early detection and prompt treatment of exacerbations are essential to ensure optimal outcomes and to reduce the burden of COPD. In this review, we provide a concise overview of COPD exacerbations and their risk factors and etiology (infection vs noninfectious), outlining the initial evaluation, triaging, and current management including invasive and noninvasive ventilation, in addition to the prognosis and the preventive strategies.

Host-Microbiome Interaction in Lung Cancer

Commensal microbiota has emerged as an essential biomarker and regulator of both tumorigenesis and response to cancer therapy. However, our current knowledge about microbiota in cancer has been largely limited to intestinal microbiota. As a mucosal organ harboring one of the largest surface areas in the body, the lung is exposed to a variety of microbes through inhalation and micro-aspiration, and is colonized by a diverse bacterial community in both physiological and pathological conditions. Importantly, increasing evidence has linked the lung microbiome to cancer development. Studies in lung cancer patients and mouse models have revealed tumor-associated dysregulation of the local microbiome in the lung, which in turn impacts cancer progression by shaping the tumor microenvironment and modulating the activity of tumor-infiltrating immune cells. These findings not only provide novel mechanistic insight into the biology of lung cancer but also shed light on new therapeutic targets and strategies for lung cancer prevention and treatment. The goal of this review is to discuss the key findings, remaining questions, and future directions in this new and exciting field.

Is the routine use of antipseudomonal antibiotics in acutely exacerbated COPD patients indicated: A retrospective analysis in 437 ICU patients

PURPOSE

Chronic obstructive pulmonary disease (COPD) is a risk factor for acquiring multiple drug resistant bacteria. The main objective of this analysis was to question a beneficial outcome in the routine use of antipseudomonal antibiotics in the empiric treatment of severe AECOPD in Intensive Care Unit patients.

MATERIAL AND METHODS

We report a retrospective, observational cohort study in adult patients with severe AECOPD admitted to ICU at a tertiary care university hospital. Antibiotic treatment on admission as well as microbiology samples were analyzed. The influence of SOFA score at admission, age, sex and antibiotic choice upon survival was investigated by multivariable analysis.

RESULTS

437 patients were included. Mean age was 68 years (±10), 46.5% were female. 271/437 patients (62%) were initially treated with antibiotics covering Pseudomonas aeruginosa. Overall, positive microbiology samples were found in 107 patients (24.5%). P. aeruginosa was only found in 3.7%. There was no significant difference in 30-day ICU mortality after adjusting for age, sex and severity of illness (20.4% ± 11.6 in patients with Pseudomonas inactive antibiotics versus 29.3% ± 10.8 in patients with PAA, p=0.113).

CONCLUSIONS

Empiric use of antipseudomonal antibiotics did not result in improved ICU survival in this retrospective analysis.

Use of Antibiotics in Chronic Obstructive Pulmonary Disease: What is Their Current Role in Older Patients?

Chronic obstructive pulmonary disease (COPD) has considerable morbidity and mortality in the older adult population. The role of antibiotics in the management of acute exacerbations of COPD (AECOPD) is currently evolving. Despite only mild benefits, most patients with AECOPD in ambulatory settings receive antibiotics based on clinical criteria. Utilization of point-of-care C-reactive protein (CRP) has reduced antibiotic prescriptions by 20% without compromising clinical outcomes. A strict protocol allowing antibiotic use only in patients with clinical criteria and CRP ≥ 20 mg/L has the potential to reduce antibiotic prescriptions for AECOPD in ambulatory settings by nearly 50%. Amoxicillin and doxycycline are commonly prescribed for AECOPD based on a favorable benefit-to-risk ratio. Prophylactic antibiotics have also been used in selected patients with severe COPD and frequent exacerbations. The use of continuous or intermittent azithromycin has demonstrated efficacy in reducing the frequency of AECOPD in this population; however, this approach has potential for the development of antibiotic resistance and adverse effects. The use of azithromycin prophylaxis in older patients with frequent AECOPD should be determined on a case-by-case basis after careful review, discussion, and counseling of the potential benefits and risks. The role of continuous doxycycline and pulsed moxifloxacin prophylaxis for frequent AECOPD remains controversial.

Prevention of Acute Exacerbation in Subjects with Moderate-to-very Severe COPD by Modulating Lower Respiratory Microbiome: Protocol of a Prospective, Multicenter, Randomized Controlled Trial

Background

COPD is a global respiratory disease that has produced a worldwide health care burden. Acute exacerbation of COPD (AECOPD) is the leading cause of death in patients with COPD and accounts for the majority of expenditure of COPD management. The colonization of potential pathogenic bacteria in the lower respiratory tract is an important cause of the acute exacerbation especially in patients with moderate and severe COPD. Some clinical studies have shown the potential of oral probiotics, aerosol-inhaled amikacin and combined vaccination to prevent AECOPD.

Methods and Analysis

We hypothesize that patients with stable COPD will benefit from aerosol-inhaled amikacin, oral probiotics or combined vaccination in terms of preventing acute exacerbation of COPD, slowing the progression of the disease and improving their quality of life. The trial aimsto investigate the efficacy and safety of the above interventions to decolonize bacteria in the lower respiratory tract and prevent acute exacerbation of COPD. In the study, 144 patients with stable phase of moderate-to-very severe COPD will be recruited and randomized into aerosol-inhaled amikacin group, oral probiotics group, combined vaccination group and the control group at a 1:1:1:1 ratio. The primary outcome is time to the first COPD exacerbation. Other endpoints include colonization of potential pathogenic bacteria in induced sputum, microbiome in induced sputum, pulmonary function and symptoms of patients, inflammation level and adverse events, serious adverse events, and death.

Role of pulmonary microorganisms in the development of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a chronic obstructive respiratory disease characterized by irreversible airway limitation and persistent respiratory symptoms. The main clinical symptoms of COPD are dyspnoea, chronic cough, and sputum. COPD is often accompanied by other respiratory diseases, which can cause worsening of the disease. COPD patients with dyspnoea and aggravation of cough and sputum symptoms represent acute exacerbations of COPD (AECOPD). There is mounting evidence suggesting that dysbiosis of pulmonary microbiota participates in the disease. However, investigations of dysbiosis of pulmonary microbiota and the disease are still in initial phases. To screen, diagnose, and treat this respiratory disease, integrating data from different studies can improve our understanding of the occurrence and development of COPD and AECOPD. In this review, COPD epidemiology and the primary triggering mechanism are explored. Emerging knowledge regarding the association of inflammation, caused by pulmonary microbiome imbalance, and changes in lung microbiome flora species involved in the development of the disease are also highlighted. These data will further our understanding of the pathogenesis of COPD and AECOPD and may yield novel strategies for the use of pulmonary microbiota as a potential therapeutic intervention.

Acute exacerbations of chronic obstructive pulmonary disease: in search of diagnostic biomarkers and treatable traits

Acute exacerbations of chronic obstructive pulmonary disease (COPD) are associated with a significant mortality, health and economic burden. Their diagnosis, assessment and management remain suboptimal and unchanged for decades. Recent clinical and translational studies revealed that the significant heterogeneity in mechanisms and outcomes of exacerbations could be resolved by grouping them etiologically. This is anticipated to lead to a better understanding of the biological processes that underlie each type of exacerbation and to allow the introduction of precision medicine interventions that could improve outcomes. This review summarises novel data on the diagnosis, phenotyping, targeted treatment and prevention of COPD exacerbations.

Bacterial infections in acute exacerbation of chronic obstructive pulmonary disease: a systematic review and meta-analysis

OBJECTIVE

Due to the importance of Chronic obstructive pulmonary disease (COPD) as the fourth cause of mortality worldwide and the lack of studies evaluating the prevalence of bacterial infections in disease exacerbation, this systematic review and meta-analysis was performed to determine the prevalence rate of bacterial infections in COPD patients.

METHODS

PubMed, ISI Web of Science, and Scopus databases were systematically searched for population-based prevalence studies (1980-2018). MeSH terms for "Bacterial infections" and "AECOPD" were used as search keywords. The selected studies were filtered according to the inclusion and exclusion criteria. Fixed and random-effects models were used for estimation of summary effect sizes. Between-study heterogeneity, as well as publication bias, were calculated.

RESULTS

Finally, 118 out of 31,440 studies were selected. The overall estimation of the prevalence of bacterial infection was 49.59% [95% confidence interval (CI) 0.4418-0.55]. The heterogeneity in estimating the pooled prevalence of bacterial infections was shown in the studies (Cochran Q test: 6615, P < 0.0001, I² = 98.23%). In addition, S. pneumoniae, H. influenzae, M. catarrhalis, A. baumannii, P. aeruginosa, and S. aureus were the most prevalent reported bacteria.

CONCLUSIONS

Our results as the first meta-analysis for the issue demonstrated that bacterial infections are an important risk factor for AECOPD. Further studies must be performed for understanding the exact role of bacterial agents in AECOPD and help physicians for more applicable preventive and therapeutic measurements.

Systemic inflammation and the effects of short-term antibiotic treatment for PPM positive patients with stable COPD

Objective

To evaluate patients with stable COPD for the presence of potentially pathogenic microorganisms (PPM), systemic inflammation and the effects of short-term antibiotic therapy in PPM positive patients.

Methods

From January 2016 to June 2017, we enrolled 96 stable COPD patients. Bacterial cultures from sputum collections were quantitated, along with markers for systemic inflammation including serum C-reactive protein (CRP), interleukin-8 (IL-8) and plasma fibrinogen (FIB) in all patients. All enrolled patients were followed for 12 months. Forty patients were identified as PPM positive and were randomly divided into an antibiotic group and a control group. The antibiotic group was treated with moxifloxacin orally for 6 days. Lung function and markers for systemic inflammation were repeatedly measured at 30 days and 6 months in PPM positive subjects.

Results

Binary logistic regression analysis showed that risk factors for PPM positive are bronchiectasis (OR 4.18, 95% CI 1.20-14.59; P=0.025), COPD assessment test (CAT) ≥20 (OR 17.55, 95% CI 2.82-109.18; P=0.002), spontaneous sputum (OR 15.09, 95% CI 1.36-168.02; P=0.027) and sputum purulence (OR 38.43, 95% CI 5.39-274.21; P=0.000). CRP and IL-8 were higher in PPM positive group than those in PPM negative group (P=0.001, P=0.007, respectively), but there were no differences of FIB between the two groups (P=0.086). Compared to the PPM negative group, the rate of acute exacerbation of COPD was higher (P=0.029) and time to next acute exacerbation was shorter (P=0.030) in PPM positive group. There were no differences in lung function and systemic inflammatory markers either in the control group or the antibiotic group at different time points of follow-up.

Conclusion

PPM exists in stable COPD patients and can cause systemic inflammation and is associated with acute exacerbation of COPD. Short-term antibiotic therapy had no effect on systemic inflammation nor on acute exacerbation of COPD.China Clinical Trials Registry: ChiCTR-IOR-15006769.

Smoking-induced iron dysregulation in the lung

Iron is one of the most abundant transition elements and is indispensable for almost all organisms. While the ability of iron to participate in redox chemistry is an essential requirement for participation in a range of vital enzymatic reactions, this same feature of iron also makes it dangerous in the generation of hydroxyl radicals and superoxide anions. Given the high local oxygen tensions in the lung, the regulation of iron acquisition, utilization, and storage therefore becomes vitally important, perhaps more so than in any other biological system. Iron plays a critical role in the biology of essentially every cell type in the lung, and in particular, changes in iron levels have important ramifications on immune function and the local lung microenvironment. There is substantial evidence that cigarette smoke causes iron dysregulation, with the implication that iron may be the link between smoking and smoking-related lung diseases. A better understanding of the connection between cigarette smoke, iron, and respiratory diseases will help to elucidate pathogenic mechanisms and aid in the identification of novel therapeutic targets.

Metabolomics and transcriptomics pathway approach reveals outcome-specific perturbations in COPD

Chronic obstructive pulmonary disease (COPD) comprises multiple phenotypes such as airflow obstruction, emphysema, and frequent episodes of acute worsening of respiratory symptoms, known as exacerbations. The goal of this pilot study was to test the usefulness of unbiased metabolomics and transcriptomics approaches to delineate biological pathways associated with COPD phenotypes and outcomes. Blood was collected from 149 current or former smokers with or without COPD and separated into peripheral blood mononuclear cells (PBMC) and plasma. PBMCs and plasma were analyzed using microarray and liquid chromatography mass spectrometry, respectively. Statistically significant transcripts and compounds were mapped to pathways using IMPaLA. Results showed that glycerophospholipid metabolism was associated with worse airflow obstruction and more COPD exacerbations. Sphingolipid metabolism was associated with worse lung function outcomes and exacerbation severity requiring hospitalizations. The strongest associations between a pathway and a certain COPD outcome were: fat digestion and absorption and T cell receptor signaling with lung function outcomes; antigen processing with exacerbation frequency; arginine and proline metabolism with exacerbation severity; and oxidative phosphorylation with emphysema. Overlaying transcriptomic and metabolomics datasets across pathways enabled outcome and phenotypic differences to be determined. Findings are relevant for identifying molecular targets for animal intervention studies and early intervention markers in human cohorts.

Bronchiectasis

Bronchiectasis is an important clinical syndrome because of its increasing prevalence, substantial economic burden on health care, and associated morbidity. Until recently, the disease was considered an orphan and essentially neglected from a therapeutic standpoint, but many recent advances have been made in the field. Several national registries have formed to provide databases from which to study patients with bronchiectasis. Experts published a consensus definition of a bronchiectasis-specific exacerbation that will serve as a unified definition for future clinical trials. Several inhaled antibiotic trials aimed at reducing exacerbation frequency have been completed. Researchers have investigated nonculture techniques, such as 16S ribosomal RNA (rRNA) and whole genome sequencing, to characterize the microbiological characteristics. Studies of anti-Pseudomonas antibodies are providing interesting insight into varying host responses to chronic Pseudomonas infection. After three successful trials demonstrating that macrolides reduce exacerbations in bronchiectasis, other antiinflammatory agents have been investigated, and a trial of a novel antiinflammatory drug is ongoing. A relatively robust study has been published in airway clearance, a therapy that is accepted universally as beneficial but that has never been accompanied by strong evidence. To build on the successes with bronchiectasis thus far, investigators must develop better definitions of phenotypes of bronchiectasis. In this regard, clinical tools have been developed to quantify disease severity and predict prognosis. Studies of different clinical phenotypes of bronchiectasis in patients with bronchiectasis have been published. With continued advances in the field of bronchiectasis, there is hope that evidenced-based therapies will become available.

Chronic obstructive pulmonary disease subpopulations and phenotyping

The diagnosis and treatment of chronic obstructive pulmonary disease (COPD) has been based largely on a one-size-fits-all approach. Diagnosis of COPD is based on meeting the physiologic criteria of fixed obstruction in forced expiratory flows and treatment focus on symptomatic relief, with limited effect on overall prognosis. However, patients with COPD have distinct features that determine very different evolutions of the disease. In this review we highlight distinct subgroups of COPD characterized by unique pathophysiologic derangements, response to treatment, and disease progression. It is likely that identification of subgroups of COPD will lead to discovery of much needed disease-modifying therapeutic approaches. We argue that a precision approach that integrates multiple dimensions (clinical, physiologic, imaging, and endotyping) is needed to move the field forward in the treatment of this disease.

Short-term particulate matter exposure influences nasal microbiota in a population of healthy subjects

BACKGROUND

Exposure to air pollutants, such as particulate matter (PM), represents a growing health problem. The aim of our study was to investigate whether PM could induce a dysbiosis in the nasal microbiota in terms of α-diversity and taxonomic composition.

METHODS

We investigated structure and characteristics of the microbiota of 40 healthy subjects through metabarcoding analysis of the V3-V4 regions of the 16s rRNA gene. Exposure to PM₁₀ and PM_2.5 was assessed with a personal sampler worn for 24h before sample collection (Day -1) and with measurements from monitoring stations (from Day -2 to Day -7).

RESULTS

We found an inverse association between PM₁₀ and PM_2.5 levels of the 3rd day preceding sampling (Day -3) and α-diversity indices (Chao1, Shannon and PD_whole_tree). Day -3 PM was inversely associated also with the majority of analyzed taxa, except for Moraxella, which showed a positive association. In addition, subjects showed different structural profiles identifying two groups: one characterized by an even community and another widely dominated by the Moraxella genus.

CONCLUSIONS

Our findings support the role of PM exposure in influencing microbiota and altering the normal homeostasis within the bacterial community. Whether these alterations could have a role in disease development and/or exacerbation needs further research.

Short term dynamics of the sputum microbiome among COPD patients

Chronic obstructive pulmonary disease (COPD) is an inflammatory disorder characterized by incompletely reversible airflow obstruction. The complexity of the lung microbial community in COPD patients has been highlighted in recent years. Evidence suggests that transplantation, medications, age, and disease severity influence microbial community membership. However, the dynamics of the lung microbiome in stable COPD patients remain poorly understood. In this study, we completed a longitudinal 16S ribosomal RNA survey of the lung microbiome on replicate sputum samples collected from 4 former smokers with COPD (Stage 2) within a 2-day time period. Samples from each individual over the two-day period were similar based on α-diversity, principle component analysis and taxonomy at the phyla and genera level. Sputum samples from COPD patients were also collected between 2–9 months of follow-up. Data suggest an increased variability of the sputum microbiota when comparing samples collected ≤ 3 months compared to those collected ≥ 4 months; however, no statistically significant shifts in the abundance (>2-fold) of taxa between the two time points was observed. Bacterial composition and the number of operational taxonomic units (OTUs) remained similar over time. Results from this study suggest that the sputum microbiome is relatively stable in clinically stable COPD patients (Stage 2). This study furthers our understanding of the dynamics of the lung microbiome in COPD patients.

Exacerbation of Bronchiectasis

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Antibiotics for treatment of acute exacerbation of chronic obstructive pulmonary disease: a network meta-analysis

Background

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is the most common reason for the hospitalization and death of pulmonary patients. The use of antibiotics as adjuvant therapy for AECOPD, however, is still a matter of debate.

Methods

In this study, we searched the PubMed, EmBase, and Cochrane databases for randomized controlled trials published until September 2016 that evaluated the use of antibiotics for AECOPD treatment. The major outcome variables were clinical cure rate and adverse effects. The microbiological response rate, relapse of exacerbation, and mortality were also analysed. A random-effect network was used to assess the effectiveness and tolerance of each antibiotic used for AECOPD treatment.

Results

In this meta-analysis, we included 19 articles that assessed 17 types of antibiotics used in 5906 AECOPD patients. The cluster ranking showed that dirithromycin had a high clinical cure rate with a low rate of adverse effects. Ofloxacin, ciprofloxacin, and trimethoprim-sulfamethoxazole had high clinical cure rates with median rates of adverse effects. In terms of the microbiological response rate, only doxycycline was significantly better than placebo (odds ratio (OR), 3.84; 95% confidence interval (CI), 1.96–7.54; p < 0.001). There were no other significant results with respect to the frequency of recurrence or mortality.

Conclusions

Our study indicated that dirithromycin is adequate for improving the clinical cure rate of patients with AECOPD with few adverse effects. Ofloxacin, ciprofloxacin, and trimethoprim-sulfamethoxazole are also recommended for disease treatment. However, caution should still be exercised when using antibiotics to treat AECOPD.

Trial Registration Not applicable.

Electronic supplementary material

The online version of this article (doi: 10.1186/s12890-017-0541-0) contains supplementary material, which is available to authorized users.

Reduced COPD Exacerbation Risk Correlates With Improved FEV1: A Meta-Regression Analysis

BACKGROUND

The mechanism by which various classes of medication reduce COPD exacerbation risk remains unknown. We hypothesized a correlation between reduced exacerbation risk and improvement in airway patency as measured according to FEV1.

METHODS

By systematic review, COPD trials were identified that reported therapeutic changes in predose FEV1 (dFEV1) and occurrence of moderate to severe exacerbations. Using meta-regression analysis, a model was generated with dFEV1 as the moderator variable and the absolute difference in exacerbation rate (RD), ratio of exacerbation rates (RRs), or hazard ratio (HR) as dependent variables.

RESULTS

The analysis of RD and RR included 119,227 patients, and the HR analysis included 73,475 patients. For every 100-mL change in predose FEV1, the HR decreased by 21% (95% CI, 17-26; P < .001; R2 = 0.85) and the absolute exacerbation rate decreased by 0.06 per patient per year (95% CI, 0.02-0.11; P = .009; R2 = 0.05), which corresponded to an RR of 0.86 (95% CI, 0.81-0.91; P < .001; R2 = 0.20). The relationship with exacerbation risk remained statistically significant across multiple subgroup analyses.

CONCLUSIONS

A significant correlation between increased FEV1 and lower COPD exacerbation risk suggests that airway patency is an important mechanism responsible for this effect.

Differences of lung microbiome in patients with clinically stable and exacerbated bronchiectasis

Background

Molecular-based diagnostic techniques can compensate for the inherent limitations of culture-based microbiology and provide a more comprehensive description of an entire community of bacteria at a particular anatomical site. Using culture-independent DNA-based molecular techniques, the aim of the present study was to characterize, differentiate, and compare the composition of lower airway bacterial microbiome between clinically stable and acutely infected patients with bronchiectasis experiencing exacerbation.

Methods

Patients with clinically stable bronchiectasis and those experiencing acutely exacerbated bronchiectasis were recruited. All patients underwent bronchoscopy. Paired sputum and bronchoalveolar lavage (BAL) samples were collected for microbiological tests. Molecular analysis was performed for BAL samples using 16S ribosomal RNA (rRNA) gene sequencing.

Results

The mean age of the 14 recruited patients was 60 years (range 42 to 78 years), and nine (64%) were female. Using quantitative culture and 16S rRNA sequencing, the common organisms identified from 14 BAL samples were Haemophilus influenzae, Pseudomonas aeruginosa and Moraxella catarrhalis, and Prevotella. Molecular techniques revealed Prevotella and Veillonella as potentially pathogenic anaerobic species. 16S rRNA gene sequencing yielded similar relative abundances and distributions of taxa in the stable and exacerbated bronchiectasis groups. Alpha diversity with richness, Simpson’s and Shannon indices, and beta diversity using principal coordinate analysis revealed no significant differences in lung microbiome between patients with clinically stable and exacerbated bronchiectasis.

Conclusion

Culture-based microbiological and molecular-based techniques did not reveal significant differences in the lung microbiome of patients who were clinically stable and those experiencing exacerbated bronchiectasis. Patient-specific microbial communities were dominated by one or several genera, regardless of clinical status. DNA sequencing could identify potentially pathogenic organisms unable to be identified using microbiological methods.

The Lung Microbiome, Immunity, and the Pathogenesis of Chronic Lung Disease

The development of culture-independent techniques for microbiological analysis has uncovered the previously unappreciated complexity of the bacterial microbiome at various anatomic sites. The microbiome of the lung has relatively less bacterial biomass when compared with the lower gastrointestinal tract yet displays considerable diversity. The composition of the lung microbiome is determined by elimination, immigration, and relative growth within its communities. Chronic lung disease alters these factors. Many forms of chronic lung disease demonstrate exacerbations that drive disease progression and are poorly understood. Mounting evidence supports ways in which microbiota dysbiosis can influence host defense and immunity, and in turn may contribute to disease exacerbations. Thus, the key to understanding the pathogenesis of chronic lung disease may reside in deciphering the complex interactions between the host, pathogen, and resident microbiota during stable disease and exacerbations. In this brief review we discuss new insights into these labyrinthine relationships.

Mathematical modeling of postcoinfection with influenza A virus and Streptococcus pneumoniae, with implications for pneumonia and COPD-risk assessment

Background

The interaction between influenza and pneumococcus is important for understanding how coinfection may exacerbate pneumonia. Secondary pneumococcal pneumonia associated with influenza infection is more likely to increase respiratory morbidity and mortality. This study aimed to assess exacerbated inflammatory effects posed by secondary pneumococcal pneumonia, given prior influenza infection.

Materials and methods

A well-derived mathematical within-host dynamic model of coinfection with influenza A virus and Streptococcus pneumoniae (SP) integrated with dose–response relationships composed of previously published mouse experimental data and clinical studies was implemented to study potentially exacerbated inflammatory responses in pneumonia based on a probabilistic approach.

Results

We found that TNFα is likely to be the most sensitive biomarker reflecting inflammatory response during coinfection among three explored cytokines. We showed that the worst inflammatory effects would occur at day 7 SP coinfection, with risk probability of 50% (likely) to develop severe inflammatory responses. Our model also showed that the day of secondary SP infection had much more impact on the severity of inflammatory responses in pneumonia compared to the effects caused by initial virus titers and bacteria loads.

Conclusion

People and health care workers should be wary of secondary SP infection on day 7 post-influenza infection for prompt and proper control-measure implementation. Our quantitative risk-assessment framework can provide new insights into improvements in respiratory health especially, predominantly due to chronic obstructive pulmonary disease (COPD).

Serum inflammatory biomarkers and clinical outcomes of COPD exacerbation caused by different pathogens

BACKGROUND AND OBJECTIVE

COPD exacerbation is characterized by worsening of symptoms, warranting change in treatment. Systemic and airway inflammation play roles in the pathogenesis of COPD exacerbation. We hypothesized whether increased serum inflammatory biomarkers are associated with the clinical outcomes of COPD exacerbation caused by different infectious pathogens.

METHODS

COPD patients with exacerbation were recruited from a hospital emergency department during 2014-2015. Serum procalcitonin (PCT) and C-reactive protein (CRP) were measured. Dyspnea, eosinopenia, consolidation, acidemia, and atrial fibrillation (DECAF) score was calculated for predicting mortality. Multiplex polymerase chain reaction was carried out for respiratory viral assay from nasopharyngeal swabs, and sputum bacterial culture was also performed. Hospital mortality, invasive mechanical ventilation requirement, and length of hospital stay (LOS) were evaluated, and their associations with clinical characteristics, DECAF score, and serum biomarkers were examined.

RESULTS

A total of 62 COPD patients were enrolled. These patients were classified as Global Initiative for Obstructive Lung Disease (GOLD) stage 2, 3, and 4 in 12.9%, 6.4%, and 80.7% of cases, respectively. Isolated bacterial exacerbation was recovered in 30.6% of exacerbation episodes: Klebsiella pneumoniae was the most commonly identified bacteria. Viral pathogens and coinfections were noted in 9.6% and 16.1% of exacerbated patients, respectively. Influenza was the most commonly detected viral pathogen. Serum biomarkers and DECAF score for viruses, bacteria, coinfection, and noninfectious causes of exacerbations were similar. Neither DECAF score nor serum biomarkers were able to differentiate patients with and without mortality or requiring mechanical ventilation. Increased serum PCT was noted in patients with LOS ≥7 days when compared with those with LOS <7 days (0.38 ng/mL vs 0.1 ng/mL; P=0.035).

CONCLUSION

Increased serum PCT is associated with longer LOS in COPD exacerbation. However, CRP and DECAF score play limited roles in predicting clinical outcome and lack an association with causes of exacerbation.

Nontypeable Haemophilus influenzae and chronic obstructive pulmonary disease: a review for clinicians

Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of morbidity and mortality worldwide. In the lower airways of COPD patients, bacterial infection is a common phenomenon and Haemophilus influenzae is the most commonly identified bacteria. Haemophilus influenzae is divided into typeable and nontypeable (NTHi) strains based on the presence or absence of a polysaccharide capsule. While NTHi is a common commensal in the human nasopharynx, it is associated with considerable inflammation when it is present in the lower airways of COPD patients, resulting in morbidity due to worsening symptoms and increased frequency of COPD exacerbations. Treatment of lower airway NTHi infection with antibiotics, though successful in the short term, does not offer long-term protection against reinfection, nor does it change the course of the disease. Hence, there has been much interest in the development of an effective NTHi vaccine. This review will summarize the current literature concerning the role of NTHi infections in COPD patients and the consequences of using prophylactic antibiotics in patients with COPD. There is particular focus on the rationale, findings of clinical studies and possible future directions of NTHi vaccines in patients with COPD.

A prospective, observational cohort study of the seasonal dynamics of airway pathogens in the aetiology of exacerbations in COPD

BACKGROUND

The aetiology of acute exacerbations of COPD (AECOPD) is incompletely understood. Understanding the relationship between chronic bacterial airway infection and viral exposure may explain the incidence and seasonality of these events.

METHODS

In this prospective, observational cohort study (NCT01360398), patients with COPD aged 40-85 years underwent sputum sampling monthly and at exacerbation for detection of bacteria and viruses. Results are presented for subjects in the full cohort, followed for 1 year. Interactions between exacerbation occurrence and pathogens were investigated by generalised estimating equation and stratified conditional logistic regression analyses.

FINDINGS

The mean exacerbation rate per patient-year was 3.04 (95% CI 2.63 to 3.50). At AECOPD, the most common bacterial species were non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis, and the most common virus was rhinovirus. Logistic regression analyses (culture bacterial detection) showed significant OR for AECOPD occurrence when M. catarrhalis was detected regardless of season (5.09 (95% CI 2.76 to 9.41)). When NTHi was detected, the increased risk of exacerbation was greater in high season (October-March, OR 3.04 (1.80 to 5.13)) than low season (OR 1.22 (0.68 to 2.22)). Bacterial and viral coinfection was more frequent at exacerbation (24.9%) than stable state (8.6%). A significant interaction was detected between NTHi and rhinovirus presence and AECOPD risk (OR 5.18 (1.92 to 13.99); p=0.031).

CONCLUSIONS

AECOPD aetiology varies with season. Rises in incidence in winter may be driven by increased pathogen presence as well as an interaction between NTHi airway infection and effects of viral infection.

TRIAL REGISTRATION NUMBER

Results, NCT01360398.

Bronchial microbiome, PA biofilm-forming capacity and exacerbation in severe COPD patients colonized by P. aeruginosa

AIM

The bronchial microbiome of severe chronic obstructive pulmonary disease patients colonized by Pseudomonas aeruginosa was analyzed using 16S rRNA gene sequencing to identify differences related to biofilm-forming capacity.

PATIENTS & METHODS

Patient sputum samples from 21 patients were studied.

RESULTS

Statistically significant differences related to biofilm-forming capacity were only found for genera with relative abundances <1%, and Fusobacterium was over-represented when biofilm-forming capacity was high. Genera with relative abundances >50% which increased from baseline were observed in 10/14 exacerbations, but corresponded to Pseudomonas only in three episodes, while other pathogenic genera were identified in seven.

CONCLUSION

The bronchial microbiome shows differences according with P. aeruginosa biofilm-forming capacity. Pathogenic microorganisms other than P. aeruginosa cause a significant part of the exacerbations in colonized chronic obstructive pulmonary disease patients.

Bacterial Lysis through Interference with Peptidoglycan Synthesis Increases Biofilm Formation by Nontypeable Haemophilus influenzae

Most, if not all, bacteria form a biofilm, a multicellular structure that protects them from antimicrobial actions of the host immune system and affords resistance to antibiotics. The latter is especially disturbing with the increase in multiresistant bacterial clones worldwide. Bacterial biofilm formation is a multistep process that starts with surface adhesion, after which attached bacteria divide and give rise to biomass. The actual steps required for Haemophilus influenzae biofilm formation are largely not known. We show that interference with peptidoglycan biosynthesis increases biofilm formation because of the release of bacterial genomic DNA. Subinhibitory concentrations of β-lactam antibiotics, which are often prescribed to treat H. influenzae infections, increase biofilm formation through a similar mechanism. Therefore, when β-lactam antibiotics do not reach their MIC in vivo, they might not only drive selection for β-lactam-resistant clones but also increase biofilm formation and resistance to other antimicrobial compounds.

Nontypeable Haemophilus influenzae (NTHi) is an opportunistic pathogen that mainly causes otitis media in children and community-acquired pneumonia or exacerbations of chronic obstructive pulmonary disease in adults. A large variety of studies suggest that biofilm formation by NTHi may be an important step in the pathogenesis of this bacterium. However, the underlying mechanisms involved in this process are poorly elucidated. In this study, we used a transposon mutant library to identify bacterial genes involved in biofilm formation. The growth and biofilm formation of 4,172 transposon mutants were determined, and the involvement of the identified genes in biofilm formation was validated in in vitro experiments. Here, we present experimental data showing that increased bacterial lysis, through interference with peptidoglycan synthesis, results in elevated levels of extracellular DNA, which increased biofilm formation. Interestingly, similar results were obtained with subinhibitory concentrations of β-lactam antibiotics, known to interfere with peptidoglycan synthesis, but such an effect does not appear with other classes of antibiotics. These results indicate that treatment with β-lactam antibiotics, especially for β-lactam-resistant NTHi isolates, might increase resistance to antibiotics by increasing biofilm formation.

IMPORTANCE Most, if not all, bacteria form a biofilm, a multicellular structure that protects them from antimicrobial actions of the host immune system and affords resistance to antibiotics. The latter is especially disturbing with the increase in multiresistant bacterial clones worldwide. Bacterial biofilm formation is a multistep process that starts with surface adhesion, after which attached bacteria divide and give rise to biomass. The actual steps required for Haemophilus influenzae biofilm formation are largely not known. We show that interference with peptidoglycan biosynthesis increases biofilm formation because of the release of bacterial genomic DNA. Subinhibitory concentrations of β-lactam antibiotics, which are often prescribed to treat H. influenzae infections, increase biofilm formation through a similar mechanism. Therefore, when β-lactam antibiotics do not reach their MIC in vivo, they might not only drive selection for β-lactam-resistant clones but also increase biofilm formation and resistance to other antimicrobial compounds.

Nano-based rescue of dysfunctional autophagy in chronic obstructive lung diseases

INTRODUCTION

ΔF508-CFTR (cystic fibrosis transmembrane conductance regulator) is a common CF-mutation that is known to induce oxidative-inflammatory stress through activation of reactive oxygen species (ROS), which induces autophagy-impairment resulting in accumulation of CFTR in aggresome-bodies. Cysteamine, the reduced form of cystamine, is a FDA-approved drug that has anti-oxidant, anti-bacterial, and mucolytic properties. This drug has been shown in a recent clinical trial to decrease lung inflammation and improve lung function in CF patients by potentially restoring autophagy and allowing CFTR to be trafficked to the cell membrane. Areas covered: The delivery of cysteamine to airway epithelia of chronic subjects prerequisite the need for a delivery system to allow rescue of dysfunctional autophagy. Expert opinion: We anticipate based on our ongoing studies that PLGA-PEG- or Dendrimer-mediated cysteamine delivery could allow sustained airway delivery over standard cysteamine tablets or delay release capsules that are currently used for systemic treatment. In addition, proposed nano-based autophagy induction strategy can also allow rescue of cigarette smoke (CS) induced acquired-CFTR dysfunction seen in chronic obstructive pulmonary disease (COPD)-emphysema subjects. The CS induced acquired-CFTR dysfunction involves CFTR-accumulation in aggresome-bodies that can be rescued by an autophagy-inducing antioxidant drug, cysteamine. Moreover, chronic CS-exposure generates ROS that induces overall protein-misfolding and aggregation of ubiquitinated-proteins as aggresome-bodies via autophagy-impairment that can be also be resolved by treatment with autophagy-inducing antioxidant drug, cysteamine.

A pathogenic role for tumor necrosis factor-related apoptosis-inducing ligand in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a life-threatening inflammatory respiratory disorder, often induced by cigarette smoke (CS) exposure. The development of effective therapies is impaired by a lack of understanding of the underlining mechanisms. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a cytokine with inflammatory and apoptotic properties. We interrogated a mouse model of CS-induced experimental COPD and human tissues to identify a novel role for TRAIL in COPD pathogenesis. CS exposure of wild-type mice increased TRAIL and its receptor messenger RNA (mRNA) expression and protein levels, as well as the number of TRAIL(+)CD11b(+) monocytes in the lung. TRAIL and its receptor mRNA were also increased in human COPD. CS-exposed TRAIL-deficient mice had decreased pulmonary inflammation, pro-inflammatory mediators, emphysema-like alveolar enlargement, and improved lung function. TRAIL-deficient mice also developed spontaneous small airway changes with increased epithelial cell thickness and collagen deposition, independent of CS exposure. Importantly, therapeutic neutralization of TRAIL, after the establishment of early-stage experimental COPD, reduced pulmonary inflammation, emphysema-like alveolar enlargement, and small airway changes. These data provide further evidence for TRAIL being a pivotal inflammatory factor in respiratory diseases, and the first preclinical evidence to suggest that therapeutic agents that target TRAIL may be effective in COPD therapy.

Inhaled corticosteroids and the increased risk of pneumonia: what's new? A 2015 updated review

There is a considerable amount of evidence that supports the possibility of an increased risk of pneumonia associated with prolonged use of inhaled corticosteroids (ICS) in patients with chronic obstructive pulmonary disease (COPD). However, as yet, no statistically significant increase in pneumonia-related 30-day mortality in patients on ICS has been demonstrated. The lack of objective pneumonia definitions and radiological confirmations have been a major source of bias, because of the similarities in clinical presentation between pneumonia and acute exacerbations of COPD. One of the newer fluticasone furoate studies overcomes these limitations and also provides an assessment of a range of doses, suggesting that the therapeutic window is quite narrow and that conventional dosing has probably been too high, although the absolute risk may be different compared to other drugs. Newer studies were not able to rule out budesonide as responsible for pneumonia, as previous evidence suggested, and there is still need for evidence from head-to-head comparisons in order to better assess possible intra-class differences. Although the exact mechanisms by which ICS increase the risk of pneumonia are not fully understood, the immunosuppressive effects of ICS on the respiratory epithelium and the disruption of the lung microbiome are most likely to be implicated. Given that COPD represents such a complex and heterogeneous disease, attempts are being made to identify clinical phenotypes with clear therapeutic implications, in order to optimize the pharmacological treatment of COPD and avoid the indiscriminate use of ICS. If deemed necessary, gradual withdrawal of ICS appears to be well tolerated. Vaccination against pneumococcus and influenza should be emphasized in patients with COPD receiving ICS. Physicians should keep in mind that signs and symptoms of pneumonia in COPD patients may be initially indistinguishable from those of an exacerbation, and that patients with COPD appear to be at increased risk of developing pneumonia as a complication of ICS therapy.

COPD Exacerbations Are Associated With Proinflammatory Degradation of Hyaluronic Acid

BACKGROUND

COPD is characterized by chronic airway inflammation and remodeling, with serious modifications of the extracellular matrix (ECM). Hyaluronic acid (HA) is an abundant ECM molecule in the lung with various biologic functions that depend on its molecular weight (MW). High-MW HA exhibits antiinflammatory and immunosuppressive effects, whereas low-MW HA is proinflammatory. In this study, we investigated whether acute exacerbations of COPD (AECOPDs), which affect patient quality of life and survival, are associated with altered HA turnover in BAL.

METHODS

We used BAL from patients with stable COPD (n = 53) or during AECOPD (n = 44) matched for demographics and clinical characteristics and BAL from control subjects (n = 15). HA, HA synthase-1 (HAS-1), and hyaluronidase (HYAL) values were determined by enzyme-linked immunosorbent assay, and HYAL activity was determined by HA zymography. The MW of HA was analyzed by agarose electrophoresis.

RESULTS

Levels of HA, HAS-1, and HYAL were significantly increased in BAL of patients with stable COPD and during exacerbations compared with control subjects. HYAL activity was significantly increased in BAL of patients with AECOPD, resulting in an increase of low-MW HA during exacerbations. In patients with AECOPD, we also observed a significant negative correlation of HA and HYAL levels with FEV1 % predicted but not with diffusing capacity of lung for carbon monoxide % predicted, indicating that increased HA degradation may be more associated with airway obstruction than with emphysema.

CONCLUSIONS

AECOPDs are associated with increased HYAL activity in BAL and subsequent degradation of HA, which may contribute to airway inflammation and subsequent lung function decline during exacerbations.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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