The role of acute and chronic respiratory colonization and infections in the pathogenesis of COPD

Moraxella catarrhalis bacteremic pneumonia

An 81-year-old man with lung cancer with bone metastases, interstitial pneumonia, and emphysema, was hospitalized for pain control. He developed fever and chills during hospitalization. Physical examination revealed a fever of 39.1 °C, but there were no findings on history or physical examination to suggest the source of the infection. Gram-negative cocci were detected in the blood culture (Fig. 1) and in a Gram stained sputum smear (Figs. 3 and 4). Neisseria meningitis and Neisseria gonorrhoeae were ruled out based on history and an absence of suggestive symptoms. The cause of his fever was diagnosed as Moraxella catarrhalis bacteremic pneumonia based on the blood culture and the sputum smear results, and he was treated with intravenous ceftriaxone. This case illustrates the importance of Gram staining of sputum and blood culture. Moraxella catarrhalis should be considered in the differential diagnosis when gram-negative cocci are detected in the blood and the sputum.

Airway microbiome composition correlates with lung function and arterial stiffness in an age-dependent manner

Objective

To investigate age-associated changes in airway microbiome composition and their relationships with lung function and arterial stiffness among genetically matched young and elderly pairs.

Methods

Twenty-four genetically linked family pairs comprised of younger (≤40 years) and older (≥60 years) healthy participants were recruited (Total n = 48). Lung function and arterial stiffness (carotid-femoral pulse wave velocity (PWV) and augmentation index (AIx)) were assessed. Sputum samples were collected for targeted 16S rRNA gene amplicon sequencing and correlations between microbiome composition, lung function and arterial stiffness were investigated.

Results

Elderly participants exhibited reductions in lung function (FEV1 (p<0.001), FVC (p<0.001) and percentage FEV1/FVC (p = 0.003)) and a 1.3–3.9-fold increase in arterial stiffness (p<0.001) relative to genetically related younger adults. Elderly adults had a higher relative abundance of Firmicutes (p = 0.035) and lower relative abundance of Proteobacteria (p = 0.014), including specific genera Haemophilus (p = 0.024) and Lautropia (p = 0.020) which were enriched in the younger adults. Alpha diversity was comparable between young and elderly pairs (p>0.05) but was inversely associated with lung function (FEV1%Predicted and FVC %Predicted) in the young (p = 0.006 and p = 0.003) though not the elderly (p = 0.481 and p = 0.696). Conversely, alpha diversity was negatively associated with PWV in the elderly (p = 0.01) but not the young (p = 0.569). Specifically, phylum Firmicutes including the genus Gemella were correlated with lung function (FVC %Predicted) in the young group (p = 0.047 and p = 0.040), while Fusobacteria and Leptotrichia were associated with arterial stiffness (PWV) in the elderly (both p = 0.004).

Conclusion

Ageing is associated with increased Firmicutes and decreased Proteobacteria representation in the airway microbiome among a healthy Asian cohort. The diversity and composition of the airway microbiome is independently associated with lung function and arterial stiffness in the young and elderly groups respectively. This suggests differential microbial associations with these phenotypes at specific stages of life with potential prognostic implications.

Risk of exacerbation of pulmonary comorbidities in patients with rheumatoid arthritis after initiation of abatacept versus TNF inhibitors: A cohort study

BACKGROUND

Biologic agents may pose a potential risk for exacerbations of pulmonary comorbidities in rheumatoid arthritis (RA) patients.

METHODS

Using U.S. Medicare and Truven MarketScan databases, we identified three cohorts of RA patients with interstitial lung disease (ILD), chronic obstructive pulmonary disease (COPD), or asthma who initiated abatacept or a TNF inhibitor (TNFi). The primary outcome was a composite exacerbation of individual pulmonary comorbidities based on inpatient or emergency department (ED) visits due to exacerbation of the given pulmonary comorbidity. To adjust for >60 baseline confounders, we used propensity-score fine stratification (PSS) and weighting. Negative binomial regression model estimated a cohort-specific incidence rate ratio (IRR) and 95% confidence interval (CI) of the primary outcome per database, comparing abatacept versus TNFi. Database-specific IRRs were combined using a random-effects meta-analysis.

RESULTS

We identified 3,295 ILD, 7,161 COPD, and 5,613 asthma patients with RA who initiated either abatacept or a TNFi. IR of composite exacerbation was high in all three pulmonary cohorts but highest in COPD cohort (3.59-11.80 per 100 person-years in ILD, 20.68-34.97 in COPD, and 4.66-13.78 in asthma). After PSS weighting, the combined IRR (95%CI) in abatacept initiators versus TNFi initiators was 0.44 (0.18-1.09) for ILD exacerbation, 0.91 (0.80-1.03) for COPD exacerbation, and 0.81 (0.54-1.22) for asthma exacerbation.

CONCLUSION

Among patients with RA and pulmonary comorbidities, exacerbations requiring inpatient or ED visits occurred frequently after initiating abatacept or TNFi. Overall, we found no significant difference in the risk of ILD, COPD or asthma exacerbation between abatacept and TNFi initiators, but precision of our estimates is limited.

Colonization by Pneumocystis jirovecii in patients with chronic obstructive pulmonary disease: association with exacerbations and lung function status

Exposure to Pneumocystis jirovecii (P. jirovecii) can lead to a wide variety of presenting features ranging from colonization in immunocompetent patients with lung disease, to invasive infections in immunocompromised hosts. Colonization by this fungus in patients with chronic obstructive pulmonary disease (COPD) could be associated with higher rates of exacerbations and impaired lung function in these patients.

Our objective was to determine whether colonization by P. jirovecii in patients with COPD is associated with increased exacerbations and deterioration of lung function.

This was a prospective cohort study on patients with COPD. All participants meeting selection criteria underwent clinical and microbiological assessments and were then classified as colonized vs. non-colonized patients. Chi-squared tests were performed and multivariate logistic models were fitted in order to obtain risk ratios (RR) with 95% confidence intervals (CI).

We documented a frequency of colonization by P. jirovecii of 32.3%. Most patients were categorized as having GOLD B and D COPD. The history of significant exacerbations in the last year, health status impairment (COPD Assesment Tool ≥10), airflow limitation (percent of post-bronchodilator FEV1), and BODEx score (≥5) were similar between groups. After a 52-week follow-up period, the rate of adjusted significant exacerbations did not differ between groups. However, a decrease in FEVI was found in both groups.

Sputum Microbiome Dynamics in Chronic Obstructive Pulmonary Disease Patients during an Exacerbation Event and Post-Stabilization

BACKGROUND

Chronic obstructive pulmonary disease (COPD) affects up to 65 million people worldwide, and COPD exacerbation causes tissue damage and subsequent loss of lung function. It is a multifactorial event in which respiratory infections are involved, but little is known about its dynamics.

OBJECTIVES

The objective of our study was to determine the microbiome composition during an exacerbation event and post-stabilization.

METHODS

We conducted an observational analytical study of a cohort of 55 COPD patients in which 2 sputum samples (the first taken during an exacerbation event and the second during clinical post-stabilization) were submitted to 16s RNA ribosomal analysis by Illumina Miseq Next Generation Sequencing (NGS). The presence of respiratory viruses was also determined.

RESULTS

Our study found a stable microbiome composition in the post-stabilization sputum samples of COPD patients, and 4 additional microbiomes in samples taken during the exacerbation, 3 of which showed a marked dysbiosis by Haemophilus, Pseudomonas, and Serratia. The fourth exacerbation microbiome had a very similar composition to post-stabilization samples, but some pathogens such as Moraxella and respiratory viruses were also found.

CONCLUSIONS

Our study reveals the main protagonists involved in lung microbiome dynamics during an exacerbation event and post-stabilization in COPD patients by NGS analysis.

Microbiome-focused asthma management strategies

Asthma is a common, heterogeneous and serious disease with high prevalence globally. Poorly controlled, steroid-resistant asthma is particularly important as there are no effective therapies and it exerts substantial healthcare and societal burden. The role of microbiomes, particularly in chronic diseases has generated considerable interest in recent times. Existing evidence clearly demonstrates an association between asthma initiation and the microbiome, both respiratory and gastro-intestinal, although its' roles are poorly understood when assessing the asthma progression or heterogeneity (i.e. phenotypes/endotypes) across different geographical locations. Moreover, modulating microbiomes could be preventive and/or therapeutic in patients with asthma warrants urgent attention. Here, we review recent advances in assessing the role of microbiomes in asthma and present the challenges associated with the potential therapeutic utility of modifying microbiomes in management.

New therapeutic targets for the prevention of infectious acute exacerbations of COPD: role of epithelial adhesion molecules and inflammatory pathways

Chronic respiratory diseases are among the leading causes of mortality worldwide, with the major contributor, chronic obstructive pulmonary disease (COPD) accounting for approximately 3 million deaths annually. Frequent acute exacerbations (AEs) of COPD (AECOPD) drive clinical and functional decline in COPD and are associated with accelerated loss of lung function, increased mortality, decreased health-related quality of life and significant economic costs. Infections with a small subgroup of pathogens precipitate the majority of AEs and consequently constitute a significant comorbidity in COPD. However, current pharmacological interventions are ineffective in preventing infectious exacerbations and their treatment is compromised by the rapid development of antibiotic resistance. Thus, alternative preventative therapies need to be considered. Pathogen adherence to the pulmonary epithelium through host receptors is the prerequisite step for invasion and subsequent infection of surrounding structures. Thus, disruption of bacterial-host cell interactions with receptor antagonists or modulation of the ensuing inflammatory profile present attractive avenues for therapeutic development. This review explores key mediators of pathogen-host interactions that may offer new therapeutic targets with the potential to prevent viral/bacterial-mediated AECOPD. There are several conceptual and methodological hurdles hampering the development of new therapies that require further research and resolution.

Deficient pulmonary IFN-β expression in COPD patients

COPD patients are prone to acute infectious exacerbations that impair their quality of life and hamper prognosis. The purpose of the present study was to investigate the in situ IFN-β response in the lungs of stable COPD and non-COPD patients. Lung samples from 70 subjects (9 control never smokers, 19 control smokers without COPD, 21 patients with moderate COPD and 21 patients with very severe COPD) were studied for the expression of IFN-β, its main transcription factor, IRF-7, and two products of its autocrine function, namely RIG-I and MDA-5, by immunohistochemical techniques and quantitative real-time PCR. IFN-β, IRF-7, RIG-I and MDA-5 were widely detected in most lung cell types. In epithelial tissues and alveolar macrophages, IFN-β and IRF-7 labeling scores were decreased up to 65% and 74%, respectively, for COPD patients, paralleling an analogous reduction (43% and 65%, respectively) in the amount of their lung mRNA. Moreover, this decreased production of IFN-β in COPD patients correlated with a similar decrease in the expression of RIG-I and MDA-5, two essential members of the innate immune system. Our study indicates that most lung cells from stable COPD patients show a constitutive decreased expression of IFN-β, IRF-7, RIG-I and MDA-5, suggesting that this deficiency is the main cause of their acute viral exacerbations.

Mucociliary Clearance in Former Tobacco Smokers with Both Chronic Obstructive Pulmonary Disease and Chronic Bronchitis and the Effect of Roflumilast

Background: Little is known of the repeatability and reliability of mucociliary clearance (MCC) in former tobacco smokers who have both chronic obstructive pulmonary disease (COPD) and chronic bronchitis (CB). Less is known of the effect of roflumilast, a selective inhibitor of PDE4, on MCC in these patients. Methods: Former tobacco smokers with COPD and CB were treated for 4 weeks with either roflumilast, or placebo, in a randomized, crossover trial. The following were measured on two baseline and two posttreatment visits: MCC values through 90 minutes, following inhalation of ^99mtechnetium sulfur colloid and gamma camera imaging; outer:inner (O:I) deposition ratio; forced expiratory volume in 1 second (FEV₁); and symptom scores. Comparisons included: MCC measures through 30 minutes (MCC30), 60 minutes (MCC60), and 90 minutes (MCC90) on the two baseline visits (n = 9) and mean change [(roflumilast - baseline)-(placebo - baseline)] for MCC30, MCC60, MCC90, and FEV₁ (n = 8). Associations between MCC measurements, FEV₁ and O:I ratio with symptom scores were also examined. Results: Pearson correlation tests indicated good repeatability for baseline measures of MCC30, MCC60, and MCC90 and intraclass correlation coefficients indicated good reliability. Only FEV₁ (percent predicted) improved significantly following roflumilast treatment. There were no statistically significant correlations between MCC measures and symptom scores. Lower FEV₁ values were significantly associated with increased shortness of breath (dyspnea), and lower O:I ratios (more inner region deposition) were significantly associated with increased cough and sputum. Conclusions: Measurements of MCC30, MCC60, and MCC90 are repeatable and reliable in former tobacco smokers with both COPD and CB. One month of treatment with roflumilast did not improve MCC in this limited study. Airway narrowing in the larger, central airways of these subjects could lead to decreased FEV₁, increased inner region deposition of the radiolabeled particles, and the associated increase in symptoms of dyspnea, cough, and sputum.

Autophagy augmentation alleviates cigarette smoke-induced CFTR-dysfunction, ceramide-accumulation and COPD-emphysema pathogenesis

In this study, we aimed to investigate precise mechanism(s) of sphingolipid-imbalance and resulting ceramide-accumulation in COPD-emphysema. Where, human and murine emphysema lung tissues or human bronchial epithelial cells (Beas2b) were used for experimental analysis. We found that lungs of smokers and COPD-subjects with increasing emphysema severity demonstrate sphingolipid-imbalance, resulting in significant ceramide-accumulation and increased ceramide/sphingosine ratio, as compared to non-emphysema/non-smoker controls. Next, we found a substantial increase in emphysema chronicity-related ceramide-accumulation in murine (C57BL/6) lungs, while sphingosine levels only slightly increased. In accordance, the expression of the acid ceramidase decreased after CS-exposure. Moreover, CS-induced (sub-chronic) ceramide-accumulation was significantly (p < 0.05) reduced by treatment with TFEB/autophagy-inducing drug, gemfibrozil (GEM), suggesting that autophagy regulates CS-induced ceramide-accumulation. Next, we validated experimentally that autophagy/lipophagy-induction using an anti-oxidant, cysteamine, significantly (p < 0.05) reduces CS-extract (CSE)-mediated intracellular-ceramide-accumulation in p62 + aggresome-bodies. In addition to intracellular-accumulation, we found that CSE also induces membrane-ceramide-accumulation by ROS-dependent acid-sphingomyelinase (ASM) activation and plasma-membrane translocation, which was significantly controlled (p < 0.05) by cysteamine (an anti-oxidant) and amitriptyline (AMT, an inhibitor of ASM). Cysteamine-mediated and CSE-induced membrane-ceramide regulation was nullified by CFTR-inhibitor-172, demonstrating that CFTR controls redox impaired-autophagy dependent membrane-ceramide accumulation. In summary, our data shows that CS-mediated autophagy/lipophagy-dysfunction results in intracellular-ceramide-accumulation, while acquired CFTR-dysfunction-induced ASM causes membrane ceramide-accumulation. Thus, CS-exposure alters the sphingolipid-rheostat leading to the increased membrane- and intracellular- ceramide-accumulation inducing COPD-emphysema pathogenesis that is alleviated by treatment with cysteamine, a potent anti-oxidant with CFTR/autophagy-augmenting properties.

Phenotyping and outcomes of hospitalized COPD patients using rapid molecular diagnostics on sputum samples

Background

Etiologies of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are heterogeneous. We phenotyped severe AECOPD based on molecular pathogen detection of sputum samples collected at hospitalization of COPD patients and determined their outcomes.

Methods

We phenotyped 72 sputum samples of COPD patients who were hospitalized with a primary diagnosis of AECOPD using a molecular array that detected common bacterial and viral respiratory pathogens. Based on these results, the patients were classified into positive or negative pathogen groups. The pathogen-positive group was further divided into virus or bacteria subgroups. Admission day 1 blood samples were assayed for N-terminal prohormone brain natriuretic peptide, CRP, and complete blood counts.

Results

A total of 52 patients had a positive result on the array, while 20 patients had no pathogens detected. The most common bacterial pathogen detected was Haemophilus influenzae and the most common virus was rhinovirus. The pathogen-negative group had the worse outcomes with longer hospital stays (median 6.5 vs 5 days for bacteria-positive group, P=0.02) and a trend toward increased 1-year mortality (P=0.052). The bacteria-positive group had the best prognosis, whereas the virus-positive group had outcomes somewhere in between the bacteria-positive and pathogen-negative groups.

Conclusion

Molecular diagnostics on sputum can rapidly phenotype serious AECOPD into bacteria-, virus-, or pathogen-negative groups. The bacteria-positive group appears to have the best prognosis, while pathogen-negative group has the worst. These data suggest that AECOPD is a heterogeneous event and that accurate phenotyping of AECOPD may lead to novel management strategies that are personalized and more precise.

Inhaled nanomaterials and the respiratory microbiome: clinical, immunological and toxicological perspectives

Our development and usage of engineered nanomaterials has grown exponentially despite concerns about their unfavourable cardiorespiratory consequence, one that parallels ambient ultrafine particle exposure from vehicle emissions. Most research in the field has so far focused on airway inflammation in response to nanoparticle inhalation, however, little is known about nanoparticle-microbiome interaction in the human airway and the environment. Emerging evidence illustrates that the airway, even in its healthy state, is not sterile. The resident human airway microbiome is further altered in chronic inflammatory respiratory disease however little is known about the impact of nanoparticle inhalation on this airway microbiome. The composition of the airway microbiome, which is involved in the development and progression of respiratory disease is dynamic, adding further complexity to understanding microbiota-host interaction in the lung, particularly in the context of nanoparticle exposure. This article reviews the size-dependent properties of nanomaterials, their body deposition after inhalation and factors that influence their fate. We evaluate what is currently known about nanoparticle-microbiome interactions in the human airway and summarise the known clinical, immunological and toxicological consequences of this relationship. While associations between inhaled ambient ultrafine particles and host immune-inflammatory response are known, the airway and environmental microbiomes likely act as intermediaries and facilitate individual susceptibility to inhaled nanoparticles and toxicants. Characterising the precise interaction between the environment and airway microbiomes, inhaled nanoparticles and the host immune system is therefore critical and will provide insight into mechanisms promoting nanoparticle induced airway damage.

Role of Inflammatory Risk Factors in the Pathogenesis of Streptococcus pneumoniae

Streptococcus pneumoniae (Spn) is a colonizer of the human nasopharynx (NP), causing a variety of infections in humans including otitis media, pneumonia, sepsis, and meningitis. The NP is an immune permissive site which allows for the persistence of commensal bacteria. Acute or chronic respiratory airway inflammation constitutes a significant risk factor for the manifestation of Spn infections. The inflammatory conditions caused by an upper respiratory viral infection or respiratory conditions such as allergic asthma and chronic obstructive pulmonary disorders (COPDs) are implicated in the dysregulation of airway inflammation and tissue damage, which compromise the respiratory barrier integrity. These immune events promote bacterial outgrowth leading to Spn dissemination and invasion into the bloodstream. Therefore, suppression of inflammation and restoration of respiratory barrier integrity could contain Spn infections manifesting in the backdrop of an inflammatory disease condition. The gained knowledge could be harnessed in the design of novel therapeutic interventions to circumvent Spn bacterial infections.

Immunological corollary of the pulmonary mycobiome in bronchiectasis: the CAMEB study

Understanding the composition and clinical importance of the fungal mycobiome was recently identified as a key topic in a “research priorities” consensus statement for bronchiectasis.

Patients were recruited as part of the CAMEB study: an international multicentre cross-sectional Cohort of Asian and Matched European Bronchiectasis patients. The mycobiome was determined in 238 patients by targeted amplicon shotgun sequencing of the 18S–28S rRNA internally transcribed spacer regions ITS1 and ITS2. Specific quantitative PCR for detection of and conidial quantification for a range of airway Aspergillus species was performed. Sputum galactomannan, Aspergillus specific IgE, IgG and TARC (thymus and activation regulated chemokine) levels were measured systemically and associated to clinical outcomes.

The bronchiectasis mycobiome is distinct and characterised by specific fungal genera, including Aspergillus, Cryptococcus and Clavispora. Aspergillus fumigatus (in Singapore/Kuala Lumpur) and Aspergillus terreus (in Dundee) dominated profiles, the latter associating with exacerbations. High frequencies of Aspergillus-associated disease including sensitisation and allergic bronchopulmonary aspergillosis were detected. Each revealed distinct mycobiome profiles, and associated with more severe disease, poorer pulmonary function and increased exacerbations.

The pulmonary mycobiome is of clinical relevance in bronchiectasis. Screening for Aspergillus-associated disease should be considered even in apparently stable patients.

The airway mycobiome in bronchiectasis is associated with clinically significant diseasehttp://ow.ly/MCKj30knVrn

Type A Behavior Pattern, Impulsiveness, Risk Propensity, and Empathy as Predictors of Dyspnea and Number of Infections in Men with Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study

BACKGROUND Stress and psychological factors can induce dyspnea in patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to assess selected elements of the clinical presentation of COPD in the context of the severity of type A pattern of behavior, impulsiveness, and tendency for empathy. MATERIAL AND METHODS This was a cross-sectional study. The study group consisted of 179 men with COPD and the control group consisted of 31 healthy male smokers. In all patients, the number of infectious exacerbations over the past year, the result on the dyspnea scale (MRC), and the FEV1-to- predicted FEV1 ratio was assessed. The A pattern of behavior was measured using the Type A scale. To measure impulsivity, risk propensity, and empathy, the IVE impulsivity questionnaire was used. RESULTS An increase in the number of infectious exacerbations was associated with an increased score on the Type A scale, an increase in risk propensity, and a decrease in impulsivity score. Increased severity of dyspnea was associated with an increase in Type A behavior pattern score and an increase in the risk propensity score. CONCLUSIONS Type A behavior pattern and risk propensity are independent predictors of the number of infections in the last year and of the subjective severity of dyspnea among men with COPD and healthy male smokers.

Utility of serum Aspergillus-galactomannan antigen to evaluate the risk of severe acute exacerbation in chronic obstructive pulmonary disease

Background

Recent studies have shown that the microbiome, namely Aspergillus species, play a previously unrecognized role in both stable and exacerbated chronic obstructive pulmonary disease (COPD). Galactomannan is a major component of the Aspergillus cell wall that has been widely used as a diagnostic marker.

Objectives

To explore whether serum levels of Aspergillus-galactomannan antigen could be used to evaluate the risk of severe acute exacerbation of COPD (AE-COPD).

Methods

We measured the Aspergillus-galactomannan antigen levels of 191 patients with stable COPD, and examined its clinical relevance including AE-COPD.

Results

There were 77 (40.3%) patients who were positive for serum Aspergillus-galactomannan antigen (≥0.5). High Aspergillus-galactomannan antigen level (≥0.7) was associated with older age and presence of bronchiectasis and cysts on computed tomography images. Compared to patients with low Aspergillus-galactomannan antigen level (<0.7), patients with high Aspergillus-galactomannan antigen level had significantly higher incidence of severe AE-COPD (P = 0.0039, Gray’s test) and respiratory-related mortality (P = 0.0176, log-rank test). Multivariate analysis showed that high Aspergillus-galactomannan antigen level was independently associated with severe AE-COPD (hazard ratio, 2.162; 95% confidence interval, 1.267−3.692; P = 0.005).

Conclusion

Serum Aspergillus-galactomannan antigen was detected in patients with COPD, and elevated serum Aspergillus-galactomannan antigen was associated with severe AE-COPD.

Granulocyte-CSF links destructive inflammation and comorbidities in obstructive lung disease

Chronic obstructive pulmonary disease (COPD) is an incurable inflammatory lung disease that afflicts millions of people worldwide, and it is the fourth leading cause of death. Systemic comorbidities affecting the heart, skeletal muscle, bone, and metabolism are major contributors to morbidity and mortality. Given the surprising finding in large prospective clinical biomarker studies that peripheral white blood cell count is more closely associated with disease than inflammatory biomarkers, we probed the role of blood growth factors. Using the SHIP-1-deficient COPD mouse model, which manifests a syndrome of destructive lung disease and a complex of comorbid pathologies, we have identified a critical and unexpected role for granulocyte-CSF (G-CSF) in linking these conditions. Deletion of G-CSF greatly reduced airway inflammation and lung tissue destruction, and attenuated systemic inflammation, right heart hypertrophy, loss of fat reserves, and bone osteoporosis. In human clinical translational studies, bronchoalveolar lavage fluid of patients with COPD demonstrated elevated G-CSF levels. These studies suggest that G-CSF may play a central and unforeseen pathogenic role in COPD and its complex comorbidities, and identify G-CSF and its regulators as potential therapeutic targets.

MyD88 as a therapeutic target for inflammatory lung diseases

INTRODUCTION

Myeloid differentiation primary response protein 88 (MyD88) is a critical adaptor protein involved in Toll-like and IL-1 receptor family signaling controlling innate immune responses and inflammation. Genetic deletion of MyD88 function results in profound suppression of inflammation and reduced resistance of the host to pathogens indicating non-redundant roles of MyD88. The TIR domain is critical for MyD88 dimerization and signaling for TLR and IL-1R family receptor. Areas covered: Emerging evidence suggests that chemical disruption of the TIR domain attenuates cell activation and inhibits in vivo MyD88-dependent inflammation. We review the development of MyD88 dimerization disruptors as a novel therapeutic approach of respiratory diseases with a focus on COPD. Expert opinion: There is a proof of concept that therapeutic targeting of MyD88 is feasible and first preclinical data are highly promising. This opens a great opportunity to treat exacerbations of COPD and other chronic respiratory diseases. However, extensive preclinical investigations and risk analyses are required with carefully evaluation of reduced host resistance and opportunistic infections.

The Microbial Endocrinology of Pseudomonas aeruginosa: Inflammatory and Immune Perspectives

Pseudomonas aeruginosa is a major pathogen responsible for both acute and chronic infection. Known as a colonising pathogen of the cystic fibrosis (CF) lung, it is implicated in other settings such as bronchiectasis. It has the ability to cause acute disseminated or localised infection particularly in the immunocompromised. Human hormones have been highlighted as potential regulators of bacterial virulence through crosstalk between analogous "quorum sensing" (QS) systems present in the bacteria that respond to mammalian hormones. Pseudomonas aeruginosa is known to utilise interconnected QS systems to coordinate its virulence and evade various aspects of the host immune system activated in response to infection. Several human hormones demonstrate an influence on P. aeruginosa growth and virulence. This inter-kingdom signalling, termed "microbial endocrinology" has important implications for host-microbe interaction during infection and, potentially opens up novel avenues for therapeutic intervention. This phenomenon, supported by the existence of sexual dichotomies in both microbial infection and chronic lung diseases such as CF is potentially explained by sex hormones and their influence on the infective process. This review summarises our current understanding of the microbial endocrinology of P. aeruginosa, including its endogenous QS systems and their intersection with human endocrinology, pathogenesis of infection and the host immune system.

Electronic cigarettes: One size does not fit all

Electronic cigarettes (ECs) have been growing rapidly in popularity among youth and adults in the United States over the last decade. This increasing prevalence is driven partially by the ability to customize devices, flavors, and nicotine content and the general notion that ECs are harmless, particularly in comparison with conventional cigarettes. In vitro and in vivo murine models have demonstrated a number of harmful biological effects of e-liquids and their aerosols. However, limited clinical data exist on whether these effects translate into detrimental long-term outcomes in human subjects. The short-term harmful respiratory effects of EC use demonstrated in nonsmokers argue against their use. However, slightly more favorable data exist for the respiratory benefits of substituting conventional cigarettes with ECs and the short-term efficacy of ECs as smoking cessation tools. Nonetheless, available research is severely limited in regard to long-term outcomes and by study designs fraught with bias, pointing to the need for additional research efforts with well-designed longitudinal studies to guide US Food and Drug Administration regulatory efforts. The hurdle presented by diverse device designs and e-liquid permutations, which contribute to the inconsistency of available data, also highlights the need for legislative standardization of ECs.

New bacterial growth in bronchial secretions after bronchoscopic valve implantation

Background

Bronchoscopic valve implantation is an established treatment in selected patients with severe lung emphysema. There is evidence in literature of increased bacterial colonization of various implants. So far, it is unclear if an increased bacterial colonization can also be observed after endoscopic valve therapy.

Methods

Retrospective analysis of patients with examination of the bronchial secretions for presence or change of bacterial growth before and after valve implantation.

Results

Overall, 144 patients who underwent bronchoscopic follow-up after valve implantation were included in this analysis. Prior to valve placement, only 7 out of 144 consecutive emphysema patients (5%) presented with evidence of bacterial colonization, whereas 137 patients (95%) showed no bacterial growth prior to valve placement. One hundred seven out of the 137 patients (78%) showed new bacterial growth after valve implantation. Almost 38% of the patients who presented with a new bacterial growth had evidence of Viridans streptococci, Rothia mucilaginousa and Neisseria species simultaneously, as bacterial colonization. Pathogenic bacterial growth was recorded for Staphylococcus aureus (18%), Pseudomonas aeruginosa (13%) and Stenotrophomonas maltophilia (9%) microorganisms. There was also a significant bacterial growth by Moraxella catarrhalis (26%) and anaerobic bacteria (23%), especially in patients with complete atelectasis after successful endoscopic lung volume reduction. For all of the 7 patients, the presented initial bacterial colonization showed a change in the flora after bronchoscopy valve implantation.

Conclusion

In this study we observed an increased bacterial colonization in the long term after valve implantation. This finding needs further evaluation regarding its possible clinical relevance but should be taken into consideration in the follow-up of these patients.

Microbiological airway colonization in COPD patients with severe emphysema undergoing endoscopic lung volume reduction

Background

Endoscopic lung volume reduction (eLVR) is a therapeutic option for selected patients with COPD and severe emphysema. Infectious exacerbations are serious events in these vulnerable patients; hence, prophylactic antibiotics are often prescribed postinterventionally. However, data on the microbiological airway colonization at the time of eLVR are scarce, and there are no evidence-based recommendations regarding a rational antibiotic regimen.

Objective

The aim of this study was to perform a clinical and microbiological analysis of COPD patients with advanced emphysema undergoing eLVR with endobronchial valves at a single German University hospital, 2012–2017.

Patients and methods

Bronchial aspirates were obtained prior to eLVR and sent for microbiological analysis. Antimicrobial susceptibility testing of bacterial isolates was performed, and pathogen colonization was retrospectively compared with clinical parameters.

Results

At least one potential pathogen was found in 47% (30/64) of patients. Overall, Gram-negative bacteria constituted the most frequently detected pathogens. The single most prevalent species were Haemophilus influenzae (9%), Streptococcus pneumoniae (6%), and Staphylococcus aureus (6%). No multidrug resistance was observed, and Pseudomonas aeruginosa occurred in <5% of samples. Patients without microbiological airway colonization showed more severe airflow limitation, hyperinflation, and chronic hypercapnia compared to those with detected pathogens.

Conclusion

Microbiological airway colonization was frequent in patients undergoing eLVR but not directly associated with poorer functional status. Resistance testing results do not support the routine use of antipseudomonal antibiotics in these patients.

The role of acute and chronic respiratory colonization and infections in the pathogenesis of COPD

COPD is a major global concern, increasingly so in the context of ageing populations. The role of infections in disease pathogenesis and progression is known to be important, yet the mechanisms involved remain to be fully elucidated. While COPD pathogens such as Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae are strongly associated with acute exacerbations of COPD (AECOPD), the clinical relevance of these pathogens in stable COPD patients remains unclear. Immune responses in stable and colonized COPD patients are comparable to those detected in AECOPD, supporting a role for chronic colonization in COPD pathogenesis through perpetuation of deleterious immune responses. Advances in molecular diagnostics and metagenomics now allow the assessment of microbe–COPD interactions with unprecedented personalization and precision, revealing changes in microbiota associated with the COPD disease state. As microbial changes associated with AECOPD, disease severity and therapeutic intervention become apparent, a renewed focus has been placed on the microbiology of COPD and the characterization of the lung microbiome in both its acute and chronic states. Characterization of bacterial, viral and fungal microbiota as part of the lung microbiome has the potential to reveal previously unrecognized prognostic markers of COPD that predict disease outcome or infection susceptibility. Addressing such knowledge gaps will ultimately lead to a more complete understanding of the microbe–host interplay in COPD. This will permit clearer distinctions between acute and chronic infections and more granular patient stratification that will enable better management of these features and of COPD.