Stenotrophomonas maltophilia contributes to smoking-related emphysema through IRF1-triggered PANoptosis of alveolar epithelial cells.

Cigarette smoke (CS), the main source of indoor air pollution and the primary risk factor for respiratory diseases, contains chemicals that can perturb microbiota through antibiotic effects. Although smoking induces a disturbance of microbiota in the lower respiratory tract, whether and how it contributes to initiation or promotion of emphysema are not well clarified. Here, we demonstrated an aberrant microbiome in lung tissue of patients with smoking-related COPD. We found that Stenotrophomonas maltophilia (S. maltophilia) was expanded in lung tissue of patients with smoking-related COPD. We revealed that S. maltophilia drives PANoptosis in alveolar epithelial cells and represses formation of alveolar organoids through IRF1 (interferon regulatory factor 1). Mechanistically, IRF1 accelerated transcription of ZBP1 (Z-DNA Binding Protein 1) in S. maltophilia-infected alveolar epithelial cells. Elevated ZBP1 served as a component of the PANoptosome, which triggered PANoptosis in these cells. By using of alveolar organoids infected by S. maltophilia, we found that targeting of IRF1 mitigated S. maltophilia-induced injury of these organoids. Moreover, the expansion of S. maltophilia and the expression of IRF1 negatively correlated with the progression of emphysema. Thus, the present study provides insights into the mechanism of lung dysbiosis in smoking-related COPD, and presents a potential target for mitigation of COPD progression.

Chronic cigarette smoke exposure and pneumococcal infection induce oropharyngeal microbiota dysbiosis and contribute to long-lasting lung damage in mice.

Environmental factors, such as cigarette smoking or lung infections, may influence chronic obstructive pulmonary disease (COPD) progression by modifying the respiratory tract microbiome. However, whether the disease itself induces or maintains dysbiosis remains undefined. In this longitudinal study, we investigated the oropharyngeal microbiota composition and disease progression of mice (in cages of 5-10 mice per cage) before, during and up to 3 months after chronic cigarette smoke exposure or exposure to room air for 6 months. Cigarette smoke exposure induced pulmonary emphysema measurable at the end of exposure for 6 months, as well as 3 months following smoke exposure cessation. Using both classical culture methods and 16S rRNA sequencing, we observed that cigarette smoke exposure altered the relative composition of the oropharyngeal microbiota and reduced its diversity (P <0.001). More than 60 taxa were substantially reduced after 6 months of smoke exposure (P <0.001) However, oropharyngeal microbiota disordering was reversed 3 months after smoke exposure cessation and no significant difference was observed compared to age-matched control mice. The effects of lung infection with Streptococcus pneumoniae on established smoke-induced emphysema and on the oropharyngeal microbiota were also evaluated. Inoculation with S. pneumoniae induced lung damage and altered the microbiota composition for a longer time compared to control groups infected but not previously exposed to smoke (P=0.01). Our data demonstrate effects of cigarette smoke and pneumococcus infection leading to altered microbiota and emphysema development. The reversal of the disordering of the microbiota composition, but not lung damage, following smoke exposure cessation and after clearance of infection suggest that changes in lung structure are not sufficient to sustain a disordered microbiota in mice. Whether changes in the airway microbiota contribute to inducing emphysema requires further investigation.

Virus respiratorio sincitial: no solo bronquiolitis en lactantes / Respiratory syncytial virus: not only bronchiolitis in infants

El neumomediastino espontáneo se define como la presencia de aire dentro del mediastino. Se origina generalmente por una fuga de aire por aumento de presión en el alveolo. La incidencia en la edad pediátrica se encuentra entre 1/8000 y 1/15 000, con dos picos de edad: menores de cuatro años y de entre 13 a 17 años. En el primer grupo suele asociarse a una infección del tracto respiratorio, una crisis asmática o por aspiración de cuerpo extraño, mientras que en el segundo suele originarse tras actividad física intensa. Se ha descrito la implicación de virus como influenza o bocavirus en la fisiopatología de esta entidad, pero hasta el momento muy pocos casos se han descrito en relación con el virus respiratorio sincitial. La clínica más frecuente es dolor torácico junto con disnea y enfisema subcutáneo como signo característico. El diagnóstico en casi todos los casos lo dará la radiografía de tórax. El manejo dependerá del grado de afectación y su repercusión, por lo que variará desde observación hasta ingreso en una Unidad de Cuidados Intensivos. El tratamiento será de soporte y el de las complicaciones asociadas, no se suelen dar recurrencias y el pronóstico suele ser bueno en la mayor parte de los casos

Spontaneous pneumomediastinum is defined as free air or gas contained within the mediastinum. It originates from the rupture of alveolar space because of high pressures. The incidence of spontaneous pneumomediastinum in pediatrics is between 1/8000 to 1/15 000 with two age peaks; under 4 years old and between 13 to 17 years old. First group is characterized by being secondarily accompanied by an infection of the respiratory tract, asthmatic exacerbation or foreign body aspiration while the second one usually originates after intense physical activity. Influenza or bocavirus have been related with the pathology of this entity, but few cases have been written in relation to respiratory syncytial virus. The most common symptoms are chest pain and dyspnea with subcutaneous emphysema as a characteristic sign. Diagnosis in almost all cases will be given by a chest X-ray. Management will depend on the degree of involvement and its repercussion, which will spread from observation to admission to the ICU. Conservative therapy and treatment of associated complications are usually sufficient, there are few recurrences and the prognosis is good in most of cases

Acute COPD exacerbation presenting with pronounced intrabullous haemorrhage and haemoptysis.

A 54-year-old man with history of chronic obstructive pulmonary disease (COPD) presented with subacute onset of chest pain, shortness of breath, productive cough with haemoptysis and night sweats. There were no fever or recent weight loss reported. The chest radiograph showed right upper lobe bullae with adjacent opacification and an emphysematous lung. Due to worsening haemoptysis and persistent chest pain, CT of the chest with contrast was performed, which revealed moderate to severe emphysema and numerous blood-filled bullae. Cardiac work-up for chest pain was negative for myocardial ischaemia and for aortic dissection. Further infectious work-ups for mycobacterial and invasive fungal infection were negative. The patient was treated for acute COPD exacerbation and responded well to the antibiotics with the resolution of haemoptysis. Follow-up CT of the chest revealed the gradual resolution of the haemorrhage, while the patient remained asymptomatic.

Emphysema and bronchiectasis in COPD patients with previous pulmonary tuberculosis: computed tomography features and clinical implications.

Background: Pulmonary tuberculosis (PTB) is a risk factor for COPD, but the clinical characteristics and the chest imaging features (emphysema and bronchiectasis) of COPD with previous PTB have not been studied well. Methods: The presence, distribution, and severity of emphysema and bronchiectasis in COPD patients with and without previous PTB were evaluated by high-resolution computed tomography (HRCT) and compared. Demographic data, respiratory symptoms, lung function, and sputum culture of Pseudomonas aeruginosa were also compared between patients with and without previous PTB. Results: A total of 231 COPD patients (82.2% ex- or current smokers, 67.5% male) were consecutively enrolled. Patients with previous PTB (45.0%) had more severe (p=0.045) and longer history (p=0.008) of dyspnea, more exacerbations in the previous year (p=0.011), and more positive culture of P. aeruginosa (p=0.001), compared with those without PTB. Patients with previous PTB showed a higher prevalence of bronchiectasis (p<0.001), which was more significant in lungs with tuberculosis (TB) lesions, and a higher percentage of more severe bronchiectasis (Bhalla score ≥2, p=0.031), compared with those without previous PTB. The overall prevalence of emphysema was not different between patients with and without previous PTB, but in those with previous PTB, a higher number of subjects with middle (p=0.001) and lower (p=0.019) lobe emphysema, higher severity score (p=0.028), higher prevalence of panlobular emphysema (p=0.013), and more extensive centrilobular emphysema (p=0.039) were observed. Notably, in patients with TB lesions localized in a single lung, no difference was found in the occurrence and severity of emphysema between the 2 lungs. Conclusion: COPD patients with previous PTB had unique features of bronchiectasis and emphysema on HRCT, which were associated with significant dyspnea and higher frequency of severe exacerbations. While PTB may have a local effect on bronchiectasis, its involvement in airspace damage in COPD may be extensive, probably through interactions with cigarette smoke.

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.

Inflammation and chronic colonization of Haemophilus influenzae in sputum in COPD patients related to the degree of emphysema and bronchiectasis in high-resolution computed tomography.

The presence of bacteria in the lower airways in COPD results in inflammation, further airway structural damage, and might lead to repeated exacerbations. We have previously shown that chronic colonization of Haemophilus influenzae during stable disease is related to increased inflammation, and we now aimed to relate previous findings of bacterial colonization and inflammation to the degree of radiological findings of bronchiectasis and emphysema. Thirty-nine patients with COPD were included in their stable state, and a high-resolution computed tomography of the lung was performed. They were followed-up monthly for up to a maximum of 6 months or until exacerbation, and they answered questionnaires, performed spirometry, and induced sputum at every visit. Thirty-five patients had emphysema with an emphysema degree of median 20% (interquartile range 10-50), and five patients had bronchiectasis, of which only four could expectorate sputum. The degree of emphysema correlated with several inflammatory mediators in sputum, such as interleukin-8 concentration, myeloperoxidase activity, and Leukotriene B4 concentration. Ten patients were chronically colonized with H. influenzae (ie, had a positive culture for H. influenzae at all visits). The four sputum patients with bronchiectasis were chronically colonized with H. influenzae and showed higher degree of H. influenzae growth compared to patients without bronchiectasis. During exacerbation, there was no longer any correlation between emphysema degree and inflammation, but patients with bronchiectasis showed higher sputum purulence score than patients without bronchiectasis. Emphysema and bronchiectasis in COPD patients show different clinical features. The presence of emphysema is more related to inflammation, while bronchiectasis is associated with bacterial colonization. We believe that both emphysema and bronchiectasis are therefore COPD phenotypes of highest impact and need evaluation to prevent further disease progression.

Bacteriological incidence in pneumonia patients with pulmonary emphysema: a bacterial floral analysis using the 16S ribosomal RNA gene in bronchoalveolar lavage fluid.

Pulmonary emphysema is an important radiological finding in chronic obstructive pulmonary disease patients, but bacteriological differences in pneumonia patients according to the severity of emphysematous changes have not been reported. Therefore, we evaluated the bacteriological incidence in the bronchoalveolar lavage fluid (BALF) of pneumonia patients using cultivation and a culture-independent molecular method. Japanese patients with community-acquired pneumonia (83) and healthcare-associated pneumonia (94) between April 2010 and February 2014 were evaluated. The BALF obtained from pneumonia lesions was evaluated by both cultivation and a molecular method. In the molecular method, ~600 base pairs of bacterial 16S ribosomal RNA genes in the BALF were amplified by polymerase chain reaction, and clone libraries were constructed. The nucleotide sequences of 96 randomly selected colonies were determined, and a homology search was performed to identify the bacterial species. A qualitative radiological evaluation of pulmonary emphysema based on chest computed tomography (CT) images was performed using the Goddard classification. The severity of pulmonary emphysema based on the Goddard classification was none in 47.4% (84/177), mild in 36.2% (64/177), moderate in 10.2% (18/177), and severe in 6.2% (11/177). Using the culture-independent molecular method, Moraxella catarrhalis was significantly more frequently detected in moderate or severe emphysema patients than in patients with no or mild emphysematous changes. The detection rates of Haemophilus influenzae and Pseudomonas aeruginosa were unrelated to the severity of pulmonary emphysematous changes, and Streptococcus species - except for the S. anginosus group and S. pneumoniae - were detected more frequently using the molecular method we used for the BALF of patients with pneumonia than using culture methods. Our findings suggest that M. catarrhalis is more frequently detected in pneumonia patients with moderate or severe emphysema than in those with no or mild emphysematous changes on chest CT. M. catarrhalis may play a major role in patients with pneumonia complicating severe pulmonary emphysema.

Bone marrow mesenchymal stem cells ameliorate lung injury through anti-inflammatory and antibacterial effect in COPD mice.

The anti-inflammatory and antibacterial mechanisms of bone marrow mesenchymal stem cells (MSCs) ameliorating lung injury in chronic obstructive pulmonary disease (COPD) mice induced by cigarette smoke and Haemophilus Parainfluenza (HPi) were studied. The experiment was divided into four groups in vivo: control group, COPD group, COPD+HPi group, and COPD+HPi+MSCs group. The indexes of emphysematous changes, inflammatory reaction and lung injury score, and antibacterial effects were evaluated in all groups. As compared with control group, emphysematous changes were significantly aggravated in COPD group, COPD+HPi group and COPD+HPi+MSCs group (P<0.01), the expression of necrosis factor-kappaB (NF-κB) signal pathway and proinflammatory cytokines in bronchoalveolar lavage fluid (BALF) were increased (P<0.01), and the phagocytic activity of alveolar macrophages was downregulated (P<0.01). As compared with COPD group, lung injury score, inflammatory cells and proinflammatory cytokines were significantly increased in the BALF of COPD+HPi group and COPD+HPi+MSCs group (P<0.01). As compared with COPD+HPi group, the expression of tumor necrosis factor-α stimulated protein/gene 6 (TSG-6) was increased, the NF-κB signal pathway was depressed, proinflammatory cytokine was significantly reduced, the anti-inflammatory cytokine IL-10 was increased, and lung injury score was significantly reduced in COPD+HPi+MSCs group. Meanwhile, the phagocytic activity of alveolar macrophages was significantly enhanced and bacterial counts in the lung were decreased. The results indicated cigarette smoke caused emphysematous changes in mice and the phagocytic activity of alveolar macrophages was decreased. The lung injury of acute exacerbation of COPD mice induced by cigarette smoke and HPi was alleviated through MSCs transplantation, which may be attributed to the fact that MSCs could promote macrophages into anti-inflammatory phenotype through secreting TSG-6, inhibit NF-кB signaling pathway, and reduce inflammatory response through reducing proinflammatory cytokines and promoting the expression of the anti-inflammatory cytokine. Simultaneously, MSCs could enhance phagocytic activity of macrophages and bacterial clearance. Meanwhile, we detected anti-inflammatory and antibacterial activity of macrophages regulated by MSCs in vitro. As compared with RAW264.7+HPi+CSE group, the expression of NF-кB p65, IL-1ß, IL-6 and TNF-α was significantly reduced, and the phagocytic activity of macrophages was significantly increased in RAW264.7+HPi+CSE+MSCs group (P<0.01). The result indicated the macrophages co-cultured with MSCs may inhibit NF-кB signaling pathway and promote phagocytosis by paracrine mechanism.

Chronic Pseudomonas aeruginosa infection-induced chronic bronchitis and emphysematous changes in CCSP-deficient mice.

The club cell secretory protein (CCSP) is a regulator of lung inflammation following acute respiratory infection or lung injury. Recently, the relationship between CCSP and COPD has been reported. Since COPD results from an abnormal inflammatory response, we hypothesized that CCSP could have a protective role against chronic inflammation-induced lung damage. To address this issue, the pathophysiology of chronic lung inflammation induced by Pseudomonas aeruginosa in CCSP-deficient mice was determined. A tube of 5 mm in length was soaked in a fluid containing P. aeruginosa (PAO01 strain) for 1 week and inserted into the trachea of CCSP-deficient mice. One week later, P. aeruginosa was administered into the trachea. Five weeks after insertion of tube, the mice were sacrificed. Bronchoalveolar lavage fluids were collected to determine the bacterial growth, and the lung histology and physiology were also examined. P. aeruginosa was continuously detected in bronchoalveolar lavage fluids during the study. Neutrophils were increased in the bronchoalveolar lavage fluids from the CCSP-deficient mice in comparison to wild-type mice. A histological study demonstrated chronic inflammation around bronchus, serious bronchial stenosis, and alveolar enlargement in the CCSP-deficient mice. The lung physiology study demonstrated an increase in the lung compliance of the CCSP-deficient mice. Chronic P. aeruginosa inflammation resulted in chronic bronchitis and emphysematous changes in the CCSP-deficient mice. CCSP could play an important role in protecting the host from the chronic inflammation-induced lung damage.

Airway bacteria drive a progressive COPD-like phenotype in mice with polymeric immunoglobulin receptor deficiency.

Mechanisms driving persistent airway inflammation in chronic obstructive pulmonary disease (COPD) are incompletely understood. As secretory immunoglobulin A (SIgA) deficiency in small airways has been reported in COPD patients, we hypothesized that immunobarrier dysfunction resulting from reduced SIgA contributes to chronic airway inflammation and disease progression. Here we show that polymeric immunoglobulin receptor-deficient (pIgR(-/-)) mice, which lack SIgA, spontaneously develop COPD-like pathology as they age. Progressive airway wall remodelling and emphysema in pIgR(-/-) mice are associated with an altered lung microbiome, bacterial invasion of the airway epithelium, NF-κB activation, leukocyte infiltration and increased expression of matrix metalloproteinase-12 and neutrophil elastase. Re-derivation of pIgR(-/-) mice in germ-free conditions or treatment with the anti-inflammatory phosphodiesterase-4 inhibitor roflumilast prevents COPD-like lung inflammation and remodelling. These findings show that pIgR/SIgA deficiency in the airways leads to persistent activation of innate immune responses to resident lung microbiota, driving progressive small airway remodelling and emphysema.

Novel aspects of pathogenesis and regeneration mechanisms in COPD.

Chronic obstructive pulmonary disease (COPD), a major cause of death and morbidity worldwide, is characterized by expiratory airflow limitation that is not fully reversible, deregulated chronic inflammation, and emphysematous destruction of the lungs. Despite the fact that COPD is a steadily growing global healthcare problem, the conventional therapies remain palliative, and regenerative approaches for disease management are not available yet. We aim to provide an overview of key reviews, experimental, and clinical studies addressing lung emphysema development and repair mechanisms published in the past decade. Novel aspects discussed herein include integral revision of the literature focused on lung microflora changes in COPD, autoimmune component of the disease, and environmental risk factors other than cigarette smoke. The time span of studies on COPD, including emphysema, chronic bronchitis, and asthmatic bronchitis, covers almost 200 years, and several crucial mechanisms of COPD pathogenesis are described and studied. However, we still lack the holistic understanding of COPD development and the exact picture of the time-course and interplay of the events during stable, exacerbated, corticosteroid-treated COPD states, and transitions in-between. Several generally recognized mechanisms will be discussed shortly herein, ie, unregulated inflammation, proteolysis/antiproteolysis imbalance, and destroyed repair mechanisms, while novel topics such as deviated microbiota, air pollutants-related damage, and autoimmune process within the lung tissue will be discussed more extensively. Considerable influx of new data from the clinic, in vivo and in vitro studies stimulate to search for novel concise explanation and holistic understanding of COPD nowadays.

Extracellular vesicles derived from Gram-negative bacteria, such as Escherichia coli, induce emphysema mainly via IL-17A-mediated neutrophilic inflammation.

Recent evidence indicates that Gram-negative bacteria-derived extracellular vesicles (EVs) in indoor dust can evoke neutrophilic pulmonary inflammation, which is a key pathology of chronic obstructive pulmonary disease (COPD). Escherichia coli is a ubiquitous bacterium present in indoor dust and secretes nanometer-sized vesicles into the extracellular milieu. In the current study, we evaluated the role of E. coli-derived EVs on the development of COPD, such as emphysema. E. coli EVs were prepared by sequential ultrafiltration and ultracentrifugation. COPD phenotypes and immune responses were evaluated in C57BL/6 wild-type (WT), IFN-γ-deficient, or IL-17A-deficient mice after airway exposure to E. coli EVs. The present study showed that indoor dust from a bed mattress harbors E. coli EVs. Airway exposure to E. coli EVs increased the production of proinflammatory cytokines, such as TNF-α and IL-6. In addition, the repeated inhalation of E. coli EVs for 4 wk induced neutrophilic inflammation and emphysema, which are associated with enhanced elastase activity. Emphysema and elastase activity enhanced by E. coli EVs were reversed by the absence of IFN-γ or IL-17A genes. In addition, during the early period, lung inflammation is dependent on IL-17A and TNF-α, but not on IFN-γ, and also on TLR4. Moreover, the production of IFN-γ is eliminated by the absence of IL-17A, whereas IL-17A production is not abolished by IFN-γ absence. Taken together, the present data suggest that E. coli-derived EVs induce IL-17A-dependent neutrophilic inflammation and thereby emphysema, possibly via upregulation of elastase activity.

Triple opportunistic pulmonary cavitary disease after cord blood transplantation.

Opportunistic infectious diseases in patients are variable and depend on the host as well as the type of immunosuppression. Cord blood transplant recipients appear to be particularly vulnerable to infectious complications. Sequential or concurrent opportunistic infectious diseases can be particularly difficult to manage and have increased mortality. We present a young patient, status post cord blood transplantation for acute myelogenous leukemia, who developed a large pulmonary mass-like infection with Aspergillus, cytomegalovirus, and Mycobacterium avium complex. Radiological, surgical, and pathological features are described.

MRSA infected emphysematous bullae in an asymptomatic COPD patient.

This is a case of a 57-year-old gentleman with a history of chronic obstructive pulmonary disease (COPD) who presented with diarrhoea of more than 4 weeks in length. On chest x-ray, he was incidentally found to have a large cavitating lesion in his right lung. He denied having any respiratory distress at any stage and clinically he had been completely asymptomatic. The CT-guided biopsy confirmed a methicillin-resistant Staphylococcus aureus positive lung cavitation, most likely secondary to his poor dentition. A full dental clearance was performed, and he was treated with a course of intravenous vancomycin and oral clindamycin with good effect.

Elastase/LPS-exposed mice exhibit impaired innate immune responses to bacterial challenge: role of scavenger receptor A.

Nontypeable Haemophilus influenzae (NTHi) is an important bacterial pathogen associated with lower respiratory tract colonization and with acute exacerbations and disease progression in chronic obstructive pulmonary disease (COPD). Why the immune system fails to eliminate NTHi and the exact contribution of the organism to COPD progression are not well understood, in part because we lack an animal model that mimics all aspects of COPD. For this study, we used an established murine model that exhibits typical features of COPD. Elastase/LPS-exposed mice infected with NTHi showed persistence of bacteria up to 5 days after infection, whereas mice exposed to elastase, LPS, or PBS cleared all bacteria by 3 days. Elastase/LPS-exposed mice also showed sustained lung neutrophilic inflammation, goblet cell metaplasia, airway hyperresponsiveness, and progression of emphysema at 15 days after infection. Alveolar macrophages isolated from elastase/LPS-exposed mice showed impaired bacterial phagocytosis, reduced expression of MARCO and of mannose receptor, and absent expression of scavenger receptor-A (SR-A). Neutralization of SR-A significantly decreased phagocytosis of NTHi by normal alveolar macrophages. Our results suggest that elastase/LPS-exposed mice show impaired bacterial clearance and sustained lung inflammation. Lack of SR-A expression may, in part, be responsible for impaired phagocytosis of bacteria by alveolar macrophages of elastase/LPS-exposed mice. These data validate the suitability of elastase/LPS model for investigating NTHi pathogenesis and progression of disease in COPD.

Experimental pulmonary infection and colonization of Haemophilus influenzae in emphysematous hamsters.

BACKGROUND: Bacterial infection has been considered the main cause of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). However, experimental model of COPD exacerbation induced by Haemophilus influenzae infection was not available up to now. Furthermore, only a few studies on evaluation of antibiotics using an H. influenzae infection model in mice have been reported. The aim of this work was to evaluate the activity of moxifloxacin on experimental pulmonary infection and colonization of H. influenzae in emphysematous hamsters. METHODS: Pulmonary emphysema was developed by intratracheal instillation of porcine pancreatic elastase in golden hamsters, which were infected by agar-beads enclosing H. influenzae to establish animal models of AECOPD. Alterations of lung histopathology, inflammatory factor levels in plasma and bronchoalveolar lavage fluids (BALFs), viable cell counting of lung tissue were determined on different days after challenge and moxifloxacin administration. RESULTS: Lung bacterial counts of BALFs and homogenates were significantly higher in emphysematous hamsters than those in normal non-emphysematous animals from 1 to 3 weeks after intratracheal inoculation of bacterial agar-beads suspensions. Moreover, H. influenzae colonized and survived for a longer period of time in emphysematous lungs than in normal non-emphysematous lungs after challenge. Efficacy of 3-day intragastric administration of moxifloxacin was proved by reduction in pulmonary H. influenzae burden and alleviation of inflammatory responses on days 4, 8 and 21 post-inoculation. No planktonic bacteria were isolated from BALFs in the first week after moxifloxacin treatment, and bacterial load in lung tissue homogenates declined significantly. Nevertheless, after 3 weeks, bacterial load in BALFs and homogenates of emphysematous lungs recovered to a large quantity. Inflammation in lung tissue, including lung consolidation, hemorrhage, and neutrophils infiltration, was conspicuously improved after administration of moxifloxacin. Levels of inflammatory factors in plasma were significantly decreased on days 8 and 21 after treatment compared with that without drug therapy. Inflammatory factors in BALF were also reduced, among which IL-8 dropped down markedly in early stage. CONCLUSION: Our results suggest that chronic bacterial infection and colonization is highly correlated with lung emphysematous lesions, which would be one of the important mechanisms for repeated attacks of acute exacerbations of chronic pulmonary diseases and uncertain efficacies of antibiotics.