Lung Microbiota and Pulmonary Inflammatory Cytokines Expression Vary in Children With Tracheomalacia and Adenoviral or Mycoplasma pneumoniae Pneumonia

Cytokine-based nomogram for discriminating viral pneumonia from Mycoplasma pneumoniae pneumonia in children

For children with pneumonia, differential diagnosis between viral infection and Mycoplasma pneumoniae (MP) infection is difficult. We retrospectively enrolled 336 hospitalized children who were diagnosed with community-acquired pneumonia and whose infection was exclusively viral or MP. We analyzed hematological indicators, biochemical markers, and cytokines. Least absolute shrinkage and selection operator (LASSO) regression analysis and logistic regression analysis were performed to identify and validate the factors that predicted the pathogenic diagnosis. The final predictive model incorporated four factors: tumor necrosis factor-α/interleukin (IL)-10, age, IL-8 and procalcitonin. This predictive model was visualized with a nomogram and had good performance. Using logistic regression analysis, the C-index of this predictive model was 0.878. Using receiver operating characteristic plot, the area under the curve was 0.8785. We established a model with a nomogram to discriminate viral infection from MP infection in hospitalized children with community-acquired pneumonia.

Azithromycin sequential therapy plus inhaled terbutaline for Mycoplasma Pneumoniae pneumonia in children: a systematic review and meta-analysis

BACKGROUND

An improper host immune response to Mycoplasma pneumoniae generates excessive inflammation, which leads to the impairment of pulmonary ventilation function (PVF). Azithromycin plus inhaled terbutaline has been used in the treatment of Mycoplasma pneumoniae pneumonia (MPP) in children with impaired pulmonary function, but previous randomized controlled trials (RCTs) showed inconsistent efficacy and safety. This study is aimed to firstly provide a systematic review of the combined therapy.

METHODS

This study was registered at the International Prospective Register of Systematic Reviews (PROSPERO CRD42023452139). A PRISMA-compliant systematic review and meta-analysis was performed. Six English and four Chinese databases were comprehensively searched up to June, 2023. RCTs of azithromycin sequential therapy plus inhaled terbutaline were selected. The revised Cochrane risk of bias tool for randomized trials (RoB2) was used to evaluate the methodological quality of all studies, and meta-analysis was performed using Stata 15.0 with planned subgroup and sensitivity analyses. Publication bias was evaluated by a funnel plot and the Harbord' test. Certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation recommendations.

RESULTS

A total of 1,938 pediatric patients from 20 RCTs were eventually included. The results of meta-analysis showed that combined therapy was able to significantly increase total effectiveness rate (RR = 1.20, 95%CI 1.15 to 1.25), forced expiratory volume in one second (SMD = 1.14, 95%CIs, 0.98 to 1.29), the ratio of forced expiratory volume in one second/forced vital capacity (SMD = 2.16, 95%CIs, 1.46 to 2.86), peak expiratory flow (SMD = 1.17, 95%CIs, 0.91 to 1.43). The combined therapy was associated with a 23% increased risk of adverse reactions compared to azithromycin therapy alone, but no significant differences were found. Harbord regression showed no publication bias (P = 0.148). The overall quality of the evidence ranged from moderate to very low.

CONCLUSIONS

This first systematic review and meta-analysis suggested that azithromycin sequential therapy plus inhaled terbutaline was safe and beneficial for children with MPP. In addition, the combined therapy represented significant improvement of PVF. Due to lack of high-quality evidence, our results should be confirmed by adequately powered RCTs in the future.

Clinical significance of measuring MP-DNA, C-reactive protein, and inflammatory cytokines in children with mycoplasma pneumoniae pneumonia

OBJECTIVE

To explore the clinical significance of detecting mycoplasma pneumoniae (MP)-DNA, C-reactive protein (CRP), interleukin-6 (IL-6), IL-8, and IL-10 in children with mycoplasma pneumoniae pneumonia (MPP).

METHODS

The data from 106 children who received treatment or underwent health examination in the Children's Medical Center of Anhui Medical University from January 2021 to October 2022 were collected and analyzed retrospectively. The observation group (OG) consisted of 64 children with MPP, while the control group (CG) consisted of 42 healthy children. The levels of IL-6, IL-8, IL-10, CRP, and MP-DNA were compared between the two groups. The diagnostic value of MP-DNA in patients with MPP and its correlation with the levels of IL-6, IL-8, IL-10 and CRP were analyzed.

RESULTS

The level of MP-DNA in the OG was notably higher than that in the CG (P<0.05). Additionally, the levels of IL-6, IL-8, IL-10, and CRP in the OG were significantly higher than those in the CG (P<0.05). MP-DNA was positively correlated with the levels of IL-6, IL-8, IL-10, and CRP (P<0.05). The area under the curve of MP-DNA in diagnosing MPP was 0.979, with a specificity of 92.19% and a sensitivity of 97.62%.

CONCLUSION

Indicators such as MP-DAN, IL-6, IL-8 are crucial in the development and progression of MPP, playing an important role in diagnosing and treating patients with MPP.

The Respiratory Microbiome in Paediatric Chronic Wet Cough: What Is Known and Future Directions

Chronic wet cough for longer than 4 weeks is a hallmark of chronic suppurative lung diseases (CSLD), including protracted bacterial bronchitis (PBB), and bronchiectasis in children. Severe lower respiratory infection early in life is a major risk factor of PBB and paediatric bronchiectasis. In these conditions, failure to clear an underlying endobronchial infection is hypothesised to drive ongoing inflammation and progressive tissue damage that culminates in irreversible bronchiectasis. Historically, the microbiology of paediatric chronic wet cough has been defined by culture-based studies focused on the detection and eradication of specific bacterial pathogens. Various 'omics technologies now allow for a more nuanced investigation of respiratory pathobiology and are enabling development of endotype-based models of care. Recent years have seen substantial advances in defining respiratory endotypes among adults with CSLD; however, less is understood about diseases affecting children. In this review, we explore the current understanding of the airway microbiome among children with chronic wet cough related to the PBB-bronchiectasis diagnostic continuum. We explore concepts emerging from the gut-lung axis and multi-omic studies that are expected to influence PBB and bronchiectasis endotyping efforts. We also consider how our evolving understanding of the airway microbiome is translating to new approaches in chronic wet cough diagnostics and treatments.

Analysis of cytokine levels, cytological findings, and MP-DNA level in bronchoalveolar lavage fluid of children with Mycoplasma pneumoniae pneumonia

BACKGROUND

The present study was conducted to determine the inflammatory response in the lungs of children with Mycoplasma pneumoniae pneumonia (MPP).

METHODS

This study retrospectively analyzed cytokine levels, cytological findings, and M. pneumoniae (MP)-DNA level in the bronchoalveolar lavage fluid (BALF) of 96 children with MPP. The study utilized Spearman's correlation method to evaluate the contribution of BALF and blood parameters in MPP children.

RESULTS

(1) A total of 96 MPP children were classified into the Low MP-DNA MPP group (BALF MP-DNA ≤ 105 copies/mL) and the High MP-DNA MPP group (BALF MP-DNA > 105 copies/mL); the Non-fever MPP group (no fever during the entire course of pneumonia) and the Fever MPP group; the Defervescence MPP group (fever had subsided at the time of bronchoscopy) and the Fervescence MPP group; and the Mild MPP group and the Severe MPP group. (2) The High MP-DNA MPP, Fever MPP, Fervescence MPP, and Severe MPP groups had higher levels of interleukin (IL)-6, IL-10, and tumor necrosis factor-α (TNF-α) in their BALF (all p < .05). (3) The proportions of neutrophils and macrophages in the BALF of the High MP-DNA MPP and Fever MPP groups increased and decreased, respectively (all p < .05). (4) In the BALF of MPP children, MP-DNA, IL-6, IL-10, TNF-α, and interferon gamma (IFN-γ) levels positively correlated with neutrophil proportion while negatively correlated with macrophage proportion (all p < .05). (5) The MP-DNA, IL-6, IL-10, TNF-α, and IFN-γ levels in the BALF of MPP children were positively correlated with the levels of C-reactive protein, procalcitonin, lactic dehydrogenase, fibrinogen, and d-dimer, while they were negatively correlated with the albumin level (all p < .05).

CONCLUSIONS

In children with MPP, the pulmonary inflammatory immune response was stronger in the High MP-DNA MPP, Fever MPP, Fervescence MPP, and Severe MPP groups. The relationship between pulmonary cytokine levels, MP-DNA load, and serum inflammatory parameters were found to be weak.

Construction and analysis of a nomogram prediction model for post-infectious bronchiolitis obliterans in children with adenovirus pneumonia after invasive mechanical ventilation

BACKGROUND

Post-infectious bronchiolitis obliterans (PIBO) is the most common sequelae in children with adenovirus pneumonia (ADVP). However, there are few studies on the risk factors for PIBO occurrence. This study aims to investigate the risk factors for PIBO in pediatric patients with severe ADVP, especially after invasive mechanical ventilation (IMV), as well as to build a nomogram prediction model.

METHODS

The clinical data, laboratory and imaging features, and treatment of 863 children with ADVP under 3 years old who were admitted to our hospital from January to December 2019 were retrospectively analyzed. Among them, 66 children with severe ADVP received IMV treatment. The situation and the influencing factors of PIBO in children with severe ADVP were explored, and a nomogram prediction model was constructed.

RESULTS

Among the 863 cases of ADVP, 46 cases (5.33%) developed PIBO. Duration of fever, IMV, complications, and neutrophil percentage were independent risk factors for PIBO in children with ADVP. Among the 66 patients with ADVP who underwent IMV, 33 patients (50.0%) developed PIBO. Gender, duration of fever, adenovirus (ADV) load, and mixed fungal coinfections were independent risk factors for PIBO. In the nomogram prediction model analysis, the area under the curve (AUC) was 0.857; in addition, Hosmer‒Lemeshow (H-L) detection reflected good alignment (χ2 = 68.75, P < 0.01).

CONCLUSIONS

A nomogram prediction model, which can be utilized to predict PIBO occurrence in pediatric patients with ADVP after IMV at an early time period, was successfully built.

Diagnostic and Prognostic Value of Dysregulated miR-10a-3p in Patients with Severe Pneumonia

PURPOSE

Previous studies have shown that microRNA is involved in regulating a variety of human inflammatory diseases. The purpose of this study was to investigate the expression of miR-10a-3p in the blood of patients with severe pneumonia and evaluate its value in the diagnosis and prognosis of severe pneumonia.

PATIENTS AND METHODS

Seventy patients with severe pneumonia and 75 healthy individuals were included in this study. Venous blood of all subjects was obtained for RT-qPCR analysis to obtain the relative expression level of miR-10a-5p. The diagnostic accuracy of miR-10a-5p for severe pneumonia was assessed by ROC curve. After standardized treatment, the prognosis of patients with severe pneumonia was analyzed by a 28-day follow-up method. Kaplan-Meier curve and multivariate Cox regression analysis were used to determine the basic factors influencing the prognosis of patients.

RESULTS

Compared with healthy control, serum miR-10a-3p expression in patients with severe pneumonia was distinctly upregulated (P < 0.001). Besides, ROC analysis showed that miR-10a-3p had high diagnostic accuracy for severe pneumonia, with an AUC of 0.881, sensitivity and specificity of 75.7% and 84.0%, respectively. Kaplan-Meier curve exhibited that high miR-10a-3p expression group had a higher probability of death than those with low miR-10a-3p expression. Multivariate Cox regression analysis demonstrated that miR-10a-3p and CRP were independent risk factors affecting the prognosis of patients.

CONCLUSION

The expression of miR-10a-3p was increased in patients with severe pneumonia, and abnormally expressed miR-10a-3p has the potential to be used as a diagnostic and prognostic marker for severe pneumonia, which provides a new biological direction for the early detection and risk assessment of severe pneumonia.

Development of a model for early differentiation of adenovirus pneumonia from Mycoplasma pneumoniae pneumonia

BACKGROUND

Adenovirus pneumonia (AVP) and Mycoplasma pneumoniae pneumonia (MPP) have similar clinical manifestations such as a high prevalence of lung consolidation, making the differential diagnosis difficult before the etiology is reported. This study aimed to compare AVP and MPP, and to build a predictive model to differentiate them early.

METHODS

We selected 198 cases of AVP and 876 cases of MPP. Clinical manifestations, computed tomography (CT) features, and biomarkers were compared. A logistic regression model was built to predict AVP. The area under the curve (AUC) of the receiver-operating characteristic was calculated to evaluate the discriminant ability of the prediction model.

RESULTS

Patients in the AVP group were mainly infants and toddlers, while the MPP group had more pre-school age children. The rate of hypoxemia and severe pneumonia was 3- and 11-times higher, respectively, in the AVP group than in the MPP group (5.6% vs. 1.8%, 27.8% vs. 2.5%, P<0.01). The proportion of patients with a Pediatric Logistic Organ Dysfunction-2 score ≥2 was 10 times higher in the AVP group than in the MPP group (17.4% vs. 1.7%, P<0.01). Bilateral pneumonia was present in 90.2% of the AVP group. Biomarkers, such as interleukin (IL)-2 receptor, IL-10 and lactic dehydrogenase (LDH), were considerably higher in the AVP group than in the MPP group (P<0.01). The predictive model included eight variables, namely: age, severe pneumonia, bilateral pneumonia, ground-glass attenuation, consolidation, atelectasis, C-reactive protein, and LDH. The AUC was 86.6%.

CONCLUSIONS

Compared with MPP, AVP affects younger children, presents a more severe respiratory tract involvement, results in a larger range of lung lesions, and is associated with higher inflammatory biomarkers. Our predictive model includes a combination of clinical features, imaging findings, and biomarkers. It may help pediatricians in the early differentiation of AVP from MPP.

Clinical analysis of the epidemiology and changes in inflammatory indexes of Mycoplasma pneumonia in acute and recovery stage pediatric patients

BACKGROUND

As Mycoplasma pneumoniae pneumonia (MPP) is on the rise in children and adolescents, this work explored the clinical analysis of epidemiological and inflammatory changes in children with MPP during the acute and convalescent phases, and analyzed their relationship with clinical manifestations.

METHODS

One hundred and twenty MP patients (experimental group) and 100 healthy children (control group) were selected as the research objects. Enzyme-linked immunosorbent assay (ELISA) was used to detect the changes in tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10) and procalcitonin (PCT).

RESULTS

The proportion of children aged 3-7 years was significantly higher than that of other age groups (0-1, 1-3, and 7-14 years old) (P<0.05). The serum levels of TNF-α, IL-6, IL-8, IL-10, and PCT in children with MP were significantly higher than those in the control group (P<0.05). Changes in pulmonary fibrosis and serum and pleural fluid TNF-α, IL-6, IL-8, IL-10, and PCT concentrations on chest X-ray and computed tomography (CT) in children with MP with pleural effusion significantly higher than that in children without pulmonary fibrosis (P<0.05).

CONCLUSIONS

MPP was more common in children aged 3-7 years. In addition, the changes of inflammatory markers TNF-α, IL-6, IL-8, IL-10, and PCT in serum and pleural effusion of children with MP were of great value for the diagnosis, treatment, and prognosis of the disease.

Effect of invasive mechanical ventilation on the diversity of the pulmonary microbiota

Pulmonary microbial diversity may be influenced by biotic or abiotic conditions (e.g., disease, smoking, invasive mechanical ventilation (MV), etc.). Specially, invasive MV may trigger structural and physiological changes in both tissue and microbiota of lung, due to gastric and oral microaspiration, altered body posture, high O2 inhalation-induced O2 toxicity in hypoxemic patients, impaired airway clearance and ventilator-induced lung injury (VILI), which in turn reduce the diversity of the pulmonary microbiota and may ultimately lead to poor prognosis. Furthermore, changes in (local) O2 concentration can reduce the diversity of the pulmonary microbiota by affecting the local immune microenvironment of lung. In conclusion, systematic literature studies have found that invasive MV reduces pulmonary microbiota diversity, and future rational regulation of pulmonary microbiota diversity by existing or novel clinical tools (e.g., lung probiotics, drugs) may improve the prognosis of invasive MV treatment and lead to more effective treatment of lung diseases with precision.

Vaccination with Mycoplasma pneumoniae membrane lipoproteins induces IL-17A driven neutrophilia that mediates Vaccine-Enhanced Disease

Bacterial lipoproteins are an often-underappreciated class of microbe-associated molecular patterns with potent immunomodulatory activity. We previously reported that vaccination of BALB/c mice with Mycoplasma pneumoniae (Mp) lipid-associated membrane proteins (LAMPs) resulted in lipoprotein-dependent vaccine enhanced disease after challenge with virulent Mp, though the immune responses underpinning this phenomenon remain poorly understood. Herein, we report that lipoprotein-induced VED in a mouse model is associated with elevated inflammatory cytokines TNF-α, IL-1β, IL-6, IL-17A, and KC in lung lavage fluid and with suppurative pneumonia marked by exuberant neutrophilia in the pulmonary parenchyma. Whole-lung-digest flow cytometry and RNAScope analysis identified multiple cellular sources for IL-17A, and the numbers of IL-17A producing cells were increased in LAMPs-vaccinated/Mp-challenged animals compared to controls. Specific IL-17A or neutrophil depletion reduced disease severity in our VED model—indicating that Mp lipoproteins induce VED in an IL-17A-dependent manner and through exuberant neutrophil recruitment. IL-17A neutralization reduced levels of TNF-α, IL-1β, IL-6, and KC, indicating that IL-17A preceded other inflammatory cytokines. Surprisingly, we found that IL-17A neutralization impaired bacterial clearance, while neutrophil depletion improved it—indicating that, while IL-17A appears to confer both maladaptive and protective responses, neutrophils play an entirely maladaptive role in VED. Given that lipoproteins are found in virtually all bacteria, the potential for lipoprotein-mediated maladaptive inflammatory responses should be taken into consideration when developing vaccines against bacterial pathogens.

Probiotics, prebiotics, and synbiotics to prevent or combat air pollution consequences: The gut-lung axis

Air pollution exposure is a public health emergency, which attributes globally to an estimated seven million deaths on a yearly basis We are all exposed to air pollutants, varying from ambient air pollution hanging over cities to dust inside the home. It is a mixture of airborne particulate matter and gases that can be subdivided into three categories based on particle diameter. The smallest category called PM_0.1 is the most abundant. A fraction of the particles included in this category might enter the blood stream spreading to other parts of the body. As air pollutants can enter the body via the lungs and gut, growing evidence links its exposure to gastrointestinal and respiratory impairments and diseases, like asthma, rhinitis, respiratory tract infections, Crohn's disease, ulcerative colitis, and abdominal pain. It has become evident that there exists a crosstalk between the respiratory and gastrointestinal tracts, commonly referred to as the gut-lung axis. Via microbial secretions, metabolites, immune mediators and lipid profiles, these two separate organ systems can influence each other. Well-known immunomodulators and gut health stimulators are probiotics, prebiotics, together called synbiotics. They might combat air pollution-induced systemic inflammation and oxidative stress by optimizing the microbiota composition and microbial metabolites, thereby stimulating anti-inflammatory pathways and strengthening mucosal and epithelial barriers. Although clinical studies investigating the role of probiotics, prebiotics, and synbiotics in an air pollution setting are lacking, these interventions show promising health promoting effects by affecting the gastrointestinal- and respiratory tract. This review summarizes the current data on how air pollution can affect the gut-lung axis and might impact gut and lung health. It will further elaborate on the potential role of probiotics, prebiotics and synbiotics on the gut-lung axis, and gut and lung health.

Characteristics of Lung Microbiota in Children's Refractory Mycoplasma pneumoniae Pneumonia Coinfected with Human Adenovirus B

Background

Both M. pneumoniae and human adenovirus (HAdV) are common causative agents of lower respiratory tract infection in children; nonetheless, the lung microbiota in patients with coinfection of HAdV and M. pneumoniae remain unexplored.

Methods

Thirty-two children, diagnosed with refractory M. pneumoniae pneumonia (RMPP), entered into the one-year study from July 1, 2019 to June 30, 2020. Among them, twenty-one entered into the M. pneumoniae monoinfection (MP) group and eleven entered into the M. pneumoniae and HAdV coinfection (MP&ADV) group. The characteristics of the clinical findings were examined, and the lung microbiota was analyzed by metagenomic next generation sequencing (mNGS).

Results

Eleven patients in the MP&ADV group were coinfected with human mastadenovirus species B. The fever days lasted for significantly longer periods in the MP&ADV group than in the MP group (P < 0.05). The percentage of CD16⁺CD56⁺ cells was significantly higher in the MP&ADV group than that in the MP group (P < 0.05). There were no significant differences in α-diversity between the MP and MP&ADV groups, but the β-diversity was clearly higher in the MP&ADV group than that in the MP group (P < 0.05). At the microbial level, the top phylum of the MP BALF microbiota was Tenericutes; in contrast, it was Preplasmiviricota in the MP&ADV BALF. There were significant differences in the relative abundance of Tenericutes and Preplasmiviricota between the two groups (P < 0.001). There was a strong positive correlation between human mastadenovirus B and fever days, M. pneumoniae and level of IgA, and a strong negative correlation between Mycoplasma pneumoniae and PCT.

Conclusions

In RMPP, the BALF microbiota in children with mono M. pneumoniae infection was simpler than those with coinfection with human mastadenovirus B. Prolonged fever days were associated with human mastadenovirus B coinfection.

Airway Malacia: Clinical Features and Surgical Related Issues, a Ten-Year Experience from a Tertiary Pediatric Hospital

Background: Few studies have been carried out with the aim of describing the clinical course and follow-up of patients with tracheomalacia. We aim to describe the symptoms at diagnosis and the post-treatment clinical course of patients affected by airway malacia. Methods: We retrospectively analyzed characteristics of pediatric patients with a diagnosis of airway malacia. Patients were classified into three groups: bronchomalacia (BM), tracheomalacia (TM) and tracheo-bronchomalacia (TBM). Demographic and clinical data, diagnostic work-up and surgical treatment were recorded. Results: 13/42 patients were affected by congenital syndromes (30.9%). Esophageal atresia with or without tracheal-esophageal fistula (EA/TEF) was detected in 7/42 patients (16.7%). Cardiovascular anomalies were found in 9/42 (21.4%) and idiopathic forms in 13/42 (30.9%). BM occurred in 7/42 (16.6%), TM in 23/42 (54.7%) and TBM in 12/42 (28.6%). At the diagnosis stage, a chronic cough was reported in 50% of cases with a higher prevalence in EA/TEF (p = 0.005). Surgery was performed in 16/42 (40%) of children. A chronic cough and acute respiratory failure were correlated to the need for surgery. During follow-up, there was no difference in persistence of symptoms between conservative vs surgical treatment (p = 0.47). Conclusion: the management of tracheomalacia remains a challenge for pediatricians. Clinical manifestations, such as a barking cough and acute respiratory failure may suggest the need for surgery. Follow-up is crucial, especially in those patients affected by comorbidities, so as to be able to manage effectively the possible persistence of symptoms, including those that may continue after surgical treatment.

SSRIs: Applications in inflammatory lung disease and implications for COVID-19

Selective serotonin reuptake inhibitors (SSRIs) have anti-inflammatory properties that may have clinical utility in treating severe pulmonary manifestations of COVID-19. SSRIs exert anti-inflammatory effects at three mechanistic levels: (a) inhibition of proinflammatory transcription factor activity, including NF-κB and STAT3; (b) downregulation of lung tissue damage and proinflammatory cell recruitment via inhibition of cytokines, including IL-6, IL-8, TNF-α, and IL-1β; and (c) direct suppression inflammatory cells, including T cells, macrophages, and platelets. These pathways are implicated in the pathogenesis of COVID-19. In this review, we will compare the pathogenesis of lung inflammation in pulmonary diseases including COVID-19, ARDS, and chronic obstructive pulmonary disease (COPD), describe the anti-inflammatory properties of SSRIs, and discuss the applications of SSRIS in treating COVID-19-associated inflammatory lung disease.

Biological functions of IL-17-producing cells in mycoplasma respiratory infection

Mycoplasmas are the smallest and simplest bacteria that lack a cell wall but have the capability of self-replication. Among them, Mycoplasma pneumoniae is one of the most common causes of community-acquired pneumonia. The hallmark of mycoplasma respiratory diseases is the persistence of lung inflammation that involves both innate and adaptive immune responses. In recent years, a growing body of evidence demonstrates that IL-17 plays an important role in respiratory mycoplasma infection, and associates with the pathologic outcomes of infection, such as pneumonitis and asthma. Numerous studies have shown that a variety of cells, in particular Th17 cells, in the lung can secrete IL-17 during respiratory mycoplasma infection. In this article, we review the biological functions of distinct IL-17-producing cells in mycoplasma respiratory infection with a focus on the effect of IL-17 on the outcomes of infection.

The triad: respiratory microbiome - virus - immune response in the pathophysiology of pulmonary viral infections

INTRODUCTION

The longstanding dogma that the healthy lung is sterile has been refuted by recent advances in culture-independent analyses of airway samples. The respiratory microbiome comprises all airway and lung tissue-associated microbes. These micro-organisms occur throughout the upper and lower respiratory tracts, with different populations and distinct burdens at specific sites and can be classified as pathogenic or commensal.

AREAS COVERED

The majority of studies investigating the respiratory microbiome have focused on bacteria; however, emerging evidence has revealed the composition of the lung virome, the global viral communities present in the lung tissue. In this review, we searched PubMed and used keywords such as airway microbiome. We restricted outputs to English language and did not limit by any dates. We summarize the up-to-date knowledge on how the microbiome interacts with the host immune system and influences the pathogenesis of pulmonary viral infections.

EXPERT OPINION

The relationship between colonizing microbes and the host is complex and various factors need to be considered in order to appreciate its pathophysiological consequences. Understanding these intricate mechanisms of interaction among the respiratory microbiome, viruses and the immune response may lead to the development of better therapies to treat or prevent respiratory viral infections.

Microbiomic Analysis on Low Abundant Respiratory Biomass Samples; Improved Recovery of Microbial DNA From Bronchoalveolar Lavage Fluid

In recent years the study of the commensal microbiota is driving a remarkable paradigm shift in our understanding of human physiology. However, intrinsic technical difficulties associated with investigating the Microbiomics of some body niches are hampering the development of new knowledge. This is particularly the case when investigating the functional role played by the human microbiota in modulating the physiology of key organ systems. A major hurdle in investigating specific Microbiome communities is linked to low bacterial density and susceptibility to bias caused by environmental contamination. To prevent such inaccuracies due to background processing noise, harmonized tools for Microbiomic and bioinformatics practices have been recommended globally. The fact that the impact of this undesirable variability is negatively correlated with the DNA concentration in the sample highlights the necessity to improve existing DNA isolation protocols. In this report, we developed and tested a protocol to more efficiently recover bacterial DNA from low volumes of bronchoalveolar lavage fluid obtained from infants and adults. We have compared the efficiency of the described method with that of a commercially available kit for microbiome analysis in body fluids. We show that this new methodological approach performs better in terms of extraction efficiency. As opposed to commercial kits, the DNA extracts obtained with this new protocol were clearly distinguishable from the negative extraction controls in terms of 16S copy number and Microbiome community profiles. Altogether, we described a cost-efficient protocol that can facilitate microbiome research in low-biomass human niches.

Persistent Legionnaires' Disease and Associated Antibiotic Treatment Engender a Highly Disturbed Pulmonary Microbiome Enriched in Opportunistic Microorganisms

Despite the importance of pneumonia to public health, little is known about the composition of the lung microbiome during infectious diseases, such as pneumonia, and how it evolves during antibiotic therapy. To study the possible relation of the pulmonary microbiome to the severity and outcome of this respiratory disease, we analyzed the dynamics of the pathogen and the human lung microbiome during persistent infections caused by the bacterium Legionella pneumophila and their evolution during antimicrobial treatment. We collected 10 bronchoalveolar lavage fluid samples from three patients during long-term hospitalization due to pneumonia and performed a unique longitudinal study of the interkingdom microbiome, analyzing the samples for presence of bacteria, archaea, fungi, and protozoa by high-throughput Illumina sequencing of marker genes. The lung microbiome of the patients was characterized by a strong predominance of the pathogen, a low diversity of the bacterial fraction, and an increased presence of opportunistic microorganisms. The fungal fraction was more stable than the bacterial fraction. During long-term treatment, no genomic changes or antibiotic resistance-associated mutations that could explain the persistent infection occurred, according to whole-genome sequencing analyses of the pathogen. After antibiotic treatment, the microbiome did not recover rapidly but was mainly constituted of antibiotic-resistant species and enriched in bacteria, archaea, fungi, or protozoa associated with pathogenicity. The lung microbiome seems to contribute to nonresolving Legionella pneumonia, as it is strongly disturbed during infection and enriched in opportunistic and/or antibiotic-resistant bacteria and microorganisms, including fungi, archaea, and protozoa that are often associated with infections.IMPORTANCE The composition and dynamics of the lung microbiome during pneumonia are not known, although the lung microbiome might influence the severity and outcome of this infectious disease, similar to what was shown for the microbiome at other body sites. Here we report the findings of a comprehensive analysis of the lung microbiome composition of three patients with long-term pneumonia due to L. pneumophila and its evolution during antibiotic treatment. This work adds to our understanding of how the microbiome changes during disease and antibiotic treatment and points to microorganisms and their interactions that might be beneficial. In addition to bacteria and fungi, our analyses included archaea and eukaryotes (protozoa), showing that both are present in the pulmonary microbiota and that they might also play a role in the response to the microbiome disturbance.

Different nasopharynx and oropharynx microbiota imbalance in children with Mycoplasma pneumoniae or influenza virus infection

BACKGROUND

The Mycoplasma pneumoniae(MP) and influenza virus are two common pathogens causing pediatric acute respiratory tract infection. Though emerging reports demonstrated imbalanced respiratory microbiota in respiratory infection, the respiratory microbiota differences between MP and influenza virus remained to be explored.

METHODS

We collected paired nasopharyngeal(NP) and oropharyngeal(OP) microbial samples from 165 children, including 40 patients with MP pneumonia, 66 patients with influenza virus infection and 59 age-matched healthy children.

RESULTS

The NP and OP microbial diversity decreased in MP infection and increased in influenza infection as compared to healthy children. The Staphylococcus dominated Mycoplasma pneumoniae pneumonia(MPP) patients' NP microbiota while five representative patterns remained in influenza patients. In OP microbiota, Streptococcus significantly enriched in MPP group and decreased in Influenza group. Decision tree analysis indicated that Ralstonia and Acidobacteria could discriminate microbial samples in healthy (59/67), MP (35/38) and Influenza groups (55/60) with high accuracy.

CONCLUSIONS

This study revealed that dominant bacterial structure in the airway was niche- and disease-specific. It could facilitate the stratification of respiratory microbial samples with different infectious agents.