Chlamydophila pneumoniae and Mycoplasma pneumoniae: a role in asthma pathogenesis?

Exploring the pathogenicity of Mycoplasma pneumoniae: Focus on community-acquired respiratory distress syndrome toxins

Community-Acquired Respiratory Distress Syndrome Toxin (CARDS TX) is a unique exotoxin produced by Mycoplasma pneumoniae (MP) and has been confirmed to possess ADP-ribosyltransferase (ART) and vacuolating activities. CARDS TX binds to receptors on the surfaces of mammalian cells followed by entry into the cells through clathrin-mediated endocytosis, and exerts cytotoxic effects by undergoing retrograde transport and finally cleavage on endosomes and cellular organelles. In addition, CARDS TX can trigger severe inflammatory reactions resulting in airway dysfunction, producing allergic inflammation and asthma-like conditions. As a newly discovered virulence factor of MP, CARDS TX has been extensively studied in recent years. As resistance to macrolide drugs has increased significantly in recent years and there is no vaccine against MP, the development of a vaccine targeting CARDS TX is considered a potential preventive measure. This review focuses on recent studies and insights into this toxin, providing directions for a better understanding of MP pathogenesis and treatment. IMPORTANCE: A serious hazard to worldwide public health in recent years, Mycoplasma pneumoniae (MP) is a prominent bacterium that causes community-acquired pneumonia (CAP) in hospitalized children. Due to their high prevalence and fatality rates, MP infections often cause both respiratory illnesses and extensive extrapulmonary symptoms. It has recently been shown that MP produces a distinct exotoxin known as Community-Acquired Respiratory Distress Syndrome Toxin (CARDS TX). Mycoplasma pneumoniae pneumonia (MPP)-like tissue injury is caused by this toxin because it has both ADP-ribosyltransferase and vacuolating properties. A better knowledge of MP etiology and therapy is provided by this review, which focuses on latest research and insights into this toxin.

Prevalence and clinical relevance of comorbid pertussis infection in adult patients with asthma: A prospective, cross-sectional study

BACKGROUND

Viral or atypical bacterial respiratory infections are involved in the new development and the pathogenesis of asthma. Though an association between pertussis and asthma has been expected, few studies have reported it consistently. We assessed the prevalence and clinical relevance of pertussis infection in adult patients with asthma.

METHODS

In this prospective, cross-sectional study, newly referred, adult patients with asthma (n = 107) and with non-asthmatic subacute/chronic cough (n = 31) were enrolled. The prevalence of pertussis in patients with asthma and in those with non-asthmatic subacute/chronic cough was assessed. Next, the prevalence of newly diagnosed asthma was compared between asthmatic patients with and without pertussis. Finally, demographic characteristics of patients, blood test results, pulmonary function test results, and questionnaire scores were compared between the two patient groups.

RESULTS

The prevalence of pertussis infection was significantly higher in patients with asthma than in those with non-asthmatic subacute/chronic cough (36% vs 10%; P = 0.004). The prevalence of newly diagnosed asthma was significantly higher in asthmatic patients with pertussis than in those without (74.4% vs 50.0%; P = 0.014). The physical, psychological, and total scores of the Leicester Cough Questionnaire were significantly lower in asthmatic patients with pertussis than in those without (all P < 0.05). The acid-reflux, dyspeptic, and total scores of the Frequency Scale for Symptoms of Gastroesophageal Reflux Disease (GERD) (FSSG) were significantly higher in asthmatic patients with pertussis than in those without (all P ≤ 0.05). The FSSG acid-reflux score was negatively correlated with the cough-specific quality of life (QOL) score only in asthmatic patients with pertussis (rho = -0.68, P = 0.01).

CONCLUSIONS

The prevalence of pertussis infection was significantly higher in adult patients with asthma than in those with non-asthmatic subacute/chronic cough. In patients with asthma, comorbid pertussis infection may play a role in newly diagnosed asthma and may contribute to impaired cough-specific QOL partly due to worsening acid-reflux symptoms of GERD.

Investigating the occurrence of autoimmune diseases among children and adolescents hospitalized for Mycoplasma pneumoniae infections

Background

Mycoplasma pneumoniae infection is common in the general population and may be followed by immune dysfunction, but links with subsequent autoimmune disease remain inconclusive.

Objective

To estimate the association of M. pneumoniae infection with the risk of subsequent autoimmune disease.

Methods

This retrospective cohort study examined the medical records of South Korean children from 01/01/2002 to 31/12/2017. The exposed cohort was identified as patients hospitalized for M. pneumoniae infection. Each exposed patient was matched with unexposed controls based on birth year and sex at a 1:10 ratio using incidence density sampling calculations. The outcome was subsequent diagnosis of autoimmune disease, and hazard ratios (HRs) were estimated with control for confounders. Further estimation was performed using hospital-based databases which were converted to a common data model (CDM) to allow comparisons of the different databases.

Results

The exposed cohort consisted of 49,937 children and the matched unexposed of 499,370 children. The median age at diagnosis of M. pneumoniae infection was 4 years (interquartile range, 2.5-6.5 years). During a mean follow-up time of 9.0 ± 3.8 years, the incidence rate of autoimmune diseases was 66.5 per 10,000 person-years (95% CI: 64.3-68.8) in the exposed cohort and 52.3 per 10,000 person-years (95% CI: 51.7-52.9) in the unexposed cohort, corresponding to an absolute rate of difference of 14.3 per 10,000 person-years (95% CI: 11.9-16.6). Children in the exposed cohort had an increased risk of autoimmune disease (HR: 1.26; 95% CI: 1.21-1.31), and this association was similar in the separate analysis of hospital databases (HR: 1.25; 95% CI 1.06-1.49).

Conclusion

M. pneumoniae infection requiring hospitalization may be associated with an increase in subsequent diagnoses of autoimmune diseases.

Prevalence of acute infection in adults with asthma exacerbation: A systematic review and meta-analysis

BACKGROUND

Acute respiratory infections are a major trigger of asthma exacerbations. This study sought to estimate the overall proportion of viruses, atypical pathogens, and bacteria detected in adults with asthma exacerbations.

METHODS

PubMed, EMBASE, and Cochrane Library databases and all related studies from the reviews and references were searched from inception to February 13, 2020. Two authors independently performed study selection, data extraction, as well as quality evaluation. Subsequently, meta-analysis, between-study heterogeneity, and publication bias assessment were conducted on RStudio.

RESULTS

Forty-three eligible studies comprising 3511 adults were included, of which 21 publications mentioned multiple infections during acute asthma attacks. Meta-analysis showed an acute infection prevalence of 40.19% (95% confidence interval [CI] 34.53%-45.99%). Viruses, atypical pathogens, and bacteria were detected in 38.76% (95% CI 32.02%-45.71%), 8.29% (95% CI 2.64%-16.27%), and 7.05% (95% CI 3.34%-11.81%) of asthmatics during exacerbations, respectively. Rhinovirus infections are always the dominant trigger for exacerbations with a proportion of 20.02% (95% CI 14.84%-25.73%). Substantial heterogeneity across studies (Cochran Q test: 479.43, P < 0.0001, I2 = 91.2%) was explained by subgroup analysis, indicating that year, region, population, respiratory secretion, detection method, pathogen, and study quality were all influencing factors.

CONCLUSION

This meta-analysis provided the first quantitative epidemiological data for adults, and in the future, more research and health-care supports are necessary in this area.

The role of serum inflammatory in mycoplasma pneumonia infection with respiratory asthma

OBJECTIVE

With the growing frequency of Mycoplasma pneumoniae infections linked to respiratory asthma (MP-RA), particularly in children, the quest for novel diagnostic molecular markers has become critical. We examined the link between serum immunoglobulin, inflammatory variables, vitamin A, and vitamin D levels in MP-RA patients and then found markedly diagnostic indicators.

METHODS

From January 2015 to March 2020, our hospital screened 55 cases of healthy control children (HC), 53 instances of mycoplasma pneumonia infection complicated with respiratory asthma (MP-RA), and 58 cases of non-respiratory asthma children for pneumonia mycoplasma infection (MP). Serum immunoglobulins, inflammatory markers, vitamin D, and vitamin A levels were analyzed, and a predictive model including the feature chosen in the least absolute shrinkage and selection operator regression model was developed.

RESULTS

Serum TNF- and IL-1b levels were greater in MP-RA children than in MP children, but 25(OH)D, IgG, and IgA levels were lower. Our findings verified the link between IgA, TNF-a, 25(OH)D, and vitamin A with MP-RA. In addition, TNF-a, IL-1b, 25(OH)D (Vit-D), IgG, and IgA were the predictors in the prediction nomogram, showing the combined influence of serum inflammation in MP-RA. C-index of 0.985 (95% CI: -1.25 to 1.68) shows high scaling ability and the model exhibits good discriminative capacity. With range validation, the high C-index value of 0.96 is still possible.

CONCLUSION

TNF-a, IL-1b, 25(OH)D (Vit-D), IgG, and IgA were considered as predictors in children with MP-RA was investigated in this research.

CD4⁺ T effector memory cell responses in Chlamydia pneumoniae-stimulated peripheral blood mononuclear cells in nonasthmatic subjects

Chlamydia pneumoniae (C. pneumoniae) is a gram-negative intracellular bacterium that causes respiratory infection in humans, including subjects with or without asthma. C. pneumoniae activates cells (e.g., monocytes/macrophages) in vitro, and produces cytokines that may contribute to inflammatory responses observed in asthma. Immunological differences exist between subjects with or without asthma, with regard to host responses to C. pneumoniae. The heterogeneity and subsequent diverse pathophysiology of asthma can be better understood by analyzing the repertoire of T-cell subpopulations; the most common distinction between different asthma endotypes includes cytokines produced by CD4⁺  cells (T helper (Th)2 high vs. Th2 low).

Nasopharyngeal microbial profiles associated with the risk of airway allergies in early childhood

BACKGROUND

Airway microbiota may play an important role in regulating the immune response related to allergic respiratory diseases. A molecular-based approach was used to analyze the association between nasopharyngeal microbiota, serum immunoglobin (Ig)E levels, and childhood respiratory allergies.

METHODS

Nasopharyngeal swabs were collected from children aged 36 months with three phenotypes, including allergic respiratory diseases plus atopy, atopy alone, and healthy controls for microbiome analysis using Illumina-based 16S rRNA gene sequencing.

RESULTS

In total, 87 children were enrolled, including 36 with allergic respiratory diseases plus atopy, 21 with atopy alone, and 30 healthy controls. Proteobacteria (45.7%), Firmicutes (29.3%), and Actinobacteria (15.3%) were the most prevalent phyla in the study population. Compared with healthy controls, a lower Chao1 index was found in children with allergies (P < 0.035), indicating that bacterial richness was inversely associated with airway allergies. Additionally, in comparison with healthy controls, the genera Acinetobacter, Moraxella, Asaia, and Rhodococcus were more abundant and positively correlated with total serum IgE levels in children with allergies (P < 0.01), whereas the genera Enterococcus and Rickettsia were inversely correlated with total IgE levels, and also appeared to be negatively associated with airway allergies (P < 0.01).

CONCLUSIONS

The composition of the nasopharyngeal microbiota alteration may have an influence on childhood respiratory allergies. The inverse association between bacterial richness and allergies postulated that children living in a microbially hygienic environment may increase their risk of developing respiratory allergies.

Prevalence, risk factors and outcome of Mycoplasma pneumoniae infection among children in Uganda: a prospective study

BACKGROUND

: Atypical bacteria cause 10-40% of all childhood pneumonia.. Data on the burden of atypical pneumonia in sub-Saharan Africa are limited.

AIM

: To determine the prevalence, associated factors, and outcome of Mycoplasma pneumoniae infection in children with respiratory symptoms at Mulago National Referral Hospital, Kampala.

METHODS

: Children aged 2 months to 12 years with cough and/or difficult breathing and fast breathing were recruited. A clinical history and physical examination were undertaken. Blood samples for Mycoplasma pneumoniae IgM antibodies were taken at enrolment and Day 21 and induced sputum for DNA-PCR. Admitted participants were followed for a maximum of 7 days or until discharge or death, whichever came first.

RESULTS

: A total of 385 children were enrolled, and, of these, 368 (95.6%) were <5 years. Overall, 60/385 (15.6%) participants tested positive for M. pneumoniae IgM and/or DNA-PCR. Of these, 56/60 (93.3%) were <5 years of age. Wheezing was present in 21/60 (35.0%) of the children with atypical pneumonia and in 128/325 (39.4%) with typical pneumonia. The factors associated with M. pneumonia were female sex (AOR 1.94, 95% CI 1.22-3.08, p < 0.001), age ≥12 months (AOR 2.73, 95% CI 1.53-4.87, p = 0.01) and a history of prematurity (AOR 2.07, 95% CI 1.23-3.49, p = 0.01). Mortality was 17/352 (4.8%) and, of these, 4/17 (23.5%) had M. pneumonia.

CONCLUSION

: M. pneumonia is common in young children , especially females above 2 years and those with history of prematurity. It presents with severe symptoms. The results of the study highlight the importance of considering atypical bacteria in under-5s with the symptoms of pneumonia.

Chlamydia pneumoniae-Induced IFN-Gamma Responses in Peripheral Blood Mononuclear Cells Increase Numbers of CD4+ but Not CD8+ T Effector Memory Cells

Background

Chlamydia pneumoniae causes respiratory infection in adults and children. Previous studies in our laboratory identified significantly higher in vitro T lymphocyte responses to C. pneumoniae in children with asthma compared to healthy controls which may indicate the presence of T effector memory (TEM) lymphocytes.

Aim

In the present study, healthy subjects were screened for the presence of TEM cells and their cytokines. CCR7 negative effector TEMs may indicate persistent infection with C. pneumoniae.

Methods

Peripheral blood mononuclear cells (PBMC) (1×10⁶/mL) from adult non-asthmatic subjects were infected for 1h ± C. pneumoniae TW-183 at a multiplicity of infection (MOI) = 0.1 and cultured (48 hrs). Distributions of lymphocytes (CD4+, CD8+) and TEM cells (CD4+CCR7+CD45RA+CD154+, CD8+CCR7+CD45RA+CD154+) were determined. Levels of intracellular interleukin (IL)-2, IL-4, and interferon (IFN)-gamma were measured (flow microfluorimetry); IFN-gamma was measured in supernatants (ELISA).

Results

C. pneumoniae infection led to a decrease in numbers of CD8+ TEM and CD8+CD154+ cells; CD4+TEM and CD4+CD154+ cells did not change. Numbers of TEM cells (CD4+IL-2+, CD8+ IL-2+) also decreased. However, number of TEM cells (CD4+IL4-+, CD8+ IL-4+) and (CD4+ IFN-gamma+, CD8+IFN-gamma+) did not change. When stratified according to IFN-gamma+ status, numbers of CD4+ IL-2+ and CD4+IL-4+ TEMs increased; CD8+IL-2+ and CD8+ IL-4+ TEMs decreased.

Conclusion

C. pneumoniae-induced PBMC IFN-gamma+ responses increased numbers of CD4+ IL-2+ and CD4+IL-4+ TEM cells, while CD8+IL-2+ and CD8+IL-4+ TEMs decreased. Production of IFN-gamma by C. pneumoniae infected PBMC should be further studied as a biomarker of persistent infection in humans.

Chlamydia pneumoniae and chronic asthma: Updated systematic review and meta-analysis of population attributable risk

Background

Chlamydia pneumoniae (Cp) is an obligate intracellular human respiratory pathogen producing persisting lung infection with a plausible link to asthma pathogenesis. The population attributable risk of potentially treatable Cp infection in asthma has not been reported.

Methods

The author searched from 2000 to 2020 inclusive for previously un-reviewed and new cross sectional and prospective controlled studies of Cp biomarkers and chronic asthma in both children and adults. Qualitative descriptive results and quantitative estimates of population attributable risk for selected biomarkers (specific IgG, IgA and IgE) are presented.

Findings

No large, long-term prospective population-based studies of Cp infection and asthma were identified. About half of case-control studies reported one or more significant associations of Cp biomarkers and chronic asthma. Heterogeneity of results by age group (pediatric v adult asthma), severity category (severe/uncontrolled, moderate/partly controlled, mild/controlled) and antibody isotype (specific IgG, IgA, IgE) were suggested by the qualitative results and confirmed by meta-analyses. The population attributable risks for Cp-specific IgG and IgA were nul in children and were 6% (95% confidence interval 2%-10%, p = 0.002) and 13% (9%-18%, p<0.00001) respectively in adults. In contrast to the nul or small population attributable risks for Cp-specific IgG and IgA, the population attributable risk for C. pneumoniae-specific IgE (children and adults combined) was 47% (39%-55%, p<0.00001). In the subset of studies that reported on asthma severity categories, Cp biomarkers were positively and significantly (P<0.00001) associated with asthma severity.

Interpretation

C. pneumoniae-specific IgE is strongly associated with asthma and asthma severity, suggesting a possible mechanism linking chronic Cp infection with asthma in a subset of individuals with asthma. Infection biomarkers should be included in future macrolide treatment trials for severe and uncontrolled asthma.

Chronic infection with Chlamydia pneumoniae in asthma: a type-2 low infection related phenotype

Background

Chlamydia pneumoniae and Mycoplasma pneumoniae have been implicated in the pathogenesis of asthma and are responsible for chronic inflammation when host immune system fails to eradicate the bacteria.

Method

We performed a prospective study on 410 patients who underwent a visit at the asthma clinic of CHU of Liege between June 2016 and June 2018 with serology testing for C. pneumoniae and M. pneumoniae.

Results

65% of our asthmatic population had serum IgA and/or IgG towards C. pneumoniae, while only 12.6% had IgM and/or IgG against M. pneumoniae. Compared to seronegative asthmatics, asthmatics with IgA+ and IgG+ against C. pneumoniae were more often male and older with a higher proportion of patients with smoking history. They received higher doses of inhaled corticosteroids (ICS) and displayed lower FEV₁/FVC ratio, higher RV/TLC ratio and lower conductance. They had higher levels of fibrinogen, though in the normal range and had lower sputum eosinophil counts. Patients with IgA− and IgG+ against C. pneumoniae were older and had higher blood monocyte counts and alpha-1-antitrypsin levels as compared to seronegative patients. Patients with IgM and/or IgG towards M. pneumoniae were more often males than seronegative asthmatics. In a subpopulation of 14 neutrophilic asthmatics with Chlamydia pneumoniae IgA + /IgG + treated with macrolides, we found a significant decrease in blood neutrophils and normalization of sputum neutrophil count but no effect on asthma quality of life and exacerbations.

Conclusion

Positive Chlamydia serologic test is more common than positive Mycoplasma serology. Asthmatics with IgA and IgG against C. pneumoniae have more severe disease with increased airway obstruction, higher doses of ICS, more signs of air trapping and less type-2 inflammation.

Study of the Etiology of Acute Respiratory Infections in Children Under 5 Years at the Dr. Agostinho Neto Hospital, Praia, Santiago Island, Cabo Verde

Background: Acute respiratory infections are one of the major causes of morbidity and mortality in children under 5 years in developing countries and are a challenge for the health system of these countries. In Cabo Verde, despite the lack of recent studies, data indicate that it affects thousands of children, being the fourth leading cause of infant mortality in 2013. The aim of this study was to identify and describe the etiological agents associated with acute respiratory tract infections in children under 5 years old, and their associated risk factors, such as clinical symptoms or socio-demographic characteristics. Methods: Naso-pharyngeal samples were collected from children under 5 years attending at Dr. Agostinho Neto Hospital (Praia, Santiago Island, Cabo Verde) with suspected ARI at different time-points during 2019. Samples were analyzed using FilmArray® Respiratory Panel v. 2.0 Plus to identify etiological agents of ARI. A questionnaire with socio-demographic information was also collected for each participant. Data analyses were carried out using the IBM SPSS version 25 (IBM Corporation, Armonk, NY) and R 3.5.1 statistical software. Results: A total of 129 naso-pharyngeal samples were included in the study. Seventeen different etiologic agents of respiratory infections were identified. HRV/EV was the most frequent agent detected, followed by FluA H3 and RSV. Coinfection with two or more pathogens was detected in up to 20% of positive samples. The results were analyzed in terms of age-group, sex, period of the year and other social and demographic factors. Conclusion: Viruses are the main causative agents of ARI in children <5 years attending at the pediatrics service at the Dr. Agostinho Neto Hospital in Praia city, Santiago Island, Cabo Verde. Some factors are described in this study as statistically associated with the presence of an infectious agent, such as having one or more children sharing the bedroom with an adult and the presence of some clinical symptoms. The data addresses the need for studies on respiratory tract infections in Cabo Verde.

Frequency of Mycoplasma pneumoniae, Legionella pneumophila and Chlamydia spp. among patients with atypical pneumonia in Tehran

Mycoplasma pneumoniae, Legionella pneumophila and Chlamydia pneumoniae are the most common bacterial agents, which account for 15-40%, 2-15% and 5-10% of atypical community-acquired pneumonia (CAP) respectively. These agents are mostly associated with infection in the outpatient setting. The aim of this study was to evaluate the frequency of these pathogens among patients with CAP attending outpatient clinics in Tehran. A cross-sectional study was carried out of 150 patients attending to educational hospitals in Tehran with CAP. M. pneumoniae, L. pneumophila and Chlamydia spp. were detected by PCR assay, targeting the P1 adhesion gene, macrophage infectivity potentiator (mip) gene and 16S rRNA gene respectively from throat swabs obtained from each patient. A total of 86 (57.3%) of 150 patients were women; median age was 50 years (interquartile range, 35-65 years). M. pneumoniae, L. pneumophila and Chlamydia spp. were detected in 37 (24.7%), 25 (16.7%) and 11 (7.3%) patients respectively; of these, 66 patients (44%) were infected at least by one of these three pathogens. The frequency of L. pneumophila was significantly higher among patients over 60 years old (p 0.03). Coinfection was detected in seven patients (4.7%); six were infected by M. pneumoniae and L. pneumophila, and only one was infected by L. pneumophila and Chlamydia spp. M. pneumoniae was the most prevalent agent of atypical CAP, and L. pneumophila was more likely to infect elderly rather than younger people. Further studies on the prevalence of CAP and its aetiologic agents are needed to improve the diagnosis and treatment of CAP patients.

Towards a personalised treatment approach for asthma attacks

Asthma attacks (exacerbations) are common, accounting for over 90 000 UK hospital admissions per annum. They kill nearly 1500 people per year in the UK, have significant associated direct and indirect costs and lead to accelerated and permanent loss of lung function. The recognition of asthma as a heterogeneous condition with multiple phenotypes has revolutionised the approach to the long-term management of the condition, with greater emphasis on personalised treatment and the introduction of the treatable traits concept. In contrast asthma attacks are poorly defined and understood and our treatment approach consists of bronchodilators and systemic corticosteroids. This review aims to explore the current limitations in the description, assessment and management of asthma attacks. We will outline the risk factors for attacks, strategies to modify this risk and describe the recognised characteristics of attacks as a first step towards the development of an approach for phenotyping and personalising the treatment of these critically important events. By doing this, we hope to gradually improve asthma attack treatment and reduce the adverse effects associated with recurrent courses of corticosteroids.

Mechanism of azithromycin in airway diseases

Azithromycin (AZM) has been used to treat chronic inflammatory airway diseases because it regulates cell–cell contact between airway epithelial cells. Airway mucus hypersecretion is an important component of chronic respiratory diseases. Mucin 5AC (MUC5AC) is the major mucin produced by airway epithelial cells, and hypersecretion of MUC5AC is a sign of various pulmonary inflammatory diseases. Recently, it was found that matrix metallopeptidase 9 is involved in mucus hypersecretion. Moreover, AZM can inhibit the ability of TNF-α-to induce interleukin (IL)-8 production. This review focuses on the effects on AZM that may be beneficial in inhibiting MUC5AC, matrix metalloprotease-9 and IL-8 production in airway epithelial cells. In addition, recent studies have begun to assess activation of mitogen-activated protein kinase (MAPK) signaling pathways in response to AZM. Understanding these new developments may be helpful for clinicians.

Azithromycin decreases Chlamydia pneumoniae-mediated Interleukin-4 responses but not Immunoglobulin E responses

BACKGROUND

Chlamydia pneumoniae is an obligate intracellular bacterium that causes respiratory infection. There may exist an association between C. pneumoniae, asthma, and production of immunoglobulin (Ig) E responses in vitro. Interleukin (IL-4) is required for IgE production.

OBJECTIVE

We previously demonstrated that doxycycline suppresses C. pneumoniae-induced production of IgE and IL-4 responses in peripheral blood mononuclear cells (PBMC) from asthmatic subjects. Whereas macrolides have anti-chlamydial activity, their effect on in vitro anti-inflammatory (IgE) and IL-4 responses to C. pneumoniae have not been studied.

METHODS

PBMC from IgE- adult atopic subjects (N = 5) were infected +/- C. pneumoniae BAL69, +/- azithromycin (0.1, 1.0 ug/mL) for 10 days. IL-4 and IgE levels were determined in supernatants by ELISA. IL-4 and IgE were detected in supernatants of PBMC (day 10).

RESULTS

When azithromycin (0.1, 1.0 ug/ml) was added, IL-4 levels decreased. At low dose, IgE levels increased and at high dose, IgE levels decreased. When PBMC were infected with C. pneumoniae, both IL-4 and IgE levels decreased. Addition of azithromycin (0.1, 1.0 ug/mL) decreased IL-4 levels and had no effect on IgE levels.

CONCLUSIONS

These findings indicate that azithromycin decreases IL-4 responses but has a bimodal effect on IgE responses in PBMC from atopic patients in vitro.

Diagnostic utility of serology and polymerase chain reaction for detection of Mycoplasma pneumoniae and Chlamydophila pneumoniae in paediatric community-acquired lower respiratory tract infections

Purpose

Mycoplasma pneumoniae (M. pneumoniae) and Chlamydophila pneumoniae (C. pneumoniae) play a significant role in children of all ages with lower respiratory tract infections (LRTIs). This study was conducted to detect M. pneumoniae and C. pneumoniae in children with community-acquired LRTIs employing serology, polymerase chain reaction (PCR) and nested PCR analysis.

Material and Methods

This study included 75 children with acute LRTIs for detection of M. pneumoniae and C. pneumoniae. Blood was obtained for M. pneumoniae and C. pneumoniae antibodies and nasopharyngeal aspirates for M. pneumoniae PCR and C. pneumoniae nested PCR.

Results

M. pneumoniae infection was positive in 9 (64.21%) children aged 2-6 months and in 5 (35.79%) aged 7 months-12 years, and this difference was statistically significant (P = 0.002). C. pneumoniae infection was comparable within the age group and statistically insignificant (P = 0.43). Clinical and radiological profiles of M. pneumoniae- and C. pneumoniae-positive and negative patients were numerically comparable. Serology and PCR together detected M. pneumoniae infection in 14 (18.6%) children. The sensitivity, specificity and positive and negative predictive values of serology were 77.78%, 92.42%, 58.33% and 96.83%, respectively. C. pneumoniae infection was positive in 11 (14.6%) children by serology and nested PCR with 50% sensitivity, 87.67% specificity, 10% positive predictive value and 98.46% negative predictive value.

Conclusions

Our study confirms that M. pneumoniae and C. pneumoniae play a significant role in community-acquired LRTIs and a combination of serology and nested PCR is useful for its diagnosis.

Chlamydia pneumoniae immunoglobulin E antibody levels in patients with asthma compared with non-asthma

Chlamydia pneumoniae is an obligate intracellular bacterium that causes respiratory infection in adults and children. There is evidence for an association between atypical bacterial pathogens and asthma pathogenesis. We sought to determine whether past C. pneumoniae infection triggers C. pneumoniae- IgE antibodies (Abs) in asthmatics and non-asthmatics, who had detectable IgG titers. C. pneumoniae IgE Abs were quantified using enzyme immunoassay (EIA). C. pneumoniae IgE Ab levels were higher in asthmatics compared with non-asthmatics. There was no correlation found between total serum IgE levels and specific C. pneumoniae IgE Ab levels. C. pneumoniae infection may trigger IgE-specific responses in asthmatics.

Is Ascaris lumbricoides a risk factor for development of asthma? A systematic review and meta-analysis

There are numerous epidemiological and experimental evidences to suggest that Ascaris lumbricoides infection is a neglected risk factor for development of asthma. For this purpose, we conducted a systematic review and meta-analysis for better understanding of this relationship. Systematic searching (PubMed, Scopus, Web of Science and Google Scholar) was done, up to September 30, 2019 to identify the relevant studies. We applied random-effects meta-analysis model to generate the overall odds ratio (OR) and 95% confidence intervals (CIs). Heterogeneity was assessed with I2 and τ2 statistic. Finally, 19 studies (totally 25 datasets), including 14 datasets with microscopic methods (1830 asthmatic patients (APs) and 3802 healthy controls (HCs)) and 11 datasets with serological methods (1543 APs and 3507 HCs) met the eligibility criteria. Considering to the serological methods, our results demonstrated that the APs had higher seroprevalence rate of A. lumbricoides (48.3% vs. 35.1%) than HCs, showing a significant association (pooled crude OR, 1.53; 95%CI, 1.07-2.18). Moreover, microscopic methods showed a higher prevalence of A. lumbricoides infection in the APs compared to the HCs (37.2% vs. 30.2%), but no significant association was found between APs and HCs (pooled crude OR, 1.19; 95%CI, 0.92-1.55). After adjustment for confounders, results showed no significant association for both serological (pooled adjusted OR, 1.43; 95%CI, 0.93-2.19) and microscopic (pooled adjusted OR, 1.05; 95%CI, 0.78-1.42) methods. Despite heterogeneous results, accurate and better quality studies are needed to determine the effect of A. lumbricoides infection on induction or exacerbation of asthma.

Chronic Inflammatory Diseases at Secondary Sites Ensuing Urogenital or Pulmonary Chlamydia Infections

Chlamydia trachomatis and C. pneumoniae are members of the Chlamydiaceae family of obligate intracellular bacteria. The former causes diseases predominantly at the mucosal epithelial layer of the urogenital or eye, leading to pelvic inflammatory diseases or blindness; while the latter is a major causative agent for pulmonary infection. On top of these well-described diseases at the respective primary infection sites, Chlamydia are notoriously known to migrate and cause pathologies at remote sites of a host. One such example is the sexually acquired reactive arthritis that often occurs at few weeks after genital C. trachomatis infection. C. pneumoniae, on the other hand, has been implicated in an extensive list of chronic inflammatory diseases which include atherosclerosis, multiple sclerosis, Alzheimer’s disease, asthma, and primary biliary cirrhosis. This review summarizes the Chlamydia infection associated diseases at the secondary sites of infection, and describes the potential mechanisms involved in the disease migration and pathogenesis.

Zinc and iron complexes of oleanolic acid, (OA) attenuate allergic airway inflammation in rats

Oleanolic acid (OA) is a hydroxyl pentacyclic triterpene acid (HTAs) used in various ailments. Inflammatory diseases may be profoundly influenced by iron (Fe) and zinc (Zn) status. We studied the anti-asthmatic effects of two metal complexes (Fe and Zn) of OA in the ovalbumin (OVA)-induced rat model. Delayed type hypersensitivity (DTH) was measured. Total and differential leucocyte count was done in blood as well as bronchoalveolar lavage fluid (BALF). The mRNA expression levels of pro-inflammatory cytokines were measured in lung tissue by reverse transcription polymerase chain reaction. The levels of cyclooxygenase-2 (COX-2), immunoglobulin E (IgE) and 5-lipoxygenase (5-LOX) were estimated by enzyme linked immunosorbent assay. Splenocyte proliferation was performed through BrdU uptake method and nitric oxide levels were measured by colorimetric assay kit. The acute toxicity study was also done for the complexes. The asthmatic group developed allergic airway inflammation shown by increased DTH and inflammatory markers in blood and BALF. OA + Fe and OA + Zn displayed significant decrease in DTH, NO, expression of IL-4, 5, 13, 17, toll-like receptor-2, nuclear factor-kappa B and tumor necrosis factor-α; serum IgE, COX-2, and 5-LOX. The metal complexes also attenuated OVA-stimulated splenocyte proliferation. While no hepatotoxic or nephrotoxic potential was shown by OA + Fe and OA + Zn. Our findings indicate that both OA + Fe and OA + Zn possess significant anti-asthmatic effect which may be ascribed to its immunomodulatory and anti-inflammatory features.

The crosstalk between microbiome and asthma: Exploring associations and challenges

With the advancement of high‐throughput DNA/RNA sequencing and computational analysis techniques, commensal bacteria are now considered almost as important as pathological ones. Understanding the interaction between these bacterial microbiota, host and asthma is crucial to reveal their role in asthma pathophysiology. Several airway and/or gut microbiome studies have shown associations between certain bacterial taxa and asthma. However, challenges remain before gained knowledge from these studies can be implemented into clinical practice, such as inconsistency between studies in choosing sampling compartments and/or sequencing approaches, variability of results in asthma studies, and not taking into account medication intake and diet composition especially when investigating gut microbiome. Overcoming those challenges will help to better understand the complex asthma disease process. The therapeutic potential of using pro‐ and prebiotics to prevent or reduce risk of asthma exacerbations requires further investigation. This review will focus on methodological issues regarding setting up a microbiome study, recent developments in asthma bacterial microbiome studies, challenges and future therapeutic potential.

Nonallergic Triggers and Comorbidities in Asthma Exacerbations and Disease Severity

Asthma triggers are exogenous or endogenous factors that could worsen asthma acutely to cause an exacerbation, or perpetuate chronic symptoms and airflow limitation. Because it is well known that recent asthma exacerbations and poor symptom control are strong predictors of future disease activity, it is not surprising that the number of (allergic or nonallergic) asthma triggers in the environment correlates with the disease-related quality of life. There is a need to identify and avoid specific triggers as the centerpiece of disease management, especially in those with heightened sensitivity to certain factors.

Chlamydia pneumoniae-induced tumour necrosis factor alpha responses are lower in children with asthma compared with non-asthma

Introduction

Chlamydia pneumoniae respiratory tract infection has been implicated in the pathogenesis of reactive airway disease and asthma. Innate cytokine responses that are protective of infection with intracellular pathogens may be impaired in patients with asthma. Tumour necrosis factor alpha (TNF-α) is a cytokine related to functions of monocytes and may inhibit C. pneumoniae infection. We investigated TNF-α responses in C. pneumoniae-infected peripheral blood mononuclear cells (PBMCs) in patients with asthma and non-asthma, and whether ciprofloxacin, azithromycin or doxycycline affects TNF-α responses.

Methods

PBMC (1.5×10⁶) from paediatric patients with asthma (n=19) and non-asthmatic controls (n=6) were infected or mock infected for 1 hour with or without C. pneumoniae AR-39 at a multiplicity of infection=0.1, and cultured+ciprofloxacin, azithromycin or doxycycline (0.1 ug/mL) for 48 hours. TNF-α levels were measured in supernatants by ELISA.

Results

When PBMC from patients with asthma were infected with C. pneumoniae, levels of TNF-α were significantly lower than in subjects without asthma (48 hours) (5.5±5.6, 38.4±53.7; p=0.0113). However, baseline responses (no infection with C. pneumoniae) were similar in asthma and non-asthma (1.0±1.7, 1.1±1.2; p=0.89). When PBMC frompatiens with asthma were infected with C. pneumoniae+ciprofloxacin, azithromycin or doxycycline, TNF-α levels increased (25%–45%); this affect was not observed in PBMC from patients without asthma.

Conclusions

We identified differences in the quantity of TNF-α produced by C. pneumoniae-infected PBMC in asthma compared with non-asthma.

Doxycycline suppresses Chlamydia pneumoniae induced interferon-gamma responses in peripheral blood mononuclear cells in children with allergic asthma

Persistent respiratory infections caused by Chlamydia pneumoniae have been implicated in the pathogenesis of chronic diseases (e.g. asthma). Antibiotics are used to treat C. pneumoniae respiratory infections; however, the use of antibiotics as anti-inflammatory agents in treatment of asthma remains controversial. The current study investigated whether ciprofloxacin, azithromycin, or doxycycline can suppress C. pneumoniae-induced production of immunoglobulin (Ig) E or cytokines in peripheral blood mononuclear cells (PBMC) obtained from asthmatic children. Apart from blood, nasopharyngeal swab specimens were also collected to test for the presence of C. pneumoniae and/or M. pneumoniae (qPCR). PBMC (1.5 x 10⁶) from asthmatic pediatric patients (N = 18) were infected or mock infected for 1 h ± C. pneumoniae AR-39 at a multiplicity of infection (MOI) = 0.1, and cultured ± ciprofloxacin, azithromycin, or doxycycline (0.1 or 1.0 μg/mLmL) for either 48 h (cytokines) or 10 days (IgE). Interleukin (IL)-4, interferon (IFN)-γ and IgE levels in supernatants were measured (ELISA). When PBMC were infected with C. pneumoniae, IL-4 and IFNγ production increased (p = 0.06 and 0.03, respectively); IgE levels were low. The now-elevated levels of IL-4 didn't decrease significantly after addition of ciprofloxacin, azithromycin, or doxycycline. However, infected PBMC IFNγ formation decreased significantly when 0.1 μg/mL doxycycline was employed (p = 0.04); no dose of ciprofloxacin or azithromycin had any impact. This inhibitory outcome with doxycycline lends support to the use of tetracyclines as immune modulators and anti-inflammatory medications in treatment of C. pneumoniae-infected asthma patients.

Mycoplasma pneumoniae induces allergy by producing P1-specific immunoglobulin E

BACKGROUND

Our previous study found that most Mycoplasma pneumoniae (MP) pneumonia (MPP)patients had elevated serum total immunoglobulin E (IgE) levels.

OBJECTIVE

To determine components of MP that can cause an IgE increase in children, and to clarify its specific mechanism.

METHODS

The components of MP cells were isolated by serum IgE from patients with MP pneumonia. These components obtained through the prokaryotic expression were used as allergens to detect the proportion of allergen-specific IgE produced in MPP patients, and the clinical characteristics and related immune parameters of these patients who produced this allergen-specific IgE were also analyzed. In addition, a cell experiment was used to verify the biological effect of these components in vitro.

RESULTS

P1-specific IgE was detected in serum of MPP children. An approximately 24-kDa polypeptide of P1 protein was obtained through prokaryotic expression purified by nickel agarose affinity chromatography. Approximately 9.2% of MPP patients produced IgE against this polypeptide of P1 protein, which was more likely to be produced in MPP patients with no history of allergies or family history of allergy-related diseases. P1-specific IgE-positive MPP patients had more severe clinical symptoms, with excessive secretion of interleukin (IL)-4 and IL-5 and overdifferentiation of Th0 cells into Th2 cells. Tests also demonstrated that the P1 protein stimulated excessive secretion of IL-4 and IL-5 in peripheral blood mononuclear cells from the peripheral blood of healthy donors.

CONCLUSION

Mycoplasma pneumoniae is not only an infectious agent but also an allergen for certain individuals. The P1 protein of MP can induce the production of P1-specific IgE.

Chlamydia pneumoniae Induces Interferon Gamma Responses in Peripheral Blood Mononuclear Cells in Children with Allergic Asthma

Respiratory infections caused by Chlamydia pneumoniae have been associated with exacerbations of asthma. Cell-mediated immunity (CMI) is critical for maintaining immunity. We compared interferon (IFN)-γ responses in C. pneumoniae-infected peripheral blood mononuclear cells (PBMC) in paediatric patients ± asthma. Presence of C. pneumoniae was tested from asthma patients (N = 17) and non-asthmatic controls (N = 16) (PCR). PBMC were infected for 1 h ± C. pneumoniae AR-39 (MOI = 0.1) and cultured for 48 h. IFN-γ levels were measured in supernatants (ELISA). C. pneumoniae-IgG antibodies in serum were determined (MIF). All subjects tested negative for C. pneumoniae (PCR). C. pneumoniae-induced IFN-γ production in vitro was more prevalent in asthma compared with non-asthma; levels of IFN-γ were higher in asthma compared with non-asthma (P = 0.003). There was no association between recent respiratory infection and positive IFN-γ responses. These data show that C. pneumoniae modulates IFN-γ responses in patients with asthma, even in absence of active infection.

Addressing unmet needs in understanding asthma mechanisms: From the European Asthma Research and Innovation Partnership (EARIP) Work Package (WP)2 collaborators

Asthma is a heterogeneous, complex disease with clinical phenotypes that incorporate persistent symptoms and acute exacerbations. It affects many millions of Europeans throughout their education and working lives and puts a heavy cost on European productivity. There is a wide spectrum of disease severity and control. Therapeutic advances have been slow despite greater understanding of basic mechanisms and the lack of satisfactory preventative and disease modifying management for asthma constitutes a significant unmet clinical need. Preventing, treating and ultimately curing asthma requires co-ordinated research and innovation across Europe. The European Asthma Research and Innovation Partnership (EARIP) is an FP7-funded programme which has taken a co-ordinated and integrated approach to analysing the future of asthma research and development. This report aims to identify the mechanistic areas in which investment is required to bring about significant improvements in asthma outcomes.

Mycoplasma pneumoniae CARDS toxin elicits a functional IgE response in Balb/c mice

Mycoplasma pneumoniae is strongly associated with new onset asthma and asthma exacerbations. Until recently, the molecular mechanisms utilized by M. pneumoniae to influence asthma symptoms were unknown. However, we recently reported that an ADP-ribosylating and vacuolating toxin called the Community Acquired Respiratory Distress Syndrome toxin, CARDS toxin, produced by M. pneumoniae was sufficient to promote allergic inflammation and asthma-like disease in mice. A mouse model of CARDS toxin exposure was used to evaluate total and CARDS-toxin specific serum IgE responses. Mast cell sensitization, challenge, and degranulation studies determined functionality of the CARDS toxin-specific IgE. In the current study, we report that a single mucosal exposure to CARDS toxin was sufficient to increase total serum IgE and CARDS toxin-specific IgE in mice. Mice given a second mucosal challenge of CARDS toxin responded with significant increases in total and CARDS toxin-specific IgE. CARDS toxin-specific IgE bound to an N-terminal peptide of CARDS toxin but not the C-terminal peptide. Likewise, full-length CARDS toxin and the N-terminal peptide induced mast cell degranulation. Altogether, these data demonstrate that exposure to CARDS toxin is sufficient to generate functional IgE in mice. M. pneumoniae and CARDS toxin are strongly associated with asthma exacerbations raising the possibility that the CARDS toxin-specific IgE-mast cell axis contributes to disease pathogenesis.

Airway and serum biochemical correlates of refractory neutrophilic asthma

Background

Despite progress in the diagnosis and management of asthma, many patients have poorly controlled or refractory asthma (RA). The mechanism of this RA is not well understood.

Objective

We sought to explore the relationship between neutrophils and other biomarkers of RA.

Method

Sixty patients with RA, 30 patients with nonrefractory asthma (NRA), and 20 healthy subjects were enrolled. We performed a comprehensive characterization of these study subjects, which included laboratory and pulmonary function studies, chest computed tomography, and bronchoscopy with bronchoalveolar lavage (BAL). We analyzed BAL fluid and serum for a total of 244 biomolecules using a multiplex assay and correlated them with clinical and other laboratory parameters.

Results

RA was significantly different from NRA with regard to pulmonary function indices, bronchial basement membrane thickness, and BAL fluid neutrophil and lymphocyte counts but not eosinophil counts. BAL fluid neutrophil counts negatively and positively correlated with forced vital capacity and age, respectively. Of the 244 biomolecules studied, 52 and 14 biomolecules from BAL fluid and serum, respectively, were significantly different among the study groups. Thirteen of these 52 molecules correlated with BAL fluid neutrophil counts. BAL fluid from 40% of patients with RA was positive for a pathogenic microbe. Infection-negative neutrophilic RA was associated with an increase in levels of select biomarkers of inflammation in the serum, suggesting the presence of systemic inflammation.

Conclusions

RA was associated with increased numbers of neutrophils and proneutrophilic biomolecules in the airways. Subclinical infection was present in 40% of patients with RA, which likely contributed to neutrophilic inflammation. A subgroup of patients with noninfected neutrophilic RA was associated with systemic inflammation.

Prevalence of Atypical Pathogens in Patients With Cough and Community-Acquired Pneumonia: A Meta-Analysis

PURPOSE

Community-acquired pneumonia (CAP), acute cough, bronchitis, and lower respiratory tract infections (LRTI) are often caused by infections with viruses or Streptococcus pneumoniae. The prevalence of atypical pathogens Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, and Bordetella pertussis among patients with these illnesses in the ambulatory setting has not been previously summarized. We set out to derive prevalence information from the existing literature.

METHODS

We performed a systematic review of MEDLINE for prospective, consecutive-series studies reporting the prevalence of M pneumoniae, C pneumoniae, L pneumophila and/or B pertussis in outpatients with cough, acute bronchitis, LRTI, or CAP. Articles were independently reviewed by 2 authors for inclusion and abstraction of data; discrepancies were resolved by consensus discussion. A meta-analysis was performed on each pathogen to calculate the pooled prevalence estimates using a random effects model of raw proportions.

RESULTS

Fifty studies met our inclusion criteria. While calculated heterogeneity was high, most studies reported prevalence for each pathogen within a fairly narrow range. In patients with CAP, the overall prevalences of M pneumoniae and C pneumoniae were 10.1% (95% CI, 7.1%-13.1%) and 3.5% (95% CI, 2.2%-4.9%), respectively. Consistent with previous reports, M pneumoniae prevalence peaked in roughly 6-year intervals. Overall prevalence of L pneumophila was 2.7% (95% CI, 2.0%-3.4%), but the organism was rare in children, with only 1 case in 1,765. In patients with prolonged cough in primary care, the prevalence of B pertussis was 12.4% (95% CI, 4.9%-19.8%), although it was higher in studies that included only children (17.6%; 95% CI, 3.4%-31.8%).

CONCLUSIONS

Atypical bacterial pathogens are relatively common causes of lower respiratory diseases, including cough, bronchitis, and CAP. Where surveillance data were available, we found higher prevalences in studies where all patients are tested for these pathogens. It is likely that these conditions are underreported, underdiagnosed, and undertreated in current clinical practice.

Azithromycin for Acute Exacerbations of Asthma : The AZALEA Randomized Clinical Trial

IMPORTANCE

Guidelines recommend against antibiotic use to treat asthma attacks. A study with telithromycin reported benefit, but adverse reactions limit its use.

OBJECTIVE

To determine whether azithromycin added to standard care for asthma attacks in adults results in clinical benefit.

DESIGN, SETTING, AND PARTICIPANTS

The Azithromycin Against Placebo in Exacerbations of Asthma (AZALEA) randomized, double-blind, placebo-controlled clinical trial, a United Kingdom-based multicenter study in adults requesting emergency care for acute asthma exacerbations, ran from September 2011 to April 2014. Adults with a history of asthma for more than 6 months were recruited within 48 hours of presentation to medical care with an acute deterioration in asthma control requiring a course of oral and/or systemic corticosteroids.

INTERVENTIONS

Azithromycin 500 mg daily or matched placebo for 3 days.

MAIN OUTCOMES AND MEASURES

The primary outcome was diary card symptom score 10 days after randomization, with a hypothesized treatment effect size of -0.3. Secondary outcomes were diary card symptom score, quality-of-life questionnaires, and lung function changes, all between exacerbation and day 10, and time to a 50% reduction in symptom score.

RESULTS

Of 4582 patients screened at 31 centers, 199 of a planned 380 were randomized within 48 hours of presentation. The major reason for nonrecruitment was receipt of antibiotics (2044 [44.6%] screened patients). Median time from presentation to drug administration was 22 hours (interquartile range, 14-28 hours). Exacerbation characteristics were well balanced across treatment arms and centers. The primary outcome asthma symptom scores were mean (SD), 4.14 (1.38) at exacerbation and 2.09 (1.71) at 10 days for the azithromycin group and 4.18 (1.48) and 2.20 (1.51) for the placebo group, respectively. Using multilevel modeling, there was no significant difference in symptom scores between azithromycin and placebo at day 10 (difference, -0.166; 95% CI, -0.670 to 0.337), nor on any day between exacerbation and day 10. No significant between-group differences were observed in quality-of-life questionnaires or lung function between exacerbation and day 10, or in time to 50% reduction in symptom score.

CONCLUSIONS AND RELEVANCE

In this randomized population, azithromycin treatment resulted in no statistically or clinically significant benefit. For each patient randomized, more than 10 were excluded because they had already received antibiotics.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01444469.

Chlamydia pneumoniae, and mycoplasma pneumoniae: Are they related to severe asthma in childhood?

BACKGROUND

Mycoplasma pneumoniae and Chlamydia pneumoniae are frequent agents of acute respiratory diseases and they have been recognized as infectious triggers of asthma.

OBJECTIVE

To determine the frequency of these triggers and their relationship to severe asthma.

METHODS

82 patients were enrolled in a prospective cross-sectional study from January 2007 to March 2013 and they were divided into three study groups: Group 1: 27 children with severe asthma, Group 2: 29 children with stable asthma and Group 3: 26 children which was the control group. Serological tests included IgG and IgM for both C. pneumoniae and M. pneumoniae.

RESULTS

Average age ± SD was 10.9 ± 2.5 for Group 1; 10.1 ± 2.9 for Group 2 and 9.9± 1.9 for Group 3 (p = 0.4). M. pneumoniae IgM was observed in 6/27 (22.2%) in Group 1, 2/29 (6.9%) in Group 2 and 0/26 in the Control Group (p = 0,01). C.pneumoniae IgM was present in 7/26 (26.9%) in Group 1, 2/29 (6.9%) in Group 2 and 0/26 in Group 3 (p = 0.005). No significant difference was observed between Group 2 and Group 3. M. pneumoniae IgG was observed in 7/27 (25.9%) in Group 1, 4/29 (13.7%) in Group 2 and 0/26 in the Control Group (p < 0,05). C.pneumoniae IgG was present in 8/26 (30.7%) in Group 1, 5/29 (17.2%) in Group 2 and 0/26 in Group 3 (p < 0,05).

CONCLUSIONS

M. pneumoniae and C. pneumoniae may play a role in the development of severe asthma.

Involvement of Toll-like receptor 2 and epidermal growth factor receptor signaling in epithelial expression of airway remodeling factors

Staphylococcus aureus (SA) colonization and infection is common, and may promote allergic or inflammatory airway diseases, such as asthma, cystic fibrosis, and chronic rhinosinusitis by interacting with airway epithelial cells. Airway epithelial cells not only comprise a physical barrier, but also play key roles in immune, inflammatory, repair, and remodeling responses upon encounters with pathogens. To elucidate the impact of SA on epithelial-mediated remodeling of allergic airways, we tested the hypothesis that SA can enhance the remodeling process. Normal human bronchial epithelial (NHBE) cells were stimulated with heat-killed SA (HKSA) or transforming growth factor (TGF) α. Cell extracts were collected to measure mRNA (real-time RT-PCR) and signaling molecules (Western blot); supernatants were collected to measure protein (ELISA) after 24 hours of stimulation. Epidermal growth factor receptor (EGFR) signaling inhibition experiments were performed using a specific EGFR kinase inhibitor (AG1478) and TGF-α was blocked with an anti-TGF-α antibody. HKSA induced both mRNA and protein for TGF-α and matrix metalloproteinase (MMP) 1 from NHBE cells by a Toll-like receptor 2-dependent mechanism. Recombinant human TGF-α also induced mRNA and protein for MMP-1 from NHBE cells; anti-TGF-α antibody inhibited HKSA-induced MMP-1, suggesting that endogenous TGF-α mediates the MMP-1 induction by HKSA. HKSA-induced MMP-1 expression was suppressed when a specific EGFR kinase inhibitor was added, suggesting that EGFR signaling was mediating the HKSA-induced MMP-1 release. Exposure or colonization by SA in the airway may enhance the remodeling of tissue through a TGF-α-dependent induction of MMP-1 expression, and may thereby promote remodeling in airway diseases in which SA is implicated, such as asthma and chronic rhinosinusitis.

Chlamydia pneumoniae enhances the Th2 profile of stimulated peripheral blood mononuclear cells from asthmatic patients

Chlamydia pneumoniae is a cause of respiratory infection in adults and children. There is evidence for an association between atypical bacterial respiratory pathogens and the pathogenesis of asthma. We compared T helper (Th) responses in C. pneumoniae - infected peripheral blood mononuclear cells (PBMC) in patients with or without asthma. PBMC (1×10(6)/mL) from asthmatic patients (N=11) and non-asthmatic controls (N=12) were infected or mock-infected for 1h +/- C. pneumoniae TW-183 at a multiplicity of infection (MOI)=1 and MOI=0.1, or cultured for 24h +/- Lactobacillus rhamnosus GG (LGG). Interleukin (IL)-4, IL-10, IL-12, Interferon (IFN)-gamma and total IgE levels were measured in supernatants (ELISA). C. pneumoniae infection led to an increase (>50%) of IgE levels in PBMC from asthmatics, compared with mock-infected on day 10; IgE wasn't detected in non-asthmatics. C. pneumoniae - infected PBMC from asthmatics increased levels of IL-4 and IFN-gamma after 24h, compared with PBMC alone; levels of IL-10 and IL-12 were low. When uninfected-PBMC from asthmatics were LGG-stimulated, after 24h, IL-4 was undetectable, but IL-10, IL-12, and IFN-gamma increased, compared with PBMC alone. Thus, C. pneumoniae infection has the ability to induce allergic responses in PBMC of asthmatics, as evidenced by production of Th2 responses and IgE.

Incident asthma and Mycoplasma pneumoniae: A nationwide cohort study

BACKGROUND

Previous studies investigating the relationship between Mycoplasma pneumoniae and incident asthma in the general population have been inconclusive.

OBJECTIVE

We conducted a nationwide cohort study to clarify this relationship.

METHODS

Using the National Health Insurance Research Database of Taiwan, we identified 1591 patients with M pneumoniae infection (International Classification of Diseases, Ninth Revision, Clinical Modification code 4830) given diagnoses between 2000 and 2008. We then frequency matched 6364 patients without M pneumoniae infection from the general population according to age, sex, and index year. Cox proportional hazards regression analysis was performed to determine the adjusted hazard ratio (aHR) of the occurrence of asthma in the M pneumoniae cohort compared with that in the non-M pneumoniae cohort.

RESULTS

Regardless of comorbidities and the use of antibiotic or steroid therapies, patients with M pneumonia infection had a higher risk of incident asthma than those without it. The aHR of asthma was 3.35 (95% CI, 2.71-4.15) for the M pneumoniae cohort, with a significantly higher risk when patients were stratified by age, sex, follow-up time, and comorbidities, including allergic rhinitis, atopic dermatitis, or allergic conjunctivitis. Patients with M pneumoniae infection had a higher risk of having early-onset (age, <12 years; aHR, 2.87) and late-onset (age, ≥12 years; aHR, 3.95) asthma. The aHR was also higher within the less than 2-year follow-up in the M pneumoniae cohort (aHR, 4.41; 95% CI, 3.40-5.74) than in the cohort without the infection.

CONCLUSION

This study found that incident cases of early-onset and late-onset asthma are closely related to M pneumoniae infection, even in nonatopic patients.

Inflammation and infections in asthma

INTRODUCTION

Asthma is driven by an inflammatory response against normally harmless environmental inorganic and organic compounds in the respiratory tract. Immune responses to airborne pathogens such as viruses and bacteria may reduce the allergic responses but are also known to trigger asthma attacks and eventually lead to severe disease condition.

OBJECTIVE

To investigate the role of respiratory pathogens concerning the induction or protection against acute or chronic asthma manifestations.

METHODS

We included 131 articles for the final review according to their relevance with the subject.

RESULTS

There is apparently contradictory interaction of respiratory germs in the airways of asthmatics which may be protective on one angle but deleterious on the other.

CONCLUSION

The relationship between inflammation and remodeling and the pathogenic role of viral and bacterial infection in the airways of asthmatic patients is still highly debatable and incompletely understood.

Cultural reflexivity in health research and practice

Recent public health movements have invoked cultural change to improve health and reduce health disparities. We argue that these cultural discourses have sometimes justified and maintained health inequalities when those with power and authority designated their own social practices as legitimate and healthy while labeling the practices of marginalized groups as illegitimate or unhealthy. This "misrecognition," which creates seemingly objective knowledge without understanding historical and social conditions, sustains unequal power dynamics and obscures the fact that what is deemed legitimate and healthy can be temporally, geographically, and socially relative. We use examples from research across multiple disciplines to illustrate the potential consequences of cultural misrecognition, highlight instances in which culture was invoked in ways that overcame misrecognition, and discuss how cultural reflexivity can be used to improve health research and practice.

No direct association between asthma and the microbiome based on currently available techniques

Current uses of culture-independent tools in previous studies have shown a significant relationship between microbiota and asthma. Although these studies are relatively new, there is also evidence of the possibility of new therapeutic strategies for the treatment or prevention of asthma. This article retrospectively examines the possible association between microorganisms and asthma. Data on all patients with different types of asthma were collected from hospital charts from the Department of Internal Medicine, Saarland University Medical Center, Germany, within the study period of 2011 to 2012. The tracheal secretions of asthmatics obtained by bronchoalveolar lavage, bronchial aspirates through flexible bronchoscopy, and directly in sputum were examined microbiologically for microorganisms. Thirty-one (10.47%, 95% CI, 6.98-13.96) of a total of 296 patients were found to have asthma microorganisms in their airways. We could not establish a causal relationship between microorganisms and asthma based on the results of our study (P = 0.893). Additionally, acute respiratory infections did not affect the microbiological colonization in asthmatics' airways (P = 0.472). We were unable to find a direct association between asthma and the microbiome based on existing diagnostic techniques.

Increased frequency of dual-positive TH2/TH17 cells in bronchoalveolar lavage fluid characterizes a population of patients with severe asthma

BACKGROUND

TH2 cells can further differentiate into dual-positive TH2/TH17 cells. The presence of dual-positive TH2/TH17 cells in the airways and their effect on asthma severity are unknown.

OBJECTIVE

We sought to study dual-positive TH2/TH17 cells in bronchoalveolar lavage (BAL) fluid from asthmatic patients, examine their response to glucocorticoids, and define their relevance for disease severity.

METHODS

Bronchoscopy and lavage were performed in 52 asthmatic patients and 25 disease control subjects. TH2 and TH2/TH17 cells were analyzed by using multicolor flow cytometry and confocal immunofluorescence microscopy. Cytokines were assayed by means of ELISA.

RESULTS

Dual-positive TH2/TH17 cells were present at a higher frequency in BAL fluid from asthmatic patients compared with numbers seen in disease control subjects. High-level IL-4 production was typically accompanied by high-level IL-17 production and coexpression of GATA3 and retinoic acid receptor-related orphan receptor γt. Increased presence of TH2/TH17 cells was associated with increased IL-17 production in lavage fluid. TH2/TH17 cell counts and IL-17 production correlated with PC20 for methacholine, eosinophil counts, and FEV1. TH2/TH17 cells, unlike TH2 cells, were resistant to dexamethasone-induced cell death. They expressed higher levels of mitogen-activated protein-extracellular signal-regulated kinase kinase 1, a molecule that induces glucocorticoid resistance. On the basis of the dominance of BAL fluid TH2 or TH2/TH17 cells, we identified 3 subgroups of asthma: TH2(predominant), TH2/TH17(predominant), and TH2/TH17(low). The TH2/TH17(predominant) subgroup manifested the most severe form of asthma, whereas the TH2/TH17(low) subgroup had the mildest asthma.

CONCLUSION

Asthma is associated with a higher frequency of dual-positive TH2/TH17 cells in BAL fluid. The TH2/TH17(predominant) subgroup of asthmatic patients manifested glucocorticoid resistance in vitro. They also had the greatest airway obstruction and hyperreactivity compared with the TH2(predominant) and TH2/TH17(low) subgroups.

Microbial communities in the upper respiratory tract of patients with asthma and chronic obstructive pulmonary disease

Respiratory infections are well-known triggers of chronic respiratory diseases. Recently, culture-independent tools have indicated that lower airway microbiota may contribute to pathophysiologic processes associated with asthma and chronic obstructive pulmonary disease (COPD). However, the relationship between upper airway microbiota and chronic respiratory diseases remains unclear. This study was undertaken to define differences of microbiota in the oropharynx of asthma and COPD patients relative to those in healthy individuals. To account for the qualitative and quantitative diversity of the 16S rRNA gene in the oropharynx, the microbiomes of 18 asthma patients, 17 COPD patients, and 12 normal individuals were assessed using a high-throughput next-generation sequencing analysis. In the 259,572 total sequence reads, α and β diversity measurements and a generalized linear model revealed that the oropharynx microbiota are diverse, but no significant differences were observed between asthma and COPD patients. Pseudomonas spp. of Proteobacteria and Lactobacillus spp. of Firmicutes were highly abundant in asthma and COPD. By contrast, Streptococcus, Veillonella, Prevotella, and Neisseria of Bacteroidetes dominated in the healthy oropharynx. These findings are consistent with previous studies conducted in the lower airways and suggest that oropharyngeal airway microbiota are important for understanding the relationships between the various parts of the respiratory tract with regard to bacterial colonization and comprehensive assessment of asthma and COPD.

Pharmacotherapy for lower respiratory tract infections

INTRODUCTION

Bacterial infections play an important role as etiological agents in acute exacerbations of chronic obstructive pulmonary disease (AECOPD), and exacerbations of non-cystic fibrosis (CF) bronchiectasis. In acute bronchitis and asthma exacerbations their role is less well defined than with patients with COPD. The clinical features, causative pathogens and therapies of common acute respiratory tract infections are detailed in this review.

AREAS COVERED

This article covers medical literature published in any language from 2000 to 2014, on 'lower respiratory tract infections', identified using PubMed, MEDLINE and ClinicalTrial.gov. The search terms used were 'COPD exacerbations', 'bronchiectasis', 'macrolides' and 'inhaled antibiotics'.

EXPERT OPINION

Given that almost half of AECOPD are caused by bacteria, administration of antibacterial agents is recommended for patients with severe exacerbations or severe underlying COPD. Chronic prophylactic use of macrolides seems to be of benefit, particularly in patients with bronchiectasis and chronic mucous hypersecretion. In an effort to manage chronic airway infection non-CF bronchiectasis due to drug-resistant pathogens, aerosolized antibiotics may be of value, and the data from recent studies are examined to demonstrate the potential value of this therapy, which is often used as an adjunctive measure to systemic antimicrobial therapy.

Dendritic cells from aged subjects display enhanced inflammatory responses to Chlamydophila pneumoniae

Chlamydophila pneumoniae (CPn) is a common respiratory pathogen that causes a chronic and persistent airway infection. The elderly display an increased susceptibility and severity to this infection. However, the underlying mechanisms are not well understood. Dendritic cells (DCs) are the initiators and regulators of immune responses. Therefore, we investigated the role of DCs in the age-associated increased CPn infection in vitro in humans. Though the expression of activation markers was comparable between the two age groups, DCs from aged subjects secreted enhanced levels of proinflammatory mediators such as TNF-α and CXCL-10 in response to CPn. In contrast, the secretion of IL-10 and innate interferons, IFN-α and IFN-λ, was severely impaired in DCs from aged donors. The increased activation of DCs from aged subjects to CPn also resulted in enhanced proliferation of CD4 and CD8 T cells in a DC-T coculture. Furthermore, T cells primed with CPn-stimulated DCs from aged subjects secreted increased levels of IFN-γ and reduced levels of IL-10 compared to DCs obtained from young subjects. In summary, DCs from the elderly displayed enhanced inflammatory response to CPn which may result in airway remodeling and increase the susceptibility of the elderly to respiratory diseases such as asthma.

Mycoplasma pneumoniae CARDS toxin exacerbates ovalbumin-induced asthma-like inflammation in BALB/c mice

Mycoplasma pneumoniae causes a range of airway and extrapulmonary pathologies in humans. Clinically, M. pneumoniae is associated with acute exacerbations of human asthma and a worsening of experimentally induced asthma in mice. Recently, we demonstrated that Community Acquired Respiratory Distress Syndrome (CARDS) toxin, an ADP-ribosylating and vacuolating toxin synthesized by M. pneumoniae, is sufficient to induce an asthma-like disease in BALB/cJ mice. To test the potential of CARDS toxin to exacerbate preexisting asthma, we examined inflammatory responses to recombinant CARDS toxin in an ovalbumin (OVA) murine model of asthma. Differences in pulmonary inflammatory responses between treatment groups were analyzed by histology, cell differentials and changes in cytokine and chemokine concentrations. Additionally, assessments of airway hyperreactivity were evaluated through direct pulmonary function measurements. Analysis of histology revealed exaggerated cellular inflammation with a strong eosinophilic component in the CARDS toxin-treated group. Heightened T-helper type-2 inflammatory responses were evidenced by increased expression of IL-4, IL-13, CCL17 and CCL22 corresponding with increased airway hyperreactivity in the CARDS toxin-treated mice. These data demonstrate that CARDS toxin can be a causal factor in the worsening of experimental allergic asthma, highlighting the potential importance of CARDS toxin in the etiology and exacerbation of human asthma.