Respiratory infections and asthma

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.

Adjuvant-independent airway sensitization and infection mouse models leading to allergic asthma

Asthma is a chronic respiratory disease of global importance. Mouse models of allergic asthma have been instrumental in advancing research and novel therapeutic strategies for patients. The application of relevant allergens and physiological routes of exposure in such models has led to valuable insights into the complexities of asthma onset and development as well as key disease mechanisms. Furthermore, environmental microbial exposures and infections have been shown to play a fundamental part in asthma pathogenesis and alter disease outcome. In this review, we delve into physiological mouse models of allergic asthma and explore literature reports on most significant interplays between microbial infections and asthma development with relevance to human disease.

Genetic polymorphisms of TLR1, TLR2, TLR3 and TLR4 in patients with recurrent or severe infections

Toll-like receptors (TLRs) play an important role in innate immunity. Previous studies have shown that single nucleotide polymorphisms (SNPs) in the genes coding for these innate immune molecules can affect susceptibility to and the outcome of certain diseases. The aim of the present study was to examine the clinical relevance of well-studied TLR1-4 SNPs in individuals who are prone to infections. Four functional SNPs, TLR1 rs5743618 (1805C > A, Ser602Ile), TLR2 rs5743708 (2258G > A, Arg753Gln), TLR3 rs3775291 (1234C > T, Leu412Phe) and TLR4 rs4986790 (896A > G, Asp299Gly), were analysed in 155 patients with recurrent respiratory infections (n = 84), severe infections (n = 15) or common variable immunodeficiency (n = 56), and in 262 healthy controls, using the High Resolution Melting Analysis method. Polymorphisms of TLR2 rs5743708 (odds ratio [OR] 3.16; 95% confidence interval [CI] 1.45-6.83, p = .004, ap = .016) and TLR4 rs4986790 (OR 1.8; 95% CI 1.05-3.12, p = .028, ap = .112) were more frequent in patients with recurrent or severe infections than in controls. Interestingly, seven patients were found to carry both variant genotypes of TLR2 and TLR4, whereas none of the control group carried such genotypes (p  ≤ .0001). Moreover, TLR2 polymorphism was associated with increased risk for acute otitis media episodes (OR, 3.02; 95% CI 1.41-6.47; p = .012). This study indicates that children and adults who are more prone to recurrent or severe respiratory infections carry one or both variant types of TLR2 and TLR4 more often than control subjects. Genetic variations of TLRs help explain why some children are more susceptible to respiratory infections.

Reduced Steroid Metabolites Identify Infection-Prone Children in Two Independent Pre-Birth Cohorts

Recurrent respiratory infections are a leading cause of morbidity and mortality in early life, but there is no broadly accepted means to identify infection-prone children during this highly vulnerable period. In this study, we investigated associations between steroid metabolites and incident respiratory infections in two pre-birth cohorts to identify novel metabolomic signatures of early infection proneness. Children from the Vitamin D Antenatal Asthma Reduction Trial and the Copenhagen Prospective Studies on Asthma in Childhood were included, and profiling was performed on plasma samples collected at ages 1 and 6 years. Both cohorts recorded incidence of lower respiratory infections, upper respiratory infections, ear infections, and colds. Poisson regression analysis assessed the associations between 18 steroid metabolites and the total number of respiratory infections that occurred in offspring during follow-up. We found that steroid metabolites across androgenic, corticosteroid, pregnenolone, and progestin classes were reduced in children that suffered more infections, and these patterns persisted at age 6 years, generally reflecting consistency in direction of effect and significance. Our analysis suggested steroid metabolite measurement may be useful in screening for infection proneness during this critical developmental period. Future studies should clinically evaluate their potential utility as a clinical screening tool.

Impact of the COVID-19 pandemic on asthma control among children: a qualitative study from caregivers' perspectives and experiences

OBJECTIVES

To understand the impact of the COVID-19 epidemic on asthma control in children based on caregivers' perspectives and experiences.

DESIGN

This was a qualitative study deploying face-to-face, semistructured interviews. Thematic analysis was carried out to analyse the data.

SETTING

Paediatric respiratory clinics in three tertiary hospitals.

PARTICIPANTS

16 caregivers providing unpaid asthma-related care and assistance to children under 14 years who had been diagnosed with asthma for more than 1 year and were not only treated with short-acting β2-agonists.

RESULTS

Six main themes were identified: (1) improved asthma control; (2) decreased willingness to seek medical care driven by fear; (3) increased adherence due to enhanced awareness of asthma control; (4) coping strategies for changes caused by COVID-19; (5) a new opportunity and (6) managing new challenges in asthma control.

CONCLUSIONS

The COVID-19 outbreak and the measures in response to it have had significant impacts on asthma control among children. Children with asthma are advised to continue good asthma management, take their prescribed asthma medications as normal, wash their hands regularly and wear face masks. Regularly supported self-management and remote consultations should be provided during the COVID-19 pandemic. In addition, supporting people financially, providing continued medical support and alleviating any fear and anxiety should be considered. We anticipate that our findings will inform health promotion interventions.

Poria cocos Modulates Th1/Th2 Response and Attenuates Airway Inflammation in an Ovalbumin-Sensitized Mouse Allergic Asthma Model

Poria cocos, called fuling, is a famous tonic in traditional Chinese medicine that reportedly possesses various pharmacological properties, including anti-inflammation and immunomodulation. However, few studies have investigated the effects of P. cocos on allergic diseases, such as allergic asthma. Allergic asthma is caused primarily by Th2 immune response and characterized by airway inflammation. This study first demonstrated the anti-allergic and anti-asthmatic effects of P. cocos extract (Lipucan^®). P. cocos extract distinctly exhibited reduced inflammatory cell infiltration in the peribronchial and peribronchiolar regions compared to the asthma group in the histological analysis of pulmonary tissue sections. Prolonged P. cocos extract administration significantly reduced eosinophil infiltration, PGE2 levels, total IgE, and OVA-specific IgE. Moreover, P. cocos extract markedly suppressed Th2 cytokines, IL-4, IL-5, and IL-10. On the other hand, P. cocos extract significantly elevated IL-2 secretion by Th1 immune response. In addition, P. cocos extract elevated the IFN-γ level at a lower dose. We also observed that P. cocos extract increased the activity of NK cells. Our results suggest that P. cocos extract remodels the intrinsic Th1/Th2 response to prevent or alleviate allergy-induced asthma or symptoms.

Allergic inflammation alters the lung microbiome and hinders synergistic co-infection with H1N1 influenza virus and Streptococcus pneumoniae in C57BL/6 mice

Asthma is a chronic airways condition that can be exacerbated during respiratory infections. Our previous work, together with epidemiologic findings that asthmatics were less likely to suffer from severe influenza during the 2009 pandemic, suggest that additional complications of influenza such as increased susceptibility to bacterial superinfection, may be mitigated in allergic hosts. To test this hypothesis, we developed a murine model of 'triple-disease' in which mice rendered allergic to Aspergillus fumigatus were co-infected with influenza A virus and Streptococcus pneumoniae seven days apart. Significant alterations to known synergistic effects of co-infection were noted in the allergic mice including reduced morbidity and mortality, bacterial burden, maintenance of alveolar macrophages, and reduced lung inflammation and damage. The lung microbiome of allergic mice differed from that of non-allergic mice during co-infection and antibiotic-induced perturbation to the microbiome rendered allergic animals susceptible to severe morbidity. Our data suggest that responses to co-infection in allergic hosts likely depends on the immune and microbiome states and that antibiotics should be used with caution in individuals with underlying chronic lung disease.

A randomized controlled trial of a mobile application-assisted nurse-led model used to improve treatment outcomes in children with asthma

AIM

To evaluate the effectiveness of a mobile application-assisted nurse-led management model in childhood asthma.

BACKGROUND

Studies have shown that a nurse-led asthma management model can improve asthma outcomes. However, the role of a mobile application-assisted nurse-led model in paediatric asthma management has not been studied well.

DESIGN

A multi-centre randomized clinical trial.

METHODS

The trial was conducted between March 2017-March 2018. A total of 152 children (6 to 11.9 years old) were enrolled, with 77 children in the experimental group and 75 in the control group. All children received nurse-led asthma management and other routine treatment measures, including inhaled corticosteroids. Meanwhile, a mobile application was used to manage asthma only for children in the experimental group. Primary outcome was frequency of asthma exacerbations. All outcomes were evaluated twice a month for 12 months.

RESULTS

Compared with the pre-enrollment period, frequency of asthma exacerbations decreased in the post-enrollment period in the two groups, with a greater decrease in the experimental group. Compared with children in the control group, children in the experimental group had better secondary outcomes, such as improved adherence, higher Childhood Asthma Control Test scores, decreased respiratory tract infections, days of antibiotic use, days of school absence, parental work loss, and medical expenses.

CONCLUSION

A mobile application-assisted nurse-led management model decreased asthma exacerbations and improved secondary outcomes in children with asthma. Further research is needed to verify its validity in larger population samples.

IMPACT

Children with asthma benefited from a nurse-led asthma management model when combined with mobile application. This trial suggested that computer and Internet technologies should be incorporated into nurse-led asthma strategy in paediatric asthma management.

TRIAL REGISTRATION

The current trial was registered online with the Chinese Clinical Trial Registry (registration number: ChiCTR1800016726).

House dust mite exposure attenuates influenza A infection in a mouse model of pulmonary allergic inflammation

Environmental allergens elicit complex immune responses in the lungs that can promote the development of asthma or exacerbate preexisting asthma in susceptible individuals. House dust mites are one of the most common indoor allergens and are a significant driver of allergic disease. Respiratory infections are known factors in acute exacerbations of asthma but the impact of allergen on the pathogen is not well understood. We investigated the pathogenesis of influenza A infection following exposure to house dust mites. Mice exposed to house dust mites lose less weight following infection and had more transcription of interferon-lambda than controls. These data correlated with less transcription of the influenza polymerase acidic gene suggesting diminished viral replication in house dust mite exposed mice. Altogether, these data suggest that exposure to environmental allergens can influence the pathogenesis of influenza infection.

Determinants of inter-practice variation in childhood asthma and respiratory infections: cross-sectional study of a national sentinel network

OBJECTIVES

Respiratory infections are associated with acute exacerbations of asthma and accompanying morbidity and mortality. In this study we explore inter-practice variations in respiratory infections in children with asthma and study the effect of practice-level factors on these variations.

DESIGN

Cross-sectional study.

SETTING

We analysed data from 164 general practices in the Royal College of General PractitionersResearch and Surveillance Centresentinel network in England.

PARTICIPANTS

Children 5-12 years.

INTERVENTIONS

None. In this observational study, we used regression analysis to explore the impact of practice-level determinants on the number of respiratory infections in children with asthma.

PRIMARY AND SECONDARY OUTCOME MEASURES

We describe the distribution of childhood asthma and the determinants of upper/lower respiratory tract infections in these children.

RESULTS

83.5% (137/164) practices were in urban locations; the mean number of general practitioners per practice was 7; and the mean duration since qualification 19.7 years. We found almost 10-fold difference in the rate of asthma (1.5-11.8 per 100 children) and 50-fold variation in respiratory infection rates between practices. Larger practices with larger lists of asthmatic children had greater rates of respiratory infections among these children.

CONCLUSION

We showed that structural/environmental variables are consistent predictors of a range of respiratory infections among children with asthma. However, contradictory results between measures of practice clinical care show that a purely structural explanation for variability in respiratory infections is limited. Further research is needed to understand how the practice factors influence individual risk behaviours relevant to respiratory infections.

Superinfection and cell regeneration can lead to chronic viral coinfections

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Clinical researchers have found that coinfection of the respiratory tract can cause distinct disease outcome, sometimes leading to long-lasting infection, compared to single viral infection.

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The impact of coinfections in human respiratory tract have not yet been evaluated in either theoretical or experimental studies on a large scale.

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A few experiments confirm that different respiratory viruses can infect the same cell (superinfection).

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Superinfection alone cannot cause long-lasting viral coinfections.

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The combined mechanism of superinfection and cell regeneration provides a plausible mechanism for chronic viral coinfections.

Molecular diagnostic techniques have revealed that approximately 43% of the patients hospitalized with influenza-like illness are infected by more than one viral pathogen, sometimes leading to long-lasting infections. It is not clear how the heterologous viruses interact within the respiratory tract of the infected host to lengthen the duration of what are usually short, self-limiting infections. We develop a mathematical model which allows for single cells to be infected simultaneously with two different respiratory viruses (superinfection) to investigate the possibility of chronic coinfections. We find that a model with superinfection and cell regeneration has a stable chronic coinfection fixed point, while superinfection without cell regeneration produces only acute infections. This analysis suggests that both superinfection and cell regeneration are required to sustain chronic coinfection via this mechanism since coinfection is maintained by superinfected cells that allow slow-growing infections a chance to infect cells and continue replicating. This model provides a possible mechanism for chronic coinfection independent of any viral interactions via the immune response.

Prevalence and determinants of asthma among aboriginal adolescents in Canada

Objective: The objective of the study was to determine the prevalence and associated risk factors of asthma in Aboriginal adolescents in Canada based on the Canadian Aboriginal Peoples Survey (APS) 2012. Few studies have investigated the prevalence and risk factors of asthma in Aboriginal adolescents in Canada. Methods: Data from the cross-sectional APS 2012 were analyzed to accomplish the objective. Logistic regression analysis was utilized to determine significant risk factors of lifetime diagnosis of asthma among Aboriginal adolescents. The outcome of interest for adolescents was based on the question: "Do you have asthma that have been diagnosed by a health professional?" Individual, environmental, and contextual factors were tested for an association with lifetime diagnosis of asthma among adolescents. Results: The overall prevalence of lifetime diagnosis of asthma was 16.0%. The prevalence of lifetime diagnosis of asthma was 16.8% for adolescent boys and 15.3% for adolescent girls. Based on multivariable logistic regression analysis, the risk factors of lifetime diagnosis of asthma were: age, income, being overweight, smoking inside the home, having one to two children under 18 years in the household, history of bronchitis, living in an urban residence, education, and geographical location. Female sex was reported to have a protective effect on or reduce risk of the prevalence of lifetime diagnosis of asthma compared to the male sex. Conclusions: Lifetime diagnosis of asthma prevalence appears to be lower in Aboriginal adolescent girls than in adolescent boys. Lifetime diagnosis of asthma prevalence in these adolescents is associated with age, income, education, being overweight, smoking inside the home, history of bronchitis, and location of residence, both geographical region and urban residence. The prevalence of lifetime diagnosis of asthma among Aboriginal adolescent is higher compared to the general adolescent population in Canada.

A guide to polarized airway epithelial models for studies of host-pathogen interactions

Mammalian lungs are organs exhibiting the cellular and spatial complexity required for gas exchange to support life. The respiratory epithelium internally lining the airways is susceptible to infections due to constant exposure to inhaled microbes. Biomedical research into respiratory bacterial infections in humans has been mostly carried out using small mammalian animal models or two-dimensional, submerged cultures of undifferentiated epithelial cells. These experimental model systems have considerable limitations due to host specificity of bacterial pathogens and lack of cellular and morphological complexity. This review describes the in vitro differentiated and polarized airway epithelial cells of human origin that are used as a model to study respiratory bacterial infections. Overall, these models recapitulate key aspects of the complexity observed in vivo and can help in elucidating the molecular details of disease processes observed during respiratory bacterial infections.

A viral-vectored RSV vaccine induces long-lived humoral immunity in cotton rats

Human respiratory syncytial virus (RSV) is the leading cause of lower airway disease in infants worldwide and repeatedly infects immunocompetent individuals throughout life. Severe lower airway RSV infection during infancy can be life-threatening, but is also associated with important sequelae including development of asthma and recurrent wheezing in later childhood. The basis for the inadequate, short-lived adaptive immune response to RSV infection is poorly understood, but it is widely recognized that RSV actively antagonizes Type I interferon (IFN) production. In addition to the induction of the anti-viral state, IFN production during viral infection is critical for downstream development of robust, long-lived immunity. Based on the hypothesis that a vaccine that induced robust IFN production would be protective, we previously constructed a Newcastle disease virus-vectored vaccine that expresses the F glycoprotein of RSV (NDV-F) and demonstrated that vaccinated mice had reduced lung viral loads and an enhanced IFN-γ response after RSV challenge. Here we show that vaccination also protected cotton rats from RSV challenge and induced long-lived neutralizing antibody production, even in RSV immune animals. Finally, pulmonary eosinophilia induced by RSV infection of unvaccinated cotton rats was prevented by vaccination. Overall, these data demonstrate enhanced protective immunity to RSV F when this protein is presented in the context of an abortive NDV infection.

Developments in the field of allergy mechanisms in 2015 through the eyes of Clinical & Experimental Allergy

In the first of two papers we described the development in the field of allergy mechanisms as described by Clinical and Experimental Allergy in 2015. Experimental models of allergic disease, basic mechanisms, clinical mechanisms and allergens are all covered. A second paper will cover clinical aspects.

IL-17 and TNF-α Are Key Mediators of Moraxella catarrhalis Triggered Exacerbation of Allergic Airway Inflammation

Alterations of the airway microbiome are often associated with pulmonary diseases. For example, detection of the bacterial pathogen Moraxella catarrhalis in the upper airways is linked with an increased risk to develop or exacerbate asthma. However, the mechanisms by which M. catarrhalis augments allergic airway inflammation (AAI) remain unclear. We here characterized the cellular and soluble mediators of M. catarrhalis triggered excacerbation of AAI in wt and IL-17 deficient as well as in animals treated with TNF-α and IL-6 neutralizing antibodies. We compared the type of inflammatory response in M. catarrhalis infected, house dust mite (HDM)-allergic and animals infected with M. catarrhalis at different time points of HDM sensitization. We found that airway infection of mice with M. catarrhalis triggers a strong inflammatory response with massive neutrophilic infiltrates, high amounts of IL-6 and TNF-α and moderate levels of CD4⁺ T-cell-derived IFN-γ and IL-17. If bacterial infection occurred during HDM allergen sensitization, the allergic airway response was exacerbated, particularly by the expansion of Th17 cells and increased TNF-α levels. Neutralization of IL-17 or TNF-α but not IL-6 resulted in accelerated clearance of M. catarrhalis and effectively prevented infection-induced exacerbation of AAI. Taken together, our data demonstrate an essential role for TNF-α and IL-17 in infection-triggered exacerbation of AAI.

Multiplicity of Mathematical Modeling Strategies to Search for Molecular and Cellular Insights into Bacteria Lung Infection

Even today two bacterial lung infections, namely pneumonia and tuberculosis, are among the 10 most frequent causes of death worldwide. These infections still lack effective treatments in many developing countries and in immunocompromised populations like infants, elderly people and transplanted patients. The interaction between bacteria and the host is a complex system of interlinked intercellular and the intracellular processes, enriched in regulatory structures like positive and negative feedback loops. Severe pathological condition can emerge when the immune system of the host fails to neutralize the infection. This failure can result in systemic spreading of pathogens or overwhelming immune response followed by a systemic inflammatory response. Mathematical modeling is a promising tool to dissect the complexity underlying pathogenesis of bacterial lung infection at the molecular, cellular and tissue levels, and also at the interfaces among levels. In this article, we introduce mathematical and computational modeling frameworks that can be used for investigating molecular and cellular mechanisms underlying bacterial lung infection. Then, we compile and discuss published results on the modeling of regulatory pathways and cell populations relevant for lung infection and inflammation. Finally, we discuss how to make use of this multiplicity of modeling approaches to open new avenues in the search of the molecular and cellular mechanisms underlying bacterial infection in the lung.

Osthole treatment ameliorates Th2-mediated allergic asthma and exerts immunomodulatory effects on dendritic cell maturation and function

Osthole, an active component of Chinese herbal medicines, reportedly possesses various pharmacological properties and has potential therapeutic applications. This study explored the anti-allergic effects of osthole in asthmatic mice and investigated the immunomodulatory actions of osthole on dendritic cells (DCs) and T cells. Herein, we show that oral administration of osthole to BALB/c mice after ovalbumin (OVA) sensitization ameliorated all of the cardinal features of T helper 2 (Th2)-mediated allergic asthma; namely, the production of OVA-specific immunoglobulin E, airway hyperresponsiveness, airway inflammation and the production of Th2-type cytokines including interleukin (IL)-4, IL-5 and IL-13. Surprisingly, IL-10 production was not inhibited and was even enhanced by osthole treatment. We observed a significant increase in the percentages of IL-10-producing DCs and forkhead box P3-positive regulatory T (Treg) cells in osthole-treated asthmatic mice. Additionally, in vitro analyses revealed that osthole-treated bone-marrow-derived DCs had a partial maturation phenotype, secreting large amounts of IL-10 and low levels of proinflammatory cytokines, such as IL-12, IL-6 and tumor necrosis factor-α, and displaying reduced levels of MHC class II surface molecules. These DCs displayed immunosuppressive capacity by directly inhibiting effector T-cell responses or inducing Treg cells. In addition, osthole directly inhibited the activated CD4+ T-cell proliferation and Th1/Th2-type cytokine production in this system. Collectively, these results suggest that DCs and T cells are potential target cells responsible for the action of osthole against allergic asthma.Cellular &Molecular Immunology advance online publication, 7 August 2017; doi:10.1038/cmi.2017.71.

The impact of cell regeneration on the dynamics of viral coinfection

Many mathematical models of respiratory viral infections do not include regeneration of cells within the respiratory tract, arguing that the infection is resolved before there is significant cellular regeneration. However, recent studies have found that ∼40% of patients hospitalized with influenza-like illness are infected with at least two different viruses, which could potentially lead to longer-lasting infections. In these longer infections, cell regeneration might affect the infection dynamics, in particular, allowing for the possibility of chronic coinfections. Several mathematical models have been used to describe cell regeneration in infection models, though the effect of model choice on the predicted time course of viral coinfections is not clear. We investigate four mathematical models incorporating different mechanisms of cell regeneration during respiratory viral coinfection to determine the effect of cell regeneration on infection dynamics. We perform linear stability analysis for each of the models and find the steady states analytically. The analysis suggests that chronic illness is possible but only with one viral species; chronic coexistence of two different viral species is not possible with the regeneration models considered here.

Association of hospitalizations for asthma with seasonal and pandemic influenza

BACKGROUND AND OBJECTIVE

Although influenza has been associated with asthma exacerbations, it is not clear the extent to which this association affects health care use in the United States. The first goal of this project was to determine whether, and to what extent, the incidence of asthma hospitalizations is associated with seasonal variation in influenza. Second, we used influenza trends (2000-2008) to help predict asthma admissions during the 2009 H1N1 influenza pandemic.

METHODS

We identified all hospitalizations between 1998 and 2008 in the Nationwide Inpatient Sample from the Healthcare Cost and Utilization Project during which a primary diagnosis of asthma was recorded. Separately, we identified all hospitalizations during which a diagnosis of influenza was recorded. We performed time series regression analyses to investigate the association of monthly asthma admissions with influenza incidence. Finally, we applied these time series regression models using 1998-2008 data, to forecast monthly asthma admissions during the 2009 influenza pandemic.

RESULTS

Based on time series regression models, a strong, significant association exists between concurrent influenza activity and incidence of asthma hospitalizations (P-value < 0.0001). Use of influenza data to predict asthma admissions during the 2009 H1N1 pandemic improved the mean squared prediction error by 60.2%.

CONCLUSIONS

Influenza activity in the population is significantly associated with asthma hospitalizations in the United States, and this association can be exploited to more accurately forecast asthma admissions. Our results suggest that improvements in influenza surveillance, prevention and treatment may decrease hospitalizations of asthma patients.

Update on anticytokine treatment for asthma

Current advances in the knowledge of asthma pathobiology suggest that anticytokine therapies can be potentially useful for the treatment of this complex and heterogeneous airway disease. Recent evidence is accumulating in support of the efficacy of anti-IL-4, anti-IL-5, and anti-IL-13 drugs. Therefore, these new developments are now changing the global scenario of antiasthma therapies, especially with regard to more severe disease. Current findings referring to variability of individual therapeutic responses highlight that the different asthma subtypes need to be well characterized, in order to implement phenotype-targeted treatments which in the near future will hopefully be mainly based on cytokine-directed biologics.

Effect of non-human neutral and acidic oligosaccharides on allergic and infectious diseases in preterm infants

Short-term supplementation of non-human neutral and acidic oligosaccharides during the first postnatal weeks may enhance the maturation of the immune response in preterm infants and may lead to less allergic and infectious diseases during the first year of life. In a randomized controlled trial, 113 preterm infants (gestational age <32 weeks and/or birth weight <1500 g) were allocated to receive enteral neutral and acidic oligosaccharide supplementation or placebo between days 3 and 30 of life. The median age at follow-up was not different in both groups: 12 months corrected age (interquartile range [IQR], 11-15) in the prebiotic mixture group and 12 months corrected age in the placebo group (IQR, 10-19), respectively. In addition, baseline patient, maternal, and environmental characteristics were not different between the prebiotic mixture (n = 48) and placebo (n = 46) group. Incidence of allergic and infectious diseases was assessed by validated questionnaires. In total, 94/98 (96 %) of the eligible, surviving infants participated in this follow-up study. The incidence of atopic dermatitis (odds ratio [OR], 0.80; 95 % confidence interval [CI], 0.24-2.67), bronchial hyper-reactivity (OR, 1.04; 95 % CI, 0.38-2.87) and infections of the upper respiratory (OR, 0.95; 95 % CI, 0.37-2.44), lower respiratory (OR, 1.03; 95 % CI, 0.37-2.88), and gastrointestinal (OR, 1.77; 95 % CI, 0.55-5.73) tract was not different between the groups. Adjustment for potential confounding factors did not change the results of the primary analysis.

CONCLUSION

Short-term enteral supplementation of non-human neutral and acidic oligosaccharides during the neonatal period in preterm infants does not decrease the incidence of allergic and infectious diseases during the first year of life.

SHP-1 as a critical regulator of Mycoplasma pneumoniae-induced inflammation in human asthmatic airway epithelial cells

Asthma is a chronic inflammatory disease in which airway epithelial cells are the first line of defense against exposure of the airway to infectious agents. Src homology protein (SHP)-1, a protein tyrosine phosphatase, is a negative regulator of signaling pathways that are critical to the development of asthma and host defense. We hypothesize that SHP-1 function is defective in asthma, contributing to the increased inflammatory response induced by Mycoplasma pneumoniae, a pathogen known to exacerbate asthma. M. pneumoniae significantly activated SHP-1 in airway epithelial cells collected from nonasthmatic subjects by bronchoscopy with airway brushing but not in cells from asthmatic subjects. In asthmatic airway epithelial cells, M. pneumoniae induced significant PI3K/Akt phosphorylation, NF-κB activation, and IL-8 production compared with nonasthmatic cells, which were reversed by SHP-1 overexpression. Conversely, SHP-1 knockdown significantly increased IL-8 production and PI3K/Akt and NF-κB activation in the setting of M. pneumoniae infection in nonasthmatic cells, but it did not exacerbate these three parameters already activated in asthmatic cells. Thus, SHP-1 plays a critical role in abrogating M. pneumoniae-induced IL-8 production in nonasthmatic airway epithelial cells through inhibition of PI3K/Akt and NF-κB activity, but it is defective in asthma, resulting in an enhanced inflammatory response to infection.

Surfactant protein-A suppresses eosinophil-mediated killing of Mycoplasma pneumoniae in allergic lungs

Surfactant protein-A (SP-A) has well-established functions in reducing bacterial and viral infections but its role in chronic lung diseases such as asthma is unclear. Mycoplasma pneumoniae (Mp) frequently colonizes the airways of chronic asthmatics and is thought to contribute to exacerbations of asthma. Our lab has previously reported that during Mp infection of non-allergic airways, SP-A aides in maintaining airway homeostasis by inhibiting an overzealous TNF-alpha mediated response and, in allergic mice, SP-A regulates eosinophilic infiltration and inflammation of the airway. In the current study, we used an in vivo model with wild type (WT) and SP-A^−/− allergic mice challenged with the model antigen ovalbumin (Ova) that were concurrently infected with Mp (Ova+Mp) to test the hypothesis that SP-A ameliorates Mp-induced stimulation of eosinophils. Thus, SP-A could protect allergic airways from injury due to release of eosinophil inflammatory products. SP-A deficient mice exhibit significant increases in inflammatory cells, mucus production and lung damage during concurrent allergic airway disease and infection (Ova+Mp) as compared to the WT mice of the same treatment group. In contrast, SP-A deficient mice have significantly decreased Mp burden compared to WT mice. The eosinophil specific factor, eosinophil peroxidase (EPO), which has been implicated in pathogen killing and also in epithelial dysfunction due to oxidative damage of resident lung proteins, is enhanced in samples from allergic/infected SP-A^−/− mice as compared to WT mice. In vitro experiments using purified eosinophils and human SP-A suggest that SP-A limits the release of EPO from Mp-stimulated eosinophils thereby reducing their killing capacity. These findings are the first to demonstrate that although SP-A interferes with eosinophil-mediated biologic clearance of Mp by mediating the interaction of Mp with eosinophils, SP-A simultaneously benefits the airway by limiting inflammation and damage.

Mice with asthma are more resistant to influenza virus infection and NK cells activated by the induction of asthma have potentially protective effects

Purpose

This study was conducted in order to investigate whether the virulence of the influenza virus infection is affected by asthma in mice.

Methods

Mice with asthma or control mice were infected with influenza virus. The survival rate, body weight, virus titer, cytokine profile, and cell infiltration in bronchoalveolar lavage fluid (BALF) were measured. The NK cell cytotoxicity was determined by a co-culture system with YAC-1 cells, and the effects of NK cells were observed by depletion of NK cells using anti-asialoGM1 serum. The virus-specific CD8⁺ T cell killing assay was also performed.

Results

When asthmatic or control mice were infected with non- and sub-lethal doses of influenza virus, the asthmatic mice were more resistant to the virus than control mice with regard to the survival rate, the remission of body weight loss, and the virus burden. Anti-viral cytokines and the NK cell number were increased in the BALF of asthmatic mice before the infection. The NK cell cytotoxicity in the asthmatic mice was significantly enhanced compared to that in control mice, and the depletion of NK cells in asthmatic mice was abrogated both the improved survival rate and the recovery of the body weight loss. The antigen-specific CD8⁺ T cell killing activity in asthmatic mice was also significantly increased following the infection compared to that in control mice.

Conclusion

NK cell activated by the induction of asthma and the subsequently activated antigen-specific CD8⁺ T cells could promptly eliminate the viral-infected cells, thus leading to improvements in the morbidity and mortality of influenza virus infection.

The role of toll-like receptors in acute and chronic lung inflammation

By virtue of its direct contact with the environment, the lung is constantly challenged by infectious and non-infectious stimuli that necessitate a robust yet highly controlled host response coordinated by the innate and adaptive arms of the immune system. Mammalian Toll-like receptors (TLRs) function as crucial sentinels of microbial and non-infectious antigens throughout the respiratory tract and mediate host innate immunity. Selective induction of inflammatory responses to harmful environmental exposures and tolerance to innocuous antigens are required to maintain tissue homeostasis and integrity. Conversely, dysregulated innate immune responses manifest as sustained and self-perpetuating tissue damage rather than controlled tissue repair. In this article we review aspects of Toll-like receptor function that are relevant to the development of acute lung injury and chronic obstructive lung diseases as well as resistance to frequently associated microbial infections.

Relationships between Cytokine Profiles and Signaling Pathways (IκB Kinase and p38 MAPK) in Parainfluenza Virus-Infected Lung Fibroblasts

Respiratory viruses such as parainfluenza virus (PIV) in individuals with certain genetic predispositions in early life are associated with the induction of wheezing, which can progress to the development of asthma. It has been suggested that aberrant production of various cytokines due to viral infection are associated with virus-induced asthma. However, the mechanisms of how respiratory viruses induce and exacerbate asthma have yet to be clarified. To examine cytokine responses to PIV infection, we assessed 27 cytokine levels released from PIV-infected human fetal lung fibroblasts. In addition, we examined relationships between these cytokine responses and signaling pathways (IκB kinase and p38 MAPK) in PIV-infected cells. At 24 h after infection, PIV-infected cells significantly released a number of cytokines, namely, proinflammatory cytokines [interleukins (IL)-1β, IL-6, and tumor necrosis factor-α], anti-inflammatory cytokine (IL-1ra), Th1 cytokines (interferon-γ, and IL-2), Th2 cytokines (IL-4, IL-5, and IL-10), granulopoiesis-inducing cytokines (granulocyte colony-stimulating factor and granulocyte–macrophage colony-stimulating factor), neutrophil recruitment-inducing cytokines (IL-8 and interferon-inducible protein-10), and eosinophil recruitment-inducing cytokines (eotaxin and regulated on activation normal T-cell expressed and secreted). PIV infection enhanced phosphorylation of both IκB and p38 MAPK, but not Akt, in the cells. Signaling pathway inhibitors, BMS-345541 (a specific IκB kinase inhibitor) and SB203580 (a specific p38 MAPK inhibitor), significantly suppressed release of these cytokines from PIV-infected cells. The results indicate that PIV infection induces aberrant production and release of various cytokines through IκB kinase and p38 MAPK pathways in human lung fibroblasts. Overproduction and imbalance of these cytokines may be partially associated with the pathophysiology of virus-induced asthma.

The Asthma Insights and Reality in the Maghreb (AIRMAG) study: perspectives and lessons

Asthma is the most frequently encountered allergic respiratory disease, and one that has a potentially serious impact on patients' functioning and well-being. From a public health perspective, it is important to collect data on the prevalence, burden and management of asthma in order to improve understanding of the pathogenesis of asthma and to ensure that national healthcare policies are adapted and appropriate. In this respect, the different AIR surveys, which have collected standardised data on asthma in the general population of a large number of countries around the world, have made an important contribution. The latest of these surveys is the AIRMAG survey, performed in the three Maghreb countries of Algeria, Morocco and Tunisia. In these countries, the prevalence of asthma (3.4% to 3.9%) is in the low to moderate range. This is consistent with rates observed elsewhere in the Mediterranean basin. Nonetheless, the prevalence of asthma in the Maghreb may be expected to rise in the future as populations become more urbanized and adopt a more 'Westernized' lifestyle. Indeed the prevalence of asthma is already higher in the urban coastal regions of these countries than in the more rural mountainous and desert regions. Asthma control in the Maghreb is relatively poor compared to other regions evaluated in previous AIR studies, with control being unacceptable in around three-quarters of respondents. Although part of the explanation may reside in limited access to care, treatment rates for inhaled corticosteroids (26.1% of adults and 29.1% of children) were no worse than those reported in previous AIR studies. On the other hand, asthma monitoring through regular follow-up visits, home flow-meter use and preparation of individualised asthma management plans was in general unsatisfactory. In addition, awareness of asthma in the general population of the Maghreb countries was low. Education measures directed at the patient, together with programmes directed at the physician to ensure systematic monitoring and the use of a 'treat to target' approach to therapy, could do much to increase quality of life and minimise restrictions on activities in patients with asthma in the Maghreb.

Review: Collectins link innate and adaptive immunity in allergic airway disease

Although the lipoprotein complex of pulmonary surfactant has long been recognized as essential for reducing lung surface tension, its role in lung immune host defense has only relatively recently been elucidated. Surfactant-associated proteins A (SP-A) and D (SP-D) can attenuate bacterial and viral infection and inflammation by acting as opsonins and by regulating innate immune cell functions. Surfactant-associated protein A and D also interact with antigen-presenting cells and T cells, thereby linking the innate and adaptive immune systems. A recent study from our laboratory demonstrated that mice deficient in SP-A have enhanced susceptibility to airway hyper-responsiveness and lung inflammation induced by Mycoplasma pneumonia, an atypical bacterium present in the airways of approximately 50% of asthmatics experiencing their first episode, and further supports an important role for SP-A in the host response to allergic airway disease. Animal and human studies suggest that alterations in the functions or levels of SP-A and SP-D are associated with both infectious and non-infectious chronic lung diseases such as asthma. Future studies are needed to elucidate whether alterations in SP-A and SP-D are a consequence and/or cause of allergic airway disease.

The impact of viral respiratory infection on the severity and recovery from an asthma exacerbation

BACKGROUND

: Viral respiratory illness triggers asthma exacerbations, but the influence of respiratory illness on the acute severity and recovery of childhood asthma is unknown. Our objective was to evaluate the impact of a concurrent acute respiratory illness (based on a clinical definition and PCR detection of a panel of respiratory viruses, Mycoplasma pneumoniae and Chlamydia pneumoniae) on the severity and resolution of symptoms in children with a nonhospitalized exacerbation of asthma.

METHODS

: Subjects were children aged 2 to 15 years presenting to an emergency department for an acute asthma exacerbation and not hospitalized. Acute respiratory illness (ARI) was clinically defined. Nasopharyngeal aspirates (NPA) were examined for respiratory viruses, Chlamydia and Mycoplasma using PCR. The primary outcome was quality of life (QOL) on presentation, day 7 and day 14. Secondary outcomes were acute asthma severity score, asthma diary, and cough diary scores on days 5, 7, 10, and 14.

RESULTS

: On multivariate regression, presence of ARI was statistically but not clinically significantly associated with QOL score on presentation (B = -0.36, P = 0.025). By day 7 and 14, there was no difference between groups. Asthma diary score was significantly higher in children with ARI (B = 0.41, P = 0.039) on day 5 but not on presentation or subsequent days. Respiratory viruses were detected in 54% of the 78 NPAs obtained. There was no difference in the any of the asthma outcomes of children grouped by positive or negative NPA.

CONCLUSIONS

: The presence of a viral respiratory illness has a modest influence on asthma severity, and does not influence recovery from a nonhospitalized asthma exacerbation.

Modified adenine (9-benzyl-2-butoxy-8-hydroxyadenine) redirects Th2-mediated murine lung inflammation by triggering TLR7

Substitute adenine (SA)-2, a synthetic heterocycle chemically related to adenine with substitutions in positions 9-, 2-, and 8- (i.e., 9-benzyl-2-butoxy-8-hydroxyadenine), induces in vitro immunodeviation of Th2 cells to a Th0/Th1 phenotype. In this article, we evaluate the in vivo ability of SA-2 to affect Th2-mediated lung inflammation and its safety. TLR triggering and NF-kappaB activation by SA-2 were analyzed on TLR-transfected HEK293 cells and on purified bone marrow dendritic cells. The in vivo effect of SA-2 on experimental airway inflammation was evaluated in both prepriming and prechallenge protocols by analyzing lung inflammation, including tissue eosinophilia and goblet cell hyperplasia, bronchoalveolar lavage fluid cell types, and the functional profile of Ag-specific T cells from draining lymph nodes and spleens. SA-2 induced mRNA expression and production of proinflammatory (IL-6, IL-12, and IL-27) and regulatory (IL-10) cytokines and chemokines (CXCL10) in dendritic cells but down-regulated TGF-beta. Prepriming administration of SA-2 inhibited OVA-specific Abs and Th2-driven lung inflammation, including tissue eosinophilia and goblet cells, with a prevalent Foxp3-independent regulatory mechanism. Prechallenge treatment with SA-2 reduced the lung inflammation through the induction of a prevalent Th1-related mechanism. In this model the activity of SA-2 was route-independent, but adjuvant- and Ag dose-dependent. SA-2-treated mice did not develop any increase of serum antinuclear autoantibodies. In conclusion, critical substitutions in the adenine backbone creates a novel synthetic TLR7 ligand that shows the ability to ameliorate Th2-mediated airway inflammation by a complex mechanism, involving Th1 redirection and cytokine-mediated regulation, which prevents autoreactivity.

The role of infection in asthma

This paper reviews the impact of infections on the onset and clinical course of bronchial asthma. A just emphasis is given to the role viral infections, particularly rhinovirus infections, play in exacerbations, and that played by respiratory syncytial virus, suspected of triggering the asthmatic syndrome. The mechanisms of the immune response to virus attacks are explained, highlighting the asthmatic and allergic patient's weakened response, particularly in the perinatal period. Further stressed is a potentiating effect of viral aggression on the allergic response. The hygiene hypothesis and its lack of scientific consistency is detailed, at least as far as the role it seeks to confer on an unproven antagonism of the Th1 and Th2 lymphocyte responses. The current importance of research not into bacteria, but into bacterial products, including endotoxins, on the modulation of asthma and allergy is noted. Studies which, along these lines, show an environmental impact on genetic secretion in the phenotype are underlined. Also discussed in passing are several mechanisms which go towards explaining neutrophilic asthma - for many a contradiction, given eosinophilia's stranglehold on asthmatic inflammation.

Infecção na modulaçâo da asma11Trabalho apresentado no XXIII Congresso de Pneumologia da SPP – Guarda, Novembro 2007 / Paper presented at the XXIII Congresso de Pneumologia da SPP / PSP Pulmonology Congress, Guarda, November 2007

Faz-se uma revisão da influência das infecções no aparecimento e na clínica da asma brônquica. Dá-se o relevo que merece à intervenção virusal, sobretudo ao rinovírus, pela sua influência nas exacerbações, e ao vírus sincicial respiratório, sobre o qual recai a suspeita de poder ser causa determinante no aparecimento da síndroma asmática. Tentam-se esclarecer os mecanismos da resposta imune à agressão virusal em função das debilidades da resposta do asmático e do atópico, sobretudo no período perinatal, salientando-se, ainda, um efeito de potenciação da agressão virusal sobre a resposta atópica. Aborda-se a hipótese higiénica e a sua falta de consistência científica, pelo menos no papel que pretende atribuir a um não demonstrado antagonismo das respostas linfocitárias Th₁ e Th_2, apontando-se a importância actual da investigação, não das bactérias mas dos produtos bacterianos, como as endotoxinas, na modulação da asma e da atopia, dando-se relevo aos estudos que, a partir deste modelo, demonstram uma influência do ambiente na secreção génica e, consequentemente, no fenótipo. Invocam-se, nas entrelinhas, vários mecanismos que podem explicar a asma neutrofílica que, para muitos, é um paradoxo perante o consagrado domínio do eosinófilo na inflamação asmática.

Rev Port Pneumol 2008; XIV (5): 647-675

The role of oseltamivir in the treatment and prevention of influenza in children

The burden of seasonal influenza in children is poorly recognized, in spite of the potential for severe and even life-threatening illness and common secondary complications. Children are a primary reservoir for the spread of influenza to both family members and the community, which imposes a sizeable social and economic strain. Although vaccination is the primary intervention against childhood influenza, the antiviral neuraminidase inhibitors, oseltamivir and zanamivir, provide treatment options. Oseltamivir is administered orally to children aged > 1 year and has been shown to cost-effectively reduce the influenza disease burden and duration of viral shedding. Additionally, oseltamivir postexposure prophylaxis provides protective efficacy for children and families. Oseltamivir has shown excellent tolerability and a low potential for viral resistance in pediatric studies. In the event of an influenza pandemic, oseltamivir is expected to be at the forefront of containment strategies. This article reviews the pharmacology, efficacy and tolerability of oseltamivir as treatment and prophylaxis in children.

Summing up 100 years of asthma

In this review, we aim to lead the readers through the historical highlights of pathophysiological concepts and treatment of asthma. Understanding the nature and links of asthma has modeled our diagnostic, pathophysiological and therapeutic thinking and acting. The recognition of its heterogeneous nature in combination with several refined and sophisticated technologies will mark a new era of phenotype-specific approach and treatment of asthma.

Prevalence of viral respiratory tract infections in children with asthma

Background

Previous studies support a strong association between viral respiratory tract infections and asthma exacerbations. The effect of newly discovered viruses on asthma control is less well defined.

Objective

We sought to determine the contribution of respiratory viruses to asthma exacerbations in children with a panel of PCR assays for common and newly discovered respiratory viruses.

Methods

Respiratory specimens from children aged 2 to 17 years with asthma exacerbations (case patients, n = 65) and with well-controlled asthma (control subjects, n = 77), frequency matched by age and season of enrollment, were tested for rhinoviruses, enteroviruses, respiratory syncytial virus, human metapneumovirus, coronaviruses 229E and OC43, parainfluenza viruses 1 to 3, influenza viruses, adenoviruses, and human bocavirus.

Results

Infection with respiratory viruses was associated with asthma exacerbations (63.1% in case patients vs 23.4% in control subjects; odds ratio, 5.6; 95% CI, 2.7- 11.6). Rhinovirus was by far the most prevalent virus (60% among case patients vs 18.2% among control subjects) and the only virus significantly associated with exacerbations (odds ratio, 6.8; 95% CI, 3.2-14.5). However, in children without clinically manifested viral respiratory tract illness, the prevalence of rhinovirus infection was similar in case patients (29.2%) versus control subjects (23.4%, P > .05). Other viruses detected included human metapneumovirus (4.6% in patients with acute asthma vs 2.6% in control subjects), enteroviruses (4.6% vs 0%), coronavirus 229E (0% vs 1.3%), and respiratory syncytial virus (1.5% vs 0%).

Conclusion

Symptomatic rhinovirus infections are an important contributor to asthma exacerbations in children.

Clinical implications

These results support the need for therapies effective against rhinovirus as a means to decrease asthma exacerbations.