Asthma: NHLBI Workshop on the Primary Prevention of Chronic Lung Diseases

Creatine Kinase Is Decreased in Childhood Asthma

Rationale: The identification of novel molecules associated with asthma may provide insights into the mechanisms of disease and their potential clinical implications. Objectives: To conduct a screening of circulating proteins in childhood asthma and to study proteins that emerged from human studies in a mouse model of asthma. Methods: We included 2,264 children from eight birth cohorts from the Mechanisms of the Development of ALLergy project and the Tucson Children's Respiratory Study. In cross-sectional analyses, we tested 46 circulating proteins for association with asthma in the selection stage and carried significant signals forward to a validation and replication stage. As CK (creatine kinase) was the only protein consistently associated with asthma, we also compared whole blood CK gene expression between subjects with and without asthma (n = 249) and used a house dust mite (HDM)-challenged mouse model to gain insights into CK lung expression and its role in the resolution of asthma phenotypes. Measurements and Main Results: As compared with the lowest CK tertile, children in the highest tertile had significantly lower odds for asthma in selection (adjusted odds ratio, 95% confidence interval: 0.31; 0.15-0.65; P = 0.002), validation (0.63; 0.42-0.95; P = 0.03), and replication (0.40; 0.16-0.97; P = 0.04) stages. Both cytosolic CK forms (CKM and CKB) were underexpressed in blood from asthmatics compared with control subjects (P = 0.01 and 0.006, respectively). In the lungs of HDM-challenged mice, Ckb expression was reduced, and after the HDM challenge, a CKB inhibitor blocked the resolution of airway hyperresponsiveness and reduction of airway mucin. Conclusions: Circulating concentrations and gene expression of CK are inversely associated with childhood asthma. Mouse models support a possible direct involvement of CK in asthma protection via inhibition of airway hyperresponsiveness and reduction of airway mucin.

Early priming of asthma and respiratory allergies: Future aspects of prevention: A statement by the European Forum for Education and Research in Allergy and Airway Disease (EUFOREA) and the EAACI-Clemens von Pirquet Foundation

In order to summarize recent research on the prevention of allergies-particularly asthma-and stimulate new activities for future initiatives, a virtual workshop sponsored by the EAACI Clemens von Pirquet foundation and EUFOREA was held in October 2021. The determinants of the "allergic march" as well as the key messages from intervention studies were reviewed by an international faculty of experts. Several unmet needs were identified, and a number of priorities for future studies were proposed.

Dexmedetomidine as an adjunctive treatment for acute asthma

Objective

This study aimed to compare the efficacy of using dexmedetomidine with salbutamol and salbutamol nebulization alone in patients with acute exacerbation of asthma presenting to the emergency department.

Methods

This clinical trial included 60 patients, in the age range of 18 to 55 years, with signs of bronchospasm presenting to the emergency department. In the intervention group, dexmedetomidine 0.5 µg/kg was injected intravenously and three doses of salbutamol nebulization were administered over 60 minutes. In the control group, salbutamol nebulization was administered for 60 minutes three times. The patient’s clinical status, based on clinical symptoms, consciousness, speech, breathing rate, heart rate, and blood pressure were recorded before the intervention, and peak expiratory flow rate and forced expiratory volume in 1 second were measured at 20, 40, and 60 minutes after intervention. Patients who did not respond to the intervention were excluded from the study within 60 minutes.

Results

The increased mean forced expiratory volume in 1 second and mean peak expiratory flow rate were found to be similar in both groups during the treatment (P=0.304). The mean systolic and diastolic blood pressure recorded at 40 and 60 minutes were significantly lower in the intervention group. During this study, no patient was excluded before 60 minutes.

Conclusion

Administration of dexmedetomidine in addition to standard salbutamol treatment has no beneficial effect in patients with acute asthma attacks and merely causes hypotension in patients.

Cigarette Smoke Exposure, Pediatric Lung Disease, and COVID-19

The detrimental effects of tobacco exposure on children's health are well known. Nonetheless, the prevalence of secondhand or direct cigarette smoke exposure (CSE) in the pediatric population has not significantly decreased over time. On the contrary, the rapid incline in use of e-cigarettes among adolescents has evoked public health concerns since increasing cases of vaping-induced acute lung injury have highlighted the potential harm of these new "smoking" devices. Two pediatric populations are especially vulnerable to the detrimental effects of cigarette smoke. The first group is former premature infants whose risk is elevated both due to their prematurity as well as other risk factors such as oxygen and mechanical ventilation to which they are disproportionately exposed. The second group is children and adolescents with chronic respiratory diseases, in particular asthma and other wheezing disorders. Coronavirus disease 2019 (COVID-19) is a spectrum of diseases caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has spread worldwide over the last year. Here, respiratory symptoms ranging from mild to acute respiratory distress syndrome (ARDS) are at the forefront of COVID-19 cases among adults, and cigarette smoking is associated with worse outcomes in this population, and cigarette smoking is associated with worse outcomes in this population. Interestingly, SARS-CoV-2 infection affects children differently in regard to infection susceptibility, disease manifestations, and complications. Although children carry and transmit the virus, the likelihood of symptomatic infection is low, and the rates of hospitalization and death are even lower when compared to the adult population. However, multisystem inflammatory syndrome is recognized as a serious consequence of SARS-CoV-2 infection in the pediatric population. In addition, recent data demonstrate specific clinical patterns in children infected with SARS-CoV-2 who develop multisystem inflammatory syndrome vs. severe COVID-19. In this review, we highlight the pulmonary effects of CSE in vulnerable pediatric populations in the context of the ongoing SARS-CoV-2 pandemic.

Bacterial lysate therapy for the prevention of wheezing episodes and asthma exacerbations: a systematic review and meta-analysis

Wheezing and asthma are a growing cause of morbidity in children and adults. Treatment is aimed at prevention of disease exacerbations and preservation of lung function. Respiratory viruses are involved in ∼40-60% of exacerbations. Bacterial lysates prevent recurrent respiratory tract infections and might reduce exacerbations. Moreover, immunomodulatory effects have been observed in human and animal studies. Here we aimed to assess the effects of bacterial lysate therapy on preschool wheezing episodes and asthma exacerbation frequency. We performed a systematic literature review based on the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) statement and a meta-analysis using Cochrane Review Manager. Out of 2016 retrieved articles, 22 studies were included, of which five provided sufficient data for a meta-analysis.The use of bacterial lysates showed a decrease of both wheezing episodes (mean difference -2.35 (-3.03- -1.67), p<0.001) and asthma exacerbations in children (mean difference -0.90 (-1.23- -0.57), p<0.001). Additionally, antibiotic use was reduced, and the duration of wheezing episodes was also decreased. No data for adults with asthma are currently available. The immunomodulatory effect seems to be dependent on increased T-helper (Th)1-cell activation and Th2-cell suppression.These favourable effects of bacterial lysates indicate that they show promise as add-on therapy in preschool wheezing and childhood asthma.

Viral infections and wheezing-asthma inception in childhood: is there a role for immunomodulation by oral bacterial lysates?

Severe and recurrent infections of the respiratory tract in early childhood constitute major risk factors for the development of bronchial hyper-responsiveness and obstructive respiratory diseases in later life. In the first years of life, the vast majority of respiratory tract infections (RTI) leading to wheezing and asthma are of a viral origin and severity and recurrence are the consequence of a greater exposure to infectious agents in a period when the immune system is still relatively immature. Therefore, boosting the efficiency of the host immune response against viral infections seems to be a rational preventative approach. In the last decades it has been demonstrated that living in farm environments, i.e. early-life exposure to microbes, may reduce the risk of allergic and infectious disorders, increasing the immune response efficacy. These findings have suggested that treatment with bacterial lysates could promote a nonspecific immunomodulation useful in the prevention of recurrent RTIs and of wheezing inception and persistence. Experimental and clinical studies showing the reduction of RTI frequency and severity in childhood and elucidating the involved mechanisms can support this hypothesis.

Neonatal endotoxin stimulation is associated with a long-term bronchiolar epithelial expression of innate immune and anti-allergic markers that attenuates the allergic response

Allergic asthma is the most common phenotype of the pathology, having an early-onset in childhood and producing a Th2-driven airways remodeling process that leads to symptoms and pathophysiological changes. The avoidance of aeroallergen exposure in early life has been shown to prevent asthma, but without repeated success and with the underlying preventive mechanisms at the beginning of asthma far to be fully recognized. In the present study, we aimed to evaluate if neonatal LPS-induced boost in epithelial host defenses contribute to prevent OVA-induced asthma in adult mice. To this, we focused on the response of bronchiolar club cells (CC), which are highly specialized in maintaining the epithelial homeostasis in the lung. In these cells, neonatal LPS administration increased the expression of TLR4 and TNFα, as well as the immunodulatory/antiallergic proteins: club cell secretory protein (CCSP) and surfactant protein D (SP-D). LPS also prevented mucous metaplasia of club cells and reduced the epidermal growth factor receptor (EGFR)-dependent mucin overproduction, with mice displaying normal breathing patterns after OVA challenge. Furthermore, the overexpression of the epithelial Th2-related molecule TSLP was blunted, and normal TSLP and IL-4 levels were found in the bronchoalveolar lavage. A lower eosinophilia was detected in LPS-pretreated mice, along with an increase in phagocytes and regulatory cells (CD4+CD25+FOXP3+ and CD4+IL-10+), together with higher levels of IL-12 and TNFα. In conclusion, our study demonstrates stable asthma-preventive epithelial effects promoted by neonatal LPS stimulation, leading to the presence of regulatory cells in the lung. These anti-allergic dynamic mechanisms would be overlaid in the epithelium, favored by an adequate epidemiological environment, during the development of asthma.

Early-life origin and prevention of chronic obstructive pulmonary diseases

Chronic obstructive respiratory disorders such as asthma and chronic obstructive pulmonary disease (COPD) have their roots in the womb. Together with a genetic predisposition, prenatal and early-life factors, including maternal smoking, prematurity, and bronchopulmonary dysplasia (BPD), have a pivotal role in later respiratory health. Then, inappropriate responses to respiratory viruses (especially respiratory syncytial virus and rhinovirus) and early allergic sensitization are the strongest contributors to the inception of wheezing and early-onset asthma. There is an urgent need for early disease biomarkers to identify profiles at higher risk of chronic respiratory conditions. Applying the "-omic" technologies to urine, blood and breath condensate, and non-invasive inflammometry seem promising in this regard. The description of specific risk profiles may be the key to the use of targeted personalized therapies.

Pidotimod: a review of its pharmacological features and clinical effectiveness in respiratory tract infections

Introduction: The majority of acute respiratory tract infections (RTIs) are caused by viruses and the overzealous use of antibacterial drugs, when not really required, is a cause for concern. This has led to evaluation of alternative approaches such as boosting the immune response in individuals who are most vulnerable to develop RTIs such as the very young and the elderly. Areas covered: This article overviews the immunostimulant activity and pharmacokinetic properties of pidotimod, and focuses on assessing its role in the treatment and prevention of acute RTIs through evaluation of clinical trials and real-world evidence. Articles were obtained from a full search of Medline, and this was augmented by published clinical studies known to the authors and manufacturer. Expert opinion: Pidotimod's activity was shown to be mediated via multiple pathways of the immune system. Comparison with placebo demonstrated significant advantages for pidotimod in terms of reduced reinfection rates [OR 0.20, 95% CI 0.12 to 0.33; p < 0.00001], a lesser need for antibiotics [mean difference -2.65, 95% CI -3.68 to -1.62; p < 0.00001] and rescue medications, and decreased absenteeism [mean difference-2.99, 95% CI -4.03 to -1.95; p < 0.00001]. No safety concerns were raised in these studies.

Practical and Conceptual Considerations for the Primary Prevention of Asthma

Asthma is among the most common chronic diseases worldwide and is a significant contributor to the global health burden, highlighting the urgent need for primary prevention. This article outlines several practical and conceptual challenges that accompany primary prevention efforts. It advocates for improved predictive modeling to identify those at high-risk of developing asthma using automated algorithms within electronic medical records systems and explanatory modeling to refine understanding of causal pathways. Understanding the many issues that are likely to affect the success of primary prevention efforts helps the community of individuals invested in asthma prevention organize efforts and maximize their impact.

Better understanding of childhood asthma, towards primary prevention - are we there yet? Consideration of pertinent literature

Asthma is a chronic disease, characterized by reversible airway obstruction, airway inflammation and hyper-reactivity. The prevalence of asthma has risen dramatically over the past decade, affecting around 300,000,000 people. The etiology is multifactorial, with genetic, epigenetic, developmental and environmental factors playing a role. A complex interaction between the intrauterine environment, the developing immune system, the infant's microbiome and infectious organisms may lead to the development of allergic sensitization and asthma. Thus, a large number of studies have investigated the risk factors for childhood asthma, with a meticulous search of modifiable factors that could aid in primary prevention.

We present a current literature review from 2014-2017, as well as older classic publications, on the pathogenesis and the potential modifiable factors for primary prevention of asthma. No ideal preventive measure has yet been found. Rather, creating favorable prenatal and postnatal environments, minimal exposure to hostile environmental factors, prevention of infections in early life, allergic desensitization and nutritional modifications could possibly reduce asthma inception. In the era of personalized medicine, identifying individual risk factors and tailoring specific preventive measures is warranted.

Age-Dependent Allergic Asthma Development and Cystathionine Gamma-Lyase Deficiency

AIMS

The pathogenic mechanisms for the higher prevalence of allergic asthma in children than in adults have not been settled. The aim of the present study is to examine whether the age-dependent development of allergic asthma is caused by age-dependent expression of cystathionine gamma-lyase (CSE), a key enzyme that catalyzes the production of hydrogen sulfide (H₂S).

RESULTS

Allergic asthma was induced with ovalbumin in wild-type (WT) and CSE knock-out (KO) mice at young and old ages. CSE expression and H₂S production were lower in immune cells of young WT mice than in those of old WT mice. Coincidentally, more severe asthmatic symptoms with a greater type-2 immunoreaction were found in young WT mice than old WT mice. H₂S supplementation reversed the asthmatic symptoms. Lower expression levels of CSE proteins were also found in human umbilical cord blood mononuclear cells in comparison with that of peripheral blood mononuclear cells from adult people. The age-dependent asthma propensity vanished in CSE-KO mice, but these mice developed more severe asthma than WT mice. More splenocytes were differentiated to type-2 cytokine-generating cells in young WT mice and in CSE-KO mice at all ages. This differentiation was inhibited by H₂S donors. GATA3 translocation to the nucleus and type-2 immunoreaction of splenocytes were inhibited after GATA3 was S-sulfhydrated by H₂S. Innovation and Conclusion: For the first time, this study demonstrated that lower abundance of CSE expression and H₂S production enhances type-2 immunoreaction and renders a higher incidence of allergic asthma at a young age. As such, H₂S level may be a biomarker for asthma development and a H₂S-based strategy can be perceived for asthma prevention and treatment. Antioxid. Redox Signal. 27, 931-944.

Prenatal exposures and the development of childhood wheezing illnesses

PURPOSE OF REVIEW

To critically evaluate and summarize studies published between July 2015 and June 2016 linking prenatal exposures and the onset of childhood wheezing illnesses and to discuss future research directions in this field.

RECENT FINDINGS

The aggregated evidence indicates a consistent detrimental effect of prenatal exposure to parental smoking, outdoor air pollution, and maternal stress on childhood wheezing illnesses. Less consistent evidence suggests an adverse impact of maternal obesity during pregnancy and prenatal exposure to antibiotics on these outcomes. There is insufficient evidence to support an association between in-utero exposure to acetaminophen or prenatal levels of specific nutrients (such as vitamin D, folic acid, or polyunsaturated fatty acids) and childhood wheezing illnesses.

SUMMARY

Several common potentially modifiable prenatal exposures appear to be consistently associated with childhood wheezing illnesses (e.g. parental smoking, outdoor air pollution, and maternal stress). However, the effect of many other prenatal exposures on the onset of childhood wheezing illnesses remains unclear. The existing scientific evidence from the past year does not allow us to make any new recommendations on primary prevention measures. Intervention studies will best demonstrate whether changing the prenatal environment can prevent childhood wheezing illnesses and asthma.

Gut microbiota and allergy/asthma: From pathogenesis to new therapeutic strategies

Asthma and atopy, classically associated with hyper-activation of the T helper 2 (Th2) arm of adaptive immunity, are among the most common chronic illnesses worldwide. Emerging evidence relates atopy and asthma to the composition and function of gut microbiota composition. Moreover, certain gut microbial strains have been shown to inhibit or attenuate immune responses associated with chronic inflammation in experimental models. Although still a relatively nascent field of research, evidence to date suggests that the gut microbiome may represent fertile targets for prevention or management of allergic asthma and other diseases in which adaptive immune dysfunction is a prominent feature. The oral probiotics/prebiotic represents a possible therapeutic for improving asthma and allergic disease. Especially, recent technological developments that permit identification of microbes and their products using culture-independent molecular detection techniques. In this review, we literaturely summarise the aggravation or improvement of metabolic diseases by role of gut microbiota, probiotics/prebiotic treatment.

Mechanisms Mediating Pediatric Severe Asthma and Potential Novel Therapies

Although a rare disease, severe therapy-resistant asthma in children is a cause of significant morbidity and results in utilization of approximately 50% of health-care resources for asthma. Improving control for children with severe asthma is, therefore, an urgent unmet clinical need. As a group, children with severe asthma have severe and multiple allergies, steroid resistant airway eosinophilia, and significant structural changes of the airway wall (airway remodeling). Omalizumab is currently the only add-on therapy that is licensed for use in children with severe asthma. However, limitations of its use include ineligibility for approximately one-third of patients because of serum IgE levels outside the recommended range and lack of clinical efficacy in a further one-third. Pediatric severe asthma is thus markedly heterogeneous, but our current understanding of the different mechanisms underpinning various phenotypes is very limited. We know that there are distinctions between the factors that drive pediatric and adult disease since pediatric disease develops in the context of a maturing immune system and during lung growth and development. This review summarizes the current data that give insight into the pathophysiology of pediatric severe asthma and will highlight potential targets for novel therapies. It is apparent that in order to identify novel treatments for pediatric severe asthma, the challenge of undertaking mechanistic studies using age appropriate experimental models and airway samples from children needs to be accepted to allow a targeted approach of personalized medicine to be achieved.

The microbiome and development of allergic disease

PURPOSE OF REVIEW

First, to review how the global rise in prevalence of asthma prompted studies of the relationships between microbial exposure in early infancy, the rate and pattern of development of immune function, and the development of allergic sensitization and of wheezing in childhood. And, second, to review how those studies laid the groundwork for a possible strategy for primary prevention of asthma through manipulation of the microbiome of the gastrointestinal and/or respiratory tracts.

RECENT FINDINGS

Atopy and asthma are complex diseases thought to result from a 'gene-by-environment' interaction; the rapidity of their rise in prevalence points to a change in environment as most likely causal. Epidemiologic studies noting associations between events in infancy and later development of atopic diseases have suggested that their rise in prevalence is related to a deficiency in microbial exposure in early life. The findings from birth cohort studies of humans and from interventional studies of mice converge in suggesting that a deficiency in microbial colonization of the respiratory or gastrointestinal tract by certain commensal microbes results in skewed development of systemic and/or local immune function that increases susceptibility to allergic sensitization and to viral lower respiratory infection. Recent studies are now honing in on identifying the microbes, or collection of microbes, whose collective functions are necessary for induction of immune tolerance, and thus of reduced susceptibility.

SUMMARY

Atopy and asthma appear to have their roots in an insufficiency of early-life exposure to the diverse environmental microbiota necessary to ensure colonization of the gastrointestinal and/or respiratory tracts with the commensal microbes necessary for induction of balanced, toleragenic immune function. Identification of the commensal bacteria necessary, now ever closer at hand, will lay the groundwork for the development of strategies for primary prevention of atopic disease, especially of childhood asthma.

[Increase in asthma prevalence among young children in France]

INTRODUCTION

Few data on change over time of asthma prevalence in French children are available.

METHODS

Data from the 2012-2013 national health survey of schoolchildren conducted in a random sample of almost 20,000 children in the last year of nursery school were compared to those which had been collected in 2005-2006 in the same grade level using the same methodology.

RESULTS

In the 2012-2013 survey, children had a lifetime prevalence of asthma of 11.0% with 11.8% reporting wheezing in the preceding year. Asthma was more frequent and more often uncontrolled in children from families with low socioeconomic status. Compared to the survey conducted in the same grade level in 2005-2006, the prevalence ratios adjusted for children's gender and obesity, family structure, parental unemployment and region were 1.13 [1.05-1.21] for lifetime asthma and 1.12 [1.05-1.17] for past-year wheezing.

CONCLUSION

In France, the prevalence of asthma in young children increased between 2005 and 2012. The socioeconomic status of children's parents affects both asthma prevalence and control.

Metabolomic profile of children with recurrent respiratory infections

Recurrent respiratory infections (RRI) represent a widespread condition which has a severe social and economic impact. Immunostimulants are used for their prevention. It is crucial to better characterize children with RRI to refine their diagnosis and identify effective personalized prevention strategies. Metabolomics is a high-dimensional biological method that can be used for hypothesis-free biomarker profiling, examining a large number of metabolites in a given sample using spectroscopic techniques. Multivariate statistical data analysis then enables us to infer which metabolic information is relevant to the biological characterization of a given physiological or pathological condition. This can lead to the emergence of new, sometimes unexpected metabolites, and hitherto unknown metabolic pathways, enabling the formulation of new pathogenetic hypotheses, and the identification of new therapeutic targets. The aim of our pilot study was to apply mass-spectrometry-based metabolomics to the analysis of urine samples from children with RRI, comparing these children's biochemical metabolic profiles with those of healthy peers. We also compared the RRI children's and healthy controls' metabolomic urinary profiles after the former had received pidotimod treatment for 3 months to see whether this immunostimulant was associated with biochemical changes in the RRI children's metabolic profile. 13 children (age range 3-6 yeas) with RRI and 15 matched per age healthy peers with no history of respiratory diseases or allergies were enrolled. Their metabolomic urine samples were compared before and after the RRI children had been treated with pidotimod for a period of 3 months. Metabolomic analyses on the urine samples were done using mass spectrometry combined with ultra-performance liquid chromatography (UPLC-MS). The resulting spectroscopic data then underwent multivariate statistical analysis and the most relevant variables characterizing the two groups were identified. Data modeling with post-transformation of PLS2-Discriminant Analysis (ptPLS2-DA) generated a robust model capable of discriminating the urine samples from children with RRI from those of healthy controls (R²=0.92,Q²_CV7-fold=0.75, p-value<0.001). The dataset included 1502 time per mass variables, and 138 of them characterized the difference between the two groups. Thirty-five of these distinctive 138 variables persisted in the profiles of the children with RRI after pidotimod treatment. Metabolomics can discriminate children with RRI from healthy controls, suggesting that the former have a dysregulated metabolic profile. Among the variables characterizing children with RRI there are metabolites that may reflect the presence of a different microbiome. After pidotimod treatment, the metabolic profile of the children with RRI was no longer very different from that of the healthy controls, except for the persistence of some microbiome-related variables. We surmise that pidotimod partially "restores" the altered metabolic profile of children with RRI, without modifying the metabolites related to the composition of the gut microbiota. In the light of these results, we hypothesize a potential synergic effect of the combined use of immunostimulants and probiotics for the purpose of prevention in children with RRI.

D-tryptophan from probiotic bacteria influences the gut microbiome and allergic airway disease

BACKGROUND

Chronic immune diseases, such as asthma, are highly prevalent. Currently available pharmaceuticals improve symptoms but cannot cure the disease. This prompted demands for alternatives to pharmaceuticals, such as probiotics, for the prevention of allergic disease. However, clinical trials have produced inconsistent results. This is at least partly explained by the highly complex crosstalk among probiotic bacteria, the host's microbiota, and immune cells. The identification of a bioactive substance from probiotic bacteria could circumvent this difficulty.

OBJECTIVE

We sought to identify and characterize a bioactive probiotic metabolite for potential prevention of allergic airway disease.

METHODS

Probiotic supernatants were screened for their ability to concordantly decrease the constitutive CCL17 secretion of a human Hodgkin lymphoma cell line and prevent upregulation of costimulatory molecules of LPS-stimulated human dendritic cells.

RESULTS

Supernatants from 13 of 37 tested probiotic strains showed immunoactivity. Bioassay-guided chromatographic fractionation of 2 supernatants according to polarity, followed by total ion chromatography and mass spectrometry, yielded C₁₁H₁₂N₂O₂ as the molecular formula of a bioactive substance. Proton nuclear magnetic resonance and enantiomeric separation identified D-tryptophan. In contrast, L-tryptophan and 11 other D-amino acids were inactive. Feeding D-tryptophan to mice before experimental asthma induction increased numbers of lung and gut regulatory T cells, decreased lung T_H2 responses, and ameliorated allergic airway inflammation and hyperresponsiveness. Allergic airway inflammation reduced gut microbial diversity, which was increased by D-tryptophan.

CONCLUSIONS

D-tryptophan is a newly identified product from probiotic bacteria. Our findings support the concept that defined bacterial products can be exploited in novel preventative strategies for chronic immune diseases.

Functional Effects of Cigarette Smoke-Induced Changes in Airway Smooth Muscle Mitochondrial Morphology

Long-term exposure to cigarette smoke (CS) triggers airway hyperreactivity and remodeling, effects that involve airway smooth muscle (ASM). We previously showed that CS destabilizes the networked morphology of mitochondria in human ASM by regulating the expression of mitochondrial fission and fusion proteins via multiple signaling mechanisms. Emerging data link regulation of mitochondrial morphology to cellular structure and function. We hypothesized that CS-induced changes in ASM mitochondrial morphology detrimentally affect mitochondrial function, leading to CS effects on contractility and remodeling. Here, ASM cells were exposed to 1% cigarette smoke extract (CSE) for 48 h to alter mitochondrial fission/fusion, or by inhibiting the fission protein Drp1 or the fusion protein Mfn2. Mitochondrial function was assessed via changes in bioenergetics or altered rates of proliferation and apoptosis. Our results indicate that both exposure to CS and inhibition of mitochondrial fission/fusion proteins affect mitochondrial function (i.e., energy metabolism, proliferation, and apoptosis) in ASM cells. In vivo, the airways in mice chronically exposed to CS are thickened and fibrotic, and the expression of proteins involved in mitochondrial function is dramatically altered in the ASM of these mice. We conclude that CS-induced changes in mitochondrial morphology (fission/fusion balance) correlate with mitochondrial function, and thus may control ASM proliferation, which plays a central role in airway health. J. Cell. Physiol. 232: 1053-1068, 2017. © 2016 Wiley Periodicals, Inc.

Future Research Directions in Asthma. An NHLBI Working Group Report

Asthma is a common chronic disease without cure. Our understanding of asthma onset, pathobiology, classification, and management has evolved substantially over the past decade; however, significant asthma-related morbidity and excess healthcare use and costs persist. To address this important clinical condition, the NHLBI convened a group of extramural investigators for an Asthma Research Strategic Planning workshop on September 18-19, 2014, to accelerate discoveries and their translation to patients. The workshop focused on (1) in utero and early-life origins of asthma, (2) the use of phenotypes and endotypes to classify disease, (3) defining disease modification, (4) disease management, and (5) implementation research. This report summarizes the workshop and produces recommendations to guide future research in asthma.

Probiotics for treatment and primary prevention of allergic diseases and asthma: looking back and moving forward

Microbial ecosystems cover the surface of the human body and it is becoming increasingly clear that our modern environment has profound effects on microbial composition and diversity. A dysbiotic gut microbiota has been associated with allergic diseases and asthma in cross-sectional and observational studies. In an attempt to restore this dysbiosis, probiotics have been evaluated in randomized controlled trials. Here, we review treatment and primary prevention studies, recent meta-analyses, and discuss the current understanding of the role of probiotics in this context. Many meta-analyses have shown a moderate benefit of probiotics for eczema prevention, whereas there is less evidence of a benefit for other allergic manifestations. Because of very low quality evidence and heterogeneity between studies, specific advice on the most effective regimens cannot yet be given - not even for eczema prevention. To be able to adopt results into specific recommendations, international expert organizations stress the need for well-designed studies.

Examining causes of the urban (inner city) asthma epidemic: Implementing new management strategies

Asthma in the inner city contributes to high morbidity and mortality, and, in school children, reduced school attendance and alteration in academic performance. There is a need to improve asthma care in the inner city by reducing asthma exacerbations. Methods are currently available to predict and prevent seasonal exacerbations of asthma. In addition, new medications are being developed that will be effective in improving pulmonary function and reducing asthma exacerbations. School-centered asthma programs can also be helpful to assist children and clinicians in applying asthma treatment plans and assuring optimal adherence to these plans.

Changing Trends in Asthma Prevalence Among Children

BACKGROUND

Childhood asthma prevalence doubled from 1980 to 1995 and then increased more slowly from 2001 to 2010. During this second period, racial disparities increased. More recent trends remain to be described.

METHODS

We analyzed current asthma prevalence using 2001-2013 National Health Interview Survey data for children ages 0 to 17 years. Logistic regression with quadratic terms was used to test for nonlinear patterns in trends. Differences between demographic subgroups were further assessed with multivariate models controlling for gender, age, poverty status, race/ethnicity, urbanicity, and geographic region.

RESULTS

Overall, childhood asthma prevalence increased from 2001 to 2009 followed by a plateau then a decline in 2013. From 2001 to 2013, multivariate logistic regression showed no change in prevalence among non-Hispanic white and Puerto Rican children and those in the Northeast and West; increasing prevalence among 10- to 17-year-olds, poor children, and those living in the South; increasing then plateauing prevalence among 5- to 9-year-olds, near-poor children, and non-Hispanic black children; and increasing then decreasing prevalence among 0- to 4-year-olds, nonpoor, and Mexican children and those in the Midwest. Non-Hispanic black-white disparities stopped increasing, and Puerto Rican children remained with the highest prevalence.

CONCLUSIONS

Current asthma prevalence ceased to increase among children in recent years and the non-Hispanic black-white disparity stopped increasing due mainly to plateauing prevalence among non-Hispanic black children.

Promising candidates for allergy prevention

Recent advances in understanding environmental risk factors for allergic diseases in children have led to renewed efforts aimed at prevention. Factors that modify the probability of developing allergies include prenatal exposures, mode of delivery, diet, patterns of medication use, and exposure to pets and farm animals. Recent advances in microbial detection techniques demonstrate that exposure to diverse microbial communities in early life is associated with a reduction in allergic disease. In fact, microbes and their metabolic products might be essential for normal immune development. Identification of these risk factors has provided new targets for prevention of allergic diseases, and possibilities of altering microbial exposure and colonization to reduce the incidence of allergies is a promising approach. This review examines the rationale, feasibility, and potential effect for the prevention of childhood allergic diseases and explores possible strategies for enhancing exposure to beneficial microbes.

Risk factors for asthma: is prevention possible?

Asthma is one of the most common diseases in the world, resulting in a substantial burden of disease. Although rates of deaths due to asthma worldwide have reduced greatly over the past 25 years, no available therapeutic regimens can cure asthma, and the burden of asthma will continue to be driven by increasing prevalence. The reasons for the increase in asthma prevalence have not been defined, which limits the opportunities to develop targeted primary prevention measures. Although associations are reported between a wide range of risk factors and childhood asthma, substantiation of causality is inherently difficult from observational studies, and few risk factors have been assessed in primary prevention studies. Furthermore, none of the primary prevention intervention strategies that have undergone scrutiny in randomised controlled trials has provided sufficient evidence to lead to widespread implementation in clinical practice. A better understanding of the factors that cause asthma is urgently needed, and this knowledge could be used to develop public health and pharmacological primary prevention measures that are effective in reducing the prevalence of asthma worldwide. To achieve this it will be necessary to think outside the box, not only in terms of risk factors for the causation of asthma, but also the types of novel primary prevention strategies that are developed, and the research methods used to provide the evidence base for their implementation. In the interim, public health efforts should remain focused on measures with the potential to improve lung and general health, such as: reducing tobacco smoking and environmental tobacco smoke exposure; reducing indoor and outdoor air pollution and occupational exposures; reducing childhood obesity and encouraging a diet high in vegetables and fruit; improving feto-maternal health; encouraging breastfeeding; promoting childhood vaccinations; and reducing social inequalities.

Omalizumab therapy for children and adolescents with severe allergic asthma

Omalizumab, a therapeutic humanized monoclonal antibody specific for human IgE, was introduced in clinical practice more than a decade ago as an add-on therapy for moderate-to-severe allergic asthma in patients aged ≥12 years. Omalizumab has been demonstrated to be effective in adults with uncontrolled persistent asthma, with an excellent safety profile. In simple terms, omalizumab works by inhibiting the allergic cascade, that is, by neutralization of the circulating free IgE. This leads to reduction in the quantity of cell-bound IgE, downregulation of high-affinity IgE receptors, and, eventually, prevention of mediator release from effector cells. Evidence is far less abundant on the role of omalizumab in pediatric asthma. Although efficacy and safety of omalizumab in children and adolescents with uncontrolled, persistent allergic asthma has been recognized as well, further studies are needed to clarify a number of open questions in this specific patient population.

Affect of Early Life Oxygen Exposure on Proper Lung Development and Response to Respiratory Viral Infections

Children born preterm often exhibit reduced lung function and increased severity of response to respiratory viruses, suggesting that premature birth has compromised proper development of the respiratory epithelium and innate immune defenses. Increasing evidence suggests that premature birth promotes aberrant lung development likely due to the neonatal oxygen transition occurring before pulmonary development has matured. Given that preterm infants are born at a point of time where their immune system is also still developing, early life oxygen exposure may also be disrupting proper development of innate immunity. Here, we review current literature in hopes of stimulating research that enhances understanding of how the oxygen environment at birth influences lung development and host defense. This knowledge may help identify those children at risk for disease and ideally culminate in the development of novel therapies that improve their health.

Pidotimod: the state of art

Despite the use of antibiotics and vaccines, the frequency of respiratory tract infections is still high and these infections interest a wide range of patients, from children to aged people, including in particular these extreme categories because of the deficiency of their immune system, due to immaturity in the former case and to "immunosenescence" in the latter. For that reason immunostimulant drugs are getting more important to prevent and to attenuate infections. Pidotimod (3-L-pyroglutamyl-L-thiazolidine-4carboxylic acid) is a synthetic dipeptide with immunomodulatory properties. We reviewed studies conducted on different categories of patients, with particular attention on children and senile patients suffering from recurrent respiratory tract infections, associated, or not, with asthma or COPD. The outcomes considered are both clinical and laboratory parameters. The common end-point of these studies is that Pidotimod has an immunomodulatory activity which is able both to improve the clinical conditions of patients and to enhance and stimulate their immunity cells (lymphocytes but not only) functions acting on adaptive and innate immunity. Pidotimod is also able to increase the concentration of salivary IgA directed against bacteria; furthermore, it can modulate airway epithelial cells functions up-regulating the expression of toll-like receptors and acting on adhesion molecules. According to studies conducted on patients with atopic asthma, it seems that Pidotimod could affect T-lymphocytes balance with a possible addictional anti-allergic activity. Furthermore, it has been demonstrated an improvement of FEV1 and PEF in asthmatic patients treated with Pidotimod. Main clinical outcomes are the reduction of the number of infectious episodes, lesser severity of signs and symptoms and, consequently, a reduction in use of antibiotics and symptomatic drugs, less working and school days lost, less mortality and morbidity. The studies considered give positive results, confirming Pidotimod's efficacy. Furthermore, many studies show a good safety profile of the drug, without recording serious adverse events and mutagenic potential, and a very low incidence of side effects. Pidotimod is also a more safe solution in patients subjected to vaccination, if compared to lyophilized polibacterial, which can't be administered for thirty days before vaccination.

Microbiota in allergy and asthma and the emerging relationship with the gut microbiome

Asthma and atopy, classically associated with hyper-activation of the T helper 2 (Th2) arm of adaptive immunity, are among the most common chronic illnesses worldwide. Emerging evidence relates atopy and asthma to the composition and function of the human microbiome, the collection of microbes that reside in and on and interact with the human body. The ability to interrogate microbial ecology of the human host is due in large part to recent technological developments that permit identification of microbes and their products using culture-independent molecular detection techniques. In this review we explore the roles of respiratory, gut, and environmental microbiomes in asthma and allergic disease development, manifestation, and attenuation. Though still a relatively nascent field of research, evidence to date suggests that the airway and/or gut microbiome may represent fertile targets for prevention or management of allergic asthma and other diseases in which adaptive immune dysfunction is a prominent feature.

Asthma

Asthma is the most common inflammatory disease of the lungs. The prevalence of asthma is increasing in many parts of the world that have adopted aspects of the Western lifestyle, and the disease poses a substantial global health and economic burden. Asthma involves both the large-conducting and the small-conducting airways, and is characterized by a combination of inflammation and structural remodelling that might begin in utero. Disease progression occurs in the context of a developmental background in which the postnatal acquisition of asthma is strongly linked with allergic sensitization. Most asthma cases follow a variable course, involving viral-induced wheezing and allergen sensitization, that is associated with various underlying mechanisms (or endotypes) that can differ between individuals. Each set of endotypes, in turn, produces specific asthma characteristics that evolve across the lifecourse of the patient. Strong genetic and environmental drivers of asthma interconnect through novel epigenetic mechanisms that operate prenatally and throughout childhood. Asthma can spontaneously remit or begin de novo in adulthood, and the factors that lead to the emergence and regression of asthma, irrespective of age, are poorly understood. Nonetheless, there is mounting evidence that supports a primary role for structural changes in the airways with asthma acquisition, on which altered innate immune mechanisms and microbiota interactions are superimposed. On the basis of the identification of new causative pathways, the subphenotyping of asthma across the lifecourse of patients is paving the way for more-personalized and precise pathway-specific approaches for the prevention and treatment of asthma, creating the real possibility of total prevention and cure for this chronic inflammatory disease.

Emerging issues in pediatric asthma: gaps in EPR-3 guidelines for infants and children

There are many complexities to the treatment of infants and children with recurrent wheezing and asthma. The National Heart, Lung and Blood Institute's (NHLBI's) Expert Panel Report-3 (EPR-3), published in 2007, provides guidance to clinicians who care for infants and children with asthma. Since that time, many important clinical trials have further informed the evidence base available to clinicians. In this manuscript, new approaches to long-term therapy, intermittent fixed-dose and dynamic dose therapies, and emerging therapies for asthma are reviewed. Further, additional gaps in guideline-based care and areas for future research are discussed.

Early-life origins of chronic respiratory diseases: understanding and promoting healthy ageing

Chronic obstructive respiratory disorders such as asthma and chronic obstructive pulmonary disease often originate early in life. In addition to a genetic predisposition, prenatal and early-life environmental exposures have a persistent impact on respiratory health. Acting during a critical phase of lung development, these factors may change lung structure and metabolism, and may induce maladaptive responses to harmful agents, which will affect the whole lifespan. Some environmental factors, such as exposure to cigarette smoke, type of childbirth and diet, may be modifiable, but it is more difficult to influence other factors, such as preterm birth and early exposure to viruses or allergens. Here, we bring together recent literature to analyse the critical aspects involved in the early stages of lung development, going back to prenatal and perinatal events, and we discuss the mechanisms by which noxious factors encountered early on may have a lifelong impact on respiratory health. We briefly comment on the need for early disease biomarkers and on the possible role of "-omic" technologies in identifying risk profiles predictive of chronic respiratory conditions. Such profiles could guide the ideation of effective preventive strategies and/or targeted early lifestyle or therapeutic interventions.